feat(player): the OS media controls, the basic keys and resume for the library and shared-link players

Plex, library and /watch tell the operating system what plays (title, line, picture) and take its
play / pause / skip / seek through one hook (lib/mediaSession); the Plex player drives it with its own
seek and clock, so the lock screen shows the film's position, not the stream's. The YouTube player is
left alone: its iframe already publishes all of it, and the OS routes to the frame that plays.

The library and /watch players get the basic keys (lib/mediaKeys, the keymap's mediaPlayer rows) and
open where the viewer stopped (lib/resume): the library keeps the point on the server, per user and
library item (library_states, POST /api/downloads/{id}/progress, listed back on both listings), the
shared link in this browser. A started library row continues, its menu can start it over, and its
picture carries the cards' progress bar. The resume rule (too early / near the end = from the start)
is one function shared with the YouTube route.

The library dialog opens focused on its panel (Modal initialFocus "player"): on the ✕, Space closed
the film. While the media element itself has the focus, Space and the arrows stay its own controls'
— the browser acts on them whatever a listener does, and one Space played and paused.

backend/.basedpyright/baseline.json

@@ -743,14 +743,6 @@
                     "lineCount": 1
                 }
             },
-            {
-                "code": "reportArgumentType",
-                "range": {
-                    "startColumn": 37,
-                    "endColumn": 47,
-                    "lineCount": 1
-                }
-            },
             {
                 "code": "reportArgumentType",
                 "range": {

backend/alembic/versions/0099_library_states.py

@@ -0,0 +1,42 @@
+"""library: a resume point per user and library item
+
+The library player opened every item at 0:00. `library_states` keeps where a user stopped, per job
+(their own download, or one shared with them) — the same shape as `video_states`' position, without a
+status: the library has no "watched". It starts empty; the downgrade drops it.
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0099_library_states"
+down_revision: str | None = "0098_drop_demo_account"
+branch_labels: str | None = None
+depends_on: str | None = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "library_states",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column(
+            "user_id",
+            sa.Integer(),
+            sa.ForeignKey("users.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column(
+            "job_id",
+            sa.Integer(),
+            sa.ForeignKey("download_jobs.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column("position_seconds", sa.Integer(), nullable=False),
+        sa.Column("progress_updated_at", sa.DateTime(timezone=True), nullable=False),
+        sa.UniqueConstraint("user_id", "job_id", name="uq_library_user_job"),
+    )
+    op.create_index("ix_library_states_job_id", "library_states", ["job_id"])
+
+
+def downgrade() -> None:
+    op.drop_index("ix_library_states_job_id", table_name="library_states")
+    op.drop_table("library_states")

backend/app/models.py

@@ -462,6 +462,27 @@ class VideoState(Base, UpdatedAtMixin):
     progress_updated_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
 
 
+class LibraryState(Base):
+    """Where a user stopped in a library item (their own download, or one shared with them) — the
+    library player's resume point. Keyed by the JOB, not the file: a job is the user's library entry,
+    a re-download keeps it, and deleting the job deletes the row; the shared file under it may outlive
+    both. A revoked share leaves its recipient's row behind, unread — only a job the user can still
+    reach is ever read or written — and it is back if the item is shared again. Rows exist only for a
+    position worth keeping (see `routes._common.kept_position`); no row means "from the start"."""
+
+    __tablename__ = "library_states"
+    __table_args__ = (UniqueConstraint("user_id", "job_id", name="uq_library_user_job"),)
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    user_id: Mapped[int] = mapped_column(ForeignKey("users.id", ondelete="CASCADE"))
+    job_id: Mapped[int] = mapped_column(
+        ForeignKey("download_jobs.id", ondelete="CASCADE"), index=True
+    )
+    # int4: a checkpoint body must stay under POSITION_MAX_S, or the flush is a DataError (a 500).
+    position_seconds: Mapped[int] = mapped_column(Integer, nullable=False)
+    progress_updated_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
+
+
 class SearchFind(Base, TimestampMixin):
     """Per-user record of a video the user surfaced via their own live YouTube search.
 

backend/app/routes/_common.py

@@ -9,16 +9,51 @@ one existence-leak policy.
 from typing import IO, Any, TypeVar
 
 from fastapi import HTTPException, Request
+from pydantic import BaseModel, ConfigDict, Field
 from sqlalchemy.orm import Session
 
 from app.db import Base
-from app.models import User
+from app.models import POSITION_MAX_S, User
 from app.issues import gitea
 from app.refusal import refused
 from app.youtube.client import YouTubeError, refusal_reason
 
 M = TypeVar("M", bound=Base)
 
+# Resume-position thresholds of a player that only keeps a resume point (the YouTube player, the
+# library's): positions below this are "didn't really start" and within this of the end are
+# "basically finished" — neither is worth storing, so the position is cleared instead (no progress
+# bar). The client's local resume (`lib/resume.ts`) keeps the same two numbers. NB: the Plex player
+# intentionally uses a LARGER finish margin (30s) because it marks long-form items watched, not just
+# clears a resume bar — see routes/plex/playback.py.
+PROGRESS_MIN_SECONDS = 5
+FINISH_MARGIN_SECONDS = 10
+
+
+class ProgressIn(BaseModel):
+    """A player's resume checkpoint (sent every few seconds while it plays, and as a beacon when the
+    page goes away)."""
+
+    # Finite only: JSON parsing here accepts `Infinity`/`NaN`, and the handler's `int()` turned
+    # one into a 500.
+    model_config = ConfigDict(allow_inf_nan=False)
+
+    # Accept a float and truncate (`kept_position`) — the player may post a raw currentTime (a float),
+    # which the old `int(payload.get(...))` silently truncated. A plain `int` field would 422 that on
+    # the progress hot path, losing the resume position; `float` keeps the old tolerance.
+    # Bounded above by the int4 column (see POSITION_MAX_S): past it the flush was a 500.
+    position_seconds: float = Field(0, le=POSITION_MAX_S)
+    duration_seconds: float = Field(0, le=POSITION_MAX_S)
+
+
+def kept_position(body: ProgressIn) -> int:
+    """The whole-second resume point worth storing for `body`, or 0 for "clear it" (too early to
+    count as started, or close enough to the end to count as finished)."""
+    position = max(0, int(body.position_seconds))
+    duration = int(body.duration_seconds)
+    near_end = duration > 0 and position > duration - FINISH_MARGIN_SECONDS
+    return position if position >= PROGRESS_MIN_SECONDS and not near_end else 0
+
 
 def not_found(what: str = "generic") -> HTTPException:
     """The 404 for a row that is gone — structured, so the bilingual UI says it in the reader's

backend/app/routes/downloads.py

@@ -8,7 +8,7 @@ state, serves finished files (range-aware, with the user's custom display name),
 import os
 import re
 import tempfile
-from collections.abc import AsyncIterator
+from collections.abc import AsyncIterator, Sequence
 from dataclasses import dataclass
 from datetime import datetime, timedelta, timezone
 from pathlib import Path
@@ -17,7 +17,8 @@ from urllib.parse import parse_qs, unquote, urlparse
 from fastapi import APIRouter, Depends, HTTPException, Request
 from fastapi.responses import FileResponse
 from pydantic import BaseModel
-from sqlalchemy import func, select
+from sqlalchemy import delete, func, select
+from sqlalchemy.dialects.postgresql import insert as pg_insert
 from sqlalchemy.orm import Session
 
 from app.mailtext import lang_for_user
@@ -39,11 +40,19 @@ from app.models import (
     DownloadProfile,
     DownloadQuota,
     DownloadShare,
+    LibraryState,
     MediaAsset,
     User,
     display_text,
 )
-from app.routes._common import capped_stream_to, get_or_404, not_found, owned_or_404
+from app.routes._common import (
+    ProgressIn,
+    capped_stream_to,
+    get_or_404,
+    kept_position,
+    not_found,
+    owned_or_404,
+)
 from app.security import hash_password
 from app.userscope import is_messageable_user, messageable_clauses
 from app.utils import iso
@@ -165,6 +174,19 @@ def _assets_for(db: Session, jobs: list[DownloadJob]) -> dict[int, MediaAsset]:
     return {a.id: a for a in rows}
 
 
+def _positions_for(db: Session, user: User, jobs: Sequence[DownloadJob]) -> dict[int, int]:
+    """`user`'s resume point in each of `jobs` that has one (the library player's `library_states`)."""
+    ids = [j.id for j in jobs]
+    if not ids:
+        return {}
+    rows = db.execute(
+        select(LibraryState.job_id, LibraryState.position_seconds).where(
+            LibraryState.user_id == user.id, LibraryState.job_id.in_(ids)
+        )
+    ).all()
+    return {job_id: pos for job_id, pos in rows}
+
+
 def _serialize_job(db: Session, job: DownloadJob) -> dict:
     """Resolve a job's cache asset (if any) and serialize the pair — the resolve-then-serialize step
     every single-job handler shares."""
@@ -573,7 +595,14 @@ def list_downloads(user: User = Depends(current_user), db: Session = Depends(get
         .all()
     )
     assets = _assets_for(db, jobs)
-    return [_serialize(j, assets.get(j.asset_id)) for j in jobs]
+    positions = _positions_for(db, user, jobs)
+    return [
+        {
+            **_serialize(j, assets.get(j.asset_id) if j.asset_id is not None else None),
+            "position_seconds": positions.get(j.id, 0),
+        }
+        for j in jobs
+    ]
 
 
 @router.get("/usage")
@@ -634,10 +663,12 @@ def shared_with_me(user: User = Depends(current_user), db: Session = Depends(get
         .all()
     )
     assets = _assets_for(db, jobs)
+    positions = _positions_for(db, user, jobs)
     out = []
     for j in jobs:
         data = _serialize(j, assets.get(j.asset_id))
         data["shared"] = True
+        data["position_seconds"] = positions.get(j.id, 0)
         out.append(data)
     return out
 
@@ -825,6 +856,39 @@ def download_file(
 # --- editor filmstrip (scrub track) --------------------------------------------------------
 
 
+@router.post("/{job_id}/progress")
+def set_library_progress(
+    job_id: int,
+    body: ProgressIn,
+    user: User = Depends(current_user),
+    db: Session = Depends(get_db),
+) -> dict:
+    """Checkpoint the library player's resume point in a download the caller can play (their own, or
+    one shared with them). A position too early or too close to the end clears it instead."""
+    _accessible_job(db, user, job_id)
+    position = kept_position(body)
+    mine = (LibraryState.user_id == user.id) & (LibraryState.job_id == job_id)
+    if not position:
+        # A statement, not a loaded row's delete: the periodic checkpoint and the pagehide beacon of
+        # one stop may both clear it, and the second then deletes nothing rather than failing.
+        db.execute(delete(LibraryState).where(mine))
+        db.commit()
+        return {"ok": True, "job_id": job_id, "position_seconds": 0}
+    now = datetime.now(timezone.utc)
+    # One row per (user, job) even when two checkpoints race (the same pair): an upsert, not a
+    # read-then-insert that the second would fail on the unique key.
+    db.execute(
+        pg_insert(LibraryState)
+        .values(user_id=user.id, job_id=job_id, position_seconds=position, progress_updated_at=now)
+        .on_conflict_do_update(
+            constraint="uq_library_user_job",
+            set_={"position_seconds": position, "progress_updated_at": now},
+        )
+    )
+    db.commit()
+    return {"ok": True, "job_id": job_id, "position_seconds": position}
+
+
 @router.get("/{job_id}/storyboard")
 def storyboard_meta(
     job_id: int, user: User = Depends(current_user), db: Session = Depends(get_db)

backend/app/routes/feed.py

@@ -1,7 +1,7 @@
 from datetime import date, datetime, timezone
 
 from fastapi import APIRouter, Depends, Query
-from pydantic import BaseModel, ConfigDict, Field
+from pydantic import BaseModel
 from sqlalchemy import and_, func, or_, select
 from sqlalchemy.dialects.postgresql import insert as pg_insert
 from sqlalchemy.orm import Session
@@ -26,14 +26,19 @@ from app.feedquery import (
     windowed_relevance_rows,
 )
 from app.models import (
-    POSITION_MAX_S,
     ChannelTag,
     Tag,
     User,
     Video,
     VideoState,
 )
-from app.routes._common import get_or_404, youtube_refusal, not_found
+from app.routes._common import (
+    ProgressIn,
+    get_or_404,
+    kept_position,
+    not_found,
+    youtube_refusal,
+)
 from app.sync.videos import parse_iso8601_duration
 from app.utils import iso
 from app.youtube.client import YouTubeClient, YouTubeError
@@ -44,14 +49,6 @@ router = APIRouter(prefix="/api", tags=["feed"])
 # "saved" used to be a status; it's now membership in the built-in Watch later playlist.
 VALID_STATES = {"new", "watched", "hidden"}
 
-# Resume-position thresholds (mirror the client): positions below this are "didn't
-# really start" and within this of the end are "basically finished" — neither is worth
-# storing, so we clear the position instead (the video shows no progress bar).
-# NB: the Plex player intentionally uses a LARGER finish margin (30s) because it marks
-# long-form items watched, not just clears a resume bar — see routes/plex/playback.py.
-PROGRESS_MIN_SECONDS = 5
-FINISH_MARGIN_SECONDS = 10
-
 
 # Shared query parameters for /feed and /feed/count.
 def _feed_params(
@@ -326,23 +323,10 @@ def clear_video_state(
     return {"ok": True, "video_id": video_id, "status": "new", "position_seconds": 0}
 
 
-class VideoProgressIn(BaseModel):
-    # Finite only: JSON parsing here accepts `Infinity`/`NaN`, and the handler's `int()` turned
-    # one into a 500.
-    model_config = ConfigDict(allow_inf_nan=False)
-
-    # Accept a float and truncate (below) — the player may post a raw currentTime (a float), which
-    # the old `int(payload.get(...))` silently truncated. A plain `int` field would 422 that on the
-    # 10s progress hot path, losing the resume position; `float` keeps the old tolerance.
-    # Bounded above by the int4 column (see POSITION_MAX_S): past it the flush was a 500.
-    position_seconds: float = Field(0, le=POSITION_MAX_S)
-    duration_seconds: float = Field(0, le=POSITION_MAX_S)
-
-
 @router.post("/videos/{video_id}/progress")
 def set_video_progress(
     video_id: str,
-    body: VideoProgressIn,
+    body: ProgressIn,
     user: User = Depends(current_user),
     db: Session = Depends(get_db),
 ) -> dict:
@@ -350,22 +334,15 @@ def set_video_progress(
     Stores a per-user position on the video_states row without touching watch status, so a
     partially-watched video can render a progress bar and match the "in progress" filter.
     Trivially-early and near-finished positions clear the position rather than store it."""
-    position = int(body.position_seconds)
-    duration = int(body.duration_seconds)
-    if position < 0:
-        position = 0
+    position = kept_position(body)
 
     get_or_404(db, Video, video_id, what="video")
 
-    # Decide whether this position is worth keeping (else clear it).
-    near_end = duration > 0 and position > duration - FINISH_MARGIN_SECONDS
-    keep = position >= PROGRESS_MIN_SECONDS and not near_end
-
     row = db.execute(
         select(VideoState).where(VideoState.user_id == user.id, VideoState.video_id == video_id)
     ).scalar_one_or_none()
 
-    if not keep:
+    if not position:
         # Nothing meaningful to store: drop a status-less row entirely, otherwise just
         # zero the position (a saved/hidden video keeps its status).
         if row is not None:

backend/tests/test_library_progress.py

@@ -0,0 +1,121 @@
+"""The library player's resume point (`library_states`).
+
+A checkpoint stores where the caller stopped in a library item they can play — their own download,
+or one shared with them — and the two library listings hand it back per item, so the player opens
+there. Too early or too close to the end clears it. Nobody else's checkpoint, and no item the caller
+cannot reach, is ever read or written. DB-backed (real Postgres).
+"""
+
+from sqlalchemy import select
+
+from app.models import DownloadJob, DownloadShare, LibraryState
+
+
+def _done_job(db, user) -> DownloadJob:
+    job = DownloadJob(
+        user_id=user.id,
+        source_kind="url",
+        source_ref="https://example.com/a.mp4",
+        status="done",
+        profile_snapshot={},
+    )
+    db.add(job)
+    db.commit()
+    return job
+
+
+def _checkpoint(client, job_id: int, position: float, duration: float = 3000) -> int:
+    """Send a checkpoint the caller may make; the point the server kept (0 = cleared)."""
+    r = client.post(
+        f"/api/downloads/{job_id}/progress",
+        json={"position_seconds": position, "duration_seconds": duration},
+    )
+    assert r.status_code == 200, r.text
+    return r.json()["position_seconds"]
+
+
+def _states(db) -> list[tuple[int, int, int]]:
+    db.expire_all()
+    rows = db.execute(
+        select(LibraryState.user_id, LibraryState.job_id, LibraryState.position_seconds)
+    ).all()
+    return [tuple(r) for r in rows]
+
+
+def test_a_checkpoint_is_listed_back_on_the_item(db, make_user, as_user):
+    me = make_user()
+    job = _done_job(db, me)
+    c = as_user(me)
+
+    r = c.post(
+        f"/api/downloads/{job.id}/progress",
+        json={"position_seconds": 754.9, "duration_seconds": 3000},
+    )
+    assert r.status_code == 200 and r.json() == {
+        "ok": True,
+        "job_id": job.id,
+        "position_seconds": 754,
+    }
+
+    [item] = c.get("/api/downloads").json()
+    assert item["position_seconds"] == 754
+    # A second checkpoint moves it rather than adding a row.
+    assert _checkpoint(c, job.id, 900) == 900
+    assert _states(db) == [(me.id, job.id, 900)]
+
+
+def test_an_item_never_played_lists_zero(db, make_user, as_user):
+    me = make_user()
+    _done_job(db, me)
+    [item] = as_user(me).get("/api/downloads").json()
+    assert item["position_seconds"] == 0
+
+
+def test_too_early_or_near_the_end_clears_it(db, make_user, as_user):
+    me = make_user()
+    job = _done_job(db, me)
+    c = as_user(me)
+
+    assert _checkpoint(c, job.id, 600) == 600
+    assert _checkpoint(c, job.id, 2995) == 0
+    assert _states(db) == []
+
+    assert _checkpoint(c, job.id, 600) == 600
+    assert _checkpoint(c, job.id, 3) == 0
+    assert _states(db) == []
+    # Clearing what is not there is not an error (the beacon and the last checkpoint of one stop).
+    assert _checkpoint(c, job.id, 0) == 0
+
+
+def test_a_recipient_keeps_their_own_place_in_a_shared_item(db, make_user, as_user):
+    owner, friend = make_user(), make_user()
+    job = _done_job(db, owner)
+    db.add(DownloadShare(job_id=job.id, from_user_id=owner.id, to_user_id=friend.id))
+    db.commit()
+
+    assert _checkpoint(as_user(owner), job.id, 100) == 100
+    assert _checkpoint(as_user(friend), job.id, 2000) == 2000
+
+    assert as_user(owner).get("/api/downloads").json()[0]["position_seconds"] == 100
+    assert as_user(friend).get("/api/downloads/shared").json()[0]["position_seconds"] == 2000
+
+
+def test_an_item_the_caller_cannot_play_is_a_404_and_writes_nothing(db, make_user, as_user):
+    owner, stranger = make_user(), make_user()
+    job = _done_job(db, owner)
+
+    r = as_user(stranger).post(
+        f"/api/downloads/{job.id}/progress",
+        json={"position_seconds": 600, "duration_seconds": 3000},
+    )
+    assert r.status_code == 404
+    assert _states(db) == []
+
+
+def test_deleting_the_job_deletes_its_places(db, make_user, as_user):
+    me = make_user()
+    job = _done_job(db, me)
+    assert _checkpoint(as_user(me), job.id, 600) == 600
+    db.delete(db.get(DownloadJob, job.id))
+    db.commit()
+    assert _states(db) == []

backend/tests/test_progress_bounds.py

@@ -23,7 +23,10 @@ def client(monkeypatch, override_dep) -> TestClient:
     return TestClient(app)
 
 
-@pytest.mark.parametrize("path", ["/api/videos/v1/progress", "/api/plex/item/98614/progress"])
+@pytest.mark.parametrize(
+    "path",
+    ["/api/videos/v1/progress", "/api/plex/item/98614/progress", "/api/downloads/1/progress"],
+)
 @pytest.mark.parametrize("raw", ["Infinity", "-Infinity", "NaN"])
 def test_a_non_finite_position_is_refused(client, path, raw):
     r = client.post(
@@ -34,7 +37,10 @@ def test_a_non_finite_position_is_refused(client, path, raw):
     assert r.status_code == 422, r.text
 
 
-@pytest.mark.parametrize("path", ["/api/videos/v1/progress", "/api/plex/item/98614/progress"])
+@pytest.mark.parametrize(
+    "path",
+    ["/api/videos/v1/progress", "/api/plex/item/98614/progress", "/api/downloads/1/progress"],
+)
 @pytest.mark.parametrize("field", ["position_seconds", "duration_seconds"])
 def test_a_position_past_the_int4_column_is_refused_not_a_500(client, path, field):
     """Finite but past the int4 column: the flush was a DataError, i.e. a 500 with a traceback."""

backend/tests/test_request_models.py

@@ -7,7 +7,7 @@ from pydantic import ValidationError
 
 from app.routes.channels import AttachTagIn, ChannelUpdateIn
 from app.routes.downloads import AdminSetQuotaIn
-from app.routes.feed import VideoProgressIn
+from app.routes._common import ProgressIn
 from app.routes.setup import SetupAdminIn
 from app.routes.tags import TagUpdateIn
 
@@ -52,10 +52,10 @@ def test_admin_quota_rejects_non_numeric_limit():
 def test_progress_accepts_fractional_seconds():
     # The player may post a raw currentTime (a float). The field must accept it (truncated in the
     # handler) — a plain `int` field would 422 on the progress hot path.
-    assert VideoProgressIn(position_seconds=12.7).position_seconds == 12.7
-    assert int(VideoProgressIn(position_seconds=12.7).position_seconds) == 12
+    assert ProgressIn(position_seconds=12.7).position_seconds == 12.7
+    assert int(ProgressIn(position_seconds=12.7).position_seconds) == 12
     with pytest.raises(ValidationError):
-        VideoProgressIn(position_seconds="not-a-number")
+        ProgressIn(position_seconds="not-a-number")
 
 
 # --- PATCH models: model_fields_set separates "absent" from "explicit null". ---