release: 0.80.0 (improvement/e9.5-onboarding-access)

Release notes for the epic: bilingual mail, one-mail-one-click approval, order-independent gates
with named states, canonical Gmail identity, the admin lifeline for sign-ups stuck outside, and the
four-round closing review that converged 12 -> 4 -> 3 -> 2.

Dockerfile

@@ -45,18 +45,34 @@ RUN adduser --disabled-password --gecos "" appuser \
     && mkdir -p /downloads \
     && chown appuser /app /downloads
 
-# ffmpeg: merge separate video+audio streams + postprocessing. Deno: the JavaScript runtime
-# yt-dlp uses to solve YouTube's "n" signature challenge for the web player clients (required
-# alongside the PO token, else only storyboards are offered). yt-dlp auto-detects deno on PATH.
+# ffmpeg: merge separate video+audio streams + postprocessing, and the Plex VAAPI transcode (E6 S1).
+# intel-media-va-driver (iHD): the VA driver ffmpeg's h264_vaapi needs — libva2 ships in the base but
+# no driver, so without this `vainfo`/`h264_vaapi` fail and transcode silently falls back to libx264.
+# Harmless on hosts with no /dev/dri (the driver just goes unused). Deno: the JavaScript runtime yt-dlp
+# uses to solve YouTube's "n" signature challenge for the web player clients (required alongside the PO
+# token, else only storyboards are offered). yt-dlp auto-detects deno on PATH.
 ARG DENO_VERSION=v2.9.1
 RUN apt-get update \
-    && apt-get install -y --no-install-recommends ffmpeg unzip curl ca-certificates \
+    && apt-get install -y --no-install-recommends ffmpeg intel-media-va-driver unzip curl ca-certificates \
     && curl -fsSL "https://github.com/denoland/deno/releases/download/${DENO_VERSION}/deno-x86_64-unknown-linux-gnu.zip" -o /tmp/deno.zip \
     && unzip -o /tmp/deno.zip -d /usr/local/bin \
     && chmod +x /usr/local/bin/deno \
     && rm /tmp/deno.zip \
     && rm -rf /var/lib/apt/lists/*
 
+# Intel NEO OpenCL runtime (intel-opencl-icd) — needed by the Plex transcode's HDR/10-bit HW path, which
+# tone-maps HDR→SDR on the GPU via `tonemap_opencl` (Gen 9.5 / UHD 630 can't tonemap in the VAAPI VPP, so
+# OpenCL is the only HW route; without this the 10-bit branch drops to CPU libx264). NEO was REMOVED from
+# Debian trixie (this base = python:3.12-slim = trixie), so it's pulled from **bookworm** — the 22.43 there
+# still supports Gen 9.5 and its .deb runs on trixie (verified live on the prod UHD 630). The bookworm apt
+# source is added only for this one install and removed after, so it can't drift the rest of the image.
+# Harmless on hosts with no /dev/dri or no OpenCL use (the runtime just sits unused).
+RUN printf 'Types: deb\nURIs: http://deb.debian.org/debian\nSuites: bookworm\nComponents: main\nSigned-By: /usr/share/keyrings/debian-archive-keyring.pgp\n' > /etc/apt/sources.list.d/bookworm.sources \
+    && apt-get update \
+    && apt-get install -y --no-install-recommends -t bookworm intel-opencl-icd \
+    && rm /etc/apt/sources.list.d/bookworm.sources \
+    && rm -rf /var/lib/apt/lists/*
+
 # Install from the PINNED lock (requirements.lock, generated from requirements.txt) so the image is
 # byte-reproducible and the exact versions are the ones pip-audit scanned in CI — not whatever floats
 # up from the floor ranges on build day. Regenerate the lock when requirements.txt changes (see its header).

VERSION

@@ -1 +1 @@
-0.72.1
+0.80.0

backend/alembic/versions/0074_download_credentials.py

@@ -0,0 +1,46 @@
+"""download_credentials (S6: per-user, per-host yt-dlp cookie/auth store)
+
+Each user stores their OWN login cookies (Netscape cookies.txt) for an auth-walled download host
+(Facebook, Instagram, …), Fernet-encrypted at rest. A download of a yt-dlp-supported, auth-walled
+link on that host is retried with the acting user's cookie. Unique per (user_id, host_key) so a
+user holds at most one credential per host. Empty for every existing install; forward-only in
+practice (a downgrade just drops the table + its secrets).
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0074_download_credentials"
+down_revision: Union[str, None] = "0073_saved_view_source"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "download_credentials",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column(
+            "user_id",
+            sa.Integer(),
+            sa.ForeignKey("users.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column("host_key", sa.String(length=64), nullable=False),
+        sa.Column("cookies_enc", sa.Text(), nullable=False),
+        sa.Column(
+            "created_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False
+        ),
+        sa.Column(
+            "updated_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False
+        ),
+        sa.UniqueConstraint("user_id", "host_key", name="uq_download_credential"),
+    )
+    op.create_index("ix_download_credentials_user_id", "download_credentials", ["user_id"])
+
+
+def downgrade() -> None:
+    op.drop_index("ix_download_credentials_user_id", table_name="download_credentials")
+    op.drop_table("download_credentials")

backend/alembic/versions/0075_playlist_sync_baseline.py

@@ -0,0 +1,26 @@
+"""playlist synced_video_ids (S7: 3-way merge baseline for two-way YouTube sync)
+
+The one-directional "local wins" push is replaced by a 3-way merge that classifies each item
+against the last-synced state. That needs the raw ordered id set as a baseline, not just the
+`synced_fingerprint` hash. Add a nullable `synced_video_ids` (JSON list) column; NULL on every
+existing row means "no baseline yet" — the first merge then unions losslessly and records one.
+Forward-only in practice (a downgrade just drops the column).
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0075_playlist_sync_baseline"
+down_revision: Union[str, None] = "0074_download_credentials"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column("playlists", sa.Column("synced_video_ids", sa.Text(), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column("playlists", "synced_video_ids")

backend/alembic/versions/0076_media_asset_kind.py

@@ -0,0 +1,41 @@
+"""media_assets.media_kind (E7 S5a: the video|audio|file discriminator for the media library)
+
+Adds a stored media-kind to each asset so the library can gate its actions on it (play/edit for
+media, download-only for a generic uploaded file) instead of re-deriving from codecs in prose. The
+column is the single home of the invariant `downloads.mediakind.derive` computes at finalize.
+
+Backfill for existing rows: a stored video codec -> 'video', an audio-only codec -> 'audio', an
+editor derivative (source_kind='edit', which carries no codecs but is always a video clip) ->
+'video'. Rows still pending/errored (no codecs, not an edit) stay NULL — kind is set when they
+finalize. Empty `media_kind` never reaches the UI: only `ready`/`done` rows render actions, and
+those are all backfilled here.
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0076_media_asset_kind"
+down_revision: Union[str, None] = "0075_playlist_sync_baseline"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column("media_assets", sa.Column("media_kind", sa.String(length=16), nullable=True))
+    op.execute(
+        """
+        UPDATE media_assets
+           SET media_kind = CASE
+               WHEN vcodec IS NOT NULL THEN 'video'
+               WHEN acodec IS NOT NULL THEN 'audio'
+               WHEN source_kind = 'edit' THEN 'video'
+               ELSE NULL
+           END
+        """
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("media_assets", "media_kind")

backend/alembic/versions/0077_plex_playback_class.py

@@ -0,0 +1,54 @@
+"""plex_items playback-class facet (E7: filter the feed by Direct Play / Direct Stream / Transcode)
+
+Adds the columns the playback-class filter needs:
+  * transcode_hw   — for a `playable="transcode"` item, whether the prod iGPU can hardware-transcode it
+                     (codec HW-decodable AND 8-bit SDR) vs software-only. NULL for non-transcode items.
+  * video_bit_depth — the source video bit depth (from the Plex media Stream), NULL until probed.
+  * media_probed_at — watermark for the bit-depth backfill (NULL = not yet probed).
+
+Backfill for existing rows: `transcode_hw` is derived from the ALREADY-stored `codec_video` alone (the
+same HW-decodable allow-list `plex.sync.HW_DECODABLE_CODECS` / `plex.stream` use), so the filter works
+immediately after migration. Bit depth is unknown for existing rows (the cheap Plex listing doesn't
+carry it), so a 10-bit/HDR HEVC is provisionally 'hw' here and later refined to 'sw' by the bit-depth
+backfill (`plex.sync._probe_media_batch`) once its Stream is probed. `video_bit_depth`/`media_probed_at`
+start NULL.
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0077_plex_playback_class"
+down_revision: Union[str, None] = "0076_media_asset_kind"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column("plex_items", sa.Column("transcode_hw", sa.Boolean(), nullable=True))
+    op.add_column("plex_items", sa.Column("video_bit_depth", sa.Integer(), nullable=True))
+    op.add_column(
+        "plex_items", sa.Column("media_probed_at", sa.DateTime(timezone=True), nullable=True)
+    )
+    op.create_index("ix_plex_items_transcode_hw", "plex_items", ["transcode_hw"])
+    # Codec-only derivation for existing rows — keep this codec set identical to
+    # plex.sync.HW_DECODABLE_CODECS. Bit depth is unknown here, so provisionally 8-bit (→ hw for a
+    # decodable codec); the bit-depth backfill downgrades 10-bit/HDR HEVC to sw later.
+    op.execute(
+        """
+        UPDATE plex_items
+           SET transcode_hw = CASE
+               WHEN playable = 'transcode'
+               THEN lower(codec_video) IN ('h264','hevc','h265','vp9','vc1','mpeg2video')
+               ELSE NULL
+           END
+        """
+    )
+
+
+def downgrade() -> None:
+    op.drop_index("ix_plex_items_transcode_hw", table_name="plex_items")
+    op.drop_column("plex_items", "media_probed_at")
+    op.drop_column("plex_items", "video_bit_depth")
+    op.drop_column("plex_items", "transcode_hw")

backend/alembic/versions/0078_password_revoked_at.py

@@ -0,0 +1,58 @@
+"""users.password_revoked_at — remember that SEC-10 dropped a preset password
+
+Revision ID: 0078_password_revoked_at
+Revises: 0077_plex_playback_class
+Create Date: 2026-09-02
+
+SEC-10 (`auth.revoke_preset_password_if_unverified`) nulls `password_hash` when an account whose email
+was never verified is attested (Google adoption, or admin approval). That left NO trace, and
+password-reset eligibility keyed off `password_hash IS NOT NULL` — so such an account could neither
+sign in (no password) nor request a reset link (not "eligible"): a permanent lockout with a silent,
+uniform response at every step.
+
+This column is that trace. A row with `password_revoked_at` set is a local account that HAD a password
+and had it revoked, so the reset flow treats it as eligible again. Setting a password (reset-confirm or
+/auth/set-password) clears the stamp. A Google-only account that never had a password keeps it NULL and
+stays reset-ineligible by design — its owner adds a password from Settings while signed in.
+
+Backfill: the signature is exact and narrow — a local (google_sub IS NULL), non-demo account with NO
+password could ONLY have got there through the revoke. Registration always sets a hash, the setup
+wizard sets one too, every Google row carries a google_sub (the adoption path assigns it BEFORE
+revoking), and nothing in the codebase ever clears google_sub. Stamp those with the current time so
+they become recoverable without operator intervention.
+
+Deliberately NOT also requiring `email_verified = false`, even though the revoke only fires on an
+unverified account: verifying is exactly what such a victim does NEXT. The revoke does not invalidate
+the outstanding verification token, so clicking the emailed link sets email_verified=True while
+password_hash stays NULL — and that row has no route back at all (reset ineligible, resend refuses an
+already-verified address, and set-password needs a signed-in session the account can no longer obtain:
+no password to sign in with, and no Google identity). Those are the victims who most need the stamp,
+so the predicate must not exclude them.
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0078_password_revoked_at"
+down_revision: Union[str, None] = "0077_plex_playback_class"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "users",
+        sa.Column("password_revoked_at", sa.DateTime(timezone=True), nullable=True),
+    )
+    op.execute(
+        "UPDATE users SET password_revoked_at = now() "
+        "WHERE password_hash IS NULL "
+        "AND google_sub IS NULL "
+        "AND is_demo = false"
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("users", "password_revoked_at")

backend/alembic/versions/0079_email_canonical.py

@@ -0,0 +1,65 @@
+"""email_canonical on users + invites, for matching one mailbox across Gmail spellings
+
+Revision ID: 0079_email_canonical
+Revises: 0078_password_revoked_at
+Create Date: 2026-09-04
+
+Gmail delivers `x.y@gmail.com`, `xy@gmail.com` and `xy+tag@gmail.com` to ONE mailbox; the invite gate
+only lowercased. On 2026-09-03 that turned an approved user's Google sign-in into a silent second
+access request (OAuth returns the account's stored primary, which need not be the spelling they typed)
+and left prod with two user rows for one mailbox.
+
+The backfill below reproduces `app.utils.canonical_email` in SQL. That duplication is deliberate — a
+migration must not import application code that will keep changing — but it means the two have to
+agree; `test_canonical_email_backfill_matches_the_helper` pins them together.
+
+Deliberately NOT unique. Prod already carries canonical duplicates: two approved invites for one
+mailbox dating back to 2026-06-16, and two active user rows from the 2026-09-03 walkthrough. Merging
+accounts is a judgement call about people's data, not something a migration gets to do on its own, so
+this migration only records the canonical form and leaves the duplicates in place for a human.
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0079_email_canonical"
+down_revision: str | None = "0078_password_revoked_at"
+branch_labels: str | None = None
+depends_on: str | None = None
+
+# Mirrors app.utils.canonical_email: Gmail (and its googlemail alias) loses dots and any `+tag` from
+# the local part and lands on gmail.com; every other domain is only lowercased, because the dot rule
+# is not guaranteed elsewhere — and does not hold for Workspace custom domains unless their admin
+# enabled it.
+_CANON_SQL = """
+    CASE
+      WHEN split_part(lower({col}), '@', 2) IN ('gmail.com', 'googlemail.com')
+       -- an empty local part after stripping falls through to plain lowercase, as the helper does
+       AND replace(split_part(split_part(lower({col}), '@', 1), '+', 1), '.', '') <> ''
+      THEN replace(split_part(split_part(lower({col}), '@', 1), '+', 1), '.', '') || '@gmail.com'
+      ELSE lower({col})
+    END
+"""
+
+
+def _backfill(table: str) -> None:
+    op.execute(
+        f"UPDATE {table} SET email_canonical = {_CANON_SQL.format(col='email')} "
+        f"WHERE email IS NOT NULL"
+    )
+
+
+def upgrade() -> None:
+    for table in ("users", "invites"):
+        op.add_column(
+            table,
+            sa.Column("email_canonical", sa.String(length=320), nullable=False, server_default=""),
+        )
+        _backfill(table)
+        op.create_index(f"ix_{table}_email_canonical", table, ["email_canonical"])
+
+
+def downgrade() -> None:
+    for table in ("users", "invites"):
+        op.drop_index(f"ix_{table}_email_canonical", table_name=table)
+        op.drop_column(table, "email_canonical")

backend/alembic/versions/0080_google_email.py

@@ -0,0 +1,32 @@
+"""users.google_email — the address Google asserts, kept beside the one the user registered with
+
+Revision ID: 0080_google_email
+Revises: 0079_email_canonical
+Create Date: 2026-09-04
+
+Since 0079's follow-up a Google sign-in no longer overwrites `users.email`, so a deliberate
+`me+siftlode@gmail.com` survives being linked to a Google account whose primary is `me@gmail.com`.
+That leaves two true addresses for one account and only one of them stored. This column holds the
+other, so the account menu and the Settings sign-in row can show which address Google actually
+answers with.
+
+No backfill is possible: Google's answer is only known at sign-in. Accounts linked before this
+column existed carry NULL until their owner next signs in with Google — and for the majority the two
+addresses are identical anyway, where the UI shows nothing either way.
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0080_google_email"
+down_revision: str | None = "0079_email_canonical"
+branch_labels: str | None = None
+depends_on: str | None = None
+
+
+def upgrade() -> None:
+    op.add_column("users", sa.Column("google_email", sa.String(length=320), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column("users", "google_email")

backend/alembic/versions/0081_invite_invited_at.py

@@ -0,0 +1,34 @@
+"""invites.invited_at — when the admin actually told this person the door was open
+
+Revision ID: 0081_invite_invited_at
+Revises: 0080_google_email
+Create Date: 2026-09-05
+
+Whitelisting an address stays SILENT by design: the operator is opening a door as a possibility,
+usually after agreeing it with the person, and a row can sit approved for weeks without anyone
+registering. Telling them is therefore a separate, deliberate act — a send button on the row.
+
+Which raises the one question the admin cannot otherwise answer: "did I already write to them?"
+Without a record the only failure mode is writing to a real person twice, which is exactly the
+nudging the silent-by-default design exists to avoid. The audit log holds the event, but not where
+the decision is made.
+
+NULL means "never invited from here", which is true of every existing row: no backfill is possible
+or wanted, since the historic approval mails answered a REQUEST rather than inviting anyone.
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0081_invite_invited_at"
+down_revision: str | None = "0080_google_email"
+branch_labels: str | None = None
+depends_on: str | None = None
+
+
+def upgrade() -> None:
+    op.add_column("invites", sa.Column("invited_at", sa.DateTime(timezone=True), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column("invites", "invited_at")

backend/alembic/versions/0082_invite_lang.py

@@ -0,0 +1,34 @@
+"""invites.lang — the language this person asked us in
+
+Revision ID: 0082_invite_lang
+Revises: 0081_invite_invited_at
+Create Date: 2026-09-05
+
+The mails an access request produces — approved, denied, invited — go to an address that often has
+no account yet, so there is no `preferences.language` to read. The signal does exist, though, and
+only at the moment of the request: the language of the page the form was submitted from, or the
+locale Google reported for a sign-in we refused. Recording it there is what lets the decision mail
+answer in the requester's own language instead of an admin's guess about a stranger.
+
+Captured rather than derived, for the third time in this epic: `preferences.language` (S6) and
+`google_email` (S3) both taught that a signal which exists only in one moment cannot be backfilled
+later. So no backfill here either — NULL means "we were never told", which is the honest state for
+every historic row, and for every address an admin whitelists by hand. Those fall back to English
+unless the admin picks otherwise on the invitation send.
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0082_invite_lang"
+down_revision: str | None = "0081_invite_invited_at"
+branch_labels: str | None = None
+depends_on: str | None = None
+
+
+def upgrade() -> None:
+    op.add_column("invites", sa.Column("lang", sa.String(length=8), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column("invites", "lang")

backend/app/audit.py

@@ -27,9 +27,17 @@ class AuditAction:
     USER_SUSPEND = "user_suspend"
     USER_UNSUSPEND = "user_unsuspend"
     USER_DELETE = "user_delete"
+    # E9.5 S5: an admin let a stuck registrant in, or re-sent their confirmation link. Both are
+    # recorded because both are the admin acting ON someone's access, not merely reading a list.
+    USER_ACTIVATE = "user_activate"
+    USER_VERIFY_RESEND = "user_verify_resend"
     INVITE_APPROVE = "invite_approve"
     INVITE_DENY = "invite_deny"
     INVITE_ADD = "invite_add"
+    INVITE_DELETE = "invite_delete"
+    # E9.5 S6: the admin chose to tell someone their address is whitelisted. Adding the address is
+    # silent, so this is the act that actually reaches a person — and the one worth a record.
+    INVITE_SEND = "invite_send"
     DEMO_ADD = "demo_add"
     DEMO_REMOVE = "demo_remove"
     DEMO_RESET = "demo_reset"
@@ -44,6 +52,9 @@ class AuditAction:
     SYNC_RESUME = "sync_resume"
     # Scheduler job outcome / run-summary (actor_id set = a manual "run now"; NULL = automatic)
     JOB_RUN = "job_run"
+    # Per-user download cookie/auth credential set or removed (the value is NEVER recorded)
+    DOWNLOAD_CREDENTIAL_SET = "download_credential_set"
+    DOWNLOAD_CREDENTIAL_DELETE = "download_credential_delete"
     # The log itself was cleared (a single row survives the clear as tamper-evidence)
     AUDIT_CLEAR = "audit_clear"
 

backend/app/auth.py

@@ -7,11 +7,13 @@ from sqlalchemy.orm import Session
 from starlette.requests import HTTPConnection
 
 from app import email as email_mod
+from app import mailtext
 from app import sysconfig
 from app.config import settings
 from app.db import get_db
 from app.models import Invite, User
 from app.security import decrypt_optional
+from app.utils import canonical_email
 
 PASSWORD_MIN_LEN = 10
 
@@ -63,16 +65,126 @@ def has_write_scope(user: User) -> bool:
     return WRITE_SCOPE in tok.scopes.split()
 
 
+def env_allowed_canonicals() -> set[str]:
+    """The env bootstrap allow-list, in CANONICAL form — the only shape it may be compared in.
+
+    S3 canonicalised the Invite branch of `is_allowed` and left this one matching the literal string,
+    which is the 2026-09-03 lockout with a different source of truth: an operator who writes
+    `first.last@gmail.com` into ALLOWED_EMAILS is refused when Google answers with the undotted
+    primary, and a `+tag`ged entry can never match at all, because a Google account cannot contain a
+    `+`. The addresses themselves stay literal wherever we MAIL them (`admin_notify_groups`); only
+    the comparison is canonical.
+    """
+    return env_admin_canonicals() | {canonical_email(e) for e in settings.allowed_email_set}
+
+
+def env_admin_canonicals() -> set[str]:
+    """The env ADMIN_EMAILS bootstrap list, canonical — for the role check only. Kept separate from
+    `env_allowed_canonicals` because being listed as an admin also grants access, but being allowed
+    does not make anyone an admin."""
+    return {canonical_email(e) for e in settings.admin_email_set}
+
+
 def is_allowed(db: Session, email: str) -> bool:
     """May this email sign in? An approved Invite is the source of truth; the env
-    ALLOWED_EMAILS/ADMIN_EMAILS remain a bootstrap fallback (e.g. a fresh DB)."""
+    ALLOWED_EMAILS/ADMIN_EMAILS remain a bootstrap fallback (e.g. a fresh DB).
+
+    Matched on the CANONICAL form (utils.canonical_email), not the literal string. Gmail delivers
+    every dotted / `+tagged` spelling to one mailbox, so approving one spelling always meant approving
+    that mailbox — matching literally only produced the 2026-09-03 lockout, where an approved user's
+    Google sign-in became a silent second access request because OAuth returned the undotted primary.
+
+    One canonical form can match SEVERAL invite rows (prod carries approved pairs for one mailbox,
+    the oldest from 2026-06-16). An approved row among them grants access: the API cannot flip an
+    approved invite to denied (`_decide` only accepts a pending one), so approved-beside-denied means
+    the admin approved that mailbox under a different spelling, not that they revoked it. Revoking is
+    deleting the invite row or suspending the account — both still work, since a deleted row is no
+    longer here to match and suspension is enforced at sign-in.
+    """
     if not email:
         return False
-    email = email.lower()
-    inv = db.execute(select(Invite).where(Invite.email == email)).scalar_one_or_none()
-    if inv is not None:
-        return inv.status == "approved"
-    return email in settings.allowed_email_set or email in settings.admin_email_set
+    canon = canonical_email(email)
+    statuses = (
+        db.execute(select(Invite.status).where(Invite.email_canonical == canon)).scalars().all()
+    )
+    if statuses:
+        return "approved" in statuses
+    return canon in env_allowed_canonicals()
+
+
+def can_activate(db: Session, user: User) -> bool:
+    """Is this account merely waiting for an admin to finish letting it in?
+
+    True when it is inactive but its address is ALREADY allowed — the shape roadmap UX-25 describes:
+    the admin approved the address, the person signed up afterwards, and nothing connects the two
+    (the Access-requests queue only offers Approve on a still-pending invite).
+
+    Gated on `is_allowed`, the same function the sign-in paths consult, because activating an address
+    that is NOT allowed manufactures an inconsistent account: password sign-in only checks
+    `is_active` and would let them in, while their Google sign-in would be turned away and silently
+    reopened as a fresh access request. Letting in someone with no approved invite is the whitelist
+    box's job — that action says so out loud.
+
+    Lives in core so the admin surface and the /api/me badge count answer from ONE definition; a
+    button that appears and a number that counts must never disagree about who is stuck.
+    """
+    if user.is_demo or user.is_suspended or user.is_active:
+        return False
+    return is_allowed(db, user.email)
+
+
+def count_pending_activations(db: Session) -> int:
+    """How many sign-ups are waiting on an admin click (see can_activate). Drives the admin badge.
+
+    Deliberately NOT "everyone who cannot sign in": an account that has simply not confirmed its
+    address yet is waiting on its owner, not on the admin, and badging that would nag about something
+    the admin did not cause. It is still listed on the admin screen — with a re-send — because the
+    mail may never have arrived.
+    """
+    # Narrowed in SQL, then decided by can_activate itself — so the number the badge shows and the
+    # button the admin sees cannot drift apart by one of them re-deriving the rule.
+    rows = (
+        db.execute(
+            select(User).where(
+                User.is_demo.is_(False),
+                User.is_suspended.is_(False),
+                User.is_active.is_(False),
+            )
+        )
+        .scalars()
+        .all()
+    )
+    return sum(1 for u in rows if can_activate(db, u))
+
+
+def find_user_by_email(db: Session, email: str) -> User | None:
+    """The account someone means when they type an address at sign-in, password-reset or
+    verify-resend. None when there isn't exactly one answer.
+
+    Exact spelling wins. Failing that, the address is resolved to its mailbox
+    (utils.canonical_email) — so a password chosen at registration still works when the person types
+    another spelling of their own Gmail, and so the three flows that look an account up by typed
+    address stop being dead ends. Before this, requesting a reset for `xy@gmail.com` on an account
+    registered as `x.y@gmail.com` issued nothing and said nothing: the endpoint answers uniformly by
+    design, so the user got silence and no way in.
+
+    SEVERAL canonical candidates return None rather than a guess. That case is real — prod carries two
+    accounts for one mailbox — and picking one of them for a password sign-in would hand someone the
+    wrong account. The callers all treat None as "no such account", which is the uniform,
+    non-enumerating answer they already gave.
+    """
+    if not email:
+        return None
+    email = email.strip().lower()
+    exact = db.execute(select(User).where(User.email == email)).scalar_one_or_none()
+    if exact is not None:
+        return exact
+    candidates = (
+        db.execute(select(User).where(User.email_canonical == canonical_email(email)))
+        .scalars()
+        .all()
+    )
+    return candidates[0] if len(candidates) == 1 else None
 
 
 def get_or_create_demo_user(db: Session) -> User:
@@ -119,6 +231,9 @@ def purge_user(db: Session, user: User, background: BackgroundTasks) -> None:
     touch any browser session — each caller handles its own."""
     email = user.email.lower()
     user_id = user.id
+    # Read the language off the row while it still exists — the confirmation below is queued as a
+    # background task that runs after this session (and this user) are gone.
+    lang = mailtext.lang_for_user(user)
     tok = user.token
     # Both are stored encrypted — decrypt for the revoke call (the access-token fallback was passing
     # ciphertext, so a token row with no refresh token silently failed to revoke). decrypt_optional so a
@@ -130,13 +245,25 @@ def purge_user(db: Session, user: User, background: BackgroundTasks) -> None:
     )
     # Raw delete so Postgres applies ON DELETE CASCADE / SET NULL on every dependent table.
     db.execute(delete(User).where(User.id == user_id))
-    db.execute(delete(Invite).where(Invite.email == email))
+    # Every canonically-equal invite goes, not just the literal spelling: is_allowed matches on the
+    # canonical form, so leaving a sibling row behind would keep granting access to a mailbox whose
+    # account was just erased — and prod really does carry approved pairs for one mailbox.
+    #
+    # Unless ANOTHER account still lives on that mailbox — prod carries that too (two user rows for
+    # one Gmail mailbox). Then NO invite goes, not even the literal one: is_allowed matches
+    # canonically, so every row here is what keeps the survivor allowed, and removing any of them
+    # would refuse their next Google sign-in and reopen it as a fresh access request — this epic's
+    # founding bug, caused by its own cleanup. `delete_invite` refuses for exactly this reason; the
+    # user row is already gone by now, so this query sees only the others.
+    canon = canonical_email(email)
+    if db.execute(select(User.id).where(User.email_canonical == canon)).first() is None:
+        db.execute(delete(Invite).where(Invite.email_canonical == canon))
     db.commit()
     if google_token:
         background.add_task(revoke_google_token, google_token)
     # Confirm the erasure to the (now former) user — GDPR good practice, and covers both the
     # self-service and admin deletion paths since both funnel through here.
-    background.add_task(email_mod.send_account_deleted, email, operator_contact())
+    background.add_task(email_mod.send_account_deleted, email, lang, operator_contact())
 
 
 ACTIVE_ACCOUNT_HEADER = "x-siftlode-account"

backend/app/config.py

@@ -186,6 +186,21 @@ class Settings(BaseSettings):
     download_supervisor_poll_seconds: int = 3
     # Grace between SIGTERM and SIGKILL when stopping a child (matches run_ffmpeg's escalation).
     download_kill_grace_seconds: int = 5
+    # --- worker-child resource de-prioritization ---
+    # The download/edit child (yt-dlp + ffmpeg) shares ONE LAN box with the API, Postgres, and Plex
+    # playback. Without a priority handicap a CPU re-encode pegs every core for ~30s and starves web
+    # requests + playback until it finishes. The child lowers its OWN priority at startup — inherited
+    # by every ffmpeg/yt-dlp descendant — so any foreground work always wins. Each knob is best-effort
+    # and independently disable-able with 0.
+    download_child_nice: int = 10  # CPU nice increment applied to the child; 0 = don't renice
+    download_child_ionice_class: int = 3  # best-effort IO class (3 = idle); 0 = leave IO untouched
+    # Cap the browser-safe re-encode's encoder threads so a transcode can't claim every core. 0 =
+    # reserve one core for foreground work (max(1, cpu_count - 1)); >0 pins exactly that many.
+    download_ffmpeg_threads: int = 0
+    # Throttle the retention GC's whole-tree orphan file sweep so its rglob can't monopolize disk IO
+    # in the API process: sleep `pause_ms` after every `batch` files touched. pause_ms=0 disables.
+    download_gc_sweep_pause_ms: int = 20
+    download_gc_sweep_batch: int = 400
     # Total cache size cap across ALL users (bytes). When >0 and exceeded, the GC evicts the
     # least-recently-accessed ready assets until under it. 0 = unlimited (disk is the limit).
     download_total_max_bytes: int = 0
@@ -193,6 +208,10 @@ class Settings(BaseSettings):
     download_default_max_bytes: int = 5_368_709_120  # 5 GiB
     download_default_max_concurrent: int = 2
     download_default_max_jobs: int = 50
+    # Per-file cap for local uploads (E7). Unlike a download (whose size is unknown until the worker
+    # finishes), an upload's size is known at ingest, so this bounds a single file directly; the
+    # user's overall byte footprint is still governed by download_default_max_bytes.
+    download_upload_max_bytes: int = 524_288_000  # 500 MiB
     # Retention: an asset expires this many days after its last access; the GC job then
     # deletes it (once no job references it) after an additional grace window.
     download_retention_days: int = 30
@@ -232,14 +251,29 @@ class Settings(BaseSettings):
     plex_sync_interval_min: int = 360
     # How often the incremental Plex→Siftlode watch-state reconcile runs, in minutes (Phase C):
     # a cheap history + on-deck pull plus a re-push of any states that failed their immediate push.
-    plex_watch_sync_interval_min: int = 30
+    # 15 min (S2): with Plex now the source of truth (prompt write-back on the ~10s checkpoint +
+    # Plex-authoritative pull), a faster incremental pull keeps Siftlode close to Plex-side changes.
+    plex_watch_sync_interval_min: int = 15
     # How often the FULL watch-state reconcile runs, in minutes (Phase C). A whole-section rescan
     # that catches what the incremental history feed can't — notably an un-watch done on the Plex
     # side — so it runs far less often (daily) than the incremental pass.
     plex_watch_reconcile_interval_min: int = 1440
-    # Max concurrent transcodes for the P3 fallback. Low by default — CPU-only transcode is
-    # expensive; direct-serve (browser-compatible files) has no such limit.
+    # Max concurrent transcode sessions (playable="transcode"). Low by default — the software-fallback
+    # re-encode is CPU-heavy (the VAAPI hardware path is far cheaper and could sustain more); direct-serve
+    # and remux (stream-copy) are not capped by this.
     plex_max_transcodes: int = 4
+    # --- Transcode (playable="transcode") re-encode tuning (E6 S1) ---
+    # Hardware-encoder policy: "auto" = VAAPI (h264_vaapi) when the iGPU render node is present AND the
+    # source codec is hardware-decodable, else libx264 software; "on" = force VAAPI wherever the render
+    # node exists (skip the decodability gate); "off" = always software. See plex/stream.py `_select_encode`.
+    plex_transcode_hw: str = "auto"
+    # Software-fallback libx264 tuning (IGNORED on the VAAPI path). `preset` trades CPU for size; `crf`
+    # trades quality for size (lower = better + bigger). `max_height` caps the SOFTWARE transcode's output
+    # height (0 = keep source) so a CPU re-encode of a tall source stays affordable — the GPU path always
+    # encodes at source resolution.
+    plex_transcode_preset: str = "veryfast"
+    plex_transcode_crf: int = 20
+    plex_transcode_max_height: int = 1080
     # Where on-the-fly HLS remux segments are written (transient, reaped). Empty → a `.plex-hls`
     # dir under download_root. On localdev the download_root is a slow Windows bind-mount, so point
     # this at a fast container-local path (e.g. /var/tmp/plex-hls); prod's download_root is fast

backend/app/downloads/credentials.py

@@ -0,0 +1,258 @@
+"""Per-user, per-host download cookies — the single source of truth for "does the acting user's
+cookie apply to this download, and how does that keep the result private".
+
+Two call sites depend on ONE consistent answer (house rule: an invariant lives in shared code, not
+in prose):
+  * `enqueue` salts the MediaAsset cache signature with the user id WHEN a cookie applies, so the
+    authed download becomes a PRIVATE asset that is never cache-served to another user.
+  * the worker attaches the cookie file to yt-dlp ONLY when a cookie still applies AND the asset it
+    is downloading into is that private, salted identity — so a cookie can never poison a shared
+    asset (the load-bearing cross-user privacy fix).
+
+Both go through `cookie_salt` / `authed_format_sig` / `host_key_for_url` here, so they can't drift.
+
+Security controls enforced here:
+  * **host scope (SEC-12)** — `host_key_for_url` matches the download URL's netloc against a curated
+    registry via the netloc-scoped `_host_is`, so a cookie is only ever offered to the exact site it
+    belongs to; an arbitrary `?url=` (or a look-alike host) resolves to no host_key and gets no
+    cookie.
+  * **secret handling** — cookies are Fernet-encrypted at rest; the blob is only ever decrypted
+    in-worker into a 0600 file that is unlinked in a `finally`, and is never returned by a route,
+    logged, or written to a job's error/snapshot.
+"""
+
+import logging
+import os
+from pathlib import Path
+
+from sqlalchemy import select
+from sqlalchemy.orm import Session
+
+from app.downloads import formats
+from app.downloads.adapters import _host_is
+from app.models import DownloadCredential
+from app.security import decrypt_optional, encrypt
+
+log = logging.getLogger("siftlode.downloads.credentials")
+
+
+class HostSpec:
+    """A supported cookie host: a short canonical `key` (stored on the credential + folded into the
+    cache salt), a human `label` for the UI, and the netloc `domains` it matches."""
+
+    __slots__ = ("key", "label", "domains")
+
+    def __init__(self, key: str, label: str, domains: tuple[str, ...]):
+        self.key = key
+        self.label = label
+        self.domains = domains
+
+
+# Curated registry (user's call: seed the common auth-walled hosts now). One `key` can cover several
+# domains of the same site. Add a host by adding a row — the FE dropdown, host-scope guard, and salt
+# all derive from this, so there is nothing else to wire up.
+SUPPORTED_HOSTS: tuple[HostSpec, ...] = (
+    HostSpec("facebook", "Facebook", ("facebook.com", "fb.watch")),
+    HostSpec("instagram", "Instagram", ("instagram.com",)),
+    HostSpec("twitter", "X (Twitter)", ("twitter.com", "x.com")),
+    HostSpec("tiktok", "TikTok", ("tiktok.com",)),
+    HostSpec("reddit", "Reddit", ("reddit.com",)),
+)
+
+_BY_KEY: dict[str, HostSpec] = {h.key: h for h in SUPPORTED_HOSTS}
+
+
+def is_supported_host(host_key: str) -> bool:
+    return host_key in _BY_KEY
+
+
+def host_label(host_key: str) -> str:
+    spec = _BY_KEY.get(host_key)
+    return spec.label if spec else host_key
+
+
+def host_key_for_url(url: str | None) -> str | None:
+    """The supported host_key whose domains own `url`'s netloc, or None. Netloc-scoped (via
+    `_host_is`), so a look-alike host ('myfacebook.com', 'facebook.com.evil') never matches. When
+    several specs could match, the most-specific (longest matched domain) wins so the result is
+    deterministic across the enqueue and worker call sites."""
+    if not url:
+        return None
+    from urllib.parse import urlparse
+
+    host = urlparse(url).netloc.lower()
+    if not host:
+        return None
+    best_key: str | None = None
+    best_len = -1
+    for spec in SUPPORTED_HOSTS:
+        for dom in spec.domains:
+            if _host_is(host, dom) and len(dom) > best_len:
+                best_key, best_len = spec.key, len(dom)
+    return best_key
+
+
+def cookie_salt(user_id: int, host_key: str) -> str:
+    """The cache-signature salt for a cookie-authed download. Keyed by user id + host so the authed
+    asset is private to that user (never dedup-shared) and stable across that user's own re-adds."""
+    return f"cookie:{user_id}:{host_key}"
+
+
+def authed_format_sig(spec: dict, user_id: int, host_key: str) -> str:
+    """The salted `format_sig` an authed download for (user, host) resolves to — the private asset
+    identity. Both enqueue (to create it) and the worker (to recognise it) compute it HERE."""
+    return formats.format_sig(spec, salt=cookie_salt(user_id, host_key))
+
+
+def salt_for_enqueue(db: Session, user_id: int, url: str | None) -> str | None:
+    """At enqueue: the cache salt to apply if this user has a cookie for `url`'s host, else None (a
+    normal shared download). Returns the salt string so the caller passes it straight to
+    `format_sig(spec, salt=...)`."""
+    host_key = host_key_for_url(url)
+    if host_key is None:
+        return None
+    if get_credential(db, user_id, host_key) is None:
+        return None
+    return cookie_salt(user_id, host_key)
+
+
+# --- storage (CRUD) ---------------------------------------------------------------------------
+
+
+def get_credential(db: Session, user_id: int, host_key: str) -> DownloadCredential | None:
+    return db.execute(
+        select(DownloadCredential).where(
+            DownloadCredential.user_id == user_id, DownloadCredential.host_key == host_key
+        )
+    ).scalar_one_or_none()
+
+
+class InvalidCookies(ValueError):
+    """The pasted cookies aren't a usable Netscape cookies.txt — surfaced as a 400 by the route."""
+
+
+def validate_cookies(raw: str) -> str:
+    """Sanity-check a pasted cookies.txt (Netscape format) and return the cleaned text. yt-dlp reads
+    the Netscape format: comment/`#` lines plus TAB-separated cookie lines (domain, flag, path,
+    secure, expiry, name, value). We don't fully parse — just reject obvious non-cookie paste (empty,
+    or no tab-separated data line) so a mistaken paste fails HERE with a clear message rather than
+    silently producing a cookie file yt-dlp ignores."""
+    text = (raw or "").strip()
+    if not text:
+        raise InvalidCookies("empty")
+    has_data_line = any(
+        line.strip() and not line.lstrip().startswith("#") and "\t" in line
+        for line in text.splitlines()
+    )
+    if not has_data_line:
+        raise InvalidCookies("format")
+    # Netscape cookie files must end with a newline for some parsers; normalise.
+    return text if text.endswith("\n") else text + "\n"
+
+
+def upsert_credential(db: Session, user_id: int, host_key: str, raw: str) -> DownloadCredential:
+    """Create or replace this user's cookie blob for `host_key`. Caller has validated host_key is
+    supported and `raw` via `validate_cookies`. Does NOT commit (the route commits with the audit
+    row so the trail can't drift). The blob is encrypted here; the plaintext never leaves this call."""
+    cred = get_credential(db, user_id, host_key)
+    enc = encrypt(raw)
+    if cred is None:
+        cred = DownloadCredential(user_id=user_id, host_key=host_key, cookies_enc=enc)
+        db.add(cred)
+    else:
+        cred.cookies_enc = enc
+    return cred
+
+
+def delete_credential(db: Session, user_id: int, host_key: str) -> bool:
+    """Delete this user's cookie for `host_key`. Returns whether a row existed. Does NOT commit."""
+    cred = get_credential(db, user_id, host_key)
+    if cred is None:
+        return False
+    db.delete(cred)
+    return True
+
+
+def status_list(db: Session, user_id: int) -> list[dict]:
+    """The supported hosts with this user's configured/updated state — the write-only Settings view.
+    Never includes the blob."""
+    have = {
+        c.host_key: c
+        for c in db.execute(
+            select(DownloadCredential).where(DownloadCredential.user_id == user_id)
+        ).scalars()
+    }
+    out = []
+    for spec in SUPPORTED_HOSTS:
+        cred = have.get(spec.key)
+        out.append(
+            {
+                "host_key": spec.key,
+                "label": spec.label,
+                "configured": cred is not None,
+                "updated_at": cred.updated_at.isoformat() if cred is not None else None,
+            }
+        )
+    return out
+
+
+# --- worker: resolve + write the cookie file --------------------------------------------------
+
+
+def resolve_cookiefile(
+    db: Session,
+    user_id: int,
+    url: str | None,
+    asset_format_sig: str,
+    spec: dict,
+    staging: Path,
+) -> Path | None:
+    """In the worker child: the cookies.txt to hand yt-dlp for this download, or None.
+
+    The double gate that prevents cross-user leakage:
+      1. a credential must still exist for `url`'s host (host-scoped via `host_key_for_url`), AND
+      2. the asset being downloaded into must BE this user's private, salted identity
+         (`asset_format_sig == authed_format_sig(...)`).
+
+    If (2) fails the asset is the SHARED (unsalted) one — attaching the cookie would poison the
+    global cache with a private-group video, so we attach nothing. An unreadable blob (rotated key →
+    InvalidToken) also yields None; the download then fails honestly on the login wall (S3's
+    `login_required`)."""
+    host_key = host_key_for_url(url)
+    if host_key is None:
+        return None
+    cred = get_credential(db, user_id, host_key)
+    if cred is None:
+        return None
+    if asset_format_sig != authed_format_sig(spec, user_id, host_key):
+        return None  # shared asset — never attach a cookie to a non-private identity
+    raw = decrypt_optional(cred.cookies_enc)
+    if not raw:
+        log.warning(
+            "download cookie for user %s host %s could not be decrypted (rotated key?) — "
+            "proceeding without it",
+            user_id,
+            host_key,
+        )
+        return None
+    return _write_cookiefile(raw, staging)
+
+
+def _write_cookiefile(raw: str, staging: Path) -> Path:
+    """Write the cookie blob to a private 0600 file under `staging/.auth/` and return its path.
+
+    Deliberately NOT in the staging root: the download retry loop unlinks every file it finds there,
+    and `_produced_file` picks the largest file there as the output — either would corrupt a
+    cookies.txt in the root. A `.auth` SUBDIR survives both (they skip directories) and is still
+    removed by the parent worker's staging cleanup on a hard kill. The caller unlinks it in a
+    `finally` on the normal/exception paths."""
+    auth_dir = staging / ".auth"
+    auth_dir.mkdir(mode=0o700, exist_ok=True)
+    path = auth_dir / "cookies.txt"
+    # Open with 0600 from the start (don't create world-readable then chmod).
+    fd = os.open(path, os.O_WRONLY | os.O_CREAT | os.O_TRUNC, 0o600)
+    try:
+        os.write(fd, raw.encode("utf-8"))
+    finally:
+        os.close(fd)
+    return path

backend/app/downloads/edit.py

@@ -25,6 +25,7 @@ import hashlib
 import json
 import logging
 import math
+import os
 import queue
 import shutil
 import subprocess
@@ -32,9 +33,21 @@ import threading
 import time
 from pathlib import Path
 
+from app.config import settings
+
 log = logging.getLogger("siftlode.edit")
 
 
+def encode_thread_cap() -> int:
+    """How many encoder threads a browser-safe re-encode may use. `download_ffmpeg_threads` when the
+    admin pinned one (>0), else reserve a core for foreground work (max(1, cpu_count - 1)). Shared by
+    the ffmpeg `-threads` flag and the child's `OMP_NUM_THREADS` so both honour the same budget."""
+    n = settings.download_ffmpeg_threads
+    if n > 0:
+        return n
+    return max(1, (os.cpu_count() or 2) - 1)
+
+
 class EditAborted(Exception):
     """Raised by run_ffmpeg when the job was paused/canceled mid-encode."""
 
@@ -425,18 +438,42 @@ _BROWSER_SAFE_VCODEC = ("h264",)
 _BROWSER_SAFE_ACODEC = ("aac", "mp3")
 
 
-def parse_probe_streams(payload: str) -> tuple[str | None, str | None]:
-    """(video_codec, audio_codec) out of ffprobe's JSON stream list, lowercased.
-
-    JSON, not the flat `default=nw=1` output: there the fields arrive in ffprobe's own struct
-    order, which puts `codec_name` BEFORE `codec_type`, so a line-by-line "remember the last
-    codec_type" parser attributes every name to the PREVIOUS stream. Measured on real downloads:
-    an ordinary H.264+AAC mp4 probed as `v=aac a=None` — the browser-playability check then
-    believed the video stream was AAC and re-encoded a perfectly fine file on every download."""
+def run_ffprobe_json(
+    path: Path,
+    *,
+    show_streams: bool = False,
+    show_format: bool = False,
+    entries: str | None = None,
+) -> dict | None:
+    """One ffprobe call → its parsed JSON dict, or None on any failure (timeout, non-zero exit,
+    missing binary, unparseable output). The SINGLE ffprobe-JSON-invocation point in the downloads
+    package: the browser-playability codec probe here and the shared media probe (`probe.probe_media`,
+    used by both the download worker's finalize and the upload ingest) both go through it, so the
+    subprocess flags/timeout/error handling live in one place instead of drifting copies."""
+    args = ["ffprobe", "-v", "error"]
+    if show_streams:
+        args.append("-show_streams")
+    if show_format:
+        args.append("-show_format")
+    if entries:
+        args += ["-show_entries", entries]
+    args += ["-of", "json", str(path)]
     try:
-        streams = json.loads(payload or "{}").get("streams") or []
-    except ValueError:
-        return None, None
+        out = subprocess.run(args, capture_output=True, text=True, timeout=30, check=True).stdout
+        return json.loads(out)
+    except (subprocess.TimeoutExpired, subprocess.CalledProcessError, OSError, ValueError):
+        return None
+
+
+def _codecs_from_streams(streams: list) -> tuple[str | None, str | None]:
+    """(video_codec, audio_codec) lowercased from an ffprobe JSON stream list — the first of each kind.
+
+    Parsed from the JSON `streams` list, NOT ffprobe's flat `default=nw=1` output: there the fields
+    arrive in ffprobe's own struct order, which puts `codec_name` BEFORE `codec_type`, so a line-by-line
+    "remember the last codec_type" parser attributes every name to the PREVIOUS stream. Measured on real
+    downloads: an ordinary H.264+AAC mp4 probed as `v=aac a=None` — the browser-playability check then
+    believed the video stream was AAC and re-encoded a perfectly fine file on every download. Reading each
+    stream dict by its own `codec_type` is immune to that ordering."""
     vcodec = acodec = None
     for s in streams:
         name = (s.get("codec_name") or "").lower() or None
@@ -451,26 +488,10 @@ def parse_probe_streams(payload: str) -> tuple[str | None, str | None]:
 def probe_codecs(path: Path) -> tuple[str | None, str | None]:
     """Return (video_codec, audio_codec) lowercased via one ffprobe call; None for a missing
     stream or if ffprobe fails (a failed probe is treated as 'leave it alone' upstream)."""
-    try:
-        out = subprocess.run(
-            [
-                "ffprobe",
-                "-v",
-                "error",
-                "-show_entries",
-                "stream=codec_type,codec_name",
-                "-of",
-                "json",
-                str(path),
-            ],
-            capture_output=True,
-            text=True,
-            timeout=30,
-            check=True,
-        ).stdout
-    except (subprocess.TimeoutExpired, subprocess.CalledProcessError, OSError):
+    data = run_ffprobe_json(path, entries="stream=codec_type,codec_name")
+    if data is None:
         return None, None
-    return parse_probe_streams(out)
+    return _codecs_from_streams(data.get("streams") or [])
 
 
 def probe_duration(path: Path) -> int:
@@ -510,11 +531,12 @@ def browser_transcode_flags(
 
 
 def build_browser_safe_cmd(
-    src: Path, dest: Path, reencode_video: bool, reencode_audio: bool
+    src: Path, dest: Path, reencode_video: bool, reencode_audio: bool, threads: int | None = None
 ) -> list[str]:
     """ffmpeg command that lands `src` as a browser-safe mp4 (faststart): re-encode only the
     stream(s) that need it (libx264 / aac), stream-copy the rest, always into mp4. `-progress
-    pipe:1` streams machine-readable progress for run_ffmpeg."""
+    pipe:1` streams machine-readable progress for run_ffmpeg. `threads` caps the encoder so a
+    re-encode can't claim every core on the shared box (see the worker-child de-prioritization)."""
     cmd = [
         "ffmpeg",
         "-y",
@@ -534,6 +556,8 @@ def build_browser_safe_cmd(
         else ["-c:v", "copy"]
     )
     cmd += ["-c:a", "aac", "-b:a", "192k"] if reencode_audio else ["-c:a", "copy"]
+    if threads and threads > 0:
+        cmd += ["-threads", str(threads)]
     cmd += ["-movflags", "+faststart", str(dest)]
     return cmd
 

backend/app/downloads/errors.py

@@ -24,6 +24,16 @@ _RULES: tuple[tuple[str, str], ...] = (
     # Some extractors (e.g. Reddit) gate content behind a logged-in account: "Account
     # authentication is required." — an auth wall we deliberately don't cross, not a transient error.
     ("authentication is required", "login_required"),
+    # Closed-group / private-post auth walls (Facebook groups, Instagram private, …). yt-dlp phrases
+    # these many ways; the common thread is "you must be signed in" or its own suggestion to supply
+    # cookies. Treating the cookie suggestion as an auth signal is what makes a login-walled link read
+    # honestly (and stay non-retryable) when the acting user has no usable cookie for that host.
+    ("log in to", "login_required"),
+    ("login required", "login_required"),
+    ("you must be logged in", "login_required"),
+    ("only available for registered users", "login_required"),
+    ("use --cookies", "login_required"),
+    ("--cookies-from-browser", "login_required"),
     # Geo-restricted.
     ("in your country", "geo_blocked"),
     ("available in your location", "geo_blocked"),
@@ -42,6 +52,10 @@ _RULES: tuple[tuple[str, str], ...] = (
     ("account associated with this video has been terminated", "unavailable"),
     ("this video is not available", "unavailable"),
     ("this video has been removed", "unavailable"),
+    # yt-dlp doesn't support this site at all ("Unsupported URL: …") — distinct from an auth wall on a
+    # supported site. Non-retryable: no cookie or retry can make an unsupported host downloadable.
+    ("unsupported url", "unsupported_host"),
+    ("no video could be found in this url", "unsupported_host"),
     # DRM.
     ("drm protected", "drm"),
     ("drm-protected", "drm"),

backend/app/downloads/formats.py

@@ -5,13 +5,16 @@ of truth for what file gets produced. `format_sig` hashes exactly the fields tha
 OUTPUT BYTES, so two users picking equivalent settings share one cached MediaAsset.
 `build_ydl_opts` turns a spec into a yt-dlp options dict (format selector + postprocessors).
 
-spec shape (all keys optional; defaults applied by `normalize`):
+spec shape (all keys optional; defaults + browser-playability clamp applied by `normalize`):
     mode           "av" (audio+video) | "v" (video-only) | "a" (audio-only)
     max_height     int | null (null = best)
-    container      "mp4" | "mkv" | "webm" | null (merge/remux target for av/v)
-    audio_format   "m4a" | "mp3" | "opus" | null (extract target for mode "a")
-    vcodec         "h264" | "vp9" | "av1" | null (preference, best-effort)
+    container      always coerced to "mp4" (the only universally browser-playable container)
+    audio_format   "m4a" | "mp3" (mode "a" extract target; anything else — e.g. opus — → "m4a")
+    vcodec         always coerced to null → H.264 selected (see `normalize`); no opt-out
     embed_subs     bool     embed_chapters bool     embed_thumbnail bool     sponsorblock bool
+
+`normalize` clamps container/vcodec/audio_format so EVERY download plays in-browser (E7); the
+`container`/`vcodec` keys survive only so an old stored profile deserializes without error.
 """
 
 import hashlib
@@ -50,10 +53,12 @@ _DEFAULTS = {
 # prefer H.264+AAC (browser/iOS-compatible) rather than yt-dlp's default VP9/Opus best.
 # v3: mp4 compat now *selects* H.264 (avc1) with a progressive fallback + re-encodes the rare
 # AV1/VP9-only result to H.264, so cached AV1 assets must re-derive (fixes iOS broken-player).
-_SIG_VERSION = 3
+# v4: EVERY download is clamped to the mp4/H.264/AAC compat profile (no more mkv/webm/VP9/AV1/Opus
+# opt-out), so any asset cached under an old non-compat spec — or a stale non-H.264 mp4 that slipped
+# the v3 net — must re-derive through the current browser-safe guarantee.
+_SIG_VERSION = 4
 
 _SPONSORBLOCK_CATEGORIES = ["sponsor", "selfpromo", "interaction"]
-_VCODEC_SORT = {"h264": "vcodec:h264", "vp9": "vcodec:vp9", "av1": "vcodec:av01"}
 
 
 def normalize(spec: dict) -> dict:
@@ -76,6 +81,18 @@ def normalize(spec: dict) -> dict:
     # Audio-only files can't embed subtitles/thumbnails as video; keep the flags meaningful.
     if s["mode"] == "a":
         s["embed_subs"] = False
+    # Browser-playability guarantee (E7): the Download module exists to download → share → PLAY
+    # in-browser, so every output must play in EVERY browser, iOS/Safari/WebKit included. The only
+    # universally-safe combo is mp4 + H.264 + AAC/MP3, so we CLAMP the spec to it HERE — the single
+    # point every path (picker, stored profile, raw API) flows through — instead of only hiding
+    # options in the UI. Non-mp4 containers (mkv doesn't play at all; webm/VP9/AV1 fail iOS) and any
+    # explicit vcodec are coerced to the compat profile; Opus audio (Safari-flaky as a bare file)
+    # falls back to AAC/m4a. A source that exposes no H.264 is still caught by the worker's
+    # browser-safe re-encode (`_ensure_browser_playable`), so playback is guaranteed end-to-end.
+    s["container"] = "mp4"
+    s["vcodec"] = None
+    if s["audio_format"] not in ("m4a", "mp3"):
+        s["audio_format"] = "m4a"
     return s
 
 
@@ -98,12 +115,17 @@ def build_ydl_opts(
     outtmpl: str,
     progress_hook,
     extra: dict | None = None,
+    cookiefile: str | None = None,
 ) -> dict:
     """Assemble yt-dlp options for a single download to `outtmpl` (a full path template).
 
     `extra` is source-specific options contributed by the SourceAdapter (e.g. YouTube's
     `extractor_args` with the player-client set + bgutil PO-token base_url); it is merged onto the
-    generic options below. Everything here is source-agnostic."""
+    generic options below. Everything here is source-agnostic.
+
+    `cookiefile` is the acting user's per-host cookies.txt path (S6), attached ONLY by the worker
+    after the host-scope + private-asset gate in `downloads.credentials`. It is set AFTER the `extra`
+    merge so a source adapter can never clobber it."""
     s = normalize(spec)
     h = s["max_height"]
     opts: dict = {
@@ -132,6 +154,11 @@ def build_ydl_opts(
     if extra:
         opts.update(extra)
 
+    # The acting user's per-host cookie (S6). AFTER the adapter merge on purpose: an adapter must not
+    # be able to override the authenticated session the worker resolved for this specific user.
+    if cookiefile:
+        opts["cookiefile"] = cookiefile
+
     if s["mode"] == "a":
         opts["format"] = "bestaudio/best"
         opts["postprocessors"].append(
@@ -143,51 +170,33 @@ def build_ydl_opts(
         )
     else:
         hcap = f"[height<=?{h}]" if h else ""
-        # Compatibility-first for mp4 (the universal container): produce H.264 video + AAC audio
-        # so shared/downloaded files play in EVERY browser, including iOS/Safari. WebKit (which
-        # every iOS browser, Brave included, is forced to use) decodes only H.264/H.265 + AAC
-        # inside mp4 — a VP9/AV1-in-mp4 file shows a broken player there, even though Chromium
-        # plays it fine. A custom profile that explicitly sets `vcodec` opts out.
-        compat = s["container"] == "mp4" and s["vcodec"] is None
+        # Every video download is the mp4/H.264 compat profile (normalize() clamps container→mp4,
+        # vcodec→None), so shared/downloaded files play in EVERY browser, iOS/Safari included. WebKit
+        # (which every iOS browser, Brave included, is forced to use) decodes only H.264/H.265 + AAC
+        # inside mp4 — a VP9/AV1-in-mp4 file shows a broken player there — so H.264 is selected at the
+        # SELECTION level, not merely preferred: a sort key can't conjure an H.264 stream a source
+        # doesn't expose as video-only. A source that ships only non-H.264 is caught after download by
+        # the worker's browser-safe re-encode (`_ensure_browser_playable`).
         if s["mode"] == "v":
-            if compat:
-                # Video-only: keep it audio-free. Prefer an H.264 *video-only* stream, then any
-                # video-only, and only fall to a progressive (audio-bearing) `best` as a last
-                # resort — same audio-free-when-possible guarantee as the old `bestvideo/best`.
-                opts["format"] = (
-                    f"bestvideo[vcodec^=avc1]{hcap}/bestvideo{hcap}"
-                    f"/best[vcodec^=avc1]{hcap}/best{hcap}"
-                )
-            else:
-                opts["format"] = f"bestvideo{hcap}/best{hcap}"
+            # Video-only: keep it audio-free. Prefer an H.264 video-only stream, then any video-only,
+            # and only fall to a progressive (audio-bearing) `best` as a last resort.
+            opts["format"] = (
+                f"bestvideo[vcodec^=avc1]{hcap}/bestvideo{hcap}/best[vcodec^=avc1]{hcap}/best{hcap}"
+            )
         else:  # av
-            if compat:
-                # Prefer H.264 at the SELECTION level, not just via format_sort: a sort key is only
-                # a *preference* and can't conjure an H.264 stream a source doesn't expose as
-                # video-only. A non-YouTube source (e.g. Facebook) may ship AV1 as the best
-                # video-only stream and H.264 only as a *progressive* (a+v) format — which
-                # `bestvideo` skips — so `bestvideo+bestaudio` picked AV1 and iOS broke. This chain
-                # tries avc1 video-only, then the avc1 progressive, then anything.
-                opts["format"] = (
-                    f"bestvideo[vcodec^=avc1]{hcap}+bestaudio[acodec^=mp4a]"
-                    f"/best[vcodec^=avc1]{hcap}"
-                    f"/bestvideo{hcap}+bestaudio/best{hcap}"
-                )
-            else:
-                opts["format"] = f"bestvideo{hcap}+bestaudio/best{hcap}"
-        if s["container"]:
-            opts["merge_output_format"] = s["container"]
-        sort = []
-        # Keep the codec preference as a tiebreaker (ranks H.264/AAC above resolution among the
-        # selected candidates); the selector above is the hard guarantee, this is belt-and-braces.
-        if compat:
-            sort += ["vcodec:h264", "acodec:aac"]
+            # avc1 video-only + m4a audio, then the avc1 progressive, then anything (re-encoded).
+            opts["format"] = (
+                f"bestvideo[vcodec^=avc1]{hcap}+bestaudio[acodec^=mp4a]"
+                f"/best[vcodec^=avc1]{hcap}"
+                f"/bestvideo{hcap}+bestaudio/best{hcap}"
+            )
+        opts["merge_output_format"] = "mp4"
+        # Codec preference tiebreaker (ranks H.264/AAC among the selected candidates); the selector
+        # above is the hard guarantee, this is belt-and-braces.
+        sort = ["vcodec:h264", "acodec:aac"]
         if h:
             sort.append(f"res:{h}")
-        if s["vcodec"] in _VCODEC_SORT:
-            sort.append(_VCODEC_SORT[s["vcodec"]])
-        if sort:
-            opts["format_sort"] = sort
+        opts["format_sort"] = sort
 
     # SponsorBlock first (marks segments), then strip them from the media + chapters.
     if s["sponsorblock"]:

backend/app/downloads/gc.py

@@ -86,11 +86,25 @@ def _sweep_orphan_files(db: Session, download_root: str) -> int:
 
     cutoff = time.time() - _ORPHAN_MIN_AGE_S
     removed = 0
+    # Throttle the whole-tree walk: this runs in the API process, and an unpaced rglob+stat over a
+    # large download root monopolizes disk IO long enough to make web requests + playback stutter.
+    # Yield the IO channel after every `batch` files touched so foreground work interleaves.
+    pause_s = max(0, settings.download_gc_sweep_pause_ms) / 1000.0
+    batch = max(1, settings.download_gc_sweep_batch)
+    touched = 0
+
+    def _throttle() -> None:
+        nonlocal touched
+        touched += 1
+        if pause_s and touched % batch == 0:
+            time.sleep(pause_s)
+
     for entry in root.iterdir():
         if entry.name.startswith("."):  # .edits / .plex-* / .staging / .storyboards + any dotfile
             continue
         files = [entry] if entry.is_file() else [p for p in entry.rglob("*") if p.is_file()]
         for f in files:
+            _throttle()
             try:
                 if f.resolve() in keep or f.stat().st_mtime > cutoff:
                     continue

backend/app/downloads/links.py

@@ -80,9 +80,13 @@ def public_meta(
 
     Resolves the owner's per-download display overrides (custom title/channel) over the asset's
     auto-extracted values, and surfaces the source + any extra reference links as clickable URLs."""
-    from app.downloads import service
+    from app.downloads import mediakind, service
 
     source_url = service.reference_url(job, asset)
+    # Audio-only assets (mp3 rips, extracted audio) can't play inside a <video> element on WebKit
+    # (all iOS browsers), so the watch page renders a native <audio> instead. A generic uploaded
+    # file (media_kind='file') has no player at all — the watch page shows file info + a download.
+    # Both branches read the stored media_kind (the single source), not a re-derived codec check.
     return {
         "title": (job and job.display_name) or asset.title,
         "uploader": (job and job.display_uploader) or asset.uploader,
@@ -92,6 +96,10 @@ def public_meta(
         "duration_s": asset.duration_s,
         "width": asset.width,
         "height": asset.height,
+        "audio": asset.media_kind == mediakind.AUDIO,
+        "media_kind": asset.media_kind,
+        "size_bytes": asset.size_bytes,
+        "container": asset.container,
         "allow_download": link.allow_download,
         "file_url": file_url,
         "poster_url": poster_url,

backend/app/downloads/mediakind.py

@@ -0,0 +1,23 @@
+"""The media-kind discriminator for a library asset — the single home of one invariant.
+
+`MediaAsset.media_kind` is `"video" | "audio" | "file"`. It decides which library actions apply:
+media (video/audio) gets play/edit/share; a generic uploaded file gets download + share only, and
+is never rendered inline (see the force-download serving in the file/watch routes). Every finalize
+path computes it HERE — the download worker + the upload ingest via `derive`, the editor by
+carrying the source's kind over — so the rule lives in code, not in a comment that can drift (an
+earlier ad-hoc `vcodec is None and acodec is not None` audio check lived only in links.py).
+"""
+
+VIDEO = "video"
+AUDIO = "audio"
+FILE = "file"
+
+
+def derive(vcodec: str | None, acodec: str | None) -> str:
+    """Media kind from the probed codecs: a video stream -> video, audio-only -> audio, neither
+    (a non-media upload: pdf/zip/docx/…) -> file."""
+    if vcodec:
+        return VIDEO
+    if acodec:
+        return AUDIO
+    return FILE

backend/app/downloads/pipeline.py

@@ -8,13 +8,14 @@ from datetime import date, datetime, timedelta, timezone
 from pathlib import Path
 
 import yt_dlp
+from sqlalchemy import select
 
 from app import sysconfig
 from app.config import settings
 from app.db import SessionLocal
 from app.downloads import edit as editmod
 from app.downloads import errors as dlerrors
-from app.downloads import adapters, formats, service, storage
+from app.downloads import adapters, credentials, formats, mediakind, probe, service, storage
 from app.downloads.jobdb import (
     _edit_staging_dir,
     _job_status,
@@ -304,10 +305,13 @@ def _media_info(info: dict) -> dict:
     return {**info, **chosen}
 
 
-def _extract_with_fallback(job_id, asset_id, url, spec, staging, adapter):
+def _extract_with_fallback(job_id, asset_id, url, spec, staging, adapter, cookiefile=None):
     """Download via yt-dlp using the source `adapter`'s client sets + options. For YouTube the adapter
     supplies the primary player-client set then a POT-backed fallback (retried on a bot/DRM/format
-    error); other sources make a single attempt. Returns the info dict of the successful attempt."""
+    error); other sources make a single attempt. Returns the info dict of the successful attempt.
+
+    `cookiefile` (S6) is the acting user's per-host cookies.txt, already gated by
+    `credentials.resolve_cookiefile`; passed to every attempt so the fallback stays authenticated."""
     client_sets = adapter.client_sets()
     outtmpl = str(staging / "%(id)s.%(ext)s")
     last_exc: Exception | None = None
@@ -317,6 +321,7 @@ def _extract_with_fallback(job_id, asset_id, url, spec, staging, adapter):
             outtmpl,
             _make_progress_hook(job_id, asset_id),
             extra=adapter.ydl_opts_extra(clients),
+            cookiefile=cookiefile,
         )
         opts["postprocessor_hooks"] = [_make_pp_hook(job_id)]
         _touch_job(job_id)  # stall-watchdog heartbeat: extraction writes no progress, so a slow /
@@ -381,7 +386,9 @@ def _ensure_browser_playable(job_id: int, produced: Path, spec: dict, info: dict
     # re-encode still shows real progress instead of a frozen 0%.
     total_s = int(info["duration"]) if info.get("duration") else editmod.probe_duration(produced)
     editmod.run_ffmpeg(
-        editmod.build_browser_safe_cmd(produced, dest, reenc_v, reenc_a),
+        editmod.build_browser_safe_cmd(
+            produced, dest, reenc_v, reenc_a, threads=editmod.encode_thread_cap()
+        ),
         total_s=total_s,
         on_progress=_ffmpeg_progress_writer(job_id, "processing"),
         should_cancel=_cancel_poll(job_id),
@@ -395,8 +402,11 @@ def _ensure_browser_playable(job_id: int, produced: Path, spec: dict, info: dict
     return dest
 
 
-def _download(job_id: int, asset_id: int, source_kind: str, source_ref: str, spec: dict) -> None:
+def _download(
+    job_id: int, asset_id: int, source_kind: str, source_ref: str, spec: dict, user_id: int
+) -> None:
     staging = _staging_dir(asset_id)
+    cookiefile: Path | None = None
     try:
         if staging.exists():
             shutil.rmtree(staging, ignore_errors=True)
@@ -405,7 +415,27 @@ def _download(job_id: int, asset_id: int, source_kind: str, source_ref: str, spe
         _set_job(job_id, phase="downloading", progress=0)
         adapter = adapters.resolve_adapter(source_kind, source_ref)
         url = service.source_url(source_kind, source_ref)
-        info = _media_info(_extract_with_fallback(job_id, asset_id, url, spec, staging, adapter))
+        # S6: attach the acting user's per-host cookie ONLY when it's host-scoped to this URL AND
+        # this asset is that user's private, salted identity (the double gate lives in credentials).
+        with SessionLocal() as cdb:
+            asset_sig = cdb.execute(
+                select(MediaAsset.format_sig).where(MediaAsset.id == asset_id)
+            ).scalar_one_or_none()
+            if asset_sig is not None:
+                cookiefile = credentials.resolve_cookiefile(
+                    cdb, user_id, url, asset_sig, spec, staging
+                )
+        info = _media_info(
+            _extract_with_fallback(
+                job_id,
+                asset_id,
+                url,
+                spec,
+                staging,
+                adapter,
+                cookiefile=str(cookiefile) if cookiefile else None,
+            )
+        )
         # Re-resolve now that yt-dlp's info reveals the true source (a bare/redirected url only
         # identifies post-extraction) so the .nfo uniqueid type + uploader_url agree on one source.
         adapter = adapters.resolve_adapter(source_kind, source_ref, info)
@@ -445,15 +475,15 @@ def _download(job_id: int, asset_id: int, source_kind: str, source_ref: str, spe
                 asset.rel_path = rel
                 asset.size_bytes = size
                 asset.duration_s = meta.duration_s
-                asset.width = int(info["width"]) if info.get("width") else None
-                asset.height = int(info["height"]) if info.get("height") else None
+                # Codecs/dims come from a PROBE of the finished file — the ground truth — NOT yt-dlp's
+                # `info` dict, whose codec fields are absent for some sources (Facebook among them):
+                # deriving media_kind from those nulls misclassified a real H.264 video as a
+                # download-only 'file' with no in-app play/edit. Same probe the upload ingest uses.
+                asset.vcodec, asset.acodec, asset.width, asset.height = probe.resolve_media_facts(
+                    final, info
+                )
                 asset.container = ext
-                asset.vcodec = (
-                    info.get("vcodec") if info.get("vcodec") not in (None, "none") else None
-                )
-                asset.acodec = (
-                    info.get("acodec") if info.get("acodec") not in (None, "none") else None
-                )
+                asset.media_kind = mediakind.derive(asset.vcodec, asset.acodec)
                 asset.title = meta.title
                 asset.uploader = meta.uploader
                 asset.uploader_url = adapter.uploader_url(info)
@@ -515,6 +545,10 @@ def _download(job_id: int, asset_id: int, source_kind: str, source_ref: str, spe
             db.commit()
         log.warning("job %s failed: %s", job_id, msg)
     finally:
+        # Unlink the decrypted cookie file explicitly (the rmtree below removes the whole staging
+        # tree too, but never leave a plaintext session cookie on disk a moment longer than needed).
+        if cookiefile is not None:
+            cookiefile.unlink(missing_ok=True)
         shutil.rmtree(staging, ignore_errors=True)
 
 

backend/app/downloads/probe.py

@@ -0,0 +1,107 @@
+"""Ground-truth media probe for a produced library file — the SINGLE place both ingest paths ask
+"what is actually on disk?".
+
+`media_kind` (and the stored `vcodec`/`acodec`/`width`/`height`) must reflect the real file, not an
+extractor's metadata: yt-dlp's `info` dict omits codec fields for some sources (e.g. Facebook), and
+deriving the kind from those nulls misclassified a genuine H.264 video as a download-only `file`
+(no in-app play). So the download worker (`pipeline`) and the local upload ingest (`upload`) both
+probe the finished file here; `mediakind.derive` then turns the probed codecs into the kind.
+"""
+
+from pathlib import Path
+
+from app.downloads import edit as editmod
+
+# ffprobe container formats that mean "this is a still image / image sequence", NOT playable media.
+# A standalone jpg/png/gif/webp/bmp reports a real video stream (codec mjpeg/png/…) with no
+# `attached_pic` flag, so without this guard it would classify as media_kind='video' and get a Play
+# button + a broken in-app <video> player (and inline serving on the public share). Keyed on the
+# container format so an animated gif/webp also lands as a generic 'file' (no browser plays those in
+# a <video> either). SVG and anything else ffprobe can't decode already fails the probe → 'file'.
+_IMAGE_FORMATS = {
+    "image2",
+    "image2pipe",
+    "png_pipe",
+    "mjpeg",
+    "mjpeg_pipe",
+    "jpeg_pipe",
+    "gif",
+    "webp_pipe",
+    "bmp_pipe",
+    "tiff_pipe",
+    "ico",
+    "svg_pipe",
+}
+
+
+def _facts_from_probe(
+    data: dict,
+) -> tuple[str | None, str | None, int | None, int | None, int | None]:
+    """(vcodec, acodec, width, height, duration_s) parsed from a NON-None ffprobe JSON dict. A still
+    image / image-sequence container yields no vcodec (→ generic 'file'); a video stream flagged
+    `attached_pic` (embedded cover art in an mp3/m4a) is skipped — it's a thumbnail, not a real video
+    track, so an audio file with album art still classifies as audio."""
+    fmt = data.get("format") or {}
+    fmt_names = {n.strip() for n in (fmt.get("format_name") or "").split(",")}
+    if fmt_names & _IMAGE_FORMATS:
+        return None, None, None, None, None
+
+    vcodec = acodec = None
+    width = height = None
+    for stream in data.get("streams", []):
+        kind = stream.get("codec_type")
+        if kind == "video" and vcodec is None:
+            if (stream.get("disposition") or {}).get("attached_pic"):
+                continue  # cover art, not a video track
+            vcodec = stream.get("codec_name")
+            width = stream.get("width")
+            height = stream.get("height")
+        elif kind == "audio" and acodec is None:
+            acodec = stream.get("codec_name")
+
+    duration = None
+    try:
+        raw = fmt.get("duration")
+        if raw is not None:
+            duration = int(float(raw))
+    except (TypeError, ValueError):
+        duration = None
+    return vcodec, acodec, width, height, duration
+
+
+def probe_media(path: Path) -> tuple[str | None, str | None, int | None, int | None, int | None]:
+    """(vcodec, acodec, width, height, duration_s) from one ffprobe call; all None if ffprobe fails
+    or the file isn't playable media (an unprobeable file — or a still image — is treated as a generic
+    non-media file, so it becomes a download-only 'file' rather than a broken 'video')."""
+    data = editmod.run_ffprobe_json(path, show_streams=True, show_format=True)
+    if data is None:
+        return None, None, None, None, None
+    return _facts_from_probe(data)
+
+
+def resolve_media_facts(
+    path: Path, info: dict
+) -> tuple[str | None, str | None, int | None, int | None]:
+    """(vcodec, acodec, width, height) for the stored download asset: PROBE the finished file on disk
+    (the ground truth). yt-dlp's `info` omits codec/dimension fields for some sources (Facebook among
+    them), so deriving media_kind from it there labelled a real H.264 video a download-only 'file'.
+
+    Precedence is by whether the probe RAN, not per-field: if ffprobe read the file, its codec verdict
+    is authoritative — INCLUDING a deliberate None (cover-art-only audio, a still image). A per-field
+    `probe or info` fallback would let `info`'s stale vcodec resurrect a video track the file doesn't
+    have (yt-dlp reports a progressive `vcodec` for an audio-mode download whose video it then strips),
+    mislabelling an audio download as a broken in-app 'video'. Only when ffprobe could NOT read the
+    file at all do we fall back to `info` (the pre-probe behaviour, a safety net); the cosmetic
+    dimensions still gap-fill from `info` in either case."""
+    data = editmod.run_ffprobe_json(path, show_streams=True, show_format=True)
+    info_v = info.get("vcodec") if info.get("vcodec") not in (None, "none") else None
+    info_a = info.get("acodec") if info.get("acodec") not in (None, "none") else None
+    info_w = int(info["width"]) if info.get("width") else None
+    info_h = int(info["height"]) if info.get("height") else None
+    if data is None:
+        # ffprobe could not read the file — fall back to the extractor's info entirely.
+        return info_v, info_a, info_w, info_h
+    pv, pa, pw, ph, _dur = _facts_from_probe(data)
+    # Probe ran → its codecs win outright (a None means "no such track", not "unknown"); info only
+    # gap-fills the cosmetic width/height the probe couldn't read.
+    return pv, pa, pw if pw is not None else info_w, ph if ph is not None else info_h

backend/app/downloads/quota.py

@@ -122,6 +122,22 @@ def check_enqueue(db: Session, user_id: int) -> None:
         raise QuotaExceeded("max_bytes", lim.max_bytes, used)
 
 
+def check_upload(db: Session, user_id: int, add_bytes: int) -> None:
+    """Like check_enqueue, but for an upload whose size is KNOWN at ingest: also reject when adding
+    this file would push the footprint over max_bytes. A download can't pre-check its size (unknown
+    until the worker finishes) so check_enqueue only compares the current footprint; an upload can,
+    so it's charged against the cap before it lands. Raises QuotaExceeded(max_jobs|max_bytes)."""
+    lim = resolve(db, user_id)
+    if lim.unlimited:
+        return
+    n = active_jobs(db, user_id)
+    if n >= lim.max_jobs:
+        raise QuotaExceeded("max_jobs", lim.max_jobs, n)
+    projected = footprint(db, user_id) + add_bytes
+    if projected > lim.max_bytes:
+        raise QuotaExceeded("max_bytes", lim.max_bytes, projected)
+
+
 def usage(db: Session, user_id: int) -> dict:
     """Compact usage snapshot for the UI (footprint + counts vs limits)."""
     lim = resolve(db, user_id)

backend/app/downloads/runner.py

@@ -12,16 +12,48 @@ progress hook), then exits 0. An unexpected crash exits non-zero and the parent
 """
 
 import logging
+import os
+import shutil
+import subprocess
 import sys
 
+from app.config import settings
 from app.db import SessionLocal
+from app.downloads import edit as editmod
 from app.models import DownloadJob
 
 log = logging.getLogger("siftlode.worker.runner")
 
 
+def _deprioritize() -> None:
+    """Lower THIS child's CPU + IO priority so its yt-dlp/ffmpeg work — every descendant inherits the
+    handicap — can never starve the co-located API, Postgres, or Plex playback. Run once at startup,
+    before any heavy work. Every step is best-effort: a failed renice must never fail a download."""
+    nice_inc = settings.download_child_nice
+    if nice_inc > 0:
+        try:
+            os.nice(nice_inc)  # relative increment; the child starts at the worker's nice (0)
+        except OSError as exc:
+            log.info("could not renice download child: %s", str(exc)[:120])
+    cls = settings.download_child_ionice_class
+    if cls > 0 and shutil.which("ionice"):  # util-linux; absent on some minimal images
+        try:
+            subprocess.run(
+                ["ionice", "-c", str(cls), "-p", str(os.getpid())],
+                capture_output=True,
+                timeout=5,
+                check=False,
+            )
+        except (OSError, subprocess.SubprocessError) as exc:
+            log.info("could not ionice download child: %s", str(exc)[:120])
+    # Cap OpenMP-parallel ffmpeg filters to the same budget as the encoder threads, so a filter
+    # graph can't fan out across every core behind ffmpeg's own `-threads` cap.
+    os.environ.setdefault("OMP_NUM_THREADS", str(editmod.encode_thread_cap()))
+
+
 def main() -> None:
     logging.basicConfig(level=logging.INFO)
+    _deprioritize()
     if len(sys.argv) != 2:
         print("usage: python -m app.downloads.runner <job_id>", file=sys.stderr)
         raise SystemExit(2)
@@ -35,6 +67,7 @@ def main() -> None:
         job_kind = job.job_kind
         spec = dict(job.profile_snapshot or {})
         source_kind, source_ref = job.source_kind, job.source_ref
+        user_id = job.user_id
     if asset_id is None:
         return
 
@@ -45,7 +78,7 @@ def main() -> None:
     if job_kind == "edit":
         _process_edit(job_id, asset_id)
     else:
-        _download(job_id, asset_id, source_kind, source_ref, spec)
+        _download(job_id, asset_id, source_kind, source_ref, spec, user_id)
 
 
 if __name__ == "__main__":

backend/app/downloads/service.py

@@ -15,8 +15,9 @@ from sqlalchemy.orm import Session
 
 from app.config import settings
 from app.downloads import adapters
+from app.downloads import credentials
 from app.downloads import edit as editmod
-from app.downloads import formats, quota, storage
+from app.downloads import formats, mediakind, quota, storage
 from app.downloads.status import HOLDING, JobStatus
 from app.models import Channel, DownloadJob, MediaAsset, Video
 
@@ -155,7 +156,12 @@ def enqueue(
     Raises quota.QuotaExceeded if the user is at their job-count or footprint cap."""
     quota.check_enqueue(db, user_id)
     spec = formats.normalize(spec)
-    sig = formats.format_sig(spec)
+    # If this user has a stored cookie for the download's host, salt the cache signature with their
+    # id so the cookie-authed result is a PRIVATE asset — never dedup-shared with, or cache-served
+    # to, another user (the load-bearing privacy fix; the worker attaches the cookie to exactly this
+    # salted identity). A normal download (no matching cookie) gets salt=None and shares as before.
+    salt = credentials.salt_for_enqueue(db, user_id, source_url(source_kind, source_ref))
+    sig = formats.format_sig(spec, salt=salt)
     asset = get_or_create_asset(db, source_kind, source_ref, sig)
     # Show a real title + thumbnail the moment it's queued (feed downloads are catalog videos).
     populate_from_catalog(db, asset)
@@ -210,6 +216,10 @@ def enqueue_edit(
     src_asset = db.get(MediaAsset, source_job.asset_id) if source_job.asset_id else None
     if src_asset is None or src_asset.status != "ready" or not src_asset.rel_path:
         raise EditError("source_not_ready")
+    # A generic uploaded file (media_kind='file') has no timeline to trim/crop — the editor path is
+    # media-only. Reject here so an upload's file never reaches the ffmpeg edit worker.
+    if src_asset.media_kind == mediakind.FILE:
+        raise EditError("not_media")
 
     spec = editmod.normalize_edit_spec(edit_spec)
     if not spec:
@@ -226,6 +236,9 @@ def enqueue_edit(
         asset.thumbnail_url = src_asset.thumbnail_url
         asset.upload_date = src_asset.upload_date
         asset.duration_s = editmod.clip_duration(spec, src_asset.duration_s)
+        # A clip inherits its source's kind (a video edit stays video, an audio trim stays audio);
+        # the ffmpeg edit worker doesn't re-probe codecs, so set it here where the source is known.
+        asset.media_kind = src_asset.media_kind or mediakind.VIDEO
 
     job = DownloadJob(
         user_id=user_id,

backend/app/downloads/storage.py

@@ -19,6 +19,8 @@ from datetime import date
 from pathlib import Path
 from xml.sax.saxutils import escape
 
+from app.downloads import mediakind
+
 # Reserve room for the "_id.ext" suffix + parent dirs within the 255-char component limit.
 _MAX_TITLE = 120
 # User-facing (Content-Disposition) names can be longer than an on-disk component.
@@ -147,6 +149,81 @@ def edit_rel_path(user_id: int, asset_id: int, ext: str) -> str:
     return f".edits/{user_id}/clip_{asset_id}.{ext}"
 
 
+def _clean_upload_ext(filename: str) -> str:
+    """The upload's extension reduced to a shell-safe, lowercased, bounded token (``""`` when the
+    upload has no extension). The SINGLE definition feeding both the on-disk suffix and the stored
+    `container` — they must agree (the served Content-Disposition suffix has to match the container),
+    so the sanitize/truncation rule lives in one place, not two drifting copies."""
+    return _UNSAFE.sub("", Path(filename).suffix.lstrip(".")).lower()[:16]
+
+
+def upload_rel_path(user_id: int, asset_id: int, filename: str) -> str:
+    """On-disk path (relative to DOWNLOAD_ROOT) for a locally-uploaded file.
+
+    Kept in a per-user `.uploads/` tree — device-downloadable via the file endpoint, but NOT part of
+    the Plex library (an upload is arbitrary user content, not a canonical episode; no .nfo/poster
+    episode sidecars). The name is system-decided and bound to the asset id (`_a{id}` keeps two
+    same-named uploads apart); the original filename is display metadata only. The extension is
+    preserved (shell-safe, bounded) so the served file + its Content-Disposition carry a correct
+    suffix; an extensionless upload stays extensionless."""
+    stem = sanitize(Path(filename).stem, 80)
+    ext = _clean_upload_ext(filename)
+    suffix = f".{ext}" if ext else ""
+    return f".uploads/{user_id}/{stem}_a{asset_id}{suffix}"
+
+
+def upload_ext(filename: str) -> str | None:
+    """The stored `container` for an uploaded file: its shell-safe lowercased extension, or None when
+    the upload has no extension (a bare name). Shares `_clean_upload_ext` with `upload_rel_path` so the
+    stored container and the on-disk suffix can never diverge."""
+    return _clean_upload_ext(filename) or None
+
+
+# The Content-Type used to serve an inline-playable media asset, keyed by its stored `container`.
+# DELIBERATELY a strict allow-list of known audio/video containers: the served type is chosen from
+# the asset's ffprobe-verified media_kind + this table, NEVER guessed from the raw (user-controlled)
+# upload extension. Without this, an uploaded media/HTML polyglot named "evil.html" — a real MP3/MP4
+# that ffprobe classifies as media, so it dodges the generic-file force-download — would be served
+# with a Content-Type Starlette guesses from ".html" (text/html) and execute as stored XSS on the
+# serving origin. A media asset whose container isn't in this table falls back to a neutral
+# force-download attachment (see `served_media_type`), so nothing script-executable is ever inline.
+_MEDIA_MIME: dict[str, str] = {
+    # video containers
+    "mp4": "video/mp4",
+    "m4v": "video/mp4",
+    "mov": "video/quicktime",
+    "webm": "video/webm",
+    "mkv": "video/x-matroska",
+    "ogv": "video/ogg",
+    "avi": "video/x-msvideo",
+    # audio containers
+    "m4a": "audio/mp4",
+    "mp3": "audio/mpeg",
+    "aac": "audio/aac",
+    "ogg": "audio/ogg",
+    "oga": "audio/ogg",
+    "opus": "audio/ogg",
+    "weba": "audio/webm",
+    "wav": "audio/wav",
+    "flac": "audio/flac",
+}
+
+
+def served_media_type(media_kind: str | None, container: str | None) -> str | None:
+    """The Content-Type a library file MUST be served with — a real audio/video MIME for a recognised
+    media container, else ``None`` meaning "serve as a neutral force-download attachment".
+
+    Returns None for a generic ``file`` kind AND for any media whose container we don't positively
+    recognise as safe. Callers serve None as ``application/octet-stream`` + ``attachment`` so the
+    served Content-Type is NEVER derived from the (attacker-controlled) file extension — the guard
+    that stops uploaded HTML/SVG or a media/HTML polyglot from executing inline on the serving
+    origin. A ``None`` media_kind (a legacy asset before the discriminator was backfilled) is treated
+    as media so an old download keeps its inline player."""
+    if media_kind == mediakind.FILE:
+        return None
+    return _MEDIA_MIME.get((container or "").lower())
+
+
 def download_filename(display_name: str, container: str | None, path: Path) -> str:
     """The Content-Disposition filename for a served download: the cleaned display name carrying a single
     correct extension — the asset container, else the file's own suffix — without doubling it when the

backend/app/downloads/upload.py

@@ -0,0 +1,122 @@
+"""Local file ingest for the download center (E7 S5) — the non-yt-dlp path into the media library.
+
+A user-uploaded file joins the SAME library as a downloaded one, so it inherits the whole function
+set already built (metadata chips, share links, and — for media — in-app play/edit). Unlike a
+download it bypasses yt-dlp AND the worker entirely: the file is already on the host, so ingest
+probes it, places it on disk, and creates an already-`ready` MediaAsset + `done` DownloadJob in one
+step — the same "the file exists, mark it done now" shortcut `service.enqueue` takes on a cache hit.
+
+Kinds (the invariant lives in `mediakind`): a probe with a real video stream -> video, audio-only
+-> audio, neither -> a generic 'file' (pdf/zip/docx/…) that is download-only and never rendered
+inline (see the force-download serving in the file/watch routes). This module is the ingest seam a
+future sub-function (e.g. convert) plugs a new adapter into, mirroring how it sidesteps the worker.
+
+An upload does NOT get an `expires_at`: it's user-provided and may be irreplaceable (there's no
+source to re-download), so it doesn't age out on the retention clock the way a re-fetchable download
+does — it lives until the user deletes it.
+"""
+
+import secrets
+from datetime import datetime, timezone
+from pathlib import Path
+
+from sqlalchemy.orm import Session
+
+from app.config import settings
+from app.downloads import edit as editmod
+from app.downloads import mediakind, probe, quota, service, storage
+from app.models import DownloadJob, MediaAsset
+
+
+def _title_from_filename(filename: str) -> str:
+    """A human display title from the original upload name: the stem with separators tidied to
+    spaces (kept as-is otherwise — this is display metadata, not the shell-safe on-disk name)."""
+    stem = Path(filename).stem.replace("_", " ").replace(".", " ").strip()
+    return (stem or "Upload")[:255]
+
+
+def ingest_upload(
+    db: Session,
+    user_id: int,
+    *,
+    filename: str,
+    src_path: Path,
+    size: int,
+    display_name: str | None = None,
+) -> DownloadJob:
+    """Ingest an already-uploaded file at `src_path` into `user_id`'s library and return the `done`
+    job. `src_path` is MOVED into place on success (the caller stages it to a temp file first).
+
+    Raises quota.QuotaExceeded (holdings/footprint cap) — checked BEFORE any disk write, so a
+    rejected upload leaves nothing behind and the caller just cleans up its temp file."""
+    quota.check_upload(db, user_id, size)  # the file's size is known → charge it up front
+
+    vcodec, acodec, width, height, duration = probe.probe_media(src_path)
+    kind = mediakind.derive(vcodec, acodec)
+
+    # An upload never dedups (each file is its own asset): a random ref makes the cache key unique,
+    # so `format_sig` is a constant marker rather than a format hash.
+    ref = f"{user_id}:{secrets.token_hex(8)}"[:512]
+    asset = MediaAsset(
+        source_kind="upload", source_ref=ref, format_sig="upload", status="pending", ref_count=0
+    )
+    db.add(asset)
+    db.flush()  # need asset.id for the on-disk path
+
+    rel = storage.upload_rel_path(user_id, asset.id, filename)
+    storage.place_file(src_path, settings.download_root, rel)
+    # From here the file is on disk under `.uploads/`. If the transaction fails before it commits, the
+    # asset/job rows roll back but the placed file would be ORPHANED — nothing references it, the
+    # per-user delete path keys off asset.rel_path (which is gone), and the GC orphan sweep skips the
+    # dot-prefixed `.uploads/` tree. So roll back the on-disk side too on any failure.
+    try:
+        final = storage.abs_path(settings.download_root, rel)
+        actual_size = final.stat().st_size if final.exists() else size
+
+        asset.status = "ready"
+        asset.rel_path = rel
+        asset.size_bytes = actual_size
+        asset.container = storage.upload_ext(filename)
+        asset.vcodec = vcodec
+        asset.acodec = acodec
+        asset.width = width
+        asset.height = height
+        asset.duration_s = duration
+        asset.media_kind = kind
+        asset.title = (display_name or "").strip() or _title_from_filename(filename)
+        asset.last_access_at = datetime.now(timezone.utc)
+        # No expires_at — see the module docstring (an upload is irreplaceable, so it doesn't age out).
+        if kind == mediakind.VIDEO:
+            # A frame poster gives the library row a thumbnail + the share link an og:image. Audio has
+            # no frame and a generic file no player, so neither gets one. Best-effort (ffmpeg decodes
+            # server side even for a codec the browser can't play).
+            asset.poster_path = editmod.ensure_poster(asset, settings.download_root)
+
+        job = DownloadJob(
+            user_id=user_id,
+            asset_id=asset.id,
+            job_kind="upload",
+            source_kind="upload",
+            source_ref=ref,
+            profile_snapshot={},
+            display_name=(display_name or "").strip() or None,
+            status="done",
+            progress=100,
+            queue_pos=service.next_queue_pos(db),
+        )
+        db.add(job)
+        service.incr_ref_count(db, asset.id)
+        db.commit()
+    except Exception:
+        db.rollback()
+        # The rows are gone; remove the now-unreferenced file so no bytes leak. Clean the poster by its
+        # DETERMINISTIC path (rel with a .jpg suffix, the same path ensure_poster writes to) rather than
+        # ensure_poster's return value: it writes the frame directly to that path and returns None on an
+        # ffmpeg failure, so a partial poster can be on disk while the return is None — gating on the
+        # return would skip that orphan. unlink is missing_ok, so the poster path is a harmless no-op
+        # when none was generated (audio/file, or a video whose poster never started).
+        for leaked in (rel, str(Path(rel).with_suffix(".jpg"))):
+            storage.abs_path(settings.download_root, leaked).unlink(missing_ok=True)
+        raise
+    db.refresh(job)
+    return job

backend/app/email.py

@@ -3,36 +3,103 @@
 Gmail SMTP + App Password by default. Deliberately fail-soft: if SMTP isn't configured
 or a send errors, we log and return False so the caller can fall back to in-app
 notifications — email is never load-bearing for the app's core flow.
+
+Fail-soft must not mean invisible, though: every drop also leaves an in-app notice in the admins'
+inbox (see `_alert_admins`). An instance whose SMTP was never filled in silently swallows
+verification links, password resets and access-request notices, and the operator's first clue used
+to be a person telling them nothing arrived.
 """
 
+import html
 import logging
+import re
 import smtplib
 import ssl
 from email.message import EmailMessage
 from email.utils import formatdate
 
-from app import sysconfig
+from sqlalchemy import select
+from sqlalchemy.orm import Session
+
+from app import mailtext, sysconfig
 from app.config import settings
 from app.db import SessionLocal
+from app.models import User
+from app.notifications import create_notification
+from app.ratelimit import RateLimiter
 
 log = logging.getLogger("siftlode.email")
 
-
-def _smtp() -> dict:
-    """Effective SMTP config (admin DB override over env defaults). Opens its own short
-    session because email is often sent from a BackgroundTask, outside a request's db."""
-    with SessionLocal() as db:
-        return {
-            "host": sysconfig.get_str(db, "smtp_host"),
-            "port": sysconfig.get_int(db, "smtp_port"),
-            "user": sysconfig.get_str(db, "smtp_user"),
-            "password": sysconfig.get_str(db, "smtp_password"),
-            "from": sysconfig.get_str(db, "smtp_from"),
-        }
+# One admin notice an hour per reason. A relay that is down fails every send, and the inbox must
+# stay readable; the log keeps the full record either way.
+_alert_throttle = RateLimiter(max_events=1, window_seconds=3600)
 
 
-def email_enabled() -> bool:
-    c = _smtp()
+def _alert_admins(reason: str, subject: str, recipients: list[str]) -> None:
+    """Record an in-app notice that a message did NOT go out. Best effort in every direction: it
+    opens its own session (callers are often background tasks), swallows its own errors, and never
+    reports failure to the caller — this is the fallback path, it must not become a new way to
+    break a send."""
+    if not _alert_throttle.allow(reason):
+        return
+    try:
+        with SessionLocal() as db:
+            admins = (
+                db.execute(
+                    select(User.id).where(
+                        User.role == "admin",
+                        User.is_active.is_(True),
+                        User.is_suspended.is_(False),
+                    )
+                )
+                .scalars()
+                .all()
+            )
+            if not admins:
+                # Nothing was recorded, so don't let this cost the next hour of alerts on the very
+                # path whose job is to stop drops going unseen. Same on the failure branch below.
+                _alert_throttle.reset()
+                return
+            for uid in admins:
+                create_notification(
+                    db,
+                    user_id=uid,
+                    type="email_undelivered",
+                    # English fallback; the inbox renders a translated version from `data`.
+                    title="Email could not be sent",
+                    body=subject,
+                    data={"reason": reason, "subject": subject, "recipients": recipients},
+                    commit=False,
+                )
+            db.commit()
+    except Exception:
+        _alert_throttle.reset()
+        log.exception("Could not record the undelivered-email notice (%r)", subject)
+
+
+def _read_smtp(db: Session) -> dict:
+    return {
+        "host": sysconfig.get_str(db, "smtp_host"),
+        "port": sysconfig.get_int(db, "smtp_port"),
+        "user": sysconfig.get_str(db, "smtp_user"),
+        "password": sysconfig.get_str(db, "smtp_password"),
+        "from": sysconfig.get_str(db, "smtp_from"),
+    }
+
+
+def _smtp(db: Session | None = None) -> dict:
+    """Effective SMTP config (admin DB override over env defaults). Opens its own short session when
+    the caller has none, because email is usually sent from a BackgroundTask outside a request's db.
+    A caller that IS inside a request should pass its session: reading the password decrypts a Fernet
+    value, and /api/me polls this for every admin tab."""
+    if db is not None:
+        return _read_smtp(db)
+    with SessionLocal() as own:
+        return _read_smtp(own)
+
+
+def email_enabled(db: Session | None = None) -> bool:
+    c = _smtp(db)
     return bool(c["host"] and c["user"] and c["password"])
 
 
@@ -40,6 +107,48 @@ def _admin_contact() -> str | None:
     return next(iter(sorted(settings.admin_email_set)), None)
 
 
+# A bare URL in a text/plain mail is only clickable if the CLIENT decides to linkify it. Gmail,
+# Outlook and Apple Mail do; plenty of lighter web clients render the body verbatim and leave the
+# link as dead text — which, for a verification or password-reset mail, is the whole message. So
+# every mail also carries an HTML alternative built from the SAME plain body (below), rather than
+# per-template HTML that would have to be kept in sync with it.
+#
+# `[^\s<]` stops at whitespace and at the `<` of any following markup; the trailing-punctuation trim
+# keeps a sentence-final period out of the href. `;` and `:` are deliberately NOT trimmed — escaping
+# turns `&` into `&amp;`, so a query string can legitimately end in a semicolon.
+_URL_RE = re.compile(r"https?://[^\s<]+")
+
+
+def _html_body(text: str) -> str:
+    """Render a plain-text mail body as minimal HTML: escaped, blank-line-separated paragraphs, with
+    real links. Escaping happens FIRST and the linkifier then runs over the escaped text — bodies
+    interpolate untrusted values (a requester's email address, the operator contact), so no caller
+    can inject markup, and `&` inside a URL is already `&amp;` by the time it reaches the href, which
+    is what an HTML attribute wants anyway."""
+
+    def _anchor(m: re.Match[str]) -> str:
+        url = m.group(0)
+        trail = ""
+        while url and url[-1] in ".,!?)":
+            url, trail = url[:-1], url[-1] + trail
+        if not url:
+            return trail
+        return f'<a href="{url}">{url}</a>{trail}'
+
+    paragraphs = [p for p in html.escape(text).split("\n\n") if p.strip()]
+    rendered = "".join(
+        f"<p>{_URL_RE.sub(_anchor, p).replace(chr(10), '<br>')}</p>" for p in paragraphs
+    )
+    # Inline styles only — many clients drop <style> blocks. No images, no external CSS, no tracking:
+    # the HTML part exists to make the link clickable, not to become a template to maintain.
+    return (
+        '<html><body style="margin:0;padding:16px;font-family:system-ui,-apple-system,'
+        "'Segoe UI',sans-serif;font-size:15px;line-height:1.6\">"
+        f'<div style="max-width:560px">{rendered}</div>'
+        "</body></html>"
+    )
+
+
 def _send(to: list[str], subject: str, body: str, reply_to: str | None = None) -> bool:
     recipients = [e for e in to if e]
     if not recipients:
@@ -47,6 +156,7 @@ def _send(to: list[str], subject: str, body: str, reply_to: str | None = None) -
     c = _smtp()
     if not (c["host"] and c["user"] and c["password"]):
         log.info("SMTP not configured; skipping email %r to %s", subject, recipients)
+        _alert_admins("not_configured", subject, recipients)
         return False
     msg = EmailMessage()
     msg["Subject"] = subject
@@ -57,7 +167,10 @@ def _send(to: list[str], subject: str, body: str, reply_to: str | None = None) -
     msg["Date"] = formatdate(localtime=True)
     if reply_to:
         msg["Reply-To"] = reply_to
+    # text/plain stays the primary part (it is the source of truth, and a text-only client still
+    # gets the full message); the HTML alternative below is what makes the link clickable everywhere.
     msg.set_content(body)
+    msg.add_alternative(_html_body(body), subtype="html")
     try:
         with smtplib.SMTP(c["host"], c["port"], timeout=20) as s:
             s.starttls(context=ssl.create_default_context())
@@ -67,128 +180,153 @@ def _send(to: list[str], subject: str, body: str, reply_to: str | None = None) -
         return True
     except Exception:
         log.exception("SMTP send failed (%r to %s)", subject, recipients)
+        _alert_admins("send_failed", subject, recipients)
         return False
 
 
-def send_access_approved(email: str) -> bool:
+def _next_step(verify_link: str | None, has_account: bool, hours: int, lang: str) -> str:
+    """What this person actually has to do next, in the one paragraph that carries the whole flow.
+
+    Three states, because a mail that guesses wrong sends someone looking for a link that isn't
+    coming — or worse, tells them to sign in when their address is still unconfirmed and sign-in will
+    refuse them (E9.5 S4 named that state on screen; the mail must not contradict it).
+
+    The link branch is the point of the C option: in the common ordering — approve first, the person
+    signs up later, or signs up and waits — they would otherwise have to find and open TWO separate
+    messages. One mail, one click.
+    """
+    if verify_link:
+        return mailtext.text(
+            "next_step.verify", lang, link=verify_link, expiry=mailtext.link_expiry(hours, lang)
+        )
+    if has_account:
+        return mailtext.text("next_step.sign_in", lang, app=settings.app_base)
+    return mailtext.text("next_step.register", lang, app=settings.app_base)
+
+
+def _reply_contact(lang: str) -> tuple[str | None, str]:
+    """The admin address to answer to, and the closing line that names it — empty when no admin
+    contact is configured, so the mail never promises a reply nobody will read."""
     admin = _admin_contact()
-    body = (
-        "Hi,\n\n"
-        "Your request to use Siftlode has been approved — welcome aboard.\n\n"
-        "Open Siftlode and sign in, and your YouTube subscriptions feed will be ready:\n\n"
-        f"{settings.app_base}\n\n"
-        "If you weren't expecting this, you can ignore the message.\n\n"
-        "— Siftlode" + (f"\n\nQuestions? Just reply to this email ({admin})." if admin else "")
+    return admin, (mailtext.text("contact.reply", lang, admin=admin) if admin else "")
+
+
+def send_access_approved(
+    email: str,
+    lang: str,
+    verify_link: str | None = None,
+    has_account: bool = False,
+    hours: int = 24,
+) -> bool:
+    """Answer someone who ASKED for access. Sent automatically on approval, because a person who
+    made a request is owed a reply — unlike the admin-initiated invitation below."""
+    admin, contact = _reply_contact(lang)
+    body = mailtext.text(
+        "access_approved.body",
+        lang,
+        next_step=_next_step(verify_link, has_account, hours, lang),
+        contact=contact,
     )
-    return _send([email], "You're in — your Siftlode access is approved", body, reply_to=admin)
+    return _send([email], mailtext.text("access_approved.subject", lang), body, reply_to=admin)
 
 
-def send_access_denied(email: str) -> bool:
-    admin = _admin_contact()
-    body = (
-        "Hi,\n\n"
-        "Thanks for your interest in Siftlode. After review, your access request wasn't approved "
-        "this time.\n\n"
-        "If you think this was a mistake, you're welcome to reply and let us know.\n\n"
-        "— Siftlode" + (f"\n\nQuestions? Just reply to this email ({admin})." if admin else "")
+def send_access_invitation(
+    email: str,
+    lang: str,
+    verify_link: str | None = None,
+    has_account: bool = False,
+    hours: int = 24,
+) -> bool:
+    """Invite someone the admin let in WITHOUT them asking — sent only when the admin presses send.
+
+    Whitelisting an address is opening a door, not knocking on one: the operator has usually already
+    agreed it with the person, and an address can sit approved for weeks without anyone registering.
+    So adding to the whitelist stays silent and this is a separate, deliberate act. That is also why
+    the closing line offers no deadline — nudging is the one thing this mail must not do.
+
+    Its language is the one place the app has no signal to read: the admin typed this address in, so
+    nobody has ever told us how to address its owner. That is why the send button asks (E9.5 S7).
+    """
+    admin, contact = _reply_contact(lang)
+    body = mailtext.text(
+        "access_invitation.body",
+        lang,
+        next_step=_next_step(verify_link, has_account, hours, lang),
+        contact=contact,
     )
-    return _send([email], "About your Siftlode access request", body, reply_to=admin)
+    return _send([email], mailtext.text("access_invitation.subject", lang), body, reply_to=admin)
 
 
-def send_role_changed(to: str, role: str, operator: str | None) -> bool:
-    line = (
-        "You've been granted admin access on Siftlode — you can now manage settings, the "
-        "scheduler and users."
-        if role == "admin"
-        else "Your admin access on Siftlode has been removed — you're now a regular user."
+def send_access_denied(email: str, lang: str) -> bool:
+    admin, contact = _reply_contact(lang)
+    body = mailtext.text("access_denied.body", lang, contact=contact)
+    return _send([email], mailtext.text("access_denied.subject", lang), body, reply_to=admin)
+
+
+def send_role_changed(to: str, lang: str, role: str, operator: str | None) -> bool:
+    line = mailtext.text(
+        "role_changed.granted" if role == "admin" else "role_changed.revoked", lang
     )
-    contact = f"\n\nQuestions? Contact the operator at {operator}." if operator else ""
-    body = "Hi,\n\n" + line + contact + "\n\n— Siftlode"
-    return _send([to], "Your Siftlode role has changed", body, reply_to=operator)
+    contact = mailtext.text("contact.operator", lang, operator=operator) if operator else ""
+    body = mailtext.text("role_changed.body", lang, line=line, contact=contact)
+    return _send([to], mailtext.text("role_changed.subject", lang), body, reply_to=operator)
 
 
-def send_account_unsuspended(to: str, operator: str | None) -> bool:
-    contact = f"\n\nQuestions? Contact the operator at {operator}." if operator else ""
-    body = (
-        "Hi,\n\n"
-        "Your Siftlode account has been reinstated — the suspension was lifted and you can sign "
-        "in again." + contact + "\n\n— Siftlode"
-    )
-    return _send([to], "Your Siftlode account has been reinstated", body, reply_to=operator)
+def send_account_unsuspended(to: str, lang: str, operator: str | None) -> bool:
+    contact = mailtext.text("contact.operator", lang, operator=operator) if operator else ""
+    body = mailtext.text("account_unsuspended.body", lang, contact=contact)
+    return _send([to], mailtext.text("account_unsuspended.subject", lang), body, reply_to=operator)
 
 
-def send_account_deleted(to: str, operator: str | None) -> bool:
+def send_account_deleted(to: str, lang: str, operator: str | None) -> bool:
+    contact = mailtext.text("contact.deleted", lang, operator=operator) if operator else ""
+    body = mailtext.text("account_deleted.body", lang, contact=contact)
+    return _send([to], mailtext.text("account_deleted.subject", lang), body, reply_to=operator)
+
+
+def send_account_suspended(to: str, lang: str, operator: str | None) -> bool:
     contact = (
-        f"\n\nIf you didn't request this, contact the Siftlode operator at {operator}."
+        mailtext.text("contact.suspended", lang, operator=operator)
         if operator
-        else ""
+        else mailtext.text("contact.suspended_unknown", lang)
     )
-    body = (
-        "Hi,\n\n"
-        "Your Siftlode account and all associated data — subscriptions, tags, watch history, "
-        "playlists and settings — have been permanently deleted. Nothing is retained.\n\n"
-        "Thanks for having used Siftlode." + contact + "\n\n— Siftlode"
+    body = mailtext.text("account_suspended.body", lang, contact=contact)
+    return _send([to], mailtext.text("account_suspended.subject", lang), body, reply_to=operator)
+
+
+def send_admin_new_request(admins: list[str], lang: str, requester: str) -> bool:
+    """Tell the admins someone is waiting. One call per language group (see
+    `routes.auth.notify_admins_of_request`) — admins are people with their own UI language, and a
+    single blast to all of them would have to pick one and be wrong for the rest.
+
+    The link deep-links straight to the admin Access-requests page (the SPA reads ?admin=…). The
+    requester address is spelled out (mail clients auto-link both the URL and the address), and the
+    reply note is accurate: _send sets Reply-To to the requester, so a reply reaches THEM — not the
+    sending mailbox. (The old copy said "Settings → Account", which was the wrong menu.)
+    """
+    body = mailtext.text(
+        "admin_new_request.body",
+        lang,
+        requester=requester,
+        link=f"{settings.app_base}/?admin=access-requests",
     )
-    return _send([to], "Your Siftlode account has been deleted", body, reply_to=operator)
+    subject = mailtext.text("admin_new_request.subject", lang, requester=requester)
+    return _send(admins, subject, body, reply_to=requester)
 
 
-def send_account_suspended(to: str, operator: str | None) -> bool:
-    contact = (
-        f"If you think this is a mistake or have questions, contact the Siftlode operator "
-        f"at {operator}.\n\n"
-        if operator
-        else "If you think this is a mistake, please contact the Siftlode operator.\n\n"
+def send_verify_email(to: str, lang: str, link: str, hours: int = 24) -> bool:
+    # The body says what the link's rules are. The reset mail always has; this one left the reader to
+    # discover both by meeting a dead link, which is precisely the silence this epic removes.
+    body = mailtext.text(
+        "verify_email.body", lang, link=link, expiry=mailtext.link_expiry(hours, lang)
     )
-    body = (
-        "Hi,\n\n"
-        "A sign-in to your Siftlode account was just attempted, but the account is currently "
-        "suspended, so access was denied.\n\n" + contact + "— Siftlode"
-    )
-    return _send([to], "Your Siftlode account is suspended", body, reply_to=operator)
+    return _send([to], mailtext.text("verify_email.subject", lang), body)
 
 
-def send_admin_new_request(admins: list[str], requester: str) -> bool:
-    # The link deep-links straight to the admin Access-requests page (the SPA reads ?admin=…). The
-    # requester address is spelled out (mail clients auto-link both the URL and the address), and the
-    # reply note is accurate: _send sets Reply-To to the requester, so a reply reaches THEM — not the
-    # sending mailbox. (The old copy said "Settings → Account", which was the wrong menu.)
-    approve_url = f"{settings.app_base}/?admin=access-requests"
-    body = (
-        f"{requester} just requested access to Siftlode.\n\n"
-        f"Approve or deny it here:\n{approve_url}\n"
-        f"(or in Siftlode: open Users → Access requests)\n\n"
-        f"Requester's email: {requester}\n"
-        f"Replying to this message goes straight to the requester (it's the Reply-To address).\n"
-    )
-    return _send(admins, f"Siftlode access request from {requester}", body, reply_to=requester)
+def send_password_reset(to: str, lang: str, link: str) -> bool:
+    body = mailtext.text("password_reset.body", lang, link=link)
+    return _send([to], mailtext.text("password_reset.subject", lang), body)
 
 
-def send_verify_email(to: str, link: str) -> bool:
-    body = (
-        "Hi,\n\n"
-        "Confirm your email to finish creating your Siftlode account:\n\n"
-        f"{link}\n\n"
-        "If you didn't sign up, you can ignore this message.\n\n"
-        "— Siftlode"
-    )
-    return _send([to], "Confirm your Siftlode email", body)
-
-
-def send_password_reset(to: str, link: str) -> bool:
-    body = (
-        "Hi,\n\n"
-        "Use this link to set a new Siftlode password (it expires in an hour):\n\n"
-        f"{link}\n\n"
-        "If you didn't request this, you can ignore this message — your password is unchanged.\n\n"
-        "— Siftlode"
-    )
-    return _send([to], "Reset your Siftlode password", body)
-
-
-def send_test(to: str) -> bool:
-    body = (
-        "This is a test email from Siftlode.\n\n"
-        "If you're reading this, your SMTP settings work.\n\n"
-        "— Siftlode"
-    )
-    return _send([to], "Siftlode SMTP test", body)
+def send_test(to: str, lang: str) -> bool:
+    return _send([to], mailtext.text("test.subject", lang), mailtext.text("test.body", lang))

backend/app/feedquery.py

@@ -100,6 +100,11 @@ def serialize(row) -> dict:
     }
 
 
+def _tag_visible(user: User):
+    """A ChannelTag row this user may see: a shared system tag (user_id NULL) or their own."""
+    return or_(ChannelTag.user_id.is_(None), ChannelTag.user_id == user.id)
+
+
 def tags_by_category(db: Session, tag_ids: list[int]) -> dict[str, list[int]]:
     """Group tag ids by their category (language/topic/other). The single source for the category split
     shared by the feed's tag WHERE (filtered_query) and the facet/count summary (feed_summary), so the
@@ -118,6 +123,7 @@ def filtered_query(
     *,
     tags: list[int],
     tag_modes: dict[str, str],
+    untagged: bool = False,
     channel_ids: list[str],
     q: str | None,
     min_duration: int | None,
@@ -294,7 +300,7 @@ def filtered_query(
         # selections but still honours the other categories' filters).
         if exclude_tag_category:
             by_category.pop(exclude_tag_category, None)
-        visible = or_(ChannelTag.user_id.is_(None), ChannelTag.user_id == user.id)
+        visible = _tag_visible(user)
         for category, ids in by_category.items():
             if tag_modes.get(category, "or") == "and" and len(ids) > 1:
                 sub = (
@@ -307,6 +313,18 @@ def filtered_query(
                 sub = select(ChannelTag.channel_id).where(ChannelTag.tag_id.in_(ids), visible)
             query = query.where(Video.channel_id.in_(sub))
 
+    # "No tag" filter (item B): keep only channels the USER has not personally tagged in the channel
+    # manager — i.e. channels with no ChannelTag row owned by this user (user_id == me, source "user").
+    # System/auto tags (user_id NULL) don't count: this is "channels I haven't tagged yet". It's a plain
+    # channel-level narrowing (like channel_ids/date), NOT a tag-category selection, so feed_summary
+    # leaves it applied in the base pass and needs no mirror in passes().
+    if untagged:
+        query = query.where(
+            Video.channel_id.notin_(
+                select(ChannelTag.channel_id).where(ChannelTag.user_id == user.id)
+            )
+        )
+
     # Content type: Normal / Shorts / Live·Upcoming as a union of enabled types.
     # Explicit Watched/Saved/Hidden views show every type so nothing goes missing.
     explicit_view = show in ("watched", "hidden")
@@ -355,8 +373,9 @@ def feed_summary(db: Session, user: User, **params) -> dict:
     within, a category in "and" mode requires ALL its selected tags)."""
     tag_modes = params.get("tag_modes", {})
 
-    # ONE pass: per-channel video counts for the base filter, tags stripped so every candidate channel
-    # is present to facet over.
+    # ONE pass: per-channel video counts for the base filter, the positive tag filter stripped so every
+    # candidate channel is present to facet over. The "No tag" (untagged) filter is a plain channel-level
+    # narrowing, so it STAYS applied here (not stripped) and the facets naturally drill down within it.
     base, _rank = filtered_query(db, user, **{**params, "tags": []})
     ch_col = base.with_only_columns(Video.channel_id).subquery()
     channel_counts: dict[str, int] = dict(
@@ -386,7 +405,8 @@ def feed_summary(db: Session, user: User, **params) -> dict:
 
     def passes(ch_tags: set[int], exclude_cat: str | None) -> bool:
         # The Python mirror of filtered_query's SQL tag block (AND across categories, OR within,
-        # topic-AND requires all selected) — keep in lockstep; see the ⚠️ note there.
+        # topic-AND requires all selected) — keep in lockstep; see the ⚠️ note there. (The "No tag"
+        # filter is applied in the base query above, so it needs no mirror here.)
         for cat, sel in selected_by_cat.items():
             if cat == exclude_cat:
                 continue
@@ -417,6 +437,30 @@ def feed_summary(db: Session, user: User, **params) -> dict:
     return {"count": count, "facets": facets}
 
 
+def feed_years(db: Session, user: User, **params) -> list[dict]:
+    """Per-year video counts for the current filter context (item 8 / E8·S2): powers the year control's
+    quick chips + the "more…" per-year-counts dialog. Every OTHER filter (tags, channels, content type,
+    search, watch state, scope) still applies, but the publish-date narrowing itself is DROPPED —
+    published_after/before and max_age_days — so the year list is the full set of years available and
+    switching years stays a live drill-down (the same principle as the tag facets dropping their own
+    category). One grouped query, newest year first."""
+    base, _rank = filtered_query(
+        db,
+        user,
+        **{**params, "published_after": None, "published_before": None, "max_age_days": None},
+    )
+    pub = base.with_only_columns(Video.published_at.label("pub")).subquery()
+    # Bucket by UTC year to stay in lockstep with the year filter's boundaries (published_after/before
+    # are pinned to UTC in filtered_query). published_at is timestamptz, so a bare extract('year', …)
+    # would use the DB session timezone and, on a non-UTC session, bucket a video near a year boundary
+    # into a different year than the filter includes — the count and the drill-down feed would disagree.
+    year = func.extract("year", func.timezone("UTC", pub.c.pub))
+    rows = db.execute(
+        select(year.label("y"), func.count()).group_by(year).order_by(year.desc())
+    ).all()
+    return [{"year": int(y), "count": n} for y, n in rows if y is not None]
+
+
 # --- Keyset (cursor) pagination ---------------------------------------------
 #
 # Each sort is described as an ordered list of key columns (expression + direction

backend/app/mailtext.py

@@ -0,0 +1,373 @@
+"""Bilingual text for every outbound mail, and the one resolver that decides which language a
+recipient gets (E9.5 S7).
+
+Why a catalog instead of literals in `email.py`: HU/EN parity is a house rule for every user-facing
+string, and a mail is the one user-facing surface the reader CANNOT re-render by switching the UI
+language — it arrives once, in whatever language we picked, and stays that way. `test_mail_language.py`
+enforces that every key carries both languages *and* the same `{placeholders}`, so a half-translated
+mail fails the gate instead of reaching a person.
+
+The language is resolved by the REQUEST handler and handed to `send_*` as a plain code. It is never
+resolved inside the mail: every send runs as a `BackgroundTasks` job, after the request's session is
+gone — the same reason `_welcome_mail_parts` computes its link in the handler and not in the task.
+"""
+
+from sqlalchemy import select
+from sqlalchemy.orm import Session
+
+from app.models import Invite, User
+from app.utils import canonical_email
+
+SUPPORTED: tuple[str, ...] = ("en", "hu")
+DEFAULT = "en"
+
+
+def normalize(lang: str | None) -> str:
+    """Coerce anything to a language we can actually render. Storage is not a guarantee: a
+    `preferences.language` written by an older build (or a locale we no longer ship) must degrade to
+    English rather than raise inside a background task nobody is watching."""
+    return lang if lang in SUPPORTED else DEFAULT
+
+
+def text(key: str, lang: str | None, **values: object) -> str:
+    """Render one catalog entry. Unknown languages fall back to English (see `normalize`); an
+    unknown KEY raises, because that is a programming error the tests must surface, not something to
+    paper over with an empty line in someone's inbox."""
+    return MAIL_TEXT[key][normalize(lang)].format(**values)
+
+
+def link_expiry(hours: int, lang: str) -> str:
+    """How long a link lasts, in a unit a reader converts on sight. A whole number of days is
+    said in days — the approval mail's token lives seven of them, and "168 hours" is not an answer
+    to "how long have I got". A single day stays "24 hours", which is how everyone writes it."""
+    if hours >= 48 and hours % 24 == 0:
+        return text("duration.days", lang, n=hours // 24)
+    return text("duration.hours", lang, n=hours)
+
+
+def lang_for_user(user: User | None) -> str:
+    """The language a signed-up recipient gets: the one they picked in the app."""
+    prefs = (user.preferences or {}) if user is not None else {}
+    return normalize(prefs.get("language"))
+
+
+def lang_for_email(db: Session, email: str) -> str:
+    """The language for an address that may not have an account yet: their own account preference,
+    else the language they filled our access-request form in, else English.
+
+    Matched CANONICALLY like every other identity lookup in this epic, and it walks past rows that
+    carry no usable code instead of stopping at the first one — prod really does hold two accounts
+    for a single mailbox, and only one of them may have ever picked a language.
+    """
+    canon = canonical_email(email)
+    for prefs in (
+        db.execute(select(User.preferences).where(User.email_canonical == canon).order_by(User.id))
+        .scalars()
+        .all()
+    ):
+        code = (prefs or {}).get("language")
+        if code in SUPPORTED:
+            return code
+    for code in (
+        db.execute(select(Invite.lang).where(Invite.email_canonical == canon).order_by(Invite.id))
+        .scalars()
+        .all()
+    ):
+        if code in SUPPORTED:
+            return code
+    return DEFAULT
+
+
+# The brand line ("— Siftlode") and the product name are deliberately NOT catalog entries: they are
+# a name, not a translated string, and giving them keys would invite someone to "translate" them.
+MAIL_TEXT: dict[str, dict[str, str]] = {
+    # ── How long a link lasts ───────────────────────────────────────────────────────────────
+    # Rendered, not interpolated as a raw hour count: the approval mail's token lives seven days
+    # (E9.5 S6), and "expires in 168 hours" is a unit no reader converts.
+    "duration.hours": {"en": "{n} hours", "hu": "{n} óra"},
+    "duration.days": {"en": "{n} days", "hu": "{n} nap"},
+    # ── Shared closing fragments ────────────────────────────────────────────────────────────────
+    "contact.reply": {
+        "en": "\n\nQuestions? Just reply to this email ({admin}).",
+        "hu": "\n\nKérdésed van? Csak válaszolj erre a levélre ({admin}).",
+    },
+    "contact.operator": {
+        "en": "\n\nQuestions? Contact the operator at {operator}.",
+        "hu": "\n\nKérdésed van? Írj az üzemeltetőnek: {operator}.",
+    },
+    "contact.deleted": {
+        "en": "\n\nIf you didn't request this, contact the Siftlode operator at {operator}.",
+        "hu": "\n\nHa nem te kérted, írj a Siftlode üzemeltetőjének: {operator}.",
+    },
+    "contact.suspended": {
+        "en": (
+            "If you think this is a mistake or have questions, contact the Siftlode operator "
+            "at {operator}.\n\n"
+        ),
+        "hu": (
+            "Ha szerinted ez tévedés, vagy kérdésed van, írj a Siftlode üzemeltetőjének: "
+            "{operator}.\n\n"
+        ),
+    },
+    "contact.suspended_unknown": {
+        "en": "If you think this is a mistake, please contact the Siftlode operator.\n\n",
+        "hu": "Ha szerinted ez tévedés, keresd a Siftlode üzemeltetőjét.\n\n",
+    },
+    # ── The one paragraph that carries the whole onboarding flow (see email._next_step) ──────────
+    "next_step.verify": {
+        "en": (
+            "You already started an account, so there is just one step left. Confirm your email "
+            "address and you're in:\n\n"
+            "{link}\n\n"
+            "The link works once and expires in {expiry}. If it does, you can ask for a fresh "
+            "one from the sign-in page."
+        ),
+        "hu": (
+            "A fiókodat már elkezdted, úgyhogy egyetlen lépés maradt. Erősítsd meg az "
+            "e-mail-címed, és bent is vagy:\n\n"
+            "{link}\n\n"
+            "A link egyszer használható, és {expiry} múlva lejár. Ha lejárt, a belépési oldalon "
+            "kérhetsz újat."
+        ),
+    },
+    "next_step.sign_in": {
+        "en": "Your account is ready — just sign in:\n\n{app}",
+        "hu": "A fiókod készen áll — csak lépj be:\n\n{app}",
+    },
+    "next_step.register": {
+        "en": (
+            "Create your account whenever you feel like it:\n\n"
+            "{app}\n\n"
+            "We'll send you a confirmation link to finish, and then you're in."
+        ),
+        "hu": (
+            "Hozd létre a fiókod, amikor kedved tartja:\n\n"
+            "{app}\n\n"
+            "Küldünk egy megerősítő linket a befejezéshez, és már bent is vagy."
+        ),
+    },
+    # ── Access decision ─────────────────────────────────────────────────────────────────────────
+    "access_approved.subject": {
+        "en": "You're in — your Siftlode access is approved",
+        "hu": "Bent vagy — jóváhagytuk a Siftlode-hozzáférésed",
+    },
+    "access_approved.body": {
+        "en": (
+            "Hi,\n\n"
+            "Your request to use Siftlode has been approved — welcome aboard.\n\n"
+            "{next_step}\n\n"
+            "If you weren't expecting this, you can ignore the message.\n\n"
+            "— Siftlode{contact}"
+        ),
+        "hu": (
+            "Szia,\n\n"
+            "Jóváhagytuk a Siftlode-hozzáférési kérelmed — üdv a fedélzeten.\n\n"
+            "{next_step}\n\n"
+            "Ha nem számítottál erre, nyugodtan hagyd figyelmen kívül ezt a levelet.\n\n"
+            "— Siftlode{contact}"
+        ),
+    },
+    "access_invitation.subject": {
+        "en": "You're invited to Siftlode",
+        "hu": "Meghívtak a Siftlode-ra",
+    },
+    "access_invitation.body": {
+        "en": (
+            "Hi,\n\n"
+            "Someone has opened up Siftlode for you — a quiet, self-hosted reader for your YouTube "
+            "subscriptions. Every upload from the channels you follow lands in one feed you can "
+            "actually filter and sort, with no algorithm deciding what you see, and no Shorts or "
+            "livestreams unless you want them.\n\n"
+            "{next_step}\n\n"
+            "No rush — the door stays open.\n\n"
+            "— Siftlode{contact}"
+        ),
+        "hu": (
+            "Szia,\n\n"
+            "Valaki megnyitotta előtted a Siftlode-ot — ez egy csendes, saját üzemeltetésű olvasó "
+            "a YouTube-feliratkozásaidhoz. A követett csatornák minden feltöltése egyetlen "
+            "hírfolyamba érkezik, amit tényleg tudsz szűrni és rendezni; nincs algoritmus, ami "
+            "eldönti, mit látsz, és nincs Shorts vagy élő adás, hacsak nem kéred.\n\n"
+            "{next_step}\n\n"
+            "Nem sürget semmi — az ajtó nyitva marad.\n\n"
+            "— Siftlode{contact}"
+        ),
+    },
+    "access_denied.subject": {
+        "en": "About your Siftlode access request",
+        "hu": "A Siftlode-hozzáférési kérelmedről",
+    },
+    "access_denied.body": {
+        "en": (
+            "Hi,\n\n"
+            "Thanks for your interest in Siftlode. After review, your access request wasn't "
+            "approved this time.\n\n"
+            "If you think this was a mistake, you're welcome to reply and let us know.\n\n"
+            "— Siftlode{contact}"
+        ),
+        "hu": (
+            "Szia,\n\n"
+            "Köszönjük az érdeklődésed a Siftlode iránt. Átnéztük a kérelmed, de most nem hagytuk "
+            "jóvá.\n\n"
+            "Ha szerinted ez tévedés, válaszolj nyugodtan erre a levélre.\n\n"
+            "— Siftlode{contact}"
+        ),
+    },
+    # ── Account lifecycle ───────────────────────────────────────────────────────────────────────
+    "role_changed.subject": {
+        "en": "Your Siftlode role has changed",
+        "hu": "Megváltozott a szereped a Siftlode-on",
+    },
+    "role_changed.granted": {
+        "en": (
+            "You've been granted admin access on Siftlode — you can now manage settings, the "
+            "scheduler and users."
+        ),
+        "hu": (
+            "Admin jogot kaptál a Siftlode-on — mostantól kezelheted a beállításokat, az ütemezőt "
+            "és a felhasználókat."
+        ),
+    },
+    "role_changed.revoked": {
+        "en": "Your admin access on Siftlode has been removed — you're now a regular user.",
+        "hu": "Elvettük az admin jogod a Siftlode-on — mostantól sima felhasználó vagy.",
+    },
+    "role_changed.body": {
+        "en": "Hi,\n\n{line}{contact}\n\n— Siftlode",
+        "hu": "Szia,\n\n{line}{contact}\n\n— Siftlode",
+    },
+    "account_unsuspended.subject": {
+        "en": "Your Siftlode account has been reinstated",
+        "hu": "Visszaállítottuk a Siftlode-fiókod",
+    },
+    "account_unsuspended.body": {
+        "en": (
+            "Hi,\n\n"
+            "Your Siftlode account has been reinstated — the suspension was lifted and you can "
+            "sign in again.{contact}\n\n— Siftlode"
+        ),
+        "hu": (
+            "Szia,\n\n"
+            "Visszaállítottuk a Siftlode-fiókod — a felfüggesztést feloldottuk, újra be tudsz "
+            "lépni.{contact}\n\n— Siftlode"
+        ),
+    },
+    "account_deleted.subject": {
+        "en": "Your Siftlode account has been deleted",
+        "hu": "Töröltük a Siftlode-fiókod",
+    },
+    "account_deleted.body": {
+        "en": (
+            "Hi,\n\n"
+            "Your Siftlode account and all associated data — subscriptions, tags, watch history, "
+            "playlists and settings — have been permanently deleted. Nothing is retained.\n\n"
+            "Thanks for having used Siftlode.{contact}\n\n— Siftlode"
+        ),
+        "hu": (
+            "Szia,\n\n"
+            "A Siftlode-fiókod és minden hozzá tartozó adat — feliratkozások, címkék, megtekintési "
+            "előzmények, lejátszási listák és beállítások — véglegesen törölve. Semmit nem őrzünk "
+            "meg.\n\n"
+            "Köszönjük, hogy használtad a Siftlode-ot.{contact}\n\n— Siftlode"
+        ),
+    },
+    "account_suspended.subject": {
+        "en": "Your Siftlode account is suspended",
+        "hu": "A Siftlode-fiókod fel van függesztve",
+    },
+    "account_suspended.body": {
+        "en": (
+            "Hi,\n\n"
+            "A sign-in to your Siftlode account was just attempted, but the account is currently "
+            "suspended, so access was denied.\n\n{contact}— Siftlode"
+        ),
+        "hu": (
+            "Szia,\n\n"
+            "Valaki most próbált belépni a Siftlode-fiókodba, de a fiók jelenleg fel van "
+            "függesztve, ezért a belépést elutasítottuk.\n\n{contact}— Siftlode"
+        ),
+    },
+    # ── To the admins ───────────────────────────────────────────────────────────────────────────
+    "admin_new_request.subject": {
+        "en": "Siftlode access request from {requester}",
+        "hu": "Siftlode hozzáférési kérelem: {requester}",
+    },
+    "admin_new_request.body": {
+        "en": (
+            "{requester} just requested access to Siftlode.\n\n"
+            "Approve or deny it here:\n{link}\n"
+            "(or in Siftlode: open Users → Access requests)\n\n"
+            "Requester's email: {requester}\n"
+            "Replying to this message goes straight to the requester (it's the Reply-To address).\n"
+        ),
+        "hu": (
+            "{requester} most kért hozzáférést a Siftlode-hoz.\n\n"
+            "Itt hagyhatod jóvá vagy utasíthatod el:\n{link}\n"
+            "(vagy a Siftlode-ban: Felhasználók → Hozzáférési kérések)\n\n"
+            "A kérelmező e-mail-címe: {requester}\n"
+            "Ha erre a levélre válaszolsz, az egyenesen a kérelmezőhöz megy (ő a Reply-To cím).\n"
+        ),
+    },
+    # ── Link mails ──────────────────────────────────────────────────────────────────────────────
+    "verify_email.subject": {
+        "en": "Confirm your Siftlode email",
+        "hu": "Erősítsd meg a Siftlode e-mail-címed",
+    },
+    "verify_email.body": {
+        "en": (
+            "Hi,\n\n"
+            "Confirm your email to finish creating your Siftlode account:\n\n"
+            "{link}\n\n"
+            "The link works once and expires in {expiry}. If it does, you can ask for a fresh "
+            "one from the sign-in page.\n\n"
+            "If you didn't sign up, you can ignore this message.\n\n"
+            "— Siftlode"
+        ),
+        "hu": (
+            "Szia,\n\n"
+            "Erősítsd meg az e-mail-címed, hogy elkészüljön a Siftlode-fiókod:\n\n"
+            "{link}\n\n"
+            "A link egyszer használható, és {expiry} múlva lejár. Ha lejárt, a belépési oldalon "
+            "kérhetsz újat.\n\n"
+            "Ha nem te regisztráltál, nyugodtan hagyd figyelmen kívül ezt a levelet.\n\n"
+            "— Siftlode"
+        ),
+    },
+    "password_reset.subject": {
+        "en": "Reset your Siftlode password",
+        "hu": "Állíts be új Siftlode-jelszót",
+    },
+    "password_reset.body": {
+        "en": (
+            "Hi,\n\n"
+            "Use this link to set a new Siftlode password (it expires in an hour):\n\n"
+            "{link}\n\n"
+            "If you didn't request this, you can ignore this message — your password is "
+            "unchanged.\n\n"
+            "— Siftlode"
+        ),
+        "hu": (
+            "Szia,\n\n"
+            "Ezzel a linkkel állíthatsz be új Siftlode-jelszót (egy óra múlva lejár):\n\n"
+            "{link}\n\n"
+            "Ha nem te kérted, hagyd figyelmen kívül ezt a levelet — a jelszavad változatlan.\n\n"
+            "— Siftlode"
+        ),
+    },
+    "test.subject": {
+        "en": "Siftlode SMTP test",
+        "hu": "Siftlode SMTP-teszt",
+    },
+    "test.body": {
+        "en": (
+            "This is a test email from Siftlode.\n\n"
+            "If you're reading this, your SMTP settings work.\n\n"
+            "— Siftlode"
+        ),
+        "hu": (
+            "Ez egy teszt e-mail a Siftlode-tól.\n\n"
+            "Ha ezt olvasod, az SMTP-beállításaid működnek.\n\n"
+            "— Siftlode"
+        ),
+    },
+}

backend/app/models.py

@@ -17,9 +17,10 @@ from sqlalchemy import (
     func,
 )
 from sqlalchemy.dialects.postgresql import JSONB, TSVECTOR
-from sqlalchemy.orm import Mapped, mapped_column, relationship
+from sqlalchemy.orm import Mapped, mapped_column, relationship, validates
 
 from app.db import Base
+from app.utils import canonical_email
 
 
 class TimestampMixin:
@@ -29,6 +30,21 @@ class TimestampMixin:
     created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
 
 
+class CanonicalEmailMixin:
+    """Keeps `email_canonical` derived from `email` on every write.
+
+    The invariant — "identity is matched on the canonical form, mail is sent to the typed one" —
+    lives HERE, in code, instead of in a comment every write site has to remember. That distinction
+    is what the 2026-09-03 lockout was made of: one gate lowercased, nothing else did, and an
+    approved user's Google sign-in silently became a second access request.
+    """
+
+    @validates("email")
+    def _derive_email_canonical(self, _key: str, value: str | None) -> str | None:
+        self.email_canonical = canonical_email(value)
+        return value
+
+
 class UpdatedAtMixin:
     """Adds an `updated_at` that server-defaults on insert and bumps on every UPDATE."""
 
@@ -37,7 +53,7 @@ class UpdatedAtMixin:
     )
 
 
-class User(Base, TimestampMixin):
+class User(Base, TimestampMixin, CanonicalEmailMixin):
     __tablename__ = "users"
 
     id: Mapped[int] = mapped_column(primary_key=True)
@@ -45,8 +61,26 @@ class User(Base, TimestampMixin):
     # multiple NULLs under a unique index). Set on Google sign-in / in-app linking.
     google_sub: Mapped[str | None] = mapped_column(String(64), unique=True, index=True)
     email: Mapped[str] = mapped_column(String(320), unique=True, index=True)
+    # The same mailbox, in the form used to MATCH identities (utils.canonical_email) — Gmail dots and
+    # `+tags` folded away. Kept by the validator below so no write site can forget it. Deliberately
+    # NOT unique: prod already carries two rows for one mailbox (a password registration and the
+    # Google sign-in that failed to find it), and a migration must not merge accounts on its own.
+    email_canonical: Mapped[str] = mapped_column(String(320), index=True, server_default="")
+    # The address Google asserted for this account, recorded at sign-in / link time. NOT the same
+    # thing as `email`: since E9.5 S3 a Google sign-in no longer overwrites the address the user
+    # registered with, so a deliberate `me+siftlode@gmail.com` survives — and this is where the other
+    # half of the truth lives, for the UI to show when the two differ. NULL until the next Google
+    # sign-in for accounts linked before this column existed.
+    google_email: Mapped[str | None] = mapped_column(String(320))
     # argon2id hash for email+password login; NULL for Google-only / demo accounts.
     password_hash: Mapped[str | None] = mapped_column(String(255))
+    # When SEC-10 dropped a preset password on Google adoption (see the single caller of
+    # auth.revoke_preset_password_if_unverified; admin approval no longer revokes — E9.5 S1). Without
+    # this trace a revoked account was indistinguishable from a Google-only one, so it failed the
+    # password-reset eligibility check and could never be recovered — it could neither sign in nor
+    # reset. Set = "had a password, lost it to the guard" -> reset-eligible. Cleared whenever a
+    # password is set again (reset-confirm / set-password).
+    password_revoked_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
     # Email ownership proven (Google sign-in is implicitly verified; password registration
     # verifies via a link). Login requires this AND is_active.
     email_verified: Mapped[bool] = mapped_column(Boolean, default=False, server_default="false")
@@ -114,7 +148,7 @@ class AuthToken(Base, TimestampMixin):
     used_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
 
 
-class Invite(Base):
+class Invite(Base, CanonicalEmailMixin):
     """Access-request / whitelist row. Source of truth for who may sign in; the env
     ALLOWED_EMAILS/ADMIN_EMAILS act only as a bootstrap fallback (see auth.is_allowed)."""
 
@@ -122,6 +156,9 @@ class Invite(Base):
 
     id: Mapped[int] = mapped_column(primary_key=True)
     email: Mapped[str] = mapped_column(String(320), unique=True, index=True)
+    # See User.email_canonical. Not unique here either: prod has approved invites for both spellings
+    # of the same mailbox, dating back to 2026-06-16.
+    email_canonical: Mapped[str] = mapped_column(String(320), index=True, server_default="")
     # pending | approved | denied
     status: Mapped[str] = mapped_column(String(16), default="pending", server_default="pending")
     note: Mapped[str | None] = mapped_column(Text)
@@ -130,6 +167,17 @@ class Invite(Base):
     )
     decided_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
     decided_by: Mapped[str | None] = mapped_column(String(320))  # admin email
+    # When the admin last SENT this person an invitation from the whitelist row. Adding an address
+    # stays silent — it opens a door, it does not knock — so telling them is a separate, deliberate
+    # act, and this is what stops it happening twice to a real person.
+    invited_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+    # The language this person asked us in ("en"/"hu"), captured when the request was made: the page
+    # their form was on, or the locale Google reported for a refused sign-in. NULL for a row the
+    # admin whitelisted by hand — nobody has told us anything about that mailbox, which is exactly
+    # why the invitation send asks (E9.5 S7). Captured rather than derived for the same reason
+    # `preferences.language` and `google_email` are: the signal exists only in that one moment and
+    # cannot be backfilled afterwards.
+    lang: Mapped[str | None] = mapped_column(String(8))
 
 
 class DemoWhitelist(Base, TimestampMixin):
@@ -551,6 +599,10 @@ class Playlist(Base, TimestampMixin, UpdatedAtMixin):
     # SHA-256 of name + ordered video ids as last synced from / pushed to YouTube; the
     # baseline `dirty` is derived against. NULL = no baseline yet (treated as dirty).
     synced_fingerprint: Mapped[str | None] = mapped_column(String)
+    # JSON list of the ordered video ids as of the last sync — the 3-way-merge baseline the
+    # two-way YouTube sync classifies each item against (local-add vs YT-add vs real delete).
+    # NULL = no baseline yet; the first merge then does a lossless union (never deletes).
+    synced_video_ids: Mapped[str | None] = mapped_column(Text)
     position: Mapped[int] = mapped_column(Integer, default=0, server_default="0")
 
     items: Mapped[list["PlaylistItem"]] = relationship(
@@ -704,6 +756,12 @@ class MediaAsset(Base, TimestampMixin):
     container: Mapped[str | None] = mapped_column(String(16))
     vcodec: Mapped[str | None] = mapped_column(String(32))
     acodec: Mapped[str | None] = mapped_column(String(32))
+    # "video" | "audio" | "file" — the media-kind discriminator that drives which library actions
+    # apply (play/edit for media; download-only for a generic uploaded file). Null while an asset is
+    # still pending (kind is known once the file is probed at finalize). It is the single stored home
+    # of the invariant `downloads.mediakind.derive` used to compute — never re-derived in prose (an
+    # earlier ad-hoc `vcodec is None and acodec` check lived only in links.py; consolidated here).
+    media_kind: Mapped[str | None] = mapped_column(String(16))
     nfo_written: Mapped[bool] = mapped_column(Boolean, default=False, server_default="false")
     # Set once the GC has warned holders of the upcoming expiry, so it doesn't warn every run.
     gc_notified: Mapped[bool] = mapped_column(Boolean, default=False, server_default="false")
@@ -867,6 +925,35 @@ class DownloadLink(Base, TimestampMixin):
     view_count: Mapped[int] = mapped_column(Integer, default=0, server_default="0")
 
 
+class DownloadCredential(Base, TimestampMixin, UpdatedAtMixin):
+    """A user's stored login cookies for ONE auth-walled download host (Facebook, Instagram, …).
+
+    Per-user, per-host: each user pastes their OWN browser cookies.txt (Netscape format) for a host
+    where they're logged in (e.g. a closed Facebook group they belong to), and a download of a
+    yt-dlp-supported, auth-walled link on that host is retried with the ACTING user's cookie. The
+    blob is Fernet-encrypted at rest (`cookies_enc`) and is NEVER returned by any API/log/audit —
+    the routes are write-only (host + updated_at only). See `downloads.credentials`.
+
+    Two load-bearing security controls live around this row, NOT on it:
+      * **cache privacy** — a cookie-authed download SALTS its MediaAsset `format_sig` with the
+        user id, so the authed asset is private to that user and can never be cache-served to
+        another user (`downloads.credentials.cookie_salt`).
+      * **host scope (SEC-12)** — a cookie is attached ONLY when the download URL's netloc matches
+        this row's `host_key` (`downloads.credentials.host_key_for_url`), so an arbitrary `?url=`
+        can't exfiltrate the user's session to a look-alike host.
+
+    `host_key` is a short canonical key from the supported-host registry (e.g. "facebook"), not the
+    raw netloc — one credential can cover several domains of the same site (facebook.com/fb.watch)."""
+
+    __tablename__ = "download_credentials"
+    __table_args__ = (UniqueConstraint("user_id", "host_key", name="uq_download_credential"),)
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    user_id: Mapped[int] = mapped_column(ForeignKey("users.id", ondelete="CASCADE"), index=True)
+    host_key: Mapped[str] = mapped_column(String(64))
+    cookies_enc: Mapped[str] = mapped_column(Text)  # Fernet ciphertext — never returned/logged
+
+
 class MessageKey(Base, TimestampMixin):
     """A user's end-to-end-encryption key material for direct messaging (phase 2).
 
@@ -1088,6 +1175,22 @@ class PlexItem(Base, TimestampMixin, UpdatedAtMixin):
     # Browser-playability class from ffprobe: "direct" | "remux" | "transcode" (None = unprobed).
     playable: Mapped[str | None] = mapped_column(String(12), index=True)
     probed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+    # Transcode HW-capability facet (E7 playback-class filter). NULL for non-transcode items; for a
+    # `playable="transcode"` item: True = the prod iGPU can hardware-transcode it (codec is HW-decodable
+    # AND the source is 8-bit SDR), False = software libx264 only (AV1/XviD, or a 10-bit/HDR source that
+    # breaks the VAAPI nv12 pipeline — see plex/stream.py). Derived by `plex.sync.transcode_hw_capable`:
+    # set codec-only at sync (bit depth unknown from the cheap listing), then refined by the bit-depth
+    # backfill (`_probe_media_batch`) which downgrades a 10-bit/HDR HEVC to False. The one filterable
+    # home of the invariant `_want_hw`'s source gate computes at play time — kept in sync via the shared
+    # classifier so the catalog facet and the runtime encoder choice never disagree by codec.
+    transcode_hw: Mapped[bool | None] = mapped_column(Boolean, index=True)
+    # Video bit depth (8/10/12…) from the Plex media Stream, filled by the bit-depth backfill. NULL =
+    # not yet probed. Surfaced on the info page (e.g. "HEVC · 10-bit") and feeds `transcode_hw`.
+    video_bit_depth: Mapped[int | None] = mapped_column(Integer)
+    # Watermark for the bit-depth backfill: when this item's media Stream was last probed for
+    # bit-depth/HDR. NULL = never (the backfill's work-list). Only HW-decodable transcode items are
+    # probed (the rest are SW-only by codec and need no bit-depth); see `_probe_media_batch`.
+    media_probed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
     # Intro/credit markers: [{"type": "intro"|"credits", "start_s": int, "end_s": int}, ...]
     markers: Mapped[list | None] = mapped_column(JSON)
     added_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), index=True)

backend/app/plex/cards.py

@@ -33,6 +33,7 @@ def movie_card(it: PlexItem, st: PlexState | None) -> dict:
         "thumb": f"/api/plex/image/{it.rating_key}",
         "art": _art_url(it.rating_key, it.art_key),
         "playable": it.playable,
+        "transcode_hw": it.transcode_hw,  # HW/SW transcode split → the 4-way corner-dot badge
         "status": st.status if st else "new",
         "position_seconds": st.position_seconds if st else 0,
     }
@@ -65,6 +66,7 @@ def episode_card(e: PlexItem, st: PlexState | None) -> dict:
         "duration_seconds": e.duration_s,
         "thumb": f"/api/plex/image/{e.rating_key}",
         "playable": e.playable,
+        "transcode_hw": e.transcode_hw,  # HW/SW transcode split → the 4-way corner-dot badge
         "status": st.status if st else "new",
         "position_seconds": st.position_seconds if st else 0,
     }

backend/app/plex/query.py

@@ -9,6 +9,8 @@ from datetime import datetime, timedelta, timezone
 from sqlalchemy import and_, case, func, or_, select, type_coerce
 from sqlalchemy.dialects.postgresql import JSONB
 
+from app.models import PlexItem
+
 TS_CONFIG = "public.unaccent_simple"
 
 # --- Language-aware column pickers (E5 S6) ----------------------------------
@@ -206,6 +208,33 @@ def apply_meta_filters(q, model, p: dict, lang: str = "en"):
     return q.where(*conds) if conds else q
 
 
+# --- Playback-class filter (E7) — MOVIE-ONLY (a show is an aggregate with no single class) ---------
+# The 4 classes the feed filter + facet expose, derived from the stored `playable` + `transcode_hw`.
+# ONE definition (this SQL CASE) so the filter WHERE and the facet counts can't drift: `playable_conds`
+# filters on it, `facets` groups by it. transcode_hw IS NOT True groups NULL (unprobed) with software.
+# Public — it is the shared source of truth imported by routes.plex.browse (facet order + zero-fill).
+PLAYBACK_CLASSES = ("direct", "remux", "transcode_hw", "transcode_sw")
+
+
+def playback_class_expr():
+    """SQL CASE mapping a PlexItem (movie) to its playback-class string, or NULL. The HW branch must
+    precede the generic transcode branch (ordered evaluation)."""
+    return case(
+        (PlexItem.playable == "direct", "direct"),
+        (PlexItem.playable == "remux", "remux"),
+        (and_(PlexItem.playable == "transcode", PlexItem.transcode_hw.is_(True)), "transcode_hw"),
+        (PlexItem.playable == "transcode", "transcode_sw"),
+        else_=None,
+    )
+
+
+def playable_conds(sel: list[str]) -> list:
+    """A one-element condition list (or empty) selecting the given playback classes — an OR via
+    `class IN (...)` over the shared CASE. Unknown keys are dropped."""
+    keep = [c for c in sel if c in PLAYBACK_CLASSES]
+    return [playback_class_expr().in_(keep)] if keep else []
+
+
 @dataclass
 class LibraryFilters:
     """The shared sidebar filter query-params for /library + /facets, declared once and injected via
@@ -228,6 +257,7 @@ class LibraryFilters:
     keywords: str | None = None  # TMDB keyword chips (E5 S5), CSV; language-neutral
     collections: str | None = None  # CSV of collection rating_keys
     collection_mode: str = "any"  # how multiple collections combine: any (OR, default) | all (AND)
+    playable: str | None = None  # CSV of playback classes: direct|remux|transcode_hw|transcode_sw
 
     def as_dict(self) -> dict:
         return {
@@ -247,6 +277,7 @@ class LibraryFilters:
             "keywords": self.keywords,
             "collections": self.collections,
             "collection_mode": self.collection_mode,
+            "playable": self.playable,
         }
 
 

backend/app/plex/rollup.py

@@ -43,8 +43,10 @@ def rollup(cards: list[dict]) -> dict:
 def agg_subquery(db: Session, user_id: int, include_resumed: bool = False):
     """Per-show episode counts for a user: total, watched, in-progress. Reused to (a) filter the show
     grid by aggregate watch-state, (b) compute each card's badge, and (c) drive the Discover
-    continue-watching rail. `include_resumed` adds `resumed_at` = max(progress_updated_at) across the
-    show's episodes, so the rail can order shows by how recently they were last progressed."""
+    continue-watching rail, and (d) the browse "last watched" sort. `include_resumed` adds `resumed_at`
+    = max(coalesce(progress_updated_at, watched_at)) across the show's episodes — i.e. how recently ANY
+    episode was last touched (resumed OR marked watched) — so callers can order shows by recency. A
+    fully-watched show (no resume progress) still gets a timestamp from its episodes' watched_at."""
     ps = aliased(PlexState)
     cols = [
         PlexItem.show_id.label("show_id"),
@@ -63,7 +65,9 @@ def agg_subquery(db: Session, user_id: int, include_resumed: bool = False):
         ).label("inprog"),
     ]
     if include_resumed:
-        cols.append(func.max(ps.progress_updated_at).label("resumed_at"))
+        cols.append(
+            func.max(func.coalesce(ps.progress_updated_at, ps.watched_at)).label("resumed_at")
+        )
     return (
         select(*cols)
         .outerjoin(ps, and_(ps.item_id == PlexItem.id, ps.user_id == user_id))

backend/app/plex/stream.py

@@ -3,7 +3,10 @@
 Playback is from the LOCAL physical file. Browser-compatible files (playable="direct") are served
 raw with HTTP range requests. Everything else that is h264 video (playable="remux") is remuxed on
 the fly to HLS with **video stream-copy** (cheap, I/O-bound — no video re-encode) and audio to AAC
-when needed. HEVC/VP9 (playable="transcode") needs a full re-encode and is deferred to P3.
+when needed. Non-h264 video (playable="transcode": HEVC/VP9/AV1/MPEG-2/XviD…) needs a full re-encode
+to H.264: on the prod host that runs on the Intel iGPU via VAAPI (`h264_vaapi`, near-zero CPU), with
+software libx264 as the automatic fallback where the render node is absent or the source codec isn't
+hardware-decodable. Same HLS session/seek machinery either way — only the video encoder differs.
 
 Seek model (Jellyfin-style): one ffmpeg session per item, started at a given offset via `-ss`
 (fast keyframe seek). A seek beyond the generated region restarts the session at the new offset,
@@ -16,6 +19,7 @@ CPU-only prod host; only P3's full transcode is CPU-heavy.
 """
 
 import logging
+import os
 import re
 import shutil
 import subprocess
@@ -27,8 +31,10 @@ from sqlalchemy.orm import Session as DbSession
 
 from app import sysconfig
 from app.config import settings
+from app.downloads.edit import encode_thread_cap
 from app.models import PlexItem
 from app.plex import paths
+from app.plex.sync import HW_DECODABLE_CODECS
 
 log = logging.getLogger("siftlode.plex")
 
@@ -38,6 +44,17 @@ _HLS_ROOT = (
     else Path(settings.download_root) / ".plex-hls"
 )
 _SEG_SECONDS = 6
+# Cold-start warm-up. A freshly-spawned ffmpeg has produced only the first segment (or two) by the
+# time we could report the session ready; hls.js parses the EVENT playlist, drains that tiny buffer,
+# then STALLS a few seconds into playback waiting for the next segment the still-warming ffmpeg
+# hasn't written yet. Very visible on auto-advance to the next episode (start_s==0, which previously
+# returned with ZERO buffer). So before reporting ready we wait for the first few segments to exist:
+# the client then starts with ~_WARMUP_SEGMENTS×_SEG_SECONDS of buffer and, since stream-copy runs
+# faster than realtime, ffmpeg stays ahead from there and never stalls again. Best-effort and bounded
+# — we stop at the first segment that isn't ready within the per-segment budget (a slow miss is no
+# worse than the old zero-buffer behaviour).
+_WARMUP_SEGMENTS = 3
+_WARMUP_SEG_TIMEOUT_S = 8.0
 _SESSION_IDLE_S = 600  # reap a session with no access for this long
 # A session directory is named `{rating_key}_{int(start_s)}_{tag}_{aoff:+.2f}` (see start_session);
 # before multi-audio it was just `{rating_key}_{int(start_s)}`. `sweep_orphans` deletes ONLY names
@@ -72,11 +89,22 @@ _sessions: dict[str, "HlsSession"] = {}
 
 class HlsSession:
     def __init__(
-        self, key: str, directory: Path, proc: subprocess.Popen, start_s: float, entry: str
+        self,
+        key: str,
+        directory: Path,
+        proc: subprocess.Popen,
+        start_s: float,
+        entry: str,
+        transcode: bool = False,
+        hw: bool = False,
+        tonemap: bool = False,
     ):
         self.key = key
         self.dir = directory
         self.proc = proc
+        self.transcode = transcode  # video re-encoded (non-h264 source), not stream-copied
+        self.hw = hw  # transcode ran on the VAAPI hardware encoder (else libx264 software)
+        self.tonemap = tonemap  # HW HDR/10-bit path: OpenCL tonemap between VAAPI decode and encode
         self.start_s = start_s  # the REQUESTED seek offset
         # The REAL media start: with `-ss X -c:v copy` ffmpeg can only cut at the nearest earlier
         # keyframe K<=X, and hls.js zero-bases the timeline to K (so video.currentTime=0 is K, not X).
@@ -116,6 +144,269 @@ _HLS_TAIL = [
 ]
 
 
+# --- Transcode (playable="transcode") video re-encode -----------------------------------------
+# The remux path stream-copies the video (`-c:v copy`); a non-h264 source can't be copied and must be
+# re-encoded to H.264. The encoder + tonemap are chosen per-session by `_select_encode`:
+#   * VAAPI hardware (`h264_vaapi`) — the prod default once the iGPU is passed in. A full GPU pipeline
+#     (decode + scale + encode all on-device) offloads the CPU almost entirely, so several concurrent
+#     1080p transcodes are fine and the API stays responsive.
+#   * libx264 software — the automatic fallback where `/dev/dri` is absent (dev box, or prod before the
+#     iGPU enablement) or the source codec isn't hardware-decodable (AV1/XviD on Gen 9.5). CPU-bound, so
+#     it reserves a core via `-threads` (see encode_thread_cap).
+# Everything else — the `-copyts`/`_HLS_TAIL`/segment/seek-restart model and the AAC audio path — is
+# unchanged, so hls.js, subtitles, multi-audio and seeking keep working exactly as for remux.
+_VAAPI_DEVICE = "/dev/dri/renderD128"
+# Where an OpenCL ICD registers its driver. The Intel NEO runtime (intel-opencl-icd) drops an .icd file
+# here; its presence is the precondition for the HW HDR→SDR tonemap graph (see _opencl_present).
+_OPENCL_ICD_DIR = Path("/etc/OpenCL/vendors")
+# Codecs the prod iGPU (UHD 630 / Quick Sync Gen 9.5) can hardware-DECODE — the precondition for the
+# full-GPU VAAPI pipeline. A source outside it (AV1, MPEG-4 ASP/XviD…) falls back to software even with
+# the render node present, because the GPU can't decode it to feed its own encoder. THE single source is
+# plex.sync, so the runtime encoder choice here and the catalog `transcode_hw` facet can't disagree by
+# codec; aliased to the old name to keep the call sites below unchanged.
+_HW_DECODABLE = HW_DECODABLE_CODECS
+# Color-transfer values that mark a true-HDR source (PQ / HLG). A HW-decodable HDR source can't take the
+# plain scale_vaapi=format=nv12 path (Gen 9.5 VPP refuses it) — it needs the OpenCL tonemap graph
+# (_venc_opts tonemap branch) when the OpenCL runtime is present, else software libx264. A 10-bit source
+# WITHOUT one of these transfers is SDR, not HDR, and must not be tone-mapped. See _probe_video_kind.
+_HDR_TRANSFERS = {"smpte2084", "arib-std-b67"}
+
+
+# The three source classes that drive the transcode-pipeline choice (see _probe_video_kind).
+_VK_HWSAFE = "hwsafe"  # 8-bit SDR — the plain scale_vaapi=format=nv12 GPU path
+_VK_HDR = "hdr"  # PQ/HLG HDR — needs the OpenCL tonemap graph (or software if no runtime)
+_VK_SDR10 = "sdr10"  # 10-bit *SDR* — a plain 10→8-bit downconvert, NEVER the HDR tone curve
+
+
+def _probe_video_kind(src: Path) -> str:
+    """Classify the source for the transcode pipeline — one of `_VK_HWSAFE` / `_VK_HDR` / `_VK_SDR10`:
+
+      * `_VK_HWSAFE` — 8-bit SDR: safe for the plain VAAPI path (`scale_vaapi=format=nv12` + h264_vaapi).
+      * `_VK_HDR`    — PQ/HLG HDR (any depth): the plain scale path breaks on Gen 9.5 VPP, so it needs the
+        OpenCL tonemap graph (`tonemap_opencl=hable`) when the runtime is present, else software libx264.
+      * `_VK_SDR10`  — 10-bit but *SDR* (bt709 etc.): NOT HDR. Applying the HDR hable tone curve here would
+        visibly alter an SDR picture (crushed highlights/midtones) where only a 10→8-bit downconvert was
+        needed, so it must NOT take the tonemap graph — it goes to software libx264, which CPU-decodes and
+        downconverts to 8-bit yuv420p exactly. (Kept off the plain scale_vaapi 10-bit path too: that path
+        is unverified on Gen 9.5 VPP, and software is the known-correct downconvert.)
+
+    Ground truth from ffprobe (bit depth via pix_fmt / bits_per_raw_sample, HDR via color_transfer); the
+    Plex mirror doesn't store these. Returns `_VK_HWSAFE` on any probe failure: the runtime HW→SW fallback
+    in start_session backstops a HW session that still produces nothing, so a probe miss only costs the
+    rare wasted first attempt, never a stranded item."""
+    try:
+        out = subprocess.run(
+            [
+                "ffprobe",
+                "-v",
+                "error",
+                "-select_streams",
+                "v:0",
+                "-show_entries",
+                "stream=pix_fmt,bits_per_raw_sample,color_transfer",
+                "-of",
+                "default=noprint_wrappers=1",
+                str(src),
+            ],
+            capture_output=True,
+            text=True,
+            timeout=10,
+        )
+    except (subprocess.SubprocessError, OSError):
+        return _VK_HWSAFE
+    pix_fmt = bits = transfer = ""
+    for line in out.stdout.splitlines():
+        k, _, v = line.strip().partition("=")
+        v = v.strip().lower()
+        if k == "pix_fmt":
+            pix_fmt = v
+        elif k == "bits_per_raw_sample":
+            bits = v
+        elif k == "color_transfer":
+            transfer = v
+    if transfer in _HDR_TRANSFERS:
+        return _VK_HDR  # PQ/HLG — needs a real HDR→SDR tonemap, not a plain downconvert
+    # >8-bit but not HDR = 10-bit SDR. bits_per_raw_sample OR the pix_fmt bit-depth suffix
+    # (yuv420p10le, p010le, yuv444p12le…) signals >8-bit even when the other is absent.
+    if (bits.isdigit() and int(bits) > 8) or re.search(r"(?:10|12|16)(?:le|be)$", pix_fmt):
+        return _VK_SDR10
+    return _VK_HWSAFE
+
+
+def _opencl_present() -> bool:
+    """Whether an OpenCL runtime (Intel NEO / intel-opencl-icd) is installed — the precondition for the
+    HW HDR→SDR tonemap graph. Gen 9.5 VPP can't tonemap natively (tonemap_vaapi fails), so the working
+    HW path for a 10-bit/HDR source is VAAPI-decode → OpenCL tonemap → VAAPI-encode, which needs an ICD
+    registered here. Absent on the dev box and until the image bakes NEO in → those sources take
+    software libx264. Its own function so it's monkeypatchable in tests, mirroring _render_node_present."""
+    try:
+        return any(_OPENCL_ICD_DIR.glob("*.icd"))
+    except OSError:
+        return False
+
+
+def _hwaccel_in_opts(hw: bool, tonemap: bool = False) -> list[str]:
+    """VAAPI decode options, placed before `-i` so the source is decoded (and kept) on the GPU.
+    `-hwaccel_output_format vaapi` keeps frames as GPU surfaces all the way to `h264_vaapi` — no
+    round-trip to system memory. Empty for the software path.
+
+    The tonemap variant additionally derives an OpenCL device FROM the VAAPI one (`opencl=ocl@va`) so
+    tonemap_opencl can map the decoded surfaces zero-copy (see _venc_opts); it needs named devices, so it
+    uses `-init_hw_device` + `-hwaccel_device` rather than the plain path's implicit `-vaapi_device`."""
+    if not hw:
+        return []
+    if tonemap:
+        return [
+            "-init_hw_device",
+            f"vaapi=va:{_VAAPI_DEVICE}",
+            "-init_hw_device",
+            "opencl=ocl@va",
+            "-hwaccel",
+            "vaapi",
+            "-hwaccel_output_format",
+            "vaapi",
+            "-hwaccel_device",
+            "va",
+        ]
+    return ["-hwaccel", "vaapi", "-hwaccel_output_format", "vaapi", "-vaapi_device", _VAAPI_DEVICE]
+
+
+def _venc_opts(
+    transcode: bool,
+    hw: bool,
+    tonemap: bool = False,
+    preset: str = "veryfast",
+    crf: int = 20,
+    max_height: int = 0,
+) -> list[str]:
+    """The video-encoder args that replace `-c:v copy` for a transcode session (returns the copy args
+    when not transcoding). A re-encode must MINT its own keyframes at the segment boundaries — the copy
+    path leaned on the source's keyframes, but a re-encoded stream has none the HLS muxer can cut on
+    unless we force them (`-force_key_frames` every `_SEG_SECONDS`), else segments aren't independent and
+    seeking breaks. `preset`/`crf`/`max_height` (software only) come from admin sysconfig."""
+    if not transcode:
+        return ["-c:v", "copy"]
+    force_kf = ["-force_key_frames", f"expr:gte(t,n_forced*{_SEG_SECONDS})"]
+    if hw and tonemap:
+        # HDR/10-bit HW path: Gen 9.5 VPP can't tonemap (scale_vaapi=format=nv12 fails), so the decoded
+        # VAAPI surfaces are mapped to OpenCL (hwmap=derive_device=opencl), tone-mapped HDR→SDR to 8-bit
+        # nv12 there (tonemap_opencl, hable curve, bt709 out), then mapped back to VAAPI (reverse=1) for
+        # h264_vaapi. `-filter_hw_device ocl` tells the filter graph which device to run the OpenCL
+        # filters on. Full GPU pipeline — ~1 CPU core, several×realtime on the UHD 630 (measured).
+        return [
+            "-filter_hw_device",
+            "ocl",
+            "-vf",
+            "hwmap=derive_device=opencl,"
+            "tonemap_opencl=tonemap=hable:transfer=bt709:matrix=bt709:primaries=bt709:format=nv12,"
+            "hwmap=derive_device=vaapi:reverse=1",
+            "-c:v",
+            "h264_vaapi",
+            *force_kf,
+        ]
+    if hw:
+        # scale_vaapi with format=nv12 downconverts a 10-bit (p010) HEVC source to 8-bit nv12 so
+        # h264_vaapi (8-bit High) can encode it; for an 8-bit source it's a cheap format pass-through.
+        # The GPU encode is cheap, so it runs at source resolution (max_height is a software-only knob).
+        return ["-vf", "scale_vaapi=format=nv12", "-c:v", "h264_vaapi", *force_kf]
+    # Software fallback: same browser-safe recipe as downloads/edit.py (libx264). yuv420p forces 8-bit
+    # High (not High10) so any browser decodes it; -threads reserves a core so the CPU-bound encode can't
+    # starve request handling / playback on the shared box.
+    args: list[str] = []
+    if max_height and max_height > 0:
+        # Downscale-ONLY to the height cap (min(ih,H)), keeping aspect with an even width (-2), so a tall
+        # source doesn't make the software re-encode ruinously expensive. The comma in min() is escaped
+        # (\,) so ffmpeg's filter parser reads one filter, not two. Never upscales a smaller source.
+        args += ["-vf", f"scale=-2:min(ih\\,{max_height})"]
+    args += [
+        "-c:v",
+        "libx264",
+        "-preset",
+        preset,
+        "-crf",
+        str(crf),
+        "-pix_fmt",
+        "yuv420p",
+        "-threads",
+        str(encode_thread_cap()),
+        *force_kf,
+    ]
+    return args
+
+
+def _render_node_present() -> bool:
+    """Whether the VAAPI render node is available — i.e. `/dev/dri` was passed into the container.
+    Present on prod after the iGPU enablement; absent on the CPU-only dev box and in the localdev
+    Docker. Its own function so the selection is monkeypatchable in tests and one place for S1c's knob."""
+    return Path(_VAAPI_DEVICE).exists()
+
+
+def _select_encode(db: DbSession, item: PlexItem, transcode: bool, src: Path) -> tuple[bool, bool]:
+    """Pick the transcode video pipeline for this session — returns `(hw, tonemap)`:
+      * `(False, False)` → software libx264 (the fallback: no render node, non-decodable source, or a
+        10-bit/HDR source with no OpenCL runtime to tonemap on the GPU).
+      * `(True, False)`  → full-GPU VAAPI (`scale_vaapi=format=nv12` + `h264_vaapi`) — an 8-bit SDR source.
+      * `(True, True)`   → VAAPI decode → OpenCL tonemap → VAAPI encode — a true-HDR (PQ/HLG) source, when
+        the OpenCL runtime is present (Gen 9.5 VPP can't tonemap natively).
+
+    A 10-bit *SDR* source is deliberately NOT a `(True, True)` case: it needs a plain 10→8-bit downconvert,
+    not the HDR tone curve (which would visibly darken/flatten an SDR picture), so it drops to software.
+
+    Honours the admin `plex_transcode_hw` policy: "off" → always software; "on" → HW wherever the render
+    node exists (trusting the admin, skipping the decodability gate — the runtime HW→SW fallback still
+    backstops a session that produces nothing — but still routing a true-HDR source through the tonemap
+    graph so it doesn't hit the scale_vaapi wall); "auto" (default) → HW only when the render node is
+    present AND the iGPU can hardware-decode the source, with tonemap chosen only for a true-HDR (PQ/HLG)
+    source that has an OpenCL runtime, while a 10-bit SDR source drops to software."""
+    if not transcode:
+        return (False, False)
+    mode = (sysconfig.get_str(db, "plex_transcode_hw") or "auto").lower()
+    if mode == "off" or not _render_node_present():
+        return (False, False)
+    if mode == "on":
+        # Trust the admin: HW wherever the render node exists, skipping the decodability gate (the runtime
+        # backstop catches a miss). Only a true-HDR (PQ/HLG) source needs the tonemap graph — a 10-bit SDR
+        # source takes the plain scale path here, NOT the HDR tone curve. Probe only when OpenCL exists
+        # (short-circuit), so "on" stays probe-free where tonemap can't apply anyway.
+        tonemap = _opencl_present() and _probe_video_kind(src) == _VK_HDR
+        return (True, tonemap)
+    # auto
+    if (item.codec_video or "").lower() not in _HW_DECODABLE:
+        return (False, False)
+    kind = _probe_video_kind(src)
+    if kind == _VK_HWSAFE:
+        return (True, False)  # 8-bit SDR → full-GPU scale path
+    if kind == _VK_HDR:
+        # PQ/HLG: HW OpenCL tonemap when the runtime is present, else software libx264.
+        return (True, True) if _opencl_present() else (False, False)
+    # _VK_SDR10 — 10-bit SDR: a plain 10→8-bit downconvert, done exactly on the CPU. Never the HDR tone
+    # curve (it would alter an SDR picture), and off the unverified scale_vaapi 10-bit path — software.
+    return (False, False)
+
+
+def _want_hw(db: DbSession, item: PlexItem, transcode: bool, src: Path) -> bool:
+    """The HW gate on its own (the `hw` half of `_select_encode`). A readability shim for the tests that
+    assert only whether a session runs on the GPU (production decides via `_select_encode` directly)."""
+    return _select_encode(db, item, transcode, src)[0]
+
+
+# CPU-nice increment for the SOFTWARE transcode child. The Plex ffmpeg is a Popen in the long-lived API
+# process (which must NOT itself be niced), so — unlike the download worker's _deprioritize (run once in
+# its own main()) — we lower priority per-child via preexec_fn in the fork. The GPU path needs none of
+# this. Reuses the download child's nice default so all co-located re-encoders share one handicap.
+_SW_TRANSCODE_NICE = settings.download_child_nice
+
+
+def _sw_child_preexec() -> None:
+    """Runs in the forked child (POSIX) before exec: renice this software-transcode ffmpeg down so it
+    can't starve the co-located API / Postgres / playback. Best-effort — a failed renice must not fail
+    playback."""
+    try:
+        os.nice(_SW_TRANSCODE_NICE)
+    except OSError:
+        pass
+
+
 def _probe_audio_langs(src: Path) -> list[str]:
     """One entry per audio stream (its language tag, or "" if untagged). len() = audio-track count.
     Used to build the multi-rendition var_stream_map. Empty on probe failure → single-audio path."""
@@ -149,8 +440,19 @@ def _ffmpeg_cmd(
     audio_ord: int | None,
     aoff: float = 0.0,
     audio_langs: list[str] | None = None,
+    transcode: bool = False,
+    hw: bool = False,
+    tonemap: bool = False,
+    preset: str = "veryfast",
+    crf: int = 20,
+    max_height: int = 0,
 ) -> list[str]:
-    args = ["ffmpeg", "-nostdin", "-loglevel", "error"]
+    # For a transcode session the video is re-encoded (VAAPI or libx264) instead of stream-copied; the
+    # hwaccel decode options go before -i, the encoder args replace `-c:v copy` below. Everything else is
+    # identical to remux. `tonemap` is the HDR/10-bit HW variant (OpenCL tonemap between VAAPI decode and
+    # encode) — it needs matching decode-side (named devices) and encode-side (the OpenCL filter graph) opts.
+    venc = _venc_opts(transcode, hw, tonemap, preset, crf, max_height)
+    args = ["ffmpeg", "-nostdin", "-loglevel", "error", *_hwaccel_in_opts(hw, tonemap)]
     # Keep ORIGINAL timestamps on the output so the first segment carries the true absolute PTS of the
     # keyframe ffmpeg actually seeked to. hls.js still zero-bases playback to that PTS; we read it back
     # (see _probe_first_pts) to learn the real content offset. Without -copyts the segment PTS is
@@ -171,7 +473,7 @@ def _ffmpeg_cmd(
         args += ["-map", "0:v:0"]
         for i in range(len(audio_langs)):
             args += ["-map", f"{ai}:a:{i}?"]
-        args += ["-sn", "-c:v", "copy", "-c:a", "aac", "-ac", "2", "-b:a", "192k"]
+        args += ["-sn", *venc, "-c:a", "aac", "-ac", "2", "-b:a", "192k"]
         var = ["v:0,agroup:aud"]
         for i, lang in enumerate(audio_langs):
             entry = f"a:{i},agroup:aud,name:a{i}"
@@ -192,7 +494,7 @@ def _ffmpeg_cmd(
     else:
         ao = audio_ord if audio_ord is not None else 0
         args += ["-map", "0:v:0", "-map", f"{ai}:a:{ao}?", "-sn"]
-        args += ["-c:v", "copy", "-c:a", "aac", "-ac", "2", "-b:a", "192k"]
+        args += [*venc, "-c:a", "aac", "-ac", "2", "-b:a", "192k"]
         args += _HLS_TAIL + [
             "-hls_segment_filename",
             str(out_dir / "seg_%d.ts"),
@@ -247,12 +549,14 @@ def _kill(s: HlsSession) -> None:
 
 
 def _enforce_cap(cap: int) -> None:
-    # Caller holds _lock. Drop the least-recently-accessed sessions over the cap.
-    if len(_sessions) <= cap:
+    # Caller holds _lock. Only TRANSCODE sessions count toward plex_max_transcodes — remux
+    # (stream-copy) and direct-serve are cheap and deliberately uncapped (see config.py:
+    # plex_max_transcodes, and the user-facing config hint). Drop the least-recently-accessed
+    # transcode sessions over the cap, leaving any concurrent remux streams untouched.
+    tx = [(key, s) for key, s in _sessions.items() if s.transcode]
+    if len(tx) <= cap:
         return
-    for key, s in sorted(_sessions.items(), key=lambda kv: kv[1].last_access)[
-        : len(_sessions) - cap
-    ]:
+    for key, s in sorted(tx, key=lambda kv: kv[1].last_access)[: len(tx) - cap]:
         _kill(s)
         _sessions.pop(key, None)
 
@@ -264,11 +568,14 @@ def start_session(
     audio_ord: int | None = None,
     aoff: float = 0.0,
     multi: bool = False,
+    transcode: bool = False,
 ) -> HlsSession | None:
-    """(Re)start the HLS remux for an item at the given offset. `multi` (item has >1 audio track) maps
-    every audio track as an HLS rendition so the client switches audio without a restart; otherwise a
-    single audio track (`audio_ord`) is muxed. Subtitles are separate WebVTT tracks (not muxed here).
-    Returns None if the local file can't be read."""
+    """(Re)start the HLS session for an item at the given offset. `transcode` (item is non-h264,
+    playable="transcode") re-encodes the video to H.264 (VAAPI or libx264) instead of stream-copying it;
+    otherwise the video is copied (remux). `multi` (item has >1 audio track) maps every audio track as an
+    HLS rendition so the client switches audio without a restart; otherwise a single audio track
+    (`audio_ord`) is muxed. Subtitles are separate WebVTT tracks (not muxed here). Returns None if the
+    local file can't be read."""
     src = paths.local_media_path(db, item.file_path)
     if src is None:
         return None
@@ -276,43 +583,125 @@ def start_session(
     start_s = max(0.0, float(start_s))
     audio_langs = _probe_audio_langs(src) if multi else []
     is_multi = len(audio_langs) > 1  # only worth a master playlist when there really are ≥2 tracks
-    with _lock:
-        old = _sessions.pop(key, None)
-        if old is not None:
-            _kill(old)
-        tag = "multi" if is_multi else str(audio_ord)
-        directory = _HLS_ROOT / f"{key}_{int(start_s)}_{tag}_{aoff:+.2f}"
-        shutil.rmtree(directory, ignore_errors=True)
-        directory.mkdir(parents=True, exist_ok=True)
-        proc = subprocess.Popen(
-            _ffmpeg_cmd(
-                src, start_s, directory, audio_ord, aoff, audio_langs if is_multi else None
-            ),
-            stdout=subprocess.DEVNULL,
-            stderr=subprocess.DEVNULL,
+    tag = "multi" if is_multi else str(audio_ord)
+    directory = _HLS_ROOT / f"{key}_{int(start_s)}_{tag}_{aoff:+.2f}"
+
+    def _seg(i: int) -> Path:
+        # multi-audio: the video rendition is variant v0 → seg_{i}_0.ts; single-audio → seg_{i}.ts
+        return directory / (f"seg_{i}_0.ts" if is_multi else f"seg_{i}.ts")
+
+    def _spawn(
+        hw: bool, tonemap: bool = False, *, replace_only: "HlsSession | None" = None
+    ) -> "HlsSession | None":
+        # `replace_only` makes the supersede identity-aware for the runtime fallback: the whole
+        # check-and-replace happens under ONE _lock, so a newer same-key session (a concurrent
+        # seek-restart) installed between the fallback's decision and here is never clobbered. When the
+        # registered session is no longer `replace_only`, we abort and return None (the caller yields to
+        # whoever is registered now). The INITIAL spawn passes replace_only=None and always supersedes —
+        # that is the seek-restart's intended last-writer-wins.
+        # Software-fallback encode tuning — read only on the SW transcode path (the VAAPI path and
+        # remux ignore preset/crf/max_height, and remux must not touch the DB for them).
+        preset, crf, max_height = "veryfast", 20, 0
+        if transcode and not hw:
+            preset = sysconfig.get_str(db, "plex_transcode_preset") or "veryfast"
+            crf = sysconfig.get_int(db, "plex_transcode_crf")
+            max_height = sysconfig.get_int(db, "plex_transcode_max_height")
+        # Nice the SOFTWARE transcode child (not the HW path, and not remux) so a CPU-bound re-encode
+        # can't starve the co-located API/playback. preexec_fn runs in the forked child (POSIX); on a
+        # platform without fork (the API always runs in a Linux container in prod) it's simply omitted.
+        preexec = _sw_child_preexec if (transcode and not hw and os.name == "posix") else None
+        with _lock:
+            if replace_only is not None and _sessions.get(key) is not replace_only:
+                return None  # superseded/culled while we waited out of lock — don't clobber the newer one
+            old = _sessions.pop(key, None)
+            if old is not None:
+                _kill(old)
+            shutil.rmtree(directory, ignore_errors=True)
+            directory.mkdir(parents=True, exist_ok=True)
+            proc = subprocess.Popen(
+                _ffmpeg_cmd(
+                    src,
+                    start_s,
+                    directory,
+                    audio_ord,
+                    aoff,
+                    audio_langs if is_multi else None,
+                    transcode=transcode,
+                    hw=hw,
+                    tonemap=tonemap,
+                    preset=preset,
+                    crf=crf,
+                    max_height=max_height,
+                ),
+                stdout=subprocess.DEVNULL,
+                stderr=subprocess.DEVNULL,
+                preexec_fn=preexec,
+            )
+            s = HlsSession(
+                key,
+                directory,
+                proc,
+                start_s,
+                "master.m3u8" if is_multi else "index.m3u8",
+                transcode=transcode,
+                hw=hw,
+                tonemap=tonemap,
+            )
+            _sessions[key] = s
+            # Admin-configurable concurrency cap (Configuration → Plex → Max concurrent transcodes);
+            # at least 1 so playback can't be capped to zero.
+            _enforce_cap(max(1, sysconfig.get_int(db, "plex_max_transcodes")))
+        return s
+
+    s = _spawn(*_select_encode(db, item, transcode, src))
+    # Wait for the first video segment outside the lock (this blocks on ffmpeg, and we must not hold up
+    # other sessions). Pass the proc so a HW session that dies at VAAPI init fails fast (not after 25s).
+    ready = wait_for(_seg(0), timeout=25.0, proc=s.proc)
+    if not ready and s.hw:
+        # We waited on _seg(0) OUTSIDE _lock, so `s.proc` dying is ambiguous: it may have failed on its
+        # own (VAProfile/init/tonemap refusal), OR a concurrent same-key _spawn (a rapid seek-restart) or
+        # _enforce_cap may have killed it to install/keep a newer session. Respawn on libx264 (no HW, no
+        # tonemap) so a genuinely-failed GPU session never strands playback — but pass `replace_only=s` so
+        # the respawn is a no-op if we've been superseded: the identity check and the pop+replace share
+        # ONE lock in _spawn, so we can never tear down the newer session. s.hw is now False, so the route
+        # honestly reports "CPU" and the player's Preparing-stream state stays correct.
+        log.warning(
+            "plex transcode: HW session produced no segments — falling back to software key=%s", key
         )
-        s = HlsSession(key, directory, proc, start_s, "master.m3u8" if is_multi else "index.m3u8")
-        _sessions[key] = s
-        # Admin-configurable concurrency cap (Configuration → Plex → Max concurrent transcodes);
-        # at least 1 so playback can't be capped to zero.
-        _enforce_cap(max(1, sysconfig.get_int(db, "plex_max_transcodes")))
-    # Learn the REAL start offset K from the first VIDEO segment (outside the lock — this blocks on
-    # ffmpeg producing it, and we must not hold up other sessions). The client reads `media_start_s`, so
-    # its absolute clock + subtitle shift key off the true keyframe, not the requested offset. On
-    # timeout/probe failure we keep the provisional requested offset (old behaviour, small drift).
-    if start_s > 0:
-        seg0 = directory / ("seg_0_0.ts" if is_multi else "seg_0.ts")  # multi: video variant = v0
-        if wait_for(seg0, timeout=25.0):
-            k = _probe_first_pts(seg0)
+        respawned = _spawn(False, False, replace_only=s)
+        if respawned is None:
+            # Superseded/culled mid-fallback — yield whoever is registered now (a newer seek-restart), or
+            # our own now-dead session if the key was cap-culled. Never None here: the POST /session route
+            # turns a None return into a "Media file not found on disk" 404 — dishonest for a file that
+            # exists. A (dead) session instead degrades to a retryable 404 ("No active playback session" /
+            # "Not available yet") the client re-requests.
+            return current_session(key) or s
+        s = respawned
+        ready = wait_for(_seg(0), timeout=25.0, proc=s.proc)
+    if ready:
+        # For a seek (start_s>0) learn the REAL start offset K from the first segment's absolute PTS,
+        # so the client's absolute clock + subtitle shift key off the true keyframe, not the requested
+        # offset. On probe failure we keep the provisional requested offset (old behaviour, small drift).
+        if start_s > 0:
+            k = _probe_first_pts(_seg(0))
             if k is not None and k >= 0:
                 s.media_start_s = k
+        # Warm up the buffer (see _WARMUP_SEGMENTS) so the client doesn't outrun the cold ffmpeg. Stop
+        # at the first segment that isn't ready in time — ffmpeg produces them faster than realtime once
+        # warm, so a miss means something slow and we proceed rather than block the request further.
+        for i in range(1, _WARMUP_SEGMENTS):
+            if not wait_for(_seg(i), timeout=_WARMUP_SEG_TIMEOUT_S, proc=s.proc):
+                break
     log.info(
-        "plex hls session start key=%s req=%.1f real=%.3f multi=%s audio=%s",
+        "plex hls session start key=%s req=%.1f real=%.3f multi=%s audio=%s transcode=%s hw=%s tonemap=%s",
         key,
         start_s,
         s.media_start_s,
         is_multi,
         audio_ord,
+        transcode,
+        s.hw,
+        s.tonemap,
     )
     return s
 
@@ -325,10 +714,14 @@ def current_session(key: str) -> HlsSession | None:
         return s
 
 
-def wait_for(path: Path, timeout: float = 20.0) -> bool:
+def wait_for(path: Path, timeout: float = 20.0, proc: subprocess.Popen | None = None) -> bool:
     """Wait until a session file (playlist / segment) exists and is non-empty. Segments are
     produced ~faster than realtime, so a segment just ahead of playback appears quickly; a segment
-    far beyond the generated region won't (the frontend restarts the session at a seek instead)."""
+    far beyond the generated region won't (the frontend restarts the session at a seek instead).
+
+    With `proc` given, also stop as soon as that ffmpeg exits: a VAAPI session that fails to init
+    (10-bit/HDR VAProfile refusal) dies within ~1s producing nothing, and without this we'd block the
+    whole `timeout` before the HW→SW fallback could kick in — turning the fix into a stall."""
     end = time.time() + timeout
     while time.time() < end:
         try:
@@ -336,6 +729,12 @@ def wait_for(path: Path, timeout: float = 20.0) -> bool:
                 return True
         except OSError:
             pass
+        if proc is not None and proc.poll() is not None:
+            # the producer exited — no more segments are coming; one last check then give up.
+            try:
+                return path.exists() and path.stat().st_size > 0
+            except OSError:
+                return False
         time.sleep(0.15)
     return path.exists()
 

backend/app/plex/sync.py

@@ -18,7 +18,7 @@ item-detail/player path (P2), not here.
 import logging
 from datetime import datetime, timezone
 
-from sqlalchemy import select
+from sqlalchemy import func, select
 from sqlalchemy.orm import Session
 
 from app import sysconfig
@@ -58,6 +58,57 @@ def classify_playable(vcodec: str | None, acodec: str | None, container: str | N
     return "direct"
 
 
+# Video codecs the prod iGPU (UHD 630 / Quick Sync Gen 9.5) can hardware-DECODE — the precondition for
+# the full-GPU VAAPI transcode pipeline. THE single source of this set: plex.stream imports it here so
+# the runtime encoder choice (`_want_hw`) and this catalog facet can never disagree by codec. A source
+# outside it (AV1, MPEG-4 ASP/XviD…) is software-only even on the iGPU (it can't decode it to feed its
+# own encoder).
+HW_DECODABLE_CODECS = frozenset({"h264", "hevc", "h265", "vp9", "vc1", "mpeg2video"})
+# Color-transfer values marking an HDR source (PQ / HLG). A 10-bit/HDR source breaks the VAAPI
+# scale=nv12 path on Gen 9.5 (see plex.stream) → software transcode, so it counts as NOT HW-capable.
+_HDR_TRANSFERS = frozenset({"smpte2084", "arib-std-b67"})
+
+
+def transcode_hw_capable(
+    playable: str | None,
+    vcodec: str | None,
+    bit_depth: int | None = None,
+    hdr: bool = False,
+) -> bool | None:
+    """The stored `PlexItem.transcode_hw` facet: for a `playable="transcode"` item, whether the prod
+    iGPU can HARDWARE-transcode it (else software libx264 only); None for a non-transcode item. HW needs
+    a HW-decodable codec AND an 8-bit SDR source — a 10-bit/HDR source (bit_depth>8 or an HDR transfer)
+    breaks the VAAPI nv12 pipeline and falls back to software. `bit_depth`/`hdr` are unknown at sync
+    time (the cheap listing carries no Stream), so they default to 8-bit SDR (codec-only) and the
+    bit-depth backfill refines a 10-bit/HDR HEVC to False later."""
+    if playable != "transcode":
+        return None
+    if (vcodec or "").lower() not in HW_DECODABLE_CODECS:
+        return False
+    if bit_depth is not None and bit_depth > 8:
+        return False
+    return not hdr
+
+
+def _video_stream_props(meta: dict) -> tuple[int | None, bool]:
+    """(bit_depth, is_hdr) from a FULL Plex metadata dict's video Stream (Media→Part→Stream, streamType
+    1). Only the rich metadata call carries Stream; the cheap listing does not — so this is read by the
+    bit-depth backfill, not the listing sync. (None, False) when absent/unparseable."""
+    for m in meta.get("Media") or []:
+        for part in m.get("Part") or []:
+            for s in part.get("Stream") or []:
+                if s.get("streamType") != 1:  # 1 = video
+                    continue
+                bd = s.get("bitDepth")
+                try:
+                    depth = int(bd) if bd else None
+                except (TypeError, ValueError):
+                    depth = None
+                hdr = str(s.get("colorTrc") or "").lower() in _HDR_TRANSFERS
+                return depth, hdr
+    return None, False
+
+
 def _epoch(v) -> datetime | None:
     try:
         return datetime.fromtimestamp(int(v), tz=timezone.utc) if v else None
@@ -217,6 +268,13 @@ def sync(db: Session) -> dict:
                 stats["people_enriched"] = _enrich_people_batch(db, plex)
             except Exception as e:  # best-effort — never fail the sync over the backfill
                 log.warning("Plex people enrich batch failed: %s", e)
+            # Probe a bounded batch of HW-decodable transcode items for bit-depth/HDR, so the
+            # playback-class filter's HW/SW split is precise (a 10-bit/HDR HEVC → software) over
+            # successive runs. Only HW-decodable-codec transcodes are probed — the rest are SW by codec.
+            try:
+                stats["media_probed"] = _probe_media_batch(db, plex)
+            except Exception as e:  # best-effort — never fail the sync over the backfill
+                log.warning("Plex media probe batch failed: %s", e)
     except PlexNotConfigured as e:
         return {"skipped": str(e)}
     except PlexError as e:
@@ -236,6 +294,49 @@ def sync(db: Session) -> dict:
 # How many titles to rich-fetch per sync run for the cast backfill — bounds the extra Plex load; the
 # whole library is covered over successive runs (each fetched item is stamped people_enriched_at once).
 _ENRICH_BATCH = 60
+# Same bounded-per-run pattern for the bit-depth probe. Only HW-decodable-codec transcode items are
+# probed (typically a small minority — the bulk of transcodes are old codecs that are SW by codec), so
+# a modest batch covers the work-list in a run or two; a stuck item retries next run (watermark unset).
+_PROBE_BATCH = 60
+
+
+def _probe_media_batch(db: Session, plex: PlexClient, limit: int = _PROBE_BATCH) -> int:
+    """Rich-fetch up to `limit` not-yet-probed HW-decodable transcode items, read the video Stream's
+    bit-depth + HDR, and store `video_bit_depth` + the refined `transcode_hw` (a 10-bit/HDR HEVC →
+    False/software). Stamps `media_probed_at` on every attempt (success OR a Plex miss with no Stream),
+    so an item is probed once and not re-fetched every sync; a transient fetch FAILURE leaves the
+    watermark unset to retry. Oldest-id first. Returns how many items were probed this run."""
+    rows = (
+        db.execute(
+            select(PlexItem)
+            .where(
+                PlexItem.playable == "transcode",
+                func.lower(PlexItem.codec_video).in_(HW_DECODABLE_CODECS),
+                PlexItem.media_probed_at.is_(None),
+            )
+            .order_by(PlexItem.id)
+            .limit(limit)
+        )
+        .scalars()
+        .all()
+    )
+    now = datetime.now(timezone.utc)
+    n = 0
+    for row in rows:
+        try:
+            meta = plex.metadata(row.rating_key) or {}
+        except Exception as e:  # transient — leave media_probed_at NULL so it retries next run
+            log.debug("Plex media probe fetch failed for %s: %s", row.rating_key, e)
+            continue
+        bit_depth, hdr = _video_stream_props(meta)
+        row.video_bit_depth = bit_depth
+        row.transcode_hw = transcode_hw_capable("transcode", row.codec_video, bit_depth, hdr)
+        row.media_probed_at = (
+            now  # probed (even if Plex carried no Stream — don't re-fetch forever)
+        )
+        n += 1
+    db.commit()
+    return n
 
 
 def _enrich_people_batch(db: Session, plex: PlexClient, limit: int = _ENRICH_BATCH) -> int:
@@ -369,15 +470,41 @@ def _apply_item(row: PlexItem, lib_id: int, kind: str, meta: dict) -> None:
     row.added_at = _epoch(meta.get("addedAt"))
     _apply_facet_fields(row, meta)  # filterable/orderable extras (shared with shows)
     mf = _media_facts(meta)
+    new_vcodec = mf.get("codec_video")
+    new_part_key = mf.get("part_key")
+    # The physical file was replaced when its video codec changes OR — for a SINGLE-version item — when its
+    # Plex Part key changes (a re-encode / quality upgrade gets a new part id). Either way any probed
+    # bit-depth is stale, so reset the probe watermark and re-derive transcode_hw from codec alone until the
+    # backfill re-probes. Codec alone is NOT enough: a same-codec bit-depth re-encode (8-bit→10-bit HEVC)
+    # keeps the codec `hevc` but flips the HW class, and only the part-key move catches it.
+    #
+    # The part-key check is gated on single-version because `_media_facts` reads media[0]/part[0], and for a
+    # MULTI-version item (an original + a Plex "Optimized" copy) that order isn't guaranteed stable across
+    # listings — an unguarded part-key compare would then reset+re-probe every sync and oscillate the
+    # transcode_hw bucket between the two versions. A multi-version same-codec re-encode not self-healing is
+    # an acceptable rare edge; a per-sync re-probe loop is not.
+    single_version = len(meta.get("Media") or []) <= 1
+    codec_changed = (row.codec_video or "").lower() != (new_vcodec or "").lower()
+    if codec_changed or (single_version and row.part_key != new_part_key):
+        row.video_bit_depth = None
+        row.media_probed_at = None
     row.file_path = mf.get("file_path")
-    row.part_key = mf.get("part_key")
+    row.part_key = new_part_key
     row.container = mf.get("container")
-    row.codec_video = mf.get("codec_video")
+    row.codec_video = new_vcodec
     row.codec_audio = mf.get("codec_audio")
     row.size_bytes = mf.get("size_bytes")
     row.playable = classify_playable(
         mf.get("codec_video"), mf.get("codec_audio"), mf.get("container")
     )
+    # transcode_hw: keep the bit-depth backfill's authoritative value (it folds in bit-depth + HDR) once
+    # probed; otherwise (re)derive the provisional codec-only class. A non-transcode item is always None,
+    # even if it had been probed as a transcode before (an audio/container flip to remux without a codec
+    # change wouldn't reset the watermark, so pin it here).
+    if row.playable != "transcode":
+        row.transcode_hw = None
+    elif row.media_probed_at is None:
+        row.transcode_hw = transcode_hw_capable("transcode", row.codec_video, row.video_bit_depth)
 
 
 def _prune_stale(

backend/app/plex/watch_sync.py

@@ -11,11 +11,14 @@ already pages) and upsert them into the owner's `plex_states`. Plex wins on over
 exist only in Siftlode are left untouched (union, Plex-authoritative on the intersection).
 
 Phases B (Siftlode→Plex push via scrobble/timeline) and C (incremental Plex→Siftlode via the watch
-history + onDeck, last-write-wins) build on this and land in later ships.
+history + onDeck) build on this and land in later ships. As of S2 Plex is the source of truth: the
+player pushes the resume position back to Plex on the periodic checkpoint (not just the final flush),
+and the incremental pull resolves a genuine divergence to Plex's state (see `_pull_apply`) rather than
+running a last-write-wins comparison.
 """
 
 import logging
-from datetime import datetime, timedelta, timezone
+from datetime import datetime, timezone
 
 from sqlalchemy import func, select, update
 from sqlalchemy.dialects.postgresql import insert as pg_insert
@@ -293,12 +296,6 @@ def push_bulk_state_to_plex(user_id: int, changes: list[tuple[int, str, str]]) -
 
 # --- Phase C: incremental + full Plex ↔ Siftlode reconcile (scheduler jobs) ------------------------
 
-# Clock-skew / round-trip slack when comparing a Plex timestamp to a Siftlode one. A state we just
-# pushed (Plex stamps viewedAt a beat after our watched_at) must not read as "newer on Plex" and get
-# pulled back with a different shape. Genuine Plex-side edits are minutes from our writes — far
-# outside this — so the window only absorbs skew, never real changes.
-_LWW_TOLERANCE_S = 90
-
 
 def _active_sync_links(db: Session) -> list[PlexLink]:
     """Every link with two-way sync actually running (owner MVP = one row). Iterated uniformly so
@@ -338,11 +335,6 @@ def _resolve_account_id(db: Session, plex: PlexClient, link: PlexLink) -> int:
     return acct_id
 
 
-def _sift_ts(st: PlexState) -> datetime | None:
-    """The freshest Siftlode-side timestamp on a row, for last-write-wins."""
-    return max([t for t in (st.watched_at, st.progress_updated_at) if t], default=None)
-
-
 def _same_state(st: PlexState | None, status: str, pos: int) -> bool:
     """Whether a row already matches a target (status, pos) — the core ping-pong guard: when nothing
     would change we skip the write entirely (no row churn, no timestamp bump, no re-pull)."""
@@ -370,9 +362,20 @@ def _pull_apply(
         if st is not None and not st.synced_to_plex:
             st.synced_to_plex = True  # already matches Plex → just settle the flag, no churn
         return None
-    # Conflict: keep Siftlode when it's newer than Plex (plus skew slack).
-    sts = _sift_ts(st) if st else None
-    if sts and plex_ts and plex_ts <= sts + timedelta(seconds=_LWW_TOLERANCE_S):
+    # Plex-authoritative (S2): on a genuine divergence for an item Plex knows about, Plex wins — no
+    # last-write-wins tug-of-war. This is safe because prompt write-back (playback.py pushes the resume
+    # position to Plex on the ~10s checkpoint, not just on the final flush) keeps Plex current, so a
+    # local edit that's "newer" than Plex has almost always already been pushed and matched above by
+    # `_same_state`; a row that reaches here really is out of step with the source of truth. The
+    # `_same_state` + `synced_to_plex` short-circuit above still absorbs the freshly-pushed case (Plex
+    # echoes the same shape a beat later) so a just-pushed row never bounces.
+    if st is not None and not st.synced_to_plex:
+        # Durability guard: this row holds a local change that never reached Plex — its immediate push
+        # failed, so it's still dirty. Do NOT let the Plex-authoritative pull overwrite it and clear the
+        # flag: that would strand the local value forever, since `_repush_dirty` only retries dirty rows.
+        # Leave it dirty; `_repush_dirty` (later in this same run) pushes the local value up to Plex. This
+        # closes the "Plex flapped mid-session" lost-update — the one case the Plex-wins comment's
+        # "almost always already pushed" assumption above excludes.
         return None
     if st is None:
         st = PlexState(user_id=user_id, item_id=item_id)
@@ -436,14 +439,89 @@ def _repush_dirty(db: Session, plex: PlexClient, link: PlexLink) -> int:
     return n
 
 
+# How many stale in-progress movies we probe per incremental run (one metadata() call each). The set
+# is normally tiny (movies started but no longer on Plex's Continue-Watching); the daily full reconcile
+# is the backstop for anything beyond the cap. Most-recently-touched are probed first.
+_MOVIE_PROBE_CAP = 100
+
+
+def _reconcile_inprogress_movies(
+    db: Session, plex: PlexClient, link: PlexLink, on_deck_ids: set[int]
+) -> dict[str, int]:
+    """Close the movie "stuck in progress" gap that the history + onDeck feeds structurally miss.
+
+    When a movie is finished on Plex (often by scrubbing through the end credits) Plex sets
+    ``viewCount>0``, clears ``viewOffset`` and DROPS the movie from Continue-Watching. So onDeck no
+    longer lists it (and onDeck can only ever ADD an in-progress row, never resolve one to watched —
+    see `_pull_apply`), and a scrub-to-end frequently emits no `/status/sessions/history` session row,
+    so the history feed misses it too. The stale local ``status='new', position>0`` row then survives
+    until the *daily* full reconcile. Movies are hit hardest: a movie is a single leaf with no
+    episode-rollup to mask the stuck row, and once watched it leaves onDeck entirely.
+
+    Fix: for each local in-progress MOVIE that Plex's onDeck no longer lists, read the item's current
+    per-(token-)account ``viewCount``/``viewOffset`` with one cheap `metadata()` call and apply it via
+    the shared `_pull_apply` — flipping to watched when Plex says so. Returns ``{"watched", "in_progress",
+    "probed"}`` counts. Episodes are intentionally left to onDeck/history (they promote the next episode
+    and aren't affected). Note: like the rest of this job, `metadata()` reads the TOKEN account (the
+    owner) — a HTPC playing under a managed Plex user (accountID>1) is out of scope here as elsewhere."""
+    conds = [
+        PlexState.user_id == link.user_id,
+        PlexState.status.notin_(("watched", "hidden")),
+        PlexState.position_seconds > _PROGRESS_MIN_S,
+        PlexItem.kind == "movie",
+    ]
+    if on_deck_ids:
+        conds.append(PlexState.item_id.notin_(on_deck_ids))
+    rows = db.execute(
+        select(PlexState, PlexItem.rating_key)
+        .join(PlexItem, PlexItem.id == PlexState.item_id)
+        .where(*conds)
+        .order_by(PlexState.progress_updated_at.desc().nullslast())
+        .limit(_MOVIE_PROBE_CAP + 1)
+    ).all()
+    if len(rows) > _MOVIE_PROBE_CAP:
+        rows = rows[:_MOVIE_PROBE_CAP]
+        log.warning(
+            "in-progress movie probe hit the %d cap (user %s); reconcile catches the tail",
+            _MOVIE_PROBE_CAP,
+            link.user_id,
+        )
+    out = {"watched": 0, "in_progress": 0, "probed": 0}
+    for st, rk in rows:
+        try:
+            meta = plex.metadata(rk)
+        except PlexError as e:
+            log.warning(
+                "movie watch-probe failed (user %s, item %s): %s", link.user_id, st.item_id, e
+            )
+            continue
+        out["probed"] += 1
+        if meta is None:
+            continue
+        res = _plex_watch_to_state(
+            meta.get("viewCount"), meta.get("viewOffset"), meta.get("lastViewedAt")
+        )
+        if res is None:
+            # Plex holds no watch signal now (viewCount 0, no offset) — don't clear it here; an un-watch
+            # is the daily reconcile's job, and a Siftlode-only in-progress row must be preserved.
+            continue
+        status, pos, watched_at, prog_at = res
+        ch = _pull_apply(db, link.user_id, st.item_id, status, pos, watched_at or prog_at)
+        if ch:
+            out[ch] += 1
+    return out
+
+
 def run_plex_watch_sync(db: Session) -> dict:
-    """Scheduler job (default 30 min) — the cheap incremental pass. Pulls Plex-side changes since the
-    high-water mark (watch history + on-deck, filtered to the owner account) into Siftlode under
-    last-write-wins, then re-pushes any still-unsynced local states. Does NOT propagate un-watches
-    (the history feed only carries positive views) — that's `run_plex_watch_reconcile`'s job."""
+    """Scheduler job (default 15 min) — the cheap incremental pass. Pulls Plex-side changes since the
+    high-water mark (watch history + on-deck, filtered to the owner account) into Siftlode, resolving a
+    divergence to Plex (the source of truth — see `_pull_apply`), reconciles stale in-progress movies
+    Plex has since finished (see `_reconcile_inprogress_movies`), then re-pushes any still-unsynced
+    local states. Does NOT propagate un-watches (the history feed only carries positive views) — that's
+    `run_plex_watch_reconcile`'s job."""
     if not sysconfig.get_bool(db, "plex_enabled"):
         return {"skipped": "disabled"}
-    total = {"links": 0, "watched": 0, "in_progress": 0, "repushed": 0}
+    total = {"links": 0, "watched": 0, "in_progress": 0, "repushed": 0, "movie_probes": 0}
     for link in _active_sync_links(db):
         total["links"] += 1
         try:
@@ -463,10 +541,14 @@ def run_plex_watch_sync(db: Session) -> dict:
                     if ch:
                         total[ch] += 1
 
+                # onDeck resolves resume-position changes AND tells us which items Plex still considers
+                # in-progress (needed by the movie reconcile below to know which local rows are stale).
+                on_deck_ids: set[int] = set()
                 for row in plex.on_deck():
                     iid = rk_to_id.get(str(row.get("ratingKey") or ""))
                     if iid is None:
                         continue
+                    on_deck_ids.add(iid)
                     off = int(row.get("viewOffset") or 0) // 1000
                     if off < _PROGRESS_MIN_S:
                         continue
@@ -476,6 +558,11 @@ def run_plex_watch_sync(db: Session) -> dict:
                     if ch:
                         total[ch] += 1
 
+                mv = _reconcile_inprogress_movies(db, plex, link, on_deck_ids)
+                total["watched"] += mv["watched"]
+                total["in_progress"] += mv["in_progress"]
+                total["movie_probes"] += mv["probed"]
+
                 total["repushed"] += _repush_dirty(db, plex, link)
                 link.last_watch_sync_at = now
                 db.commit()
@@ -491,7 +578,7 @@ def run_plex_watch_sync(db: Session) -> dict:
 def run_plex_watch_reconcile(db: Session) -> dict:
     """Scheduler job (default daily) — the authoritative full reconcile. Rescans every section and,
     per item, uses `synced_to_plex` to settle what the incremental feed can't:
-      - Plex has a state, Siftlode differs → last-write-wins (Plex usually the newer here).
+      - Plex has a state, Siftlode differs → Plex wins (the source of truth — see `_pull_apply`).
       - Siftlode has a state, Plex has NO record:
           · synced_to_plex=True  → Plex un-watched it since our last sync → clear it (un-watch).
           · synced_to_plex=False → a local change that never reached Plex → re-push it (via

backend/app/ratelimit.py

@@ -18,6 +18,13 @@ class RateLimiter:
         self._hits: dict[str, list[float]] = {}
         self._lock = threading.Lock()
 
+    def reset(self) -> None:
+        """Forget every recorded attempt. Each limiter is a module-level singleton, so a test suite
+        sharing one process would otherwise pool all of its attempts into a single window and
+        eventually trip an unrelated test with a 429."""
+        with self._lock:
+            self._hits.clear()
+
     def allow(self, key: str) -> bool:
         """Record an attempt for ``key`` and return whether it is within the limit.
 

backend/app/routes/admin.py

@@ -1,20 +1,26 @@
 """Admin-only onboarding: review access requests (Invites), approve/deny, manual add.
 Also the demo-account admin surface: the demo email whitelist + a manual state reset."""
 
+from collections.abc import Iterable
 from datetime import datetime, timezone
 
 from fastapi import APIRouter, BackgroundTasks, Depends, HTTPException
 from pydantic import BaseModel
-from sqlalchemy import select
+from sqlalchemy import or_, select
 from sqlalchemy.orm import Session
 
 from app import audit
 from app import email as email_mod
+from app import mailtext
 from app.audit import AuditAction
 from app.auth import (
     admin_user,
+    can_activate,
     count_admins,
+    env_allowed_canonicals,
+    find_user_by_email,
     get_or_create_demo_user,
+    is_allowed,
     operator_contact,
     purge_user,
 )
@@ -25,13 +31,42 @@ from app.models import (
     Invite,
     User,
 )
-from app.routes.auth import revoke_preset_password_if_unverified
-from app.utils import iso, valid_email
+from app.routes._common import get_or_404
+from app.routes.auth import APPROVAL_VERIFY_TTL, issue_verification_link, send_verification_link
+from app.utils import canonical_email, iso, valid_email
 
 router = APIRouter(prefix="/api/admin", tags=["admin"])
 
 
-def _serialize(inv: Invite) -> dict:
+def _accounts_for(db: Session, emails: Iterable[str]) -> set[str]:
+    """Which of these addresses already have an account, as a set of CANONICAL forms. Batched, so
+    listing the invites costs one extra query. An invite whose address has an account must not be
+    deletable: `is_allowed` reads this row, so removing it would silently revoke a live user's access.
+
+    Canonical on both sides, because `is_allowed` matches that way: an invite for `x.y@gmail.com`
+    whose account registered as `xy@gmail.com` would otherwise look account-less, offer the admin a
+    delete button, and take away a live user's access — precisely the accident this guard exists to
+    prevent."""
+    wanted = {canonical_email(e) for e in emails if e}
+    if not wanted:
+        return set()
+    rows = db.execute(
+        select(User.email_canonical).where(User.email_canonical.in_(wanted))
+    ).scalars()
+    return {e for e in rows if e}
+
+
+def _env_allowed(email: str) -> bool:
+    """Whether the env bootstrap lists still let this address in. `is_allowed` consults them only
+    when no Invite row exists, so this is exactly what deleting the row would fall back to — and the
+    admin has to know that BEFORE they confirm, not from a toast afterwards.
+
+    Canonical, because `is_allowed` is: a warning that disagrees with the gate it is warning about is
+    worse than no warning."""
+    return canonical_email(email or "") in env_allowed_canonicals()
+
+
+def _serialize(inv: Invite, *, has_account: bool = False) -> dict:
     return {
         "id": inv.id,
         "email": inv.email,
@@ -40,6 +75,19 @@ def _serialize(inv: Invite) -> dict:
         "requested_at": iso(inv.requested_at),
         "decided_at": iso(inv.decided_at),
         "decided_by": inv.decided_by,
+        # When (if ever) the admin sent this person an invitation. Adding an address is silent, so
+        # without this the admin has no way to answer "did I already write to them?" — and the only
+        # failure mode is writing to a real person twice.
+        "invited_at": iso(inv.invited_at),
+        # Drives the delete affordance: an entry backed by an account is not removable here.
+        "has_account": has_account,
+        # …and whether removing it would actually take access away, or leave the env allow-list
+        # granting it anyway (for an ADMIN_EMAILS address, as an admin).
+        "still_allowed_by_env": _env_allowed(inv.email),
+        # The language this person asked us in, or null when nobody ever told us (a hand-added
+        # whitelist row). The invitation dialog preselects it, and falls back to the admin's own UI
+        # language — a guess, but a visible one the admin can correct before sending.
+        "lang": inv.lang,
     }
 
 
@@ -56,18 +104,65 @@ def list_invites(
     rows = db.execute(stmt.order_by(Invite.requested_at.desc())).scalars().all()
     order = {"pending": 0, "approved": 1, "denied": 2}
     rows.sort(key=lambda i: order.get(i.status, 9))
-    return [_serialize(i) for i in rows]
+    accounts = _accounts_for(db, (i.email for i in rows))
+    return [_serialize(i, has_account=canonical_email(i.email) in accounts) for i in rows]
+
+
+def _welcome_mail_parts(db: Session, email: str) -> tuple[str | None, bool, int]:
+    """What a welcome or invitation mail should tell this address to do next: a confirmation link (if
+    there is an unconfirmed account behind it), whether an account exists at all, and how long the
+    link lasts.
+
+    This is the C option's whole mechanic. In the common ordering — the address is approved and the
+    person signs up either side of that — they would otherwise have to find and open TWO messages:
+    one saying they are in, another asking them to confirm. Carrying the link inside the mail that is
+    already going out makes it one mail and one click.
+
+    Resolved through `find_user_by_email`, so an account registered under another spelling of the
+    same Gmail mailbox is still recognised — and, deliberately, so several candidates resolve to
+    "no single answer" rather than a guess: an invitation that carried the wrong account's link would
+    be worse than one that simply pointed at the sign-up page.
+    """
+    hours = int(APPROVAL_VERIFY_TTL.total_seconds() // 3600)
+    user = find_user_by_email(db, email)
+    if user is None or user.is_demo:
+        return None, False, hours
+    if user.email_verified or not email_mod.email_enabled(db):
+        return None, True, hours
+    return issue_verification_link(db, user, APPROVAL_VERIFY_TTL), True, hours
 
 
 def _activate_user_by_email(db: Session, email: str) -> None:
     """Approving access activates a matching (e.g. pending password-registration) account so
-    it can sign in. No-op if no such user exists yet (a Google user is created at first login)."""
-    user = db.execute(select(User).where(User.email == email.lower())).scalar_one_or_none()
+    it can sign in. No-op if no such user exists yet (a Google user is created at first login).
+
+    E9.5 S1: this path deliberately does NOT revoke a preset password. Revoking here destroyed the
+    password a legitimate registrant had just chosen and made "your password was cleared for
+    security" the DEFAULT experience, because approve-before-verify is the normal ordering.
+
+    S1 justified that by saying `password_login` refuses an unverified account BEFORE it looks at
+    `is_active`, so a pre-emptor could not sign in "approved or not". A review of the finished epic
+    showed that argument only holds while the address stays unverified — and S6's approval mail
+    hands the real owner a confirmation link precisely so they will end that state. Nothing replaced
+    the revoke, and that is deliberate: round 2 of the same review tried "the newest registration
+    owns an unverified account" and reverted it, because the rule is symmetric — an attacker can
+    always register last — and it handed anonymous callers a write onto a real account's credential.
+    The owner's recourse is password-reset, which proves the mailbox, rewrites the hash and bumps
+    the session epoch. The residual is logged as SEC-16. The revoke also stays on the Google-adoption path
+    (auth.revoke_preset_password_if_unverified), where ownership is actually attested."""
+    # Canonical, with the literal spelling preferred when both exist: approving
+    # `npeter83.temu@gmail.com` must activate the account that registered as `npeter83temu@gmail.com`,
+    # since Gmail delivers both to one mailbox and the admin decided about the mailbox.
+    email = email.lower()
+    candidates = (
+        db.execute(
+            select(User).where(User.email_canonical == canonical_email(email)).order_by(User.id)
+        )
+        .scalars()
+        .all()
+    )
+    user = next((u for u in candidates if u.email == email), None) or next(iter(candidates), None)
     if user is not None and not user.is_active:
-        # SEC-10: same guard as the Google-adoption path — approving an account whose email was never
-        # verified must not hand a working login to a password set on it by whoever registered the
-        # address (a pre-emption). Shared single-source helper so the two paths can't drift.
-        revoke_preset_password_if_unverified(user)
         user.is_active = True
         db.commit()
 
@@ -106,8 +201,13 @@ def approve_invite(
 ) -> dict:
     inv = _decide(db, invite_id, admin, approved=True)
     _activate_user_by_email(db, inv.email)
-    background.add_task(email_mod.send_access_approved, inv.email)
-    return _serialize(inv)
+    # Computed here, not in the background task: issuing the token needs this request's session, and
+    # the task must not outlive it. Approval answers a request the person MADE, so unlike the
+    # invitation below it is sent automatically — a reply is owed, not a nudge.
+    link, has_account, hours = _welcome_mail_parts(db, inv.email)
+    lang = mailtext.lang_for_email(db, inv.email)
+    background.add_task(email_mod.send_access_approved, inv.email, lang, link, has_account, hours)
+    return _serialize(inv, has_account=bool(_accounts_for(db, [inv.email])))
 
 
 @router.post("/invites/{invite_id}/deny")
@@ -120,8 +220,10 @@ def deny_invite(
     # Symmetry with approve: the requester hears back either way, instead of a silent limbo. No
     # account is activated, so this is an email only (the requester has no in-app inbox yet).
     inv = _decide(db, invite_id, admin, approved=False)
-    background.add_task(email_mod.send_access_denied, inv.email)
-    return _serialize(inv)
+    background.add_task(
+        email_mod.send_access_denied, inv.email, mailtext.lang_for_email(db, inv.email)
+    )
+    return _serialize(inv, has_account=bool(_accounts_for(db, [inv.email])))
 
 
 class AddInviteIn(BaseModel):
@@ -138,7 +240,16 @@ def add_invite(
     email = body.email.strip().lower()
     if not valid_email(email):
         raise HTTPException(status_code=400, detail="Enter a valid email address.")
-    inv = db.execute(select(Invite).where(Invite.email == email)).scalar_one_or_none()
+    # Reuse a canonically-equal row instead of adding a second one for the same mailbox. Prod carries
+    # exactly that pair for one person from 2026-06-16 (hartmann.peter1986@ / hartmannpeter1986@),
+    # which is how an admin ends up approving the same human twice and still seeing them bounce.
+    canon = canonical_email(email)
+    rows = (
+        db.execute(select(Invite).where(Invite.email_canonical == canon).order_by(Invite.id))
+        .scalars()
+        .all()
+    )
+    inv = next((r for r in rows if r.email == email), None) or next(iter(rows), None)
     if inv is None:
         inv = Invite(email=email)
         db.add(inv)
@@ -150,7 +261,126 @@ def add_invite(
     )
     db.commit()
     _activate_user_by_email(db, email)
-    return _serialize(inv)
+    return _serialize(inv, has_account=bool(_accounts_for(db, [email])))
+
+
+class InviteSendIn(BaseModel):
+    # Which language to write this person in. Optional so an existing caller (and a test) can post
+    # an empty body, but the admin UI always sends it: this is the one recipient the app has no
+    # signal about, because the admin typed the address in themselves.
+    lang: str | None = None
+
+
+@router.post("/invites/{invite_id}/invite")
+def send_invitation(
+    invite_id: int,
+    body: InviteSendIn | None = None,
+    admin: User = Depends(admin_user),
+    db: Session = Depends(get_db),
+) -> dict:
+    """Tell someone their address is whitelisted — only when the admin asks for it.
+
+    Whitelisting stays SILENT on purpose. The operator opens a door as a possibility, usually having
+    already agreed it with the person, and an address can sit approved for weeks with nobody
+    registering; a mail fired automatically would be nudging someone who never asked to be nudged.
+    So the send is its own act, on its own button, and `invited_at` records it so the admin can see
+    they have already written rather than writing twice.
+
+    Only an APPROVED row can be invited: there is nothing to invite someone to while their request is
+    undecided, and inviting a denied address would contradict the decision."""
+    inv = get_or_404(db, Invite, invite_id, detail="No such invite")
+    if inv.status != "approved":
+        raise HTTPException(
+            status_code=409,
+            detail={"code": "invite_send", "reason": "not_approved", "email": inv.email},
+        )
+    if not email_mod.email_enabled(db):
+        # Same reasoning as the admin-side verification resend: mail is fail-soft everywhere else,
+        # but a button the admin pressed must not answer with a success toast for a mail that was
+        # never sent.
+        raise HTTPException(status_code=409, detail={"code": "invite_send", "reason": "email_off"})
+    link, has_account, hours = _welcome_mail_parts(db, inv.email)
+    # An explicit pick from the dialog is recorded, so a later mail to this address matches the one
+    # the admin already sent. Only the explicit pick — writing the fallback back would turn a column
+    # that means "what this person told us" into "what we last guessed".
+    picked = body.lang if body else None
+    if picked in mailtext.SUPPORTED:
+        lang = inv.lang = picked
+    else:
+        lang = mailtext.lang_for_email(db, inv.email)
+    # Sent INLINE, so `invited_at` records the send rather than the intent. Every other mail here is
+    # fail-soft in the background, which is right when nobody is waiting on it — but this column
+    # exists to answer "did I already write to them?", and the UI dims the button and warns about a
+    # second mail on the strength of it. Stamping it before a send that then failed makes the one
+    # question it answers a lie, and talks the admin out of the retry that would fix it.
+    #
+    # One thing a failed send does leave behind: the confirmation token `_welcome_mail_parts` minted
+    # to render the link, which commits inside `_issue_token`. Accepted rather than chased — the
+    # token is single-use, expires on its own, and was mailed nowhere; deferring it would mean
+    # rewriting a helper three callers share so the handler owns its commit.
+    if not email_mod.send_access_invitation(inv.email, lang, link, has_account, hours):
+        raise HTTPException(
+            status_code=422, detail={"code": "invite_send", "reason": "send_failed"}
+        )
+    # Only after the mail is actually out. Same as the other two paths that decide for an address
+    # (`approve_invite`, `add_invite`): an approved row means this mailbox may come in, so finish it,
+    # or the mail can promise "your account is ready — just sign in" to someone `password_login` will
+    # refuse for `is_active`. Doing it BEFORE the send would mean a request the UI reports as failed
+    # had quietly activated an account behind the admin's back.
+    _activate_user_by_email(db, inv.email)
+    inv.invited_at = datetime.now(timezone.utc)
+    audit.record(
+        db,
+        admin.id,
+        AuditAction.INVITE_SEND,
+        target_type="invite",
+        target_id=inv.id,
+        summary=inv.email,
+    )
+    db.commit()
+    return _serialize(inv, has_account=has_account)
+
+
+@router.delete("/invites/{invite_id}")
+def delete_invite(
+    invite_id: int,
+    admin: User = Depends(admin_user),
+    db: Session = Depends(get_db),
+) -> dict:
+    """Remove a whitelist/request entry outright — the counterpart to add_invite, for an address that
+    never became an account (an approval added by mistake, or one that is no longer wanted). Deny
+    records a decision and keeps the row for the audit trail; delete forgets the address. Neither
+    stops the person asking again: `upsert_pending_invite` reopens a denied row, and a deleted one
+    simply comes back as a fresh pending request.
+
+    Refused once an account exists for the address, whatever its state: this row is the account's
+    approval gate, and orphaning the account from it would leave a person who can neither sign in nor
+    be approved. Delete the USER instead — purge_user removes the invite along with it.
+
+    Reports `still_allowed_by_env`, because deleting the row is NOT always a revoke: `is_allowed`
+    falls back to the env ALLOWED_EMAILS / ADMIN_EMAILS bootstrap lists once no invite exists, so for
+    an address on those the deletion leaves access intact (and an ADMIN_EMAILS address is still
+    promoted to admin on its next Google sign-in). The admin has to hear that, not guess it."""
+    inv = db.get(Invite, invite_id)
+    if inv is None:
+        raise HTTPException(status_code=404, detail="No such invite")
+    if _accounts_for(db, [inv.email]):
+        raise HTTPException(
+            status_code=409,
+            detail="That address already has an account — delete the account instead.",
+        )
+    still_allowed_by_env = _env_allowed(inv.email)
+    audit.record(
+        db,
+        admin.id,
+        AuditAction.INVITE_DELETE,
+        target_type="invite",
+        target_id=inv.id,
+        summary=inv.email,
+    )
+    db.delete(inv)
+    db.commit()
+    return {"deleted": invite_id, "still_allowed_by_env": still_allowed_by_env}
 
 
 # --- Users & roles --------------------------------------------------------------------
@@ -224,7 +454,13 @@ def set_user_role(
     target.role = role
     db.commit()
     if changed:
-        background.add_task(email_mod.send_role_changed, target.email, role, operator_contact())
+        background.add_task(
+            email_mod.send_role_changed,
+            target.email,
+            mailtext.lang_for_user(target),
+            role,
+            operator_contact(),
+        )
     return _serialize_user(target)
 
 
@@ -273,7 +509,12 @@ def set_user_suspended(
     target.is_suspended = suspended
     db.commit()
     if was_suspended and not suspended:
-        background.add_task(email_mod.send_account_unsuspended, target.email, operator_contact())
+        background.add_task(
+            email_mod.send_account_unsuspended,
+            target.email,
+            mailtext.lang_for_user(target),
+            operator_contact(),
+        )
     return _serialize_user(target)
 
 
@@ -318,6 +559,140 @@ def admin_delete_user(
 # --- Demo account: email whitelist + state reset -------------------------------------
 
 
+# --- Stuck sign-ups: the admin lifeline (E9.5 S5, roadmap UX-25) ---------------------------------
+
+
+def _pending_access_rows(db: Session) -> list[User]:
+    """Accounts that have signed up but still cannot sign in, newest first.
+
+    Two different dead ends share this list, because from the admin's chair they look the same — a
+    person who registered and is still outside:
+      · `is_active=False` — approved BEFORE they signed up, so nothing ever landed in the
+        Access-requests queue and its Approve button doesn't apply (`_decide` only takes a pending
+        row). This is roadmap UX-25, and it is why the list exists.
+      · `email_verified=False` — the confirmation mail hasn't been acted on. Not the admin's to
+        decide, but theirs to help with: on 2026-09-03 the first mail to a fresh Gmail landed in
+        Spam, so "send it again" is a real move.
+    A suspended account is deliberately excluded: it cannot sign in either, but that is a decision
+    already made, not a person stuck waiting on one.
+    """
+    return list(
+        db.execute(
+            select(User)
+            .where(
+                User.is_demo.is_(False),
+                User.is_suspended.is_(False),
+                or_(User.is_active.is_(False), User.email_verified.is_(False)),
+            )
+            .order_by(User.created_at.desc())
+        )
+        .scalars()
+        .all()
+    )
+
+
+@router.get("/pending-access")
+def list_pending_access(_: User = Depends(admin_user), db: Session = Depends(get_db)) -> list[dict]:
+    """The sign-ups that are still outside, with which gate is shut for each. `can_activate` cannot
+    be derived on the client — it needs the invite/allow-list lookup — so it is answered here.
+
+    One `is_allowed` query per row rather than a batched re-implementation of it: the row count is
+    the admin's own backlog of stuck sign-ups (single digits on any real instance), and a second,
+    subtly different copy of the "may this address sign in" rule is exactly the drift this codebase
+    keeps getting bitten by."""
+    out = []
+    for u in _pending_access_rows(db):
+        # The whole rule in one line: this address MAY sign in, and this account still can't. An
+        # undecided request fails it (nothing is allowed yet) and so does a denied one — both belong
+        # to the queue above, which owns that decision. Without this, every fresh registration
+        # appeared in both lists at once, which UAT caught on 2026-09-05.
+        if not is_allowed(db, u.email):
+            continue
+        out.append(_serialize_user(u) | {"can_activate": can_activate(db, u)})
+    return out
+
+
+@router.post("/users/{user_id}/activate")
+def activate_user(
+    user_id: int,
+    admin: User = Depends(admin_user),
+    db: Session = Depends(get_db),
+) -> dict:
+    """Let in a registrant whose address was approved before they signed up (roadmap UX-25).
+
+    Admin-side ONLY, and that is the whole design. Two earlier attempts at this were reverted after
+    review, and both moved authority rather than visibility: auto-activating on registration turns a
+    standing whitelist entry into a bearer grant for whoever registers the address first, and
+    reopening the approved invite to `pending` lets an anonymous sign-up REVOKE a standing approval.
+    This endpoint changes nothing about what an unauthenticated caller can cause — the admin could
+    already do exactly this by re-entering the address in the whitelist box (`add_invite` →
+    `_activate_user_by_email`). What was missing was any way to know they had to."""
+    target = get_or_404(db, User, user_id, detail="No such user")
+    if target.is_demo:
+        raise HTTPException(status_code=400, detail="The demo account can't be activated.")
+    if target.is_active:
+        return _serialize_user(target)  # idempotent: a double click is not an error
+    if not is_allowed(db, target.email):
+        raise HTTPException(
+            status_code=409,
+            detail={"code": "activate", "reason": "not_allowed", "email": target.email},
+        )
+    audit.record(
+        db,
+        admin.id,
+        AuditAction.USER_ACTIVATE,
+        target_type="user",
+        target_id=target.id,
+        summary=target.email,
+        before={"is_active": False},
+        after={"is_active": True},
+    )
+    target.is_active = True
+    db.commit()
+    return _serialize_user(target)
+
+
+@router.post("/users/{user_id}/resend-verification")
+def resend_user_verification(
+    user_id: int,
+    admin: User = Depends(admin_user),
+    db: Session = Depends(get_db),
+) -> dict:
+    """Re-send an account's confirmation link from the admin side.
+
+    The public /auth/verify/resend answers uniformly and reveals nothing, which is right for an
+    anonymous caller but leaves the admin unable to tell a delivered mail from a dropped one. Here
+    the caller is already authenticated as an admin, so this one says plainly what happened.
+
+    Not rate-limited: an admin is not a threat model to enumerate against, and the deliberate silence
+    of the public endpoint is exactly what this exists to escape."""
+    target = get_or_404(db, User, user_id, detail="No such user")
+    if target.is_demo or target.email_verified:
+        raise HTTPException(
+            status_code=409,
+            detail={"code": "resend", "reason": "not_applicable", "email": target.email},
+        )
+    if not email_mod.email_enabled(db):
+        # Mail is fail-soft everywhere else, which is what left the 0.78.5 sign-ups with nothing to
+        # fall back on. An admin pressing a button deserves the failure, not a success toast.
+        raise HTTPException(status_code=409, detail={"code": "resend", "reason": "email_off"})
+    if not send_verification_link(db, target):
+        # Same rule as the invitation above: a button an admin pressed must not answer with a
+        # success for a mail that was dropped. Mail is fail-soft everywhere else because nobody is
+        # waiting on the answer; here somebody is.
+        raise HTTPException(status_code=422, detail={"code": "resend", "reason": "send_failed"})
+    audit.record(
+        db,
+        admin.id,
+        AuditAction.USER_VERIFY_RESEND,
+        target_type="user",
+        target_id=target.id,
+        summary=target.email,
+    )
+    db.commit()
+    return {"ok": True, "email": target.email}
+
+
 def _serialize_demo(row: DemoWhitelist) -> dict:
     return {
         "id": row.id,

backend/app/routes/auth.py

@@ -6,6 +6,8 @@ helpers) stays in app/auth.py, imported below."""
 import ipaddress
 import secrets
 from datetime import datetime, timedelta, timezone
+from typing import NamedTuple
+from urllib.parse import urlencode
 
 from authlib.integrations.starlette_client import OAuth, OAuthError
 from fastapi import APIRouter, BackgroundTasks, Depends, HTTPException, Request
@@ -16,6 +18,7 @@ from sqlalchemy.exc import IntegrityError
 from sqlalchemy.orm import Session
 
 from app import email as email_mod
+from app import mailtext
 from app import sysconfig
 from app.auth import (
     _YOUTUBE_SCOPES,
@@ -25,6 +28,8 @@ from app.auth import (
     READ_SCOPES,
     WRITE_SCOPES,
     current_user,
+    env_admin_canonicals,
+    find_user_by_email,
     get_or_create_demo_user,
     google_enabled,
     is_allowed,
@@ -37,9 +42,15 @@ from app.db import SessionLocal, get_db
 from app.models import AuthToken, DemoWhitelist, Invite, OAuthToken, User
 from app.ratelimit import RateLimiter
 from app.security import encrypt, hash_password, hash_token, verify_password
-from app.utils import valid_email
+from app.utils import canonical_email, valid_email
 
 VERIFY_TTL = timedelta(hours=24)
+# A confirmation link that rides an APPROVAL or an invitation lives longer than one the person is
+# waiting for. Nobody sits refreshing their inbox for an approval — it can easily be read on Monday
+# after a weekend, and if it has expired by then the one-mail-one-click promise is spent and they are
+# back to two messages. The risk is small: this token only ever confirms an address. It signs nobody
+# in and sets no password.
+APPROVAL_VERIFY_TTL = timedelta(days=7)
 RESET_TTL = timedelta(hours=1)
 
 _DECOY_PASSWORD_HASH = hash_password(secrets.token_urlsafe(16))
@@ -47,17 +58,27 @@ _DECOY_PASSWORD_HASH = hash_password(secrets.token_urlsafe(16))
 _register_limiter = RateLimiter(max_events=5, window_seconds=300)
 _login_limiter = RateLimiter(max_events=10, window_seconds=300)
 _reset_limiter = RateLimiter(max_events=5, window_seconds=300)
+# Separate from _reset_limiter on purpose: opening a link must not eat the budget for REQUESTING one.
+_reset_check_limiter = RateLimiter(max_events=10, window_seconds=300)
 _verify_resend_limiter = RateLimiter(max_events=5, window_seconds=300)
 _request_access_limiter = RateLimiter(max_events=5, window_seconds=300)
 _suspend_email_limiter = RateLimiter(max_events=1, window_seconds=3600)
 
 
-def _notify_suspended(background: BackgroundTasks, email: str) -> None:
+def _notify_suspended(background: BackgroundTasks, user: User) -> None:
     """Schedule the one-per-hour 'account suspended' email to a user whose (otherwise valid)
     sign-in was just blocked. Gated by verified credentials at the call site, so this can't be
-    triggered by someone who doesn't control the account."""
-    if _suspend_email_limiter.allow(email):
-        background.add_task(email_mod.send_account_suspended, email, operator_contact())
+    triggered by someone who doesn't control the account.
+
+    Takes the user rather than the address because the mail needs their language, and the send runs
+    as a background task — after this request's session, and the row, are out of reach."""
+    if _suspend_email_limiter.allow(user.email):
+        background.add_task(
+            email_mod.send_account_suspended,
+            user.email,
+            mailtext.lang_for_user(user),
+            operator_contact(),
+        )
 
 
 _demo_limiter = RateLimiter(max_events=5, window_seconds=60)
@@ -90,18 +111,43 @@ def google_oauth(db: Session):
     return _oauth.google
 
 
-def admin_notify_emails(db: Session) -> list[str]:
-    """Who to email about admin events (e.g. a new access request). The ACTUAL admins — every active,
-    non-suspended `role=admin` user — UNIONED with the env ADMIN_EMAILS bootstrap list. Using the DB
-    roles means an admin promoted through the UI is notified too (env alone would miss them, yet they
-    CAN approve requests — the approve UI is role-gated, so the notify set must match); the env union
-    keeps a freshly-seeded instance working before any DB admin exists."""
-    db_admins = db.execute(
-        select(User.email).where(
+def admin_notify_groups(db: Session) -> dict[str, list[str]]:
+    """Who to email about admin events (e.g. a new access request), grouped by the language each of
+    them reads. The ACTUAL admins — every active, non-suspended `role=admin` user — UNIONED with the
+    env ADMIN_EMAILS bootstrap list. Using the DB roles means an admin promoted through the UI is
+    notified too (env alone would miss them, yet they CAN approve requests — the approve UI is
+    role-gated, so the notify set must match); the env union keeps a freshly-seeded instance working
+    before any DB admin exists.
+
+    Grouped rather than one blast to everyone, because these recipients are people with their own UI
+    language: a single message would have to pick one of them and be wrong for the rest. An env
+    address with no admin account still gets looked up, so an operator listed in ADMIN_EMAILS whose
+    account is (say) suspended is still written to in the language they chose."""
+    rows = db.execute(
+        select(User.email, User.preferences).where(
             User.role == "admin", User.is_active.is_(True), User.is_suspended.is_(False)
         )
-    ).scalars()
-    return sorted({e.lower() for e in db_admins if e} | settings.admin_email_set)
+    ).all()
+    by_email = {e.lower(): mailtext.normalize((p or {}).get("language")) for e, p in rows if e}
+    for email in settings.admin_email_set:
+        if email not in by_email:
+            by_email[email] = mailtext.lang_for_email(db, email)
+    groups: dict[str, list[str]] = {}
+    for email in sorted(by_email):
+        groups.setdefault(by_email[email], []).append(email)
+    return groups
+
+
+def notify_admins_of_request(
+    db: Session, background: BackgroundTasks | None, requester: str
+) -> None:
+    """Tell every admin that someone is waiting — one mail per language group. Sends inline when
+    there is no BackgroundTasks to hand (the registration path already runs outside a response)."""
+    for lang, recipients in admin_notify_groups(db).items():
+        if background is None:
+            email_mod.send_admin_new_request(recipients, lang, requester)
+        else:
+            background.add_task(email_mod.send_admin_new_request, recipients, lang, requester)
 
 
 def is_demo_allowed(db: Session, email: str) -> bool:
@@ -147,14 +193,64 @@ def _client_ip(request: Request) -> str:
     return peer
 
 
-def upsert_pending_invite(db: Session, email: str) -> Invite | None:
-    """Idempotently record an access request. Returns the Invite if a *new* pending row
-    was created (so the caller can notify admins), else None for already-known emails."""
+class InviteRequest(NamedTuple):
+    """What an access request settled on.
+
+    `invite` is the row the request now lives under — which is NOT always the address that was just
+    typed: one Gmail mailbox spelled two ways settles on whichever row already exists, and that row's
+    address is where mail will go. Callers that tell the user what happened need it (E9.5 S4).
+    `is_new` is the old boolean return in a name: true only when a row was created or a denied one
+    reopened, i.e. exactly when admins should hear about it. A repeat request must not re-spam them.
+    """
+
+    invite: Invite | None
+    is_new: bool
+
+
+def upsert_pending_invite(db: Session, email: str, lang: str | None = None) -> InviteRequest:
+    """Idempotently record an access request, and the language it was made in.
+
+    "Already known" is decided on the CANONICAL form: `npeter83.temu@` and `npeter83temu@` are one
+    Gmail mailbox, and treating them as two is what put a second, silent access request in the admin
+    queue on 2026-09-03 for an already-approved user. An approved sibling wins — re-requesting must
+    not reopen a decision that has already been made for that mailbox. The row is still STORED under
+    the address as typed, because that is where mail has to go.
+
+    `lang` is the language of the surface the request came from — the sign-in page, or the locale
+    Google reported for a refused sign-in. The latest one wins: someone who asks again from a
+    Hungarian page is telling us something newer than last time. Anything unsupported is ignored
+    rather than stored, so a forged body cannot put junk in the column.
+
+    The commit contract is unchanged: this still commits ONLY when it writes something. Callers rely
+    on that — `_register_account` persists its own flushed user precisely because a no-op here
+    commits nothing (E9.5 S6).
+    """
     email = (email or "").lower()
     if not valid_email(email):
-        return None
-    inv = db.execute(select(Invite).where(Invite.email == email)).scalar_one_or_none()
+        return InviteRequest(None, False)
+    lang = lang if lang in mailtext.SUPPORTED else None
+    canon = canonical_email(email)
+    rows = (
+        db.execute(select(Invite).where(Invite.email_canonical == canon).order_by(Invite.id))
+        .scalars()
+        .all()
+    )
+    # An approved row wins, so a denied duplicate can't mask an approval. Then a row that is not
+    # DENIED, preferring the exact spelling — a denied sibling must never be picked while a pending
+    # row exists, or the reopen branch below would fire and put one person in the admin's queue
+    # twice. Only when every row is denied does the spelling decide which one reopens.
+    undecided = [r for r in rows if r.status != "denied"]
+    inv = (
+        next((r for r in rows if r.status == "approved"), None)
+        or next((r for r in undecided if r.email == email), None)
+        or next(iter(undecided), None)
+        or next((r for r in rows if r.email == email), None)
+        or next(iter(rows), None)
+    )
     if inv is not None:
+        relearned = lang is not None and inv.lang != lang
+        if relearned:
+            inv.lang = lang
         # Let a previously-denied person ask again; don't disturb approved/pending rows.
         if inv.status == "denied":
             inv.status = "pending"
@@ -162,12 +258,39 @@ def upsert_pending_invite(db: Session, email: str) -> Invite | None:
             inv.decided_at = None
             inv.decided_by = None
             db.commit()
-            return inv
-        return None
-    inv = Invite(email=email, status="pending")
+            return InviteRequest(inv, True)
+        if relearned:
+            db.commit()
+        return InviteRequest(inv, False)
+    inv = Invite(email=email, status="pending", lang=lang)
     db.add(inv)
     db.commit()
-    return inv
+    return InviteRequest(inv, True)
+
+
+def _access_notice_url(kind: str, email: str = "", inv: Invite | None = None) -> str:
+    """The landing URL for a Google sign-in that did not reach an account: `requested` (we recorded
+    the request) or `denied` (nothing to record).
+
+    It rides the FRAGMENT, not the query string, for the same reason the verify/reset tokens do
+    (SB3): a fragment never reaches the server, a proxy access log or a Referer header — and this
+    notice now carries the user's address. Naming it is the point of E9.5 S4: on 2026-09-03 a
+    registration as `npeter83.temu@` met an OAuth claim of `npeter83temu@`, and a screen that said
+    "request recorded" without saying FOR WHAT hid the mismatch for a day.
+
+    `linked` names the address the request actually lives under, and ONLY when that differs from the
+    one Google just returned — the honest version of "we didn't open a second request". Same
+    spelling twice is just a repeat, and saying anything there would be noise.
+
+    urlencode (not an f-string): a `+tag` address must arrive as %2B, or the SPA's URLSearchParams
+    would read it back as a space and mangle exactly the address this epic exists to protect.
+    """
+    params = {"access": kind}
+    if email:
+        params["email"] = email
+    if inv is not None and inv.email != email:
+        params["linked"] = inv.email
+    return "/#" + urlencode(params)
 
 
 _DEV_OAUTH_HOSTS = frozenset(
@@ -201,6 +324,12 @@ class EmailIn(BaseModel):
 class EmailPasswordIn(BaseModel):
     email: str | None = None
     password: str | None = None
+    # The language the sign-up page was in. Captured at registration because it is the ONLY moment
+    # the choice exists anywhere the server can see: it lives in the browser until an account does,
+    # and a preference nobody recorded cannot be backfilled later (the lesson `google_email` taught
+    # in E9.5 S3 — those rows still read NULL until each user signs in again). Nothing reads it yet;
+    # the bilingual mail templates are E9.5 S7.
+    lang: str | None = None
 
 
 class TokenIn(BaseModel):
@@ -283,26 +412,37 @@ async def callback(
         # A denied Google login doubles as an access request: record it for the admin and
         # land the user on a friendly "request received" screen instead of a raw 403.
         if email:
-            inv = upsert_pending_invite(db, email)
-            admins = admin_notify_emails(db)
-            if inv is not None and admins:
-                background.add_task(email_mod.send_admin_new_request, admins, email)
-            return RedirectResponse(url="/?access=requested")
-        return RedirectResponse(url="/?access=denied")
+            # Google just told us this person's locale — the only language signal that will ever
+            # exist for an address with no account, and the decision mail is written from it.
+            req = upsert_pending_invite(db, email, (userinfo.get("locale") or "").split("-")[0])
+            if req.is_new:
+                notify_admins_of_request(db, background, email)
+            return RedirectResponse(url=_access_notice_url("requested", email, req.invite))
+        return RedirectResponse(url=_access_notice_url("denied"))
 
     user = db.query(User).filter(User.google_sub == sub).one_or_none()
     if user is None:
-        # No account carries this Google identity yet. If one already exists for this email —
+        # No account carries this Google identity yet. If one already exists for this MAILBOX —
         # e.g. an email+password registration — adopt the Google identity onto it instead of
-        # inserting a duplicate (which would collide on the unique email and 500). Google has
-        # verified the address, so this safely unifies password + Google sign-in on one account.
-        existing = db.query(User).filter(User.email == email).one_or_none()
+        # inserting a duplicate. Google has verified the address, so this safely unifies password +
+        # Google sign-in on one account.
+        #
+        # Matched canonically, and that is not cosmetic: on 2026-09-03 a registration as
+        # `npeter83.temu@gmail.com` met an OAuth claim of `npeter83temu@gmail.com`, the literal
+        # lookup found nothing, and prod ended up with TWO active user rows for one Gmail mailbox
+        # (ids 13 and 14). Exact spelling still wins when both exist, so an account that already
+        # matches literally is never passed over for a canonical sibling.
+        canon = canonical_email(email)
+        candidates = db.query(User).filter(User.email_canonical == canon).order_by(User.id).all()
+        existing = next((u for u in candidates if u.email == email), None) or next(
+            iter(candidates), None
+        )
         if existing is not None:
             if existing.google_sub is not None and existing.google_sub != sub:
                 # A different Google identity is already bound to this email — refuse rather than
                 # hijack it. (Near-impossible with real Google accounts: email↔sub is stable.)
                 log.warning("Google login email collision (different sub): %s", email)
-                return RedirectResponse(url="/?access=denied")
+                return RedirectResponse(url=_access_notice_url("denied"))
             if not userinfo.get("email_verified", False):
                 # Adopting (and activating) a pre-existing password account requires Google to
                 # actually attest the address — otherwise an unverified Google email that merely
@@ -311,7 +451,7 @@ async def callback(
                     "Google login: unverified email, refusing to adopt account: %s",
                     email,
                 )
-                return RedirectResponse(url="/?access=denied")
+                return RedirectResponse(url=_access_notice_url("denied"))
             user = existing
             user.google_sub = sub
             # SEC-10: drop any password pre-set on this account while its email was still unverified,
@@ -328,22 +468,23 @@ async def callback(
     # tell the (verified) owner why — a successful Google auth proves they control this account.
     if user.is_suspended:
         log.info("Suspended account blocked at Google login: %s", email)
-        _notify_suspended(background, user.email)
+        _notify_suspended(background, user)
         return RedirectResponse(url="/?login=suspended")
-    # Keep the email in sync with Google, but never overwrite it with one another account already
-    # owns — that would hit the unique constraint and 500, wedging this user's sign-in (rare: a
-    # Google-side email change to a value that collides with a different local account).
-    if user.email != email:
-        clash = db.query(User).filter(User.email == email, User.id != user.id).one_or_none()
-        if clash is None:
-            user.email = email
+    # Record what Google actually answers with, beside the address the user registered with. The two
+    # are the same string for most people; where they differ (a deliberate `+tag`, a different dot
+    # pattern) the UI shows both, so nobody has to guess which one signs them in.
+    if email:
+        user.google_email = email
+    _sync_google_email(db, user, email)
     user.display_name = userinfo.get("name")
     user.avatar_url = userinfo.get("picture")
     # ADMIN_EMAILS (env) is the bootstrap admin list and always wins, so the configured admin can't
     # be locked out. Everyone else's role is managed in the admin UI and stored in the DB, so a
     # routine login must NOT reset it (that would clobber a UI promotion/demotion). Only seed a
     # default for a brand-new account (its role attribute is still unset before flush).
-    if email in settings.admin_email_set:
+    # Canonical, like every other read of the env lists: a dotted or `+tag`ged ADMIN_EMAILS entry
+    # would otherwise never bootstrap its admin, because Google answers with the plain primary.
+    if canonical_email(email) in env_admin_canonicals():
         user.role = "admin"
     elif not user.role:
         user.role = "user"
@@ -355,8 +496,7 @@ async def callback(
     # picked one yet); unsupported locales fall back to English.
     prefs = dict(user.preferences or {})
     if not prefs.get("language"):
-        loc = (userinfo.get("locale") or "").split("-")[0].lower()
-        prefs["language"] = loc if loc in {"en", "hu"} else "en"
+        prefs["language"] = mailtext.normalize((userinfo.get("locale") or "").split("-")[0].lower())
         user.preferences = prefs
     db.flush()
 
@@ -375,6 +515,30 @@ async def callback(
     return RedirectResponse(url="/")
 
 
+def _sync_google_email(db: Session, user: User, email: str) -> None:
+    """Follow a genuine Google-side email change — and ONLY that.
+
+    A different SPELLING of the same mailbox is the user's own choice and must survive. People
+    register as `me+siftlode@gmail.com` precisely so a later leak from this site is identifiable, and
+    silently rewriting that to `me@gmail.com` destroys the thing it was for. It also locked them out
+    of the spelling they chose, because sign-in matches the stored address first. Google returns the
+    account's PRIMARY address, which need not be what they registered with — and can never contain a
+    `+` at all — so without this guard every plus-tagged registration lost its tag on the first Google
+    sign-in. (E9.5 S3 made that reachable by matching adoption across spellings; the rewrite itself is
+    older.)
+
+    Never overwrite with an address another account already owns either: that would hit the unique
+    constraint and 500, wedging this user's sign-in.
+    """
+    if not email or user.email == email:
+        return
+    if canonical_email(user.email) == canonical_email(email):
+        return  # same mailbox, their spelling — leave it alone
+    clash = db.query(User).filter(User.email == email, User.id != user.id).one_or_none()
+    if clash is None:
+        user.email = email
+
+
 def _store_token(db: Session, user: User, token: dict) -> None:
     """Persist the OAuth grant on the user's single token row, creating it if absent. Google
     only returns a refresh_token on (re)consent, so the previous one is kept otherwise.
@@ -435,6 +599,9 @@ def _complete_link(
     if user.google_sub is not None and user.google_sub != sub:
         return RedirectResponse(url="/?link=mismatch")
     user.google_sub = sub
+    linked_email = (userinfo.get("email") or "").strip().lower()
+    if linked_email:
+        user.google_email = linked_email  # see the sign-in callback: the other half of the identity
     if not user.display_name:
         user.display_name = userinfo.get("name")
     if not user.avatar_url:
@@ -468,15 +635,23 @@ async def logout(request: Request):
     return JSONResponse({"ok": True, "switched": False})
 
 
+class AccessRequestIn(EmailIn):
+    # The language of the page this request was made from. Same reasoning as registration's `lang`
+    # (and the same shape): it is the ONLY moment this preference exists anywhere the server can
+    # see, since the requester has no account to carry it, and it decides what language the approval
+    # or denial mail is written in.
+    lang: str | None = None
+
+
 @router.post("/request-access")
 async def request_access(
-    body: EmailIn,
+    body: AccessRequestIn,
     request: Request,
     background: BackgroundTasks,
     db: Session = Depends(get_db),
 ) -> dict:
     """Public: ask for access. Idempotent — repeat requests for the same email don't
-    duplicate or re-spam admins (upsert returns None for an already-pending row).
+    duplicate or re-spam admins (upsert answers `is_new=False` for an already-pending row).
 
     Answers a uniform ``"pending"`` for EVERY outcome — already-allowed, newly-pending,
     already-pending, and rate-limited alike. The old ``"approved"`` reply for an allow-listed
@@ -491,10 +666,9 @@ async def request_access(
         return {"status": "pending"}
     if is_allowed(db, email):
         return {"status": "pending"}  # already allowed — don't reveal it
-    inv = upsert_pending_invite(db, email)
-    admins = admin_notify_emails(db)
-    if inv is not None and admins:
-        background.add_task(email_mod.send_admin_new_request, admins, email)
+    req = upsert_pending_invite(db, email, body.lang)
+    if req.is_new:
+        notify_admins_of_request(db, background, email)
     return {"status": "pending"}
 
 
@@ -551,6 +725,29 @@ def _issue_token(db: Session, user: User, kind: str, ttl: timedelta) -> str:
     return raw
 
 
+def _peek_token(db: Session, raw: str | None, kind: str) -> User | None:
+    """Is this token still usable — WITHOUT spending it. Same four conditions as _consume_token, and
+    the same "does its user still exist" answer, so the two can never disagree about a given token.
+
+    Deliberately NOT the read half of a read-check-write: _consume_token stays one atomic UPDATE, and
+    this never feeds it. A peek is only ever an early warning — the confirm endpoint remains the
+    authority, because a token can expire, be spent, or lose its account between the two calls.
+    """
+    if not raw:
+        return None
+    row = db.execute(
+        select(AuthToken).where(
+            AuthToken.token_hash == hash_token(raw),
+            AuthToken.kind == kind,
+            AuthToken.used_at.is_(None),
+            AuthToken.expires_at >= datetime.now(timezone.utc),
+        )
+    ).scalar_one_or_none()
+    # db.get, exactly as _consume_token does: a deleted account cascades its tokens away, so this is
+    # belt-and-braces — but the two must agree, and agreeing by construction beats agreeing by luck.
+    return db.get(User, row.user_id) if row is not None else None
+
+
 def _consume_token(db: Session, raw: str | None, kind: str) -> User | None:
     """Validate + burn a token atomically. Returns its user, or None if missing/expired/used/wrong
     kind. The burn is a single conditional UPDATE (…WHERE used_at IS NULL…RETURNING) rather than a
@@ -606,17 +803,59 @@ def register(
     # session). The create path hashes the password + writes several rows + schedules emails; doing it
     # inline would make a NEW email respond measurably slower than an already-registered one (which
     # skips all that) — a timing oracle for enumeration. Off-path, any valid email responds the same.
-    background.add_task(_register_account, email, password)
+    background.add_task(_register_account, email, password, body.lang)
     return {"status": "ok"}
 
 
-def _register_account(email: str, password: str) -> None:
+def _register_account(email: str, password: str, lang: str | None = None) -> None:
     """Background worker for /register: create the pending account (+ verification email + admin
     notice) for a genuinely new email; no-op for an already-registered one. Runs after the response
     with its own DB session, so the request's timing never reveals whether the email already exists."""
     with SessionLocal() as db:
-        if db.execute(select(User).where(User.email == email)).scalar_one_or_none() is not None:
-            return  # already registered — nothing to do (the uniform "ok" was already returned)
+        # Canonical, so a second spelling of one Gmail mailbox cannot open a SECOND account. Prod
+        # already carries such a pair (user ids 13 and 14, both for npeter83temu@gmail.com); this is
+        # the end that stops new ones appearing, while the Google callback copes with the existing.
+        candidates = (
+            db.execute(
+                select(User).where(User.email_canonical == canonical_email(email)).order_by(User.id)
+            )
+            .scalars()
+            .all()
+        )
+        # Exact spelling wins when a mailbox carries two rows, same as every other canonical lookup
+        # in this epic (`find_user_by_email`, `_activate_user_by_email`, the Google callback). Without
+        # it `.first()` handed back whichever row Postgres felt like, so a re-registration of the
+        # dotted spelling could resolve to the undotted, already-confirmed twin and send nothing.
+        existing = next((u for u in candidates if u.email == email), None) or next(
+            iter(candidates), None
+        )
+        if existing is not None:
+            # Already registered. This used to return in silence, and that silence is the most
+            # likely explanation for the 2026-09-03 report that a confirmation mail "never arrived":
+            # nothing was ever SENT. The person re-registered, got the same cheerful "check your
+            # inbox", and waited for a message that did not exist.
+            #
+            # Re-sending the link instead leaks nothing new. The response and its timing are
+            # unchanged (uniform "ok", decided off the response path), the mail goes to the address
+            # ON THE ACCOUNT, and this is exactly what the public /auth/verify/resend already does
+            # for the same input — so it is not a new capability, just the end of a dead end. An
+            # account that is already confirmed still gets nothing: there is nothing to confirm.
+            #
+            # And a re-send is ALL it does: the submitted password is discarded. E9.5's closing
+            # review tried "while the address is unverified, the newest registration owns it"
+            # (replace the hash, kill the outstanding verify tokens) as a fix for address
+            # pre-emption, and round 2 showed it was worse than the problem — DO NOT REPEAT IT.
+            # The rule is symmetric, and an attacker can always be last: it hands an unauthenticated
+            # caller the power to overwrite a real registrant's chosen password and delete the
+            # confirmation link already in their inbox, and on a SEC-10-stripped row (password_hash
+            # NULL, password_revoked_at set) it would install a password where the whole point was
+            # that there is none. The owner's real recourse already exists and needs no new
+            # primitive: password-reset accepts this account, proves the mailbox, rewrites the hash
+            # and bumps the session epoch. The residual is logged as SEC-16.
+            user = existing
+            if not user.email_verified and not user.is_demo and email_mod.email_enabled():
+                send_verification_link(db, user)
+            return
         # Without working SMTP we can't deliver a verification link, so email ownership can't gate
         # sign-in. Admin approval stays the real gate (is_active=False); mark the account verified so
         # the flow still completes on a no-SMTP self-host. See email.email_enabled().
@@ -626,6 +865,8 @@ def _register_account(email: str, password: str) -> None:
             password_hash=hash_password(password),
             is_active=False,
             email_verified=not email_ok,
+            # Only a supported code is stored, so a forged body can't put junk in preferences.
+            preferences={"language": lang} if lang in mailtext.SUPPORTED else {},
         )
         db.add(user)
         try:
@@ -636,28 +877,81 @@ def _register_account(email: str, password: str) -> None:
             # no-op as the pre-check hit — roll back and stop.
             db.rollback()
             return
-        upsert_pending_invite(db, email)  # admin-approval gate (commits)
+        upsert_pending_invite(db, email)  # admin-approval gate
+        # Persist the account ourselves. upsert_pending_invite commits only when it actually writes an
+        # invite row — not when this address already has a pending or approved one — and _issue_token
+        # below only runs with SMTP on. So for an address the admin had already approved (or one whose
+        # request was still pending), on an instance with no working SMTP, NOTHING along this path
+        # committed and the flushed user was silently rolled back when the session closed: the
+        # would-be user got the uniform "ok" and no account, and re-registering did the same again.
+        # Commit unconditionally; it is a no-op when upsert already committed the same transaction.
+        db.commit()
         if email_ok:
-            raw = _issue_token(db, user, "verify", VERIFY_TTL)
-            # Fragment (#), not a query token: keeps the token out of proxy/access logs + Referer (SB3).
-            email_mod.send_verify_email(email, f"{_app_base()}/#verify={raw}")
-        admins = admin_notify_emails(db)
-        if admins:
-            email_mod.send_admin_new_request(admins, email)
+            send_verification_link(db, user)
+        # Fired unconditionally, unlike the other two callers which gate on a fresh invite row: for
+        # an address the admin already approved, nothing lands in the Access-requests queue, so this
+        # is the only place the account's existence is announced at all. Delivery is a separate
+        # matter — with no working SMTP `_send` drops it, which is why the pre-approved registrant
+        # still needs the admin to notice them (roadmap UX-25).
+        notify_admins_of_request(db, None, email)
+
+
+def issue_verification_link(db: Session, user: User, ttl: timedelta | None = None) -> str:
+    """A fresh confirmation link for `user`, returned rather than sent — for a mail that carries the
+    link inside a larger message (the branching approval/invitation mails, E9.5 S6).
+
+    Same token machinery and the same fragment (SB3) as the standalone confirmation mail, so the two
+    kinds of link cannot drift apart in shape or in how they are consumed."""
+    raw = _issue_token(db, user, "verify", ttl or VERIFY_TTL)
+    return f"{_app_base()}/#verify={raw}"
+
+
+def send_verification_link(db: Session, user: User) -> bool:
+    """Issue a fresh verification token for `user` and mail them the link.
+
+    Always to the address ON THE ACCOUNT, never a spelling typed into some form: the account's
+    address is the one its owner chose to be reachable at, and a `+tag` there is usually deliberate.
+    The token rides the URL FRAGMENT (#) so it can never reach a proxy/access log or a Referer (SB3).
+
+    One definition, three callers — registration, the self-service resend, and the admin-side resend
+    (E9.5 S5). The link's shape and TTL must not drift between them; a verification mail that differs
+    by who triggered it is a bug waiting to be discovered by exactly one user.
+
+    Returns whether the mail actually went out, so a caller with a human waiting on the answer (the
+    admin-side resend) can say so instead of reporting success for a message that was dropped.
+    """
+    return email_mod.send_verify_email(
+        user.email,
+        mailtext.lang_for_user(user),
+        issue_verification_link(db, user),
+        hours=int(VERIFY_TTL.total_seconds() // 3600),
+    )
 
 
 @router.post("/verify")
 def verify_email_confirm(body: TokenIn, db: Session = Depends(get_db)) -> dict:
     """Confirm an email-verification token the SPA read from the URL fragment (SB3). Uniform 400
-    on any invalid/expired/used token."""
+    on any invalid/expired/used token.
+
+    `password_reset_required` tells the SPA to send the user straight to the reset flow: SEC-10 had
+    dropped the password this account registered with, so sign-in would answer with the deliberately
+    uniform "Invalid email or password" — true, but unreadable to the person who just proved they own
+    the mailbox. Saying so leaks nothing: holding a valid single-use verify token for this account
+    already proves that much. Since E9.5 S1 the common source of that state is gone (admin approval no
+    longer revokes), leaving accounts stripped before that change and the Google-adoption path, so this
+    flag is rare now — but it must stay, because those users have no other way back in."""
     user = _consume_token(db, body.token, "verify")
     if user is None:
-        raise HTTPException(
-            status_code=400, detail="This verification link is invalid or has expired."
-        )
+        raise HTTPException(status_code=400, detail={"code": "verify", "reason": "invalid"})
     user.email_verified = True
+    needs_password = user.password_hash is None and user.password_revoked_at is not None
+    email = user.email
     db.commit()
-    return {"ok": True}
+    # Naming the address lets the SPA say WHICH mailbox it just confirmed — the same reasoning as
+    # password_reset_required above: holding a valid single-use verify token for this account already
+    # proves that much, so echoing it back leaks nothing. It matters in a browser that holds a session
+    # for a different account, where an unqualified "email confirmed" would be actively misleading.
+    return {"ok": True, "password_reset_required": needs_password, "email": email}
 
 
 @router.post("/verify/resend")
@@ -687,22 +981,36 @@ def _resend_verify_if_eligible(email: str) -> None:
     if not email_mod.email_enabled():
         return
     with SessionLocal() as db:
-        user = db.execute(select(User).where(User.email == email)).scalar_one_or_none()
+        user = find_user_by_email(db, email)
         if user is not None and not user.email_verified and not user.is_demo:
-            raw = _issue_token(db, user, "verify", VERIFY_TTL)
-            email_mod.send_verify_email(email, f"{_app_base()}/#verify={raw}")
+            send_verification_link(db, user)
 
 
-@router.get("/verify")
-def verify_email(token: str, db: Session = Depends(get_db)):
-    """Legacy query-token verification link (pre-SB3 emails still in flight). New emails use the
-    fragment + POST flow above; this bounces to a friendly status for older links until they expire."""
-    user = _consume_token(db, token, "verify")
-    if user is None:
-        return RedirectResponse(url="/?verify=invalid")
-    user.email_verified = True
-    db.commit()
-    return RedirectResponse(url="/?verify=ok")
+def _login_refused(status: int, reason: str, user: User | None = None, **extra) -> HTTPException:
+    """Every refusal password_login can answer with, in the codebase's structured `{code, reason}`
+    shape so the SPA can say it in the user's own language (the old bare English strings were
+    unreadable under a bilingual UI, and unusable as anything but a one-line error).
+
+    The account-shaped reasons carry the address ON THE ACCOUNT plus both gate flags. That is what
+    turns a flat 403 into an honest screen — it names the mailbox and says which of the two gates is
+    still shut. It is not an enumeration leak: this branch is only reachable once the password has
+    been proven, so the caller already knows the account exists. The two reasons that answer BEFORE
+    that proof (`invalid`, `rate_limited`) carry nothing at all, so they stay byte-identical for a
+    real account and an unknown one.
+
+    Since E9.5 S1 the two gates are order-independent, so `approved` really can be true while
+    `email_verified` is false, and vice versa — the SPA renders whichever is actually outstanding
+    rather than assuming a sequence.
+    """
+    detail: dict = {"code": "login", "reason": reason}
+    if user is not None:
+        detail |= {
+            "email": user.email,
+            "email_verified": user.email_verified,
+            "approved": user.is_active,
+        }
+    detail |= {k: v for k, v in extra.items() if v is not None}
+    return HTTPException(status_code=status, detail=detail)
 
 
 @router.post("/password-login")
@@ -716,29 +1024,23 @@ def password_login(
     Once the password is proven correct, the owner gets a specific reason if their account is
     still pending or suspended — that's not an enumeration leak (they already hold the password)."""
     if not _login_limiter.allow(_client_ip(request)):
-        raise HTTPException(status_code=429, detail="Too many attempts. Try again shortly.")
+        raise _login_refused(429, "rate_limited")
     email = (body.email or "").strip().lower()
     password = body.password or ""
-    user = db.execute(select(User).where(User.email == email)).scalar_one_or_none()
+    user = find_user_by_email(db, email)
     # Always run the KDF (against a decoy hash for an unknown / passwordless / demo account) so the
     # response time is the same whether or not the email exists — no timing-based enumeration.
     candidate_hash = user.password_hash if (user and not user.is_demo) else None
     password_ok = verify_password(password, candidate_hash or _DECOY_PASSWORD_HASH)
     if user is None or user.is_demo or not password_ok:
-        raise HTTPException(status_code=401, detail="Invalid email or password.")
+        raise _login_refused(401, "invalid")
     if user.is_suspended:
-        _notify_suspended(background, user.email)
-        op = operator_contact()
-        detail = "Your account has been suspended."
-        if op:
-            detail += f" If you have questions, contact the operator at {op}."
-        raise HTTPException(status_code=403, detail=detail)
+        _notify_suspended(background, user)
+        raise _login_refused(403, "suspended", user, operator=operator_contact() or None)
     if not user.email_verified:
-        raise HTTPException(
-            status_code=403, detail="Please verify your email first (check your inbox)."
-        )
+        raise _login_refused(403, "email_unverified", user)
     if not user.is_active:
-        raise HTTPException(status_code=403, detail="Your account is awaiting admin approval.")
+        raise _login_refused(403, "pending_approval", user)
     _establish_session(request, user)
     log.info("Password login: %s (id=%s, role=%s)", email, user.id, user.role)
     return {"ok": True}
@@ -767,12 +1069,43 @@ def _send_reset_if_eligible(email: str) -> None:
     """Background worker for password_reset_request: issue a reset token + email the link, but ONLY
     for a real (non-demo) password account. Runs after the response with its own DB session, so the
     request's timing never reveals whether the account exists. Token rides the URL FRAGMENT (#) so it
-    can't leak into proxy/access logs or a Referer (SB3)."""
+    can't leak into proxy/access logs or a Referer (SB3).
+
+    "Password account" is `password_hash OR password_revoked_at` — an account SEC-10 stripped had a
+    password and must be able to get a new one, or it is locked out permanently (no password to sign in
+    with, and formerly no reset link either). A Google-only account that never had a password stays
+    ineligible on purpose: its owner adds one from Settings (/auth/set-password) while signed in, which
+    proves identity through the session rather than by mail."""
     with SessionLocal() as db:
-        user = db.execute(select(User).where(User.email == email)).scalar_one_or_none()
-        if user is not None and user.password_hash and not user.is_demo:
+        user = find_user_by_email(db, email)
+        if user is None or user.is_demo:
+            return
+        if user.password_hash or user.password_revoked_at:
             raw = _issue_token(db, user, "reset", RESET_TTL)
-            email_mod.send_password_reset(email, f"{_app_base()}/#reset={raw}")
+            # The account's own address, as above — never the spelling that was typed into the form.
+            email_mod.send_password_reset(
+                user.email, mailtext.lang_for_user(user), f"{_app_base()}/#reset={raw}"
+            )
+
+
+@router.post("/password-reset/check")
+def password_reset_check(body: TokenIn, request: Request, db: Session = Depends(get_db)) -> dict:
+    """Is the reset link the SPA just opened still good? Answers without spending the token.
+
+    Why this exists: the card used to render "set a new password" purely because a `#reset=` fragment
+    was present, never asking whether it could still succeed. Reported on 2026-09-05 after deleting an
+    account and then opening its reset link — the user types a new password into a form that answers
+    400. Opening a dead reset link is not an edge case: the token lives one hour, mail is slow or lands
+    in spam, and whoever got two mails usually clicks the older one.
+
+    Not an enumeration oracle: probing requires already holding a 43-character random, and the answer
+    is exactly what submitting it would reveal. Throttled per IP anyway — and a throttled caller is
+    told `true`, never `false`: this check may only ever save a user a wasted form, so when it cannot
+    answer it must degrade to the old behaviour instead of declaring a live link dead.
+    """
+    if not _reset_check_limiter.allow(_client_ip(request)):
+        return {"ok": True}
+    return {"ok": _peek_token(db, body.token, "reset") is not None}
 
 
 @router.post("/password-reset/confirm")
@@ -783,12 +1116,13 @@ def password_reset_confirm(body: TokenPasswordIn, db: Session = Depends(get_db))
     if len(new_password) < PASSWORD_MIN_LEN:
         raise HTTPException(
             status_code=400,
-            detail=f"Password must be at least {PASSWORD_MIN_LEN} characters.",
+            detail={"code": "reset", "reason": "weak_password", "min": PASSWORD_MIN_LEN},
         )
     user = _consume_token(db, token, "reset")
     if user is None:
-        raise HTTPException(status_code=400, detail="This reset link is invalid or has expired.")
+        raise HTTPException(status_code=400, detail={"code": "reset", "reason": "invalid"})
     user.password_hash = hash_password(new_password)
+    user.password_revoked_at = None  # the account has a password again — SEC-10's trace is spent
     # A valid reset link proves control of the mailbox, so completing a reset also verifies the
     # email — this rescues an account that registered but never clicked the verification link (it
     # can then sign in). The separate admin-approval gate (is_active) is deliberately NOT touched
@@ -828,12 +1162,33 @@ def bump_session_epoch(user: User) -> None:
 def revoke_preset_password_if_unverified(user: User) -> None:
     """SEC-10 (account pre-emption): a password set on an account whose email was NEVER verified is
     untrusted — whoever registered the address (to pre-empt the real owner) could have chosen it. When
-    ownership is finally attested (Google adoption, or admin approval), drop that password and bump the
-    epoch to revoke any session it minted; the owner re-sets one via password-reset. No-op for an
-    already-verified account, so a legit no-SMTP registration is unaffected. The single source for this
-    rule — both the Google-callback and admin-activation paths call it so they can't drift."""
+    the real owner attests ownership through Google, drop that password and bump the epoch to revoke any
+    session it minted; the owner re-sets one via password-reset. No-op for an already-verified account,
+    so a legit no-SMTP registration is unaffected.
+
+    The Google-adoption callback is the ONLY caller (E9.5 S1). Admin approval used to call this too, and
+    dropping it was right for the reason S1 gave — the revoke destroyed the password a legitimate
+    registrant had just chosen, and since the admin normally decides before the user reads their mail,
+    that made the "your password was cleared" detour the DEFAULT path rather than an edge case.
+
+    S1 also claimed the revoke was REDUNDANT there, because `password_login` refuses an unverified
+    account before it reads `is_active`. That part was wrong, and the epic's own review caught it: the
+    gate holds only while the address is unverified, and S6's approval mail exists to get the real
+    owner to end that state — at which point a pre-emptor's password works. Nothing replaced the
+    revoke, and that is deliberate. The review tried "the newest registration owns an unverified
+    account" and reverted it: the rule is symmetric, so an attacker can simply register last, and it
+    would have handed anonymous callers a write onto a real account's credential. What the owner
+    actually has is password-reset, which proves the mailbox, rewrites the hash and bumps the epoch.
+    The residual is logged as SEC-16; re-adding a caller here would put "your password was cleared"
+    back in front of every legitimate registrant, which is the whole reason S1 removed it.
+
+    `password_revoked_at` is what makes "the owner re-sets one via password-reset" actually true. The
+    revoke leaves `password_hash IS NULL`, which is also what a Google-only account looks like — and
+    _send_reset_if_eligible keyed off exactly that, so a revoked account silently got no reset link and
+    was locked out for good (it could not sign in either). The stamp separates the two cases."""
     if not user.email_verified:
         user.password_hash = None
+        user.password_revoked_at = datetime.now(timezone.utc)
         bump_session_epoch(user)
 
 
@@ -903,6 +1258,7 @@ def set_password(
         if not verify_password(body.current_password or "", user.password_hash):
             raise HTTPException(status_code=403, detail="Current password is incorrect.")
     user.password_hash = hash_password(new_password)
+    user.password_revoked_at = None  # same as the reset path: a password exists again
     # SA4: a password change logs out every OTHER session; re-stamp this cookie at the new epoch so
     # the person making the change stays signed in here. Commit BEFORE re-stamping so a failed commit
     # can't leave the cookie at a newer epoch than the DB (which would wrongly 401 THIS session).

backend/app/routes/channels.py

@@ -229,6 +229,7 @@ def _channel_detail_dict(
     count_live: int,
     deep_requested: bool,
     priority: int,
+    hidden: bool,
     tag_ids: list[int],
 ) -> dict:
     return {
@@ -262,6 +263,9 @@ def _channel_detail_dict(
         # This user's per-subscription feed priority (0 when not subscribed) so the channel page can
         # offer the same priority stepper as the manager. Editable only while subscribed.
         "priority": priority,
+        # This user's per-subscription "hide from feed" flag (False when not subscribed), so the
+        # channel page can offer the same Unhide toggle the manager has. Editable only while subscribed.
+        "hidden": hidden,
         "backfill_done": channel.backfill_done,
         "from_explore": channel.from_explore,
         "details_synced": channel.details_synced_at is not None,
@@ -344,6 +348,7 @@ def channel_detail(
         count_live=count_live,
         deep_requested=bool(sub.deep_requested) if sub else False,
         priority=int(sub.priority) if sub else 0,
+        hidden=bool(sub.hidden) if sub else False,
         tag_ids=tag_ids,
     )
 

backend/app/routes/config.py

@@ -10,6 +10,7 @@ from sqlalchemy.orm import Session
 
 from app import audit
 from app import email as email_mod
+from app import mailtext
 from app import sysconfig
 from app.audit import AuditAction
 from app.auth import admin_user
@@ -115,7 +116,7 @@ def send_test_email(
     lets the admin verify the settings actually work."""
     if not email_mod.email_enabled():
         raise HTTPException(status_code=400, detail="SMTP is not configured.")
-    sent = email_mod.send_test(user.email)
+    sent = email_mod.send_test(user.email, mailtext.lang_for_user(user))
     if not sent:
         raise HTTPException(status_code=422, detail="SMTP send failed — check the settings.")
     return {"sent": True, "to": user.email}

backend/app/routes/downloads.py

@@ -6,23 +6,28 @@ worker is a separate process); this module never downloads — it enqueues, mana
 serves finished files (range-aware, with the user's custom display name), and shares them.
 """
 
+import os
 import re
+import tempfile
 from datetime import datetime, timedelta, timezone
+from pathlib import Path
 from urllib.parse import parse_qs, urlparse
 
-from fastapi import APIRouter, Depends, HTTPException, Request
+from fastapi import APIRouter, Depends, File, Form, HTTPException, Request, UploadFile
 from fastapi.responses import FileResponse
 from pydantic import BaseModel
 from sqlalchemy import func, select
 from sqlalchemy.orm import Session
 
-from app import sysconfig
+from app import audit, sysconfig
 from app.auth import admin_user, require_human
 from app.config import settings
 from app.db import get_db
+from app.downloads import credentials as dlcreds
 from app.downloads import edit as editmod
 from app.downloads import links as linksmod
 from app.downloads import quota, service, storage
+from app.downloads import upload as uploadmod
 from app.models import (
     DownloadJob,
     DownloadLink,
@@ -122,6 +127,9 @@ def _serialize(job: DownloadJob, asset: MediaAsset | None) -> dict:
             "width": asset.width,
             "height": asset.height,
             "container": asset.container,
+            # "video" | "audio" | "file" — the library gates play/edit on this (media only); a
+            # generic uploaded file is download-only. Null while still in flight (set at finalize).
+            "media_kind": asset.media_kind,
             "uploader_url": asset.uploader_url,
             "thumbnail_url": asset.thumbnail_url,
             "expires_at": iso(asset.expires_at),
@@ -247,6 +255,65 @@ def delete_profile(
     return {"deleted": profile_id}
 
 
+# --- per-user download auth (cookies) ------------------------------------------------------
+# Write-only surface: the stored blob is NEVER returned — only the supported hosts + whether each
+# is configured + when. See downloads.credentials for the host-scope + cache-privacy guarantees.
+
+
+@router.get("/credentials")
+def list_credentials(user: User = Depends(require_human), db: Session = Depends(get_db)) -> dict:
+    return {"hosts": dlcreds.status_list(db, user.id)}
+
+
+class SetCredentialIn(BaseModel):
+    cookies: str
+
+
+@router.put("/credentials/{host_key}")
+def set_credential(
+    host_key: str,
+    body: SetCredentialIn,
+    user: User = Depends(require_human),
+    db: Session = Depends(get_db),
+) -> dict:
+    """Store (encrypted) this user's cookies.txt for one supported host. Write-only: the value is
+    never echoed back, logged, or audited — only the fact that it changed."""
+    if not dlcreds.is_supported_host(host_key):
+        raise HTTPException(status_code=404, detail="Unknown host")
+    try:
+        cleaned = dlcreds.validate_cookies(body.cookies)
+    except dlcreds.InvalidCookies as e:
+        raise HTTPException(status_code=400, detail={"code": "cookies", "reason": str(e)})
+    dlcreds.upsert_credential(db, user.id, host_key, cleaned)
+    audit.record(
+        db,
+        user.id,
+        audit.AuditAction.DOWNLOAD_CREDENTIAL_SET,
+        target_type="download_credential",
+        target_id=host_key,
+    )
+    db.commit()
+    return {"ok": True, "hosts": dlcreds.status_list(db, user.id)}
+
+
+@router.delete("/credentials/{host_key}")
+def delete_credential(
+    host_key: str, user: User = Depends(require_human), db: Session = Depends(get_db)
+) -> dict:
+    if not dlcreds.is_supported_host(host_key):
+        raise HTTPException(status_code=404, detail="Unknown host")
+    if dlcreds.delete_credential(db, user.id, host_key):
+        audit.record(
+            db,
+            user.id,
+            audit.AuditAction.DOWNLOAD_CREDENTIAL_DELETE,
+            target_type="download_credential",
+            target_id=host_key,
+        )
+    db.commit()
+    return {"ok": True, "hosts": dlcreds.status_list(db, user.id)}
+
+
 def _resolve_spec(
     db: Session, user: User, profile_id: int | None, spec: dict | None
 ) -> tuple[dict, int | None]:
@@ -294,6 +361,61 @@ def enqueue_download(
     return _serialize_job(db, job)
 
 
+# Read the upload in 1 MiB chunks so a large file never sits fully in memory, and the size cap is
+# enforced on the ACTUAL bytes read (a client-set Content-Length can't be trusted to gate it).
+_UPLOAD_CHUNK = 1024 * 1024
+
+
+@router.post("/upload")
+def upload_download(
+    file: UploadFile = File(...),
+    display_name: str | None = Form(None),
+    user: User = Depends(require_human),
+    db: Session = Depends(get_db),
+) -> dict:
+    """Ingest a local file into the caller's library (E7 S5). Any file type is accepted; media
+    (video/audio) gets the full function set, a generic file is download-only. The file is streamed
+    to a temp path under the download volume (enforcing the per-file cap as it goes), then handed to
+    the non-yt-dlp ingest which probes + places it and returns an already-`done` job.
+
+    A sync (threadpool) handler on purpose: the ingest does blocking work — an ffprobe of up to 30s
+    plus sync DB writes — so it must NOT run on the event loop. `file.file` is the sync file object
+    Starlette spools the multipart body into."""
+    cap = sysconfig.get_int(db, "download_upload_max_bytes")
+    staging = Path(settings.download_root) / ".staging" / "uploads"
+    staging.mkdir(parents=True, exist_ok=True)
+    fd, tmp = tempfile.mkstemp(dir=str(staging))
+    tmp_path = Path(tmp)
+    try:
+        size = 0
+        with os.fdopen(fd, "wb") as out:
+            while chunk := file.file.read(_UPLOAD_CHUNK):
+                size += len(chunk)
+                if cap and size > cap:
+                    raise HTTPException(
+                        status_code=422, detail={"code": "upload_too_large", "limit": cap}
+                    )
+                out.write(chunk)
+        if size == 0:
+            raise HTTPException(status_code=400, detail={"code": "upload_empty"})
+        try:
+            job = uploadmod.ingest_upload(
+                db,
+                user.id,
+                filename=file.filename or "upload",
+                src_path=tmp_path,
+                size=size,
+                display_name=(display_name or "").strip() or None,
+            )
+        except quota.QuotaExceeded as e:
+            raise HTTPException(status_code=422, detail=_quota_detail(e))
+        return _serialize_job(db, job)
+    finally:
+        # Ingest MOVES the temp file into place on success (unlink is then a no-op); on any early exit
+        # — cap hit, empty, quota, probe/move error — this removes the abandoned staging file.
+        tmp_path.unlink(missing_ok=True)
+
+
 class EnqueueEditIn(BaseModel):
     source_job_id: int = 0
     edit_spec: dict
@@ -484,8 +606,10 @@ def redownload_download(
     never deletes a file another job/user still shares: the old asset is only removed if THIS job
     was its last holder."""
     job = _own_job(db, user, job_id)
-    if job.job_kind == "edit":
-        raise HTTPException(status_code=409, detail="Editor clips can't be re-downloaded.")
+    if job.job_kind in ("edit", "upload"):
+        # Neither has a re-fetchable source: an editor clip is derived locally, an upload IS the
+        # source. Re-running yt-dlp against source_kind='upload'/'edit' would just fail.
+        raise HTTPException(status_code=409, detail="This item can't be re-downloaded.")
     if job.status in ("queued", "running", "paused"):
         raise HTTPException(status_code=409, detail="This download is still in progress.")
     service.redownload(db, job)
@@ -550,8 +674,21 @@ def download_file(
 
     asset.last_access_at = datetime.now(timezone.utc)
     db.commit()
-    # Starlette's FileResponse honours the Range header (206 partial content) for seek/resume.
-    return FileResponse(path, filename=filename)
+    # The served Content-Type comes from the ffprobe-verified media_kind + a container allow-list
+    # (storage.served_media_type), NEVER guessed from the file's own extension. A generic 'file' (and
+    # any media whose container we don't recognise — e.g. a media/HTML polyglot named "evil.html")
+    # returns None → a neutral force-download attachment, so uploaded HTML/SVG can't execute inline on
+    # this origin. Recognised media is served with its real type so the in-app player streams it. Both
+    # are range-aware (FileResponse → 206).
+    media_type = storage.served_media_type(asset.media_kind, asset.container)
+    if media_type is None:
+        return FileResponse(
+            path,
+            filename=filename,
+            media_type="application/octet-stream",
+            content_disposition_type="attachment",
+        )
+    return FileResponse(path, filename=filename, media_type=media_type)
 
 
 # --- editor filmstrip (scrub track) --------------------------------------------------------
@@ -763,7 +900,12 @@ def list_links(
 
 class CreateLinkIn(BaseModel):
     password: str = ""
-    allow_download: bool = False
+    # D1 (E7 S3): a newly shared download is downloadable by default — the common intent is "let the
+    # recipient have the file", not stream-only. Forward-only: this only sets the default for links
+    # minted from now on; existing links keep whatever `allow_download` they were created with (the
+    # column default stays False, so no back-catalogue link silently flips). The owner can still
+    # uncheck it in the Share dialog, and toggle any link stream-only afterwards.
+    allow_download: bool = True
     expires_days: int | None = None
 
 

backend/app/routes/feed.py

@@ -14,6 +14,7 @@ from app.feedquery import (
     decode_cursor,
     encode_cursor,
     feed_summary,
+    feed_years,
     filtered_query,
     keyset_predicate,
     order_by,
@@ -53,6 +54,8 @@ def _feed_params(
     tag_mode_language: str = "or",
     tag_mode_topic: str = "or",
     tag_mode_other: str = "or",
+    # "No tag" filter: keep only channels the user has not personally tagged (no user-owned ChannelTag).
+    untagged: bool = False,
     channel_ids: list[str] = Query(default=[]),
     q: str | None = None,
     min_duration: int | None = None,
@@ -74,6 +77,7 @@ def _feed_params(
             "topic": tag_mode_topic,
             "other": tag_mode_other,
         },
+        "untagged": untagged,
         "channel_ids": channel_ids,
         "q": q,
         "min_duration": min_duration,
@@ -203,6 +207,19 @@ def get_feed_summary(
     return feed_summary(db, user, **params)
 
 
+@router.get("/feed/years")
+def get_feed_years(
+    params: dict = Depends(_feed_params),
+    user: User = Depends(current_user),
+    db: Session = Depends(get_db),
+) -> dict:
+    """Per-year video counts for the year control (item 8 / E8·S2): the quick recent-year chips and the
+    "more…" per-year-counts dialog. Every filter EXCEPT the publish-date narrowing applies, so picking a
+    year re-queries the feed but not this list. Response: {"years": [{"year": <int>, "count": <int>}]},
+    newest year first."""
+    return {"years": feed_years(db, user, **params)}
+
+
 class VideoStateIn(BaseModel):
     status: str
 

backend/app/routes/me.py

@@ -5,6 +5,7 @@ from sqlalchemy.orm import Session
 
 from app.auth import (
     count_admins,
+    count_pending_activations,
     current_user,
     google_enabled,
     has_read_scope,
@@ -13,6 +14,7 @@ from app.auth import (
     optional_current_user,
     purge_user,
 )
+from app import email as email_mod
 from app import sysconfig
 from app.db import get_db
 from app.models import Invite, User
@@ -98,11 +100,21 @@ def get_me(
     if user is None:
         return {"authenticated": False}
     pending_invites = 0
+    pending_activations = 0
+    # Admin-only, because it drives an operator warning: email is fail-soft, so a half-filled SMTP
+    # config costs verification links, password resets and access-request notices with nothing
+    # visible anywhere. Surfacing it here puts the warning on the screens where onboarding happens.
+    email_configured = True
     if user.role == "admin":
         pending_invites = (
             db.scalar(select(func.count()).select_from(Invite).where(Invite.status == "pending"))
             or 0
         )
+        # Counted separately from pending_invites rather than folded into it: the two are different
+        # facts (a request awaiting a decision vs a decided address whose sign-up never got let in),
+        # and quietly widening one number would make an existing field mean something new.
+        pending_activations = count_pending_activations(db)
+        email_configured = email_mod.email_enabled(db)  # this request's session; no second connect
     return {
         "authenticated": True,
         "id": user.id,
@@ -112,6 +124,12 @@ def get_me(
         "role": user.role,
         "is_demo": user.is_demo,
         "has_google": user.google_sub is not None,
+        # The address Google answers with, when it DIFFERS from the account's own. Same string for
+        # most people, and then this is None so no surface has to decide whether to show it — the
+        # comparison lives here, once, instead of in every consumer.
+        "google_email": (
+            user.google_email if user.google_email and user.google_email != user.email else None
+        ),
         "has_password": user.password_hash is not None,
         # Instance-wide: whether Google sign-in / YouTube connect is available at all (the UI hides
         # YouTube-access affordances and the onboarding nudge when it isn't configured).
@@ -121,6 +139,10 @@ def get_me(
         "can_read": has_read_scope(user),
         "can_write": has_write_scope(user),
         "pending_invites": pending_invites,
+        # Sign-ups an admin still has to let in (roadmap UX-25): approved BEFORE they registered, so
+        # nothing ever reached the Access-requests queue and the badge used to read zero.
+        "pending_activations": pending_activations,
+        "email_configured": email_configured,
         "preferences": user.preferences or {},
     }
 

backend/app/routes/playlists.py

@@ -14,8 +14,8 @@ from app.db import get_db
 from app.feedquery import feed_columns, serialize
 from app.models import Channel, Playlist, PlaylistItem, User, Video, VideoState
 from app.sync.playlists import (
-    plan_push,
-    push_playlist,
+    merge_playlist,
+    plan_merge,
     recompute_dirty,
     repull_playlist,
     sync_user_playlists,
@@ -329,13 +329,13 @@ def push_plan(
     user: User = Depends(require_write_scope),
     db: Session = Depends(get_db),
 ) -> dict:
-    """Dry run: what 'Sync to YouTube' would do + the quota estimate, so the UI can show a
-    confirm. For a linked playlist this reads the live YouTube state (cheap, 1 unit/page).
-    Write scope is required (require_write_scope) — syncing is a YouTube write."""
+    """Dry run: what a two-way 'Sync to YouTube' merge would do (what each side gains/loses) +
+    the quota estimate, so the UI can show a confirm. For a linked playlist this reads the live
+    YouTube state (cheap, 1 unit/page). Write scope is required — syncing is a YouTube write."""
     pl = _pushable(db, user, playlist_id)
     try:
         with quota.attribute(user.id, quota.QuotaAction.PLAYLISTS_PUSH):
-            plan = plan_push(db, user, pl)
+            plan = plan_merge(db, user, pl)
     except YouTubeError:
         raise HTTPException(status_code=422, detail="Couldn't read the playlist on YouTube.")
     plan["remaining_today"] = quota.remaining_today(db)
@@ -349,14 +349,14 @@ def push(
     user: User = Depends(require_write_scope),
     db: Session = Depends(get_db),
 ) -> dict:
-    """Push a local playlist to YouTube (create it on first push, else reconcile to match
-    local — local wins). Refuses if the estimated quota exceeds what's left today, so a
-    big playlist can't strand half-pushed. Write scope required (require_write_scope)."""
+    """Two-way sync a local playlist with YouTube (create it on first push, else 3-way merge so
+    neither side loses an item). Refuses if the estimated quota exceeds what's left today, so a
+    big sync can't strand half-applied. Write scope required (require_write_scope)."""
     pl = _pushable(db, user, playlist_id)
     try:
         with quota.attribute(user.id, quota.QuotaAction.PLAYLISTS_PUSH):
             # Read the live playlist ONCE (linked playlists only) and share it with both the
-            # plan and the push, halving read-quota and closing the second read→write TOCTOU
+            # plan and the merge, halving read-quota and closing the second read→write TOCTOU
             # window. A fresh export (no yt_playlist_id) reads nothing.
             live = None
             if pl.yt_playlist_id:
@@ -365,13 +365,13 @@ def push(
                         list(yt.iter_playlist_items_with_ids(pl.yt_playlist_id)),
                         yt.get_playlist_snippet(pl.yt_playlist_id),
                     )
-            plan = plan_push(db, user, pl, live=live)
+            plan = plan_merge(db, user, pl, live=live)
             if plan["units_estimate"] > quota.remaining_today(db):
                 raise HTTPException(
                     status_code=429,
                     detail="Not enough YouTube quota left today for this sync.",
                 )
-            return push_playlist(db, user, pl, live=live)
+            return merge_playlist(db, user, pl, live=live)
     except YouTubeError:
         db.rollback()
         raise HTTPException(status_code=422, detail="YouTube playlist sync failed.")

backend/app/routes/plex/browse.py

@@ -2,6 +2,7 @@
 
 from fastapi import APIRouter, Depends, Query
 from sqlalchemy import (
+    Boolean,
     Integer,
     String,
     and_,
@@ -27,6 +28,7 @@ from app.plex import rollup
 from app.plex.cards import episode_card
 from app.plex.query import (
     FIELD_COLUMNS,
+    PLAYBACK_CLASSES,
     TS_CONFIG,
     LibraryFilters,
     apply_meta_filters,
@@ -36,6 +38,8 @@ from app.plex.query import (
     genres_col,
     meta_filter_conds,
     movie_status_case,
+    playable_conds,
+    playback_class_expr,
     show_status_case,
     split_csv,
     summary_col,
@@ -135,9 +139,13 @@ def unified_library(
                 PlexItem.originally_available_at.label("rel"),
                 PlexItem.duration_s.label("duration_s"),
                 PlexItem.playable.label("playable"),
+                PlexItem.transcode_hw.label("transcode_hw"),
                 cast(null(), Integer).label("season_count"),
                 func.coalesce(st.position_seconds, 0).label("position_seconds"),
                 m_status.label("status"),
+                # "last watched" sort key: when the movie was last resumed, else when it was marked
+                # watched. NULL for never-touched movies → nullslast sinks them (see the sort dict).
+                func.coalesce(st.progress_updated_at, st.watched_at).label("last_watched"),
                 (
                     func.ts_rank(vector_col(PlexItem, lang), tsq)
                     if tsq is not None
@@ -153,13 +161,15 @@ def unified_library(
             mq = mq.where(PlexItem.duration_s >= f.duration_min)
         if f.duration_max is not None:
             mq = mq.where(PlexItem.duration_s <= f.duration_max)
+        # Playback-class filter (movie-only — a show is an aggregate with no single class).
+        mq = mq.where(*playable_conds(split_csv(f.playable)))
         if tsq is not None:
             mq = mq.where(vector_match(PlexItem, lang, tsq))
         if recheck is not None:
             mq = mq.where(recheck(PlexItem, field, tsq, lang))
         selects.append(mq)
     if want_shows and grid_field:
-        agg = rollup.agg_subquery(db, user.id).subquery()
+        agg = rollup.agg_subquery(db, user.id, include_resumed=True).subquery()
         tot = func.coalesce(agg.c.total, 0)
         wat = func.coalesce(agg.c.watched, 0)
         inp = func.coalesce(agg.c.inprog, 0)
@@ -176,9 +186,13 @@ def unified_library(
                 PlexShow.originally_available_at.label("rel"),
                 cast(null(), Integer).label("duration_s"),
                 cast(null(), String).label("playable"),
+                cast(null(), Boolean).label("transcode_hw"),
                 PlexShow.child_count.label("season_count"),
                 literal(0).label("position_seconds"),
                 s_status.label("status"),
+                # Show leg's "last watched": max(resume/watched time) across the show's episodes (see
+                # rollup.agg_subquery include_resumed). NULL for a never-watched show → nullslast.
+                agg.c.resumed_at.label("last_watched"),
                 (
                     func.ts_rank(vector_col(PlexShow, lang), tsq)
                     if tsq is not None
@@ -212,6 +226,7 @@ def unified_library(
                 "rating": u.c.rating,
                 "duration": u.c.duration_s,
                 "release": u.c.rel,
+                "lastwatched": u.c.last_watched,
             }.get(sort, u.c.added_at)
             order = [(col.asc() if sort_dir == "asc" else col.desc()).nullslast()]
         order.append(u.c.rk.desc())
@@ -230,6 +245,7 @@ def unified_library(
                         "duration_seconds": r.duration_s,
                         "thumb": f"/api/plex/image/{r.rk}",
                         "playable": r.playable,
+                        "transcode_hw": r.transcode_hw,
                         "status": r.status,
                         "position_seconds": r.position_seconds,
                     }
@@ -305,6 +321,7 @@ def facets(
         "genres": [],
         "content_ratings": [],
         "studios": [],
+        "playable": [],
         "year_min": None,
         "year_max": None,
         "rating_max": None,
@@ -331,6 +348,9 @@ def facets(
                 query = query.where(model.duration_s >= pp["duration_min"])
             if with_dur and pp.get("duration_max") is not None:
                 query = query.where(model.duration_s <= pp["duration_max"])
+            # Playback-class filter (movie-only) — applied for the OTHER groups so an active class
+            # narrows them; the playable facet itself passes pp with playable=None (self-exclusion).
+            query = query.where(*playable_conds(split_csv(pp.get("playable"))))
             # Join watch-state and reuse the grid's exact movie state filter (unified_library) —
             # hidden movies never appear in the grid, so they must not inflate facet counts/bounds either.
             st = aliased(PlexState)
@@ -349,6 +369,7 @@ def facets(
     genre_counts: dict[str, int] = {}
     cr_counts: dict[str, int] = {}
     studio_counts: dict[str, int] = {}
+    playable_counts: dict[str, int] = {}
     years: list[int] = []
     ratings: list[float] = []
     durs: list[int] = []
@@ -413,6 +434,23 @@ def facets(
         )
         for s, c in db.execute(stq).all():
             studio_counts[s] = studio_counts.get(s, 0) + c
+        # Playback class (movie-only) — exclude its own so each class stays an addable OR option.
+        if kind_movie:
+            pcls = playback_class_expr()
+            pcq = (
+                wsq(
+                    select(pcls.label("cls"), func.count()),
+                    model,
+                    ids,
+                    {**p, "playable": None},
+                    kind_movie,
+                    True,
+                )
+                .where(pcls.isnot(None))
+                .group_by(pcls)
+            )
+            for cls, c in db.execute(pcq).all():
+                playable_counts[cls] = playable_counts.get(cls, 0) + c
         # Year bounds — exclude the year filter.
         by = db.execute(
             wsq(
@@ -470,6 +508,11 @@ def facets(
     # Same for the actively-selected studios, so a selected studio stays removable even at zero matches.
     for s in split_csv(f.studios):
         studio_counts.setdefault(s, 0)
+    # Keep an actively-selected playback class visible even at zero matches (the sidebar hides the whole
+    # section when its facet list is empty, which would trap a zero-result selection with no way to undo).
+    for c in split_csv(f.playable):
+        if c in PLAYBACK_CLASSES:
+            playable_counts.setdefault(c, 0)
     return {
         "genres": [
             {"value": g, "count": c} for g, c in sorted(genre_counts.items(), key=lambda kv: kv[0])
@@ -481,6 +524,12 @@ def facets(
             {"value": s, "count": c}
             for s, c in sorted(studio_counts.items(), key=lambda kv: (-kv[1], kv[0]))
         ],
+        # Fixed good→heavy order (not by count), so the class list reads as a severity scale.
+        "playable": [
+            {"value": c, "count": playable_counts[c]}
+            for c in PLAYBACK_CLASSES
+            if c in playable_counts
+        ],
         "year_min": min(years) if years else None,
         "year_max": max(years) if years else None,
         "rating_max": max(ratings) if ratings else None,

backend/app/routes/plex/detail.py

@@ -411,6 +411,10 @@ def item_detail(
         "year": it.year,
         "duration_seconds": it.duration_s,
         "playable": it.playable,
+        # Playback-class detail: HW/SW transcode split + the codec/bit-depth the info-page chip shows.
+        "transcode_hw": it.transcode_hw,
+        "codec_video": it.codec_video,
+        "video_bit_depth": it.video_bit_depth,
         "thumb": f"/api/plex/image/{it.rating_key}",
         "art": f"/api/plex/image/{it.rating_key}?variant=art",
         "library": _lib_key(db, it.library_id),

backend/app/routes/plex/playback.py

@@ -3,7 +3,8 @@
 import hashlib
 import os
 import tempfile
-from datetime import datetime, timezone
+import threading
+from datetime import datetime, timedelta, timezone
 
 import httpx
 from fastapi import (
@@ -155,6 +156,47 @@ _PROGRESS_MIN_S = 5
 
 _FINISH_MARGIN_S = 30
 
+# S2 write-back throttle: the resume position is now pushed to Plex on the periodic (non-final)
+# checkpoint too — not only on the final pause/unmount flush — so Plex (the source of truth) stays
+# current in near-real-time. To keep a single watch from spraying `/:/timeline` calls, a push is
+# rate-limited to at most one per item per user every _PUSH_THROTTLE_S seconds; a `final` checkpoint
+# (pause / seek / stop) always pushes immediately and resets the window. This is an in-memory, single-
+# process rate-limiter (the deployment is one FastAPI process): after a restart the map is empty, so at
+# most one extra push happens on the first checkpoint — harmless. It is NOT durable domain state.
+_PUSH_THROTTLE_S = 10
+_last_push_at: dict[tuple[int, int], datetime] = {}
+_push_throttle_lock = threading.Lock()
+
+
+def _should_push_resume(user_id: int, item_id: int, now: datetime, final: bool) -> bool:
+    """Whether to mirror this resume checkpoint to Plex now. `final` always pushes; a periodic tick
+    pushes only when ≥_PUSH_THROTTLE_S has elapsed since the last push for this (user, item). Records
+    `now` as the last-push time whenever it returns True so the window is measured from the real push
+    (and so `_resume_push_superseded` can drop an older, still-pending push — see there)."""
+    with _push_throttle_lock:
+        last = _last_push_at.get((user_id, item_id))
+        if final or last is None or (now - last).total_seconds() >= _PUSH_THROTTLE_S:
+            _last_push_at[(user_id, item_id)] = now
+            # Opportunistic eviction so the map can't grow unbounded over a long-lived process (one
+            # entry per item ever checkpointed). Anything older than a few windows is dead — a push
+            # completes in seconds, so a stale entry protects nothing.
+            if len(_last_push_at) > 2048:
+                cutoff = now - timedelta(seconds=_PUSH_THROTTLE_S * 6)
+                for k in [k for k, t in _last_push_at.items() if t < cutoff]:
+                    del _last_push_at[k]
+            return True
+        return False
+
+
+def _resume_push_superseded(user_id: int, item_id: int, intent: datetime) -> bool:
+    """True if a newer resume push for this (user, item) was scheduled after `intent`. Called at the
+    HTTP boundary of a background resume push: because periodic and seek/pause pushes are independent
+    background tasks with no ordering guard, an older still-pending periodic push could otherwise land
+    at Plex AFTER a newer backward-seek push and — with the Plex-authoritative pull — durably revive the
+    stale position. Skipping a superseded push keeps the last-scheduled position the one Plex settles on."""
+    with _push_throttle_lock:
+        return _last_push_at.get((user_id, item_id), intent) > intent
+
 
 @router.get("/person-image")
 def person_image(u: str, request: Request) -> Response:
@@ -178,6 +220,26 @@ def person_image(u: str, request: Request) -> Response:
     return imgcache.response(r.content, ct)
 
 
+def _push_resume_guarded(
+    user_id: int,
+    item_id: int,
+    rating_key: str,
+    time_ms: int,
+    duration_ms: int,
+    expect_ts: datetime | None,
+    intent: datetime,
+) -> None:
+    """Background entrypoint for a resume push that drops itself if a newer resume push for the same
+    (user, item) was scheduled after it (see `_resume_push_superseded`), then delegates to the real
+    push. This narrows the periodic-vs-seek write-ordering race to the (rare) case where the older push
+    has already left the process before the newer one is scheduled."""
+    if _resume_push_superseded(user_id, item_id, intent):
+        return
+    plex_watch.push_state_to_plex(
+        user_id, item_id, rating_key, "resume", time_ms, duration_ms, expect_ts
+    )
+
+
 def _push_watch(
     background: BackgroundTasks,
     db: Session,
@@ -187,10 +249,14 @@ def _push_watch(
     action: str,
     time_ms: int = 0,
     duration_ms: int = 0,
+    intent: datetime | None = None,
 ) -> None:
     """Schedule a best-effort Siftlode→Plex watch push, but only for a user whose owner link has
     push enabled — non-owner users never touch Plex. Guarding here (with the request session) avoids
-    spinning up a throwaway background session on every state change for the common no-link case."""
+    spinning up a throwaway background session on every state change for the common no-link case.
+
+    A `resume` push with an `intent` timestamp is routed through `_push_resume_guarded` so a superseded
+    (older) push can't land out of order; `watched`/`unwatched` scrobbles go straight through."""
     if plex_watch.link_for_push(db, user_id) is None:
         return
     # Capture the row's freshest timestamp NOW so the background push can tell if a newer local edit
@@ -202,6 +268,12 @@ def _push_watch(
         .scalars()
         .first()
     )
+    marker = plex_watch._state_marker(st)
+    if action == "resume" and intent is not None:
+        background.add_task(
+            _push_resume_guarded, user_id, item_id, rating_key, time_ms, duration_ms, marker, intent
+        )
+        return
     background.add_task(
         plex_watch.push_state_to_plex,
         user_id,
@@ -210,7 +282,7 @@ def _push_watch(
         action,
         time_ms,
         duration_ms,
-        plex_watch._state_marker(st),
+        marker,
     )
 
 
@@ -232,9 +304,10 @@ def item_progress(
 ) -> dict:
     """Checkpoint the resume position while playing (near the end → mark watched + clear it).
 
-    `final` (sent on the pause/pagehide/unmount flush, not the periodic 10s checkpoint) is what
-    debounces the Plex resume push: we mirror the settled position to Plex only on a final flush, so
-    a single watch doesn't spray `/:/timeline` calls at the server every 10 seconds."""
+    S2 write-back: the resume position is mirrored to Plex (the source of truth) on the periodic
+    checkpoint too, not only on the final flush — throttled to ≥_PUSH_THROTTLE_S per item (see
+    `_should_push_resume`). `final` (sent on pause / seek / pagehide / unmount) pushes immediately and
+    resets the throttle window, so Plex sees a settled position the instant the user pauses or seeks."""
     it = item_or_404(db, rating_key)
     position = max(0, int(body.position_seconds))
     duration = int(body.duration_seconds)
@@ -259,6 +332,10 @@ def item_progress(
         st.position_seconds = 0
         st.progress_updated_at = now
         st.synced_to_plex = False
+        # Terminal state for resume write-back: drop the throttle/ordering entry so the map doesn't
+        # retain a dead key for every finished item.
+        with _push_throttle_lock:
+            _last_push_at.pop((user.id, it.id), None)
         db.commit()
         # Immediate on the watched transition; skip a repeat scrobble if it was already watched
         # (a later checkpoint of the same finished item would otherwise bump Plex's viewCount again).
@@ -280,10 +357,13 @@ def item_progress(
         db.add(st)
     st.position_seconds = position
     st.progress_updated_at = now
-    if final:
+    push_now = _should_push_resume(user.id, it.id, now, final)
+    if push_now:
+        # Mark dirty before the (background) push so the reconcile knows to re-push if it fails, and so
+        # `push_state_to_plex` can settle synced_to_plex once Plex confirms.
         st.synced_to_plex = False
     db.commit()
-    if final:
+    if push_now:
         _push_watch(
             background,
             db,
@@ -293,6 +373,7 @@ def item_progress(
             "resume",
             position * 1000,
             duration * 1000,
+            intent=now,
         )
     return {"position_seconds": position}
 
@@ -451,15 +532,13 @@ def stream_session(
     db: Session = Depends(get_db),
 ) -> dict:
     """Prepare playback from `start` seconds. Direct-playable files are served raw; remux files
-    (re)start an HLS session at the offset (seek-restart); transcode (HEVC/VP9) is P3. Selecting a
-    non-default audio track (`audio` = stream ordinal) forces the HLS path so the chosen audio can be
-    muxed in. Subtitles are independent WebVTT tracks (GET /subtitle) — no session restart."""
+    (re)start an HLS session at the offset (seek-restart, video stream-copied); transcode files (non-h264:
+    HEVC/VP9/AV1/…) take the same HLS path but with the video re-encoded to H.264 (VAAPI or libx264).
+    Selecting a non-default audio track (`audio` = stream ordinal) forces the HLS path so the chosen audio
+    can be muxed in. Subtitles are independent WebVTT tracks (GET /subtitle) — no session restart."""
     plex_stream.reap_idle()  # opportunistic cleanup of idle sessions on each new playback
     it = item_or_404(db, rating_key)
-    if it.playable == "transcode":
-        raise HTTPException(
-            status_code=501, detail="This format needs transcoding (a later phase)."
-        )
+    transcode = it.playable == "transcode"
     # `multi` (item has ≥2 audio tracks) forces the HLS path so ALL audio tracks ship as renditions and
     # the client can switch audio without a restart — even for otherwise direct-playable files.
     if it.playable == "direct" and audio is None and not aoff and not multi:
@@ -470,15 +549,21 @@ def stream_session(
         }
     if plex_paths.local_media_path(db, it.file_path) is None:
         raise HTTPException(status_code=404, detail="Media file not found on disk")
-    s = plex_stream.start_session(db, it, start, audio, aoff, multi)
+    s = plex_stream.start_session(db, it, start, audio, aoff, multi, transcode=transcode)
     if s is None:
         raise HTTPException(status_code=404, detail="Media file not found on disk")
     # Report the REAL media start (the keyframe ffmpeg landed on, which hls.js zero-bases to), not the
     # requested offset — the client's absolute clock and the subtitle cue-shift both key off this.
+    # `transcode`/`hw`/`tonemap` let the player show an honest cold-start ("Preparing stream…") and
+    # surface the active mode + encoder in the stats overlay (`tonemap` = the HW HDR→SDR path); both
+    # segment streams are otherwise identical.
     return {
         "mode": "hls",
         "start_s": s.media_start_s,
         "url": f"/api/plex/stream/{it.rating_key}/hls/{s.entry}",
+        "transcode": s.transcode,
+        "hw": s.hw,
+        "tonemap": s.tonemap,
     }
 
 

backend/app/routes/public.py

@@ -122,9 +122,25 @@ def watch_file(token: str, g: str | None = None, db: Session = Depends(get_db)):
         raise HTTPException(status_code=404, detail="This video is no longer available.")
 
     filename = storage.download_filename(asset.title or "video", asset.container, path)
+    # The served Content-Type comes from the asset's ffprobe-verified media_kind + a container
+    # allow-list (storage.served_media_type) — NEVER guessed from the file's own extension. A generic
+    # 'file' (and any media whose container we don't positively recognise, e.g. a media/HTML polyglot
+    # named "evil.html") returns None → a neutral force-download attachment, so arbitrary uploaded
+    # HTML/SVG can't execute inline on this login-free public origin. A recognised media container is
+    # served with its real audio/video type, inline unless the link forces a download so it can play
+    # in the watch page. Both are range-aware (FileResponse → 206) for seeking/resume.
+    media_type = storage.served_media_type(asset.media_kind, asset.container)
+    if media_type is None:
+        return FileResponse(
+            path,
+            filename=filename,
+            media_type="application/octet-stream",
+            content_disposition_type="attachment",
+        )
     disposition = "attachment" if link.allow_download else "inline"
-    # Starlette's FileResponse honours the Range header (206) for seeking/scrubbing.
-    return FileResponse(path, filename=filename, content_disposition_type=disposition)
+    return FileResponse(
+        path, filename=filename, media_type=media_type, content_disposition_type=disposition
+    )
 
 
 @router.get("/watch/{token}/poster.jpg")

backend/app/routes/setup.py

@@ -14,6 +14,7 @@ from sqlalchemy import select
 from sqlalchemy.orm import Session
 
 from app import email as email_mod
+from app import mailtext
 from app import state, sysconfig
 from app.auth import PASSWORD_MIN_LEN
 from app.db import get_db
@@ -103,6 +104,9 @@ def setup_config(settings_map: dict[str, Any], db: Session = Depends(require_set
 
 class SetupTestEmailIn(BaseModel):
     to: str = ""
+    # The wizard's page language. No account exists yet on a fresh instance, so this is the only
+    # thing that can say what language to write in; anything unsupported falls back to English.
+    lang: str | None = None
 
 
 @router.post("/test-email")
@@ -111,7 +115,7 @@ def setup_test_email(body: SetupTestEmailIn, db: Session = Depends(require_setup
     to = body.to.strip()
     if "@" not in to:
         raise HTTPException(status_code=400, detail="Enter a valid email address.")
-    if not email_mod.send_test(to):
+    if not email_mod.send_test(to, mailtext.normalize(body.lang)):
         raise HTTPException(status_code=400, detail="Couldn't send — check the SMTP settings.")
     return {"ok": True}
 

backend/app/routes/tags.py

@@ -8,10 +8,22 @@ from app.auth import current_user
 from app.db import get_db
 from app.models import ChannelTag, Tag, User
 from app.routes._common import owned_or_404
+from app.sync.tagsuggest import compute_tag_suggestions
 
 router = APIRouter(prefix="/api/tags", tags=["tags"])
 
 
+@router.get("/suggestions")
+def tag_suggestions(
+    user: User = Depends(current_user), db: Session = Depends(get_db)
+) -> dict[str, list[dict]]:
+    """Suggested user tags for this user's still-untagged subscribed channels, learned from the
+    auto-tag pattern of the channels they HAVE tagged (see app.sync.tagsuggest). Read-only — the
+    Channel Manager shows these as one-tap-accept chips; accepting posts to the normal attach-tag
+    endpoint. Keyed by channel id; channels with no suggestion are omitted."""
+    return compute_tag_suggestions(db, user)
+
+
 @router.get("")
 def list_tags(user: User = Depends(current_user), db: Session = Depends(get_db)) -> list[dict]:
     rows = db.execute(

backend/app/sync/playlists.py

@@ -1,14 +1,16 @@
 """YouTube playlist sync, both directions. Read: mirror each user's own YouTube playlists
-into local `source='youtube'` playlists (kept fresh by the scheduler). Write-back: push local
-edits out to YouTube (`plan_push` / `push_playlist`), behind the optional write scope.
+into local `source='youtube'` playlists (kept fresh by the scheduler). Write-back: two-way sync
+local edits with YouTube (`plan_merge` / `merge_playlist`), behind the optional write scope.
 
 YouTube's special Watch Later / History playlists are not exposed by the Data API and are
 never synced. Videos in a playlist that aren't in our shared catalog yet are fetched and
 ingested (with a stub channel) so the mirror is faithful."""
 
 import hashlib
+import json
 import logging
 from collections.abc import Callable
+from dataclasses import dataclass
 from datetime import datetime, timezone
 from typing import TypeVar
 
@@ -42,6 +44,57 @@ def current_fingerprint(db: Session, pl: Playlist) -> str:
     return fingerprint(pl.name, _local_video_ids(db, pl))
 
 
+def _dump_ids(ids: list[str]) -> str:
+    """Serialize the ordered id list stored as the 3-way-merge baseline (`synced_video_ids`)."""
+    return json.dumps(ids)
+
+
+def _load_baseline(pl: Playlist) -> tuple[list[str] | None, set[str]]:
+    """Parse `synced_video_ids` into (ordered id set, un-ingestable id set). Two on-disk forms:
+    a plain JSON list (legacy / no un-ingestable ids) or `{"ids": [...], "unavailable": [...]}`.
+    `unavailable` = YouTube-only videos that exist on YouTube but the Data API won't return
+    (private/deleted/region-locked), so they never became local rows — tracked so the merge can
+    skip them instead of forever re-classifying them as a YouTube-add (they'd never converge)."""
+    if not pl.synced_video_ids:
+        return None, set()
+    try:
+        val = json.loads(pl.synced_video_ids)
+    except (ValueError, TypeError):
+        return None, set()
+    if isinstance(val, list):
+        return [str(v) for v in val], set()
+    if isinstance(val, dict):
+        raw_ids = val.get("ids")
+        ids = [str(v) for v in raw_ids] if isinstance(raw_ids, list) else None
+        raw_un = val.get("unavailable")
+        un = {str(v) for v in raw_un} if isinstance(raw_un, list) else set()
+        return ids, un
+    return None, set()
+
+
+def parse_baseline(pl: Playlist) -> list[str] | None:
+    """The last-synced ordered id set, or None when no baseline has been recorded yet (a fresh
+    export, or a link created before S7). None makes the first merge union losslessly."""
+    return _load_baseline(pl)[0]
+
+
+def parse_unavailable(pl: Playlist) -> set[str]:
+    """The last-synced set of un-ingestable-but-live YouTube ids (see `_load_baseline`)."""
+    return _load_baseline(pl)[1]
+
+
+def _set_baseline(pl: Playlist, ids: list[str], unavailable: list[str] | None = None) -> None:
+    """Record `ids` as both the hash (drives `dirty`, over the local ids only) and the raw ordered
+    set (drives merge). `unavailable` = un-ingestable-but-live YouTube ids to carry forward so the
+    next merge skips them; stored only when non-empty (keeps the common case a plain list)."""
+    pl.synced_fingerprint = fingerprint(pl.name, ids)
+    if unavailable:
+        pl.synced_video_ids = json.dumps({"ids": ids, "unavailable": list(unavailable)})
+    else:
+        pl.synced_video_ids = _dump_ids(ids)
+    pl.dirty = False
+
+
 def recompute_dirty(db: Session, pl: Playlist) -> None:
     """Set `dirty` by comparing the current state to the synced baseline. Unlinked lists
     (and Watch later) are never dirty; a missing baseline counts as dirty (unknown YT state)."""
@@ -116,12 +169,18 @@ def _replace_items_from_youtube(
         if v in present and v not in seen:
             seen.add(v)
             ordered.append(v)
+    _set_local_items(db, pl, ordered)
+    # After a pull/reset local == YouTube, so this ordered set IS the new merge baseline.
+    _set_baseline(pl, ordered)
+    return ordered
+
+
+def _set_local_items(db: Session, pl: Playlist, ordered: list[str]) -> None:
+    """Authoritatively replace `pl`'s local items with `ordered` (positions 0..n). The caller
+    is responsible for having ensured every id exists in the catalog."""
     db.execute(delete(PlaylistItem).where(PlaylistItem.playlist_id == pl.id))
     for pos, vid in enumerate(ordered):
         db.add(PlaylistItem(playlist_id=pl.id, video_id=vid, position=pos))
-    pl.synced_fingerprint = fingerprint(pl.name, ordered)
-    pl.dirty = False
-    return ordered
 
 
 def sync_user_playlists(db: Session, user: User) -> dict:
@@ -216,22 +275,91 @@ def _reorder_moves(current: list[str], desired: list[str]) -> int:
     return moves
 
 
-def plan_push(db: Session, user: User, pl: Playlist, *, live=None) -> dict:
-    """Compute (without writing) what pushing this local playlist to YouTube would do:
-    create vs update, how many inserts/deletes/reorders, the quota estimate, and whether
-    YouTube has diverged (items present there that local will remove). Costs read units
-    (1/page) for a linked playlist; nothing for a fresh export. `live` = a pre-fetched
-    (current_items, snippet) tuple so the caller can share one read with push_playlist."""
-    desired = _local_video_ids(db, pl)
+@dataclass
+class MergePlan:
+    """The 3-way merge of a linked playlist: what each side gains and loses so neither side
+    loses an item, plus the merged order. `final` is the id set both sides end up with."""
+
+    final: list[str]  # merged order (local order, YouTube-only adds appended)
+    add_to_yt: list[str]  # local-adds to push out to YouTube
+    add_to_local: list[str]  # YouTube-adds to pull into Siftlode
+    remove_from_yt: list[str]  # items deleted locally that are still on YouTube
+    remove_from_local: list[str]  # items deleted on YouTube that are still local
+    reorders: int  # estimated YouTube playlistItems.update moves to reach `final`
+    baseline_known: bool
+
+
+def merge_plan(
+    baseline: list[str] | None,
+    local: list[str],
+    youtube: list[str],
+    unavailable: set[str] | None = None,
+) -> MergePlan:
+    """Pure 3-way merge. Classify each id against the last-synced `baseline`:
+    - in local but not youtube, not deleted → add to YouTube (a local-add)
+    - in youtube but not local, not deleted → add to Siftlode (a YouTube-add)
+    - in baseline but gone from local → a genuine local delete → propagate to YouTube
+    - in baseline but gone from youtube → a genuine YouTube delete → propagate to Siftlode
+    With NO baseline (first-ever merge) we can't tell an add from a delete, so we UNION both
+    sides (never delete) — the lossless default. Merged order: local order first, YouTube-only
+    additions appended in their YouTube order.
+    `unavailable` = known un-ingestable-but-live YouTube ids: dropped from the YouTube side up
+    front so they're never re-classified as a YouTube-add (they can't ingest) nor as a local
+    delete (they were never local) — otherwise such a video would make the playlist never
+    converge. They stay in place on YouTube, untouched by this merge."""
+    un = set(unavailable or ())
+    L = list(dict.fromkeys(local))
+    Y = [v for v in dict.fromkeys(youtube) if v not in un]
+    Lset, Yset = set(L), set(Y)
+    if baseline is None:
+        add_to_yt = [v for v in L if v not in Yset]
+        add_to_local = [v for v in Y if v not in Lset]
+        remove_from_yt: list[str] = []
+        remove_from_local: list[str] = []
+        final = L + [v for v in Y if v not in Lset]
+    else:
+        B = set(baseline)
+        deleted_local = B - Lset  # was synced, removed on our side
+        deleted_yt = B - Yset  # was synced, removed on YouTube's side
+        gone = deleted_local | deleted_yt
+        remove_from_yt = [v for v in Y if v in deleted_local]
+        remove_from_local = [v for v in L if v in deleted_yt]
+        add_to_yt = [v for v in L if v not in Yset and v not in gone]
+        add_to_local = [v for v in Y if v not in Lset and v not in gone]
+        final = [v for v in L if v not in gone] + [v for v in Y if v not in Lset and v not in gone]
+    final_set = set(final)
+    # On YouTube, after membership reconciliation the order is current-kept + inserts appended;
+    # the reorder pass then moves items into `final`.
+    after_membership = [v for v in Y if v in final_set] + add_to_yt
+    reorders = _reorder_moves(after_membership, final)
+    return MergePlan(
+        final=final,
+        add_to_yt=add_to_yt,
+        add_to_local=add_to_local,
+        remove_from_yt=remove_from_yt,
+        remove_from_local=remove_from_local,
+        reorders=reorders,
+        baseline_known=baseline is not None,
+    )
+
+
+def plan_merge(db: Session, user: User, pl: Playlist, *, live=None) -> dict:
+    """Compute (without writing) what a two-way sync of this playlist would do: create vs
+    update, how many items each side gains/loses, reorders, and the quota estimate (YouTube
+    writes only — local edits are free). Reads live YouTube state (1 unit/page) for a linked
+    playlist; nothing for a fresh export. `live` = a pre-fetched (current_items, snippet) tuple
+    so the caller can share one read with merge_playlist."""
+    local = _local_video_ids(db, pl)
     if not pl.yt_playlist_id:
-        ops = 1 + len(desired)  # create the playlist + one insert per video
+        ops = 1 + len(local)  # create the playlist + one insert per video
         return {
             "action": "create",
-            "to_insert": len(desired),
-            "to_delete": 0,
+            "add_yt": len(local),
+            "add_local": 0,
+            "remove_yt": 0,
+            "remove_local": 0,
             "to_reorder": 0,
             "rename": False,
-            "yt_extra": 0,
             "units_estimate": ops * WRITE_UNIT_COST,
         }
     if live is not None:
@@ -241,23 +369,17 @@ def plan_push(db: Session, user: User, pl: Playlist, *, live=None) -> dict:
             current = list(yt.iter_playlist_items_with_ids(pl.yt_playlist_id))
             snippet = yt.get_playlist_snippet(pl.yt_playlist_id)
     rename = bool(snippet) and (snippet.get("title") or "") != pl.name
-    cur_vids = [it["video_id"] for it in current]
-    cur_set = set(cur_vids)
-    desired_set = set(desired)
-    to_insert = [v for v in desired if v not in cur_set]
-    to_delete = [v for v in cur_vids if v not in desired_set]
-    # After membership reconciliation, the YT order is current-minus-deletes plus inserts
-    # appended; the reorder pass then moves items into the desired order.
-    after_membership = [v for v in cur_vids if v in desired_set] + to_insert
-    reorders = _reorder_moves(after_membership, desired)
-    ops = len(to_insert) + len(to_delete) + reorders + (1 if rename else 0)
+    yt_ids = [it["video_id"] for it in current]
+    mp = merge_plan(parse_baseline(pl), local, yt_ids, parse_unavailable(pl))
+    ops = len(mp.add_to_yt) + len(mp.remove_from_yt) + mp.reorders + (1 if rename else 0)
     return {
         "action": "update",
-        "to_insert": len(to_insert),
-        "to_delete": len(to_delete),
-        "to_reorder": reorders,
+        "add_yt": len(mp.add_to_yt),
+        "add_local": len(mp.add_to_local),
+        "remove_yt": len(mp.remove_from_yt),
+        "remove_local": len(mp.remove_from_local),
+        "to_reorder": mp.reorders,
         "rename": rename,
-        "yt_extra": len(to_delete),
         "units_estimate": ops * WRITE_UNIT_COST,
     }
 
@@ -327,13 +449,16 @@ class _Breaker:
         return out
 
 
-def push_playlist(db: Session, user: User, pl: Playlist, *, live=None) -> dict:
-    """Push a local playlist to YouTube: create it if needed, then reconcile membership
-    and order so YouTube matches local (local wins). Marks the playlist clean on success.
+def merge_playlist(db: Session, user: User, pl: Playlist, *, live=None) -> dict:
+    """Two-way sync a local playlist with YouTube: create it on first push, else 3-way MERGE
+    both sides so an item added (or deleted) on either side survives — no side wins wholesale.
+    Local edits are applied directly; YouTube edits go through the failure breaker. On full
+    success the merged set becomes the new baseline and the playlist is marked clean; on any
+    YouTube failure the baseline is left untouched so the next sync retries and converges.
     Caller must have checked the write scope and the quota budget. `live` = a pre-fetched
-    (current_items, snippet) tuple (from plan_push's read) to avoid a second live page-through."""
-    desired = _local_video_ids(db, pl)
-    inserted = deleted = reordered = created = 0
+    (current_items, snippet) tuple (from plan_merge's read) to avoid a second page-through."""
+    local = _local_video_ids(db, pl)
+    inserted = deleted = reordered = created = pulled = removed_local = 0
     failures: list[str] = []
     breaker = _Breaker()
     with YouTubeClient(db, user) as yt:
@@ -341,8 +466,8 @@ def push_playlist(db: Session, user: User, pl: Playlist, *, live=None) -> dict:
             pl.yt_playlist_id = yt.create_playlist(pl.name)
             db.commit()
             created = 1
-            # Brand-new playlist: just append every video in order.
-            for vid in desired:
+            # Brand-new playlist: just append every local video in order.
+            for vid in local:
                 added = breaker.run(
                     lambda v=vid: yt.add_playlist_item(pl.yt_playlist_id, v),
                     lambda v=vid: failures.append(v),
@@ -350,60 +475,95 @@ def push_playlist(db: Session, user: User, pl: Playlist, *, live=None) -> dict:
                 if not isinstance(added, _Failed):
                     inserted += 1
             if not failures:
-                pl.synced_fingerprint = fingerprint(pl.name, desired)
-                pl.dirty = False
+                _set_baseline(pl, local)
             db.commit()
             return {
                 "created": created,
                 "inserted": inserted,
                 "deleted": deleted,
                 "reordered": reordered,
+                "pulled": pulled,
+                "removed_local": removed_local,
                 "failures": failures,
                 "aborted": breaker.tripped,
                 "yt_playlist_id": pl.yt_playlist_id,
             }
 
-        # Existing link: diff against the live YouTube state (reuse plan_push's read if given).
+        # Existing link: 3-way merge against the live YouTube state (reuse plan_merge's read).
         if live is not None:
             current, snippet = live
         else:
             snippet = yt.get_playlist_snippet(pl.yt_playlist_id)
             current = list(yt.iter_playlist_items_with_ids(pl.yt_playlist_id))
+        item_id_by_vid = {it["video_id"]: it["item_id"] for it in current}
+        yt_ids = [it["video_id"] for it in current]
+        # Re-attempt ingestion of ids previously marked un-ingestable that are still on YouTube: a
+        # video that has since become available (e.g. private→public) should re-enter the merge, not
+        # stay skipped forever. Those that still won't ingest remain filtered (`effective_unavailable`).
+        prev_unavailable = parse_unavailable(pl)
+        still_listed = [v for v in yt_ids if v in prev_unavailable]
+        if still_listed:
+            _ensure_videos(db, yt, still_listed)
+            healed = set(
+                db.execute(select(Video.id).where(Video.id.in_(still_listed))).scalars().all()
+            )
+            effective_unavailable = prev_unavailable - healed
+        else:
+            effective_unavailable = prev_unavailable
+        mp = merge_plan(parse_baseline(pl), local, yt_ids, effective_unavailable)
+
+        # --- Siftlode side (free, direct): pull YouTube-adds in, drop YouTube-deletes, land the
+        # merged order authoritatively. Do this first so local reflects the merge even if a later
+        # YouTube write trips the breaker.
+        _ensure_videos(db, yt, mp.add_to_local)
+        # Only the ids that actually exist in the catalog can become local rows (a private/deleted
+        # YouTube video won't ingest); keep the merged order, dropping any that didn't materialize.
+        present = (
+            set(db.execute(select(Video.id).where(Video.id.in_(mp.final))).scalars().all())
+            if mp.final
+            else set()
+        )
+        final_local = [v for v in mp.final if v in present]
+        pulled = len([v for v in mp.add_to_local if v in present])
+        removed_local = len(mp.remove_from_local)
+        _set_local_items(db, pl, final_local)
+        db.commit()
+
+        # --- YouTube side (metered, breaker-guarded).
         if snippet is not None and (snippet.get("title") or "") != pl.name:
             try:
                 yt.update_playlist_title(pl.yt_playlist_id, pl.name)
             except YouTubeError:
                 failures.append("title")
-        item_id_by_vid = {it["video_id"]: it["item_id"] for it in current}
-        cur_vids = [it["video_id"] for it in current]
-        desired_set = set(desired)
-        # Delete extras (local is authoritative).
-        for it in current:
-            if it["video_id"] not in desired_set:
-                dropped = breaker.run(
-                    lambda i=it: yt.delete_playlist_item(i["item_id"]),
-                    lambda i=it: failures.append(i["video_id"]),
-                )
-                if not isinstance(dropped, _Failed):
-                    deleted += 1
-        # Insert missing (append; the reorder pass below fixes positions).
-        cur_set = set(cur_vids)
-        for vid in desired:
-            if vid not in cur_set:
-                item_id = breaker.run(
-                    lambda v=vid: yt.add_playlist_item(pl.yt_playlist_id, v),
-                    lambda v=vid: failures.append(v),
-                )
-                if not isinstance(item_id, _Failed):
-                    item_id_by_vid[vid] = item_id
-                    inserted += 1
-        # Reorder to match `desired` via insertion-sort moves over a local model.
-        model = [v for v in cur_vids if v in desired_set] + [
-            v for v in desired if v not in cur_set and v in item_id_by_vid
+        # Propagate genuine local deletes.
+        for vid in mp.remove_from_yt:
+            item_id = item_id_by_vid.get(vid)
+            if item_id is None:
+                continue
+            dropped = breaker.run(
+                lambda i=item_id: yt.delete_playlist_item(i),
+                lambda v=vid: failures.append(v),
+            )
+            if not isinstance(dropped, _Failed):
+                deleted += 1
+                item_id_by_vid.pop(vid, None)
+        # Insert local-adds (append; the reorder pass below fixes positions).
+        for vid in mp.add_to_yt:
+            item_id = breaker.run(
+                lambda v=vid: yt.add_playlist_item(pl.yt_playlist_id, v),
+                lambda v=vid: failures.append(v),
+            )
+            if not isinstance(item_id, _Failed):
+                item_id_by_vid[vid] = item_id
+                inserted += 1
+        # Reorder YouTube to match `final` via insertion-sort moves over a local model.
+        final_set = set(mp.final)
+        model = [v for v in yt_ids if v in final_set and v in item_id_by_vid] + [
+            v for v in mp.add_to_yt if v in item_id_by_vid
         ]
-        for i, want in enumerate(desired):
+        for i, want in enumerate(mp.final):
             if want not in item_id_by_vid:
-                continue  # failed insert; skip
+                continue  # deleted-from-YT or failed insert; skip
             if i < len(model) and model[i] == want:
                 continue
             moved = breaker.run(
@@ -419,14 +579,23 @@ def push_playlist(db: Session, user: User, pl: Playlist, *, live=None) -> dict:
             model.pop(j)
             model.insert(i, want)
         if not failures:
-            pl.synced_fingerprint = fingerprint(pl.name, desired)
-            pl.dirty = False
+            # Carry forward un-ingestable-but-live YouTube ids so the next merge skips them
+            # (see merge_plan): this run's failed pulls, plus prior ones still on YouTube, minus
+            # any that have since left YouTube. Recomputed each success → self-healing.
+            yt_id_set = set(yt_ids)
+            unavailable = sorted(
+                (effective_unavailable | {v for v in mp.add_to_local if v not in present})
+                & yt_id_set
+            )
+            _set_baseline(pl, final_local, unavailable)
         db.commit()
     return {
         "created": created,
         "inserted": inserted,
         "deleted": deleted,
         "reordered": reordered,
+        "pulled": pulled,
+        "removed_local": removed_local,
         "failures": failures,
         "aborted": breaker.tripped,
         "yt_playlist_id": pl.yt_playlist_id,

backend/app/sync/tagsuggest.py

@@ -0,0 +1,131 @@
+"""Suggest a user's own manual tags for channels they haven't tagged yet.
+
+The signal is the auto-tagger's *topic* output: each channel carries ``source='auto'`` topic
+ChannelTags (see ``autotag.py``). For every user tag T the user has applied to enough channels,
+we learn which topics are *characteristic* of T (present in a high fraction of the channels the
+user tagged T), then suggest T for any still-untagged channel whose own topics cover enough of
+that profile.
+
+Language auto-tags are deliberately EXCLUDED from the signal: they are near-universal within a
+language ("English" is on most channels), so they don't discriminate — including them floods the
+result (measured on real data: every untagged channel got a suggestion, most on a shared language
+alone). Topic overlap is what makes "you tagged similar channels this way" meaningful.
+
+Purely read-only and deterministic — the Channel Manager surfaces the result as one-tap-accept
+"ghost" chips; nothing is written here (D4 = suggest-and-confirm, no silent auto-apply). The
+thresholds are tuning constants rather than admin knobs on purpose: they mirror how ``autotag.py``
+keeps its mappings inline, and sysconfig only stores int/str/bool (no float), so a knob would mean
+storing percentages — not worth the surface for values an operator has no reason to tune per-install.
+"""
+
+from collections import Counter
+
+from sqlalchemy import select
+from sqlalchemy.orm import Session
+
+from app.models import ChannelTag, Subscription, Tag, User
+
+# A user tag needs at least this many manually-tagged example channels before we trust its
+# profile — fewer is noise (one gaming-cooking channel shouldn't make "cooking" mean "gaming").
+MIN_EXAMPLES = 3
+# A topic counts as *characteristic* of a user tag when it appears in ≥60% of that tag's example
+# channels. High enough that an incidental shared topic (one channel's stray category) doesn't
+# enter the profile, low enough to survive a couple of outliers in a small example set.
+CHAR_SUPPORT = 0.6
+# Suggest tag T for channel C when C's topics cover ≥60% of T's characteristic topics. The
+# intersection-over-profile shape means a partial match scores proportionally: 1 topic of a
+# 2-topic profile = 0.5 (dropped), 2 of 3 = 0.67 (kept). Tuned against real data to surface
+# strong topical matches without flooding — 0.5 let a single shared topic carry a suggestion.
+SUGGEST_THRESHOLD = 0.6
+# A suggestion at/above this score is "high confidence" — a full-profile topic match — and is the
+# only kind the UI's "Accept all confident" action touches. Never applied silently (see docstring).
+AUTOAPPLY_THRESHOLD = 0.9
+# Cap suggestions per channel so a busy channel's chip row stays legible.
+MAX_PER_CHANNEL = 3
+
+
+def compute_tag_suggestions(db: Session, user: User) -> dict[str, list[dict]]:
+    """Map each of the user's still-untagged subscribed channels to suggested user tags.
+
+    Returns ``{channel_id: [{"tag_id": int, "confidence": float}, ...]}`` — ordered best-first,
+    capped at ``MAX_PER_CHANNEL``. Channels with no suggestion are omitted (empty dict when the
+    user has no tag with a usable profile). Deterministic for a fixed DB state.
+    """
+    # Candidate universe: the channels this user is subscribed to. `subscribed` (incl. hidden) is the
+    # SIGNAL set — a hidden channel is still a valid example / topic-feature source, since hiding only
+    # affects the feed, not the tagging pattern. `hidden` is excluded as a suggestion TARGET below (the
+    # Channel Manager shows ghost chips only on non-hidden rows, so suggesting for hidden channels would
+    # inflate the header count past what's shown and let bulk-accept tag channels the user can't see).
+    subs = db.execute(
+        select(Subscription.channel_id, Subscription.hidden).where(Subscription.user_id == user.id)
+    ).all()
+    subscribed: set[str] = {cid for cid, _ in subs}
+    hidden: set[str] = {cid for cid, h in subs if h}
+    if not subscribed:
+        return {}
+
+    # The user's manual tag links: tag_id -> example channels, and each channel's user-tag set (so
+    # a channel with ANY user tag is excluded from "untagged"). Intersect with `subscribed`: unsubscribe
+    # deletes the Subscription but NOT the source='user' ChannelTag, so a tagged-then-unsubscribed
+    # channel would otherwise stay an "example" — inflating a profile's CHAR_SUPPORT denominator while
+    # contributing zero features (features are scanned over `subscribed` only), dropping characteristic
+    # topics. Keeping examples ⊆ subscribed makes the support fraction honest.
+    examples: dict[int, set[str]] = {}
+    user_tagged: set[str] = set()
+    for tag_id, cid in db.execute(
+        select(ChannelTag.tag_id, ChannelTag.channel_id).where(
+            ChannelTag.user_id == user.id, ChannelTag.source == "user"
+        )
+    ).all():
+        if cid not in subscribed:
+            continue
+        examples.setdefault(tag_id, set()).add(cid)
+        user_tagged.add(cid)
+
+    # Topic features per channel: the auto TOPIC tags on the candidate channels. Language auto-tags
+    # are joined out (Tag.category) — they don't discriminate (see the module docstring).
+    features: dict[str, set[int]] = {}
+    for cid, tid in db.execute(
+        select(ChannelTag.channel_id, ChannelTag.tag_id)
+        .join(Tag, Tag.id == ChannelTag.tag_id)
+        .where(
+            ChannelTag.user_id.is_(None),
+            ChannelTag.source == "auto",
+            ChannelTag.channel_id.in_(subscribed),
+            Tag.category == "topic",
+        )
+    ).all():
+        features.setdefault(cid, set()).add(tid)
+
+    # Characteristic-feature profile per user tag with enough examples.
+    profiles: dict[int, set[int]] = {}
+    for tag_id, ex in examples.items():
+        if len(ex) < MIN_EXAMPLES:
+            continue
+        counts: Counter[int] = Counter()
+        for cid in ex:
+            counts.update(features.get(cid, ()))
+        threshold = CHAR_SUPPORT * len(ex)
+        chars = {f for f, c in counts.items() if c >= threshold}
+        if chars:
+            profiles[tag_id] = chars
+    if not profiles:
+        return {}
+
+    suggestions: dict[str, list[dict]] = {}
+    for cid in subscribed:
+        if cid in hidden or cid in user_tagged:  # hidden → no chips shown; tagged → not "untagged"
+            continue
+        cfeat = features.get(cid)
+        if not cfeat:
+            continue
+        scored = [(tag_id, len(cfeat & chars) / len(chars)) for tag_id, chars in profiles.items()]
+        hits = [(tid, s) for tid, s in scored if s >= SUGGEST_THRESHOLD]
+        if not hits:
+            continue
+        # Best score first; tag_id as a stable tie-break so the order is deterministic.
+        hits.sort(key=lambda x: (-x[1], x[0]))
+        suggestions[cid] = [
+            {"tag_id": tid, "confidence": round(s, 3)} for tid, s in hits[:MAX_PER_CHANNEL]
+        ]
+    return suggestions

backend/app/sysconfig.py

@@ -127,6 +127,10 @@ SPECS: tuple[ConfigSpec, ...] = (
         min=1,
         max=100_000,
     ),
+    # min=1, NOT 0: the per-file cap is enforced as `if cap and size > cap`, so a stored 0 would read
+    # as falsy and SILENTLY disable the limit (an unbounded streamed write to the volume). Floor it at
+    # 1 so the cap is always active; the overall footprint is separately bounded by the byte quota.
+    ConfigSpec("download_upload_max_bytes", "int", "downloads", "download_upload_max_bytes", min=1),
     ConfigSpec(
         "download_retention_days", "int", "downloads", "download_retention_days", min=0, max=3_650
     ),
@@ -155,6 +159,14 @@ SPECS: tuple[ConfigSpec, ...] = (
     ConfigSpec("plex_overlay_map", "str", "plex", "plex_overlay_map"),
     # (plex_sync_interval_min is tuned from the Scheduler dashboard, not here — it's a scheduler job.)
     ConfigSpec("plex_max_transcodes", "int", "plex", "plex_max_transcodes", min=0, max=16),
+    # Transcode re-encode tuning (E6 S1). hw = "auto"|"on"|"off" (free-text, like search_source); the
+    # libx264 knobs apply only to the software fallback. crf 0–51 (x264 range); max_height 0 = source.
+    ConfigSpec("plex_transcode_hw", "str", "plex", "plex_transcode_hw"),
+    ConfigSpec("plex_transcode_preset", "str", "plex", "plex_transcode_preset"),
+    ConfigSpec("plex_transcode_crf", "int", "plex", "plex_transcode_crf", min=0, max=51),
+    ConfigSpec(
+        "plex_transcode_max_height", "int", "plex", "plex_transcode_max_height", min=0, max=4320
+    ),
     # NOTE: plex_watch_sync_interval_min is a config.py default read by the watch-sync scheduler job
     # (scheduler.py); it is intentionally NOT a runtime admin knob, so it stays out of SPECS.
     # --- TMDB enrichment (E5 S2; optional) — the API key is the only secret ---

backend/app/utils.py

@@ -22,6 +22,39 @@ def valid_email(value: str | None) -> bool:
     return bool(value and _EMAIL_RE.match(value))
 
 
+# Gmail (and its googlemail.com alias) delivers to one mailbox regardless of dots in the local part
+# and of any `+tag`; nobody else is guaranteed to. So the canonical form below strips those for
+# Gmail only, and merely lowercases everything else.
+_GMAIL_DOMAINS = {"gmail.com", "googlemail.com"}
+
+
+def canonical_email(value: str | None) -> str:
+    """The form used to decide whether two addresses are the SAME MAILBOX. Never used for sending —
+    mail always goes to the address as the user typed it.
+
+    Why this exists (observed on prod, 2026-09-03): someone registered as `npeter83.temu@gmail.com`
+    and was approved, but Google's OAuth `email` claim came back as the account's stored primary,
+    `npeter83temu@gmail.com`. The invite gate only lowercased, found no approved row for that literal
+    string, and turned an approved user's sign-in into a silent SECOND access request — plus a second
+    User row. The `+tag` case is worse and fails every time: a Google account cannot contain `+`, so
+    OAuth can only ever return the base address, meaning anyone who registers with
+    `user+siftlode@gmail.com` (a common throwaway habit) is guaranteed to be denied after approval.
+
+    Scope is deliberately narrow. The dot rule does NOT hold for Google Workspace custom domains
+    unless the admin turned it on, and dots are significant on most providers, so anything outside
+    gmail.com/googlemail.com is only lowercased. Approving one Gmail spelling always did mean
+    approving that mailbox, so collapsing them is the honest reading of an invite, not a widening
+    of it.
+    """
+    email = (value or "").strip().lower()
+    local, sep, domain = email.partition("@")
+    if not sep or domain not in _GMAIL_DOMAINS:
+        return email
+    local = local.partition("+")[0].replace(".", "")
+    # Normalise the alias domain too, so googlemail and gmail spellings meet.
+    return f"{local}@gmail.com" if local else email
+
+
 def now_utc() -> datetime:
     """Current time as a timezone-aware UTC datetime."""
     return datetime.now(timezone.utc)

backend/requirements.lock

@@ -43,6 +43,7 @@ pydantic-settings==2.15.0
 pydantic==2.13.4
 pydantic_core==2.46.4
 python-dotenv==1.2.3
+python-multipart==0.0.32
 requests==2.34.2
 starlette==1.6.0
 typing-inspection==0.4.4

backend/requirements.txt

@@ -1,4 +1,7 @@
 fastapi>=0.115,<1.0
+# Multipart form parsing — required by Starlette/FastAPI to accept file uploads (UploadFile/Form).
+# The download center's local-file Upload (E7) is the only multipart endpoint in the app.
+python-multipart>=0.0.9,<1.0
 uvicorn[standard]>=0.30,<1.0
 sqlalchemy>=2.0,<2.1
 psycopg[binary]>=3.2,<4.0

backend/tests/conftest.py

@@ -189,3 +189,24 @@ def as_user(db, override_dep, _configured):
         return TestClient(app, headers={"x-test-user": str(user.id)})
 
     return _as
+
+
+@pytest.fixture(autouse=True)
+def _reset_rate_limiters():
+    """Every RateLimiter is a module-level singleton keyed by client IP, and TestClient always
+    presents the same host — so without this the whole suite's login/register attempts pool into one
+    300s window and, past the cap, some unrelated test starts failing with a 429 depending on order.
+    Cleared before each test; a test that wants to exercise throttling can still exhaust one itself.
+
+    Sweeps every loaded `app.*` module rather than a hand-kept list, so a limiter added in a new
+    module is covered the day it lands instead of silently pooling until something fails."""
+    import sys
+
+    from app.ratelimit import RateLimiter
+
+    for name, mod in list(sys.modules.items()):
+        if name != "app" and not name.startswith("app."):
+            continue
+        for obj in vars(mod).values():
+            if isinstance(obj, RateLimiter):
+                obj.reset()

backend/tests/test_admin_invites.py

@@ -0,0 +1,170 @@
+"""Deleting a whitelist / access-request entry (admin).
+
+Deny records an auditable decision and keeps the row; delete forgets the address outright, for an
+approval added by mistake or one that is no longer wanted. Neither stops the person asking again —
+`upsert_pending_invite` reopens a denied row as pending, and a deleted one comes back as a fresh
+request. The one hard rule is that an entry backed by an account is NOT deletable here: this row is
+that account's approval gate, and orphaning it would strand someone who could then neither sign in
+nor be approved.
+"""
+
+from sqlalchemy import select
+
+from app.models import Invite, User
+
+
+def _invites(client):
+    r = client.get("/api/admin/invites")
+    assert r.status_code == 200
+    return {i["email"]: i for i in r.json()}
+
+
+def test_admin_deletes_a_whitelist_entry_that_never_became_an_account(db, make_user, as_user):
+    admin = make_user(email="admin@example.com", role="admin")
+    db.add(Invite(email="mistake@example.com", status="approved", decided_by=admin.email))
+    db.commit()
+    client = as_user(admin)
+    listed = _invites(client)["mistake@example.com"]
+    assert listed["has_account"] is False  # drives the delete affordance in the UI
+
+    r = client.delete(f"/api/admin/invites/{listed['id']}")
+
+    assert r.status_code == 200 and r.json()["deleted"] == listed["id"]
+    db.expire_all()
+    assert (
+        db.execute(select(Invite).where(Invite.email == "mistake@example.com")).scalar_one_or_none()
+        is None
+    )
+
+
+def test_deleting_an_entry_that_has_an_account_is_refused(db, make_user, as_user):
+    # The guard that matters: this row is what is_allowed() reads, so deleting it would revoke the
+    # user's access without touching the account or saying so.
+    admin = make_user(email="admin@example.com", role="admin")
+    member = make_user(email="member@example.com")
+    db.add(Invite(email=member.email, status="approved", decided_by=admin.email))
+    db.commit()
+    client = as_user(admin)
+    listed = _invites(client)[member.email]
+    assert listed["has_account"] is True
+
+    r = client.delete(f"/api/admin/invites/{listed['id']}")
+
+    assert r.status_code == 409
+    db.expire_all()
+    assert (
+        db.execute(select(Invite).where(Invite.email == member.email)).scalar_one_or_none()
+        is not None
+    )
+
+
+def test_a_pending_request_from_a_registration_is_not_deletable(db, make_user, as_user):
+    # The shape the ordinary sign-up produces: _register_account writes the User (inactive) AND the
+    # pending Invite together. The invite is that account's approval gate, so deleting it would
+    # strand the person — they could neither sign in nor be approved, and re-registering is a silent
+    # no-op. Managed from Users & roles instead, which is what the UI and the 409 both say.
+    admin = make_user(email="admin@example.com", role="admin")
+    make_user(email="signup@example.com", is_active=False, email_verified=False)
+    db.add(Invite(email="signup@example.com", status="pending"))
+    db.commit()
+    client = as_user(admin)
+    listed = _invites(client)["signup@example.com"]
+    assert listed["has_account"] is True  # the UI shows a disabled control, not a missing one
+
+    r = client.delete(f"/api/admin/invites/{listed['id']}")
+
+    assert r.status_code == 409
+    db.expire_all()
+    assert (
+        db.execute(select(Invite).where(Invite.email == "signup@example.com")).scalar_one_or_none()
+        is not None
+    )
+
+
+def test_deleting_an_env_allow_listed_address_reports_that_it_kept_access(
+    db, make_user, as_user, monkeypatch
+):
+    # Removing the row is NOT always a revoke: is_allowed falls back to the env bootstrap lists once
+    # no invite exists. The admin has to be told, or they think they removed access and did not.
+    from app.config import settings
+
+    # Patch the raw env field, not the derived property: that keeps the split/strip/lower parsing
+    # under test, and matches how the rest of the suite stubs settings.
+    monkeypatch.setattr(settings, "allowed_emails", " OPS@Example.com , someone@else.test ")
+    admin = make_user(email="admin@example.com", role="admin")
+    db.add(Invite(email="ops@example.com", status="approved", decided_by=admin.email))
+    db.commit()
+    client = as_user(admin)
+    listed = _invites(client)["ops@example.com"]
+    # The LIST carries it too, so the confirm dialog can warn before the delete happens.
+    assert listed["still_allowed_by_env"] is True
+
+    r = client.delete(f"/api/admin/invites/{listed['id']}")
+
+    assert r.status_code == 200
+    assert r.json()["still_allowed_by_env"] is True
+
+
+def test_an_admin_emails_address_is_also_reported(db, make_user, as_user, monkeypatch):
+    # ADMIN_EMAILS is the sharper case: deleting the row not only keeps access, the next Google
+    # sign-in re-promotes the address to admin.
+    from app.config import settings
+
+    monkeypatch.setattr(settings, "admin_emails", "boss@example.com")
+    admin = make_user(email="admin@example.com", role="admin")
+    db.add(Invite(email="boss@example.com", status="approved", decided_by=admin.email))
+    db.commit()
+    client = as_user(admin)
+
+    assert _invites(client)["boss@example.com"]["still_allowed_by_env"] is True
+
+
+def test_deleting_a_pending_request_forgets_it(db, make_user, as_user):
+    # A pending row is deletable too — "drop this without recording a decision" is a different
+    # choice from Deny, which stores a decision (status, decided_by) and mails the requester.
+    admin = make_user(email="admin@example.com", role="admin")
+    db.add(Invite(email="asker@example.com", status="pending"))
+    db.commit()
+    client = as_user(admin)
+
+    r = client.delete(f"/api/admin/invites/{_invites(client)['asker@example.com']['id']}")
+
+    assert r.status_code == 200
+    assert r.json()["still_allowed_by_env"] is False  # nothing in the env allow-lists
+    assert "asker@example.com" not in _invites(client)
+
+
+def test_deleting_a_missing_invite_is_404(db, make_user, as_user):
+    admin = make_user(email="admin@example.com", role="admin")
+    assert as_user(admin).delete("/api/admin/invites/9999").status_code == 404
+
+
+def test_a_regular_user_cannot_delete_an_invite(db, make_user, as_user):
+    make_user(email="admin@example.com", role="admin")
+    plain = make_user(email="plain@example.com")
+    db.add(Invite(email="mistake@example.com", status="approved"))
+    db.commit()
+    inv_id = db.execute(select(Invite.id).where(Invite.email == "mistake@example.com")).scalar_one()
+
+    assert as_user(plain).delete(f"/api/admin/invites/{inv_id}").status_code == 403
+
+    db.expire_all()
+    assert db.get(Invite, inv_id) is not None
+
+
+def test_deleting_the_user_also_clears_the_way_to_re_invite(db, make_user, as_user):
+    # The refusal above tells the admin to delete the account instead; purge_user takes the invite
+    # with it, so the address really is forgotten and a fresh request starts over as pending.
+    admin = make_user(email="admin@example.com", role="admin")
+    member = make_user(email="member@example.com")
+    db.add(Invite(email=member.email, status="approved", decided_by=admin.email))
+    db.commit()
+    client = as_user(admin)
+
+    assert client.delete(f"/api/admin/users/{member.id}").status_code == 200
+
+    db.expire_all()
+    assert db.execute(select(User).where(User.email == member.email)).scalar_one_or_none() is None
+    assert (
+        db.execute(select(Invite).where(Invite.email == member.email)).scalar_one_or_none() is None
+    )

backend/tests/test_admin_pending_access.py

@@ -0,0 +1,203 @@
+"""The admin lifeline for a sign-up that is stuck outside (E9.5 S5, roadmap UX-25), DB-lane.
+
+Approve an address BEFORE the person registers and their sign-up produces no queue row at all —
+`_decide` only takes a still-pending invite — so the Access-requests screen stayed empty while they
+sat locked out, and the badge read zero. The only working move was re-typing the address into the
+whitelist box, which nobody would guess.
+
+Two earlier attempts at this were reverted after review, and both moved AUTHORITY rather than
+visibility: auto-activating on registration, and reopening the approved invite to pending. So the
+tests here pin the boundary as much as the feature — an admin click, gated on an address that is
+already allowed, and nothing an unauthenticated caller can reach.
+"""
+
+from sqlalchemy import select
+
+from app.models import AuditLog, AuthToken, Invite, User
+
+_PW = "correct horse battery"
+
+
+def _pending_access(client):
+    r = client.get("/api/admin/pending-access")
+    assert r.status_code == 200
+    return {u["email"]: u for u in r.json()}
+
+
+def _stuck_registrant(db, make_user, admin):
+    """The UX-25 shape: the admin approved the address first, the account arrived afterwards."""
+    db.add(Invite(email="later@example.com", status="approved", decided_by=admin.email))
+    db.commit()
+    return make_user(email="later@example.com", password=_PW, is_active=False)
+
+
+def test_a_pre_approved_registrant_is_listed_and_offers_activation(db, make_user, as_user):
+    admin = make_user(email="admin@example.com", role="admin")
+    _stuck_registrant(db, make_user, admin)
+
+    row = _pending_access(as_user(admin))["later@example.com"]
+
+    assert row["is_active"] is False
+    assert (
+        row["can_activate"] is True
+    )  # the address is already allowed — the click just finishes it
+
+
+def test_an_ordinary_registrant_awaiting_a_decision_is_not_listed_twice(db, make_user, as_user):
+    # They already have a pending invite with Approve on it in the queue above, and their address is
+    # not allowed YET — the decision is the queue's to own. Caught in UAT on 2026-09-05: an earlier
+    # filter keyed on "unconfirmed" put every fresh registration in both lists at once.
+    admin = make_user(email="admin@example.com", role="admin")
+    db.add(Invite(email="normal@example.com", status="pending"))
+    db.commit()
+    make_user(email="normal@example.com", password=_PW, is_active=False)
+
+    assert "normal@example.com" not in _pending_access(as_user(admin))
+
+
+def test_a_fresh_registration_stays_in_the_queue_and_out_of_this_list(db, make_user, as_user):
+    # The realistic version of the case above: a brand-new sign-up is inactive AND unconfirmed. It
+    # still belongs only to the queue — the admin's next act is the decision, not a re-send.
+    admin = make_user(email="admin@example.com", role="admin")
+    db.add(Invite(email="fresh@example.com", status="pending"))
+    db.commit()
+    make_user(email="fresh@example.com", password=_PW, is_active=False, email_verified=False)
+
+    assert "fresh@example.com" not in _pending_access(as_user(admin))
+
+
+def test_activating_lets_them_in_and_is_recorded(db, make_user, as_user):
+    admin = make_user(email="admin@example.com", role="admin")
+    stuck = _stuck_registrant(db, make_user, admin)
+
+    r = as_user(admin).post(f"/api/admin/users/{stuck.id}/activate")
+
+    assert r.status_code == 200 and r.json()["is_active"] is True
+    db.expire_all()
+    assert db.get(User, stuck.id).is_active is True
+    actions = db.execute(select(AuditLog.action)).scalars().all()
+    assert (
+        "user_activate" in actions
+    )  # the admin acted on someone's access; it is not a silent read
+
+
+def test_activating_an_address_that_is_not_allowed_is_refused(db, make_user, as_user):
+    # The guard that keeps this button from manufacturing an inconsistent account: password sign-in
+    # only checks is_active and would let them in, while their Google sign-in would be turned away
+    # and silently reopened as a fresh access request. Whitelisting is the move that says "let them
+    # in"; this one only finishes a decision already made.
+    admin = make_user(email="admin@example.com", role="admin")
+    nobody = make_user(email="nobody@example.com", password=_PW, is_active=False)
+
+    r = as_user(admin).post(f"/api/admin/users/{nobody.id}/activate")
+
+    assert r.status_code == 409
+    assert r.json()["detail"]["reason"] == "not_allowed"
+    db.expire_all()
+    assert db.get(User, nobody.id).is_active is False
+
+
+def test_activating_twice_is_not_an_error(db, make_user, as_user):
+    admin = make_user(email="admin@example.com", role="admin")
+    stuck = _stuck_registrant(db, make_user, admin)
+    client = as_user(admin)
+
+    assert client.post(f"/api/admin/users/{stuck.id}/activate").status_code == 200
+    assert client.post(f"/api/admin/users/{stuck.id}/activate").status_code == 200
+
+
+def test_a_suspended_account_is_not_offered_as_stuck(db, make_user, as_user):
+    # It cannot sign in either, but that is a decision already made — not a person waiting on one.
+    admin = make_user(email="admin@example.com", role="admin")
+    db.add(Invite(email="banned@example.com", status="approved", decided_by=admin.email))
+    db.commit()
+    make_user(email="banned@example.com", password=_PW, is_active=False, is_suspended=True)
+
+    assert "banned@example.com" not in _pending_access(as_user(admin))
+
+
+# --- the confirmation resend ---------------------------------------------------------------------
+
+
+def test_an_unconfirmed_account_is_listed_and_can_be_sent_a_fresh_link(
+    db, make_user, as_user, monkeypatch
+):
+    from app.routes import admin as admin_routes
+    from app.routes import auth as auth_routes
+
+    monkeypatch.setattr(admin_routes.email_mod, "email_enabled", lambda db=None: True)
+    sent: list[tuple[str, str]] = []
+    monkeypatch.setattr(
+        auth_routes.email_mod,
+        "send_verify_email",
+        lambda to, lang, link, **kw: sent.append((to, link)) is None,
+    )
+    admin = make_user(email="admin@example.com", role="admin")
+    # Active but unconfirmed — a real state since E9.5 S1 made the two gates order-independent. It is
+    # not the admin's to decide, but the mail may simply never have arrived, so it is theirs to help
+    # with. The approved invite is what puts them on this screen at all: the list is "the address may
+    # sign in, this account still can't", so an undecided request stays with the queue that owns it.
+    db.add(Invite(email="unconfirmed@example.com", status="approved", decided_by=admin.email))
+    db.commit()
+    u = make_user(email="unconfirmed@example.com", password=_PW, email_verified=False)
+
+    assert "unconfirmed@example.com" in _pending_access(as_user(admin))
+    r = as_user(admin).post(f"/api/admin/users/{u.id}/resend-verification")
+
+    assert r.status_code == 200 and r.json()["email"] == "unconfirmed@example.com"
+    assert [to for to, _ in sent] == ["unconfirmed@example.com"]
+    tokens = db.execute(select(AuthToken).where(AuthToken.user_id == u.id)).scalars().all()
+    assert [t.kind for t in tokens] == ["verify"]
+
+
+def test_the_resend_says_so_when_the_instance_cannot_send_mail(db, make_user, as_user, monkeypatch):
+    from app.routes import admin as admin_routes
+
+    monkeypatch.setattr(admin_routes.email_mod, "email_enabled", lambda db=None: False)
+    admin = make_user(email="admin@example.com", role="admin")
+    u = make_user(email="unconfirmed@example.com", password=_PW, email_verified=False)
+
+    r = as_user(admin).post(f"/api/admin/users/{u.id}/resend-verification")
+
+    # Mail is fail-soft everywhere else, which is exactly what left the 0.78.5 sign-ups with nothing
+    # to fall back on. An admin pressing a button gets the failure, not a success toast.
+    assert r.status_code == 409 and r.json()["detail"]["reason"] == "email_off"
+
+
+def test_resending_to_an_already_confirmed_account_is_refused(db, make_user, as_user):
+    admin = make_user(email="admin@example.com", role="admin")
+    u = make_user(email="fine@example.com", password=_PW)
+
+    r = as_user(admin).post(f"/api/admin/users/{u.id}/resend-verification")
+
+    assert r.status_code == 409 and r.json()["detail"]["reason"] == "not_applicable"
+
+
+# --- the badge -----------------------------------------------------------------------------------
+
+
+def test_the_badge_counts_stuck_sign_ups_but_not_ones_the_queue_already_shows(
+    db, make_user, client
+):
+    # Signed in for real, not via the as_user override: /api/me resolves its user through
+    # optional_current_user, which that override does not cover (see test_me_email_flag).
+    admin = make_user(email="admin@example.com", password=_PW, role="admin")
+    _stuck_registrant(db, make_user, admin)  # approved first → counts
+    db.add(Invite(email="normal@example.com", status="pending"))  # already in the queue → doesn't
+    db.commit()
+    make_user(email="normal@example.com", password=_PW, is_active=False)
+    make_user(email="unconfirmed@example.com", password=_PW, email_verified=False)  # not ours
+
+    assert (
+        client.post(
+            "/auth/password-login", json={"email": admin.email, "password": _PW}
+        ).status_code
+        == 200
+    )
+    me = client.get("/api/me").json()
+    assert me["authenticated"] is True
+
+    # An unconfirmed account waits on its OWNER, not on the admin — listing it is help, badging it
+    # would be nagging about something the admin did not cause.
+    assert me["pending_activations"] == 1
+    assert me["pending_invites"] == 1  # unchanged meaning: still just the undecided requests

backend/tests/test_auth_session.py

@@ -97,28 +97,85 @@ def test_reset_confirm_is_single_use_and_kills_existing_sessions(client, make_us
     assert replay.status_code == 400
 
 
-def test_activating_an_unverified_account_drops_its_preset_password(db, make_user):
-    # SEC-10 (account pre-emption): an attacker registers victim@x with a password before the approved
-    # owner arrives. The address was never verified, so admin approval must NOT hand that pre-set
-    # password a working login — it is dropped and any session it minted is revoked.
+def test_approving_an_unverified_account_keeps_its_password(db, make_user):
+    # E9.5 S1, inverting an earlier rule. Approval used to drop a password set while the email was
+    # unverified (SEC-10, account pre-emption). It was dropped because it destroyed the password a
+    # legitimate registrant had just chosen, in what is the NORMAL ordering — the admin decides
+    # before the user reads their mail — making "your password was cleared for security" the default
+    # experience.
+    #
+    # S1 ALSO argued the revoke was redundant, because password_login refuses an unverified account
+    # before it reads is_active. The epic's closing review refuted that: the gate holds only while
+    # the address is unverified, and S6's approval mail exists to get the real owner to end that
+    # state. Do not restore that reasoning from this comment — the residual is SEC-16, and round 2
+    # of the review tried and reverted a guard for it (see test_review_round.py).
     from app.routes.admin import _activate_user_by_email
 
-    victim = make_user(
-        email="victim@example.com",
-        password="attacker-chosen",
+    user = make_user(
+        email="approved-first@example.com",
+        password="chosen at registration",
         email_verified=False,
         is_active=False,
     )
-    epoch0 = victim.session_epoch or 0
-    _activate_user_by_email(db, "victim@example.com")
-    assert victim.is_active is True
-    assert victim.password_hash is None
-    assert (victim.session_epoch or 0) == epoch0 + 1
+    epoch0 = user.session_epoch or 0
+
+    _activate_user_by_email(db, "approved-first@example.com")
+
+    assert user.is_active is True
+    assert user.password_hash is not None
+    assert user.password_revoked_at is None
+    assert (user.session_epoch or 0) == epoch0  # nothing to revoke, so no epoch bump either
+
+
+def test_an_approved_but_unverified_account_still_cannot_sign_in(client, make_user):
+    # The gate that stops a pre-emptor BEFORE the address is confirmed, whatever the admin decided.
+    # It is not the whole story — confirming the address opens it, which is SEC-16 — but it is the
+    # invariant this test owns, and a change that let an unverified account sign in would be a
+    # straightforwardly worse bug than the residual.
+    make_user(
+        email="notyet@example.com",
+        password="attacker-chosen",
+        email_verified=False,
+        is_active=True,
+    )
+
+    r = _login(client, "notyet@example.com", "attacker-chosen")
+
+    assert r.status_code == 403
+    assert r.json()["detail"]["reason"] == "email_unverified"
+
+
+def test_verifying_afterwards_lets_the_original_password_in(client, db, make_user):
+    # The payoff for the legitimate registrant: the password chosen at registration still works once
+    # the mailbox is proven — no "your password was cleared for security" detour, no reset round-trip.
+    from app.routes.auth import _issue_token
+
+    user = make_user(
+        email="ordering@example.com",
+        password="chosen at registration",
+        email_verified=False,
+        is_active=False,
+    )
+    from app.routes.admin import _activate_user_by_email
+
+    _activate_user_by_email(db, "ordering@example.com")  # admin decides FIRST — the common ordering
+    raw = _issue_token(db, user, "verify", timedelta(hours=1))
+    db.commit()
+
+    verified = client.post("/auth/verify", json={"token": raw})
+
+    assert verified.status_code == 200
+    assert verified.json() == {
+        "ok": True,
+        "password_reset_required": False,
+        "email": "ordering@example.com",
+    }
+    assert _login(client, "ordering@example.com", "chosen at registration").status_code == 200
 
 
 def test_activating_a_verified_account_keeps_its_password(db, make_user):
-    # A legit account whose email IS verified (e.g. a no-SMTP registration) keeps its password on
-    # approval — the guard must not break the normal flow.
+    # The no-SMTP shape: registration marks such an account verified up front, so it was never in
+    # scope for the SEC-10 guard even before E9.5 S1. Kept as the other half of the pair.
     from app.routes.admin import _activate_user_by_email
 
     user = make_user(
@@ -127,3 +184,374 @@ def test_activating_a_verified_account_keeps_its_password(db, make_user):
     _activate_user_by_email(db, "legit@example.com")
     assert user.is_active is True
     assert user.password_hash is not None
+
+
+def _register_and_fetch(db, email: str):
+    """Run the /register background worker, then read the users/invites rows back through a FRESH
+    query. The worker owns its own session, so anything it failed to commit is simply not there."""
+    from sqlalchemy import select as _select
+
+    from app.models import Invite, User
+    from app.routes.auth import _register_account
+
+    _register_account(email, _PW)
+    db.expire_all()
+    user = db.execute(_select(User).where(User.email == email)).scalar_one_or_none()
+    invite = db.execute(_select(Invite).where(Invite.email == email)).scalar_one_or_none()
+    return user, invite
+
+
+def _no_smtp(monkeypatch):
+    """Put the worker on the no-SMTP path and capture the admin notice instead of sending it."""
+    from app.routes import auth as auth_mod
+
+    notified: list[str] = []
+    monkeypatch.setattr(auth_mod.email_mod, "email_enabled", lambda: False)
+    monkeypatch.setattr(
+        auth_mod.email_mod,
+        "send_admin_new_request",
+        lambda admins, lang, to: notified.append(to) or True,
+    )
+    return notified
+
+
+def test_registration_of_a_pre_approved_email_persists_the_account_without_smtp(
+    db, make_user, monkeypatch
+):
+    # THE regression. An admin whitelists an address, the person registers, and the account silently
+    # never existed: upsert_pending_invite leaves an already-approved row alone and returns WITHOUT
+    # committing, and the only other commit on this path (_issue_token) is gated on SMTP — so with no
+    # working mail the flushed user was rolled back at session close. The sign-up answered "ok",
+    # created nothing, and re-registering did the same again.
+    from app.models import Invite
+
+    notified = _no_smtp(monkeypatch)
+    make_user(email="admin@example.com", role="admin")
+    db.add(Invite(email="roland@example.com", status="approved", decided_by="admin@example.com"))
+    db.commit()
+
+    user, invite = _register_and_fetch(db, "roland@example.com")
+
+    assert user is not None, "pre-approved registration was rolled back — the account is gone"
+    assert user.password_hash is not None
+    assert user.email_verified is True  # no SMTP => ownership can't be proven by link
+    assert (
+        user.is_active is False
+    )  # approval is bound to the account by an admin, not by signing up
+    # The admin's standing decision is left exactly as it was — is_allowed() still reads "approved",
+    # so their Google sign-in keeps working and an anonymous sign-up cannot revoke access.
+    assert invite.status == "approved"
+    assert invite.decided_by == "admin@example.com"
+    # The notify path still fires for an already-approved address — nothing lands in the queue, so
+    # it is the only announcement there is. (Whether it is DELIVERED is separate: on a real no-SMTP
+    # instance `_send` drops it, which is the open half of the problem, roadmap UX-25.)
+    assert notified == ["roland@example.com"]
+
+
+def test_registration_with_an_already_pending_request_persists_the_account(
+    db, make_user, monkeypatch
+):
+    # The same rollback, reached the other way: someone uses Request access, then registers before
+    # the admin has decided. upsert_pending_invite leaves the pending row alone and does not commit.
+    from app.models import Invite
+
+    notified = _no_smtp(monkeypatch)
+    make_user(email="admin@example.com", role="admin")
+    db.add(Invite(email="pia@example.com", status="pending"))
+    db.commit()
+
+    user, invite = _register_and_fetch(db, "pia@example.com")
+
+    assert user is not None, "registration was rolled back — the account is gone"
+    assert user.is_active is False
+    assert invite.status == "pending"
+    assert notified == ["pia@example.com"]
+
+
+def test_an_admin_can_activate_a_pre_approved_registrant(db, monkeypatch):
+    # The recovery path for the account above, pinned so it cannot quietly break: re-entering the
+    # address in the Access-requests whitelist box (POST /api/admin/invites) runs
+    # _activate_user_by_email.
+    from app.models import Invite
+    from app.routes.admin import _activate_user_by_email
+
+    _no_smtp(monkeypatch)
+    db.add(Invite(email="roland@example.com", status="approved", decided_by="admin@example.com"))
+    db.commit()
+    user, _ = _register_and_fetch(db, "roland@example.com")
+
+    _activate_user_by_email(db, "roland@example.com")
+
+    db.expire_all()
+    assert user.is_active is True
+    assert user.password_hash is not None  # approval never touches the password (E9.5 S1)
+
+
+def test_registration_of_an_unknown_email_still_persists_account_and_pending_invite(
+    db, make_user, monkeypatch
+):
+    # Guard, not a regression test: this branch always worked (upsert INSERTs the invite and commits
+    # the same transaction). It must keep working — and it is the case that DOES notify the admin.
+    notified = _no_smtp(monkeypatch)
+    make_user(email="admin@example.com", role="admin")
+
+    user, invite = _register_and_fetch(db, "stranger@example.com")
+
+    assert user is not None
+    assert user.is_active is False
+    assert invite is not None and invite.status == "pending"
+    assert notified == ["stranger@example.com"]
+
+
+def test_registration_of_a_previously_denied_email_revives_the_request(db, make_user, monkeypatch):
+    # Guard: a denied person may ask again — the invite flips back to pending (and commits) so the
+    # admin sees a fresh request. The stale decision must not leak into the new account's state.
+    from app.models import Invite
+
+    notified = _no_smtp(monkeypatch)
+    make_user(email="admin@example.com", role="admin")
+    db.add(Invite(email="denis@example.com", status="denied", decided_by="admin@example.com"))
+    db.commit()
+
+    user, invite = _register_and_fetch(db, "denis@example.com")
+
+    assert user is not None
+    assert user.is_active is False
+    assert invite.status == "pending"
+    assert invite.decided_at is None and invite.decided_by is None
+    assert notified == ["denis@example.com"]
+
+
+def test_registration_of_a_pre_approved_email_persists_the_account_with_smtp(db, monkeypatch):
+    # Guard, not a regression test: with SMTP on, _issue_token's own commit already persisted the
+    # user, so this branch was never broken and must stay unbroken.
+    from app.models import Invite
+    from app.routes import auth as auth_mod
+
+    sent: list[str] = []
+    monkeypatch.setattr(auth_mod.email_mod, "email_enabled", lambda: True)
+    monkeypatch.setattr(
+        auth_mod.email_mod, "send_verify_email", lambda to, lang, link, **kw: sent.append(to)
+    )
+    monkeypatch.setattr(auth_mod.email_mod, "send_admin_new_request", lambda admins, lang, to: True)
+    db.add(Invite(email="rita@example.com", status="approved", decided_by="admin@example.com"))
+    db.commit()
+
+    user, invite = _register_and_fetch(db, "rita@example.com")
+
+    assert user is not None
+    assert user.email_verified is False  # must confirm the address
+    assert user.is_active is False
+    assert invite.status == "approved"
+    assert sent == ["rita@example.com"]
+
+
+def test_verifying_an_email_never_grants_access_on_its_own(client, db, make_user):
+    # Verification attests the address; it does not decide access. The two gates stay separate.
+    from app.models import Invite
+    from app.routes.auth import _issue_token
+
+    user = make_user(email="rita@example.com", password=_PW, email_verified=False, is_active=False)
+    db.add(Invite(email="rita@example.com", status="approved", decided_by="admin@example.com"))
+    db.commit()
+    raw = _issue_token(db, user, "verify", timedelta(hours=1))
+
+    assert client.post("/auth/verify", json={"token": raw}).status_code == 200
+
+    db.expire_all()
+    assert user.email_verified is True
+    assert user.is_active is False
+    assert _login(client, "rita@example.com", _PW).status_code == 403
+
+
+def test_register_route_creates_the_account_end_to_end(client, db, monkeypatch):
+    # The tests above call _register_account directly, so nothing covered the ROUTE: its
+    # allow_registration gate, its rate limiter and the background.add_task wiring that makes the
+    # whole flow reachable at all. TestClient runs BackgroundTasks after the response, so a single
+    # POST exercises the real path end to end.
+    from sqlalchemy import select as _select
+
+    from app.models import User
+
+    _no_smtp(monkeypatch)
+
+    r = client.post("/auth/register", json={"email": "newbie@example.com", "password": _PW})
+
+    assert r.status_code == 200 and r.json() == {"status": "ok"}
+    db.expire_all()
+    user = db.execute(_select(User).where(User.email == "newbie@example.com")).scalar_one_or_none()
+    assert user is not None, "POST /auth/register answered ok but created nothing"
+    assert user.password_hash is not None
+
+
+def test_register_route_is_refused_when_registration_is_closed(client, db, monkeypatch):
+    # The gate is an explicit 403 with nothing created — not a uniform "ok" that silently drops it.
+    from sqlalchemy import select as _select
+
+    from app import sysconfig
+    from app.models import User
+
+    _no_smtp(monkeypatch)
+    sysconfig.set_value(db, "allow_registration", False)
+
+    r = client.post("/auth/register", json={"email": "closed@example.com", "password": _PW})
+
+    assert r.status_code == 403
+    db.expire_all()
+    assert (
+        db.execute(_select(User).where(User.email == "closed@example.com")).scalar_one_or_none()
+        is None
+    )
+
+
+# --- SEC-10 lockout: a revoked preset password must stay RECOVERABLE ---------------------------
+#
+# Regression pack for the prod incident of 2026-09-02. An account registered with a password, then
+# stripped of it by the SEC-10 guard, ended up with password_hash = NULL. That is also what a
+# Google-only account looks like, and reset eligibility keyed off `password_hash` alone — so the
+# account could neither sign in (no password) nor obtain a reset link, and every response on the way
+# was a deliberately uniform "ok"/401. `password_revoked_at` is the trace that tells the two apart;
+# these pin each step of the way back in.
+#
+# E9.5 S1 removed the admin-approval caller, so Google adoption is the only path that still produces
+# this state — plus every account stripped on prod before that change, which is why the whole recovery
+# route below must keep working. These tests manufacture the state through the surviving producer.
+
+
+def _revoke_as_google_adoption(db, user) -> None:
+    """Put an account into the SEC-10-revoked state the way the ONLY remaining producer does: the
+    Google callback adopting an account whose email was never verified."""
+    from app.routes.auth import revoke_preset_password_if_unverified
+
+    revoke_preset_password_if_unverified(user)
+    db.commit()
+
+
+def _capture_reset_links(monkeypatch) -> list[str]:
+    """Patch the reset mailer and collect the recipients it is asked to write to."""
+    from app.routes import auth as auth_mod
+
+    sent: list[str] = []
+    monkeypatch.setattr(
+        auth_mod.email_mod, "send_password_reset", lambda to, lang, link: sent.append(to)
+    )
+    return sent
+
+
+def test_the_google_adoption_revoke_stamps_password_revoked_at(db, make_user):
+    # The guard still fires where it earns its keep: the real owner has just proven ownership through
+    # Google, so a password set on the address while it was unverified must not survive.
+    victim = make_user(
+        email="stamped@example.com",
+        password="attacker-chosen",
+        email_verified=False,
+        is_active=False,
+    )
+    assert victim.password_revoked_at is None
+    epoch0 = victim.session_epoch or 0
+
+    _revoke_as_google_adoption(db, victim)
+
+    assert victim.password_hash is None
+    assert victim.password_revoked_at is not None  # …so the reset flow can tell it HAD a password
+    assert (victim.session_epoch or 0) == epoch0 + 1  # any session that password minted is killed
+
+
+def test_an_account_whose_password_was_revoked_can_still_get_a_reset_link(
+    db, make_user, monkeypatch
+):
+    # THE lockout bug: without the stamp this sent nothing, and the account was unrecoverable.
+    from app.routes.auth import _send_reset_if_eligible
+
+    victim = make_user(
+        email="lockedout@example.com",
+        password="chosen at registration",
+        email_verified=False,
+        is_active=False,
+    )
+    _revoke_as_google_adoption(db, victim)
+    sent = _capture_reset_links(monkeypatch)
+
+    _send_reset_if_eligible("lockedout@example.com")
+
+    assert sent == ["lockedout@example.com"]
+
+
+def test_a_google_only_account_is_still_not_reset_eligible(db, make_user, monkeypatch):
+    # The other side of the rule: an account that NEVER had a password gets no reset link — its owner
+    # adds one from Settings while signed in (/auth/set-password), which proves identity by session.
+    from app.routes.auth import _send_reset_if_eligible
+
+    make_user(email="googler@example.com", password=None, google_sub="sub-123")
+    sent = _capture_reset_links(monkeypatch)
+
+    _send_reset_if_eligible("googler@example.com")
+
+    assert sent == []
+
+
+def test_completing_a_reset_clears_the_revocation_stamp(client, db, make_user):
+    from app.routes.auth import _issue_token
+
+    user = make_user(
+        email="recovered@example.com",
+        password="chosen at registration",
+        email_verified=False,
+        is_active=True,  # already approved; reset-confirm verifies the email but never activates
+    )
+    _revoke_as_google_adoption(db, user)
+    raw = _issue_token(db, user, "reset", timedelta(hours=1))
+    db.commit()
+
+    ok = client.post(
+        "/auth/password-reset/confirm", json={"token": raw, "password": "a brand new one"}
+    )
+
+    assert ok.status_code == 200
+    db.expire_all()
+    assert user.password_hash is not None
+    assert user.password_revoked_at is None  # spent — not a permanently reset-eligible account
+    assert _login(client, "recovered@example.com", "a brand new one").status_code == 200
+
+
+def test_verify_tells_a_revoked_account_that_it_needs_a_new_password(client, db, make_user):
+    # The banner's input. Saying so leaks nothing: the caller just proved mailbox control by holding a
+    # valid single-use verify token. Without it the user meets only the uniform "Invalid email or
+    # password" and has no way to learn why the password they chose stopped working.
+    from app.routes.auth import _issue_token
+
+    user = make_user(
+        email="needspw@example.com",
+        password="chosen at registration",
+        email_verified=False,
+        is_active=False,
+    )
+    _revoke_as_google_adoption(db, user)
+    raw = _issue_token(db, user, "verify", timedelta(hours=1))
+    db.commit()
+
+    r = client.post("/auth/verify", json={"token": raw})
+
+    assert r.status_code == 200
+    assert r.json() == {
+        "ok": True,
+        "password_reset_required": True,
+        "email": "needspw@example.com",
+    }
+
+
+def test_verify_reports_no_reset_needed_for_an_intact_account(client, db, make_user):
+    from app.routes.auth import _issue_token
+
+    user = make_user(email="intact@example.com", email_verified=False, is_active=False)
+    raw = _issue_token(db, user, "verify", timedelta(hours=1))
+    db.commit()
+
+    r = client.post("/auth/verify", json={"token": raw})
+
+    assert r.status_code == 200
+    assert r.json() == {
+        "ok": True,
+        "password_reset_required": False,
+        "email": "intact@example.com",
+    }

backend/tests/test_channel_backfill.py

@@ -55,6 +55,49 @@ def test_channel_detail_returns_normal_shorts_live_counts(db, monkeypatch):
     assert body["count_normal"] == 2
 
 
+@pytest.mark.parametrize("hidden", [True, False])
+def test_channel_detail_surfaces_subscription_hidden_flag(db, monkeypatch, hidden):
+    # S6: the detail GET must expose the per-subscription `hidden` flag so the channel page can offer
+    # the same Unhide toggle the manager has (the flag was previously omitted from the detail dict).
+    ch = Channel(id="UC_hid", title="Hidden?", published_at=_PUB)
+    db.add(ch)
+    me = User(email="hid@example.com")
+    db.add(me)
+    db.flush()
+    db.add(Subscription(user_id=me.id, channel_id=ch.id, hidden=hidden))
+    db.commit()
+
+    monkeypatch.setattr(state, "_configured_cache", True)
+    app.dependency_overrides[get_db] = lambda: db
+    app.dependency_overrides[current_user] = lambda: me
+    try:
+        resp = TestClient(app).get(f"/api/channels/{ch.id}")
+    finally:
+        app.dependency_overrides.clear()
+
+    assert resp.status_code == 200, resp.text
+    assert resp.json()["hidden"] is hidden
+
+
+def test_channel_detail_hidden_defaults_false_when_not_subscribed(db, monkeypatch):
+    # No subscription row → the flag can't be True; it must serialize as False, not raise.
+    ch = Channel(id="UC_hid_ns", title="Unsub", published_at=_PUB)
+    me = User(email="hidns@example.com")
+    db.add_all([ch, me])
+    db.commit()
+
+    monkeypatch.setattr(state, "_configured_cache", True)
+    app.dependency_overrides[get_db] = lambda: db
+    app.dependency_overrides[current_user] = lambda: me
+    try:
+        resp = TestClient(app).get(f"/api/channels/{ch.id}")
+    finally:
+        app.dependency_overrides.clear()
+
+    assert resp.status_code == 200, resp.text
+    assert resp.json()["hidden"] is False
+
+
 def _setup_channel_and_sub(db, *, email, is_demo=False):
     ch = Channel(
         id="UC_wire",

backend/tests/test_download_credentials.py

@@ -0,0 +1,257 @@
+"""S6 — per-user, per-host download cookies: host-scope, cache privacy, encryption, write-only API.
+
+The two load-bearing security properties are covered as behaviour, not prose:
+  * **cache privacy** — a cookie-authed download is a PRIVATE, salted asset; a second user without a
+    cookie enqueuing the same URL gets the shared (unsalted) asset and can never be cache-served the
+    authed one, and the worker attaches a cookie ONLY to that private identity.
+  * **host scope (SEC-12)** — a cookie is resolved ONLY for a URL whose netloc the credential owns; a
+    look-alike or unrelated host resolves to no host_key and gets no cookie.
+
+Pure-logic parts run with no DB; the CRUD / enqueue-salting / API parts use the `db`/`as_user` lane.
+"""
+
+import os
+from pathlib import Path
+
+import pytest
+from cryptography.fernet import Fernet
+
+from app import security
+from app.downloads import credentials, formats, service
+from app.models import DownloadCredential, MediaAsset, User
+
+
+@pytest.fixture(autouse=True)
+def _fernet(monkeypatch):
+    # A throwaway key so encrypt/decrypt work without TOKEN_ENCRYPTION_KEY in the env (mirrors
+    # test_security). Autouse: every credential write in this module encrypts.
+    monkeypatch.setattr(security, "_fernet", Fernet(Fernet.generate_key()))
+
+
+COOKIES = "# Netscape HTTP Cookie File\n.facebook.com\tTRUE\t/\tTRUE\t0\tc_user\t123\n"
+
+
+# --- host scope (pure logic) ------------------------------------------------------------------
+
+
+class TestHostKeyForUrl:
+    def test_matches_a_supported_host(self):
+        assert credentials.host_key_for_url("https://www.facebook.com/watch?v=1") == "facebook"
+        assert credentials.host_key_for_url("https://fb.watch/abc/") == "facebook"
+        assert credentials.host_key_for_url("https://x.com/i/status/1") == "twitter"
+
+    def test_look_alike_host_never_matches(self):
+        assert credentials.host_key_for_url("https://myfacebook.com/x") is None
+        assert credentials.host_key_for_url("https://facebook.com.evil.test/x") is None
+
+    def test_unrelated_or_empty_url_has_no_host_key(self):
+        assert credentials.host_key_for_url("https://www.youtube.com/watch?v=abc") is None
+        assert credentials.host_key_for_url("") is None
+        assert credentials.host_key_for_url(None) is None
+
+
+class TestValidateCookies:
+    def test_accepts_a_netscape_file(self):
+        assert credentials.validate_cookies(COOKIES).endswith("\n")
+
+    def test_rejects_empty(self):
+        with pytest.raises(credentials.InvalidCookies):
+            credentials.validate_cookies("   ")
+
+    def test_rejects_non_cookie_paste(self):
+        # Comments only, no tab-separated data line -> not a usable cookies.txt.
+        with pytest.raises(credentials.InvalidCookies):
+            credentials.validate_cookies("just some pasted text\n# a comment")
+
+
+def test_authed_sig_differs_per_user_and_from_the_shared_sig():
+    spec = formats.normalize({})
+    shared = formats.format_sig(spec)
+    a = credentials.authed_format_sig(spec, 1, "facebook")
+    b = credentials.authed_format_sig(spec, 2, "facebook")
+    assert a != shared and b != shared and a != b
+
+
+def test_write_cookiefile_is_private_and_survives_the_retry_wipe(tmp_path):
+    staging = tmp_path / "staging"
+    staging.mkdir()
+    path = credentials._write_cookiefile(COOKIES, staging)
+    assert path.read_text() == COOKIES
+    # 0600 (owner-only) — POSIX perms only (the worker is Linux-only; Windows has no mode bits).
+    if os.name == "posix":
+        assert (path.stat().st_mode & 0o777) == 0o600
+    # It lives in a SUBDIR so the download retry loop (which unlinks files in the staging ROOT) and
+    # _produced_file (which scans the root) never see it.
+    assert path.parent == staging / ".auth"
+    assert not any(p.is_file() for p in staging.iterdir())
+
+
+# --- CRUD + encryption at rest (DB) -----------------------------------------------------------
+
+
+def _user(db, email="cred@example.com") -> User:
+    u = User(email=email)
+    db.add(u)
+    db.flush()
+    return u
+
+
+class TestCrud:
+    def test_upsert_stores_ciphertext_not_plaintext(self, db):
+        u = _user(db)
+        credentials.upsert_credential(db, u.id, "facebook", COOKIES)
+        db.commit()
+        row = db.get(DownloadCredential, 1)
+        assert row.cookies_enc != COOKIES  # encrypted at rest
+        assert COOKIES not in row.cookies_enc
+        assert security.decrypt(row.cookies_enc) == COOKIES
+
+    def test_upsert_replaces_in_place(self, db):
+        u = _user(db)
+        credentials.upsert_credential(db, u.id, "facebook", COOKIES)
+        db.commit()
+        credentials.upsert_credential(db, u.id, "facebook", COOKIES.replace("123", "999"))
+        db.commit()
+        rows = db.query(DownloadCredential).filter_by(user_id=u.id, host_key="facebook").all()
+        assert len(rows) == 1
+        assert "999" in security.decrypt(rows[0].cookies_enc)
+
+    def test_status_list_never_leaks_the_blob(self, db):
+        u = _user(db)
+        credentials.upsert_credential(db, u.id, "facebook", COOKIES)
+        db.commit()
+        status = credentials.status_list(db, u.id)
+        fb = next(h for h in status if h["host_key"] == "facebook")
+        assert fb["configured"] is True and fb["updated_at"] is not None
+        ig = next(h for h in status if h["host_key"] == "instagram")
+        assert ig["configured"] is False and ig["updated_at"] is None
+        # No field anywhere carries the cookie value.
+        assert all(COOKIES not in str(v) for h in status for v in h.values())
+
+    def test_delete(self, db):
+        u = _user(db)
+        credentials.upsert_credential(db, u.id, "facebook", COOKIES)
+        db.commit()
+        assert credentials.delete_credential(db, u.id, "facebook") is True
+        db.commit()
+        assert credentials.get_credential(db, u.id, "facebook") is None
+        assert credentials.delete_credential(db, u.id, "facebook") is False
+
+
+# --- the crux: enqueue salts privately, no cross-user cache serve (DB) -------------------------
+
+FB_URL = "https://www.facebook.com/watch?v=100"
+
+
+class TestCachePrivacy:
+    def test_enqueue_with_a_cookie_creates_a_private_salted_asset(self, db):
+        u = _user(db)
+        credentials.upsert_credential(db, u.id, "facebook", COOKIES)
+        db.commit()
+        job = service.enqueue(db, u.id, "url", FB_URL, {})
+        asset = db.get(MediaAsset, job.asset_id)
+        spec = formats.normalize({})
+        assert asset.format_sig == credentials.authed_format_sig(spec, u.id, "facebook")
+        assert asset.format_sig != formats.format_sig(spec)
+
+    def test_enqueue_without_a_cookie_uses_the_shared_sig(self, db):
+        u = _user(db)
+        job = service.enqueue(db, u.id, "url", FB_URL, {})
+        asset = db.get(MediaAsset, job.asset_id)
+        assert asset.format_sig == formats.format_sig(formats.normalize({}))
+
+    def test_two_users_never_share_the_authed_asset(self, db):
+        a = _user(db, "a@example.com")
+        b = _user(db, "b@example.com")
+        credentials.upsert_credential(db, a.id, "facebook", COOKIES)
+        db.commit()
+        ja = service.enqueue(db, a.id, "url", FB_URL, {})  # A: authed, private
+        jb = service.enqueue(db, b.id, "url", FB_URL, {})  # B: no cookie, shared
+        assert ja.asset_id != jb.asset_id
+        # B's asset is the shared identity — A's private group video can never be served to B.
+        assert db.get(MediaAsset, jb.asset_id).format_sig == formats.format_sig(
+            formats.normalize({})
+        )
+
+
+# --- the worker gate: attach only to the private identity, host-scoped (DB) --------------------
+
+
+class TestResolveCookiefile:
+    def _asset_sig(self, sig: str) -> MediaAsset:
+        return MediaAsset(
+            source_kind="url", source_ref=FB_URL, format_sig=sig, status="downloading"
+        )
+
+    def test_attaches_to_the_private_salted_asset(self, db, tmp_path):
+        u = _user(db)
+        credentials.upsert_credential(db, u.id, "facebook", COOKIES)
+        db.commit()
+        spec = formats.normalize({})
+        salted = credentials.authed_format_sig(spec, u.id, "facebook")
+        path = credentials.resolve_cookiefile(db, u.id, FB_URL, salted, spec, tmp_path)
+        assert path is not None and Path(path).read_text() == COOKIES
+
+    def test_never_attaches_to_a_shared_asset(self, db, tmp_path):
+        # Cookie exists, but the asset is the UNSALTED shared identity -> attaching would poison the
+        # global cache with a private-group video. Must return None.
+        u = _user(db)
+        credentials.upsert_credential(db, u.id, "facebook", COOKIES)
+        db.commit()
+        spec = formats.normalize({})
+        shared = formats.format_sig(spec)
+        assert credentials.resolve_cookiefile(db, u.id, FB_URL, shared, spec, tmp_path) is None
+
+    def test_non_matching_host_gets_no_cookie(self, db, tmp_path):
+        u = _user(db)
+        credentials.upsert_credential(db, u.id, "facebook", COOKIES)
+        db.commit()
+        spec = formats.normalize({})
+        # A YouTube URL has no supported host_key -> no cookie regardless of what's stored.
+        yt = "https://www.youtube.com/watch?v=abc"
+        salted = credentials.authed_format_sig(spec, u.id, "facebook")
+        assert credentials.resolve_cookiefile(db, u.id, yt, salted, spec, tmp_path) is None
+
+    def test_no_credential_gets_no_cookie(self, db, tmp_path):
+        u = _user(db)
+        spec = formats.normalize({})
+        salted = credentials.authed_format_sig(spec, u.id, "facebook")
+        assert credentials.resolve_cookiefile(db, u.id, FB_URL, salted, spec, tmp_path) is None
+
+
+# --- API: write-only, never echoes the blob (DB) ----------------------------------------------
+
+
+class TestApi:
+    def test_put_get_delete_roundtrip_never_returns_the_blob(self, db, as_user):
+        u = _user(db)
+        db.commit()
+        client = as_user(u)
+
+        r = client.put("/api/downloads/credentials/facebook", json={"cookies": COOKIES})
+        assert r.status_code == 200
+        body = r.json()
+        assert body["ok"] is True
+        assert COOKIES not in r.text  # the response must never carry the value
+        fb = next(h for h in body["hosts"] if h["host_key"] == "facebook")
+        assert fb["configured"] is True
+
+        r = client.get("/api/downloads/credentials")
+        assert r.status_code == 200 and COOKIES not in r.text
+
+        r = client.delete("/api/downloads/credentials/facebook")
+        assert r.status_code == 200
+        assert credentials.get_credential(db, u.id, "facebook") is None
+
+    def test_unknown_host_is_404(self, db, as_user):
+        u = _user(db)
+        db.commit()
+        r = as_user(u).put("/api/downloads/credentials/nope", json={"cookies": COOKIES})
+        assert r.status_code == 404
+
+    def test_bad_cookies_are_rejected(self, db, as_user):
+        u = _user(db)
+        db.commit()
+        r = as_user(u).put("/api/downloads/credentials/facebook", json={"cookies": "   "})
+        assert r.status_code == 400
+        assert r.json()["detail"]["code"] == "cookies"

backend/tests/test_download_deprioritize.py

@@ -0,0 +1,103 @@
+"""Worker-child resource de-prioritization (S4): the encoder thread cap, the `-threads` flag on the
+browser-safe re-encode, and the child's startup renice/ionice/OMP handicap. These keep a CPU-heavy
+transcode from pegging every core on the box it shares with the API, Postgres, and Plex playback."""
+
+import subprocess
+
+import pytest
+
+from app.config import settings
+from app.downloads import edit as editmod
+from app.downloads import runner
+
+
+class TestEncodeThreadCap:
+    def test_pinned_setting_wins(self, monkeypatch):
+        monkeypatch.setattr(settings, "download_ffmpeg_threads", 3)
+        assert editmod.encode_thread_cap() == 3
+
+    def test_zero_reserves_one_core(self, monkeypatch):
+        monkeypatch.setattr(settings, "download_ffmpeg_threads", 0)
+        monkeypatch.setattr(editmod.os, "cpu_count", lambda: 8)
+        assert editmod.encode_thread_cap() == 7
+
+    def test_single_core_box_never_caps_below_one(self, monkeypatch):
+        monkeypatch.setattr(settings, "download_ffmpeg_threads", 0)
+        monkeypatch.setattr(editmod.os, "cpu_count", lambda: 1)
+        assert editmod.encode_thread_cap() == 1
+
+    def test_unknown_cpu_count_falls_back(self, monkeypatch):
+        monkeypatch.setattr(settings, "download_ffmpeg_threads", 0)
+        monkeypatch.setattr(editmod.os, "cpu_count", lambda: None)
+        assert editmod.encode_thread_cap() == 1  # max(1, 2 - 1)
+
+
+class TestBrowserSafeThreads:
+    def test_threads_flag_added_when_capped(self):
+        cmd = editmod.build_browser_safe_cmd(
+            "/in.mkv", "/out.mp4", reencode_video=True, reencode_audio=False, threads=2
+        )
+        assert "-threads" in cmd
+        assert cmd[cmd.index("-threads") + 1] == "2"
+        # The cap precedes the output file, so it binds the encoder (not input decoding).
+        assert cmd.index("-threads") < cmd.index("/out.mp4")
+
+    @pytest.mark.parametrize("threads", [0, None])
+    def test_no_threads_flag_when_uncapped(self, threads):
+        cmd = editmod.build_browser_safe_cmd(
+            "/in.mkv", "/out.mp4", reencode_video=True, reencode_audio=False, threads=threads
+        )
+        assert "-threads" not in cmd
+
+
+class TestDeprioritize:
+    def test_renices_by_configured_increment(self, monkeypatch):
+        monkeypatch.setattr(settings, "download_child_nice", 12)
+        monkeypatch.setattr(settings, "download_child_ionice_class", 0)  # skip ionice branch
+        calls = []
+        monkeypatch.setattr(runner.os, "nice", lambda n: calls.append(n))
+        monkeypatch.setattr(runner.os, "environ", {})
+        runner._deprioritize()
+        assert calls == [12]
+
+    def test_nice_zero_does_not_renice(self, monkeypatch):
+        monkeypatch.setattr(settings, "download_child_nice", 0)
+        monkeypatch.setattr(settings, "download_child_ionice_class", 0)
+        calls = []
+        monkeypatch.setattr(runner.os, "nice", lambda n: calls.append(n))
+        monkeypatch.setattr(runner.os, "environ", {})
+        runner._deprioritize()
+        assert calls == []
+
+    def test_sets_omp_budget_to_thread_cap(self, monkeypatch):
+        monkeypatch.setattr(settings, "download_child_nice", 0)
+        monkeypatch.setattr(settings, "download_child_ionice_class", 0)
+        monkeypatch.setattr(settings, "download_ffmpeg_threads", 4)
+        env: dict = {}
+        monkeypatch.setattr(runner.os, "environ", env)
+        runner._deprioritize()
+        assert env["OMP_NUM_THREADS"] == "4"
+
+    def test_ionice_invoked_when_binary_present(self, monkeypatch):
+        monkeypatch.setattr(settings, "download_child_nice", 0)
+        monkeypatch.setattr(settings, "download_child_ionice_class", 3)
+        monkeypatch.setattr(runner.os, "environ", {})
+        monkeypatch.setattr(runner.shutil, "which", lambda name: "/usr/bin/ionice")
+        ran = []
+        monkeypatch.setattr(
+            runner.subprocess,
+            "run",
+            lambda cmd, **kw: ran.append(cmd) or subprocess.CompletedProcess(cmd, 0),
+        )
+        runner._deprioritize()
+        assert ran and ran[0][:3] == ["ionice", "-c", "3"]
+
+    def test_ionice_skipped_when_binary_absent(self, monkeypatch):
+        monkeypatch.setattr(settings, "download_child_nice", 0)
+        monkeypatch.setattr(settings, "download_child_ionice_class", 3)
+        monkeypatch.setattr(runner.os, "environ", {})
+        monkeypatch.setattr(runner.shutil, "which", lambda name: None)
+        ran = []
+        monkeypatch.setattr(runner.subprocess, "run", lambda cmd, **kw: ran.append(cmd))
+        runner._deprioritize()
+        assert ran == []

backend/tests/test_download_errors.py

@@ -14,6 +14,13 @@ def test_real_ytdlp_messages_map_to_categories():
         "ERROR: [youtube] abc: Sign in to confirm you're not a bot": "login_required",
         "ERROR: [youtube] abc: Join this channel to get access to members-only content": "login_required",
         "ERROR: [Reddit] 1vi1x56: Account authentication is required.": "login_required",
+        # Closed-group / private-post auth walls: yt-dlp either says to sign in or suggests cookies.
+        "ERROR: [facebook] 123: You must be logged in to see this post": "login_required",
+        "ERROR: [facebook] 123: Login required. Use --cookies for the authentication.": "login_required",
+        "ERROR: [instagram] abc: This content is only available for registered users": "login_required",
+        "ERROR: [youtube] abc: Sign in to confirm... Use --cookies-from-browser or --cookies": "login_required",
+        # A site yt-dlp has no extractor for at all — distinct from an auth wall, still non-retryable.
+        "ERROR: Unsupported URL: https://example.com/whatever": "unsupported_host",
         "ERROR: [youtube] abc: The uploader has not made this video available in your country": "geo_blocked",
         "ERROR: [youtube] abc: Requested format is not available": "format_unavailable",
         "ERROR: [youtube] abc: Only images are available for download": "format_unavailable",

backend/tests/test_download_output.py

@@ -6,7 +6,7 @@ with "PosixPath('.') has an empty name" instead of downloading."""
 
 import pytest
 
-from app.downloads.edit import _concat_quote, parse_probe_streams
+from app.downloads.edit import _codecs_from_streams, _concat_quote, run_ffprobe_json
 from app.downloads.pipeline import _media_info, _produced_file
 from pathlib import Path, PurePosixPath
 
@@ -105,39 +105,76 @@ class TestMediaInfo:
         assert _media_info(info)["id"] == "vid"
 
 
-class TestParseProbeStreams:
+class TestCodecsFromStreams:
     # ffprobe emits codec_name BEFORE codec_type, so the old line parser shifted every name onto
     # the previous stream and an H.264+AAC mp4 came back as (aac, None) → a needless re-encode.
+    # _codecs_from_streams reads each stream dict by its own codec_type, immune to that ordering.
     def test_reads_each_stream_by_its_own_type(self):
-        payload = '{"streams":[{"codec_name":"h264","codec_type":"video"},{"codec_name":"aac","codec_type":"audio"}]}'
-        assert parse_probe_streams(payload) == ("h264", "aac")
+        streams = [
+            {"codec_name": "h264", "codec_type": "video"},
+            {"codec_name": "aac", "codec_type": "audio"},
+        ]
+        assert _codecs_from_streams(streams) == ("h264", "aac")
 
     def test_audio_first_ordering_is_handled(self):
-        payload = '{"streams":[{"codec_name":"AAC","codec_type":"audio"},{"codec_name":"H264","codec_type":"video"}]}'
-        assert parse_probe_streams(payload) == ("h264", "aac")
+        streams = [
+            {"codec_name": "AAC", "codec_type": "audio"},
+            {"codec_name": "H264", "codec_type": "video"},
+        ]
+        assert _codecs_from_streams(streams) == ("h264", "aac")
 
     def test_extra_streams_do_not_win_over_the_first_of_their_kind(self):
-        payload = (
-            '{"streams":[{"codec_name":"h264","codec_type":"video"},'
-            '{"codec_name":"vp9","codec_type":"video"},'
-            '{"codec_name":"mov_text","codec_type":"subtitle"},'
-            '{"codec_name":"opus","codec_type":"audio"}]}'
-        )
-        assert parse_probe_streams(payload) == ("h264", "opus")
+        streams = [
+            {"codec_name": "h264", "codec_type": "video"},
+            {"codec_name": "vp9", "codec_type": "video"},
+            {"codec_name": "mov_text", "codec_type": "subtitle"},
+            {"codec_name": "opus", "codec_type": "audio"},
+        ]
+        assert _codecs_from_streams(streams) == ("h264", "opus")
 
     def test_audio_only_and_video_only(self):
-        assert parse_probe_streams('{"streams":[{"codec_name":"opus","codec_type":"audio"}]}') == (
+        assert _codecs_from_streams([{"codec_name": "opus", "codec_type": "audio"}]) == (
             None,
             "opus",
         )
-        assert parse_probe_streams('{"streams":[{"codec_name":"av1","codec_type":"video"}]}') == (
-            "av1",
-            None,
-        )
+        assert _codecs_from_streams([{"codec_name": "av1", "codec_type": "video"}]) == ("av1", None)
 
-    def test_garbage_is_not_a_crash(self):
-        assert parse_probe_streams("") == (None, None)
-        assert parse_probe_streams("not json") == (None, None)
+    def test_empty_stream_list(self):
+        assert _codecs_from_streams([]) == (None, None)
+
+
+class TestRunFfprobeJson:
+    """The single ffprobe-JSON invocation point (shared by probe_codecs + probe.probe_media). A failed
+    probe or unparseable output must degrade to None, not raise — the malformed-input safety the old
+    parse_probe_streams string parser used to own now lives here."""
+
+    def test_unparseable_output_returns_none(self, monkeypatch):
+        import subprocess
+
+        class _R:
+            stdout = "not json"
+
+        monkeypatch.setattr(subprocess, "run", lambda *a, **k: _R())
+        assert run_ffprobe_json(Path("x")) is None
+
+    def test_ffprobe_failure_returns_none(self, monkeypatch):
+        import subprocess
+
+        def _boom(*a, **k):
+            raise subprocess.CalledProcessError(1, "ffprobe")
+
+        monkeypatch.setattr(subprocess, "run", _boom)
+        assert run_ffprobe_json(Path("x")) is None
+
+    def test_parses_streams_from_valid_json(self, monkeypatch):
+        import subprocess
+
+        class _R:
+            stdout = '{"streams":[{"codec_name":"h264","codec_type":"video"}]}'
+
+        monkeypatch.setattr(subprocess, "run", lambda *a, **k: _R())
+        data = run_ffprobe_json(Path("x"), entries="stream=codec_type,codec_name")
+        assert _codecs_from_streams(data["streams"]) == ("h264", None)
 
 
 class TestConcatQuote:

backend/tests/test_email_alerts.py

@@ -0,0 +1,149 @@
+"""An undelivered email leaves a trace in the admins' inbox.
+
+Sending is deliberately fail-soft — a missing SMTP setting or a rejecting relay logs and returns
+False so nothing user-facing breaks. The cost of that used to be total silence: an instance whose
+SMTP was never filled in swallowed verification links, password resets and access-request notices,
+and the operator's first clue was somebody saying nothing arrived.
+"""
+
+import smtplib
+
+import pytest
+from sqlalchemy import select
+
+from app import email as email_mod
+from app.models import Notification
+
+
+@pytest.fixture(autouse=True)
+def _no_smtp_config(monkeypatch):
+    """Every test here drives the real `_send`, so make sure it never reaches a socket."""
+    monkeypatch.setattr(
+        email_mod,
+        "_smtp",
+        lambda: {"host": "", "port": 587, "user": "", "password": "", "from": ""},
+    )
+
+
+def _notifications(db, user_id: int) -> list[Notification]:
+    return list(
+        db.execute(
+            select(Notification)
+            .where(Notification.user_id == user_id, Notification.type == "email_undelivered")
+            .order_by(Notification.id)
+        )
+        .scalars()
+        .all()
+    )
+
+
+def test_a_skipped_email_notifies_every_admin(db, make_user):
+    admin_a = make_user(email="admin-a@example.com", role="admin")
+    admin_b = make_user(email="admin-b@example.com", role="admin")
+    plain = make_user(email="plain@example.com")
+
+    assert email_mod.send_test("someone@example.com", "en") is False  # fail-soft, as before
+
+    db.expire_all()
+    for admin in (admin_a, admin_b):
+        (n,) = _notifications(db, admin.id)
+        assert n.data["reason"] == "not_configured"
+        assert n.data["subject"] == "Siftlode SMTP test"
+        assert n.data["recipients"] == ["someone@example.com"]
+    assert _notifications(db, plain.id) == []  # not an operator's problem to see
+
+
+def test_the_notice_is_throttled_so_a_dead_relay_cannot_flood_the_inbox(db, make_user):
+    admin = make_user(email="admin@example.com", role="admin")
+
+    for _ in range(5):
+        email_mod.send_test("someone@example.com", "en")
+
+    db.expire_all()
+    assert len(_notifications(db, admin.id)) == 1
+
+
+def test_a_send_failure_is_reported_separately_from_a_missing_config(db, make_user, monkeypatch):
+    # A configured-but-rejecting relay is a different operator problem from an empty config, and the
+    # inbox copy differs — so the reason has to survive to the notification.
+    admin = make_user(email="admin@example.com", role="admin")
+    monkeypatch.setattr(
+        email_mod,
+        "_smtp",
+        lambda: {
+            "host": "smtp.example.com",
+            "port": 587,
+            "user": "u",
+            "password": "p",
+            "from": "Siftlode <u@example.com>",
+        },
+    )
+
+    def _boom(*a, **kw):
+        raise smtplib.SMTPException("nope")
+
+    monkeypatch.setattr(email_mod.smtplib, "SMTP", _boom)
+
+    assert email_mod.send_test("someone@example.com", "en") is False
+
+    db.expire_all()
+    (n,) = _notifications(db, admin.id)
+    assert n.data["reason"] == "send_failed"
+
+
+def test_no_admins_means_no_notification_and_no_error(db, make_user):
+    # A fresh instance can have no admin yet (the wizard has not run). The alert must stay silent
+    # rather than blowing up inside the fail-soft path it is supposed to make visible.
+    plain = make_user(email="plain@example.com")
+
+    assert email_mod.send_test("someone@example.com", "en") is False
+
+    db.expire_all()
+    assert _notifications(db, plain.id) == []
+
+
+def test_a_drop_with_nobody_to_tell_does_not_burn_the_hour(db, make_user):
+    # The throttle window must only be spent on a notice that was actually written. Otherwise a drop
+    # during setup — before any admin exists — silences the next hour for the admin created a minute
+    # later, which is exactly the blind spot this alert exists to remove.
+    email_mod.send_test("someone@example.com", "en")  # no admins yet
+    admin = make_user(email="admin@example.com", role="admin")
+
+    assert email_mod.send_test("someone@example.com", "en") is False
+
+    db.expire_all()
+    assert len(_notifications(db, admin.id)) == 1
+
+
+def test_a_failed_alert_does_not_burn_the_hour_either(db, make_user, monkeypatch):
+    admin = make_user(email="admin@example.com", role="admin")
+    boom = {"on": True}
+
+    def _maybe_boom(*a, **kw):
+        if boom["on"]:
+            raise RuntimeError("notification store is down")
+        from app.notifications import create_notification as real
+
+        return real(*a, **kw)
+
+    monkeypatch.setattr(email_mod, "create_notification", _maybe_boom)
+    email_mod.send_test("someone@example.com", "en")  # the write blows up; nothing recorded
+    boom["on"] = False
+
+    assert email_mod.send_test("someone@example.com", "en") is False
+
+    db.expire_all()
+    assert len(_notifications(db, admin.id)) == 1
+
+
+def test_a_broken_alert_never_breaks_the_send(db, make_user, monkeypatch):
+    # The alert is the fallback path; if IT fails, the caller must still get the ordinary fail-soft
+    # False rather than an exception surfacing from a background task.
+    make_user(email="admin@example.com", role="admin")
+
+    def _boom(*a, **kw):
+        raise RuntimeError("notification store is down")
+
+    monkeypatch.setattr(email_mod, "create_notification", _boom)
+
+    assert email_mod.send_test("someone@example.com", "en") is False

backend/tests/test_email_canonical.py

@@ -0,0 +1,347 @@
+"""One mailbox, many spellings — the canonical-email identity rule (E9.5 S3).
+
+Gmail delivers `x.y@gmail.com`, `xy@gmail.com` and `xy+tag@gmail.com` to ONE inbox. The invite gate
+used to compare literal strings, so on 2026-09-03 an approved user's Google sign-in became a silent
+SECOND access request: they had registered as `npeter83.temu@gmail.com`, and OAuth returned the
+account's stored primary `npeter83temu@gmail.com`. The `+tag` case fails every time — a Google account
+cannot contain `+`, so OAuth can only ever answer with the base address.
+
+The rule is narrow on purpose: dots are significant on most providers, and the Gmail dot rule does not
+hold for Google Workspace custom domains unless their admin enabled it.
+"""
+
+import pytest
+from sqlalchemy import select, text
+
+_UAT_PW = "correct horse battery"
+
+from app.auth import is_allowed
+from app.models import Invite, User
+from app.utils import canonical_email
+
+# (input, expected canonical) — the matrix the sprint promised, plus the shapes that must NOT fold.
+CASES = [
+    # Gmail: dots and +tags are noise…
+    ("npeter83.temu@gmail.com", "npeter83temu@gmail.com"),
+    ("npeter83temu@gmail.com", "npeter83temu@gmail.com"),
+    ("n.p.e.t.e.r@gmail.com", "npeter@gmail.com"),
+    ("user+siftlode@gmail.com", "user@gmail.com"),
+    ("u.ser+a+b@gmail.com", "user@gmail.com"),
+    ("USer.Name@GMail.COM", "username@gmail.com"),
+    # …and googlemail is the same mailbox as gmail.
+    ("user.name@googlemail.com", "username@gmail.com"),
+    # Everyone else: lowercase ONLY. Dots stay significant.
+    ("first.last@example.com", "first.last@example.com"),
+    ("First.Last@Example.COM", "first.last@example.com"),
+    ("first+tag@example.com", "first+tag@example.com"),
+    # A Workspace domain is not Gmail, however Gmail-ish it looks.
+    ("first.last@gmail.company.com", "first.last@gmail.company.com"),
+    # Degenerate input must not explode or invent an address.
+    ("", ""),
+    (None, ""),
+    ("not-an-email", "not-an-email"),
+    (".@gmail.com", ".@gmail.com"),
+]
+
+
+@pytest.mark.parametrize("raw,expected", CASES)
+def test_canonical_email(raw, expected):
+    assert canonical_email(raw) == expected
+
+
+def test_the_migration_sql_agrees_with_the_helper(db):
+    """The 0079 backfill reimplements canonical_email in SQL (a migration must not import app code
+    that keeps changing). That duplication is only safe while the two agree, so pin them together —
+    a drift here means rows backfilled into a form the application will never look up."""
+    import importlib.util
+    from pathlib import Path
+
+    path = Path(__file__).resolve().parents[1] / "alembic" / "versions" / "0079_email_canonical.py"
+    spec = importlib.util.spec_from_file_location("m0079", path)
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+
+    sql = module._CANON_SQL.format(col=":addr")
+    for raw, expected in CASES:
+        if raw is None:
+            continue  # the column is NOT NULL; the backfill skips NULL emails explicitly
+        got = db.execute(text(f"SELECT {sql}"), {"addr": raw}).scalar_one()
+        assert got == expected, f"SQL and helper disagree on {raw!r}: {got!r} != {expected!r}"
+
+
+def test_the_column_is_kept_in_sync_by_writing_the_email(db):
+    """No write site has to remember: the model validator derives it. If this breaks, every lookup
+    below silently stops matching."""
+    user = User(email="Dotted.Name+tag@GoogleMail.com")
+    db.add(user)
+    db.commit()
+    assert user.email == "Dotted.Name+tag@GoogleMail.com"  # stored AS TYPED — mail goes here
+    assert user.email_canonical == "dottedname@gmail.com"  # …matched on this
+
+    user.email = "someone.else@example.com"
+    db.commit()
+    assert user.email_canonical == "someone.else@example.com"
+
+
+def test_an_approval_covers_every_spelling_of_the_same_gmail_mailbox(db):
+    # THE 2026-09-03 lockout, in one assertion: approved under the dotted spelling, signing in with
+    # the primary Google returns.
+    db.add(Invite(email="npeter83.temu@gmail.com", status="approved"))
+    db.commit()
+
+    assert is_allowed(db, "npeter83temu@gmail.com") is True
+    assert is_allowed(db, "npeter83.temu@gmail.com") is True
+    assert is_allowed(db, "npeter83.temu+throwaway@gmail.com") is True
+
+
+def test_a_plus_tagged_registration_is_not_locked_out_after_approval(db):
+    # The case that ALWAYS broke: a Google account cannot contain `+`, so OAuth can only return the
+    # base address, and a literal match could never find the invite.
+    db.add(Invite(email="someone+siftlode@gmail.com", status="approved"))
+    db.commit()
+
+    assert is_allowed(db, "someone@gmail.com") is True
+
+
+def test_dots_stay_significant_outside_gmail(db):
+    db.add(Invite(email="first.last@example.com", status="approved"))
+    db.commit()
+
+    assert is_allowed(db, "first.last@example.com") is True
+    assert is_allowed(db, "firstlast@example.com") is False  # a DIFFERENT mailbox elsewhere
+
+
+def test_an_approved_row_wins_over_a_denied_sibling(db):
+    # Prod carries approved pairs for one mailbox (oldest 2026-06-16). The API cannot flip an approved
+    # invite to denied, so approved-beside-denied means the admin approved that mailbox under another
+    # spelling — not that they revoked it. Revoking is deleting the row or suspending the account.
+    db.add(Invite(email="two.spellings@gmail.com", status="denied"))
+    db.add(Invite(email="twospellings@gmail.com", status="approved"))
+    db.commit()
+
+    assert is_allowed(db, "twospellings@gmail.com") is True
+
+
+def test_a_denied_mailbox_stays_denied(db):
+    db.add(Invite(email="no.thanks@gmail.com", status="denied"))
+    db.commit()
+
+    assert is_allowed(db, "nothanks@gmail.com") is False
+
+
+def test_a_second_spelling_does_not_open_a_second_access_request(db):
+    """The other half of the 2026-09-03 report: the admin queue got a duplicate request for a user
+    who was already approved."""
+    from app.routes.auth import upsert_pending_invite
+
+    db.add(Invite(email="already.approved@gmail.com", status="approved"))
+    db.commit()
+
+    req = upsert_pending_invite(db, "alreadyapproved@gmail.com")
+
+    assert req.is_new is False  # nothing new to notify an admin about
+    assert req.invite is not None and req.invite.email == "already.approved@gmail.com"
+    assert len(db.execute(select(Invite)).scalars().all()) == 1
+
+
+def test_manually_whitelisting_another_spelling_reuses_the_row(db):
+    """How prod ended up with hartmann.peter1986@ AND hartmannpeter1986@ both approved on the same
+    day: the admin typed the other spelling and got a second row instead of a no-op."""
+    from app.routes.admin import add_invite, AddInviteIn
+
+    admin = User(email="admin@example.com", role="admin", is_active=True, email_verified=True)
+    db.add(admin)
+    db.add(Invite(email="hartmann.peter1986@gmail.com", status="approved"))
+    db.commit()
+
+    add_invite(AddInviteIn(email="hartmannpeter1986@gmail.com"), admin=admin, db=db)
+
+    rows = db.execute(select(Invite)).scalars().all()
+    assert len(rows) == 1
+    assert rows[0].email == "hartmann.peter1986@gmail.com"  # the original spelling is preserved
+
+
+def _capture_reset_links(monkeypatch) -> list[str]:
+    """Patch the reset mailer and collect the recipients it is asked to write to."""
+    from app.routes import auth as auth_mod
+
+    sent: list[str] = []
+    monkeypatch.setattr(
+        auth_mod.email_mod, "send_password_reset", lambda to, lang, link: sent.append(to)
+    )
+    return sent
+
+
+# --- signing in and recovering an account, whichever spelling of it the person types -------------
+#
+# The three flows that look an account up BY TYPED ADDRESS used to match literally, so a Gmail user
+# who registered `x.y@` and typed `xy@` met "Invalid email or password" at sign-in — and, worse,
+# total silence from password-reset and verify-resend, which answer uniformly by design.
+
+
+def test_the_password_works_with_any_spelling_of_the_same_mailbox(db):
+    from app.auth import find_user_by_email
+
+    make = User(
+        email="t.e.st+tag@gmail.com", email_verified=True, is_active=True, password_hash="x"
+    )
+    db.add(make)
+    db.commit()
+
+    for typed in (
+        "t.e.st+tag@gmail.com",  # as registered
+        "test@gmail.com",  # the mailbox itself
+        "t.e.st@gmail.com",  # dots only
+        "TEST@googlemail.com",  # the alias domain
+    ):
+        assert find_user_by_email(db, typed) is make, typed
+
+
+def test_an_unrelated_address_still_finds_nothing(db):
+    from app.auth import find_user_by_email
+
+    db.add(User(email="someone@gmail.com", email_verified=True, is_active=True))
+    db.commit()
+
+    assert find_user_by_email(db, "someoneelse@gmail.com") is None
+    assert find_user_by_email(db, "some.one@example.com") is None  # dots matter off Gmail
+
+
+def test_the_exact_spelling_wins_when_two_accounts_share_a_mailbox(db):
+    # Prod carries such a pair (ids 13 and 14). Whoever types their own address in full must land on
+    # their own account, not on whichever row happens to come first.
+    from app.auth import find_user_by_email
+
+    dotted = User(email="npeter83.temu@gmail.com", email_verified=True, is_active=True)
+    plain = User(email="npeter83temu@gmail.com", email_verified=True, is_active=True)
+    db.add_all([dotted, plain])
+    db.commit()
+
+    assert find_user_by_email(db, "npeter83.temu@gmail.com") is dotted
+    assert find_user_by_email(db, "npeter83temu@gmail.com") is plain
+
+
+def test_an_ambiguous_spelling_refuses_rather_than_guessing(db):
+    # Neither spelling is exact, and both are the same mailbox. Handing a password sign-in one of
+    # them at random would let someone into the wrong account, so this answers "no such account" —
+    # the same uniform reply the caller already gives.
+    from app.auth import find_user_by_email
+
+    db.add(User(email="npeter83.temu@gmail.com", email_verified=True, is_active=True))
+    db.add(User(email="npeter83temu@gmail.com", email_verified=True, is_active=True))
+    db.commit()
+
+    assert find_user_by_email(db, "n.peter83.temu+x@gmail.com") is None
+
+
+def test_a_reset_link_goes_to_the_address_on_the_account(db, monkeypatch):
+    """Typing another spelling must still reach the owner — and the mail must go to the address they
+    registered with, tag and all, not to the one typed into the form."""
+    from app.routes.auth import _send_reset_if_eligible
+
+    db.add(
+        User(
+            email="me+siftlode@gmail.com",
+            email_verified=True,
+            is_active=True,
+            password_hash="x",
+        )
+    )
+    db.commit()
+    sent = _capture_reset_links(monkeypatch)
+
+    _send_reset_if_eligible("me@gmail.com")
+
+    assert sent == ["me+siftlode@gmail.com"]
+
+
+# --- a Google sign-in must not rewrite the address its owner chose ------------------------------
+
+
+def test_a_google_sign_in_keeps_a_plus_tagged_address(db):
+    """People register as `me+siftlode@gmail.com` so a later leak from this site is identifiable.
+    Google returns the account's primary address, which can never contain `+`, so following it
+    blindly destroyed the tag on the first Google sign-in — and, since sign-in matches the stored
+    address first, stopped them signing in with the address they had chosen."""
+    from app.routes.auth import _sync_google_email
+
+    user = User(email="me+siftlode@gmail.com", email_verified=True, is_active=True)
+    db.add(user)
+    db.commit()
+
+    _sync_google_email(db, user, "me@gmail.com")
+
+    assert user.email == "me+siftlode@gmail.com"
+
+
+def test_a_google_sign_in_follows_a_real_mailbox_change(db):
+    # The case the sync exists for: the Google account genuinely moved to a different mailbox.
+    from app.routes.auth import _sync_google_email
+
+    user = User(email="old.address@gmail.com", email_verified=True, is_active=True)
+    db.add(user)
+    db.commit()
+
+    _sync_google_email(db, user, "brand-new@example.com")
+
+    assert user.email == "brand-new@example.com"
+
+
+def test_a_mailbox_change_is_refused_when_another_account_owns_it(db):
+    from app.routes.auth import _sync_google_email
+
+    db.add(User(email="taken@example.com", email_verified=True, is_active=True))
+    user = User(email="mover@gmail.com", email_verified=True, is_active=True)
+    db.add(user)
+    db.commit()
+
+    _sync_google_email(db, user, "taken@example.com")
+
+    assert user.email == "mover@gmail.com"  # unique constraint would have 500'd the sign-in
+
+
+# --- showing BOTH addresses, once there are two -------------------------------------------------
+
+
+def test_the_google_address_is_recorded_beside_the_registered_one(db):
+    """Since the sign-in no longer overwrites the registered address, the account has two true
+    addresses and only one was stored. This is the other half, for the UI to name."""
+    from app.routes.auth import _sync_google_email
+
+    user = User(email="me+siftlode@gmail.com", email_verified=True, is_active=True)
+    db.add(user)
+    db.commit()
+
+    user.google_email = "me@gmail.com"
+    _sync_google_email(db, user, "me@gmail.com")
+    db.commit()
+
+    assert user.email == "me+siftlode@gmail.com"  # still theirs
+    assert user.google_email == "me@gmail.com"  # …and now we know the other one
+
+
+def test_me_reports_the_google_address_only_when_it_differs(client, db, make_user):
+    """The comparison lives in one place so no surface has to repeat it — and so the account menu
+    stays exactly as it is for the majority, whose two addresses are the same string."""
+    same = make_user(email="plain@gmail.com", password=_UAT_PW)
+    same.google_email = "plain@gmail.com"
+    db.commit()
+    assert (
+        client.post(
+            "/auth/password-login", json={"email": "plain@gmail.com", "password": _UAT_PW}
+        ).status_code
+        == 200
+    )
+    assert client.get("/api/me").json()["google_email"] is None
+
+    client.post("/auth/logout")
+    tagged = make_user(email="me+siftlode@gmail.com", password=_UAT_PW)
+    tagged.google_email = "me@gmail.com"
+    db.commit()
+    assert (
+        client.post(
+            "/auth/password-login", json={"email": "me+siftlode@gmail.com", "password": _UAT_PW}
+        ).status_code
+        == 200
+    )
+    assert client.get("/api/me").json()["google_email"] == "me@gmail.com"

backend/tests/test_email_html_part.py

@@ -0,0 +1,121 @@
+"""Every outbound mail carries an HTML alternative, so its link is actually clickable.
+
+The bodies are plain text and stay that way — but a bare URL in a text/plain mail is only a link if
+the CLIENT chooses to linkify it. Gmail/Outlook/Apple Mail do; lighter web clients render the body
+verbatim and leave the verification or password-reset link as dead text, which is the entire point of
+those two messages. So `_send` now attaches an HTML part generated from the same plain body.
+
+These are pure-logic tests except the last one, which drives the real `_send` against a fake SMTP so
+the wire format itself is pinned, not just the helper.
+"""
+
+import pytest
+
+from app import email as email_mod
+
+_SMTP_OK = {
+    "host": "smtp.example.com",
+    "port": 587,
+    "user": "u",
+    "password": "p",
+    "from": "Siftlode <u@example.com>",
+}
+
+
+def test_a_bare_url_becomes_a_real_link():
+    # THE regression: this is what a client that does not linkify plain text was leaving as dead text.
+    out = email_mod._html_body(
+        "Confirm your email:\n\nhttps://siftlode.example/#verify=tok123\n\n— Siftlode"
+    )
+    assert '<a href="https://siftlode.example/#verify=tok123">' in out
+
+
+def test_interpolated_content_cannot_inject_markup():
+    # Bodies carry untrusted values — a requester's address in the admin notice, the operator contact.
+    # Escaping must run BEFORE linkification, or a crafted address becomes markup in every admin's mail.
+    out = email_mod._html_body('A request from <script>alert("x")</script> & co')
+    assert "<script>" not in out
+    assert "&lt;script&gt;" in out
+    assert "&amp; co" in out
+
+
+def test_a_query_string_keeps_its_escaped_ampersand_inside_the_href():
+    # `&` is escaped to `&amp;` before the linkifier sees it, which is also what an HTML attribute
+    # wants — so the href must carry the escaped form and nothing may be trimmed off it.
+    out = email_mod._html_body("https://siftlode.example/x?a=1&b=2")
+    assert (
+        '<a href="https://siftlode.example/x?a=1&amp;b=2">https://siftlode.example/x?a=1&amp;b=2</a>'
+        in out
+    )
+
+
+@pytest.mark.parametrize(
+    "body,href,trail",
+    [
+        ("See https://siftlode.example/x.", "https://siftlode.example/x", "."),
+        ("See https://siftlode.example/x, then sign in", "https://siftlode.example/x", ","),
+        ("See (https://siftlode.example/x)", "https://siftlode.example/x", ")"),
+    ],
+)
+def test_sentence_punctuation_stays_out_of_the_href(body, href, trail):
+    out = email_mod._html_body(body)
+    assert f'<a href="{href}">{href}</a>{trail}' in out
+
+
+def test_a_token_ending_in_a_url_safe_character_is_not_trimmed():
+    # token_urlsafe output can end in `-` or `_`; trimming either would hand the user a dead link.
+    for tok in ("abc-", "abc_"):
+        out = email_mod._html_body(f"https://siftlode.example/#reset={tok}")
+        assert f'href="https://siftlode.example/#reset={tok}"' in out
+
+
+def test_blank_lines_become_paragraphs_and_single_breaks_stay_inline():
+    out = email_mod._html_body("Hi,\n\nline one\nline two\n\n— Siftlode")
+    assert out.count("<p>") == 3
+    assert "<p>line one<br>line two</p>" in out
+
+
+def test_the_sent_message_is_multipart_with_the_plain_body_intact(monkeypatch):
+    # The wire format, not just the helper: text/plain stays the primary part and the source of
+    # truth, with text/html alongside it.
+    monkeypatch.setattr(email_mod, "_smtp", lambda: _SMTP_OK)
+    sent = []
+
+    class _FakeSMTP:
+        def __init__(self, *a, **kw):
+            pass
+
+        def __enter__(self):
+            return self
+
+        def __exit__(self, *a):
+            return False
+
+        def starttls(self, *a, **kw):
+            pass
+
+        def login(self, *a, **kw):
+            pass
+
+        def send_message(self, msg):
+            sent.append(msg)
+
+    monkeypatch.setattr(email_mod.smtplib, "SMTP", _FakeSMTP)
+
+    assert (
+        email_mod.send_verify_email(
+            "someone@example.com", "en", "https://siftlode.example/#verify=tok"
+        )
+        is True
+    )
+
+    (msg,) = sent
+    assert msg.get_content_type() == "multipart/alternative"
+    plain = msg.get_body(preferencelist=("plain",))
+    rich = msg.get_body(preferencelist=("html",))
+    assert plain is not None and rich is not None
+    # The plain part must be byte-for-byte the template's own body — the HTML part is derived from
+    # it, never a second copy that could drift.
+    assert "https://siftlode.example/#verify=tok" in plain.get_content()
+    assert "<a href=" not in plain.get_content()
+    assert '<a href="https://siftlode.example/#verify=tok">' in rich.get_content()

backend/tests/test_feed_views.py

@@ -162,11 +162,154 @@ _SUMMARY_CASES = [
     "show=all&tags={O1}&tags={O2}&tag_mode_other=and",
     "show=all&tags={U1}",  # user-owned tag (visibility == user.id branch)
     "show=all&tags={U1}&tags={L1}",  # user tag AND a system tag, cross-category
+    # "No tag" filter (item B): channels with no USER tag. It stays applied in the base pass, so the
+    # facet/count lockstep must still hold with it on (alone, and combined with a positive tag filter).
+    "show=all&untagged=true",
+    "show=all&untagged=true&tags={L1}",
     "show=all&q=clip",
     "show=unwatched",
 ]
 
 
+def test_untagged_filter_keeps_only_channels_the_user_has_not_tagged(db, as_user, make_user):
+    """The "No tag" filter (item B): `untagged=true` keeps only channels with NO tag the USER personally
+    attached (no user-owned ChannelTag). System/auto tags (user_id NULL) don't count, and another user's
+    tag on the same channel doesn't either."""
+    user = make_user(email="untagged@example.com")
+    other = make_user(email="someone-else@example.com")
+    mine = Tag(user_id=user.id, name="Fav", category="other")
+    sys_topic = Tag(user_id=None, name="Tech", category="topic")
+    theirs = Tag(user_id=other.id, name="TheirTag", category="other")
+    db.add_all([mine, sys_topic, theirs])
+    chans = {c: Channel(id=c, title=c, subscriber_count=10) for c in ("chMine", "chSys", "chNone")}
+    db.add_all(chans.values())
+    db.flush()
+    # chMine: the user's own tag → tagged. chSys: only a system tag + another user's tag → still
+    # "untagged" for THIS user. chNone: nothing at all → untagged.
+    db.add(ChannelTag(channel_id="chMine", tag_id=mine.id, user_id=user.id, source="user"))
+    db.add(ChannelTag(channel_id="chSys", tag_id=sys_topic.id, user_id=None, source="auto"))
+    db.add(ChannelTag(channel_id="chSys", tag_id=theirs.id, user_id=other.id, source="user"))
+    for cid in chans:
+        db.add(Subscription(user_id=user.id, channel_id=cid, priority=0, hidden=False))
+        db.add(_video(f"{cid}v", cid, f"{cid} clip"))
+    db.commit()
+    client = as_user(user)
+
+    # Off: every subscribed channel shows.
+    assert _feed_ids(client, "show=all") == {"chMinev", "chSysv", "chNonev"}
+    # On: only channels the user has NOT personally tagged (a system tag / another user's tag don't count).
+    assert _feed_ids(client, "show=all&untagged=true") == {"chSysv", "chNonev"}
+
+
+def test_feed_years_counts_ignore_the_date_narrowing_but_honour_other_filters(
+    db, as_user, make_user
+):
+    """The year facet (item 8 / E8·S2): `/api/feed/years` returns a per-year video count, newest first,
+    with the publish-date narrowing DROPPED (so switching years stays a drill-down) but every other
+    filter still applied (here: a channel pick)."""
+    user = make_user(email="years@example.com")
+    chans = {c: Channel(id=c, title=c, subscriber_count=10) for c in ("chX", "chY")}
+    db.add_all(chans.values())
+    db.flush()
+    # chX: 2 videos in 2024, 1 in 2022; chY: 1 in 2023 (should drop once we scope to chX).
+    spread = {
+        "chX": [(2024, 1), (2024, 2), (2022, 5)],
+        "chY": [(2023, 3)],
+    }
+    for cid, dates in spread.items():
+        db.add(Subscription(user_id=user.id, channel_id=cid, priority=0, hidden=False))
+        for i, (yr, day) in enumerate(dates):
+            db.add(
+                Video(
+                    id=f"{cid}v{i}",
+                    channel_id=cid,
+                    published_at=datetime(yr, 1, day, tzinfo=timezone.utc),
+                    title=f"{cid} clip {i}",
+                    is_short=False,
+                    live_status="none",
+                    via_search=False,
+                    via_explore=False,
+                )
+            )
+    db.commit()
+    client = as_user(user)
+
+    # All channels: every year present, counted, newest first.
+    resp = client.get("/api/feed/years?show=all")
+    assert resp.status_code == 200, resp.text
+    assert resp.json()["years"] == [
+        {"year": 2024, "count": 2},
+        {"year": 2023, "count": 1},
+        {"year": 2022, "count": 1},
+    ]
+
+    # A channel filter narrows the year list; a date narrowing is ignored (the point of the facet — so
+    # a selected year never zeroes out the others). Scoping to chX drops 2023, keeps 2024 (×2) + 2022.
+    resp = client.get("/api/feed/years?show=all&channel_ids=chX&published_after=2024-01-01")
+    assert resp.status_code == 200, resp.text
+    assert resp.json()["years"] == [
+        {"year": 2024, "count": 2},
+        {"year": 2022, "count": 1},
+    ]
+
+
+def test_feed_years_buckets_by_utc_year_under_a_non_utc_session(db, make_user):
+    """feed_years must bucket by UTC year to stay in lockstep with the year filter's UTC-pinned
+    published_after/before bounds. published_at is timestamptz; a bare extract('year', …) would use the
+    DB session timezone, so a video just before midnight UTC on New Year's Eve would bucket into the
+    wrong (local) year on a non-UTC session and disagree with the feed the year chip drills into. Called
+    directly on this session (the HTTP client uses a separate connection SET TIME ZONE wouldn't reach)."""
+    from sqlalchemy import text
+
+    from app.feedquery import feed_years
+
+    user = make_user(email="tz-years@example.com")
+    db.add(Channel(id="chTZ", title="chTZ", subscriber_count=1))
+    db.add(Subscription(user_id=user.id, channel_id="chTZ", priority=0, hidden=False))
+    # 2023-12-31 23:30 UTC — a positive-offset session tz local-shifts this into 2024.
+    db.add(
+        Video(
+            id="tzv0",
+            channel_id="chTZ",
+            published_at=datetime(2023, 12, 31, 23, 30, tzinfo=timezone.utc),
+            title="NYE clip",
+            is_short=False,
+            live_status="none",
+            via_search=False,
+            via_explore=False,
+        )
+    )
+    db.commit()
+
+    params: dict = {
+        "tags": [],
+        "tag_modes": {"language": "or", "topic": "or", "other": "or"},
+        "untagged": False,
+        "channel_ids": [],
+        "q": None,
+        "min_duration": None,
+        "max_duration": None,
+        "max_age_days": None,
+        "published_after": None,
+        "published_before": None,
+        "show_normal": True,
+        "include_shorts": False,
+        "include_live": False,
+        "show": "all",
+        "scope": "my",
+        "library_source": "organic",
+    }
+    db.execute(
+        text("SET TIME ZONE 'Asia/Tokyo'")
+    )  # +9: pushes the video's local wall-clock into 2024
+    try:
+        years = feed_years(db, user, **params)
+    finally:
+        db.execute(text("SET TIME ZONE 'UTC'"))  # SET (not SET LOCAL) survives rollback — reset it
+    # UTC bucketing keeps the boundary video in 2023; a bare session-tz extract would report 2024.
+    assert years == [{"year": 2023, "count": 1}]
+
+
 @pytest.mark.parametrize("case", _SUMMARY_CASES)
 def test_feed_summary_matches_count_plus_facets(db, as_user, make_user, case):
     # /feed/summary must return byte-identical numbers to the old /feed/count + /facets it replaces,

backend/tests/test_formats.py

@@ -1,6 +1,7 @@
-"""build_ydl_opts: the mp4 compat profile must SELECT H.264 (not merely prefer it), so shared
-downloads play on iOS/Safari, while custom vcodec / non-mp4 profiles opt out. See the iPad AV1
-broken-player fix."""
+"""build_ydl_opts: EVERY download is clamped to the mp4/H.264 compat profile (E7 browser-
+playability guarantee) and must SELECT H.264 (not merely prefer it), so shared downloads play in
+every browser incl. iOS/Safari. Non-mp4 containers and non-H.264 vcodecs are coerced, not honoured.
+See the iPad AV1 broken-player fix + E7 format narrowing."""
 
 from app.downloads import edit as editmod
 from app.downloads import formats
@@ -56,16 +57,37 @@ def test_max_height_caps_every_branch():
     assert fmt.count("[height<=?720]") >= 3  # applied to each avc1/fallback branch
 
 
-def test_explicit_vcodec_opts_out_of_avc1_selector():
+def test_explicit_vcodec_is_clamped_to_the_compat_selector():
+    # E7 browser-playability guarantee: a non-H.264 vcodec no longer opts out — normalize() coerces
+    # vcodec→None, so the avc1 selector (and mp4 merge) is used regardless of what was requested.
     opts = _opts({"mode": "av", "container": "mp4", "vcodec": "vp9"})
-    assert "vcodec^=avc1" not in opts["format"]
-    assert opts["format"] == "bestvideo+bestaudio/best"
-    assert "vcodec:vp9" in opts["format_sort"]
+    assert opts["format"].startswith("bestvideo[vcodec^=avc1]")
+    assert opts["merge_output_format"] == "mp4"
+    assert "vcodec:vp9" not in opts["format_sort"]
 
 
-def test_non_mp4_container_opts_out():
-    fmt = _opts({"mode": "av", "container": "webm"})["format"]
-    assert "vcodec^=avc1" not in fmt
+def test_non_mp4_container_is_clamped_to_mp4():
+    # A webm/mkv request is coerced to the mp4/H.264 compat profile (nothing plays mkv in-browser;
+    # webm/VP9 fails iOS), so the avc1 selector is used and the merge target is mp4.
+    opts = _opts({"mode": "av", "container": "webm"})
+    assert opts["format"].startswith("bestvideo[vcodec^=avc1]")
+    assert opts["merge_output_format"] == "mp4"
+
+
+def test_normalize_clamps_to_browser_playable():
+    n = formats.normalize({"container": "mkv", "vcodec": "av1", "audio_format": "opus"})
+    assert n["container"] == "mp4"
+    assert n["vcodec"] is None
+    assert n["audio_format"] == "m4a"
+    # A playable audio choice is preserved.
+    assert formats.normalize({"audio_format": "mp3"})["audio_format"] == "mp3"
+
+
+def test_non_playable_specs_dedup_to_the_compat_identity():
+    # Two requests that differ only in (now-clamped) non-playable fields share ONE cache asset.
+    a = formats.format_sig({"mode": "av", "max_height": 720, "container": "webm", "vcodec": "av1"})
+    b = formats.format_sig({"mode": "av", "max_height": 720, "container": "mp4"})
+    assert a == b
 
 
 def test_audio_only_unaffected():

backend/tests/test_gc.py

@@ -5,6 +5,8 @@ import os
 import time
 from pathlib import Path
 
+from app.config import settings
+from app.downloads import gc as gcmod
 from app.downloads.gc import _sweep_orphan_files
 
 
@@ -69,3 +71,38 @@ def test_sweep_removes_orphans_but_keeps_owned_system_and_fresh(tmp_path: Path):
     assert not (root / "OldChan").exists()
     assert sysfile.exists()  # system tree untouched
     assert fresh.exists()  # too new to sweep
+
+
+def test_sweep_throttles_after_each_batch(tmp_path: Path, monkeypatch):
+    """The whole-tree walk yields the IO channel after every `batch` files so it can't monopolize
+    disk IO in the API process. batch=2 over 5 touched files → 2 pauses (at file 2 and 4)."""
+    root = tmp_path
+    d = root / "Chan"
+    d.mkdir()
+    for i in range(5):
+        (d / f"orphan_{i}.dat").write_bytes(b"x")
+    for f in d.iterdir():
+        _aged(f, 5)  # old enough that every file is "touched" by the walk
+
+    monkeypatch.setattr(settings, "download_gc_sweep_pause_ms", 10)
+    monkeypatch.setattr(settings, "download_gc_sweep_batch", 2)
+    pauses = []
+    monkeypatch.setattr(gcmod.time, "sleep", lambda s: pauses.append(s))
+
+    _sweep_orphan_files(_StubDB([]), str(root))
+
+    assert pauses == [0.01, 0.01]  # 5 files, batch 2 → yield at #2 and #4
+
+
+def test_sweep_no_throttle_when_pause_disabled(tmp_path: Path, monkeypatch):
+    (tmp_path / "Chan").mkdir()
+    f = tmp_path / "Chan" / "orphan.dat"
+    f.write_bytes(b"x")
+    _aged(f, 5)
+    monkeypatch.setattr(settings, "download_gc_sweep_pause_ms", 0)
+    pauses = []
+    monkeypatch.setattr(gcmod.time, "sleep", lambda s: pauses.append(s))
+
+    _sweep_orphan_files(_StubDB([]), str(tmp_path))
+
+    assert pauses == []

backend/tests/test_links.py

@@ -4,7 +4,14 @@ token, rides in the file URL (a <video src> can't send a header), and expires.""
 from datetime import datetime, timedelta, timezone
 from types import SimpleNamespace
 
-from app.downloads.links import _GRANT_TTL, check_grant, is_expired, make_grant, new_token
+from app.downloads.links import (
+    _GRANT_TTL,
+    check_grant,
+    is_expired,
+    make_grant,
+    new_token,
+    public_meta,
+)
 
 
 def test_new_token_is_unguessable_and_unique():
@@ -48,6 +55,67 @@ class TestGrant:
             assert check_grant("tok", bad, 0) is False
 
 
+def _asset(**over):
+    base = dict(
+        title="Clip",
+        uploader="Someone",
+        uploader_url=None,
+        duration_s=42,
+        width=1280,
+        height=720,
+        vcodec="h264",
+        acodec="aac",
+        media_kind="video",
+        size_bytes=1000,
+        container="mp4",
+        source_webpage_url=None,
+        source_kind="url",
+    )
+    base.update(over)
+    return SimpleNamespace(**base)
+
+
+class TestPublicMetaAudioFlag:
+    """The watch page picks <audio> vs <video> from this flag; WebKit refuses an audio-only mp3 in a
+    <video>, so an audio-only asset (media_kind='audio') must report audio=True. The flag now reads
+    the stored media_kind (the single source), not a re-derived codec check."""
+
+    _link = SimpleNamespace(allow_download=True)
+
+    def test_audio_only_asset_is_flagged_audio(self):
+        asset = _asset(media_kind="audio", vcodec=None, acodec="mp3", width=None, height=None)
+        meta = public_meta(self._link, None, asset, "/f.mp3")
+        assert meta["audio"] is True
+
+    def test_a_video_asset_is_not_audio(self):
+        meta = public_meta(self._link, None, _asset(), "/f.mp4")
+        assert meta["audio"] is False
+
+    def test_a_generic_file_is_not_audio(self):
+        # A non-media upload (media_kind='file') has no player at all — never the audio bar.
+        meta = public_meta(self._link, None, _asset(media_kind="file"), "/f.bin")
+        assert meta["audio"] is False
+        assert meta["media_kind"] == "file"
+
+
+class TestCreateLinkDefault:
+    """D1 (E7 S3): a newly minted share link is downloadable by default. The one-click Share relies on
+    this — it POSTs no `allow_download`, so the API default decides. Forward-only lives here (the API
+    default), NOT in a migration: the DownloadLink column default stays False, so no existing back-
+    catalogue link silently flips to downloadable."""
+
+    def test_omitted_allow_download_defaults_downloadable(self):
+        from app.routes.downloads import CreateLinkIn
+
+        assert CreateLinkIn().allow_download is True
+
+    def test_explicit_false_is_respected(self):
+        # The owner can still uncheck it to mint a stream-only link.
+        from app.routes.downloads import CreateLinkIn
+
+        assert CreateLinkIn(allow_download=False).allow_download is False
+
+
 class TestIsExpired:
     def test_none_expiry_never_expires(self):
         assert is_expired(SimpleNamespace(expires_at=None)) is False

backend/tests/test_login_states.py

@@ -0,0 +1,107 @@
+"""What a refused sign-in SAYS (E9.5 S4), DB-lane.
+
+The states behind a 403 were true and useless: "Your account is awaiting admin approval." never
+revealed WHICH mailbox the account was on. On 2026-09-03 a registration as `npeter83.temu@gmail.com`
+met a Google claim of `npeter83temu@gmail.com`, and that missing address hid the mismatch for a day.
+So these pin the DETAIL, not just the status code — the address, and both gates, since E9.5 S1 made
+the two order-independent and the screen must report whichever is actually outstanding.
+
+The two refusals that answer BEFORE the password is proven carry nothing, and that is the security
+half of the same contract: `invalid` must stay byte-identical for a real account and an unknown one.
+"""
+
+from app.config import settings
+from app.models import Invite
+from app.routes.auth import _access_notice_url, upsert_pending_invite
+
+_PW = "correct horse battery"
+
+
+def _login(client, email, password=_PW):
+    return client.post("/auth/password-login", json={"email": email, "password": password})
+
+
+def test_pending_approval_names_the_address_the_account_is_on(client, make_user):
+    # The typed spelling and the stored one are the same mailbox; the screen must show the STORED
+    # one, because that is the mismatch a user cannot otherwise see.
+    make_user(email="np.temu@gmail.com", password=_PW, is_active=False)
+
+    detail = _login(client, "nptemu@gmail.com").json()["detail"]
+
+    assert detail["reason"] == "pending_approval"
+    assert detail["email"] == "np.temu@gmail.com"
+    assert detail["email_verified"] is True and detail["approved"] is False
+
+
+def test_an_already_approved_account_still_reports_its_missing_verification(client, make_user):
+    # S1 made the gates order-independent, so this really happens: approved, not yet verified. A
+    # screen that assumed a sequence would tell this user to wait for an admin who already decided.
+    make_user(
+        email="approved.first@example.com", password=_PW, email_verified=False, is_active=True
+    )
+
+    detail = _login(client, "approved.first@example.com").json()["detail"]
+
+    assert detail["reason"] == "email_unverified"
+    assert detail["email_verified"] is False and detail["approved"] is True
+
+
+def test_a_suspended_account_is_told_who_to_contact(client, make_user, monkeypatch):
+    monkeypatch.setattr(settings, "admin_emails", "ops@example.com")
+    make_user(email="banned@example.com", password=_PW, is_suspended=True)
+
+    r = _login(client, "banned@example.com")
+
+    assert r.status_code == 403
+    assert r.json()["detail"]["reason"] == "suspended"
+    assert r.json()["detail"]["operator"] == "ops@example.com"
+
+
+def test_a_refusal_before_the_password_is_proven_carries_no_account_detail(client, make_user):
+    make_user(email="real@example.com", password=_PW, is_active=False)
+
+    wrong_pw = _login(client, "real@example.com", "not the password").json()["detail"]
+    unknown = _login(client, "nobody@example.com").json()["detail"]
+
+    # No address, no flags — the pending state above must not leak through the wrong-password door.
+    assert wrong_pw == unknown == {"code": "login", "reason": "invalid"}
+
+
+# --- the access-request notice -------------------------------------------------------------------
+
+
+def test_the_access_notice_names_the_address_and_rides_the_fragment():
+    url = _access_notice_url("requested", "someone@example.com")
+
+    # A fragment never reaches a proxy access log or a Referer header — the same reasoning that put
+    # the verify/reset tokens there (SB3), applied to an address.
+    assert url == "/#access=requested&email=someone%40example.com"
+
+
+def test_a_plus_tagged_address_survives_the_round_trip():
+    # URLSearchParams reads a bare `+` in a fragment as a SPACE, so the encoder must emit %2B — or
+    # the very address family this epic exists to protect arrives mangled.
+    url = _access_notice_url("requested", "me+siftlode@gmail.com")
+
+    assert "me%2Bsiftlode%40gmail.com" in url and "+siftlode" not in url
+
+
+def test_a_request_already_on_file_under_another_spelling_says_so(db):
+    db.add(Invite(email="hartmann.peter@gmail.com", status="pending"))
+    db.commit()
+
+    req = upsert_pending_invite(db, "hartmannpeter@gmail.com")
+    url = _access_notice_url("requested", "hartmannpeter@gmail.com", req.invite)
+
+    assert req.is_new is False  # one mailbox, one request — no second row for the admin queue
+    assert "linked=hartmann.peter%40gmail.com" in url
+
+
+def test_the_same_spelling_twice_is_just_a_repeat_and_says_nothing_extra(db):
+    db.add(Invite(email="same@example.com", status="pending"))
+    db.commit()
+
+    req = upsert_pending_invite(db, "same@example.com")
+
+    # Nothing to explain: telling this user we "linked" their request to itself would be noise.
+    assert "linked" not in _access_notice_url("requested", "same@example.com", req.invite)

backend/tests/test_mail_language.py

@@ -0,0 +1,289 @@
+"""E9.5 S7 — every outbound mail is written in the reader's language.
+
+Two halves. The first is the catalog invariant: HU/EN parity with identical placeholders, enforced
+here because a mail is the one user-facing surface nobody can re-render by switching the UI language
+— it arrives once, in whatever language we picked. The second is the resolution chain: which
+language a given recipient actually gets, and where that signal was captured, since for an address
+with no account it exists only at the moment they asked us.
+"""
+
+import re
+import string
+
+import pytest
+from sqlalchemy import select
+
+from app import mailtext
+from app.models import Invite, User
+from app.routes import auth as auth_routes
+
+_PW = "correct horse battery"
+
+
+def _placeholders(template: str) -> set[str]:
+    return {name for _, name, _, _ in string.Formatter().parse(template) if name}
+
+
+# --- the catalog itself ---------------------------------------------------------------------------
+
+
+@pytest.mark.parametrize("key", sorted(mailtext.MAIL_TEXT))
+def test_every_mail_string_exists_in_both_languages(key):
+    assert set(mailtext.MAIL_TEXT[key]) == set(mailtext.SUPPORTED)
+
+
+@pytest.mark.parametrize("key", sorted(mailtext.MAIL_TEXT))
+def test_every_translation_takes_the_same_placeholders(key):
+    # The parity that actually bites: a translation that drops `{link}` renders a mail with no link
+    # in it, and a translation that invents one raises KeyError inside a background task nobody is
+    # watching. Both are silent in production and loud here.
+    variants = mailtext.MAIL_TEXT[key]
+    expected = _placeholders(variants[mailtext.DEFAULT])
+    for lang, template in variants.items():
+        assert _placeholders(template) == expected, f"{key} [{lang}]"
+
+
+def _app_sources_without_the_catalog() -> str:
+    """Every app source, with the catalog LITERAL cut out of mailtext.py.
+
+    Cutting it is the whole point: the dict spells each key as a quoted literal, so a scan that
+    included it reported every key as used no matter what the catalog held. Cutting the whole FILE
+    is too much, though — `link_expiry` legitimately asks for `duration.*`, and those keys would
+    then look orphaned."""
+    from pathlib import Path
+
+    app_dir = Path(__file__).resolve().parents[1] / "app"
+    out = []
+    for f in app_dir.rglob("*.py"):
+        src = f.read_text(encoding="utf-8")
+        if f.name == "mailtext.py":
+            src = src[: src.index("MAIL_TEXT: dict")]
+        out.append(src)
+    return "\n".join(out)
+
+
+def test_no_catalog_entry_is_orphaned():
+    """Every key is referenced from the app, so a mail that stopped being sent can't leave its text
+    behind to be 'kept up to date' by the next person who greps for it."""
+    sources = _app_sources_without_the_catalog()
+    assert [k for k in mailtext.MAIL_TEXT if f'"{k}"' not in sources] == []
+
+
+def test_every_key_the_app_asks_for_exists():
+    """The other direction, and the one that raises in production: `text()` looks the key up in a
+    dict, so a renamed or mistyped key is a KeyError inside a background task with no user in sight."""
+    asked = set(re.findall(r'text\(\s*"([a-z_]+\.[a-z_]+)"', _app_sources_without_the_catalog()))
+    assert asked, "the scan found no mailtext.text(...) call sites — the pattern has rotted"
+    assert sorted(asked - set(mailtext.MAIL_TEXT)) == []
+
+
+def test_an_unknown_language_falls_back_to_english_instead_of_raising():
+    # `preferences.language` is free-form JSON written by older builds and by locales we may stop
+    # shipping. A send that raised on one would take out a background task with no user in sight.
+    assert mailtext.text("test.subject", "de") == mailtext.text("test.subject", "en")
+    assert mailtext.text("test.subject", None) == mailtext.text("test.subject", "en")
+
+
+# --- who gets which language ----------------------------------------------------------------------
+
+
+def test_a_users_own_preference_decides_their_language(make_user):
+    hu = make_user(email="hu@example.com", preferences={"language": "hu"})
+    en = make_user(email="en@example.com", preferences={"language": "en"})
+    none = make_user(email="none@example.com", preferences=None)
+
+    assert mailtext.lang_for_user(hu) == "hu"
+    assert mailtext.lang_for_user(en) == "en"
+    assert mailtext.lang_for_user(none) == "en"
+
+
+def test_an_address_with_no_account_falls_back_to_the_language_it_asked_in(db):
+    db.add(Invite(email="asked@example.com", status="pending", lang="hu"))
+    db.commit()
+
+    assert mailtext.lang_for_email(db, "asked@example.com") == "hu"
+
+
+def test_the_account_wins_over_the_invite_row(db, make_user):
+    make_user(email="both@example.com", preferences={"language": "en"})
+    db.add(Invite(email="both@example.com", status="approved", lang="hu"))
+    db.commit()
+
+    # The invite records how they asked once; the account records what they have since chosen.
+    assert mailtext.lang_for_email(db, "both@example.com") == "en"
+
+
+def test_a_row_that_never_recorded_a_language_is_walked_past(db, make_user):
+    # Prod carries TWO accounts for one Gmail mailbox (the 2026-09-03 pair). Stopping at the first
+    # row would answer English for a person whose other account says Hungarian.
+    make_user(email="dup.one@gmail.com", preferences={})
+    make_user(email="dupone@gmail.com", preferences={"language": "hu"})
+
+    assert mailtext.lang_for_email(db, "dup.one@gmail.com") == "hu"
+
+
+def test_the_lookup_is_canonical_like_every_other_identity_match(db, make_user):
+    make_user(email="canon.match@gmail.com", preferences={"language": "hu"})
+
+    assert mailtext.lang_for_email(db, "canonmatch+tag@gmail.com") == "hu"
+
+
+# --- capturing the signal at the one moment it exists ---------------------------------------------
+
+
+def test_registration_records_the_language_of_the_sign_up_page(db, client):
+    r = client.post(
+        "/auth/register", json={"email": "signup@example.com", "password": _PW, "lang": "hu"}
+    )
+
+    assert r.status_code == 200
+    user = db.execute(select(User).where(User.email == "signup@example.com")).scalar_one()
+    assert (user.preferences or {}).get("language") == "hu"
+
+
+def test_an_access_request_records_the_language_it_was_made_in(db, client):
+    assert (
+        client.post(
+            "/auth/request-access", json={"email": "asking@example.com", "lang": "hu"}
+        ).status_code
+        == 200
+    )
+
+    inv = db.execute(select(Invite).where(Invite.email == "asking@example.com")).scalar_one()
+    assert inv.lang == "hu"
+
+
+def test_asking_again_from_another_language_updates_the_row(db, client):
+    client.post("/auth/request-access", json={"email": "asking@example.com", "lang": "en"})
+    client.post("/auth/request-access", json={"email": "asking@example.com", "lang": "hu"})
+
+    db.expire_all()
+    inv = db.execute(select(Invite).where(Invite.email == "asking@example.com")).scalar_one()
+    # The newest thing they told us wins — and there is still exactly one row (S3's canonical upsert).
+    assert inv.lang == "hu"
+    assert db.execute(select(Invite)).scalars().all() == [inv]
+
+
+def test_an_unsupported_language_is_ignored_rather_than_stored(db, client):
+    client.post("/auth/request-access", json={"email": "asking@example.com", "lang": "../../etc"})
+
+    inv = db.execute(select(Invite).where(Invite.email == "asking@example.com")).scalar_one()
+    assert inv.lang is None
+
+
+# --- the mails themselves -------------------------------------------------------------------------
+
+
+def _bodies(monkeypatch):
+    """Capture what `_send` would have put on the wire, rather than the arguments a caller passed —
+    the language only matters if it reaches the body."""
+    from app import email as email_mod
+
+    out: list[tuple[list[str], str, str]] = []
+    monkeypatch.setattr(
+        email_mod,
+        "_send",
+        lambda to, subject, body, reply_to=None: out.append((to, subject, body)) is None,
+    )
+    return out
+
+
+def test_the_confirmation_mail_is_written_in_the_accounts_language(db, client, monkeypatch):
+    from app import email as email_mod
+
+    monkeypatch.setattr(email_mod, "email_enabled", lambda db=None: True)
+    sent = _bodies(monkeypatch)
+
+    client.post("/auth/register", json={"email": "hu@example.com", "password": _PW, "lang": "hu"})
+
+    (_, subject, body) = sent[0]
+    assert subject == mailtext.MAIL_TEXT["verify_email.subject"]["hu"]
+    assert "#verify=" in body
+
+
+def test_the_approval_mail_answers_in_the_language_the_request_was_made_in(
+    db, client, make_user, as_user, monkeypatch
+):
+    from app import email as email_mod
+
+    monkeypatch.setattr(email_mod, "email_enabled", lambda db=None: True)
+    sent = _bodies(monkeypatch)
+    admin = make_user(email="admin@example.com", role="admin")
+    client.post("/auth/request-access", json={"email": "asking@example.com", "lang": "hu"})
+    inv = db.execute(select(Invite).where(Invite.email == "asking@example.com")).scalar_one()
+    sent.clear()  # drop the admin notification; this test is about the reply to the requester
+
+    r = as_user(admin).post(f"/api/admin/invites/{inv.id}/approve")
+
+    assert r.status_code == 200
+    (to, subject, _) = sent[0]
+    assert to == ["asking@example.com"]
+    assert subject == mailtext.MAIL_TEXT["access_approved.subject"]["hu"]
+
+
+def test_a_denial_answers_in_that_language_too(db, client, make_user, as_user, monkeypatch):
+    from app import email as email_mod
+
+    monkeypatch.setattr(email_mod, "email_enabled", lambda db=None: True)
+    sent = _bodies(monkeypatch)
+    admin = make_user(email="admin@example.com", role="admin")
+    client.post("/auth/request-access", json={"email": "asking@example.com", "lang": "hu"})
+    inv = db.execute(select(Invite).where(Invite.email == "asking@example.com")).scalar_one()
+    sent.clear()
+
+    as_user(admin).post(f"/api/admin/invites/{inv.id}/deny")
+
+    assert sent[0][1] == mailtext.MAIL_TEXT["access_denied.subject"]["hu"]
+
+
+def test_the_admins_pick_decides_an_invitation_and_is_remembered(
+    db, make_user, as_user, monkeypatch
+):
+    from app import email as email_mod
+
+    monkeypatch.setattr(email_mod, "email_enabled", lambda db=None: True)
+    sent = _bodies(monkeypatch)
+    admin = make_user(email="admin@example.com", role="admin")
+    # Hand-whitelisted: nobody has ever told us anything about this mailbox, which is exactly why
+    # the send button asks.
+    inv = Invite(email="stranger@example.com", status="approved")
+    db.add(inv)
+    db.commit()
+
+    r = as_user(admin).post(f"/api/admin/invites/{inv.id}/invite", json={"lang": "hu"})
+
+    assert r.status_code == 200
+    assert sent[0][1] == mailtext.MAIL_TEXT["access_invitation.subject"]["hu"]
+    db.expire_all()
+    # Recorded, so a later mail to this address matches the one the admin already sent.
+    assert db.get(Invite, inv.id).lang == "hu"
+
+
+def test_an_invitation_without_a_pick_still_goes_out(db, make_user, as_user, monkeypatch):
+    from app import email as email_mod
+
+    monkeypatch.setattr(email_mod, "email_enabled", lambda db=None: True)
+    sent = _bodies(monkeypatch)
+    admin = make_user(email="admin@example.com", role="admin")
+    inv = Invite(email="stranger@example.com", status="approved")
+    db.add(inv)
+    db.commit()
+
+    r = as_user(admin).post(f"/api/admin/invites/{inv.id}/invite")
+
+    assert r.status_code == 200
+    assert sent[0][1] == mailtext.MAIL_TEXT["access_invitation.subject"]["en"]
+    db.expire_all()
+    # Nothing was picked, so nothing is remembered: the column means "what this person told us",
+    # not "what we last defaulted to".
+    assert db.get(Invite, inv.id).lang is None
+
+
+def test_admins_are_notified_in_their_own_languages(db, make_user):
+    make_user(email="hu.admin@example.com", role="admin", preferences={"language": "hu"})
+    make_user(email="en.admin@example.com", role="admin", preferences={"language": "en"})
+
+    groups = auth_routes.admin_notify_groups(db)
+
+    # One mail per language, not one blast that has to be wrong for somebody.
+    assert groups == {"hu": ["hu.admin@example.com"], "en": ["en.admin@example.com"]}

backend/tests/test_me_email_flag.py

@@ -0,0 +1,58 @@
+"""/api/me carries whether this instance can actually send email.
+
+It drives the operator warnings on the Configuration and Access-requests screens. Admin-only,
+because it is an operator concern and a regular user has nothing to do with it.
+"""
+
+from app import email as email_mod
+
+_PW = "correct horse battery"
+
+
+def _signed_in(client, make_user, **kw):
+    """/api/me resolves its user through optional_current_user, which the as_user override does not
+    cover — so sign in for real and read the bootstrap payload the SPA actually gets."""
+    user = make_user(password=_PW, **kw)
+    assert (
+        client.post("/auth/password-login", json={"email": user.email, "password": _PW}).status_code
+        == 200
+    )
+    r = client.get("/api/me")
+    assert r.status_code == 200 and r.json()["authenticated"] is True
+    return r.json()
+
+
+def test_an_admin_is_told_when_email_is_not_configured(client, make_user, monkeypatch):
+    monkeypatch.setattr(email_mod, "email_enabled", lambda db=None: False)
+
+    me = _signed_in(client, make_user, email="admin@example.com", role="admin")
+
+    assert me["email_configured"] is False
+
+
+def test_an_admin_sees_nothing_wrong_when_email_works(client, make_user, monkeypatch):
+    monkeypatch.setattr(email_mod, "email_enabled", lambda db=None: True)
+
+    me = _signed_in(client, make_user, email="admin@example.com", role="admin")
+
+    assert me["email_configured"] is True
+
+
+def test_a_regular_user_is_never_warned_about_the_mail_setup(client, make_user, monkeypatch):
+    # Not their problem, and the flag must not become a way to probe the instance's configuration.
+    monkeypatch.setattr(email_mod, "email_enabled", lambda db=None: False)
+
+    me = _signed_in(client, make_user, email="plain@example.com")
+
+    assert me["email_configured"] is True
+
+
+def test_the_flag_reuses_the_request_session(client, make_user, monkeypatch):
+    # /api/me is polled once a minute per open tab; reading the SMTP settings decrypts a Fernet
+    # value, so it must not also check out a second pooled connection each time.
+    seen: list[object] = []
+    monkeypatch.setattr(email_mod, "email_enabled", lambda db=None: seen.append(db) or True)
+
+    _signed_in(client, make_user, email="admin@example.com", role="admin")
+
+    assert seen and seen[0] is not None

backend/tests/test_playlist_merge.py

@@ -0,0 +1,360 @@
+"""S7 — two-way (3-way) YouTube playlist merge.
+
+The load-bearing property: an item added (or deleted) on EITHER side survives the sync — the old
+push was one-directional (local wins, deletes everything not local from YouTube), so YouTube-side
+adds were lost. Pure-merge classification runs with no DB; the apply path uses the `db` lane with a
+fake YouTube client so both the local rows and the simulated YouTube state can be asserted.
+"""
+
+from datetime import datetime, timezone
+
+import pytest
+
+from app.models import Channel, Playlist, PlaylistItem, Video
+from app.sync import playlists as pl_mod
+from app.sync.playlists import (
+    merge_plan,
+    merge_playlist,
+    parse_baseline,
+    parse_unavailable,
+    plan_merge,
+)
+from app.youtube.client import YouTubeError
+
+# --- pure merge classification (no DB) --------------------------------------------------------
+
+
+class TestMergePlan:
+    def test_no_baseline_unions_losslessly(self):
+        # First-ever merge: can't tell an add from a delete, so keep everything, delete nothing.
+        mp = merge_plan(None, local=["a", "b"], youtube=["b", "c"])
+        assert mp.add_to_yt == ["a"]  # local-only pushed out
+        assert mp.add_to_local == ["c"]  # youtube-only pulled in
+        assert mp.remove_from_yt == [] and mp.remove_from_local == []
+        assert mp.final == ["a", "b", "c"]  # local order, youtube-only appended
+        assert mp.baseline_known is False
+
+    def test_adds_on_both_sides_both_survive(self):
+        # baseline b,c ; local added 'a' ; youtube added 'd' — nothing deleted.
+        mp = merge_plan(["b", "c"], local=["a", "b", "c"], youtube=["b", "c", "d"])
+        assert mp.add_to_yt == ["a"]
+        assert mp.add_to_local == ["d"]
+        assert mp.remove_from_yt == [] and mp.remove_from_local == []
+        assert mp.final == ["a", "b", "c", "d"]
+
+    def test_genuine_local_delete_propagates_to_youtube(self):
+        # baseline a,b,c ; local removed 'b' ; youtube unchanged -> remove b from youtube.
+        mp = merge_plan(["a", "b", "c"], local=["a", "c"], youtube=["a", "b", "c"])
+        assert mp.remove_from_yt == ["b"]
+        assert mp.add_to_yt == [] and mp.add_to_local == []
+        assert mp.final == ["a", "c"]
+
+    def test_genuine_youtube_delete_propagates_to_local(self):
+        # baseline a,b,c ; youtube removed 'b' ; local unchanged -> remove b from local.
+        mp = merge_plan(["a", "b", "c"], local=["a", "b", "c"], youtube=["a", "c"])
+        assert mp.remove_from_local == ["b"]
+        assert mp.final == ["a", "c"]
+
+    def test_delete_on_both_sides_is_gone_not_a_conflict(self):
+        mp = merge_plan(["a", "b", "c"], local=["a", "c"], youtube=["a", "c"])
+        assert mp.remove_from_yt == [] and mp.remove_from_local == []
+        assert mp.final == ["a", "c"]
+
+    def test_a_local_delete_beats_a_stale_youtube_copy(self):
+        # 'b' was synced, deleted locally, still present on youtube -> it must be removed there,
+        # NOT resurrected into local as a youtube-add.
+        mp = merge_plan(["a", "b"], local=["a"], youtube=["a", "b"])
+        assert mp.add_to_local == []
+        assert mp.remove_from_yt == ["b"]
+        assert "b" not in mp.final
+
+
+# --- apply path (db lane + fake YouTube) ------------------------------------------------------
+
+
+class FakeYouTube:
+    """Enough of YouTubeClient for merge_playlist: an in-memory playlist of (item_id, video_id)
+    and the write ops that mutate it. Every catalog video is pre-seeded so _ensure_videos never
+    needs get_videos."""
+
+    def __init__(
+        self,
+        *,
+        title: str,
+        items: list[str],
+        unavailable: set[str] | None = None,
+        fail_add: set[str] | None = None,
+    ):
+        self.title = title
+        self._seq = 0
+        self.items = [(self._new_id(), v) for v in items]
+        # Ids the Data API won't return (private/deleted) — get_videos omits them, so _ensure_videos
+        # can't ingest them. They still live in the playlist (`items`) like a real un-ingestable video.
+        self.unavailable = set(unavailable or ())
+        # Ids whose add_playlist_item raises, to exercise the partial-failure baseline-hold path.
+        self.fail_add = set(fail_add or ())
+
+    def _new_id(self) -> str:
+        self._seq += 1
+        return f"it{self._seq}"
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *exc):
+        return False
+
+    def create_playlist(self, title, description="", privacy="private"):
+        self.title = title
+        return "PLnew"
+
+    def get_playlist_snippet(self, pid):
+        return {"title": self.title}
+
+    def iter_playlist_items_with_ids(self, pid):
+        return [{"item_id": iid, "video_id": v} for iid, v in self.items]
+
+    def get_videos(self, ids):
+        # Mirror the Data API: a minimal ingestable record for each id, EXCEPT the un-ingestable
+        # ones (private/deleted), which are simply absent from the response.
+        return [
+            {
+                "id": v,
+                "snippet": {
+                    "channelId": "UCtest",
+                    "channelTitle": "Test",
+                    "publishedAt": "2020-01-01T00:00:00Z",
+                },
+            }
+            for v in ids
+            if v not in self.unavailable
+        ]
+
+    def update_playlist_title(self, pid, title):
+        self.title = title
+
+    def add_playlist_item(self, pid, vid, position=None):
+        if vid in self.fail_add:
+            raise YouTubeError("simulated add failure")
+        iid = self._new_id()
+        self.items.append((iid, vid))
+        return iid
+
+    def delete_playlist_item(self, item_id):
+        self.items = [(iid, v) for iid, v in self.items if iid != item_id]
+
+    def move_playlist_item(self, item_id, pid, vid, position):
+        row = next((r for r in self.items if r[0] == item_id), None)
+        if row is not None:
+            self.items.remove(row)
+            self.items.insert(position, row)
+
+    @property
+    def video_ids(self) -> list[str]:
+        return [v for _, v in self.items]
+
+
+def _seed_videos(db, ids):
+    db.add(Channel(id="UCtest", title="Test"))
+    now = datetime.now(timezone.utc)
+    for v in ids:
+        db.add(Video(id=v, channel_id="UCtest", published_at=now))
+    db.commit()
+
+
+def _linked_playlist(db, user, *, local_ids, baseline):
+    pl = Playlist(
+        user_id=user.id,
+        name="Mix",
+        source="local",
+        yt_playlist_id="PLyt",
+        synced_video_ids=None if baseline is None else pl_mod._dump_ids(baseline),
+    )
+    db.add(pl)
+    db.flush()
+    for pos, v in enumerate(local_ids):
+        db.add(PlaylistItem(playlist_id=pl.id, video_id=v, position=pos))
+    db.commit()
+    return pl
+
+
+def _local_ids(db, pl):
+    return pl_mod._local_video_ids(db, pl)
+
+
+@pytest.fixture
+def _fake_yt(monkeypatch):
+    holder = {}
+
+    def install(fake):
+        holder["fake"] = fake
+        monkeypatch.setattr(pl_mod, "YouTubeClient", lambda db, user: fake)
+        return fake
+
+    return install
+
+
+def test_adds_on_both_sides_survive_on_both_sides(db, make_user, _fake_yt):
+    user = make_user()
+    _seed_videos(db, ["a", "b", "c", "d"])
+    # baseline b,c ; local added 'a' ; youtube added 'd'
+    pl = _linked_playlist(db, user, local_ids=["a", "b", "c"], baseline=["b", "c"])
+    fake = _fake_yt(FakeYouTube(title="Mix", items=["b", "c", "d"]))
+
+    r = merge_playlist(db, user, pl)
+
+    assert r["failures"] == []
+    assert set(_local_ids(db, pl)) == {"a", "b", "c", "d"}, "youtube-add 'd' pulled into Siftlode"
+    assert set(fake.video_ids) == {"a", "b", "c", "d"}, "local-add 'a' pushed to YouTube"
+    assert r["inserted"] == 1 and r["pulled"] == 1
+    # Baseline advanced to the merged set so a re-sync is a no-op.
+    assert set(parse_baseline(pl)) == {"a", "b", "c", "d"}
+
+
+def test_a_genuine_delete_propagates_without_collateral_loss(db, make_user, _fake_yt):
+    user = make_user()
+    _seed_videos(db, ["a", "b", "c", "d"])
+    # baseline a,b,c ; local removed 'b' ; youtube added 'd' (a real add, must NOT be collateral)
+    pl = _linked_playlist(db, user, local_ids=["a", "c"], baseline=["a", "b", "c"])
+    fake = _fake_yt(FakeYouTube(title="Mix", items=["a", "b", "c", "d"]))
+
+    r = merge_playlist(db, user, pl)
+
+    assert r["failures"] == []
+    assert set(fake.video_ids) == {"a", "c", "d"}, "'b' removed on YouTube, 'd' kept"
+    assert set(_local_ids(db, pl)) == {"a", "c", "d"}, "'d' pulled in, 'b' stays deleted"
+    assert r["deleted"] == 1
+
+
+def test_first_merge_with_no_baseline_never_deletes(db, make_user, _fake_yt):
+    user = make_user()
+    _seed_videos(db, ["a", "b", "c"])
+    pl = _linked_playlist(db, user, local_ids=["a", "b"], baseline=None)
+    fake = _fake_yt(FakeYouTube(title="Mix", items=["b", "c"]))
+
+    r = merge_playlist(db, user, pl)
+
+    assert r["deleted"] == 0 and r["removed_local"] == 0
+    assert set(_local_ids(db, pl)) == {"a", "b", "c"}
+    assert set(fake.video_ids) == {"a", "b", "c"}
+    assert parse_baseline(pl) is not None, "a baseline is recorded after the first union"
+
+
+def test_create_path_appends_and_records_baseline(db, make_user, _fake_yt):
+    user = make_user()
+    _seed_videos(db, ["a", "b"])
+    pl = Playlist(user_id=user.id, name="Fresh", source="local")
+    db.add(pl)
+    db.flush()
+    for pos, v in enumerate(["a", "b"]):
+        db.add(PlaylistItem(playlist_id=pl.id, video_id=v, position=pos))
+    db.commit()
+    _fake_yt(FakeYouTube(title="Fresh", items=[]))
+
+    r = merge_playlist(db, user, pl)
+
+    assert r["created"] == 1 and r["inserted"] == 2
+    assert pl.yt_playlist_id  # created and linked
+    assert parse_baseline(pl) == ["a", "b"]
+
+
+def test_reorder_reaches_the_merged_order_on_youtube(db, make_user, _fake_yt):
+    # Same membership on both sides, but the user reordered locally to c,a,b. The apply-side
+    # insertion-sort must drive YouTube to that exact order — asserted as an ordered list, not a
+    # set, so an off-by-one or a dropped reorder pass can't pass unnoticed.
+    user = make_user()
+    _seed_videos(db, ["a", "b", "c"])
+    pl = _linked_playlist(db, user, local_ids=["c", "a", "b"], baseline=["a", "b", "c"])
+    fake = _fake_yt(FakeYouTube(title="Mix", items=["a", "b", "c"]))
+
+    r = merge_playlist(db, user, pl)
+
+    assert r["failures"] == []
+    assert fake.video_ids == ["c", "a", "b"], "YouTube order matches the merged (local) order"
+    assert r["reordered"] >= 1
+    assert parse_baseline(pl) == ["c", "a", "b"]
+
+
+def test_partial_youtube_failure_holds_the_baseline_for_retry(db, make_user, _fake_yt):
+    # A local-add whose YouTube insert fails must NOT advance the baseline — otherwise the retry
+    # sync would read the un-pushed add as a genuine YouTube-side delete and silently drop it.
+    user = make_user()
+    _seed_videos(db, ["a", "b", "c"])
+    pl = _linked_playlist(db, user, local_ids=["a", "b", "c"], baseline=["b", "c"])
+    fake = _fake_yt(FakeYouTube(title="Mix", items=["b", "c"], fail_add={"a"}))
+
+    r = merge_playlist(db, user, pl)
+
+    assert r["failures"] == ["a"], "the failed local-add is reported"
+    assert "a" not in fake.video_ids, "the add never landed on YouTube"
+    # Baseline is UNCHANGED so the next sync re-classifies 'a' as a local-add and re-pushes it,
+    # rather than treating it as a YouTube delete and removing it locally.
+    assert parse_baseline(pl) == ["b", "c"]
+    assert "a" in set(_local_ids(db, pl)), "'a' stays local for the retry"
+
+
+def test_unavailable_youtube_video_converges(db, make_user, _fake_yt):
+    # A YouTube-only video that can't be ingested (private/deleted) must not make the playlist
+    # loop forever re-classifying it as a pending pull. It is recorded as un-ingestable and skipped
+    # by the next merge; the playlist reports "up to date".
+    user = make_user()
+    _seed_videos(db, ["a", "b"])  # note: 'x' is NOT in the catalog and can't be ingested
+    pl = _linked_playlist(db, user, local_ids=["a", "b"], baseline=["a", "b"])
+    fake = _fake_yt(FakeYouTube(title="Mix", items=["a", "b", "x"], unavailable={"x"}))
+
+    r1 = merge_playlist(db, user, pl)
+
+    assert r1["failures"] == []
+    assert r1["pulled"] == 0, "the un-ingestable video did not become a local row"
+    assert set(_local_ids(db, pl)) == {"a", "b"}
+    assert parse_unavailable(pl) == {"x"}, "'x' recorded as un-ingestable"
+    assert "x" in fake.video_ids, "'x' left untouched on YouTube"
+
+    # Second sync: the preview reports nothing pending (plan_merge filters 'x' via the stored
+    # unavailable set). The sync itself re-attempts ingestion of 'x' (the heal path), but since it
+    # still won't ingest, 'x' stays recorded as unavailable — no perpetual pending pull.
+    plan = plan_merge(db, user, pl)
+    assert plan["add_local"] == 0, "no perpetual pending pull — the playlist is up to date"
+    r2 = merge_playlist(db, user, pl)
+    assert r2["pulled"] == 0 and r2["failures"] == []
+    assert parse_unavailable(pl) == {"x"}
+    assert "x" in fake.video_ids
+
+
+def test_unavailable_video_that_becomes_available_is_pulled_in(db, make_user, _fake_yt):
+    # A video marked un-ingestable (e.g. private) that later becomes available (public) must
+    # re-enter the merge on a normal sync — not stay skipped forever.
+    user = make_user()
+    _seed_videos(db, ["a", "b"])
+    pl = _linked_playlist(db, user, local_ids=["a", "b"], baseline=["a", "b"])
+    fake = _fake_yt(FakeYouTube(title="Mix", items=["a", "b", "x"], unavailable={"x"}))
+
+    merge_playlist(db, user, pl)
+    assert parse_unavailable(pl) == {"x"}, "recorded un-ingestable on the first sync"
+
+    # 'x' becomes available; the next sync re-attempts ingestion and pulls it in.
+    fake.unavailable.clear()
+    r2 = merge_playlist(db, user, pl)
+
+    assert r2["failures"] == []
+    assert "x" in set(_local_ids(db, pl)), "the now-available video is pulled into Siftlode"
+    assert parse_unavailable(pl) == set(), "'x' is no longer marked un-ingestable"
+
+
+def test_unavailable_id_that_leaves_youtube_is_pruned(db, make_user, _fake_yt):
+    # A recorded un-ingestable id that is later removed from the YouTube playlist must be pruned
+    # from the persisted `unavailable` set (the `& yt_id_set` self-heal), not carried forever.
+    user = make_user()
+    _seed_videos(db, ["a", "b"])
+    pl = _linked_playlist(db, user, local_ids=["a", "b"], baseline=["a", "b"])
+    fake = _fake_yt(FakeYouTube(title="Mix", items=["a", "b", "x"], unavailable={"x"}))
+
+    merge_playlist(db, user, pl)
+    assert parse_unavailable(pl) == {"x"}, "recorded un-ingestable on the first sync"
+
+    # 'x' is removed from the YouTube playlist entirely; the next sync must drop it.
+    fake.items = [row for row in fake.items if row[1] != "x"]
+    r2 = merge_playlist(db, user, pl)
+
+    assert r2["failures"] == []
+    assert parse_unavailable(pl) == set(), "'x' pruned once it left YouTube"

backend/tests/test_plex_last_watched_sort.py

@@ -0,0 +1,158 @@
+"""S3: the "last watched" browse sort (`sort=lastwatched`). Movies rank by
+coalesce(progress_updated_at, watched_at); shows by max(coalesce(...)) across their episodes
+(rollup.resumed_at). Never-watched titles sink to the bottom (nullslast). DB lane (`db` fixture) —
+skipped without Postgres.
+"""
+
+from datetime import datetime, timedelta, timezone
+
+from fastapi.testclient import TestClient
+
+import app.state as state
+from app.auth import current_user
+from app.db import get_db
+from app.main import app
+from app.models import PlexItem, PlexLibrary, PlexShow, PlexState, User
+
+NOW = datetime(2024, 6, 1, tzinfo=timezone.utc)
+
+
+def _seed(db):
+    lib_m = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+    lib_s = PlexLibrary(plex_key="2", title="Shows", kind="show", enabled=True)
+    db.add_all([lib_m, lib_s])
+    db.flush()
+
+    # Movies: newest resume, a watched-only (coalesce falls back to watched_at), an older resume, and a
+    # never-touched one.
+    mo_new = PlexItem(rating_key="mo_new", library_id=lib_m.id, kind="movie", title="Newest Resume")
+    mo_watched = PlexItem(
+        rating_key="mo_watched", library_id=lib_m.id, kind="movie", title="Watched Only"
+    )
+    mo_old = PlexItem(rating_key="mo_old", library_id=lib_m.id, kind="movie", title="Older Resume")
+    mo_never = PlexItem(rating_key="mo_never", library_id=lib_m.id, kind="movie", title="Never")
+
+    # Shows: a recently-resumed episode, a watched-only episode, and a never-watched show.
+    sh_recent = PlexShow(
+        rating_key="sh_recent", library_id=lib_s.id, title="Recent Show", child_count=1
+    )
+    sh_watched = PlexShow(
+        rating_key="sh_watched", library_id=lib_s.id, title="Watched Show", child_count=1
+    )
+    sh_never = PlexShow(
+        rating_key="sh_never", library_id=lib_s.id, title="Never Show", child_count=1
+    )
+    db.add_all([mo_new, mo_watched, mo_old, mo_never, sh_recent, sh_watched, sh_never])
+    db.flush()
+
+    ep_recent = PlexItem(
+        rating_key="sh_recent_e1",
+        library_id=lib_s.id,
+        kind="episode",
+        title="E1",
+        show_id=sh_recent.id,
+        season_number=1,
+        episode_number=1,
+    )
+    ep_watched = PlexItem(
+        rating_key="sh_watched_e1",
+        library_id=lib_s.id,
+        kind="episode",
+        title="E1",
+        show_id=sh_watched.id,
+        season_number=1,
+        episode_number=1,
+    )
+    db.add_all([ep_recent, ep_watched])
+
+    user = User(email="lastwatched@example.com")
+    db.add(user)
+    db.flush()
+
+    db.add_all(
+        [
+            PlexState(
+                user_id=user.id,
+                item_id=mo_new.id,
+                status="new",
+                position_seconds=100,
+                progress_updated_at=NOW,
+            ),
+            PlexState(
+                user_id=user.id,
+                item_id=mo_watched.id,
+                status="watched",
+                watched_at=NOW - timedelta(hours=1),
+            ),
+            PlexState(
+                user_id=user.id,
+                item_id=mo_old.id,
+                status="new",
+                position_seconds=100,
+                progress_updated_at=NOW - timedelta(hours=2),
+            ),
+            # Show episodes.
+            PlexState(
+                user_id=user.id,
+                item_id=ep_recent.id,
+                status="new",
+                position_seconds=50,
+                progress_updated_at=NOW - timedelta(minutes=30),
+            ),
+            PlexState(
+                user_id=user.id,
+                item_id=ep_watched.id,
+                status="watched",
+                watched_at=NOW - timedelta(minutes=90),
+            ),
+        ]
+    )
+    db.commit()
+    return user
+
+
+def _get(db, user, monkeypatch, path):
+    monkeypatch.setattr(state, "_configured_cache", True)
+    app.dependency_overrides[get_db] = lambda: db
+    app.dependency_overrides[current_user] = lambda: user
+    try:
+        return TestClient(app).get(path)
+    finally:
+        app.dependency_overrides.clear()
+
+
+def _ids(resp):
+    return [i["id"] for i in resp.json()["items"]]
+
+
+def test_movies_ordered_by_last_watched_desc(db, monkeypatch):
+    user = _seed(db)
+    resp = _get(
+        db, user, monkeypatch, "/api/plex/library?scope=movie&sort=lastwatched&sort_dir=desc"
+    )
+    assert resp.status_code == 200, resp.text
+    # Newest resume, then the watched-only (coalesce → watched_at), then the older resume, then never.
+    assert _ids(resp) == ["mo_new", "mo_watched", "mo_old", "mo_never"]
+
+
+def test_shows_ordered_by_last_watched_desc(db, monkeypatch):
+    user = _seed(db)
+    resp = _get(
+        db, user, monkeypatch, "/api/plex/library?scope=show&sort=lastwatched&sort_dir=desc"
+    )
+    assert resp.status_code == 200, resp.text
+    # Recent resume first, then the watched-only show, then the never-watched one (nullslast).
+    assert _ids(resp) == ["sh_recent", "sh_watched", "sh_never"]
+
+
+def test_last_watched_mixed_scope_nullslast(db, monkeypatch):
+    user = _seed(db)
+    resp = _get(
+        db, user, monkeypatch, "/api/plex/library?scope=both&sort=lastwatched&sort_dir=desc"
+    )
+    assert resp.status_code == 200, resp.text
+    ids = _ids(resp)
+    # Global recency order across both legs: mo_new (NOW) > sh_recent (−30m) > mo_watched (−1h) >
+    # sh_watched (−90m) > mo_old (−2h); the two never-watched titles sink to the bottom.
+    assert ids[:5] == ["mo_new", "sh_recent", "mo_watched", "sh_watched", "mo_old"]
+    assert set(ids[5:]) == {"mo_never", "sh_never"}

backend/tests/test_plex_playback_class.py

@@ -0,0 +1,495 @@
+"""The playback-class filter (E7): filter the Plex feed by Direct Play / Direct Stream / Transcode·HW /
+Transcode·SW. Covers the shared classifier + Stream parsing (unit), the sync derivation + codec-change
+reset, the bit-depth backfill, and the /library filter + /facets counts (DB lane).
+
+The HW/SW split is derived from the stored `transcode_hw` facet (codec at sync, refined by the bit-depth
+backfill). These tests pin that a 10-bit/HDR HEVC lands in SW even though its codec is HW-decodable —
+the exact case the runtime VAAPI path (plex.stream) also special-cases.
+"""
+
+import re
+from pathlib import Path
+
+import app.state as state
+from app.auth import current_user
+from app.db import get_db
+from app.main import app
+from app.models import PlexItem, PlexLibrary, User
+from app.plex import sync
+from fastapi.testclient import TestClient
+
+
+class TestTranscodeHwCapable:
+    """The single classifier both the catalog facet and (by codec) the runtime encoder choice key off."""
+
+    def test_non_transcode_items_are_none(self):
+        assert sync.transcode_hw_capable("direct", "h264") is None
+        assert sync.transcode_hw_capable("remux", "h264") is None
+        assert sync.transcode_hw_capable(None, "hevc") is None
+
+    def test_hw_decodable_8bit_sdr_is_hw(self):
+        assert sync.transcode_hw_capable("transcode", "hevc") is True
+        assert sync.transcode_hw_capable("transcode", "vp9", bit_depth=8) is True
+
+    def test_non_decodable_codec_is_sw(self):
+        # AV1 / MPEG-4 ASP (XviD) can't be HW-decoded on Gen 9.5 → software regardless of bit depth.
+        assert sync.transcode_hw_capable("transcode", "av1") is False
+        assert sync.transcode_hw_capable("transcode", "mpeg4", bit_depth=8) is False
+
+    def test_10bit_or_hdr_hevc_is_sw(self):
+        # A HW-decodable codec that is 10-bit or HDR still breaks the VAAPI nv12 pipeline → software.
+        assert sync.transcode_hw_capable("transcode", "hevc", bit_depth=10) is False
+        assert sync.transcode_hw_capable("transcode", "hevc", bit_depth=8, hdr=True) is False
+
+
+class TestVideoStreamProps:
+    def test_reads_bit_depth_and_hdr_from_the_video_stream(self):
+        meta = {
+            "Media": [
+                {
+                    "Part": [
+                        {
+                            "Stream": [
+                                {"streamType": 2, "codec": "eac3"},  # audio — skipped
+                                {"streamType": 1, "bitDepth": 10, "colorTrc": "smpte2084"},
+                            ]
+                        }
+                    ]
+                }
+            ]
+        }
+        assert sync._video_stream_props(meta) == (10, True)
+
+    def test_8bit_sdr_stream(self):
+        meta = {"Media": [{"Part": [{"Stream": [{"streamType": 1, "bitDepth": 8}]}]}]}
+        assert sync._video_stream_props(meta) == (8, False)
+
+    def test_absent_stream_is_none_false(self):
+        assert sync._video_stream_props({}) == (None, False)
+        assert sync._video_stream_props({"Media": [{"Part": [{}]}]}) == (None, False)
+
+
+class TestSyncDerivation:
+    """`_apply_item` sets transcode_hw codec-only at sync (bit depth unknown from the listing), and a
+    changed video codec resets the probe watermark so a stale bit-depth can't linger."""
+
+    def _meta(self, vcodec, *, key="/parts/1/file.mkv", file="/m.mkv"):
+        return {
+            "title": "X",
+            "Media": [{"videoCodec": vcodec, "Part": [{"file": file, "key": key}]}],
+        }
+
+    def test_codec_only_derivation_at_sync(self):
+        row = PlexItem(rating_key="x", kind="movie")
+        sync._apply_item(row, lib_id=1, kind="movie", meta=self._meta("hevc"))
+        assert row.playable == "transcode" and row.transcode_hw is True  # decodable, 8-bit assumed
+        row2 = PlexItem(rating_key="y", kind="movie")
+        sync._apply_item(row2, lib_id=1, kind="movie", meta=self._meta("av1"))
+        assert row2.transcode_hw is False  # av1 not HW-decodable
+
+    def test_probed_value_survives_resync_when_codec_unchanged(self):
+        row = PlexItem(rating_key="x", kind="movie")
+        sync._apply_item(row, lib_id=1, kind="movie", meta=self._meta("hevc"))
+        # Simulate the backfill downgrading this 10-bit HEVC to software.
+        row.transcode_hw = False
+        row.video_bit_depth = 10
+        row.media_probed_at = sync.datetime.now(sync.timezone.utc)
+        sync._apply_item(row, lib_id=1, kind="movie", meta=self._meta("hevc"))
+        assert row.transcode_hw is False  # NOT re-derived back to True
+        assert row.video_bit_depth == 10 and row.media_probed_at is not None
+
+    def test_codec_change_resets_the_probe(self):
+        row = PlexItem(rating_key="x", kind="movie")
+        sync._apply_item(row, lib_id=1, kind="movie", meta=self._meta("hevc"))
+        row.transcode_hw = False
+        row.video_bit_depth = 10
+        row.media_probed_at = sync.datetime.now(sync.timezone.utc)
+        # The file was replaced with an h264 remux — the stale 10-bit probe must be cleared.
+        sync._apply_item(row, lib_id=1, kind="movie", meta=self._meta("h264"))
+        assert row.video_bit_depth is None and row.media_probed_at is None
+
+    def test_same_codec_reencode_with_a_new_part_resets_the_probe(self):
+        # A same-codec bit-depth re-encode (e.g. 8-bit→10-bit HEVC) keeps codec 'hevc' but replaces the
+        # physical file, so its Plex Part key changes. Codec-only reset would miss this and keep the stale
+        # 8-bit/HW verdict forever (the backfill only re-probes media_probed_at IS NULL rows) — the
+        # part-key move must reset the watermark so the new bit depth is re-probed.
+        row = PlexItem(rating_key="x", kind="movie")
+        sync._apply_item(row, lib_id=1, kind="movie", meta=self._meta("hevc", key="/parts/1/f.mkv"))
+        row.transcode_hw = True
+        row.video_bit_depth = 8
+        row.media_probed_at = sync.datetime.now(sync.timezone.utc)
+        # Re-encoded in place: same codec 'hevc', but a new Part key (new file).
+        sync._apply_item(row, lib_id=1, kind="movie", meta=self._meta("hevc", key="/parts/2/f.mkv"))
+        assert row.video_bit_depth is None and row.media_probed_at is None  # re-probe scheduled
+
+
+def test_migration_codec_set_matches_hw_decodable_codecs():
+    # Migration 0077 hardcodes the HW-decodable codec set in raw SQL and its comment mandates it stay
+    # identical to plex.sync.HW_DECODABLE_CODECS. A comment isn't enforcement (house rule) — pin the
+    # equality so adding/removing a codec from the frozenset without editing the migration fails here
+    # (else already-migrated prod rows keep a wrong transcode_hw the runtime derivation wouldn't catch).
+    mig = (
+        Path(__file__).resolve().parent.parent
+        / "alembic"
+        / "versions"
+        / "0077_plex_playback_class.py"
+    )
+    m = re.search(r"lower\(codec_video\)\s+IN\s+\(([^)]*)\)", mig.read_text())
+    assert m, "could not find the codec IN(...) list in migration 0077"
+    codecs = {c.strip().strip("'\"").lower() for c in m.group(1).split(",")}
+    assert codecs == {c.lower() for c in sync.HW_DECODABLE_CODECS}
+
+
+class _FakePlex:
+    """Stands in for PlexClient.metadata — returns a canned full-metadata dict per rating_key."""
+
+    def __init__(self, by_key):
+        self.by_key = by_key
+
+    def metadata(self, rating_key, markers=False):
+        return self.by_key.get(rating_key)
+
+
+def test_probe_media_batch_refines_hw_to_sw_for_10bit(db):
+    lib = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+    db.add(lib)
+    db.flush()
+    hevc8 = PlexItem(
+        rating_key="h8",
+        library_id=lib.id,
+        kind="movie",
+        title="8bit",
+        playable="transcode",
+        codec_video="hevc",
+        transcode_hw=True,
+    )
+    hevc10 = PlexItem(
+        rating_key="h10",
+        library_id=lib.id,
+        kind="movie",
+        title="10bit",
+        playable="transcode",
+        codec_video="hevc",
+        transcode_hw=True,
+    )
+    xvid = PlexItem(
+        rating_key="xv",
+        library_id=lib.id,
+        kind="movie",
+        title="xvid",
+        playable="transcode",
+        codec_video="mpeg4",
+        transcode_hw=False,
+    )
+    db.add_all([hevc8, hevc10, xvid])
+    db.commit()
+    plex = _FakePlex(
+        {
+            "h8": {"Media": [{"Part": [{"Stream": [{"streamType": 1, "bitDepth": 8}]}]}]},
+            "h10": {"Media": [{"Part": [{"Stream": [{"streamType": 1, "bitDepth": 10}]}]}]},
+        }
+    )
+    probed = sync._probe_media_batch(db, plex)
+    db.refresh(hevc8)
+    db.refresh(hevc10)
+    db.refresh(xvid)
+    # Only the two HW-decodable HEVC items are probed; the XviD is SW-by-codec and never fetched.
+    assert probed == 2
+    assert hevc8.video_bit_depth == 8 and hevc8.transcode_hw is True and hevc8.media_probed_at
+    assert hevc10.video_bit_depth == 10 and hevc10.transcode_hw is False  # downgraded to software
+    assert xvid.media_probed_at is None  # not in the work-list
+    # A second run has nothing left to do (watermarks set).
+    assert sync._probe_media_batch(db, plex) == 0
+
+
+def test_probe_stamps_even_when_plex_has_no_stream(db):
+    lib = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+    db.add(lib)
+    db.flush()
+    item = PlexItem(
+        rating_key="ns",
+        library_id=lib.id,
+        kind="movie",
+        title="nostream",
+        playable="transcode",
+        codec_video="hevc",
+        transcode_hw=True,
+    )
+    db.add(item)
+    db.commit()
+    plex = _FakePlex({"ns": {"Media": [{"Part": [{}]}]}})  # no Stream array
+    assert sync._probe_media_batch(db, plex) == 1
+    db.refresh(item)
+    # Probed (watermark set so it isn't re-fetched forever); bit depth unknown → stays codec-HW.
+    assert item.media_probed_at is not None and item.video_bit_depth is None
+    assert item.transcode_hw is True
+
+
+def test_probe_media_batch_is_bounded_and_oldest_first(db):
+    # The per-run bound (limit) caps Plex load; oldest-id-first means successive runs cover the whole
+    # backlog without starving any item. Seed 3 eligible items, probe with limit=2.
+    lib = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+    db.add(lib)
+    db.flush()
+    items = [
+        PlexItem(
+            rating_key=f"h{i}",
+            library_id=lib.id,
+            kind="movie",
+            title=f"m{i}",
+            playable="transcode",
+            codec_video="hevc",
+            transcode_hw=True,
+        )
+        for i in range(3)
+    ]
+    db.add_all(items)  # inserted in order → ascending ids
+    db.commit()
+    plex = _FakePlex(
+        {
+            f"h{i}": {"Media": [{"Part": [{"Stream": [{"streamType": 1, "bitDepth": 8}]}]}]}
+            for i in range(3)
+        }
+    )
+    assert sync._probe_media_batch(db, plex, limit=2) == 2  # exactly the bound
+    for it in items:
+        db.refresh(it)
+    # The two LOWEST-id rows were probed; the third waits for the next run.
+    assert items[0].media_probed_at is not None and items[1].media_probed_at is not None
+    assert items[2].media_probed_at is None
+    # The next run continues with the remaining item.
+    assert sync._probe_media_batch(db, plex, limit=2) == 1
+    db.refresh(items[2])
+    assert items[2].media_probed_at is not None
+
+
+class _RaisingPlex:
+    """metadata() raises for `bad_key`, returns a canned dict otherwise — to exercise the transient
+    fetch-failure branch (leave the watermark NULL so the item retries next run)."""
+
+    def __init__(self, by_key, bad_key):
+        self.by_key = by_key
+        self.bad_key = bad_key
+
+    def metadata(self, rating_key, markers=False):
+        if rating_key == self.bad_key:
+            raise RuntimeError("plex timeout")
+        return self.by_key.get(rating_key)
+
+
+def test_probe_media_batch_leaves_a_transient_failure_unstamped_to_retry(db):
+    lib = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+    db.add(lib)
+    db.flush()
+    good = PlexItem(
+        rating_key="g",
+        library_id=lib.id,
+        kind="movie",
+        title="good",
+        playable="transcode",
+        codec_video="hevc",
+        transcode_hw=True,
+    )
+    bad = PlexItem(
+        rating_key="b",
+        library_id=lib.id,
+        kind="movie",
+        title="bad",
+        playable="transcode",
+        codec_video="hevc",
+        transcode_hw=True,
+    )
+    db.add_all([good, bad])
+    db.commit()
+    plex = _RaisingPlex(
+        {"g": {"Media": [{"Part": [{"Stream": [{"streamType": 1, "bitDepth": 10}]}]}]}}, bad_key="b"
+    )
+    # The raise on 'b' must not abort the batch: 'g' is still probed and counted; 'b' stays NULL.
+    assert sync._probe_media_batch(db, plex) == 1
+    db.refresh(good)
+    db.refresh(bad)
+    assert good.media_probed_at is not None and good.transcode_hw is False  # 10-bit → SW
+    assert bad.media_probed_at is None  # transient failure → retried next run, not stamped
+
+
+def _seed_classes(db):
+    lib = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+    db.add(lib)
+    db.flush()
+    db.add_all(
+        [
+            PlexItem(
+                rating_key="d1", library_id=lib.id, kind="movie", title="Direct", playable="direct"
+            ),
+            PlexItem(
+                rating_key="r1", library_id=lib.id, kind="movie", title="Remux", playable="remux"
+            ),
+            PlexItem(
+                rating_key="thw",
+                library_id=lib.id,
+                kind="movie",
+                title="HW",
+                playable="transcode",
+                codec_video="hevc",
+                transcode_hw=True,
+            ),
+            PlexItem(
+                rating_key="tsw",
+                library_id=lib.id,
+                kind="movie",
+                title="SW",
+                playable="transcode",
+                codec_video="mpeg4",
+                transcode_hw=False,
+            ),
+        ]
+    )
+    return lib
+
+
+def _client(db, user, monkeypatch):
+    monkeypatch.setattr(state, "_configured_cache", True)
+    app.dependency_overrides[get_db] = lambda: db
+    app.dependency_overrides[current_user] = lambda: user
+    return TestClient(app)
+
+
+def test_library_filters_by_playback_class(db, monkeypatch):
+    _seed_classes(db)
+    user = User(email="pclass@example.com")
+    db.add(user)
+    db.commit()
+    client = _client(db, user, monkeypatch)
+    try:
+        # Software-only transcodes.
+        sw = client.get("/api/plex/library?scope=movie&playable=transcode_sw")
+        assert sw.status_code == 200, sw.text
+        assert {i["id"] for i in sw.json()["items"]} == {"tsw"}
+        # HW transcode + Direct Play, OR-combined.
+        both = client.get("/api/plex/library?scope=movie&playable=transcode_hw,direct")
+        assert {i["id"] for i in both.json()["items"]} == {"thw", "d1"}
+        # The HW card carries the transcode_hw flag for the 4-way badge.
+        card = next(i for i in both.json()["items"] if i["id"] == "thw")
+        assert card["transcode_hw"] is True
+        # No filter → everything.
+        allm = client.get("/api/plex/library?scope=movie")
+        assert {i["id"] for i in allm.json()["items"]} == {"d1", "r1", "thw", "tsw"}
+    finally:
+        app.dependency_overrides.clear()
+
+
+def test_facets_count_playback_classes_in_severity_order(db, monkeypatch):
+    _seed_classes(db)
+    user = User(email="pclassfacet@example.com")
+    db.add(user)
+    db.commit()
+    client = _client(db, user, monkeypatch)
+    try:
+        resp = client.get("/api/plex/facets?scope=movie")
+    finally:
+        app.dependency_overrides.clear()
+    assert resp.status_code == 200, resp.text
+    playable = resp.json()["playable"]
+    # Fixed good→heavy order (not by count), one per seeded class.
+    assert [p["value"] for p in playable] == ["direct", "remux", "transcode_hw", "transcode_sw"]
+    assert {p["value"]: p["count"] for p in playable} == {
+        "direct": 1,
+        "remux": 1,
+        "transcode_hw": 1,
+        "transcode_sw": 1,
+    }
+
+
+def test_unprobed_transcode_folds_into_sw(db, monkeypatch):
+    # transcode_hw NULL is the COMMON initial state (before the bit-depth backfill runs). The query's
+    # CASE has no explicit NULL arm — it relies on the `playable=='transcode'` else folding NULL in with
+    # software. Pin that fold for BOTH the filter and the facet, so a reorder can't silently drop the
+    # item from the feed (an honest-state violation).
+    lib = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+    db.add(lib)
+    db.flush()
+    db.add(
+        PlexItem(
+            rating_key="tnull",
+            library_id=lib.id,
+            kind="movie",
+            title="Unprobed",
+            playable="transcode",
+            codec_video="hevc",
+            transcode_hw=None,
+        )
+    )
+    user = User(email="pnull@example.com")
+    db.add(user)
+    db.commit()
+    client = _client(db, user, monkeypatch)
+    try:
+        sw = client.get("/api/plex/library?scope=movie&playable=transcode_sw")
+        assert {i["id"] for i in sw.json()["items"]} == {"tnull"}  # NULL → SW bucket
+        hw = client.get("/api/plex/library?scope=movie&playable=transcode_hw")
+        assert hw.json()["items"] == []  # never HW
+        facets = client.get("/api/plex/facets?scope=movie")
+        counts = {p["value"]: p["count"] for p in facets.json()["playable"]}
+        assert counts.get("transcode_sw") == 1 and counts.get("transcode_hw", 0) == 0
+    finally:
+        app.dependency_overrides.clear()
+
+
+def test_facet_playable_self_excludes_the_active_selection(db, monkeypatch):
+    # A selected playable class must NOT narrow the playable facet's OWN counts (facet self-exclusion),
+    # otherwise picking one class would collapse the list and you couldn't OR-add a second. Selecting
+    # 'direct' must still return all four classes at their full, unnarrowed counts.
+    _seed_classes(db)
+    user = User(email="pself@example.com")
+    db.add(user)
+    db.commit()
+    client = _client(db, user, monkeypatch)
+    try:
+        resp = client.get("/api/plex/facets?scope=movie&playable=direct")
+    finally:
+        app.dependency_overrides.clear()
+    assert resp.status_code == 200, resp.text
+    counts = {p["value"]: p["count"] for p in resp.json()["playable"]}
+    assert counts == {"direct": 1, "remux": 1, "transcode_hw": 1, "transcode_sw": 1}
+
+
+def test_active_playable_narrows_the_other_facets(db, monkeypatch):
+    # The flip side of self-exclusion: an active playable class DOES narrow the OTHER facet groups (so
+    # e.g. the year range reflects only the selected class). Seed a Direct movie (2000) and a
+    # software-transcode movie (2020); selecting playable=direct must collapse the year facet to 2000.
+    lib = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+    db.add(lib)
+    db.flush()
+    db.add_all(
+        [
+            PlexItem(
+                rating_key="d2000",
+                library_id=lib.id,
+                kind="movie",
+                title="Direct2000",
+                playable="direct",
+                year=2000,
+            ),
+            PlexItem(
+                rating_key="s2020",
+                library_id=lib.id,
+                kind="movie",
+                title="SW2020",
+                playable="transcode",
+                codec_video="mpeg4",
+                transcode_hw=False,
+                year=2020,
+            ),
+        ]
+    )
+    user = User(email="pnarrow@example.com")
+    db.add(user)
+    db.commit()
+    client = _client(db, user, monkeypatch)
+    try:
+        wide = client.get("/api/plex/facets?scope=movie").json()
+        narrow = client.get("/api/plex/facets?scope=movie&playable=direct").json()
+    finally:
+        app.dependency_overrides.clear()
+    assert (wide["year_min"], wide["year_max"]) == (2000, 2020)  # both classes span the range
+    assert (narrow["year_min"], narrow["year_max"]) == (2000, 2000)  # narrowed to the Direct subset

backend/tests/test_plex_playback_session.py

@@ -0,0 +1,107 @@
+"""The playback-session route's mode routing (E6 S1b).
+
+`POST /stream/{rk}/session` is the single switch that decides how an item plays: a browser-native
+file is served raw (`mode:"direct"`), everything else (re)starts an HLS session — and a
+`playable="transcode"` item (non-h264: HEVC/VP9/AV1/…) must take that HLS path with the video
+RE-ENCODED, not stream-copied. That routing replaced a former `HTTP 501`, and the only thing that
+tells `start_session` to re-encode is the `transcode=` flag this route derives from `it.playable`.
+The command-builder itself is unit-tested in `test_plex_stream.py`; here we pin the ROUTE decision
+(no ffmpeg spawned — `start_session` is stubbed to echo the flag it was handed).
+
+DB lane (`db` fixture) — skipped when no Postgres is reachable.
+"""
+
+from types import SimpleNamespace
+
+from fastapi.testclient import TestClient
+
+import app.state as state
+from app.auth import current_user
+from app.db import get_db
+from app.main import app
+from app.models import PlexItem, PlexLibrary, User
+from app.plex import paths as plex_paths
+from app.plex import stream as plex_stream
+
+
+def _item(db, *, playable, rating_key="m1"):
+    lib = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+    db.add(lib)
+    db.flush()
+    it = PlexItem(
+        rating_key=rating_key,
+        library_id=lib.id,
+        kind="movie",
+        title="A Movie",
+        file_path="/media/a.mkv",
+        playable=playable,
+    )
+    db.add(it)
+    db.commit()
+    return it
+
+
+def _user(db, email="play@example.com"):
+    u = User(email=email)
+    db.add(u)
+    db.flush()
+    return u
+
+
+def _post(db, user, monkeypatch, rating_key, *, captured):
+    """Drive the endpoint with ffmpeg stubbed out. `start_session` records the `transcode` flag it
+    was called with into `captured` and returns a stand-in session echoing it back."""
+    monkeypatch.setattr(state, "_configured_cache", True)  # pass the request gate
+    monkeypatch.setattr(plex_stream, "reap_idle", lambda: None)
+    monkeypatch.setattr(plex_paths, "local_media_path", lambda db_, fp: "/local/a.mkv")
+
+    def fake_start(db_, it, start, audio, aoff, multi, transcode=False):
+        captured["transcode"] = transcode
+        return SimpleNamespace(
+            media_start_s=start, entry="index.m3u8", transcode=transcode, hw=False, tonemap=False
+        )
+
+    monkeypatch.setattr(plex_stream, "start_session", fake_start)
+    app.dependency_overrides[get_db] = lambda: db
+    app.dependency_overrides[current_user] = lambda: user
+    try:
+        return TestClient(app).post(f"/api/plex/stream/{rating_key}/session")
+    finally:
+        app.dependency_overrides.clear()
+
+
+def test_transcode_item_routes_to_an_hls_reencode_session(db, monkeypatch):
+    # A non-h264 item (formerly HTTP 501) now plays: mode=hls, transcode=True threaded to start_session.
+    it = _item(db, playable="transcode")
+    user = _user(db)
+    captured: dict = {}
+    resp = _post(db, user, monkeypatch, it.rating_key, captured=captured)
+    assert resp.status_code == 200, resp.text
+    body = resp.json()
+    assert body["mode"] == "hls"
+    assert body["transcode"] is True
+    assert captured["transcode"] is True  # start_session was told to re-encode
+
+
+def test_remux_item_stays_a_stream_copy_session(db, monkeypatch):
+    # A remux (h264) item takes the SAME HLS path but must NOT re-encode.
+    it = _item(db, playable="remux", rating_key="m2")
+    user = _user(db, "remux@example.com")
+    captured: dict = {}
+    resp = _post(db, user, monkeypatch, it.rating_key, captured=captured)
+    assert resp.status_code == 200, resp.text
+    body = resp.json()
+    assert body["mode"] == "hls"
+    assert body["transcode"] is False
+    assert captured["transcode"] is False
+
+
+def test_direct_item_never_opens_a_session(db, monkeypatch):
+    # A browser-native file is served raw — start_session is never reached, so no transcode decision.
+    it = _item(db, playable="direct", rating_key="m3")
+    user = _user(db, "direct@example.com")
+    captured: dict = {}
+    resp = _post(db, user, monkeypatch, it.rating_key, captured=captured)
+    assert resp.status_code == 200, resp.text
+    assert resp.json()["mode"] == "direct"
+    assert "transcode" not in captured  # start_session not called

backend/tests/test_plex_stream.py

@@ -8,6 +8,7 @@ Since the sweep stopped being awaited at startup it also runs CONCURRENTLY with
 second half of this file pins what keeps it off a LIVE session's segments."""
 
 import os
+from pathlib import Path
 
 import pytest
 
@@ -154,3 +155,716 @@ class TestSweepOrphans:
         os.utime(f, (f.stat().st_mtime - 3600,) * 2)  # old enough that only is_dir() saves it
         assert stream.sweep_orphans(older_than=_cutoff(hls_root)) == 0
         assert f.exists()
+
+
+class _FakeProc:
+    """Stand-in for the ffmpeg Popen — start_session only stores it (and _kill/reap poll it later)."""
+
+    def poll(self):
+        return None
+
+
+class _FakeItem:
+    def __init__(self, rating_key="12345", file_path="/media/movie.mkv", codec_video="h264"):
+        self.rating_key = rating_key
+        self.file_path = file_path
+        self.playable = "remux"
+        self.codec_video = codec_video
+
+
+class _CapturingProc:
+    """Records the argv + kwargs each Popen was called with, then behaves like the ffmpeg proc."""
+
+    calls: list[tuple] = []
+
+    def __init__(self, *args, **kwargs):
+        _CapturingProc.calls.append((args, kwargs))
+
+    def poll(self):
+        return None
+
+
+def _venc(cmd):
+    """The video codec ffmpeg was told to use (the value after the first `-c:v`)."""
+    return cmd[cmd.index("-c:v") + 1]
+
+
+class TestTranscodeCommand:
+    """The transcode video re-encode (playable='transcode'): the SAME HLS command as remux with the
+    video encoder swapped in for `-c:v copy`. The HW path can only be exercised on prod (VAAPI needs
+    Linux + Intel /dev/dri), so its SHAPE is pinned here; the software path is the one UAT'd locally."""
+
+    SRC = Path("/media/movie.mkv")
+    OUT = Path("/out")
+
+    def test_remux_still_stream_copies_the_video(self):
+        cmd = stream._ffmpeg_cmd(self.SRC, 0.0, self.OUT, None)
+        assert _venc(cmd) == "copy"
+        assert "libx264" not in cmd and "h264_vaapi" not in cmd
+        assert "-hwaccel" not in cmd  # no GPU decode on the copy path
+        assert "-force_key_frames" not in cmd  # copy leans on the source's own keyframes
+
+    def test_software_transcode_uses_libx264_and_mints_keyframes(self):
+        cmd = stream._ffmpeg_cmd(self.SRC, 0.0, self.OUT, None, transcode=True, hw=False)
+        assert _venc(cmd) == "libx264"
+        assert "copy" not in cmd  # the video is no longer stream-copied
+        # 8-bit High (yuv420p), not High10, so any browser decodes a 10-bit HEVC source.
+        assert cmd[cmd.index("-pix_fmt") + 1] == "yuv420p"
+        assert "-threads" in cmd  # a core reserved for request handling / playback
+        assert "-hwaccel" not in cmd  # software path: CPU decode, no render node needed
+        # A forced keyframe at every segment boundary so the HLS muxer cuts independent segments.
+        assert (
+            cmd[cmd.index("-force_key_frames") + 1] == f"expr:gte(t,n_forced*{stream._SEG_SECONDS})"
+        )
+
+    def test_hardware_transcode_uses_the_full_vaapi_pipeline(self):
+        cmd = stream._ffmpeg_cmd(self.SRC, 0.0, self.OUT, None, transcode=True, hw=True)
+        assert _venc(cmd) == "h264_vaapi"
+        assert "libx264" not in cmd
+        # GPU decode options must precede the input so the source is decoded on-device.
+        assert cmd[cmd.index("-hwaccel") + 1] == "vaapi"
+        assert "-hwaccel_output_format" in cmd
+        assert cmd[cmd.index("-vaapi_device") + 1] == stream._VAAPI_DEVICE
+        assert cmd.index("-hwaccel") < cmd.index("-i")
+        # scale_vaapi=format=nv12 downconverts a 10-bit source to 8-bit nv12 for h264_vaapi.
+        assert "scale_vaapi=format=nv12" in cmd
+        assert (
+            cmd[cmd.index("-force_key_frames") + 1] == f"expr:gte(t,n_forced*{stream._SEG_SECONDS})"
+        )
+
+    def test_multi_audio_transcode_reencodes_the_video_variant(self):
+        cmd = stream._ffmpeg_cmd(
+            self.SRC, 0.0, self.OUT, None, audio_langs=["eng", "hun"], transcode=True, hw=False
+        )
+        assert _venc(cmd) == "libx264"  # video re-encoded…
+        assert "-var_stream_map" in cmd  # …but still multi-rendition (client-side audio switch)
+        assert "copy" not in cmd
+
+    def test_software_preset_and_crf_come_from_the_knobs(self):
+        cmd = stream._ffmpeg_cmd(
+            self.SRC, 0.0, self.OUT, None, transcode=True, hw=False, preset="slow", crf=18
+        )
+        assert cmd[cmd.index("-preset") + 1] == "slow"
+        assert cmd[cmd.index("-crf") + 1] == "18"
+
+    def test_software_max_height_caps_with_a_downscale_only_filter(self):
+        cmd = stream._ffmpeg_cmd(
+            self.SRC, 0.0, self.OUT, None, transcode=True, hw=False, max_height=720
+        )
+        # Downscale-only, aspect-preserving, even width; the comma in min() escaped so it's ONE filter.
+        assert cmd[cmd.index("-vf") + 1] == "scale=-2:min(ih\\,720)"
+
+    def test_software_max_height_zero_means_no_scale_filter(self):
+        cmd = stream._ffmpeg_cmd(
+            self.SRC, 0.0, self.OUT, None, transcode=True, hw=False, max_height=0
+        )
+        assert "-vf" not in cmd  # source resolution kept
+
+    def test_hardware_ignores_max_height(self):
+        # The GPU encode is cheap, so it runs at source resolution; max_height is a software-only knob.
+        cmd = stream._ffmpeg_cmd(
+            self.SRC, 0.0, self.OUT, None, transcode=True, hw=True, max_height=720
+        )
+        assert cmd[cmd.index("-vf") + 1] == "scale_vaapi=format=nv12"  # not a software scale
+
+    def test_hdr_tonemap_uses_the_opencl_graph(self):
+        # The HDR/10-bit HW path: VAAPI decode → OpenCL tonemap → VAAPI encode. Gen 9.5 can't tonemap in
+        # the VAAPI VPP, so this is the only HW route for a 10-bit/HDR source.
+        cmd = stream._ffmpeg_cmd(
+            self.SRC, 0.0, self.OUT, None, transcode=True, hw=True, tonemap=True
+        )
+        assert _venc(cmd) == "h264_vaapi"
+        assert "libx264" not in cmd
+        # Named devices + an OpenCL device DERIVED from the VAAPI one, all before -i.
+        assert cmd[cmd.index("-init_hw_device") + 1] == f"vaapi=va:{stream._VAAPI_DEVICE}"
+        assert "opencl=ocl@va" in cmd
+        assert cmd[cmd.index("-hwaccel_device") + 1] == "va"
+        assert cmd.index("-init_hw_device") < cmd.index("-i")
+        # The filter graph runs on the derived OpenCL device and tone-maps HDR→SDR to 8-bit nv12.
+        assert cmd[cmd.index("-filter_hw_device") + 1] == "ocl"
+        vf = cmd[cmd.index("-vf") + 1]
+        assert "hwmap=derive_device=opencl" in vf
+        assert "tonemap_opencl=" in vf and "format=nv12" in vf
+        assert "hwmap=derive_device=vaapi:reverse=1" in vf
+        assert "scale_vaapi" not in vf  # the plain 8-bit path's filter must NOT be used here
+        assert (
+            cmd[cmd.index("-force_key_frames") + 1] == f"expr:gte(t,n_forced*{stream._SEG_SECONDS})"
+        )
+
+
+class TestWantHw:
+    """VAAPI is used only where the render node was passed in AND (in auto) the source is HW-decodable,
+    with an admin `plex_transcode_hw` policy (auto/on/off) on top. A HW session on a 10-bit/HDR source
+    tone-maps on the GPU via OpenCL (tonemap=True) when the OpenCL runtime is present, else drops to
+    software — see the `_select_encode` cases below."""
+
+    SRC = Path("/media/movie.mkv")
+
+    @staticmethod
+    def _policy(monkeypatch, mode):
+        monkeypatch.setattr(stream.sysconfig, "get_str", lambda db, k: mode)
+
+    @staticmethod
+    def _kind(monkeypatch, kind):
+        # Pin the source classifier so the tests don't shell out to ffprobe. `kind` is one of
+        # stream._VK_HWSAFE / _VK_HDR / _VK_SDR10.
+        monkeypatch.setattr(stream, "_probe_video_kind", lambda src: kind)
+
+    @staticmethod
+    def _hwsafe(monkeypatch, safe):
+        # Back-compat convenience for the hw-gate tests that only care about 8-bit-SDR vs not: True →
+        # _VK_HWSAFE, False → _VK_SDR10 (a non-HDR non-hwsafe class, so the hw half still resolves).
+        monkeypatch.setattr(
+            stream, "_probe_video_kind", lambda src: stream._VK_HWSAFE if safe else stream._VK_SDR10
+        )
+
+    @staticmethod
+    def _opencl(monkeypatch, present):
+        # Pin the OpenCL-runtime probe so the routing doesn't depend on the CI box's /etc/OpenCL.
+        monkeypatch.setattr(stream, "_opencl_present", lambda: present)
+
+    def test_no_hw_when_not_transcoding(self, monkeypatch):
+        self._policy(monkeypatch, "auto")
+        monkeypatch.setattr(stream, "_render_node_present", lambda: True)
+        assert (
+            stream._want_hw(None, _FakeItem(codec_video="hevc"), transcode=False, src=self.SRC)
+            is False
+        )
+
+    def test_no_hw_without_a_render_node(self, monkeypatch):
+        self._policy(monkeypatch, "auto")
+        monkeypatch.setattr(stream, "_render_node_present", lambda: False)
+        assert (
+            stream._want_hw(None, _FakeItem(codec_video="hevc"), transcode=True, src=self.SRC)
+            is False
+        )
+
+    def test_auto_uses_hw_for_a_decodable_8bit_source_with_the_render_node(self, monkeypatch):
+        self._policy(monkeypatch, "auto")
+        self._hwsafe(monkeypatch, True)
+        monkeypatch.setattr(stream, "_render_node_present", lambda: True)
+        assert (
+            stream._want_hw(None, _FakeItem(codec_video="hevc"), transcode=True, src=self.SRC)
+            is True
+        )
+
+    def test_auto_falls_back_to_software_for_a_non_decodable_source(self, monkeypatch):
+        # AV1 / MPEG-4 ASP (XviD) aren't decodable on Gen 9.5 → the GPU can't feed its own encoder.
+        self._policy(monkeypatch, "auto")
+        self._hwsafe(monkeypatch, True)  # decodability gate must fire BEFORE the probe
+        monkeypatch.setattr(stream, "_render_node_present", lambda: True)
+        assert (
+            stream._want_hw(None, _FakeItem(codec_video="av1"), transcode=True, src=self.SRC)
+            is False
+        )
+        assert (
+            stream._want_hw(None, _FakeItem(codec_video="mpeg4"), transcode=True, src=self.SRC)
+            is False
+        )
+
+    def test_auto_hdr_source_falls_back_to_software_without_opencl(self, monkeypatch):
+        # A decodable HEVC that is true-HDR (PQ/HLG) can't use scale_vaapi=format=nv12 (Gen 9.5), and with
+        # no OpenCL runtime to tonemap on the GPU it drops to software libx264 (BUG 1's behaviour).
+        self._policy(monkeypatch, "auto")
+        self._kind(monkeypatch, stream._VK_HDR)
+        self._opencl(monkeypatch, False)
+        monkeypatch.setattr(stream, "_render_node_present", lambda: True)
+        assert stream._select_encode(
+            None, _FakeItem(codec_video="hevc"), transcode=True, src=self.SRC
+        ) == (False, False)
+
+    def test_auto_hdr_source_uses_hw_tonemap_with_opencl(self, monkeypatch):
+        # With the OpenCL runtime present, a true-HDR HEVC tone-maps on the GPU (VAAPI decode → OpenCL
+        # tonemap → VAAPI encode) instead of dropping to CPU — the HW HDR path.
+        self._policy(monkeypatch, "auto")
+        self._kind(monkeypatch, stream._VK_HDR)
+        self._opencl(monkeypatch, True)
+        monkeypatch.setattr(stream, "_render_node_present", lambda: True)
+        assert stream._select_encode(
+            None, _FakeItem(codec_video="hevc"), transcode=True, src=self.SRC
+        ) == (True, True)
+
+    def test_auto_10bit_SDR_source_uses_software_not_tonemap(self, monkeypatch):
+        # F1 regression: a 10-bit *SDR* (bt709) source is NOT HDR, so it must NOT get the hable HDR tone
+        # curve even when the OpenCL runtime is present — that would visibly alter an SDR picture. It takes
+        # software libx264 (an exact 10→8-bit downconvert), never (True, True).
+        self._policy(monkeypatch, "auto")
+        self._kind(monkeypatch, stream._VK_SDR10)
+        self._opencl(monkeypatch, True)
+        monkeypatch.setattr(stream, "_render_node_present", lambda: True)
+        assert stream._select_encode(
+            None, _FakeItem(codec_video="hevc"), transcode=True, src=self.SRC
+        ) == (False, False)
+
+    def test_auto_8bit_source_uses_plain_hw_not_tonemap(self, monkeypatch):
+        # An 8-bit SDR source takes the plain full-GPU scale path — never the tonemap graph — even where
+        # OpenCL is available.
+        self._policy(monkeypatch, "auto")
+        self._kind(monkeypatch, stream._VK_HWSAFE)
+        self._opencl(monkeypatch, True)
+        monkeypatch.setattr(stream, "_render_node_present", lambda: True)
+        assert stream._select_encode(
+            None, _FakeItem(codec_video="hevc"), transcode=True, src=self.SRC
+        ) == (True, False)
+
+    def test_off_forces_software_even_for_a_decodable_source(self, monkeypatch):
+        self._policy(monkeypatch, "off")
+        monkeypatch.setattr(stream, "_render_node_present", lambda: True)
+        assert (
+            stream._want_hw(None, _FakeItem(codec_video="hevc"), transcode=True, src=self.SRC)
+            is False
+        )
+
+    def test_on_forces_hw_and_skips_both_source_gates(self, monkeypatch):
+        # The admin override trusts the GPU; skips the decodability AND the bit-depth gate (the runtime
+        # HW→SW fallback still backstops it). Render node still required — HW is impossible without it.
+        self._policy(monkeypatch, "on")
+        self._hwsafe(monkeypatch, False)  # would veto in auto; "on" ignores it
+        self._opencl(
+            monkeypatch, False
+        )  # pin: tonemap-half is irrelevant here, keep it deterministic
+        monkeypatch.setattr(stream, "_render_node_present", lambda: True)
+        assert (
+            stream._want_hw(None, _FakeItem(codec_video="av1"), transcode=True, src=self.SRC)
+            is True
+        )
+        monkeypatch.setattr(stream, "_render_node_present", lambda: False)
+        assert (
+            stream._want_hw(None, _FakeItem(codec_video="hevc"), transcode=True, src=self.SRC)
+            is False
+        )
+
+    def test_on_still_picks_the_tonemap_graph_for_an_hdr_source(self, monkeypatch):
+        # "on" trusts the GPU but must still route a true-HDR source through the tonemap graph (plain
+        # scale_vaapi would hit the VPP wall) when OpenCL is present.
+        self._policy(monkeypatch, "on")
+        self._kind(monkeypatch, stream._VK_HDR)
+        self._opencl(monkeypatch, True)
+        monkeypatch.setattr(stream, "_render_node_present", lambda: True)
+        assert stream._select_encode(
+            None, _FakeItem(codec_video="hevc"), transcode=True, src=self.SRC
+        ) == (True, True)
+
+    def test_on_10bit_SDR_uses_plain_hw_not_tonemap(self, monkeypatch):
+        # F1 regression under "on": a 10-bit SDR source is NOT HDR, so even with OpenCL present "on" must
+        # pick plain HW (True, False) — the HDR tone curve must never touch an SDR picture.
+        self._policy(monkeypatch, "on")
+        self._kind(monkeypatch, stream._VK_SDR10)
+        self._opencl(monkeypatch, True)
+        monkeypatch.setattr(stream, "_render_node_present", lambda: True)
+        assert stream._select_encode(
+            None, _FakeItem(codec_video="hevc"), transcode=True, src=self.SRC
+        ) == (True, False)
+
+    def test_on_without_opencl_is_plain_hw(self, monkeypatch):
+        # "on" with no OpenCL runtime → plain HW, tonemap=False, regardless of source class (the runtime
+        # HW→SW fallback backstops a source the plain path can't actually handle). Pins the tonemap half
+        # of the "on" tuple, which test_on_forces_hw_and_skips_both_source_gates only checks via _want_hw.
+        self._policy(monkeypatch, "on")
+        self._kind(monkeypatch, stream._VK_HDR)  # even HDR: no runtime → can't tonemap on the GPU
+        self._opencl(monkeypatch, False)
+        monkeypatch.setattr(stream, "_render_node_present", lambda: True)
+        assert stream._select_encode(
+            None, _FakeItem(codec_video="hevc"), transcode=True, src=self.SRC
+        ) == (True, False)
+
+
+class TestColdStartWarmup:
+    """The cold-start buffer warm-up: before reporting a session ready, start_session waits for the
+    first _WARMUP_SEGMENTS video segments so hls.js doesn't drain a one-segment buffer and stall a
+    few seconds in (the auto-advance-to-next-episode stall). We spy on wait_for instead of running
+    ffmpeg."""
+
+    @pytest.fixture
+    def fake_env(self, tmp_path, monkeypatch):
+        monkeypatch.setattr(stream, "_HLS_ROOT", tmp_path)
+        monkeypatch.setattr(stream, "_sessions", {})
+        src = tmp_path / "movie.mkv"
+        src.write_bytes(b"x")
+        monkeypatch.setattr(stream.paths, "local_media_path", lambda db, fp: src)
+        monkeypatch.setattr(stream.sysconfig, "get_int", lambda db, k: 2)
+        monkeypatch.setattr(stream.subprocess, "Popen", lambda *a, **k: _FakeProc())
+        return tmp_path
+
+    def test_warmup_waits_for_the_first_few_segments(self, fake_env, monkeypatch):
+        waited = []
+
+        def spy(path, timeout=20.0, proc=None):
+            waited.append(path.name)
+            return True
+
+        monkeypatch.setattr(stream, "wait_for", spy)
+        s = stream.start_session(db=None, item=_FakeItem(), start_s=0.0)
+        assert s is not None
+        # seg_0 (unconditional now) + the warm-up run up to _WARMUP_SEGMENTS.
+        assert waited == [f"seg_{i}.ts" for i in range(stream._WARMUP_SEGMENTS)]
+
+    def test_warmup_stops_at_the_first_segment_that_isnt_ready(self, fake_env, monkeypatch):
+        waited = []
+
+        def spy(path, timeout=20.0, proc=None):
+            waited.append(path.name)
+            return path.name != "seg_1.ts"  # seg_1 never appears → warm-up gives up there
+
+        monkeypatch.setattr(stream, "wait_for", spy)
+        s = stream.start_session(db=None, item=_FakeItem(), start_s=0.0)
+        assert s is not None
+        assert waited == ["seg_0.ts", "seg_1.ts"]  # never asked for seg_2
+
+    def test_no_warmup_wait_when_the_first_segment_never_arrives(self, fake_env, monkeypatch):
+        # If seg_0 itself times out we don't warm up at all (nothing to build on) — and the session is
+        # still returned so the client's own segment requests can drive it, as before.
+        waited = []
+
+        def spy(path, timeout=20.0, proc=None):
+            waited.append(path.name)
+            return False
+
+        monkeypatch.setattr(stream, "wait_for", spy)
+        s = stream.start_session(db=None, item=_FakeItem(), start_s=0.0)
+        assert s is not None
+        assert waited == ["seg_0.ts"]
+
+
+class TestTranscodeStartSession:
+    """The seam TestTranscodeCommand can't reach: start_session reading the three admin knobs
+    (plex_transcode_preset/crf/max_height) and threading them + transcode/hw into the ffmpeg argv and
+    the HlsSession. A swapped knob here is a SILENT mis-encode (still plays), so pin the whole wiring
+    end-to-end with a real (captured) Popen argv — not just _ffmpeg_cmd called with literals."""
+
+    @pytest.fixture
+    def capturing_env(self, tmp_path, monkeypatch):
+        monkeypatch.setattr(stream, "_HLS_ROOT", tmp_path)
+        monkeypatch.setattr(stream, "_sessions", {})
+        src = tmp_path / "movie.mkv"
+        src.write_bytes(b"x")
+        monkeypatch.setattr(stream.paths, "local_media_path", lambda db, fp: src)
+        # Distinct sentinels per knob so a crf<->max_height swap (both ints, both via get_int) fails.
+        monkeypatch.setattr(
+            stream.sysconfig,
+            "get_int",
+            lambda db, k: {
+                "plex_transcode_crf": 18,
+                "plex_transcode_max_height": 480,
+                "plex_max_transcodes": 4,
+            }[k],
+        )
+        monkeypatch.setattr(
+            stream.sysconfig,
+            "get_str",
+            lambda db, k: {"plex_transcode_preset": "slow"}.get(k, "auto"),
+        )
+        monkeypatch.setattr(stream, "wait_for", lambda path, timeout=20.0, proc=None: True)
+        _CapturingProc.calls = []
+        monkeypatch.setattr(stream.subprocess, "Popen", _CapturingProc)
+        return tmp_path
+
+    def test_software_transcode_threads_the_knobs_into_the_command(
+        self, capturing_env, monkeypatch
+    ):
+        monkeypatch.setattr(
+            stream, "_select_encode", lambda db, item, transcode, src: (False, False)
+        )
+        s = stream.start_session(
+            db=None, item=_FakeItem(codec_video="mpeg4"), start_s=0.0, transcode=True
+        )
+        assert s is not None and s.transcode is True and s.hw is False
+        (cmd, *_), kwargs = _CapturingProc.calls[0]
+        assert _venc(cmd) == "libx264"
+        assert cmd[cmd.index("-preset") + 1] == "slow"  # plex_transcode_preset
+        assert cmd[cmd.index("-crf") + 1] == "18"  # plex_transcode_crf, NOT max_height
+        assert cmd[cmd.index("-vf") + 1] == "scale=-2:min(ih\\,480)"  # plex_transcode_max_height
+        # The CPU-bound child is niced via preexec_fn on POSIX (the API process itself must not be).
+        if os.name == "posix":
+            assert kwargs.get("preexec_fn") is stream._sw_child_preexec
+
+    def test_hardware_transcode_uses_the_gpu_and_never_nices(self, capturing_env, monkeypatch):
+        monkeypatch.setattr(
+            stream, "_select_encode", lambda db, item, transcode, src: (True, False)
+        )
+        s = stream.start_session(
+            db=None, item=_FakeItem(codec_video="hevc"), start_s=0.0, transcode=True
+        )
+        assert s is not None and s.transcode is True and s.hw is True and s.tonemap is False
+        assert len(_CapturingProc.calls) == 1  # first segment arrived — no HW→SW fallback respawn
+        (cmd, *_), kwargs = _CapturingProc.calls[0]
+        assert _venc(cmd) == "h264_vaapi"
+        assert "libx264" not in cmd
+        # Plain-HW path unconditionally emits the nv12 downconvert (a disjunction on "-vf not in cmd"
+        # would silently pass if the filter were dropped — assert it is actually present).
+        assert cmd[cmd.index("-vf") + 1] == "scale_vaapi=format=nv12"  # no SW cap
+        assert kwargs.get("preexec_fn") is None  # GPU encode is cheap — never niced
+
+    def test_hdr_tonemap_transcode_threads_the_opencl_graph_and_flags_the_session(
+        self, capturing_env, monkeypatch
+    ):
+        # A HW tonemap session (10-bit/HDR + OpenCL) must build the OpenCL graph in the argv and carry
+        # tonemap=True on the session, still on the GPU (hw=True) and never niced.
+        monkeypatch.setattr(stream, "_select_encode", lambda db, item, transcode, src: (True, True))
+        s = stream.start_session(
+            db=None, item=_FakeItem(codec_video="hevc"), start_s=0.0, transcode=True
+        )
+        assert s is not None and s.transcode is True and s.hw is True and s.tonemap is True
+        (cmd, *_), kwargs = _CapturingProc.calls[0]
+        assert _venc(cmd) == "h264_vaapi"
+        assert "opencl=ocl@va" in cmd and cmd[cmd.index("-filter_hw_device") + 1] == "ocl"
+        assert "tonemap_opencl=" in cmd[cmd.index("-vf") + 1]
+        assert kwargs.get("preexec_fn") is None
+
+    def test_a_hw_session_that_produces_nothing_falls_back_to_software(
+        self, capturing_env, monkeypatch
+    ):
+        # BUG 1 backstop: _want_hw picked HW but the VAAPI session emits no first segment (a VAProfile
+        # refusal the gates didn't catch). start_session must respawn on libx264 and report hw=False so
+        # the item still plays and the route/player honestly show CPU.
+        monkeypatch.setattr(
+            stream, "_select_encode", lambda db, item, transcode, src: (True, False)
+        )
+        seen = {"n": 0}
+
+        def flaky_wait(path, timeout=20.0, proc=None):
+            seen["n"] += 1
+            return seen["n"] > 1  # the first seg-0 wait (HW) fails; every wait after succeeds (SW)
+
+        monkeypatch.setattr(stream, "wait_for", flaky_wait)
+        s = stream.start_session(
+            db=None, item=_FakeItem(codec_video="hevc"), start_s=0.0, transcode=True
+        )
+        assert (
+            s is not None and s.transcode is True and s.hw is False
+        )  # honest CPU after the fallback
+        assert len(_CapturingProc.calls) == 2  # the HW attempt, then the SW respawn
+        (hw_cmd, *_), _ = _CapturingProc.calls[0]
+        (sw_cmd, *_), sw_kwargs = _CapturingProc.calls[1]
+        assert _venc(hw_cmd) == "h264_vaapi"
+        assert _venc(sw_cmd) == "libx264"
+        if os.name == "posix":
+            assert sw_kwargs.get("preexec_fn") is stream._sw_child_preexec  # the SW child is niced
+
+    def test_a_hw_TONEMAP_session_that_produces_nothing_falls_back_to_software(
+        self, capturing_env, monkeypatch
+    ):
+        # The fallback gate is `not ready and s.hw`, shared by plain-HW and tonemap sessions — but only
+        # the plain-HW variant was covered. Pin the tonemap variant too: a (True, True) session that
+        # emits nothing (an OpenCL/tonemap init refusal) must respawn on libx264 and end hw=False,
+        # tonemap=False, so an HDR item still plays on CPU.
+        monkeypatch.setattr(stream, "_select_encode", lambda db, item, transcode, src: (True, True))
+        seen = {"n": 0}
+
+        def flaky_wait(path, timeout=20.0, proc=None):
+            seen["n"] += 1
+            return (
+                seen["n"] > 1
+            )  # the first seg-0 wait (HW tonemap) fails; every wait after succeeds
+
+        monkeypatch.setattr(stream, "wait_for", flaky_wait)
+        s = stream.start_session(
+            db=None, item=_FakeItem(codec_video="hevc"), start_s=0.0, transcode=True
+        )
+        assert s is not None and s.transcode is True and s.hw is False and s.tonemap is False
+        assert len(_CapturingProc.calls) == 2  # the HW tonemap attempt, then the SW respawn
+        (hw_cmd, *_), _ = _CapturingProc.calls[0]
+        (sw_cmd, *_), _ = _CapturingProc.calls[1]
+        assert (
+            "tonemap_opencl=" in hw_cmd[hw_cmd.index("-vf") + 1]
+        )  # first attempt built the OpenCL graph
+        assert _venc(sw_cmd) == "libx264"  # respawn is plain software, no tonemap
+
+    def test_a_superseded_hw_session_does_not_respawn_over_the_newer_one(
+        self, capturing_env, monkeypatch
+    ):
+        # F2/race: start_session waits on seg_0 OUTSIDE _lock. If a concurrent same-key start (a rapid
+        # seek-restart) or _enforce_cap replaces _sessions[key] while we wait, our proc dying must NOT
+        # trigger the SW fallback — that would tear down the NEWER session and breach the transcode cap.
+        # The identity guard must detect it's been superseded and yield the currently-registered session.
+        monkeypatch.setattr(
+            stream, "_select_encode", lambda db, item, transcode, src: (True, False)
+        )
+
+        class _Newer:  # stands in for the session a concurrent _spawn registered
+            hw = True
+            tonemap = False
+            transcode = True
+            last_access = 0.0
+
+        newer = _Newer()
+
+        def wait_then_supersede(path, timeout=20.0, proc=None):
+            # Simulate the concurrent replacement happening during our out-of-lock wait, then report the
+            # (now-killed) HW proc produced nothing.
+            stream._sessions["12345"] = newer
+            return False
+
+        monkeypatch.setattr(stream, "wait_for", wait_then_supersede)
+        s = stream.start_session(
+            db=None, item=_FakeItem(codec_video="hevc"), start_s=0.0, transcode=True
+        )
+        # No SW respawn — only the initial HW _spawn ran; the newer session was left intact.
+        assert len(_CapturingProc.calls) == 1
+        assert s is newer  # yielded the currently-registered session, did not clobber it
+        assert stream._sessions["12345"] is newer
+
+    def test_a_cap_culled_hw_session_does_not_respawn_and_is_not_reported_missing(
+        self, capturing_env, monkeypatch
+    ):
+        # F2/race, the cull sub-case: while we wait on seg_0 out of lock, cross-key cap pressure lets
+        # _enforce_cap evict THIS session's key entirely (no replacement). The fallback must still not
+        # respawn (that would re-breach the cap the cull just enforced), and must NOT return None — a None
+        # is turned by the route into a dishonest "file not found" 404 for a file that exists. It yields
+        # our own (now-dead) session instead, so the client's segment requests degrade to the retryable
+        # "not available yet" path.
+        monkeypatch.setattr(
+            stream, "_select_encode", lambda db, item, transcode, src: (True, False)
+        )
+        captured = {}
+
+        def wait_then_cull(path, timeout=20.0, proc=None):
+            captured["s"] = stream._sessions[
+                "12345"
+            ]  # the HW session the initial _spawn just registered
+            del stream._sessions[
+                "12345"
+            ]  # simulate _enforce_cap dropping the LRU under cap pressure
+            return False
+
+        monkeypatch.setattr(stream, "wait_for", wait_then_cull)
+        s = stream.start_session(
+            db=None, item=_FakeItem(codec_video="hevc"), start_s=0.0, transcode=True
+        )
+        assert (
+            len(_CapturingProc.calls) == 1
+        )  # no SW respawn — the cull is respected, cap not re-breached
+        assert (
+            s is captured["s"]
+        )  # our own session yielded, NOT None (which the route would 404 as missing)
+        assert "12345" not in stream._sessions  # the culled key stays gone
+
+    def test_remux_reads_no_transcode_knobs_and_stream_copies(self, capturing_env, monkeypatch):
+        # A remux start must stream-copy the video and spawn no niced child (the transcode knobs and
+        # the preexec nice are gated behind `transcode=True`).
+        monkeypatch.setattr(
+            stream, "_select_encode", lambda db, item, transcode, src: (False, False)
+        )
+        s = stream.start_session(db=None, item=_FakeItem(), start_s=0.0)  # transcode defaults False
+        assert s is not None and s.transcode is False
+        (cmd, *_), kwargs = _CapturingProc.calls[0]
+        assert _venc(cmd) == "copy"
+        assert kwargs.get("preexec_fn") is None
+
+
+class TestProbeVideoKind:
+    """The ffprobe-based source classifier that routes the transcode pipeline: 8-bit SDR → plain VAAPI;
+    true-HDR (PQ/HLG) → the OpenCL tonemap graph; 10-bit *SDR* → software (an exact downconvert, NEVER
+    the HDR tone curve — the F1 distinction). Exercises the REAL function body (not a monkeypatch)."""
+
+    @staticmethod
+    def _probe(monkeypatch, stdout):
+        class _R:
+            def __init__(self):
+                self.stdout = stdout
+
+        monkeypatch.setattr(stream.subprocess, "run", lambda *a, **k: _R())
+
+    def test_8bit_sdr_is_hwsafe(self, monkeypatch):
+        self._probe(monkeypatch, "pix_fmt=yuv420p\nbits_per_raw_sample=8\ncolor_transfer=bt709\n")
+        assert stream._probe_video_kind(Path("/x")) == stream._VK_HWSAFE
+
+    def test_10bit_sdr_pix_fmt_is_sdr10(self, monkeypatch):
+        # yuv420p10le with a non-HDR transfer (bt2020-10 is NOT PQ/HLG) = 10-bit SDR → software, not
+        # tonemap. Signalled by the pix_fmt suffix even when bits_per_raw_sample is absent.
+        self._probe(monkeypatch, "pix_fmt=yuv420p10le\ncolor_transfer=bt2020-10\n")
+        assert stream._probe_video_kind(Path("/x")) == stream._VK_SDR10
+
+    def test_bits_per_raw_sample_over_8_sdr_is_sdr10(self, monkeypatch):
+        self._probe(monkeypatch, "pix_fmt=yuv420p\nbits_per_raw_sample=10\ncolor_transfer=bt709\n")
+        assert stream._probe_video_kind(Path("/x")) == stream._VK_SDR10
+
+    def test_pq_transfer_is_hdr(self, monkeypatch):
+        # PQ (smpte2084) is true HDR — needs a real tonemap, even if only 8-bit-tagged.
+        self._probe(
+            monkeypatch, "pix_fmt=yuv420p10le\nbits_per_raw_sample=10\ncolor_transfer=smpte2084\n"
+        )
+        assert stream._probe_video_kind(Path("/x")) == stream._VK_HDR
+
+    def test_hlg_transfer_is_hdr(self, monkeypatch):
+        # HLG (arib-std-b67) is the other HDR transfer — previously untested; it must classify as HDR.
+        self._probe(
+            monkeypatch,
+            "pix_fmt=yuv420p10le\nbits_per_raw_sample=10\ncolor_transfer=arib-std-b67\n",
+        )
+        assert stream._probe_video_kind(Path("/x")) == stream._VK_HDR
+
+    def test_empty_probe_output_is_hwsafe(self, monkeypatch):
+        # A probe that returns nothing (no streams / stripped metadata) → assume hwsafe; the runtime
+        # HW→SW fallback backstops a wrong guess.
+        self._probe(monkeypatch, "")
+        assert stream._probe_video_kind(Path("/x")) == stream._VK_HWSAFE
+
+    def test_probe_failure_assumes_hwsafe(self, monkeypatch):
+        # ffprobe missing/erroring → assume hwsafe; the runtime HW→SW fallback is the real backstop, so a
+        # probe miss costs at most one wasted HW attempt, never a stranded item.
+        def boom(*a, **k):
+            raise OSError("no ffprobe")
+
+        monkeypatch.setattr(stream.subprocess, "run", boom)
+        assert stream._probe_video_kind(Path("/x")) == stream._VK_HWSAFE
+
+
+class TestOpenclPresent:
+    """The OpenCL-runtime probe (_opencl_present) — the precondition for the HW HDR tonemap graph. Drives
+    the REAL glob against a temp ICD dir instead of monkeypatching the function, so a regression to the
+    ICD path / glob / OSError guard would be caught (this routes every HDR source on prod)."""
+
+    def test_true_when_an_icd_file_is_registered(self, tmp_path, monkeypatch):
+        monkeypatch.setattr(stream, "_OPENCL_ICD_DIR", tmp_path)
+        (tmp_path / "intel.icd").write_text("libintelocl.so\n")
+        assert stream._opencl_present() is True
+
+    def test_false_when_the_dir_is_empty(self, tmp_path, monkeypatch):
+        monkeypatch.setattr(stream, "_OPENCL_ICD_DIR", tmp_path)
+        assert stream._opencl_present() is False
+
+    def test_false_and_no_raise_when_the_dir_is_missing(self, tmp_path, monkeypatch):
+        # A missing dir: Path.glob yields nothing (no raise) → False.
+        monkeypatch.setattr(stream, "_OPENCL_ICD_DIR", tmp_path / "nope")
+        assert stream._opencl_present() is False
+
+    def test_false_when_glob_raises_oserror(self, monkeypatch):
+        # The `except OSError` guard proper: an unreadable ICD dir (permission denied) makes glob RAISE,
+        # not return empty. That must be swallowed to False, never propagated up through _select_encode
+        # into start_session (which would crash HDR routing).
+        class _BoomDir:
+            def glob(self, pattern):
+                raise OSError("permission denied")
+
+        monkeypatch.setattr(stream, "_OPENCL_ICD_DIR", _BoomDir())
+        assert stream._opencl_present() is False
+
+
+class TestWaitForProcFastFail:
+    """wait_for(proc=…) must stop as soon as the ffmpeg proc exits (a VAAPI init refusal dies in ~1s
+    producing nothing) instead of blocking the whole timeout — that fast-fail is what keeps the HW→SW
+    fallback from turning into a 25s stall. Exercises the REAL wait_for (every other test monkeypatches
+    it wholesale, so this branch would otherwise never run)."""
+
+    class _DeadProc:
+        def poll(self):
+            return 1  # already exited non-zero
+
+    def test_returns_true_when_the_segment_exists_despite_a_dead_proc(self, tmp_path):
+        seg = tmp_path / "seg_0.ts"
+        seg.write_bytes(b"x")
+        # The proc exited but DID write a first segment → ready. (The final existence re-check.)
+        assert stream.wait_for(seg, timeout=5.0, proc=self._DeadProc()) is True
+
+    def test_returns_false_fast_when_a_dead_proc_wrote_nothing(self, tmp_path):
+        # Missing segment + dead proc → give up immediately, not after `timeout`. Assert it's fast by
+        # using a long timeout the test would visibly hang on if the fast-fail branch regressed.
+        seg = tmp_path / "seg_0.ts"
+        assert stream.wait_for(seg, timeout=30.0, proc=self._DeadProc()) is False
+
+    def test_empty_segment_from_a_dead_proc_is_not_ready(self, tmp_path):
+        # A zero-byte segment is not a real segment (size > 0 required).
+        seg = tmp_path / "seg_0.ts"
+        seg.write_bytes(b"")
+        assert stream.wait_for(seg, timeout=30.0, proc=self._DeadProc()) is False

backend/tests/test_plex_watch_sync.py

@@ -0,0 +1,386 @@
+"""S2 watch-sync semantics: Plex is the source of truth.
+
+Two independent pieces:
+- `_pull_apply` (DB lane): on a genuine divergence for an item Plex knows about, Plex now WINS —
+  the old "keep Siftlode when it's newer within a tolerance" tug-of-war is gone. The anti-bounce
+  short-circuit (`_same_state` + `synced_to_plex`) must still keep a freshly-pushed row from bouncing.
+- `_should_push_resume` (pure): the in-memory write-back throttle — a `final` checkpoint always pushes,
+  a periodic one pushes at most once per _PUSH_THROTTLE_S seconds per (user, item).
+"""
+
+from datetime import datetime, timedelta, timezone
+from types import SimpleNamespace
+
+from sqlalchemy import select
+
+from app.models import PlexItem, PlexLibrary, PlexState, User
+from app.plex.watch_sync import _pull_apply, _reconcile_inprogress_movies
+from app.routes.plex.playback import (
+    _PUSH_THROTTLE_S,
+    _resume_push_superseded,
+    _should_push_resume,
+)
+
+
+def _seed_item_and_user(db):
+    lib = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+    db.add(lib)
+    db.flush()
+    item = PlexItem(rating_key="m1", library_id=lib.id, kind="movie", title="A Movie")
+    db.add(item)
+    user = User(email="watch@example.com")
+    db.add(user)
+    db.flush()
+    return item.id, user.id
+
+
+class _FakePlex:
+    """Minimal PlexClient stand-in for the movie-probe tests: metadata(rating_key) → a leaf dict."""
+
+    def __init__(self, by_rk: dict[str, dict]):
+        self._by_rk = by_rk
+
+    def metadata(self, rating_key: str, markers: bool = False):
+        return self._by_rk.get(str(rating_key))
+
+
+def test_pull_plex_wins_over_diverging_synced_local_resume(db):
+    """The core S2 change: a SYNCED local row (its state already reached Plex) that later diverges from
+    Plex = a real external Plex-side change, so the incremental pull resolves to PLEX's position — Plex
+    is authoritative, no LWW. (A DIRTY local row is protected instead — see the dirty-guard test.)"""
+    item_id, user_id = _seed_item_and_user(db)
+    now = datetime.now(timezone.utc)
+    db.add(
+        PlexState(
+            user_id=user_id,
+            item_id=item_id,
+            status="new",
+            position_seconds=300,
+            progress_updated_at=now,  # local touched just now — "newer" than Plex
+            synced_to_plex=True,  # but already pushed → a later Plex divergence is an external change
+        )
+    )
+    db.flush()
+
+    # Plex reports a DIFFERENT (older) resume position for the same item.
+    changed = _pull_apply(db, user_id, item_id, "new", 120, plex_ts=now - timedelta(seconds=60))
+    db.flush()
+
+    assert changed == "in_progress"
+    st = (
+        db.execute(
+            select(PlexState).where(PlexState.user_id == user_id, PlexState.item_id == item_id)
+        )
+        .scalars()
+        .one()
+    )
+    assert st.position_seconds == 120, "Plex's position must win, even though local was newer"
+    assert st.synced_to_plex is True
+
+
+def test_pull_plex_watched_wins_over_synced_local_in_progress(db):
+    """Plex marking the item watched propagates over a SYNCED local in-progress row (external change)."""
+    item_id, user_id = _seed_item_and_user(db)
+    now = datetime.now(timezone.utc)
+    db.add(
+        PlexState(
+            user_id=user_id,
+            item_id=item_id,
+            status="new",
+            position_seconds=300,
+            progress_updated_at=now,
+            synced_to_plex=True,
+        )
+    )
+    db.flush()
+
+    changed = _pull_apply(db, user_id, item_id, "watched", 0, plex_ts=now - timedelta(seconds=60))
+    db.flush()
+
+    assert changed == "watched"
+    st = (
+        db.execute(
+            select(PlexState).where(PlexState.user_id == user_id, PlexState.item_id == item_id)
+        )
+        .scalars()
+        .one()
+    )
+    assert st.status == "watched"
+    assert st.position_seconds == 0
+
+
+def test_pull_no_bounce_on_matching_row(db):
+    """Anti-bounce short-circuit: when the row already matches what Plex reports (a just-pushed
+    resume), the pull makes NO change and only settles the synced flag — no churn, no re-pull."""
+    item_id, user_id = _seed_item_and_user(db)
+    now = datetime.now(timezone.utc)
+    db.add(
+        PlexState(
+            user_id=user_id,
+            item_id=item_id,
+            status="new",
+            position_seconds=100,
+            progress_updated_at=now,
+            synced_to_plex=True,  # freshly pushed
+        )
+    )
+    db.flush()
+
+    # Plex echoes the same position a beat later (well within the _PROGRESS_MIN_S fuzz).
+    changed = _pull_apply(db, user_id, item_id, "new", 102, plex_ts=now + timedelta(seconds=2))
+    db.flush()
+
+    assert changed is None, "a matching row must not bounce"
+    st = (
+        db.execute(
+            select(PlexState).where(PlexState.user_id == user_id, PlexState.item_id == item_id)
+        )
+        .scalars()
+        .one()
+    )
+    assert st.position_seconds == 100, "no churn to the stored position"
+
+
+def test_pull_keeps_dirty_local_on_divergence(db):
+    """Durability guard: a DIRTY row (a local change whose immediate push failed → synced_to_plex=False)
+    must NOT be overwritten by a diverging Plex signal, and must stay dirty so `_repush_dirty` can push
+    the local value up. Overwriting-and-clearing here would strand the local change forever."""
+    item_id, user_id = _seed_item_and_user(db)
+    now = datetime.now(timezone.utc)
+    db.add(
+        PlexState(
+            user_id=user_id,
+            item_id=item_id,
+            status="watched",  # user just marked watched locally; the scrobble to Plex failed
+            position_seconds=0,
+            watched_at=now,
+            progress_updated_at=now,
+            synced_to_plex=False,  # dirty — never reached Plex
+        )
+    )
+    db.flush()
+
+    # Plex still lists it in on_deck at an old in-progress offset (it never got the watched scrobble).
+    changed = _pull_apply(db, user_id, item_id, "new", 240, plex_ts=now - timedelta(seconds=60))
+    db.flush()
+
+    assert changed is None, "a dirty local row must not be clobbered by the pull"
+    st = (
+        db.execute(
+            select(PlexState).where(PlexState.user_id == user_id, PlexState.item_id == item_id)
+        )
+        .scalars()
+        .one()
+    )
+    assert st.status == "watched", "local watched preserved"
+    assert st.position_seconds == 0
+    assert st.synced_to_plex is False, "stays dirty so _repush_dirty retries the push"
+
+
+def test_pull_settles_flag_on_matching_dirty_row(db):
+    """Anti-bounce, dirty branch: a row that already MATCHES Plex but is still dirty gets its
+    synced_to_plex flag settled to True (no churn), so `_repush_dirty` stops re-pushing it forever."""
+    item_id, user_id = _seed_item_and_user(db)
+    now = datetime.now(timezone.utc)
+    db.add(
+        PlexState(
+            user_id=user_id,
+            item_id=item_id,
+            status="new",
+            position_seconds=100,
+            progress_updated_at=now,
+            synced_to_plex=False,  # dirty, but already agrees with Plex
+        )
+    )
+    db.flush()
+
+    changed = _pull_apply(db, user_id, item_id, "new", 102, plex_ts=now + timedelta(seconds=2))
+    db.flush()
+
+    assert changed is None, "a matching row makes no change"
+    st = (
+        db.execute(
+            select(PlexState).where(PlexState.user_id == user_id, PlexState.item_id == item_id)
+        )
+        .scalars()
+        .one()
+    )
+    assert st.position_seconds == 100, "no churn to the stored position"
+    assert st.synced_to_plex is True, "the dirty flag is settled so it isn't re-pushed endlessly"
+
+
+def test_movie_probe_flips_stale_in_progress_to_watched(db):
+    """S1 core: a local in-progress MOVIE that Plex has since finished (viewCount>0) and dropped from
+    Continue-Watching flips to watched on the incremental pass — without waiting for the daily reconcile.
+    This is the "movie stuck in progress after scrubbing the credits" bug."""
+    item_id, user_id = _seed_item_and_user(db)
+    now = datetime.now(timezone.utc)
+    db.add(
+        PlexState(
+            user_id=user_id,
+            item_id=item_id,
+            status="new",
+            position_seconds=300,
+            progress_updated_at=now,
+            synced_to_plex=True,  # was created by a prior pull; the user then watched it on Plex
+        )
+    )
+    db.flush()
+
+    # Plex now reports the movie watched (viewCount>0, no offset) and it is NOT on the deck.
+    plex = _FakePlex({"m1": {"viewCount": 1, "lastViewedAt": int(now.timestamp())}})
+    out = _reconcile_inprogress_movies(
+        db, plex, SimpleNamespace(user_id=user_id), on_deck_ids=set()
+    )
+    db.flush()
+
+    assert out == {"watched": 1, "in_progress": 0, "probed": 1}
+    st = (
+        db.execute(
+            select(PlexState).where(PlexState.user_id == user_id, PlexState.item_id == item_id)
+        )
+        .scalars()
+        .one()
+    )
+    assert st.status == "watched"
+    assert st.position_seconds == 0
+
+
+def test_movie_probe_skips_ondeck_and_episodes(db):
+    """The probe must NOT touch (a) a movie Plex still lists on the deck — it's legitimately in
+    progress — nor (b) an in-progress EPISODE (episodes ride onDeck/history + rollup). Only stale
+    in-progress movies are probed, and metadata() is called for those alone."""
+    lib = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+    db.add(lib)
+    db.flush()
+    on_deck_movie = PlexItem(rating_key="mDeck", library_id=lib.id, kind="movie", title="On deck")
+    episode = PlexItem(rating_key="e1", library_id=lib.id, kind="episode", title="An episode")
+    db.add_all([on_deck_movie, episode])
+    user = User(email="probe2@example.com")
+    db.add(user)
+    db.flush()
+    now = datetime.now(timezone.utc)
+    for iid in (on_deck_movie.id, episode.id):
+        db.add(
+            PlexState(
+                user_id=user.id,
+                item_id=iid,
+                status="new",
+                position_seconds=300,
+                progress_updated_at=now,
+                synced_to_plex=True,
+            )
+        )
+    db.flush()
+
+    # Plex would report both watched — but neither should be probed at all, so the fake returning
+    # "watched" must have NO effect.
+    plex = _FakePlex(
+        {
+            "mDeck": {"viewCount": 1, "lastViewedAt": int(now.timestamp())},
+            "e1": {"viewCount": 1, "lastViewedAt": int(now.timestamp())},
+        }
+    )
+    out = _reconcile_inprogress_movies(
+        db, plex, SimpleNamespace(user_id=user.id), on_deck_ids={on_deck_movie.id}
+    )
+    db.flush()
+
+    assert out == {"watched": 0, "in_progress": 0, "probed": 0}, "neither item is probed"
+    for iid in (on_deck_movie.id, episode.id):
+        st = (
+            db.execute(
+                select(PlexState).where(PlexState.user_id == user.id, PlexState.item_id == iid)
+            )
+            .scalars()
+            .one()
+        )
+        assert st.status == "new" and st.position_seconds == 300, "left untouched"
+
+
+def test_movie_probe_leaves_row_when_plex_has_no_signal(db):
+    """If Plex reports no watch signal (viewCount 0, no offset) for a probed movie, the incremental pass
+    must NOT clear the local in-progress row — un-watch is the daily reconcile's job, and a Siftlode-only
+    in-progress state must survive."""
+    item_id, user_id = _seed_item_and_user(db)
+    now = datetime.now(timezone.utc)
+    db.add(
+        PlexState(
+            user_id=user_id,
+            item_id=item_id,
+            status="new",
+            position_seconds=300,
+            progress_updated_at=now,
+            synced_to_plex=True,
+        )
+    )
+    db.flush()
+
+    plex = _FakePlex({"m1": {"viewCount": 0}})
+    out = _reconcile_inprogress_movies(
+        db, plex, SimpleNamespace(user_id=user_id), on_deck_ids=set()
+    )
+    db.flush()
+
+    assert out == {"watched": 0, "in_progress": 0, "probed": 1}
+    st = (
+        db.execute(
+            select(PlexState).where(PlexState.user_id == user_id, PlexState.item_id == item_id)
+        )
+        .scalars()
+        .one()
+    )
+    assert st.status == "new" and st.position_seconds == 300, "in-progress row preserved"
+
+
+def test_should_push_resume_scopes_by_user_and_item():
+    """The throttle window is keyed by the FULL (user, item) tuple: pushing for one key must not
+    suppress a distinct user or a distinct item within the same window."""
+    now = datetime.now(timezone.utc)
+    assert _should_push_resume(9101, 9201, now, final=False) is True  # (u1, i1) first tick
+    # Same window, different item for the same user → independent, still pushes.
+    assert _should_push_resume(9101, 9202, now, final=False) is True
+    # Same window, different user, same item → independent, still pushes.
+    assert _should_push_resume(9102, 9201, now, final=False) is True
+    # And the original key is still throttled within its window (proves the above weren't just "always").
+    assert _should_push_resume(9101, 9201, now + timedelta(seconds=1), final=False) is False
+
+
+def test_resume_push_superseded_drops_older_pending_push():
+    """The write-ordering guard: an older still-pending resume push is dropped once a newer push for the
+    same (user, item) has been scheduled, so a reordered stale position can't land at Plex last."""
+    key = (9301, 9301)
+    t0 = datetime.now(timezone.utc)
+    # Schedule an initial push at t0 (records t0 as the last-push time for this key).
+    assert _should_push_resume(*key, t0, final=False) is True
+    # Nothing newer yet → the t0 push is current, not superseded.
+    assert _resume_push_superseded(*key, t0) is False
+    # A newer push (e.g. a backward seek) is scheduled at t1 > t0.
+    t1 = t0 + timedelta(seconds=1)
+    assert _should_push_resume(*key, t1, final=True) is True
+    # Now the still-pending t0 push is superseded and must drop; the t1 push is current.
+    assert _resume_push_superseded(*key, t0) is True
+    assert _resume_push_superseded(*key, t1) is False
+
+
+def test_should_push_resume_final_always_pushes():
+    """A final checkpoint (pause / seek / stop) always pushes, bypassing the throttle."""
+    now = datetime.now(timezone.utc)
+    key = (9001, 9001)
+    assert _should_push_resume(*key, now, final=True) is True
+    # A second final a fraction of a second later still pushes.
+    assert _should_push_resume(*key, now + timedelta(seconds=1), final=True) is True
+
+
+def test_should_push_resume_periodic_is_throttled():
+    """Periodic (non-final) checkpoints push at most once per _PUSH_THROTTLE_S per (user, item)."""
+    now = datetime.now(timezone.utc)
+    key = (9002, 9002)
+    assert _should_push_resume(*key, now, final=False) is True  # first tick pushes
+    # A tick within the window is suppressed.
+    assert (
+        _should_push_resume(*key, now + timedelta(seconds=_PUSH_THROTTLE_S - 1), final=False)
+        is False
+    )
+    # Once the window elapses, the next tick pushes again.
+    assert _should_push_resume(*key, now + timedelta(seconds=_PUSH_THROTTLE_S), final=False) is True

backend/tests/test_ratelimit.py

@@ -0,0 +1,65 @@
+"""The sliding-window limiter behind /auth/register, password-login, password-reset and demo.
+
+Pure logic, no DB. `reset()` in particular is only ever called by a test fixture (conftest clears
+the module-level limiters between tests), so without a test here a refactor could turn it into a
+no-op and nothing would notice until an unrelated test started failing with a 429.
+"""
+
+from app import ratelimit
+from app.ratelimit import RateLimiter
+
+
+def test_allow_trips_at_the_cap_and_stays_tripped():
+    lim = RateLimiter(max_events=2, window_seconds=300)
+
+    assert lim.allow("ip") is True
+    assert lim.allow("ip") is True
+    assert lim.allow("ip") is False
+    assert lim.allow("ip") is False
+
+
+def test_hammering_while_blocked_does_not_push_the_window_forward(monkeypatch):
+    # A blocked attempt must not be recorded, otherwise someone who keeps retrying holds their own
+    # window open forever — an indefinite lockout for anyone sharing that IP. Only observable across
+    # the window boundary, so drive the clock: two attempts fill the cap, ten blocked retries land
+    # just before it expires, and the caller must still be let back in on the far side.
+    clock = {"t": 1000.0}
+    monkeypatch.setattr(ratelimit.time, "monotonic", lambda: clock["t"])
+    lim = RateLimiter(max_events=2, window_seconds=60)
+
+    assert lim.allow("ip") is True
+    assert lim.allow("ip") is True
+    for _ in range(10):
+        clock["t"] += 5  # still inside the window; every one of these is refused
+        assert lim.allow("ip") is False
+
+    clock["t"] = 1000.0 + 61  # past the window of the two attempts that actually counted
+    assert lim.allow("ip") is True
+
+
+def test_keys_are_independent():
+    lim = RateLimiter(max_events=1, window_seconds=300)
+
+    assert lim.allow("a") is True
+    assert lim.allow("a") is False
+    assert lim.allow("b") is True
+
+
+def test_reset_clears_every_key():
+    lim = RateLimiter(max_events=1, window_seconds=300)
+    lim.allow("a")
+    lim.allow("b")
+    assert lim.allow("a") is False
+
+    lim.reset()
+
+    assert lim.allow("a") is True
+    assert lim.allow("b") is True
+
+
+def test_expired_attempts_fall_out_of_the_window():
+    # A zero-length window means every previous attempt is already outside it.
+    lim = RateLimiter(max_events=1, window_seconds=0)
+
+    assert lim.allow("ip") is True
+    assert lim.allow("ip") is True

backend/tests/test_reset_link_states.py

@@ -0,0 +1,90 @@
+"""What a dead email link says, and what it costs to ask (E9.5 S4 follow-up), DB-lane.
+
+Reported 2026-09-05: delete an account, then open its password-reset link. The card drew a full
+"set a new password" form — because a `#reset=` fragment was present, nothing more — and only after
+the user typed a password did the server answer 400. No security hole (the account's tokens cascade
+away with it, so nothing can be set on a deleted or a re-created account), but a dead end of exactly
+the kind this epic exists to remove.
+
+The fix is a check that does NOT spend the token, so the pre-flight can never cost the user their
+one real attempt. That is the property most worth pinning here.
+"""
+
+from app.routes.auth import RESET_TTL, _issue_token
+
+_PW = "correct horse battery"
+_NEW = "brand new password"
+
+
+def _issue(db, user):
+    raw = _issue_token(db, user, "reset", RESET_TTL)
+    db.commit()
+    return raw
+
+
+def test_checking_a_live_link_does_not_spend_it(client, db, make_user):
+    raw = _issue(db, make_user(email="live@example.com", password=_PW))
+
+    assert client.post("/auth/password-reset/check", json={"token": raw}).json() == {"ok": True}
+    assert client.post("/auth/password-reset/check", json={"token": raw}).json() == {"ok": True}
+
+    # The whole point: after any number of checks the one real attempt is still there.
+    assert client.post(
+        "/auth/password-reset/confirm", json={"token": raw, "password": _NEW}
+    ).json() == {"ok": True}
+
+
+def test_a_link_whose_account_was_deleted_is_reported_dead(client, db, make_user):
+    user = make_user(email="gone@example.com", password=_PW)
+    raw = _issue(db, user)
+    db.delete(user)
+    db.commit()
+
+    assert client.post("/auth/password-reset/check", json={"token": raw}).json() == {"ok": False}
+
+    # And the confirm agrees, in the structured shape the card renders as a named screen — the two
+    # must never disagree about one token.
+    r = client.post("/auth/password-reset/confirm", json={"token": raw, "password": _NEW})
+    assert r.status_code == 400
+    assert r.json()["detail"] == {"code": "reset", "reason": "invalid"}
+
+
+def test_a_spent_link_is_reported_dead(client, db, make_user):
+    raw = _issue(db, make_user(email="spent@example.com", password=_PW))
+    client.post("/auth/password-reset/confirm", json={"token": raw, "password": _NEW})
+
+    assert client.post("/auth/password-reset/check", json={"token": raw}).json() == {"ok": False}
+
+
+def test_a_too_short_password_does_not_burn_the_link(client, db, make_user):
+    raw = _issue(db, make_user(email="short@example.com", password=_PW))
+
+    r = client.post("/auth/password-reset/confirm", json={"token": raw, "password": "short"})
+
+    assert r.status_code == 400
+    assert r.json()["detail"]["reason"] == "weak_password"
+    # A mistyped password must not cost the link — the length check runs BEFORE the token is spent,
+    # and the card tells the two failures apart by `reason` so only one of them takes the form down.
+    assert client.post(
+        "/auth/password-reset/confirm", json={"token": raw, "password": _NEW}
+    ).json() == {"ok": True}
+
+
+def test_a_dead_verification_link_answers_in_the_same_structured_shape(client):
+    r = client.post("/auth/verify", json={"token": "no-such-token"})
+
+    assert r.status_code == 400
+    assert r.json()["detail"] == {"code": "verify", "reason": "invalid"}
+
+
+def test_the_check_never_reports_a_live_link_dead_when_throttled(
+    client, db, make_user, monkeypatch
+):
+    from app.routes import auth as auth_routes
+
+    raw = _issue(db, make_user(email="throttled@example.com", password=_PW))
+    monkeypatch.setattr(auth_routes._reset_check_limiter, "allow", lambda _ip: False)
+
+    # Fail OPEN. This check may only ever save a wasted form; a throttled probe that answered "dead"
+    # would lock someone out of a link that works.
+    assert client.post("/auth/password-reset/check", json={"token": raw}).json() == {"ok": True}

backend/tests/test_review_round.py

@@ -0,0 +1,350 @@
+"""E9.5 review round — the invariants the epic's own review found unpinned.
+
+Every test here corresponds to a defect a reviewer could still introduce with the whole suite green:
+a mail whose body never renders in any test, an activation that only works for the exact spelling, a
+"we already wrote to them" stamp for a mail that was dropped, an env allow-list that answers a
+different question than the gate it backs, and the address pre-emption that E9.5 S1's argument
+covered only while the address stayed unverified.
+"""
+
+from datetime import datetime, timedelta, timezone
+
+import pytest
+from sqlalchemy import select
+
+from app import auth as auth_core
+from app import email as email_mod
+from app import mailtext
+from app.config import settings
+from app.models import AuthToken, Invite, User
+from app.routes import auth as auth_routes
+
+_PW = "correct horse battery"
+
+
+@pytest.fixture
+def wire(monkeypatch):
+    """Capture what `_send` would have put on the wire. Mails are the one surface where a body that
+    never renders in a test is a body that first renders in someone's inbox."""
+    out: list[tuple[list[str], str, str]] = []
+    monkeypatch.setattr(
+        email_mod,
+        "_send",
+        lambda to, subject, body, reply_to=None: out.append((to, subject, body)) is None,
+    )
+    return out
+
+
+@pytest.fixture
+def smtp_on(monkeypatch):
+    monkeypatch.setattr(email_mod, "email_enabled", lambda db=None: True)
+
+
+# --- every mail actually renders ------------------------------------------------------------------
+
+# One call per `send_*`, with arguments of the right shape. The parity test compares HU against EN
+# and can therefore never catch a template whose placeholders disagree with its CALLER — that
+# mismatch is a KeyError inside a background task, i.e. a mail that silently never goes out. Three
+# mailers this epic rewrote (`password_reset`, `role_changed`, `account_unsuspended`) had no test
+# that executed their `.format()` at all.
+_EVERY_MAIL = [
+    ("send_access_approved", ("to@example.com", "LANG", "https://x/#verify=t", True, 168)),
+    ("send_access_approved", ("to@example.com", "LANG", None, True, 24)),
+    ("send_access_approved", ("to@example.com", "LANG", None, False, 24)),
+    ("send_access_invitation", ("to@example.com", "LANG", "https://x/#verify=t", True, 168)),
+    ("send_access_invitation", ("to@example.com", "LANG", None, False, 24)),
+    ("send_access_denied", ("to@example.com", "LANG")),
+    ("send_role_changed", ("to@example.com", "LANG", "admin", "op@example.com")),
+    ("send_role_changed", ("to@example.com", "LANG", "user", None)),
+    ("send_account_unsuspended", ("to@example.com", "LANG", "op@example.com")),
+    ("send_account_deleted", ("to@example.com", "LANG", None)),
+    ("send_account_suspended", ("to@example.com", "LANG", "op@example.com")),
+    ("send_account_suspended", ("to@example.com", "LANG", None)),
+    ("send_admin_new_request", (["a@example.com"], "LANG", "who@example.com")),
+    ("send_verify_email", ("to@example.com", "LANG", "https://x/#verify=t", 24)),
+    ("send_password_reset", ("to@example.com", "LANG", "https://x/#reset=t")),
+    ("send_test", ("to@example.com", "LANG")),
+]
+
+
+@pytest.mark.parametrize("lang", mailtext.SUPPORTED)
+@pytest.mark.parametrize("name,args", _EVERY_MAIL, ids=[f"{n}{a[2:3]}" for n, a in _EVERY_MAIL])
+def test_every_mail_renders_in_every_language(wire, name, args, lang):
+    getattr(email_mod, name)(*[lang if a == "LANG" else a for a in args])
+
+    (_, subject, body) = wire[0]
+    assert subject and body
+    # A template that lost its interpolation renders the brace text verbatim.
+    assert "{" not in subject and "{" not in body
+
+
+def test_a_weeks_link_is_described_in_days_not_hours(wire):
+    # The S6 approval token lives seven days, and the mail used to say "expires in 168 hours".
+    email_mod.send_access_approved("to@example.com", "en", "https://x/#verify=t", True, 168)
+    assert "7 days" in wire[0][2] and "168" not in wire[0][2]
+
+    email_mod.send_verify_email("to@example.com", "hu", "https://x/#verify=t", 24)
+    assert "24 óra" in wire[1][2]
+
+
+# --- what a second registration may and may not do -------------------------------------------------
+
+
+def test_a_later_registration_never_touches_an_existing_password(db, client, smtp_on, wire):
+    """The rule E9.5's review round 2 put back, having tried the opposite and found it worse.
+
+    "While the address is unverified, the newest registration owns it" looked like a fix for address
+    pre-emption. It is symmetric — an attacker can always be last — so it closed nothing, and it
+    handed an unauthenticated caller the power to overwrite a real registrant's chosen password and
+    delete the confirmation link already sitting in their inbox. On a SEC-10-stripped row it would
+    have installed a password where the whole point is that there is none. Reverted; the owner's
+    recourse is password-reset, which proves the mailbox. Residual logged as SEC-16.
+    """
+    client.post(
+        "/auth/register", json={"email": "victim@example.com", "password": "the first password"}
+    )
+    db.expire_all()
+    user = db.execute(select(User).where(User.email == "victim@example.com")).scalar_one()
+    before = user.password_hash
+
+    client.post(
+        "/auth/register", json={"email": "victim@example.com", "password": "the second password"}
+    )
+
+    db.expire_all()
+    assert db.get(User, user.id).password_hash == before
+
+
+def test_a_later_registration_leaves_a_link_already_in_flight_alive(db, client, smtp_on, wire):
+    client.post(
+        "/auth/register", json={"email": "victim@example.com", "password": "the first password"}
+    )
+    db.expire_all()
+    user = db.execute(select(User).where(User.email == "victim@example.com")).scalar_one()
+    first = db.execute(select(AuthToken.id).where(AuthToken.user_id == user.id)).scalars().all()
+    # Not just a subset check below: `set() <= set()` is vacuously true, so without this the test
+    # would go green while asserting nothing the day registration stops issuing a token.
+    assert len(first) == 1
+
+    client.post(
+        "/auth/register", json={"email": "victim@example.com", "password": "the second password"}
+    )
+
+    db.expire_all()
+    live = db.execute(select(AuthToken.id).where(AuthToken.user_id == user.id)).scalars().all()
+    # The re-send adds a link; it must not invalidate the one the owner may already be holding.
+    assert set(first) <= set(live) and len(live) == len(first) + 1
+
+
+def test_a_stripped_account_keeps_its_recovery_stamp(db, client, smtp_on, make_user):
+    """Prod carries accounts SEC-10 left with no password and a `password_revoked_at` stamp. That
+    stamp is the only reason password-reset still accepts them; an anonymous POST must not be able to
+    clear it, nor to put a password on a row whose whole state is "there is none"."""
+    stripped = make_user(
+        email="stripped@example.com",
+        password=None,
+        email_verified=False,
+        is_active=True,
+        password_revoked_at=datetime.now(timezone.utc),
+    )
+
+    client.post(
+        "/auth/register", json={"email": "stripped@example.com", "password": "an attacker password"}
+    )
+
+    db.expire_all()
+    row = db.get(User, stripped.id)
+    assert row.password_hash is None and row.password_revoked_at is not None
+
+
+def test_a_denied_sibling_is_not_reopened_while_a_pending_row_exists(db, client):
+    # Canonical siblings exist on prod. Picking the denied one reopens it and re-notifies every
+    # admin, putting one person in the queue twice — and the exact-spelling tie-break made that
+    # deterministic rather than merely possible.
+    db.add_all(
+        [
+            Invite(email="pair.one@gmail.com", status="pending"),
+            Invite(email="pairone@gmail.com", status="denied"),
+        ]
+    )
+    db.commit()
+
+    client.post("/auth/request-access", json={"email": "pairone@gmail.com"})
+
+    db.expire_all()
+    rows = {i.email: i.status for i in db.execute(select(Invite)).scalars().all()}
+    assert rows == {"pair.one@gmail.com": "pending", "pairone@gmail.com": "denied"}
+
+
+# --- the env bootstrap answers the same question as the gate --------------------------------------
+
+
+def test_the_env_allow_list_is_matched_canonically(db, monkeypatch):
+    # An operator writing the dotted spelling into ALLOWED_EMAILS was refused when Google answered
+    # with the undotted primary — the 2026-09-03 lockout, on the bootstrap path.
+    monkeypatch.setattr(settings, "allowed_emails", "first.last@gmail.com")
+
+    assert auth_core.is_allowed(db, "firstlast@gmail.com") is True
+    assert auth_core.is_allowed(db, "first.last+tag@gmail.com") is True
+    assert auth_core.is_allowed(db, "someone.else@gmail.com") is False
+
+
+def test_an_env_granted_address_cannot_be_shadowed_by_a_stranger(db, client, monkeypatch):
+    # `is_allowed` short-circuits on ANY invite row for the canonical form, so before this an
+    # unauthenticated caller could request access under a sibling spelling and permanently shadow an
+    # env grant. With the env list matched canonically the request never opens a row.
+    monkeypatch.setattr(settings, "allowed_emails", "bob@gmail.com")
+
+    client.post("/auth/request-access", json={"email": "b.ob@gmail.com"})
+
+    assert db.execute(select(Invite)).scalars().all() == []
+    assert auth_core.is_allowed(db, "bob@gmail.com") is True
+
+
+def test_a_dotted_admin_emails_entry_still_bootstraps_its_admin(monkeypatch):
+    monkeypatch.setattr(settings, "admin_emails", "the.operator+siftlode@gmail.com")
+
+    assert "theoperator@gmail.com" in auth_core.env_admin_canonicals()
+
+
+# --- approving decides about a MAILBOX, not a spelling --------------------------------------------
+
+
+def test_approving_one_spelling_activates_the_account_registered_under_another(
+    db, make_user, as_user, smtp_on, wire
+):
+    # The 2026-09-03 incident in one test: the admin approves the address as typed into the request,
+    # and the account exists under the other Gmail spelling of the same mailbox.
+    admin = make_user(email="admin@example.com", role="admin")
+    user = make_user(email="dotless@gmail.com", password=_PW, is_active=False)
+    user.email = "dotless@gmail.com"
+    inv = Invite(email="dot.less@gmail.com", status="pending")
+    db.add(inv)
+    db.commit()
+
+    r = as_user(admin).post(f"/api/admin/invites/{inv.id}/approve")
+
+    assert r.status_code == 200
+    db.expire_all()
+    assert db.get(User, user.id).is_active is True
+
+
+def test_deleting_one_of_two_accounts_leaves_the_other_one_allowed(db, make_user, as_user):
+    # Prod carries two accounts for one Gmail mailbox. A canonical invite sweep on delete took the
+    # survivor's grant with it, refusing their next sign-in — this epic's founding bug, self-inflicted.
+    admin = make_user(email="admin@example.com", role="admin")
+    doomed = make_user(email="pair.one@gmail.com", password=_PW)
+    make_user(email="pairone@gmail.com", password=_PW)
+    db.add_all([Invite(email="pair.one@gmail.com", status="approved")])
+    db.commit()
+
+    r = as_user(admin).delete(f"/api/admin/users/{doomed.id}")
+
+    assert r.status_code == 200
+    assert auth_core.is_allowed(db, "pairone@gmail.com") is True
+
+
+# --- a button an admin pressed must not report a send that did not happen -------------------------
+
+
+def test_a_failed_invitation_changes_nothing_the_admin_was_told_about(
+    db, make_user, as_user, smtp_on, monkeypatch
+):
+    monkeypatch.setattr(email_mod, "send_access_invitation", lambda *a, **kw: False)
+    admin = make_user(email="admin@example.com", role="admin")
+    stranger = make_user(
+        email="stranger@example.com", password=_PW, email_verified=False, is_active=False
+    )
+    inv = Invite(email="stranger@example.com", status="approved")
+    db.add(inv)
+    db.commit()
+
+    r = as_user(admin).post(f"/api/admin/invites/{inv.id}/invite", json={"lang": "en"})
+
+    assert r.status_code == 422 and r.json()["detail"]["reason"] == "send_failed"
+    db.expire_all()
+    # The column exists to answer "did I already write to them?", and the UI dims the button and
+    # warns about a second mail on the strength of it. A dropped send must not make it say yes.
+    assert db.get(Invite, inv.id).invited_at is None
+    # And a request the UI reports as a failure must not have let somebody in behind the admin's
+    # back — the activation belongs after a mail that actually left.
+    assert db.get(User, stranger.id).is_active is False
+
+
+def test_a_failed_resend_says_so_instead_of_reporting_ok(
+    db, make_user, as_user, smtp_on, monkeypatch
+):
+    monkeypatch.setattr(email_mod, "send_verify_email", lambda *a, **kw: False)
+    admin = make_user(email="admin@example.com", role="admin")
+    stuck = make_user(email="stuck@example.com", password=_PW, email_verified=False)
+
+    r = as_user(admin).post(f"/api/admin/users/{stuck.id}/resend-verification")
+
+    assert r.status_code == 422 and r.json()["detail"]["reason"] == "send_failed"
+
+
+# --- refusals and links that are already dead ------------------------------------------------------
+
+
+def test_an_expired_reset_link_is_reported_dead_without_being_spent(db, client, make_user):
+    # The endpoint exists because a spent or stale link used to draw the full "set a new password"
+    # form. Expiry is the reason its docstring gives, and it was the one case no test covered.
+    user = make_user(email="late@example.com", password=_PW)
+    raw = auth_routes._issue_token(db, user, "reset", timedelta(hours=1))
+    token = db.execute(select(AuthToken).where(AuthToken.user_id == user.id)).scalar_one()
+    token.expires_at = datetime.now(timezone.utc) - timedelta(minutes=1)
+    db.commit()
+
+    assert client.post("/auth/password-reset/check", json={"token": raw}).json() == {"ok": False}
+    r = client.post(
+        "/auth/password-reset/confirm", json={"token": raw, "password": "a new one 123"}
+    )
+    assert r.status_code == 400
+
+
+def test_a_verify_token_cannot_pass_as_a_reset_link(db, client, make_user):
+    user = make_user(email="mixed@example.com", password=_PW)
+    raw = auth_routes._issue_token(db, user, "verify", timedelta(hours=1))
+
+    assert client.post("/auth/password-reset/check", json={"token": raw}).json() == {"ok": False}
+
+
+def test_a_throttled_login_says_nothing_about_the_account(db, client, make_user, monkeypatch):
+    # The two refusals that answer BEFORE the password is proven must stay byte-identical for a real
+    # account and an unknown one; only `invalid` was pinned.
+    make_user(email="real@example.com", password=_PW)
+    monkeypatch.setattr(auth_routes._login_limiter, "allow", lambda key: False)
+
+    real = client.post("/auth/password-login", json={"email": "real@example.com", "password": _PW})
+    unknown = client.post(
+        "/auth/password-login", json={"email": "nobody@example.com", "password": _PW}
+    )
+
+    assert real.status_code == unknown.status_code == 429
+    assert real.json() == unknown.json() == {"detail": {"code": "login", "reason": "rate_limited"}}
+
+
+# --- admins hear about a request in their own language --------------------------------------------
+
+
+def test_two_admins_two_languages_two_mails(db, client, make_user, smtp_on, wire):
+    make_user(email="hu.admin@example.com", role="admin", preferences={"language": "hu"})
+    make_user(email="en.admin@example.com", role="admin", preferences={"language": "en"})
+
+    client.post("/auth/request-access", json={"email": "asking@example.com", "lang": "en"})
+
+    notices = [w for w in wire if "asking@example.com" in w[1]]
+    assert len(notices) == 2
+    by_recipient = {w[0][0]: w[1] for w in notices}
+    assert by_recipient["hu.admin@example.com"] == mailtext.MAIL_TEXT["admin_new_request.subject"][
+        "hu"
+    ].format(requester="asking@example.com")
+    assert by_recipient["en.admin@example.com"] == mailtext.MAIL_TEXT["admin_new_request.subject"][
+        "en"
+    ].format(requester="asking@example.com")
+
+
+def test_an_env_admin_without_an_account_is_written_to_in_the_default(db, monkeypatch):
+    monkeypatch.setattr(settings, "admin_emails", "bootstrap@example.com")
+
+    assert auth_routes.admin_notify_groups(db) == {mailtext.DEFAULT: ["bootstrap@example.com"]}

backend/tests/test_tag_suggest.py

@@ -0,0 +1,286 @@
+"""DB-backed regression (E8·S4): the manual-tag-pattern suggester.
+
+compute_tag_suggestions learns which auto TOPIC tags are *characteristic* of each user tag (from the
+channels the user tagged), then proposes that tag for still-untagged subscribed channels whose own
+topics cover ≥60% of the profile. The cases below pin the behaviours that would silently ship a
+useless suggester if they broke: the min-examples floor, the intersection-over-profile fraction that
+keeps a weak partial match out, the "language is not a signal" exclusion (its inclusion once flooded
+every channel with a suggestion), and the "already tagged → excluded" scope. Deterministic — no
+network, pure DB state.
+
+Uses the DB lane (`db` fixture) — skipped when no Postgres is reachable.
+"""
+
+from app.models import Channel, ChannelTag, Subscription, Tag, User
+from app.sync.tagsuggest import (
+    AUTOAPPLY_THRESHOLD,
+    CHAR_SUPPORT,
+    MAX_PER_CHANNEL,
+    SUGGEST_THRESHOLD,
+    compute_tag_suggestions,
+)
+
+
+def _auto(db, name, category="topic"):
+    tag = Tag(user_id=None, name=name, category=category)
+    db.add(tag)
+    db.flush()
+    return tag
+
+
+def _subscribe(db, user, ch_id, *, auto_tag_ids=(), title=None, hidden=False):
+    """A subscribed channel carrying the given auto-tags (source='auto', user_id NULL)."""
+    db.add(Channel(id=ch_id, title=title or ch_id))
+    db.add(Subscription(user_id=user.id, channel_id=ch_id, hidden=hidden))
+    for tid in auto_tag_ids:
+        db.add(ChannelTag(channel_id=ch_id, tag_id=tid, user_id=None, source="auto"))
+
+
+def test_suggests_a_user_tag_for_a_channel_matching_its_topic_profile(db):
+    me = User(email="me@example.com")
+    db.add(me)
+    db.flush()
+    edu = _auto(db, "Education")
+    film = _auto(db, "Film")
+    eng = _auto(db, "English", category="language")  # a language auto-tag → NOT part of the signal
+    docu = Tag(user_id=me.id, name="docu", category="other")
+    db.add(docu)
+    db.flush()
+
+    # Three example channels the user tagged "docu", all Education+Film (+English). The topic profile
+    # is {Education, Film}; the English language tag is excluded from the profile.
+    for i in range(3):
+        cid = f"UC_ex{i}"
+        _subscribe(db, me, cid, auto_tag_ids=[edu.id, film.id, eng.id])
+        db.add(ChannelTag(channel_id=cid, tag_id=docu.id, user_id=me.id, source="user"))
+
+    # An untagged subscribed channel sharing the full topic profile → full-confidence suggestion.
+    _subscribe(db, me, "UC_match", auto_tag_ids=[edu.id, film.id, eng.id])
+    # An untagged channel sharing ONLY the language → no topic overlap at all, so no suggestion. This
+    # is the anti-flood guarantee: a shared language must never carry a suggestion on its own.
+    _subscribe(db, me, "UC_english_only", auto_tag_ids=[eng.id])
+    db.commit()
+
+    out = compute_tag_suggestions(db, me)
+
+    assert "UC_match" in out
+    assert out["UC_match"][0]["tag_id"] == docu.id
+    # Both profile topics present → full confidence, i.e. an "accept all confident" hit.
+    assert out["UC_match"][0]["confidence"] >= AUTOAPPLY_THRESHOLD
+    assert "UC_english_only" not in out
+    # Example channels are already tagged → excluded from suggestions.
+    assert "UC_ex0" not in out
+
+
+def test_a_tag_below_the_example_floor_produces_no_profile(db):
+    me = User(email="me2@example.com")
+    db.add(me)
+    db.flush()
+    edu = _auto(db, "Education")
+    niche = Tag(user_id=me.id, name="niche", category="other")
+    db.add(niche)
+    db.flush()
+
+    # Only TWO example channels for "niche" (< MIN_EXAMPLES=3) → no profile, so no suggestion even
+    # for a perfectly-matching untagged channel.
+    for i in range(2):
+        cid = f"UC_niche{i}"
+        _subscribe(db, me, cid, auto_tag_ids=[edu.id])
+        db.add(ChannelTag(channel_id=cid, tag_id=niche.id, user_id=me.id, source="user"))
+    _subscribe(db, me, "UC_would_match", auto_tag_ids=[edu.id])
+    db.commit()
+
+    assert compute_tag_suggestions(db, me) == {}
+
+
+def test_partial_topic_overlap_is_a_fraction_of_the_profile(db):
+    # Guards the intersection-over-profile shape at the SUGGEST_THRESHOLD boundary: a 3-topic profile
+    # matched by 1 topic scores 0.33 (dropped); matched by 2 scores 0.67 (kept). Pins the threshold
+    # so a change to it can't silently widen/narrow what "a suggestion" means.
+    assert SUGGEST_THRESHOLD == 0.6
+    me = User(email="me3@example.com")
+    db.add(me)
+    db.flush()
+    a, b, c = _auto(db, "A"), _auto(db, "B"), _auto(db, "C")
+    tag = Tag(user_id=me.id, name="triad", category="other")
+    db.add(tag)
+    db.flush()
+    for i in range(3):
+        cid = f"UC_triad{i}"
+        _subscribe(db, me, cid, auto_tag_ids=[a.id, b.id, c.id])
+        db.add(ChannelTag(channel_id=cid, tag_id=tag.id, user_id=me.id, source="user"))
+    _subscribe(db, me, "UC_one_of_three", auto_tag_ids=[a.id])  # 1/3 = 0.33 < 0.6 → dropped
+    _subscribe(db, me, "UC_two_of_three", auto_tag_ids=[a.id, b.id])  # 2/3 = 0.67 ≥ 0.6 → kept
+    db.commit()
+
+    out = compute_tag_suggestions(db, me)
+    assert "UC_one_of_three" not in out
+    assert "UC_two_of_three" in out
+    assert out["UC_two_of_three"][0]["tag_id"] == tag.id
+    assert out["UC_two_of_three"][0]["confidence"] == round(2 / 3, 3)
+
+
+def test_language_alone_is_never_a_profile_even_when_it_is_the_only_shared_tag(db):
+    # The anti-flood invariant WITH TEETH. Every example channel shares only a language; each carries a
+    # DIFFERENT topic, so no topic reaches CHAR_SUPPORT → the topic-only profile is empty → no
+    # suggestion. If language were ever admitted to the signal the profile would collapse to {language}
+    # and the language-only channel would score 1.0 and be suggested — the exact flood the exclusion
+    # prevents. (test_suggests_… can't catch a regression here: there the language merely enlarges an
+    # already topic-driven profile, so removing the exclusion flips no assertion.)
+    me = User(email="lang@example.com")
+    db.add(me)
+    db.flush()
+    eng = _auto(db, "English", category="language")
+    topics = [_auto(db, f"Topic{i}") for i in range(3)]
+    lang = Tag(user_id=me.id, name="english-stuff", category="other")
+    db.add(lang)
+    db.flush()
+    for i in range(3):
+        cid = f"UC_lang_ex{i}"
+        _subscribe(db, me, cid, auto_tag_ids=[eng.id, topics[i].id])
+        db.add(ChannelTag(channel_id=cid, tag_id=lang.id, user_id=me.id, source="user"))
+    _subscribe(db, me, "UC_lang_only", auto_tag_ids=[eng.id])
+    db.commit()
+
+    # No characteristic topic → no profile → nothing suggested for anyone (language never carries it).
+    assert compute_tag_suggestions(db, me) == {}
+
+
+def test_char_support_admits_a_two_thirds_topic_and_excludes_a_one_third_topic(db):
+    # Pins the characteristic-profile threshold (CHAR_SUPPORT) at its PARTIAL-support boundary: across 3
+    # example channels a topic in 2/3 (0.67 ≥ 0.6) enters the profile, one in 1/3 (0.33) does not. The
+    # other fixtures give every topic full 3/3 support, so a regression demanding full support (or
+    # flipping ≥ to >) would ship green — this is the only case that exercises fractional support.
+    assert CHAR_SUPPORT == 0.6
+    me = User(email="chr@example.com")
+    db.add(me)
+    db.flush()
+    p, q, r = _auto(db, "P"), _auto(db, "Q"), _auto(db, "R")
+    mix = Tag(user_id=me.id, name="mix", category="other")
+    db.add(mix)
+    db.flush()
+    # p in 3/3 (kept), q in 2/3 (kept, 0.67), r in 1/3 (excluded, 0.33) → profile = {p, q}.
+    example_topics = [[p.id, q.id, r.id], [p.id, q.id], [p.id]]
+    for i, topics in enumerate(example_topics):
+        cid = f"UC_mix_ex{i}"
+        _subscribe(db, me, cid, auto_tag_ids=topics)
+        db.add(ChannelTag(channel_id=cid, tag_id=mix.id, user_id=me.id, source="user"))
+    _subscribe(db, me, "UC_pq", auto_tag_ids=[p.id, q.id])  # {p,q}/{p,q} = 1.0 → suggested
+    _subscribe(db, me, "UC_only_p", auto_tag_ids=[p.id])  # 1/2 = 0.5 < 0.6 → dropped
+    _subscribe(db, me, "UC_p_and_r", auto_tag_ids=[p.id, r.id])  # {p}/{p,q} = 0.5 → dropped
+    db.commit()
+
+    out = compute_tag_suggestions(db, me)
+    assert "UC_pq" in out and out["UC_pq"][0]["confidence"] == 1.0
+    # q (2/3) IS in the profile: p alone covers only half of it. Would be a full 1.0 match if the
+    # builder wrongly required 3/3 support (profile would collapse to {p}).
+    assert "UC_only_p" not in out
+    # r (1/3) is NOT in the profile: {p,r} covers only p. Would score 0.67 (suggested) if r wrongly
+    # entered the profile (a downward drift of CHAR_SUPPORT).
+    assert "UC_p_and_r" not in out
+
+
+def test_suggestions_are_capped_and_ordered_best_first(db):
+    # A channel matching many user-tag profiles gets at most MAX_PER_CHANNEL suggestions, ordered best
+    # score first, with the weakest dropped by the cap. No other fixture matches >1 profile, so the sort
+    # and the cap are both no-ops there — dropping either ships green. Four DISTINCT confidences keep the
+    # order unambiguous. (The exact-tie tag_id tie-break in the sort key is a determinism detail, not
+    # asserted here: on a stable sort it isn't catchable without relying on unspecified DB row order.)
+    me = User(email="cap@example.com")
+    db.add(me)
+    db.flush()
+
+    def profile_tag(name, n_topics):
+        """A user tag whose characteristic profile is exactly n_topics (3 identical example channels)."""
+        topics = [_auto(db, f"{name}_t{i}") for i in range(n_topics)]
+        tag = Tag(user_id=me.id, name=name, category="other")
+        db.add(tag)
+        db.flush()
+        for i in range(3):
+            cid = f"UC_{name}_ex{i}"
+            _subscribe(db, me, cid, auto_tag_ids=[t.id for t in topics])
+            db.add(ChannelTag(channel_id=cid, tag_id=tag.id, user_id=me.id, source="user"))
+        return tag, topics
+
+    t0, top0 = profile_tag("p0", 1)  # profile size 1
+    t1, top1 = profile_tag("p1", 5)  # profile size 5
+    t2, top2 = profile_tag("p2", 10)  # profile size 10
+    t3, top3 = profile_tag("p3", 10)  # profile size 10
+
+    # One untagged channel matching all four at distinct confidences:
+    #   t0: 1/1  = 1.00
+    #   t1: 4/5  = 0.80
+    #   t2: 7/10 = 0.70
+    #   t3: 6/10 = 0.60  → a valid hit (≥ SUGGEST_THRESHOLD) but the weakest, dropped by the cap of 3
+    matched = (
+        [top0[0].id]
+        + [t.id for t in top1[:4]]
+        + [t.id for t in top2[:7]]
+        + [t.id for t in top3[:6]]
+    )
+    _subscribe(db, me, "UC_many", auto_tag_ids=matched)
+    db.commit()
+
+    hits = compute_tag_suggestions(db, me)["UC_many"]
+    assert len(hits) == MAX_PER_CHANNEL  # 4 matches, capped to 3
+    assert [h["tag_id"] for h in hits] == [t0.id, t1.id, t2.id]  # best score first
+    assert [h["confidence"] for h in hits] == [1.0, 0.8, 0.7]
+    assert t3.id not in [
+        h["tag_id"] for h in hits
+    ]  # the weakest match (0.60) is the one the cap drops
+
+
+def test_unsubscribed_example_channel_does_not_inflate_the_profile_denominator(db):
+    # Unsubscribe deletes the Subscription but NOT the source='user' ChannelTag, so a tagged-then-
+    # unsubscribed channel must NOT count as a profile example: it contributes no topic features (those
+    # are scanned over subscribed channels only) yet would inflate CHAR_SUPPORT's denominator and drop a
+    # genuinely characteristic topic. Here 'X' is characteristic at 2/3 of the SUBSCRIBED examples
+    # (threshold 1.8, count 2 → kept), but if the unsubscribed 4th example counted, threshold 2.4 would
+    # drop it and suppress the suggestion.
+    me = User(email="unsub@example.com")
+    db.add(me)
+    db.flush()
+    x, y = _auto(db, "X"), _auto(db, "Y")
+    wood = Tag(user_id=me.id, name="wood", category="other")
+    db.add(wood)
+    db.flush()
+    # 3 subscribed examples: 2 carry topic X, 1 carries only Y → X support 2/3 among subscribed.
+    for cid, topic in [("UC_w0", x), ("UC_w1", x), ("UC_w2", y)]:
+        _subscribe(db, me, cid, auto_tag_ids=[topic.id])
+        db.add(ChannelTag(channel_id=cid, tag_id=wood.id, user_id=me.id, source="user"))
+    # A 4th channel tagged "wood" but NO LONGER subscribed (channel + user tag, no Subscription row).
+    db.add(Channel(id="UC_gone", title="UC_gone"))
+    db.add(ChannelTag(channel_id="UC_gone", tag_id=wood.id, user_id=me.id, source="user"))
+    _subscribe(
+        db, me, "UC_cand", auto_tag_ids=[x.id]
+    )  # untagged X match → should be suggested "wood"
+    db.commit()
+
+    out = compute_tag_suggestions(db, me)
+    assert "UC_cand" in out
+    assert out["UC_cand"][0]["tag_id"] == wood.id
+
+
+def test_hidden_subscriptions_are_not_suggestion_targets(db):
+    # The Channel Manager renders suggestion ghost chips only on non-hidden rows, so a hidden channel
+    # must not be a suggestion target — otherwise the header count / bulk-accept would span channels with
+    # no visible chip. (Hidden channels still count as example/feature signal; only targeting is excluded.)
+    me = User(email="hid@example.com")
+    db.add(me)
+    db.flush()
+    z = _auto(db, "Z")
+    ztag = Tag(user_id=me.id, name="ztag", category="other")
+    db.add(ztag)
+    db.flush()
+    for i in range(3):
+        cid = f"UC_z{i}"
+        _subscribe(db, me, cid, auto_tag_ids=[z.id])
+        db.add(ChannelTag(channel_id=cid, tag_id=ztag.id, user_id=me.id, source="user"))
+    # A hidden, untagged, perfectly-matching subscription → NOT a target; a visible one → suggested.
+    _subscribe(db, me, "UC_hidden", auto_tag_ids=[z.id], hidden=True)
+    _subscribe(db, me, "UC_visible", auto_tag_ids=[z.id])
+    db.commit()
+
+    out = compute_tag_suggestions(db, me)
+    assert "UC_visible" in out
+    assert "UC_hidden" not in out

backend/tests/test_upload.py

@@ -0,0 +1,503 @@
+"""E7 S5a — local file upload ingest (the non-yt-dlp path into the media library).
+
+Covers the ingest spine: media vs generic-file classification, the download-only serving of a
+generic file (force-download so uploaded HTML/SVG can't execute inline), quota accounting with the
+size known up front, the per-file cap enforced while streaming, filename sanitization, and the two
+guards that keep an upload out of paths that assume a re-fetchable source (edit / redownload).
+
+DB-backed (real Postgres) — skipped when no database is reachable. `settings.download_root` is
+pointed at a per-test tmp dir so ingest's on-disk moves are isolated. The ingest/route tests
+monkeypatch the shared `probe.probe_media` so they don't shell out to ffprobe; the classifier's OWN
+parsing (image → file, cover-art skip, dims, duration) is covered directly by `TestProbeClassifier`
+below, which stubs one level down (`run_ffprobe_json`) and exercises the real `probe_media`.
+"""
+
+from pathlib import Path
+
+import pytest
+
+from app.config import settings
+from app.downloads import mediakind, quota, storage
+from app.downloads import probe as probemod
+from app.downloads import upload as uploadmod
+from app.models import DownloadQuota, MediaAsset
+
+
+# --- pure: the kind invariant ---------------------------------------------------------------
+
+
+def test_derive_media_kind():
+    assert uploadmod.mediakind.derive("h264", "aac") == mediakind.VIDEO
+    assert uploadmod.mediakind.derive("vp9", None) == mediakind.VIDEO
+    assert uploadmod.mediakind.derive(None, "aac") == mediakind.AUDIO
+    assert uploadmod.mediakind.derive(None, None) == mediakind.FILE
+
+
+# --- ingest (direct) ------------------------------------------------------------------------
+
+
+@pytest.fixture
+def _root(tmp_path, monkeypatch):
+    monkeypatch.setattr(settings, "download_root", str(tmp_path))
+    return tmp_path
+
+
+def _probe(monkeypatch, result):
+    # upload ingest now calls the shared `probe.probe_media` (same ground-truth ffprobe the download
+    # worker uses); patch it at that shared home.
+    monkeypatch.setattr(probemod, "probe_media", lambda _p: result)
+
+
+def test_ingest_generic_file_is_download_only(db, make_user, _root, monkeypatch):
+    _probe(monkeypatch, (None, None, None, None, None))
+    u = make_user()
+    src = _root / "src.bin"
+    src.write_bytes(b"%PDF-1.4 hello")
+    job = uploadmod.ingest_upload(
+        db, u.id, filename="My Notes.pdf", src_path=src, size=src.stat().st_size
+    )
+    asset = db.get(MediaAsset, job.asset_id)
+    assert asset.media_kind == mediakind.FILE
+    assert asset.status == "ready" and job.status == "done" and job.progress == 100
+    assert asset.container == "pdf"
+    assert asset.poster_path is None  # a generic file has no player and no poster
+    assert asset.title == "My Notes"  # display title from the original name
+    assert job.job_kind == "upload" and job.source_kind == "upload"
+    # The file was MOVED into the per-user uploads tree, inside the root, and the temp is gone.
+    assert not src.exists()
+    assert asset.rel_path.startswith(".uploads/")
+    assert storage.safe_abs_path(str(_root), asset.rel_path) is not None
+
+
+def test_ingest_audio_is_media_no_poster(db, make_user, _root, monkeypatch):
+    _probe(monkeypatch, (None, "aac", None, None, 200))
+    u = make_user()
+    src = _root / "song.m4a"
+    src.write_bytes(b"fake-audio")
+    job = uploadmod.ingest_upload(db, u.id, filename="song.m4a", src_path=src, size=10)
+    asset = db.get(MediaAsset, job.asset_id)
+    assert asset.media_kind == mediakind.AUDIO
+    assert asset.duration_s == 200
+    assert asset.poster_path is None  # audio has no frame to poster
+
+
+def test_ingest_video_records_dims_and_poster(db, make_user, _root, monkeypatch):
+    _probe(monkeypatch, ("h264", "aac", 640, 480, 60))
+    # Stub the frame-cut so the test doesn't shell out to ffmpeg.
+    monkeypatch.setattr(uploadmod.editmod, "ensure_poster", lambda _a, _root: "p/x.jpg")
+    u = make_user()
+    src = _root / "clip.mp4"
+    src.write_bytes(b"fake-video")
+    job = uploadmod.ingest_upload(db, u.id, filename="clip.mp4", src_path=src, size=10)
+    asset = db.get(MediaAsset, job.asset_id)
+    assert asset.media_kind == mediakind.VIDEO
+    assert (asset.width, asset.height) == (640, 480)
+    assert asset.poster_path == "p/x.jpg"
+
+
+def test_ingest_filename_is_sanitized_no_traversal(db, make_user, _root, monkeypatch):
+    _probe(monkeypatch, (None, None, None, None, None))
+    u = make_user()
+    src = _root / "src"
+    src.write_bytes(b"x")
+    job = uploadmod.ingest_upload(db, u.id, filename="../../etc/passwd", src_path=src, size=1)
+    asset = db.get(MediaAsset, job.asset_id)
+    assert ".." not in asset.rel_path
+    assert asset.rel_path.startswith(f".uploads/{u.id}/")
+    assert storage.safe_abs_path(str(_root), asset.rel_path) is not None
+
+
+def test_ingest_rejects_over_footprint_cap_before_writing(db, make_user, _root, monkeypatch):
+    _probe(monkeypatch, (None, None, None, None, None))
+    u = make_user()
+    db.add(
+        DownloadQuota(user_id=u.id, max_bytes=1000, max_concurrent=2, max_jobs=50, unlimited=False)
+    )
+    db.commit()
+    src = _root / "big.bin"
+    src.write_bytes(b"x" * 10)
+    with pytest.raises(quota.QuotaExceeded) as e:
+        uploadmod.ingest_upload(db, u.id, filename="big.bin", src_path=src, size=2000)
+    assert e.value.reason == "max_bytes"
+    assert src.exists()  # rejected before any disk move — nothing landed
+    assert db.query(MediaAsset).count() == 0  # and no orphan asset row
+
+
+# --- route ----------------------------------------------------------------------------------
+
+
+def test_upload_route_generic_forces_download(as_user, make_user, _root, monkeypatch):
+    _probe(monkeypatch, (None, None, None, None, None))
+    c = as_user(make_user())
+    r = c.post(
+        "/api/downloads/upload",
+        files={"file": ("report.html", b"<script>alert(1)</script>", "text/html")},
+    )
+    assert r.status_code == 200, r.text
+    job = r.json()
+    assert job["asset"]["media_kind"] == "file"
+    assert job["can_download"] is True
+    # The served file must be a neutral force-download attachment — never inline text/html.
+    fr = c.get(f"/api/downloads/{job['id']}/file")
+    assert fr.status_code == 200
+    assert fr.headers["content-type"].startswith("application/octet-stream")
+    assert "attachment" in fr.headers["content-disposition"].lower()
+
+
+def test_upload_route_media_html_extension_not_served_as_html(
+    as_user, make_user, _root, monkeypatch
+):
+    """The XSS guard: a MEDIA-classified upload (real codecs) named with an executable extension must
+    NOT be served with a guessed text/html type. The served Content-Type comes from the verified
+    media_kind + a container allow-list ('html' isn't one), so it force-downloads as octet-stream —
+    on both the authenticated file endpoint AND the login-free public watch endpoint. Without the fix
+    the public inline branch let a media/HTML polyglot named evil.html run as stored XSS."""
+    _probe(monkeypatch, ("h264", "aac", 320, 240, 5))  # ffprobe says it's video…
+    c = as_user(make_user())
+    r = c.post(
+        "/api/downloads/upload",
+        files={"file": ("evil.html", b"<script>alert(1)</script>", "text/html")},
+    )
+    assert r.status_code == 200, r.text
+    job = r.json()
+    assert job["asset"]["media_kind"] == "video" and job["asset"]["container"] == "html"
+
+    # Authenticated endpoint: never text/html.
+    fr = c.get(f"/api/downloads/{job['id']}/file")
+    assert fr.status_code == 200
+    assert fr.headers["content-type"].startswith("application/octet-stream")
+    assert "attachment" in fr.headers["content-disposition"].lower()
+
+    # Public login-free endpoint via a STREAM-ONLY link (the inline branch) — still not text/html.
+    link = c.post(f"/api/downloads/{job['id']}/links", json={"allow_download": False}).json()
+    pr = c.get(f"/api/public/watch/{link['token']}/file")
+    assert pr.status_code == 200
+    assert not pr.headers["content-type"].startswith("text/html")
+    assert pr.headers["content-type"].startswith("application/octet-stream")
+    assert "attachment" in pr.headers["content-disposition"].lower()
+
+
+def test_public_watch_file_forces_download_for_generic_file(as_user, make_user, _root, monkeypatch):
+    """The login-free public serve of a generic upload (media_kind='file') must be a neutral
+    force-download attachment — the branch that stops uploaded HTML/SVG executing on the public
+    origin. This is a SEPARATE code path from the authenticated /file route, so it needs its own
+    route-level assertion (previously only the authenticated branch was tested)."""
+    _probe(monkeypatch, (None, None, None, None, None))
+    c = as_user(make_user())
+    job = c.post(
+        "/api/downloads/upload",
+        files={"file": ("notes.html", b"<script>alert(1)</script>", "text/html")},
+    ).json()
+    assert job["asset"]["media_kind"] == "file"
+    link = c.post(f"/api/downloads/{job['id']}/links", json={"allow_download": True}).json()
+    pr = c.get(f"/api/public/watch/{link['token']}/file")
+    assert pr.status_code == 200
+    assert pr.headers["content-type"].startswith("application/octet-stream")
+    assert "attachment" in pr.headers["content-disposition"].lower()
+
+
+def test_public_watch_file_serves_media_inline_with_real_type(
+    as_user, make_user, _root, monkeypatch
+):
+    """A recognised media container IS still served inline with its real audio/video type (so it
+    plays in the watch page) — the fix must not break legitimate playback. A stream-only link →
+    inline; the type is video/mp4 (from the container allow-list), never text/* and never a guess."""
+    _probe(monkeypatch, ("h264", "aac", 640, 360, 12))
+    c = as_user(make_user())
+    job = c.post(
+        "/api/downloads/upload",
+        files={"file": ("clip.mp4", b"fake-mp4-bytes", "video/mp4")},
+    ).json()
+    link = c.post(f"/api/downloads/{job['id']}/links", json={"allow_download": False}).json()
+    pr = c.get(f"/api/public/watch/{link['token']}/file")
+    assert pr.status_code == 200
+    assert pr.headers["content-type"].startswith("video/mp4")
+    assert "inline" in pr.headers["content-disposition"].lower()
+
+
+def test_upload_route_enforces_per_file_cap(as_user, make_user, db, _root, monkeypatch):
+    from app import sysconfig
+
+    sysconfig.set_value(db, "download_upload_max_bytes", 5)
+    db.commit()
+    c = as_user(make_user())
+    r = c.post(
+        "/api/downloads/upload",
+        files={"file": ("big.bin", b"way over the cap", "application/octet-stream")},
+    )
+    assert r.status_code == 422
+    assert r.json()["detail"]["code"] == "upload_too_large"
+
+
+def test_upload_cap_cannot_be_disabled_with_zero(db):
+    """download_upload_max_bytes floors at 1: a stored 0 would read falsy in the route's
+    `if cap and size > cap` guard and SILENTLY disable the per-file cap, so set_value must reject it.
+    Pins the min=1 invariant so a revert to min=0 can't pass the gate."""
+    from app import sysconfig
+
+    with pytest.raises(ValueError):
+        sysconfig.set_value(db, "download_upload_max_bytes", 0)
+
+
+def test_upload_route_rejects_empty_file(as_user, make_user, _root, monkeypatch):
+    c = as_user(make_user())
+    r = c.post(
+        "/api/downloads/upload", files={"file": ("empty.bin", b"", "application/octet-stream")}
+    )
+    assert r.status_code == 400
+    assert r.json()["detail"]["code"] == "upload_empty"
+
+
+def test_redownload_rejects_an_upload(as_user, make_user, _root, monkeypatch):
+    _probe(monkeypatch, (None, None, None, None, None))
+    c = as_user(make_user())
+    job = c.post(
+        "/api/downloads/upload", files={"file": ("a.bin", b"data", "application/octet-stream")}
+    ).json()
+    r = c.post(f"/api/downloads/{job['id']}/redownload")
+    assert r.status_code == 409
+
+
+def test_edit_rejects_a_generic_upload_source(as_user, make_user, _root, monkeypatch):
+    _probe(monkeypatch, (None, None, None, None, None))
+    c = as_user(make_user())
+    job = c.post(
+        "/api/downloads/upload", files={"file": ("a.bin", b"data", "application/octet-stream")}
+    ).json()
+    r = c.post(
+        "/api/downloads/edit",
+        json={"source_job_id": job["id"], "edit_spec": {"trim": {"start_s": 0, "end_s": 1}}},
+    )
+    assert r.status_code == 400
+    assert r.json()["detail"]["reason"] == "not_media"
+
+
+def test_ingest_rejects_over_max_jobs(db, make_user, _root, monkeypatch):
+    """The other check_upload rejection branch (holdings count, not bytes): once the user is at
+    max_jobs, a further upload is refused before any disk write."""
+    _probe(monkeypatch, (None, None, None, None, None))
+    u = make_user()
+    db.add(
+        DownloadQuota(user_id=u.id, max_bytes=10**12, max_concurrent=2, max_jobs=1, unlimited=False)
+    )
+    db.commit()
+    src1 = _root / "a.bin"
+    src1.write_bytes(b"a")
+    uploadmod.ingest_upload(db, u.id, filename="a.bin", src_path=src1, size=1)  # now 1 holding job
+    src2 = _root / "b.bin"
+    src2.write_bytes(b"b")
+    with pytest.raises(quota.QuotaExceeded) as e:
+        uploadmod.ingest_upload(db, u.id, filename="b.bin", src_path=src2, size=1)
+    assert e.value.reason == "max_jobs"
+    assert src2.exists()  # rejected before the move — nothing landed
+
+
+def test_ingest_cleans_up_placed_files_on_commit_failure(db, make_user, _root, monkeypatch):
+    """A failure AFTER storage.place_file has moved the file onto disk must roll back AND unlink the
+    placed file + any (even partial) poster — otherwise the orphan is permanent (the per-user delete
+    keys off the rolled-back asset.rel_path, and the GC orphan sweep skips the dot-prefixed .uploads/
+    tree). Exercises the rollback/cleanup branch that IS the leak remediation, incl. the poster case
+    where ensure_poster left a partial file but returned None."""
+    _probe(monkeypatch, ("h264", "aac", 320, 240, 5))  # video → the poster path runs
+    u = make_user()
+
+    # Simulate ffmpeg leaving a partial poster on disk, then failing (ensure_poster returns None).
+    def _partial_poster(asset, root):
+        storage.abs_path(root, str(Path(asset.rel_path).with_suffix(".jpg"))).write_bytes(
+            b"partial"
+        )
+        return None
+
+    monkeypatch.setattr(uploadmod.editmod, "ensure_poster", _partial_poster)
+
+    # Force the commit to fail after the file (and partial poster) are on disk.
+    def _boom():
+        raise RuntimeError("db down")
+
+    monkeypatch.setattr(db, "commit", _boom)
+
+    src = _root / "clip.mp4"
+    src.write_bytes(b"fake-video-bytes")
+    with pytest.raises(RuntimeError):
+        uploadmod.ingest_upload(db, u.id, filename="clip.mp4", src_path=src, size=16)
+
+    db.rollback()  # drop the monkeypatched-commit session state before querying
+    uploads = _root / ".uploads"
+    leftover = [p for p in uploads.rglob("*") if p.is_file()] if uploads.exists() else []
+    assert leftover == [], f"orphaned files left on disk: {leftover}"
+    assert db.query(MediaAsset).count() == 0  # the flushed asset rolled back — no dangling row
+
+
+# --- classifier: the REAL probe_media parsing (stubs ffprobe one level down) ------------------
+# The ingest/route tests above stub probe_media wholesale; these exercise its OWN logic — image
+# detection, the cover-art skip, dimension/duration parsing — by faking only run_ffprobe_json, so a
+# regression in the classifier the force-download guarantee leans on is actually caught.
+
+
+class TestProbeClassifier:
+    def _probe_with(self, monkeypatch, data):
+        monkeypatch.setattr(probemod.editmod, "run_ffprobe_json", lambda *a, **k: data)
+        return probemod.probe_media(Path("x"))
+
+    def test_probe_failure_is_a_generic_file(self, monkeypatch):
+        # run_ffprobe_json returns None (ffprobe failed / not media) → all None → derive() == FILE.
+        v, a, w, h, d = self._probe_with(monkeypatch, None)
+        assert (v, a, w, h, d) == (None, None, None, None, None)
+        assert mediakind.derive(v, a) == mediakind.FILE
+
+    @pytest.mark.parametrize("fmt", ["image2", "png_pipe", "jpeg_pipe", "webp_pipe", "gif"])
+    def test_still_image_classifies_as_file_not_video(self, monkeypatch, fmt):
+        # A standalone image exposes a real video stream, but its container format is an image demuxer
+        # — it must NOT become media_kind='video' (broken player + inline serving). Stays a file.
+        data = {
+            "format": {"format_name": fmt},
+            "streams": [{"codec_type": "video", "codec_name": "png", "width": 8, "height": 8}],
+        }
+        v, a, w, h, d = self._probe_with(monkeypatch, data)
+        assert v is None and mediakind.derive(v, a) == mediakind.FILE
+
+    def test_cover_art_video_stream_is_skipped_audio_stays_audio(self, monkeypatch):
+        # Album art embedded in an audio file is a video stream flagged attached_pic — skip it so the
+        # asset classifies as audio, not video.
+        data = {
+            "format": {"format_name": "mp3", "duration": "212.5"},
+            "streams": [
+                {
+                    "codec_type": "video",
+                    "codec_name": "mjpeg",
+                    "disposition": {"attached_pic": 1},
+                    "width": 600,
+                    "height": 600,
+                },
+                {"codec_type": "audio", "codec_name": "mp3"},
+            ],
+        }
+        v, a, w, h, d = self._probe_with(monkeypatch, data)
+        assert (v, a, d) == (None, "mp3", 212)
+        assert mediakind.derive(v, a) == mediakind.AUDIO
+
+    def test_real_video_records_codecs_dims_duration(self, monkeypatch):
+        data = {
+            "format": {"format_name": "mov,mp4,m4a", "duration": "60.0"},
+            "streams": [
+                {"codec_type": "video", "codec_name": "h264", "width": 1920, "height": 1080},
+                {"codec_type": "audio", "codec_name": "aac"},
+            ],
+        }
+        v, a, w, h, d = self._probe_with(monkeypatch, data)
+        assert (v, a, w, h, d) == ("h264", "aac", 1920, 1080, 60)
+        assert mediakind.derive(v, a) == mediakind.VIDEO
+
+    def test_unparseable_duration_is_none(self, monkeypatch):
+        data = {
+            "format": {"format_name": "wav", "duration": "N/A"},
+            "streams": [{"codec_type": "audio", "codec_name": "pcm_s16le"}],
+        }
+        v, a, w, h, d = self._probe_with(monkeypatch, data)
+        assert d is None and mediakind.derive(v, a) == mediakind.AUDIO
+
+
+# --- resolve_media_facts: probe-of-the-file wins over yt-dlp's info (the FB regression fix) ---------
+# The download worker's finalize must classify from the ACTUAL file, not the extractor's `info` dict.
+# yt-dlp omits vcodec/acodec/dims for some sources (Facebook), and deriving media_kind from those
+# nulls turned a real H.264 video into a download-only 'file' (no in-app play). These pin that the
+# probe is authoritative and `info` is only a gap-filler.
+
+
+class TestResolveMediaFacts:
+    # These stub run_ffprobe_json (one level below probe_media) so the REAL probe parsing + the
+    # probe-vs-info precedence are exercised together — the precedence keys off whether ffprobe RAN.
+    @staticmethod
+    def _ffprobe(monkeypatch, data):
+        monkeypatch.setattr(probemod.editmod, "run_ffprobe_json", lambda *a, **k: data)
+
+    def test_probe_wins_when_info_lacks_codecs(self, monkeypatch):
+        # THE original regression: info has no vcodec/acodec/dims (Facebook), but the file probes as
+        # h264/aac.
+        self._ffprobe(
+            monkeypatch,
+            {
+                "format": {"format_name": "mov,mp4,m4a"},
+                "streams": [
+                    {"codec_type": "video", "codec_name": "h264", "width": 720, "height": 1280},
+                    {"codec_type": "audio", "codec_name": "aac"},
+                ],
+            },
+        )
+        v, a, w, h = probemod.resolve_media_facts(Path("x"), {"width": None, "height": None})
+        assert (v, a, w, h) == ("h264", "aac", 720, 1280)
+        assert mediakind.derive(v, a) == mediakind.VIDEO  # NOT 'file'
+
+    def test_probe_wins_over_a_DIFFERING_populated_info(self, monkeypatch):
+        # Both the probe AND info are populated but DISAGREE (info carries a pre-remux/pre-merge codec).
+        # The finished file on disk is ground truth, so the probe wins outright — pins the precedence a
+        # `info or probe` inversion would silently break.
+        self._ffprobe(
+            monkeypatch,
+            {
+                "format": {"format_name": "mov,mp4,m4a"},
+                "streams": [
+                    {"codec_type": "video", "codec_name": "h264", "width": 1920, "height": 1080},
+                    {"codec_type": "audio", "codec_name": "aac"},
+                ],
+            },
+        )
+        v, a, w, h = probemod.resolve_media_facts(
+            Path("x"), {"vcodec": "vp9", "acodec": "opus", "width": 640, "height": 480}
+        )
+        assert (v, a, w, h) == ("h264", "aac", 1920, 1080)  # probe, not info
+
+    def test_cover_art_audio_download_is_not_resurrected_to_video_by_info(self, monkeypatch):
+        # THE bug this fix targets: an audio-mode download from a progressive source embeds cover art,
+        # and yt-dlp's info still carries the source's video codec. The probe correctly finds only audio
+        # (the attached_pic is skipped); info's vcodec must NOT resurrect a video track → media_kind
+        # stays audio, not a broken in-app 'video'.
+        self._ffprobe(
+            monkeypatch,
+            {
+                "format": {"format_name": "mp3", "duration": "180.0"},
+                "streams": [
+                    {
+                        "codec_type": "video",
+                        "codec_name": "mjpeg",
+                        "disposition": {"attached_pic": 1},
+                    },
+                    {"codec_type": "audio", "codec_name": "mp3"},
+                ],
+            },
+        )
+        v, a, w, h = probemod.resolve_media_facts(
+            Path("x"), {"vcodec": "avc1", "acodec": "mp4a", "width": 1280, "height": 720}
+        )
+        assert v is None and a == "mp3"  # info's avc1 did NOT win
+        assert mediakind.derive(v, a) == mediakind.AUDIO  # NOT VIDEO
+
+    def test_still_image_download_is_not_resurrected_to_video_by_info(self, monkeypatch):
+        # A downloaded still image: the probe returns no vcodec (image-format guard). info's image
+        # "vcodec" must not turn it into a broken 'video' → stays a generic file.
+        self._ffprobe(
+            monkeypatch,
+            {
+                "format": {"format_name": "png_pipe"},
+                "streams": [{"codec_type": "video", "codec_name": "png", "width": 8, "height": 8}],
+            },
+        )
+        v, a, w, h = probemod.resolve_media_facts(
+            Path("x"), {"vcodec": "png", "width": 8, "height": 8}
+        )
+        assert v is None and mediakind.derive(v, a) == mediakind.FILE
+
+    def test_info_fills_in_only_when_ffprobe_could_not_read_the_file(self, monkeypatch):
+        # ffprobe failed entirely (None) → fall back to info so we never regress the working path.
+        self._ffprobe(monkeypatch, None)
+        v, a, w, h = probemod.resolve_media_facts(
+            Path("x"), {"vcodec": "vp9", "acodec": "opus", "width": 1920, "height": 1080}
+        )
+        assert (v, a, w, h) == ("vp9", "opus", 1920, 1080)
+
+    def test_info_none_codec_string_is_treated_as_absent(self, monkeypatch):
+        # yt-dlp writes the literal "none" for a missing stream — it must not become a codec name.
+        self._ffprobe(monkeypatch, None)  # probe failed → info path, where the "none" scrub applies
+        v, a, w, h = probemod.resolve_media_facts(Path("x"), {"vcodec": "none", "acodec": "aac"})
+        assert (v, a) == (None, "aac")
+        assert mediakind.derive(v, a) == mediakind.AUDIO

backend/tests/test_welcome_mail.py

@@ -0,0 +1,249 @@
+"""One mail, one click — the branching welcome/invitation mail (E9.5 S6), DB-lane.
+
+The funnel's common ordering makes a person open TWO messages: one saying their access is approved,
+another asking them to confirm their address. The C option carries the confirmation link inside the
+mail that is already going out, so the usual case is one mail and one click.
+
+Also here: the silent no-op that is the most likely explanation for the 2026-09-03 report that a
+confirmation mail "never arrived". Re-registering an address that already had an unconfirmed account
+sent nothing at all, while answering with the same cheerful "check your inbox".
+"""
+
+from datetime import datetime, timedelta, timezone
+
+from sqlalchemy import select
+
+from app.models import AuditLog, AuthToken, Invite, User
+
+_PW = "correct horse battery"
+
+
+def _capture(monkeypatch, name):
+    """Record the arguments a given email_mod.send_* was called with."""
+    from app import email as email_mod
+
+    calls: list[tuple] = []
+    monkeypatch.setattr(email_mod, name, lambda *a, **kw: calls.append((a, kw)) or True)
+    return calls
+
+
+def _smtp_on(monkeypatch):
+    from app import email as email_mod
+
+    monkeypatch.setattr(email_mod, "email_enabled", lambda db=None: True)
+
+
+def _approve(client, invite_id):
+    r = client.post(f"/api/admin/invites/{invite_id}/approve")
+    assert r.status_code == 200
+    return r
+
+
+# --- the approval mail branches ------------------------------------------------------------------
+
+
+def test_an_unconfirmed_account_gets_the_confirmation_link_in_the_approval_mail(
+    db, make_user, as_user, monkeypatch
+):
+    _smtp_on(monkeypatch)
+    sent = _capture(monkeypatch, "send_access_approved")
+    admin = make_user(email="admin@example.com", role="admin")
+    inv = Invite(email="waiting@example.com", status="pending")
+    db.add(inv)
+    db.commit()
+    make_user(email="waiting@example.com", password=_PW, email_verified=False, is_active=False)
+
+    _approve(as_user(admin), inv.id)
+
+    (email, _lang, link, has_account, hours), _ = sent[0]
+    assert email == "waiting@example.com" and has_account is True
+    assert link and "#verify=" in link
+    # The whole point: this is the ONLY message they now have to open.
+    assert hours == 24 * 7
+
+
+def test_the_link_in_that_mail_actually_confirms_the_address(db, make_user, as_user, monkeypatch):
+    _smtp_on(monkeypatch)
+    sent = _capture(monkeypatch, "send_access_approved")
+    admin = make_user(email="admin@example.com", role="admin")
+    inv = Invite(email="waiting@example.com", status="pending")
+    db.add(inv)
+    db.commit()
+    user = make_user(
+        email="waiting@example.com", password=_PW, email_verified=False, is_active=False
+    )
+    _approve(as_user(admin), inv.id)
+    token = sent[0][0][2].split("#verify=")[1]
+
+    r = as_user(admin).post("/auth/verify", json={"token": token})
+
+    assert r.status_code == 200
+    db.expire_all()
+    assert db.get(User, user.id).email_verified is True
+
+
+def test_that_link_outlives_a_weekend(db, make_user, as_user, monkeypatch):
+    # An approval is not a mail anyone sits waiting for; the standard 24h would routinely expire
+    # before it is read, and the one-mail promise with it.
+    _smtp_on(monkeypatch)
+    _capture(monkeypatch, "send_access_approved")
+    admin = make_user(email="admin@example.com", role="admin")
+    inv = Invite(email="waiting@example.com", status="pending")
+    db.add(inv)
+    db.commit()
+    user = make_user(
+        email="waiting@example.com", password=_PW, email_verified=False, is_active=False
+    )
+
+    _approve(as_user(admin), inv.id)
+
+    tok = db.execute(select(AuthToken).where(AuthToken.user_id == user.id)).scalars().all()[-1]
+    assert tok.expires_at > datetime.now(timezone.utc) + timedelta(days=6)
+
+
+def test_an_already_confirmed_account_is_just_told_to_sign_in(db, make_user, as_user, monkeypatch):
+    _smtp_on(monkeypatch)
+    sent = _capture(monkeypatch, "send_access_approved")
+    admin = make_user(email="admin@example.com", role="admin")
+    inv = Invite(email="ready@example.com", status="pending")
+    db.add(inv)
+    db.commit()
+    make_user(email="ready@example.com", password=_PW, is_active=False)
+
+    _approve(as_user(admin), inv.id)
+
+    (_, _lang, link, has_account, _), _ = sent[0]
+    assert link is None and has_account is True  # no link to offer, and none needed
+
+
+def test_someone_with_no_account_yet_is_told_a_second_mail_is_coming(
+    db, make_user, as_user, monkeypatch
+):
+    _smtp_on(monkeypatch)
+    sent = _capture(monkeypatch, "send_access_approved")
+    admin = make_user(email="admin@example.com", role="admin")
+    inv = Invite(email="stranger@example.com", status="pending")
+    db.add(inv)
+    db.commit()
+
+    _approve(as_user(admin), inv.id)
+
+    (_, _lang, link, has_account, _), _ = sent[0]
+    # Nothing to link to yet. Saying a confirmation mail follows is what makes its ABSENCE
+    # noticeable — the failure that went unnoticed on 2026-09-03.
+    assert link is None and has_account is False
+
+
+# --- the deliberate invitation --------------------------------------------------------------------
+
+
+def test_adding_an_address_to_the_whitelist_mails_nobody(db, make_user, as_user, monkeypatch):
+    _smtp_on(monkeypatch)
+    approved = _capture(monkeypatch, "send_access_approved")
+    invited = _capture(monkeypatch, "send_access_invitation")
+    admin = make_user(email="admin@example.com", role="admin")
+
+    r = as_user(admin).post("/api/admin/invites", json={"email": "maybe@example.com"})
+
+    # Whitelisting opens a door as a possibility — often already agreed in person — and an address
+    # can sit approved for weeks. A mail fired automatically here would be nudging someone who never
+    # asked to be nudged.
+    assert r.status_code == 200 and r.json()["invited_at"] is None
+    assert approved == [] and invited == []
+
+
+def test_the_admin_can_then_invite_them_on_purpose(db, make_user, as_user, monkeypatch):
+    _smtp_on(monkeypatch)
+    invited = _capture(monkeypatch, "send_access_invitation")
+    admin = make_user(email="admin@example.com", role="admin")
+    inv = Invite(email="maybe@example.com", status="approved", decided_by=admin.email)
+    db.add(inv)
+    db.commit()
+
+    r = as_user(admin).post(f"/api/admin/invites/{inv.id}/invite")
+
+    assert r.status_code == 200 and r.json()["invited_at"] is not None
+    assert invited[0][0][0] == "maybe@example.com"
+    # Recorded on the row, so "did I already write to them?" has an answer where the decision is
+    # made — the wrong answer means mailing a real person twice.
+    db.expire_all()
+    assert db.get(Invite, inv.id).invited_at is not None
+    assert "invite_send" in db.execute(select(AuditLog.action)).scalars().all()
+
+
+def test_an_undecided_request_cannot_be_invited(db, make_user, as_user, monkeypatch):
+    _smtp_on(monkeypatch)
+    admin = make_user(email="admin@example.com", role="admin")
+    inv = Invite(email="asking@example.com", status="pending")
+    db.add(inv)
+    db.commit()
+
+    r = as_user(admin).post(f"/api/admin/invites/{inv.id}/invite")
+
+    assert r.status_code == 409 and r.json()["detail"]["reason"] == "not_approved"
+
+
+def test_the_invitation_says_so_when_the_instance_cannot_send_mail(
+    db, make_user, as_user, monkeypatch
+):
+    from app import email as email_mod
+
+    monkeypatch.setattr(email_mod, "email_enabled", lambda db=None: False)
+    admin = make_user(email="admin@example.com", role="admin")
+    inv = Invite(email="maybe@example.com", status="approved", decided_by=admin.email)
+    db.add(inv)
+    db.commit()
+
+    r = as_user(admin).post(f"/api/admin/invites/{inv.id}/invite")
+
+    assert r.status_code == 409 and r.json()["detail"]["reason"] == "email_off"
+    db.expire_all()
+    assert db.get(Invite, inv.id).invited_at is None  # nothing sent, nothing recorded
+
+
+# --- the silent register no-op --------------------------------------------------------------------
+
+
+def test_registering_again_re_sends_the_link_instead_of_sending_nothing(db, client, monkeypatch):
+    _smtp_on(monkeypatch)
+    sent = _capture(monkeypatch, "send_verify_email")
+    assert (
+        client.post(
+            "/auth/register", json={"email": "twice@example.com", "password": _PW}
+        ).status_code
+        == 200
+    )
+    assert len(sent) == 1
+
+    r = client.post("/auth/register", json={"email": "twice@example.com", "password": _PW})
+
+    # The old behaviour was to return in silence: same cheerful "check your inbox", no mail. That is
+    # the most likely explanation for the 2026-09-03 confirmation mail that "never arrived" — none
+    # was ever sent. The response stays uniform; only the dead end is gone.
+    assert r.status_code == 200 and r.json() == {"status": "ok"}
+    assert len(sent) == 2
+    assert sent[1][0][0] == "twice@example.com"
+
+
+def test_registering_again_does_not_create_a_second_account(db, client, monkeypatch):
+    _smtp_on(monkeypatch)
+    _capture(monkeypatch, "send_verify_email")
+    for _ in range(2):
+        client.post("/auth/register", json={"email": "twice@example.com", "password": _PW})
+
+    db.expire_all()
+    rows = db.execute(select(User).where(User.email == "twice@example.com")).scalars().all()
+    assert len(rows) == 1
+
+
+def test_a_confirmed_account_still_gets_nothing(db, client, make_user, monkeypatch):
+    _smtp_on(monkeypatch)
+    sent = _capture(monkeypatch, "send_verify_email")
+    make_user(email="done@example.com", password=_PW)  # already verified
+
+    r = client.post("/auth/register", json={"email": "done@example.com", "password": _PW})
+
+    # There is nothing to confirm, so there is nothing to send — and mailing "confirm your address"
+    # to someone who already did would be a lie.
+    assert r.status_code == 200
+    assert sent == []

frontend/src/App.tsx

@@ -17,6 +17,7 @@ import {
 import { notify, removeByMetaKind } from "./lib/notifications";
 import { LS, setAccountRaw } from "./lib/storage";
 import { usePref } from "./lib/usePref";
+import { useVerifyEntry } from "./lib/useVerifyEntry";
 import { useNavigation, useNavigationActions } from "./components/NavigationProvider";
 import { useFeedFilters, useFeedFiltersActions } from "./components/FeedFiltersProvider";
 import { useChannelLayout } from "./components/ChannelsProvider";
@@ -37,6 +38,7 @@ import { StateMessage } from "./components/QueryState";
 import ErrorDialog from "./components/ErrorDialog";
 import VersionBanner from "./components/VersionBanner";
 import DemoBanner from "./components/DemoBanner";
+import VerifyBanner from "./components/VerifyBanner";
 import { focusAccessRequestsTab } from "./lib/adminUsersTab";
 // The built app version, NOT imported from releaseNotes — importing anything from that module
 // pulls its whole ~900-line changelog into the eager App chunk and defeats the lazy ReleaseNotes
@@ -54,6 +56,11 @@ export default function App() {
   const { t, i18n } = useTranslation();
   const { page, channelView, ytSearch } = useNavigation();
   const { setPage, enterYtSearch } = useNavigationActions();
+  // An emailed verification link is confirmed HERE, above the signed-in/signed-out branch below, so
+  // it works in a browser that already holds a session. It used to be handled inside Welcome, which
+  // that branch never renders when signed in — the token was silently dropped. Signed out, the
+  // outcome goes to the auth card's banners; signed in, to the top-of-app bar.
+  const verifyEntry = useVerifyEntry();
   // The global feed filters live in FeedFiltersProvider (per-account persistence + the account-load
   // effect + share-link capture all moved there). App reads them to hand to <Feed> and to the
   // handlers that mutate the feed view (onShowInFeed, tag-click, the feed scrollKey).
@@ -240,7 +247,10 @@ export default function App() {
     // Keep a single, current nudge: drop any prior one (persisted copies reload as dismissed
     // history, so they'd otherwise pile up one-per-reload) before re-issuing the live notice.
     removeByMetaKind("access-requests");
-    const pending = meQuery.data.pending_invites ?? 0;
+    // Both kinds of "someone is waiting on you": a request needing a decision, and a sign-up whose
+    // address was approved before they registered. The second used to produce NO signal at all —
+    // nothing lands in the queue for it — which is how the 2026-09-03 registrant went unnoticed.
+    const pending = (meQuery.data.pending_invites ?? 0) + (meQuery.data.pending_activations ?? 0);
     if (pending > 0) {
       notify({
         level: "warning",
@@ -259,7 +269,7 @@ export default function App() {
       });
     }
     // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [meQuery.data?.role, meQuery.data?.pending_invites]);
+  }, [meQuery.data?.role, meQuery.data?.pending_invites, meQuery.data?.pending_activations]);
 
   // Language is edited outside the Settings page (sidebar/login), so it stays instant.
   function changeLanguage(code: LangCode) {
@@ -288,7 +298,7 @@ export default function App() {
         </StateMessage>
       </div>
     );
-  if (!meQuery.data) return <Welcome />;
+  if (!meQuery.data) return <Welcome verify={verifyEntry} />;
 
   // Shown briefly while a lazy page/module chunk loads (first visit to that page only).
   const pageFallback = (
@@ -386,6 +396,7 @@ export default function App() {
             header={<Header me={meQuery.data!} onYtSearch={enterYtSearch} />}
             banners={
               <>
+                <VerifyBanner entry={verifyEntry} />
                 {meQuery.data!.is_demo && <DemoBanner />}
                 <VersionBanner onOpen={() => openReleaseNotes(FRONTEND_VERSION)} />
               </>

frontend/src/components/AdminUsers.tsx

@@ -2,12 +2,34 @@ import { useState } from "react";
 import { qk } from "../lib/queryKeys";
 import { useTranslation } from "react-i18next";
 import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
-import { Ban, Check, RotateCcw, Shield, Trash2, UserPlus, X } from "lucide-react";
-import { api, type AdminUserRow, type Invite, type Me } from "../lib/api";
+import {
+  Ban,
+  Check,
+  Clock,
+  MailWarning,
+  Mails,
+  RotateCcw,
+  Send,
+  Shield,
+  Trash2,
+  UserPlus,
+  X,
+} from "lucide-react";
+import {
+  api,
+  HttpError,
+  type AdminUserRow,
+  type Invite,
+  type Me,
+  type PendingAccessRow,
+} from "../lib/api";
 import { notify } from "../lib/notifications";
 import { ADMIN_USERS_TAB_KEY } from "../lib/adminUsersTab";
 import Tooltip from "./Tooltip";
+import InlineNotice from "./InlineNotice";
 import { Section } from "./ui/form";
+import SegmentedToggle from "./SegmentedToggle";
+import { LANGUAGES, type LangCode } from "../i18n";
 import { LoadingState, StateMessage } from "./QueryState";
 import { useConfirm } from "./ConfirmProvider";
 import Tabs, { usePersistedTab } from "./Tabs";
@@ -26,7 +48,14 @@ export default function AdminUsers() {
   const [tab, setTab] = usePersistedTab(ADMIN_USERS_TAB_KEY, "roles");
   const tabs = [
     { id: "roles", label: t("users.tabs.roles") },
-    { id: "access", label: t("users.tabs.access"), badge: me.pending_invites },
+    // Both kinds of "waiting on the admin": a request needing a decision, and a sign-up whose
+    // address was approved BEFORE they registered — the second never reaches the invite queue,
+    // so the badge used to read zero while somebody sat locked out (roadmap UX-25).
+    {
+      id: "access",
+      label: t("users.tabs.access"),
+      badge: me.pending_invites + me.pending_activations,
+    },
     { id: "demo", label: t("users.tabs.demo") },
   ];
   const active = tabs.some((x) => x.id === tab) ? tab : "roles";
@@ -40,7 +69,12 @@ export default function AdminUsers() {
       </PageToolbar>
       <div className="px-4 pb-4 pt-3 max-w-3xl w-full mx-auto">
         {active === "roles" && <UsersRoles me={me} />}
-        {active === "access" && <AdminInvites />}
+        {active === "access" && (
+          <>
+            <AdminInvites />
+            <PendingAccess />
+          </>
+        )}
         {active === "demo" && <AdminDemo />}
       </div>
     </>
@@ -260,17 +294,217 @@ function UsersRoles({ me }: { me: Me }) {
   );
 }
 
+/** Did the invitation fail because this instance has no working SMTP? */
+function inviteEmailOff(err: HttpError): boolean {
+  const d = err.detailData as { code?: string; reason?: string } | null | undefined;
+  return d?.code === "invite_send" && d.reason === "email_off";
+}
+
+// --- Sign-ups that are still outside (roadmap UX-25) --------------------------------------------
+//
+// The gap this closes: approve an address BEFORE the person registers and their sign-up produces no
+// queue row at all — `_decide` only takes a pending invite — so the Access-requests screen above was
+// empty while they sat locked out. The only working move was re-typing the address into the
+// whitelist box, which nobody would guess. This section makes the state visible and the fix one
+// click, WITHOUT changing who may cause what: the button is admin-authenticated and explicit. Two
+// earlier attempts moved authority instead (auto-activating on registration, reopening the approved
+// invite) and were reverted after review.
+function PendingAccess() {
+  const { t } = useTranslation();
+  const qc = useQueryClient();
+  const rows = useQuery({
+    queryKey: qk.adminPendingAccess(),
+    queryFn: () => api.adminPendingAccess(),
+  });
+  // Activating changes /api/me's badge count too, so refresh both or the number lies until reload.
+  const refresh = () => {
+    qc.invalidateQueries({ queryKey: qk.adminPendingAccess() });
+    qc.invalidateQueries({ queryKey: qk.me() });
+    qc.invalidateQueries({ queryKey: qk.adminUsers() });
+  };
+
+  const activate = useMutation({
+    mutationFn: (u: PendingAccessRow) => api.activateUser(u.id),
+    onSuccess: (_r, u) => {
+      refresh();
+      notify({ level: "success", message: t("users.pendingAccess.activated", { email: u.email }) });
+    },
+    onError: () => notify({ level: "error", message: t("users.pendingAccess.activateFailed") }),
+  });
+
+  const resend = useMutation({
+    mutationFn: (u: PendingAccessRow) => api.resendUserVerification(u.id),
+    onSuccess: (_r, u) => {
+      refresh();
+      notify({ level: "success", message: t("users.pendingAccess.resent", { email: u.email }) });
+    },
+    // The public resend is deliberately silent; this one is not, so say WHY it failed — an instance
+    // with no working SMTP would otherwise show a success toast for a mail that was never sent.
+    onError: (err) =>
+      notify({
+        level: "error",
+        message:
+          err instanceof HttpError && isEmailOff(err)
+            ? t("users.pendingAccess.resendEmailOff")
+            : t("users.pendingAccess.resendFailed"),
+      }),
+  });
+
+  const list = rows.data ?? [];
+  const busy = activate.isPending || resend.isPending;
+  if (rows.isSuccess && list.length === 0) return null; // nothing stuck: no empty box to explain
+
+  return (
+    <Section card title={t("users.pendingAccess.title")}>
+      <p className="text-xs text-muted leading-relaxed mb-3">{t("users.pendingAccess.body")}</p>
+      {rows.isError && !rows.data ? (
+        <StateMessage tone="error" onRetry={() => rows.refetch()}>
+          {t("common.loadError")}
+        </StateMessage>
+      ) : rows.isLoading && !rows.data ? (
+        <LoadingState />
+      ) : (
+        <div className="space-y-1.5">
+          {list.map((u) => (
+            <PendingAccessRowView
+              key={u.id}
+              row={u}
+              busy={busy}
+              onActivate={() => activate.mutate(u)}
+              onResend={() => resend.mutate(u)}
+            />
+          ))}
+        </div>
+      )}
+    </Section>
+  );
+}
+
+/** Did the resend fail because this instance has no working SMTP? */
+function isEmailOff(err: HttpError): boolean {
+  const d = err.detailData as { code?: string; reason?: string } | null | undefined;
+  return d?.code === "resend" && d.reason === "email_off";
+}
+
+// One stuck sign-up. The row names WHICH gate is shut rather than just offering buttons — the same
+// reasoning as the sign-in card's blocked panel, from the admin's side: an admin about to let someone
+// in should see that the address has not been confirmed yet, because on a no-SMTP instance that is
+// the difference between the owner and whoever registered the address first (roadmap SEC-15).
+function PendingAccessRowView({
+  row,
+  busy,
+  onActivate,
+  onResend,
+}: {
+  row: PendingAccessRow;
+  busy: boolean;
+  onActivate: () => void;
+  onResend: () => void;
+}) {
+  const { t } = useTranslation();
+  return (
+    <div className="glass-card flex items-center gap-2 p-2.5 rounded-xl">
+      <div className="min-w-0 flex-1">
+        <div className="text-sm truncate">{row.email}</div>
+        <div className="text-2xs text-muted flex items-center gap-2 mt-0.5 flex-wrap">
+          {row.created_at && (
+            <span>
+              {t("users.pendingAccess.signedUp", {
+                time: new Date(row.created_at).toLocaleString(),
+              })}
+            </span>
+          )}
+          {row.email_verified ? (
+            <span className="inline-flex items-center gap-1 text-success">
+              <Check className="w-3 h-3" />
+              {t("users.pendingAccess.emailConfirmed")}
+            </span>
+          ) : (
+            <span className="inline-flex items-center gap-1 text-warn">
+              <MailWarning className="w-3 h-3" />
+              {t("users.pendingAccess.emailUnconfirmed")}
+            </span>
+          )}
+          {!row.is_active && (
+            <span className="inline-flex items-center gap-1">
+              <Clock className="w-3 h-3" />
+              {t("users.pendingAccess.inactive")}
+            </span>
+          )}
+        </div>
+      </div>
+      {!row.email_verified && (
+        <Tooltip hint={t("users.pendingAccess.resendHint")}>
+          <button
+            onClick={onResend}
+            disabled={busy}
+            className="shrink-0 p-1.5 rounded-lg border border-border text-muted hover:text-fg disabled:opacity-50 transition"
+            aria-label={t("users.pendingAccess.resend")}
+          >
+            <Send className="w-4 h-4" />
+          </button>
+        </Tooltip>
+      )}
+      {row.can_activate && (
+        <Tooltip hint={t("users.pendingAccess.activateHint")}>
+          <button
+            onClick={onActivate}
+            disabled={busy}
+            className="shrink-0 px-2.5 py-1.5 rounded-lg border border-accent/40 text-accent text-xs font-medium hover:bg-accent/10 disabled:opacity-50 transition"
+          >
+            {t("users.pendingAccess.activate")}
+          </button>
+        </Tooltip>
+      )}
+    </div>
+  );
+}
+
+/** The mail language for one invitation. Owns its own display state and reports every change up
+ *  through `onPick`, because the dialog that hosts it resolves to a plain boolean — the choice has
+ *  to live in the caller's closure, not in this component. Endonyms come from the app's own
+ *  language list, so a third locale would appear here for free. */
+function InviteLangPicker({
+  initial,
+  onPick,
+}: {
+  initial: LangCode;
+  onPick: (lang: LangCode) => void;
+}) {
+  const { t } = useTranslation();
+  const [lang, setLang] = useState<LangCode>(initial);
+  return (
+    <SegmentedToggle
+      className="mt-3"
+      size="md"
+      ariaLabel={t("settings.invites.inviteLang")}
+      label={t("settings.invites.inviteLang")}
+      options={LANGUAGES.map((l) => ({ value: l.code, label: l.label }))}
+      value={lang}
+      onChange={(v) => {
+        setLang(v);
+        onPick(v);
+      }}
+    />
+  );
+}
+
 // --- Access requests (the Invite whitelist) — moved verbatim from Settings → Account -------
 
 function AdminInvites() {
-  const { t } = useTranslation();
+  const { t, i18n } = useTranslation();
   const qc = useQueryClient();
   const confirm = useConfirm();
+  const me = useMe();
   const invites = useQuery({ queryKey: qk.adminInvites(), queryFn: () => api.adminInvites() });
   const [newEmail, setNewEmail] = useState("");
   const refresh = () => {
     qc.invalidateQueries({ queryKey: qk.adminInvites() });
     qc.invalidateQueries({ queryKey: qk.me() }); // updates the pending badge
+    // The stuck-sign-ups section below describes the same backlog and changes with every decision
+    // here: approving an address moves a registrant INTO it (active, still unverified), whitelisting
+    // one takes a row out. Leaving it stale hides the resend button this epic added for them.
+    qc.invalidateQueries({ queryKey: qk.adminPendingAccess() });
   };
   const approve = useMutation({
     mutationFn: ({ id }: { id: number; email: string }) => api.approveInvite(id),
@@ -297,6 +531,92 @@ function AdminInvites() {
     });
     if (ok) deny.mutate(i.id);
   };
+  const remove = useMutation({
+    mutationFn: (id: number) => api.deleteInvite(id),
+    onSuccess: (d) => {
+      refresh();
+      // Removing the row is not always a revoke: is_allowed falls back to the env allow-lists, so
+      // for an address on those the person keeps access. Saying "removed" alone would mislead.
+      if (d.still_allowed_by_env)
+        notify({ level: "warning", message: t("settings.invites.deletedStillAllowed") });
+      else notify({ level: "success", message: t("settings.invites.deleted") });
+    },
+    onError: (e) => {
+      // A 409 means the list was stale — someone registered on that address since it loaded. Say
+      // what to do instead of a generic failure, and refetch so the row re-renders as read-only.
+      const conflict = e instanceof HttpError && e.status === 409;
+      notify({
+        level: "error",
+        message: t(
+          conflict ? "settings.invites.deleteHasAccount" : "settings.invites.deleteFailed",
+        ),
+      });
+      if (conflict) refresh();
+    },
+  });
+  const onDelete = async (i: Invite) => {
+    const ok = await confirm({
+      title: t("settings.invites.deleteTitle"),
+      // Removing the row is not a revoke when the address is also in the server's env allow-lists —
+      // say so while the admin can still change their mind, not in a toast after the fact.
+      message: t(
+        i.still_allowed_by_env
+          ? "settings.invites.deleteConfirmStillAllowed"
+          : "settings.invites.deleteConfirm",
+        { email: i.email },
+      ),
+      confirmLabel: t("settings.invites.delete"),
+      danger: true,
+    });
+    if (ok) remove.mutate(i.id);
+  };
+  // Sending is its OWN act, never a side effect of approving an address: the operator opens a door
+  // as a possibility (often already agreed in person), and a mail fired automatically would be
+  // nudging someone who never asked. `invited_at` comes back on the row so a second click is a
+  // decision rather than an accident.
+  const invite = useMutation({
+    mutationFn: (v: { inv: Invite; lang: LangCode }) => api.sendInvitation(v.inv.id, v.lang),
+    onSuccess: (_r, v) => {
+      refresh();
+      notify({ level: "success", message: t("settings.invites.invited", { email: v.inv.email }) });
+    },
+    onError: (err) =>
+      notify({
+        level: "error",
+        message:
+          err instanceof HttpError && inviteEmailOff(err)
+            ? t("settings.invites.inviteEmailOff")
+            : t("settings.invites.inviteFailed"),
+      }),
+  });
+  // The one recipient the app has no language signal about: the admin typed this address in, so
+  // nobody ever told us how to write to its owner. The dialog is where that gets decided — and it
+  // is also where the "you already wrote to them" warning belongs, next to the button that would
+  // do it a second time, rather than only in a tooltip the admin may never hover.
+  const onInvite = async (inv: Invite) => {
+    let lang: LangCode = LANGUAGES.some((l) => l.code === inv.lang)
+      ? (inv.lang as LangCode)
+      : ((i18n.language.split("-")[0] === "hu" ? "hu" : "en") as LangCode);
+    const ok = await confirm({
+      title: t("settings.invites.inviteTitle"),
+      message: (
+        <>
+          <p>
+            {t(
+              inv.invited_at
+                ? "settings.invites.inviteConfirmAgain"
+                : "settings.invites.inviteConfirm",
+              { email: inv.email, time: new Date(inv.invited_at ?? 0).toLocaleString() },
+            )}
+          </p>
+          <InviteLangPicker initial={lang} onPick={(v) => (lang = v)} />
+        </>
+      ),
+      confirmLabel: t("settings.invites.inviteSend"),
+    });
+    if (ok) invite.mutate({ inv, lang });
+  };
+
   const add = useMutation({
     mutationFn: (email: string) => api.addInvite(email),
     onSuccess: (_d, email) => {
@@ -313,6 +633,9 @@ function AdminInvites() {
 
   return (
     <Section card title={t("settings.invites.title")}>
+      {!me.email_configured && (
+        <InlineNotice className="mb-3">{t("settings.invites.emailOff")}</InlineNotice>
+      )}
       {invites.isError && !invites.data ? (
         <StateMessage tone="error" onRetry={() => invites.refetch()}>
           {t("common.loadError")}
@@ -329,7 +652,8 @@ function AdminInvites() {
               inv={i}
               onApprove={() => approve.mutate({ id: i.id, email: i.email })}
               onDeny={() => onDeny(i)}
-              busy={approve.isPending || deny.isPending}
+              onDelete={() => onDelete(i)}
+              busy={approve.isPending || deny.isPending || remove.isPending}
             />
           ))}
         </div>
@@ -364,11 +688,67 @@ function AdminInvites() {
           </summary>
           <div className="mt-2 space-y-1 text-xs text-muted">
             {decided.map((i) => (
-              <div key={i.id} className="flex items-center justify-between gap-2">
-                <span className="truncate">{i.email}</span>
+              <div key={i.id} className="flex items-center gap-2">
+                <span className="truncate flex-1">{i.email}</span>
                 <span className={i.status === "approved" ? "text-accent" : "text-danger"}>
                   {i.status}
                 </span>
+                {/* Only an approved row with NOBODY behind it yet: this button means "the door is
+                    open, come in", which is meaningless to someone already inside — and half the
+                    whitelist is existing users. An account that exists but is still stuck has its
+                    own surface above, with a re-send. The label carries the answer to "did I already
+                    write to them?", the question whose wrong answer means mailing a person twice. */}
+                {i.status === "approved" && !i.has_account && (
+                  <Tooltip
+                    hint={
+                      i.invited_at
+                        ? t("settings.invites.invitedAt", {
+                            time: new Date(i.invited_at).toLocaleString(),
+                          })
+                        : t("settings.invites.inviteHint")
+                    }
+                  >
+                    <button
+                      onClick={() => onInvite(i)}
+                      disabled={invite.isPending}
+                      className={`shrink-0 p-1 rounded-md disabled:opacity-50 transition ${
+                        i.invited_at
+                          ? "text-muted/50 hover:text-fg"
+                          : "text-muted hover:text-accent"
+                      }`}
+                      aria-label={t("settings.invites.inviteLabel", { email: i.email })}
+                    >
+                      <Mails className="w-3.5 h-3.5" />
+                    </button>
+                  </Tooltip>
+                )}
+                {/* An entry with an account behind it stays read-only: deleting it would revoke that
+                    user's access, since is_allowed reads this row. Delete the user instead. */}
+                {i.has_account ? (
+                  // `disabled` would drop it from the tab order AND suppress the title, so the
+                  // reason reached nobody — same call as the Playlists drag handle.
+                  <button
+                    type="button"
+                    aria-disabled
+                    onClick={(e) => e.preventDefault()}
+                    title={t("settings.invites.deleteHasAccount")}
+                    aria-label={t("settings.invites.deleteHasAccount")}
+                    className="shrink-0 p-1 text-muted/50 cursor-not-allowed"
+                  >
+                    <Trash2 className="w-3.5 h-3.5" />
+                  </button>
+                ) : (
+                  <Tooltip hint={t("settings.invites.deleteHint")}>
+                    <button
+                      onClick={() => onDelete(i)}
+                      disabled={remove.isPending}
+                      className="shrink-0 p-1 rounded-md text-muted hover:text-danger disabled:opacity-50 transition"
+                      aria-label={t("settings.invites.deleteLabel", { email: i.email })}
+                    >
+                      <Trash2 className="w-3.5 h-3.5" />
+                    </button>
+                  </Tooltip>
+                )}
               </div>
             ))}
           </div>
@@ -506,11 +886,13 @@ function InviteRow({
   inv,
   onApprove,
   onDeny,
+  onDelete,
   busy,
 }: {
   inv: Invite;
   onApprove: () => void;
   onDeny: () => void;
+  onDelete: () => void;
   busy: boolean;
 }) {
   const { t } = useTranslation();
@@ -546,6 +928,34 @@ function InviteRow({
           <X className="w-4 h-4" />
         </button>
       </Tooltip>
+      {/* Deny records a decision and keeps the row; delete forgets the address. Once an account
+          exists for it the row is that account's approval gate, so it is managed from Users & roles
+          instead — shown as a disabled control rather than omitted, or the admin sees a row that is
+          silently missing a button their other rows have. */}
+      {inv.has_account ? (
+        // aria-disabled, not `disabled`: the reason has to stay reachable by keyboard.
+        <button
+          type="button"
+          aria-disabled
+          onClick={(e) => e.preventDefault()}
+          title={t("settings.invites.deleteHasAccount")}
+          aria-label={t("settings.invites.deleteHasAccount")}
+          className="shrink-0 p-1.5 rounded-lg border border-border/50 text-muted/50 cursor-not-allowed"
+        >
+          <Trash2 className="w-4 h-4" />
+        </button>
+      ) : (
+        <Tooltip hint={t("settings.invites.deleteHint")}>
+          <button
+            onClick={onDelete}
+            disabled={busy}
+            className="shrink-0 p-1.5 rounded-lg border border-border text-muted hover:text-danger disabled:opacity-50 transition"
+            aria-label={t("settings.invites.deleteLabel", { email: inv.email })}
+          >
+            <Trash2 className="w-4 h-4" />
+          </button>
+        </Tooltip>
+      )}
     </div>
   );
 }

frontend/src/components/Banner.tsx

@@ -26,6 +26,7 @@ export default function Banner({
   action,
   onDismiss,
   dismissTitle,
+  role,
 }: {
   tone: BannerTone;
   icon: LucideIcon;
@@ -33,10 +34,17 @@ export default function Banner({
   action?: { label: string; onClick: () => void };
   onDismiss?: () => void;
   dismissTitle?: string;
+  /** `"status"` for a bar that APPEARS in response to something the user just did, so a screen
+   * reader announces it. Left unset for the permanent bars (demo, version): those are part of the
+   * page when it loads, and announcing them on every visit is noise, not information. */
+  role?: "status";
 }) {
   const c = TONES[tone];
   return (
-    <div className={`shrink-0 flex items-center gap-2 px-4 py-2 text-sm border-b text-fg ${c.bar}`}>
+    <div
+      role={role}
+      className={`shrink-0 flex items-center gap-2 px-4 py-2 text-sm border-b text-fg ${c.bar}`}
+    >
       <Icon className={`w-4 h-4 shrink-0 ${c.icon}`} />
       <span className="min-w-0">{children}</span>
       {action && (

frontend/src/components/ChannelPage.tsx

@@ -12,6 +12,8 @@ import {
   Ban,
   Check,
   ExternalLink,
+  Eye,
+  EyeOff,
   History,
   Loader2,
   Plus,
@@ -32,6 +34,7 @@ import type { FeedView } from "../lib/feedView";
 import { channelYouTubeUrl, formatViews } from "../lib/format";
 import { ChannelTagsControl } from "./ChannelTags";
 import { useChannelTagActions } from "../lib/useChannelTagActions";
+import { Button } from "./ui/Button";
 
 // A dedicated channel page: an "About"-style header (banner, avatar, stats, subscribe) over the
 // channel's videos (the catalog filtered to this channel). For an un-subscribed channel it
@@ -137,6 +140,17 @@ export default function ChannelPage({
     // a caller toast here would just double it.
   });
 
+  // "Hide from feed": the same per-subscription flag the manager toggles (updateChannel {hidden}).
+  // Local DB op — keeps the subscription, only drops the channel's videos from the feed/explore.
+  const toggleHidden = useMutation({
+    mutationFn: () => api.updateChannel(channelId, { hidden: !ch?.hidden }),
+    onSuccess: () => {
+      qc.invalidateQueries({ queryKey: qk.channel(channelId) });
+      qc.invalidateQueries({ queryKey: qk.feed() });
+      qc.invalidateQueries({ queryKey: qk.channels() });
+    },
+  });
+
   const subscribe = useMutation({
     mutationFn: () => api.subscribeChannel(channelId),
     onSuccess: () => {
@@ -418,6 +432,7 @@ export default function ChannelPage({
                     priority={ch.priority}
                     onPriority={(d) => bumpPriority(channelId, d)}
                     onSet={(v) => setPriority(channelId, v)}
+                    size="md"
                   />
                 </div>
               )}
@@ -427,21 +442,18 @@ export default function ChannelPage({
                 it) so a large channel's paced tail reads as visible progress rather than a stuck
                 spinner. */}
               {ch?.subscribed && !ch.backfill_done && !me.is_demo && (
-                <button
+                <Button
+                  variant="outline"
                   onClick={() => !ch.deep_requested && deepBackfill.mutate()}
                   disabled={ch.deep_requested || deepBackfill.isPending}
+                  loading={ch.deep_requested}
+                  icon={<History className="w-4 h-4" />}
                   title={
                     ch.deep_requested
                       ? t("channel.fullHistoryLoadingHint")
                       : t("channel.fullHistory")
                   }
-                  className="inline-flex items-center gap-1.5 px-3 py-2 rounded-lg text-sm border border-border text-muted hover:text-accent hover:border-accent disabled:opacity-60 disabled:hover:text-muted disabled:hover:border-border transition"
                 >
-                  {ch.deep_requested ? (
-                    <Loader2 className="w-4 h-4 animate-spin" />
-                  ) : (
-                    <History className="w-4 h-4" />
-                  )}
                   <span className="hidden sm:inline whitespace-nowrap">
                     {!ch.deep_requested
                       ? t("channel.fullHistory")
@@ -452,7 +464,7 @@ export default function ChannelPage({
                           })
                         : t("channel.fullHistoryLoading")}
                   </span>
-                </button>
+                </Button>
               )}
               {!me.is_demo && (
                 <button
@@ -469,27 +481,45 @@ export default function ChannelPage({
                   <Ban className="w-4 h-4" />
                 </button>
               )}
+              {/* Hide-from-feed toggle — subscription-scoped, so offered only on a followed channel
+                  (mirrors the manager's Eye/EyeOff). Keeps the subscription; only drops its videos
+                  from the feed. EyeOff = currently hidden (click to unhide). */}
+              {ch?.subscribed && !me.is_demo && (
+                <button
+                  onClick={() => toggleHidden.mutate()}
+                  disabled={toggleHidden.isPending}
+                  title={ch.hidden ? t("channel.hiddenHint") : t("channel.hideHint")}
+                  aria-label={ch.hidden ? t("channel.unhide") : t("channel.hide")}
+                  className={`inline-flex items-center justify-center w-9 h-9 rounded-lg border disabled:opacity-50 transition ${
+                    ch.hidden
+                      ? "border-accent text-accent"
+                      : "border-border text-muted hover:text-fg hover:border-fg/40"
+                  }`}
+                >
+                  {ch.hidden ? <EyeOff className="w-4 h-4" /> : <Eye className="w-4 h-4" />}
+                </button>
+              )}
               {!me.is_demo &&
                 !ch?.blocked &&
                 (ch?.subscribed ? (
-                  <button
+                  <Button
+                    variant="outline"
                     onClick={onUnsubscribe}
                     disabled={unsubscribe.isPending}
                     title={t("channel.unsubscribe")}
-                    className="inline-flex items-center gap-1.5 px-3 py-2 rounded-lg text-sm border border-border text-muted hover:text-fg disabled:opacity-50"
+                    icon={<Check className="w-4 h-4" />}
                   >
-                    <Check className="w-4 h-4" />
                     {t("channel.subscribedState")}
-                  </button>
+                  </Button>
                 ) : (
-                  <button
+                  <Button
+                    variant="outline"
                     onClick={() => subscribe.mutate()}
                     disabled={subscribe.isPending}
-                    className="inline-flex items-center gap-1.5 px-3 py-2 rounded-lg text-sm btn-primary disabled:opacity-50"
+                    icon={<Plus className="w-4 h-4" />}
                   >
-                    <Plus className="w-4 h-4" />
                     {t("channel.subscribe")}
-                  </button>
+                  </Button>
                 ))}
               {/* Tagging is a subscription-scoped action (attach_tag → _user_subscription 404s
                   otherwise), and personal tags are for your subscriptions — so only offer it on a

frontend/src/components/ChannelTags.suggest.dom.test.tsx

@@ -0,0 +1,105 @@
+// @vitest-environment jsdom
+//
+// Contract of the suggested-tag ghost chips (E8·S4): on an UNTAGGED channel, ChannelTagsControl renders
+// one dashed "ghost" chip per suggestion; clicking the chip body accepts it (onAcceptSuggestion with the
+// tag id), the trailing × dismisses it (onDismissSuggestion), and a suggestion whose tag is already
+// attached is never shown. i18n is key-passthrough; the control rides the floating-ui popover platform
+// and a ResizeObserver-driven fit measurer, so we stub the observer and wrap in a FloatingTree.
+import { describe, it, expect, afterEach, beforeAll, vi } from "vitest";
+import { render, screen, fireEvent, cleanup } from "@testing-library/react";
+import { FloatingTree } from "@floating-ui/react";
+
+vi.mock("react-i18next", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("react-i18next")>();
+  // Interpolate the `name` option so per-tag accept labels are distinguishable ("…acceptSuggestion:docu").
+  return {
+    ...actual,
+    useTranslation: () => ({
+      t: (key: string, opts?: { name?: string }) => (opts?.name ? `${key}:${opts.name}` : key),
+      i18n: { language: "en" },
+    }),
+  };
+});
+
+import { ChannelTagsControl, type SuggestedTag } from "./ChannelTags";
+import type { Tag } from "../lib/api";
+
+beforeAll(() => {
+  class Stub {
+    observe() {}
+    unobserve() {}
+    disconnect() {}
+    takeRecords() {
+      return [];
+    }
+  }
+  globalThis.ResizeObserver ??= Stub as unknown as typeof ResizeObserver;
+});
+
+afterEach(cleanup);
+
+const tag = (id: number, name: string): Tag => ({
+  id,
+  name,
+  color: null,
+  category: "other",
+  system: false,
+  channel_count: 0,
+});
+const docu = tag(1, "docu");
+const history = tag(2, "history");
+const suggestions: SuggestedTag[] = [
+  { tag: docu, confidence: 0.95 },
+  { tag: history, confidence: 0.6 },
+];
+
+function renderControl(props: Partial<Parameters<typeof ChannelTagsControl>[0]> = {}) {
+  const onAccept = vi.fn();
+  const onDismiss = vi.fn();
+  render(
+    <FloatingTree>
+      <ChannelTagsControl
+        userTags={[docu, history]}
+        attachedIds={[]}
+        onToggle={() => {}}
+        onCreate={() => {}}
+        suggestions={suggestions}
+        onAcceptSuggestion={onAccept}
+        onDismissSuggestion={onDismiss}
+        {...props}
+      />
+    </FloatingTree>,
+  );
+  return { onAccept, onDismiss };
+}
+
+describe("ChannelTagsControl suggested ghost chips", () => {
+  it("renders a ghost chip per suggestion and accepts on click", () => {
+    const { onAccept } = renderControl();
+    // Role query excludes the aria-hidden fit-measurer copy; the name carries the interpolated tag.
+    fireEvent.click(screen.getByRole("button", { name: "channels.tags.acceptSuggestion:docu" }));
+    expect(onAccept).toHaveBeenCalledWith(docu.id);
+  });
+
+  it("dismisses via the × without accepting", () => {
+    const { onAccept, onDismiss } = renderControl();
+    const dismissButtons = screen.getAllByRole("button", {
+      name: "channels.tags.dismissSuggestion",
+    });
+    // Two visible ghost chips (the measurer's copies are aria-hidden → excluded); order matches the
+    // suggestions array, so the second × is the "history" suggestion.
+    expect(dismissButtons).toHaveLength(2);
+    fireEvent.click(dismissButtons[1]!);
+    expect(onDismiss).toHaveBeenCalledWith(history.id);
+    expect(onAccept).not.toHaveBeenCalled();
+  });
+
+  it("shows the attached lane (no ghost chips) once the channel carries a user tag", () => {
+    renderControl({ attachedIds: [docu.id] });
+    // A tagged channel is not "untagged" → the ghost lane is not rendered at all (the server excludes
+    // tagged channels from suggestions; the control mirrors that with its attached-XOR-ghost branch).
+    expect(
+      screen.queryAllByRole("button", { name: "channels.tags.dismissSuggestion" }),
+    ).toHaveLength(0);
+  });
+});

frontend/src/components/ChannelTags.tsx

@@ -1,5 +1,5 @@
 import { useEffect, useRef, useState } from "react";
-import { Check, Plus } from "lucide-react";
+import { Check, Plus, Sparkles, X } from "lucide-react";
 import { useTranslation } from "react-i18next";
 import { type Tag } from "../lib/api";
 import { useAnchoredPopover, PopoverSurface, PopoverItem } from "./AnchoredPopover";
@@ -9,8 +9,8 @@ import { useChipOverflowFit } from "../lib/useChipOverflowFit";
 
 // The channel tag surface, shared by the channel manager (table + cards) and the channel detail
 // page. Built on the R8 popover platform. Two design goals it fixes over the old inline TagsCell:
-//   1. Stable edit anchor — the "+" edit trigger sits in a FIXED slot at the end, so toggling tags
-//      (which grows the chip row) never moves it, and the editor popover doesn't drift.
+//   1. Stable edit anchor — the "+" edit trigger LEADS the row (fixed left slot), so toggling tags
+//      (which grows the chip row to its right) never moves it, and the editor popover doesn't drift.
 //   2. Fixed footprint — the chip row lives in a width-bounded, single-line, overflow-hidden box and
 //      collapses the excess into a "+N" pill (hover reveals the full set). The cell therefore never
 //      wraps to a 2nd line, so it can't widen its table column and reflow every other row.
@@ -40,6 +40,157 @@ function TagChip({ tag, onClick, title }: TagChipProps) {
   );
 }
 
+// A suggested user tag (E8·S4): a dashed "ghost" chip the user hasn't applied yet, learned from
+// their own tagging pattern. The chip body accepts it (one tap → attaches the real tag); the trailing
+// × dismisses it for the session. Rendered only on untagged channels, so it never competes with the
+// measured attached-chip row. (Two sibling buttons, not a button-in-button — invalid nesting.)
+export interface SuggestedTag {
+  tag: Tag;
+  confidence: number;
+}
+
+function SuggestedChip({
+  suggestion,
+  onAccept,
+  onDismiss,
+}: {
+  suggestion: SuggestedTag;
+  onAccept: () => void;
+  onDismiss: () => void;
+}) {
+  const { t } = useTranslation();
+  const pct = Math.round(suggestion.confidence * 100);
+  return (
+    <span className="shrink-0 inline-flex items-center rounded-full border border-dashed border-accent/50 text-accent/90 text-2xs font-medium pl-1 pr-0.5 py-0.5 max-w-36">
+      <button
+        type="button"
+        onClick={onAccept}
+        title={t("channels.tags.suggestedHint", { pct })}
+        aria-label={t("channels.tags.acceptSuggestion", { name: suggestion.tag.name })}
+        className="inline-flex items-center gap-1 min-w-0 hover:text-accent transition"
+      >
+        <Sparkles className="w-2.5 h-2.5 shrink-0" />
+        <span className="truncate">{suggestion.tag.name}</span>
+      </button>
+      <button
+        type="button"
+        onClick={onDismiss}
+        title={t("channels.tags.dismissSuggestion")}
+        aria-label={t("channels.tags.dismissSuggestion")}
+        className="shrink-0 ml-0.5 rounded-full text-accent/60 hover:text-danger transition"
+      >
+        <X className="w-2.5 h-2.5" />
+      </button>
+    </span>
+  );
+}
+
+const GHOST_PILL =
+  "shrink-0 text-3xs px-1.5 py-0.5 rounded-full border border-dashed border-accent/50 text-accent/90";
+
+/** A single-line lane of suggested ghost chips that collapses its overflow into a "+N" pill (hover
+ *  reveals the rest, still accept/dismiss-able), reusing the SAME fit machinery as the attached-chip
+ *  lane. Rendered in the untagged-channel case only, so it owns the full tags-cell width — this is what
+ *  stops a 2nd suggestion from being clipped mid-word right next to the edit "+". */
+function SuggestedChipsLane({
+  suggestions,
+  onAccept,
+  onDismiss,
+}: {
+  suggestions: SuggestedTag[];
+  onAccept: (tagId: number) => void;
+  onDismiss: (tagId: number) => void;
+}) {
+  const { t } = useTranslation();
+  const rowRef = useRef<HTMLDivElement | null>(null);
+  const chipRefs = useRef<Array<HTMLElement | null>>([]);
+  const pillRef = useRef<HTMLSpanElement | null>(null);
+  const key = suggestions.map((s) => `${s.tag.id}:${s.tag.name}`).join("|");
+  const visible = useChipOverflowFit<number>({
+    rowRef,
+    chipsRef: chipRefs,
+    pillRef,
+    deps: key,
+    initial: suggestions.length,
+    decide: (g) =>
+      fitChipsWithPill({ chipRights: g.chipRights, pillW: g.pillW, avail: g.avail, gap: g.gap }),
+  });
+  const hidden = suggestions.length - visible;
+
+  const [overflowOpen, setOverflowOpen] = useState(false);
+  const overflowPop = useAnchoredPopover({
+    open: overflowOpen,
+    onOpenChange: setOverflowOpen,
+    mode: "hover",
+    placement: "bottom",
+  });
+  useEffect(() => {
+    if (hidden === 0 && overflowOpen) setOverflowOpen(false);
+  }, [hidden, overflowOpen]);
+
+  return (
+    <div className="relative flex items-center gap-1 min-w-0 flex-1">
+      {/* Hidden measurer — real ghost chips at natural width so the fit hook reads their right edges. */}
+      <div
+        aria-hidden
+        className="pointer-events-none invisible absolute left-0 top-0 flex items-center gap-1 whitespace-nowrap"
+      >
+        {suggestions.map((s, i) => (
+          <span
+            key={s.tag.id}
+            ref={(el) => {
+              chipRefs.current[i] = el;
+            }}
+            className="inline-flex"
+          >
+            <SuggestedChip suggestion={s} onAccept={() => {}} onDismiss={() => {}} />
+          </span>
+        ))}
+        <span ref={pillRef} className={GHOST_PILL}>
+          +{suggestions.length}
+        </span>
+      </div>
+
+      <div ref={rowRef} className="flex items-center gap-1 min-w-0 flex-1 overflow-hidden">
+        {suggestions.slice(0, visible).map((s) => (
+          <SuggestedChip
+            key={s.tag.id}
+            suggestion={s}
+            onAccept={() => onAccept(s.tag.id)}
+            onDismiss={() => onDismiss(s.tag.id)}
+          />
+        ))}
+        {hidden > 0 && (
+          <button
+            ref={overflowPop.refs.setReference}
+            type="button"
+            aria-label={t("channels.tags.moreCount", { count: hidden })}
+            className={`${GHOST_PILL} hover:text-accent transition`}
+            {...overflowPop.getReferenceProps()}
+          >
+            +{hidden}
+          </button>
+        )}
+      </div>
+
+      {/* Hover: the overflowed suggestions, each still one-tap accept / × dismiss. */}
+      <PopoverSurface
+        popover={overflowPop}
+        className="glass-menu max-w-[18rem] rounded-xl p-1.5 flex flex-wrap items-center gap-1 animate-[popIn_0.16s_ease]"
+      >
+        {suggestions.slice(visible).map((s) => (
+          <SuggestedChip
+            key={s.tag.id}
+            suggestion={s}
+            onAccept={() => onAccept(s.tag.id)}
+            onDismiss={() => onDismiss(s.tag.id)}
+          />
+        ))}
+      </PopoverSurface>
+    </div>
+  );
+}
+
 /** The editor body: toggle the user's existing tags on/off for this channel, plus an inline
  *  "create + attach" input. Rendered inside an anchored `menu` popover. (Exported for the channel
  *  detail page in Part 2; internal for now.) */
@@ -130,15 +281,18 @@ function TagEditorMenu({
   );
 }
 
-/** The full tag control for a channel: a width-bounded chip row with "+N" overflow (hover reveals
- *  all), followed by a stable "+" trigger that opens the shared editor. Fills its container width,
- *  so a table cell bounds it via the column width and a card bounds it via the card. */
+/** The full tag control for a channel: a stable leading "+" trigger (opens the shared editor),
+ *  followed by a width-bounded chip row with "+N" overflow (hover reveals all). Fills its container
+ *  width, so a table cell bounds it via the column width and a card bounds it via the card. */
 export function ChannelTagsControl({
   userTags,
   attachedIds,
   onToggle,
   onCreate,
   onChipClick,
+  suggestions,
+  onAcceptSuggestion,
+  onDismissSuggestion,
   bounded = true,
 }: {
   userTags: Tag[];
@@ -147,6 +301,11 @@ export function ChannelTagsControl({
   onCreate: (name: string) => void;
   /** Manager only: clicking a chip filters the feed by that tag. Omit on the detail page. */
   onChipClick?: (tagId: number, name: string) => void;
+  /** Manager only (E8·S4): suggested user tags for an UNTAGGED channel, shown as accept/dismiss ghost
+   *  chips after the (empty) attached row. Omit on the detail page. */
+  suggestions?: SuggestedTag[];
+  onAcceptSuggestion?: (tagId: number) => void;
+  onDismissSuggestion?: (tagId: number) => void;
   /** Cap the chip row at a fixed 12rem so it can't widen a `table-layout:auto` column and reflow the
    *  table (the manager). Set false where there is free width (the channel detail header), so tags
    *  fit inline instead of needlessly collapsing into "+N". */
@@ -154,6 +313,9 @@ export function ChannelTagsControl({
 }) {
   const { t } = useTranslation();
   const attached = userTags.filter((tg) => attachedIds.includes(tg.id));
+  // Suggestions only surface for channels with no user tag yet, but guard anyway: never suggest a tag
+  // the channel already carries (an optimistic accept adds it before the query refetches).
+  const shownSuggestions = (suggestions ?? []).filter((s) => !attachedIds.includes(s.tag.id));
 
   // Deterministic single-line fit: a hidden measurer lays out ALL chips + a sample "+N" pill at their
   // natural widths; the shared measure core (useChipOverflowFit) reads each chip's right edge, the rem
@@ -214,61 +376,86 @@ export function ChannelTagsControl({
     <div
       className={`relative flex items-center gap-1 min-w-0 ${bounded ? "w-48 max-w-full" : "w-full"}`}
     >
-      {/* Hidden measurer: all chips + a sample pill, laid out unbounded to read their true widths. Each
-          chip is wrapped in a ref span (index-aligned) so the shared fit hook can read its right edge;
-          the pill is the sample the hook reserves room for. */}
-      <div
-        aria-hidden
-        className="pointer-events-none invisible absolute left-0 top-0 flex items-center gap-1 whitespace-nowrap"
-      >
-        {attached.map((tg, i) => (
-          <span
-            key={tg.id}
-            ref={(el) => {
-              chipRefs.current[i] = el;
-            }}
-            className="inline-flex"
-          >
-            <TagChip tag={tg} />
-          </span>
-        ))}
-        <span ref={pillRef} className={pillClass}>
-          +{attached.length}
-        </span>
-      </div>
-
-      <div ref={rowRef} className="flex items-center gap-1 min-w-0 flex-1 overflow-hidden">
-        {attached.slice(0, visible).map((tg) => (
-          <TagChip
-            key={tg.id}
-            tag={tg}
-            onClick={onChipClick ? () => onChipClick(tg.id, tg.name) : undefined}
-            title={onChipClick ? t("channels.row.filterFeedByTag", { name: tg.name }) : undefined}
-          />
-        ))}
-        {hidden > 0 && (
-          <button
-            ref={overflowPop.refs.setReference}
-            type="button"
-            className={`${pillClass} hover:text-fg transition`}
-            {...overflowPop.getReferenceProps()}
-          >
-            +{hidden}
-          </button>
-        )}
-      </div>
-
+      {/* The add trigger LEADS the row — a stable left anchor that never moves as chips are added
+          (they grow to its right), so its editor popover can't drift. Compact icon in the width-
+          bounded manager cell; a labelled "＋ Tag" pill where there's free width (the detail header). */}
       <button
         ref={editPop.refs.setReference}
         type="button"
         title={t("channels.row.editTags")}
         aria-label={t("channels.row.editTags")}
-        className="shrink-0 w-5 h-5 inline-flex items-center justify-center rounded-full border border-dashed border-border text-muted hover:text-accent hover:border-accent transition"
+        className={
+          bounded
+            ? "shrink-0 w-5 h-5 inline-flex items-center justify-center rounded-full border border-dashed border-border text-muted hover:text-accent hover:border-accent transition"
+            : "shrink-0 inline-flex items-center gap-1 h-6 pl-1.5 pr-2 rounded-full border border-dashed border-border text-2xs font-medium text-muted hover:text-accent hover:border-accent transition"
+        }
         {...editPop.getReferenceProps()}
       >
-        <Plus className="w-3 h-3" />
+        <Plus className="w-3 h-3 shrink-0" />
+        {!bounded && <span className="whitespace-nowrap">{t("channels.tags.add")}</span>}
       </button>
 
+      {/* Untagged + has suggestions → the ghost-chip lane (its own overflow "+N"); otherwise the
+          attached-chip lane. The two are mutually exclusive: suggestions are computed for untagged
+          channels only, and accepting one removes the channel from the suggestion set — so a channel
+          never shows both, and each lane gets the full cell width instead of clipping the other. */}
+      {attached.length === 0 && shownSuggestions.length > 0 ? (
+        <SuggestedChipsLane
+          suggestions={shownSuggestions}
+          onAccept={(tagId) => onAcceptSuggestion?.(tagId)}
+          onDismiss={(tagId) => onDismissSuggestion?.(tagId)}
+        />
+      ) : (
+        <>
+          {/* Hidden measurer: all chips + a sample pill, laid out unbounded to read their true widths.
+              Each chip is wrapped in a ref span (index-aligned) so the shared fit hook can read its
+              right edge; the pill is the sample the hook reserves room for. */}
+          <div
+            aria-hidden
+            className="pointer-events-none invisible absolute left-0 top-0 flex items-center gap-1 whitespace-nowrap"
+          >
+            {attached.map((tg, i) => (
+              <span
+                key={tg.id}
+                ref={(el) => {
+                  chipRefs.current[i] = el;
+                }}
+                className="inline-flex"
+              >
+                <TagChip tag={tg} />
+              </span>
+            ))}
+            <span ref={pillRef} className={pillClass}>
+              +{attached.length}
+            </span>
+          </div>
+
+          <div ref={rowRef} className="flex items-center gap-1 min-w-0 flex-1 overflow-hidden">
+            {attached.slice(0, visible).map((tg) => (
+              <TagChip
+                key={tg.id}
+                tag={tg}
+                onClick={onChipClick ? () => onChipClick(tg.id, tg.name) : undefined}
+                title={
+                  onChipClick ? t("channels.row.filterFeedByTag", { name: tg.name }) : undefined
+                }
+              />
+            ))}
+            {hidden > 0 && (
+              <button
+                ref={overflowPop.refs.setReference}
+                type="button"
+                aria-label={t("channels.tags.moreCount", { count: hidden })}
+                className={`${pillClass} hover:text-fg transition`}
+                {...overflowPop.getReferenceProps()}
+              >
+                +{hidden}
+              </button>
+            )}
+          </div>
+        </>
+      )}
+
       {/* Hover: reveal every attached tag when some are collapsed into "+N". */}
       <PopoverSurface
         popover={overflowPop}

frontend/src/components/Channels.tsx

@@ -4,7 +4,8 @@ import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
 import { qk } from "../lib/queryKeys";
 import { Ban, Eye, EyeOff, History, LayoutGrid, Pencil, RefreshCw, Table, X } from "lucide-react";
 import ExcludedChannelList from "./ExcludedChannelList";
-import { api, type ManagedChannel } from "../lib/api";
+import { api, NO_TAG_SENTINEL, type ManagedChannel } from "../lib/api";
+import { Sparkles } from "lucide-react";
 import { notifyYouTubeActionError } from "../lib/youtubeErrors";
 import { accountKey, LS } from "../lib/storage";
 import { buildChannelColumns, applySyncFilter } from "./channelColumns";
@@ -15,10 +16,12 @@ import Tabs, { type TabDef } from "./Tabs";
 import ChannelLayoutGrid from "./ChannelLayoutGrid";
 import { LoadingState, StateMessage } from "./QueryState";
 import { useChannelTagActions } from "../lib/useChannelTagActions";
+import { useTagSuggestions } from "./useTagSuggestions";
 import { useChannelPriority } from "../lib/useChannelPriority";
 import ViewSwitcher, { type ViewOption } from "./ViewSwitcher";
 import ColumnSortControl from "./ColumnSortControl";
-import FilterChipGroup, { filterChipClass } from "./FilterChipGroup";
+import FilterChipGroup from "./FilterChipGroup";
+import TagFilterChips, { type FilterChip } from "./TagFilterChips";
 import ActionMenu, { type ActionMenuItem } from "./ActionMenu";
 import ChannelStatsPopover from "./ChannelStatsPopover";
 import Pager from "./Pager";
@@ -164,10 +167,37 @@ export default function Channels() {
         ),
       ),
     // Keep the channel DETAIL cache in step with the manager list (the detail page reads its tags
-    // from qk.channel(id)); mirrors the detail page invalidating the manager list on its side.
-    onSuccess: (id) => qc.invalidateQueries({ queryKey: qk.channel(id) }),
-    onError: () => qc.invalidateQueries({ queryKey: qk.channels() }),
+    // from qk.channel(id)); mirrors the detail page invalidating the manager list on its side. Also
+    // recompute suggestions: a channel that just gained/lost a user tag changes the untagged set and
+    // the learned pattern (E8·S4).
+    onSuccess: (id) => {
+      qc.invalidateQueries({ queryKey: qk.channel(id) });
+      qc.invalidateQueries({ queryKey: qk.tagSuggestions() });
+    },
+    // A failed attach/detach reverts the optimistic change by refetching the list. Also refetch
+    // suggestions: acceptSuggestion optimistically dropped the channel from that cache, and on
+    // failure the tag never actually attached — so the server still suggests it and the ghost chips
+    // must come back rather than leaving an empty cell (honest states). Surface the write failure too.
+    onError: () => {
+      qc.invalidateQueries({ queryKey: qk.channels() });
+      qc.invalidateQueries({ queryKey: qk.tagSuggestions() });
+      notify({ level: "error", message: t("channels.tags.updateFailed") });
+    },
   });
+  // --- Suggested tags (E8·S4): learned from the user's own manual-tag pattern, shown as accept/dismiss
+  // ghost chips on untagged channels. Dismissal is session-only (an accepted suggestion self-clears —
+  // the channel becomes tagged and the server drops it; a dismissed one just hides until reload). The
+  // /tags/suggestions query, the session dismiss set, and the optimistic accept/dismiss/bulk logic all
+  // live in useTagSuggestions so they can be unit-tested apart from this component.
+  const {
+    suggestionsFor,
+    dismissSuggestion,
+    acceptSuggestion,
+    visibleSuggestions,
+    highConfidence,
+    acceptAllHighConfidence,
+  } = useTagSuggestions({ tags: tagsQuery.data ?? [], toggleTag });
+
   const syncSubs = useMutation({
     mutationFn: () => api.syncSubscriptions(),
     onSuccess: (r: { subscriptions?: number }) => {
@@ -217,11 +247,34 @@ export default function Channels() {
   // funnel share ONE state and stay in sync (bidirectional). Toggling a chip rewrites `filters.tags`;
   // filterRows / DataTable then applies it. Channel-name search stays separate (the shared top box).
   const tagFilter = Array.isArray(filters.tags) ? filters.tags : [];
+  // Picking a real tag drops the "No tag" sentinel (item B) — they're mutually exclusive, as in the feed.
   const toggleTagFilter = (tagId: number) => {
     const id = String(tagId);
-    const next = tagFilter.includes(id) ? tagFilter.filter((x) => x !== id) : [...tagFilter, id];
+    const base = tagFilter.filter((x) => x !== NO_TAG_SENTINEL);
+    const next = base.includes(id) ? base.filter((x) => x !== id) : [...base, id];
     setFilters({ ...filters, tags: next });
   };
+  // The "No tag" chip: filter the table to channels you haven't personally tagged yet. Exclusive with
+  // real tag chips (clicking it drops them); the Tags column's test reads the sentinel (channelColumns).
+  const noTagOn = tagFilter.includes(NO_TAG_SENTINEL);
+  const toggleNoTagFilter = () =>
+    setFilters({ ...filters, tags: noTagOn ? [] : [NO_TAG_SENTINEL] });
+  // The tag-filter chips (user tags + the "No tag" sentinel), fed to TagFilterChips which folds any
+  // overflow into a "+N" pill so the row stays one line and the trailing "…" actions can't wrap.
+  const tagFilterChips: FilterChip[] = [
+    ...userTags.map((tg) => ({
+      key: `t${tg.id}`,
+      label: tg.name,
+      active: tagFilter.includes(String(tg.id)),
+      onToggle: () => toggleTagFilter(tg.id),
+    })),
+    {
+      key: NO_TAG_SENTINEL,
+      label: t("channels.tags.noTag"),
+      active: noTagOn,
+      onToggle: toggleNoTagFilter,
+    },
+  ];
   // A focus-channel intent (header "without full history" / tag manager) seeds the search box.
   useEffect(() => {
     if (focusChannelName) setSearch(focusChannelName);
@@ -295,6 +348,9 @@ export default function Channels() {
     toggleTag,
     createAndAttachTag,
     onFilterByTag,
+    suggestionsFor,
+    onAcceptSuggestion: acceptSuggestion,
+    onDismissSuggestion: dismissSuggestion,
   });
 
   // Status chips sit in the table's controls row (next to paging) — compact and close to
@@ -426,41 +482,52 @@ export default function Channels() {
         {tabs}
         {view === "subscribed" && (
           <div className="px-4 pt-2 pb-2 max-w-384 mx-auto">
-            {/* Your tags (left) share one row with the two catalog-wide actions (right); the channel-name
-          search lives in the shared top SearchBar, tag create/delete in the manager. */}
-            <div className="flex items-center justify-between gap-4 flex-wrap">
-              <div className="flex flex-wrap items-center gap-1.5">
-                {/* The "TAGS" label IS the tags-editor trigger (pencil), replacing the separate
-                    "Manage tags" button; the tooltip explains what tags are + that it's clickable. */}
-                <Tooltip hint={t("channels.tags.yourTagsHint")}>
-                  <button
-                    onClick={() => setTagManagerOpen(true)}
-                    className="mr-1 inline-flex items-center gap-1.5 rounded-lg border border-border px-2 py-1 text-xs uppercase tracking-wide text-muted transition hover:border-accent hover:text-accent"
-                  >
-                    <Pencil className="h-3 w-3" />
-                    {t("channels.tags.label")}
-                  </button>
-                </Tooltip>
-                {userTags.map((tg) => (
-                  <button
-                    key={tg.id}
-                    onClick={() => toggleTagFilter(tg.id)}
-                    aria-pressed={tagFilter.includes(String(tg.id))}
-                    className={filterChipClass}
-                  >
-                    {tg.name}
-                  </button>
-                ))}
-                {tagFilter.length > 0 && (
-                  <button
-                    onClick={() => setFilters({ ...filters, tags: [] })}
-                    className="text-xs px-2 py-1 text-muted hover:text-accent transition"
-                  >
-                    {t("datatable.clear")}
-                  </button>
-                )}
-              </div>
-              {actionButtons}
+            {/* One non-wrapping row: the TAGS editor trigger (left) + the tag-filter chip lane (folds
+          overflow into "+N") + Clear, then the catalog "…" actions pinned right. It never wraps, so the
+          "…" menu always stays on the first line. Channel-name search lives in the shared top SearchBar. */}
+            <div className="flex items-center gap-2 min-w-0">
+              {/* The "TAGS" label IS the tags-editor trigger (pencil), replacing the separate
+                  "Manage tags" button; the tooltip explains what tags are + that it's clickable. */}
+              <Tooltip hint={t("channels.tags.yourTagsHint")}>
+                <button
+                  onClick={() => setTagManagerOpen(true)}
+                  className="shrink-0 inline-flex items-center gap-1.5 rounded-lg border border-border px-2 py-1 text-xs uppercase tracking-wide text-muted transition hover:border-accent hover:text-accent"
+                >
+                  <Pencil className="h-3 w-3" />
+                  {t("channels.tags.label")}
+                </button>
+              </Tooltip>
+              <TagFilterChips chips={tagFilterChips} className="flex-1" />
+              {tagFilter.length > 0 && (
+                <button
+                  onClick={() => setFilters({ ...filters, tags: [] })}
+                  className="shrink-0 text-xs px-2 py-1 text-muted hover:text-accent transition"
+                >
+                  {t("datatable.clear")}
+                </button>
+              )}
+              {/* Suggested-tags affordance (E8·S4): a sparkle count of the visible suggestions, with a
+                  one-click bulk-accept for the high-confidence ones. The per-row ghost chips handle the
+                  rest. Hidden when there's nothing to suggest. */}
+              {visibleSuggestions.length > 0 && (
+                <div className="shrink-0 flex items-center gap-1.5">
+                  <Tooltip hint={t("channels.tags.suggestionsHint")}>
+                    <span className="inline-flex items-center gap-1 rounded-lg border border-dashed border-accent/50 px-2 py-1 text-xs text-accent/90">
+                      <Sparkles className="h-3 w-3" />
+                      {t("channels.tags.suggestionsCount", { count: visibleSuggestions.length })}
+                    </span>
+                  </Tooltip>
+                  {highConfidence.length > 0 && (
+                    <button
+                      onClick={acceptAllHighConfidence}
+                      className="text-xs px-2 py-1 rounded-lg border border-border text-muted hover:border-accent hover:text-accent transition"
+                    >
+                      {t("channels.tags.acceptAllHigh", { count: highConfidence.length })}
+                    </button>
+                  )}
+                </div>
+              )}
+              <div className="shrink-0">{actionButtons}</div>
             </div>
           </div>
         )}

frontend/src/components/ChannelsProvider.dom.test.tsx

@@ -17,6 +17,7 @@ vi.mock("./NavigationProvider", () => ({
 }));
 
 import { ChannelsProvider, useChannels, useChannelsActions } from "./ChannelsProvider";
+import { setActiveAccount } from "../lib/api/core";
 
 const wrapper = ({ children }: { children: ReactNode }) => (
   <ChannelsProvider>{children}</ChannelsProvider>
@@ -27,7 +28,10 @@ const VIEW_KEY = "siftlode.channelsView.1"; // account-scoped (accountKey suffix
 beforeEach(() => {
   localStorage.clear();
   sessionStorage.setItem("siftlode.activeAccount", "1"); // pin the tab's account
-  window.history.replaceState({ sfPage: "channels" }, ""); // setView only owns an entry on this page
+  // Reset BOTH the history state and the query string: setView only owns an entry on the channels page,
+  // and the S8 URL mirror writes ctab/csort/cf — a stale key left by a prior test would be read back by
+  // this provider's mount-time URL seed and change the starting tab.
+  window.history.replaceState({ sfPage: "channels" }, "", "/");
 });
 
 describe("ChannelsProvider tab history", () => {
@@ -71,3 +75,58 @@ describe("ChannelsProvider tab history", () => {
     expect(result.current.view).toBe("hidden"); // unchanged
   });
 });
+
+describe("ChannelsProvider — S8 shareable URL", () => {
+  it("seeds tab + sort + filters from a shared manager link at mount (URL wins over stored)", () => {
+    // Stored view says "blocked"; the shared link says "hidden" + a sort + a filter → the URL wins.
+    localStorage.setItem(VIEW_KEY, "blocked");
+    const cf = encodeURIComponent(JSON.stringify({ sync: "needsFull" }));
+    window.history.replaceState(
+      { sfPage: "channels" },
+      "",
+      `/?ctab=hidden&csort=priority:desc&cf=${cf}`,
+    );
+    const { result } = render();
+    expect(result.current.view).toBe("hidden");
+    expect(result.current.sort).toEqual({ key: "priority", dir: "desc" });
+    expect(result.current.filters).toEqual({ sync: "needsFull" });
+  });
+
+  it("mirrors the tab into the address bar and clears it back to the default", () => {
+    const { result } = render();
+    act(() => result.current.setView("blocked"));
+    expect(new URLSearchParams(window.location.search).get("ctab")).toBe("blocked");
+    // Back to the default tab clears the key (only non-defaults are emitted).
+    act(() => result.current.setView("subscribed"));
+    expect(new URLSearchParams(window.location.search).has("ctab")).toBe(false);
+  });
+
+  it("a PARTIAL shared link (fresh tab) does not clobber the account's stored sort/filters", () => {
+    // Regression: on a fresh tab the account pins AFTER mount, so the seed's base for the OMITTED
+    // dimensions was read as defaults. Persisting the whole seed used to overwrite the account's real
+    // stored sort + filter map. The fix persists ONLY the URL-present dimensions.
+    localStorage.setItem(
+      "siftlode.channelSort.1",
+      JSON.stringify({ key: "subscribers", dir: "desc" }),
+    );
+    localStorage.setItem("siftlode.channelsFilterMap.1", JSON.stringify({ sync: "needsFull" }));
+    sessionStorage.removeItem("siftlode.activeAccount"); // account not pinned yet at mount
+    window.history.replaceState({ sfPage: "channels" }, "", "/?ctab=hidden"); // only the tab in the URL
+
+    const { result } = render();
+    act(() => setActiveAccount(1)); // App pins the account after /api/me
+
+    // The present dim (tab) is adopted from the link...
+    expect(result.current.view).toBe("hidden");
+    // ...but the omitted sort + filters keep the account's real stored values, in state AND storage.
+    expect(result.current.sort).toEqual({ key: "subscribers", dir: "desc" });
+    expect(result.current.filters).toEqual({ sync: "needsFull" });
+    expect(JSON.parse(localStorage.getItem("siftlode.channelSort.1")!)).toEqual({
+      key: "subscribers",
+      dir: "desc",
+    });
+    expect(JSON.parse(localStorage.getItem("siftlode.channelsFilterMap.1")!)).toEqual({
+      sync: "needsFull",
+    });
+  });
+});

frontend/src/components/ChannelsProvider.tsx

@@ -3,16 +3,25 @@ import {
   useCallback,
   useContext,
   useEffect,
+  useLayoutEffect,
   useMemo,
   useRef,
   useState,
   type ReactNode,
 } from "react";
-import { getAccountRaw, LS } from "../lib/storage";
+import { getAccountRaw, setAccountRaw, LS } from "../lib/storage";
 import { parseChannelLayout, type ChannelLayout } from "../lib/channelLayout";
-import { type SortState } from "../lib/columnSort";
+import { hydrateSort, type SortState } from "../lib/columnSort";
 import { useSortState } from "../lib/useSortState";
 import { useFilterState } from "../lib/useFilterState";
+import { useActiveAccountId } from "../lib/activeAccount";
+import { useUrlMirror } from "../lib/useUrlMirror";
+import {
+  channelsParamsToState,
+  channelsParamUpdates,
+  hasChannelsParams,
+  type ChannelsUrlState,
+} from "../lib/channelsUrlState";
 import { usePersistedTab } from "./Tabs";
 import type { FilterMap } from "./tableHeader";
 import { useNavigation, useNavigationActions } from "./NavigationProvider";
@@ -44,6 +53,47 @@ function migrateSyncChip(): FilterMap | null {
   return null;
 }
 
+// The manager's stored column-filter map, healed to a plain string/string[] object (same discipline as
+// useFilterState's hydrate). Used only to build the seed's base — the URL keeps whatever the stored map
+// has for any dimension a partial shared link omits.
+function readStoredFilters(): FilterMap {
+  const raw = getAccountRaw(LS.channelsFilterMap);
+  if (raw) {
+    try {
+      const v = JSON.parse(raw);
+      if (v && typeof v === "object" && !Array.isArray(v)) return v as FilterMap;
+    } catch {
+      /* fall through to the migrate seed */
+    }
+  }
+  return migrateSyncChip() ?? {};
+}
+
+// S8: a shared manager link carries the content state in namespaced URL keys (ctab/csort/cf). When
+// present, the URL wins over this account's stored view — read once at mount and applied over the slice
+// hooks (see the provider). The keys are channels-unique, so their mere presence identifies a shared
+// manager view; no ?page check is needed (the mirror below is page-gated so it never pollutes others).
+// The seed = the URL-merged state PLUS which dimensions the URL actually carried. `present` matters
+// because the base below is read at MOUNT, before the account is pinned (getAccountRaw returns null),
+// so an OMITTED dimension's base is a default, not this account's stored value. The provider seeds and
+// persists only the PRESENT dimensions and lets the absent ones re-hydrate from storage normally —
+// otherwise a partial shared link silently resets the omitted stored sort / filter map.
+type ChannelsSeedPresent = { view: boolean; sort: boolean; filters: boolean };
+type ChannelsUrlSeed = { state: ChannelsUrlState; present: ChannelsSeedPresent };
+function readChannelsUrlSeed(): ChannelsUrlSeed | null {
+  const params = new URLSearchParams(window.location.search);
+  if (!hasChannelsParams(params)) return null;
+  const state = channelsParamsToState(params, {
+    view: clampView(getAccountRaw(LS.channelsView)),
+    sort: hydrateSort(getAccountRaw(LS.channelSort), [], null),
+    filters: readStoredFilters(),
+  });
+  return {
+    state,
+    present: { view: params.has("ctab"), sort: params.has("csort"), filters: params.has("cf") },
+  };
+}
+
 type ChannelsState = {
   search: string;
   // The subscribed table's column filters, lifted out of DataTable so the top status chips, the Sync
@@ -132,6 +182,45 @@ export function ChannelsProvider({ children }: { children: ReactNode }) {
   const [focusName, setFocusName] = useState<string | null>(null);
   const [focusToken, setFocusToken] = useState(0);
 
+  // S8 — shareable manager view. Captured once at mount (or null when no manager URL keys are present).
+  const [urlSeed] = useState(readChannelsUrlSeed);
+  const accountId = useActiveAccountId();
+  const seededRef = useRef(false);
+  const persistedRef = useRef(false);
+
+  // Apply the shared-link seed once, BEFORE paint, through the slice setters. Going through the setters
+  // (not raw state) is deliberate: each one calls its hook's markDirty, so the account-pin re-hydrate
+  // (which fires later on a fresh tab) sees the slice as user-edited and won't reload the stored view
+  // over the shared one. setViewRaw (not setView) restores the tab without pushing a phantom history
+  // entry. A normal load has urlSeed === null and this is a no-op.
+  useLayoutEffect(() => {
+    if (!urlSeed || seededRef.current) return;
+    seededRef.current = true;
+    // Only apply the dimensions the URL actually carried. An omitted dimension must NOT go through its
+    // setter (which would markDirty and block the account-pin re-hydrate from loading the stored value)
+    // — leave it to hydrate from storage normally. Fixes a partial link wiping the stored sort/filters.
+    const { state, present } = urlSeed;
+    if (present.view && state.view !== view) setViewRaw(state.view);
+    if (present.filters) setFilters(state.filters);
+    if (present.sort) setSort(state.sort);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+
+  // On a fresh tab the account pins AFTER mount, so the seed's setter writes above no-op'd (no account
+  // yet). Persist the seed to the account once it's known, so the shared view also survives a later
+  // PLAIN reload (no URL) — mirrors PlexProvider's rehydrate-persist. The slice hooks' own re-hydrate
+  // already skips (marked dirty above), so this only touches storage, not state.
+  useEffect(() => {
+    if (!urlSeed || accountId == null || persistedRef.current) return;
+    persistedRef.current = true;
+    // Persist ONLY the URL-present dimensions — the omitted ones were seeded from mount-time defaults
+    // (no account yet), so writing them here would overwrite the account's real stored sort/filter map.
+    const { state, present } = urlSeed;
+    if (present.view) setAccountRaw(LS.channelsView, state.view);
+    if (present.filters) setAccountRaw(LS.channelsFilterMap, JSON.stringify(state.filters));
+    if (present.sort) setAccountRaw(LS.channelSort, JSON.stringify(state.sort));
+  }, [urlSeed, accountId]);
+
   // Latest-value ref so the STABLE setView can compare against the current tab without depending on
   // it (a dep would recreate the action on every switch and re-render every actions consumer).
   // Written during render — the sanctioned pattern NavigationProvider uses for `pageRef`.
@@ -218,6 +307,12 @@ export function ChannelsProvider({ children }: { children: ReactNode }) {
     [setSearch, setFilters, setView, setLayout, setSort, focusChannel, goToFullHistory],
   );
 
+  // S8: mirror the content state (tab + sort + column filters) into the address bar under the namespaced
+  // keys so a manager view is shareable. Gated on page===channels: off the manager the keys are cleared
+  // (localStorage still holds the state; it re-mirrors on return). The name `search` stays OUT — it's a
+  // deliberately transient rail-search, like the feed's and plex's.
+  useUrlMirror(channelsParamUpdates(page === "channels" ? { view, sort, filters } : null));
+
   return (
     <ActionsContext.Provider value={actions}>
       <LayoutContext.Provider value={layout}>

frontend/src/components/ConfigPanel.tsx

@@ -6,6 +6,8 @@ import { Plug, RotateCcw, Send } from "lucide-react";
 import { api, type ConfigItem, type PlexTestResult } from "../lib/api";
 import { notify } from "../lib/notifications";
 import Tooltip from "./Tooltip";
+import InlineNotice from "./InlineNotice";
+import { useMe } from "../lib/useMe";
 import Tabs, { usePersistedTab } from "./Tabs";
 import { LoadingState, StateMessage } from "./QueryState";
 import { PageToolbar } from "./PageShell";
@@ -35,6 +37,7 @@ const GROUP_ORDER = [
 export default function ConfigPanel() {
   const { t } = useTranslation();
   const qc = useQueryClient();
+  const me = useMe();
   const q = useQuery({ queryKey: qk.adminConfig(), queryFn: api.adminConfig });
   const data = q.data;
 
@@ -100,6 +103,10 @@ export default function ConfigPanel() {
         }
       }
       await qc.invalidateQueries({ queryKey: qk.adminConfig() });
+      // The email-not-configured notice reads me.email_configured, which is otherwise only
+      // refetched on its own 60s interval — without this it keeps warning about fields the admin
+      // has just filled in, which reads as the save not having taken.
+      await qc.invalidateQueries({ queryKey: qk.me() });
       setReseedToken((n) => n + 1); // re-seed the draft from the saved server state
       setSaveState("saved");
       setTimeout(() => setSaveState((s) => (s === "saved" ? "idle" : s)), 2500);
@@ -204,7 +211,11 @@ export default function ConfigPanel() {
             </div>
 
             {activeGroup === "email" && (
-              <div className="mt-3 pt-3 border-t border-border/60">
+              <div className="mt-3 pt-3 border-t border-border/60 space-y-3">
+                {/* The one place an operator can see that mail is off. Sending is fail-soft, so a
+                    half-filled config costs verification links, resets and access-request notices
+                    with no error anywhere — say so next to the fields that fix it. */}
+                {!me.email_configured && <InlineNotice>{t("config.emailOff")}</InlineNotice>}
                 <Tooltip hint={t("config.testEmailHint")}>
                   <button
                     onClick={() => testEmail.mutate()}