release: 0.99.0 (feature/e32-gate-integrity)

A form dialog opens on the body's first control, and the composer's first
control is the Edit / Preview switch above the form: the focus landed there,
at open and when a retried load brought the form, and typing went nowhere. A
form can now mark the field to open on (data-initial-focus); every other
dialog keeps its first control. The Modal's comment on the re-armed watch now
says where the focus goes when the focused control is removed but others stay.

.dockerignore

@@ -4,6 +4,7 @@
 *.env.local
 **/__pycache__/
 **/*.pyc
+**/.coverage
 .venv/
 venv/
 # Docker patterns are anchored at the context root with NO implicit `**/` (unlike .gitignore, where

.gitea/workflows/check.yml

@@ -1,7 +1,9 @@
 # Server-side mirror of the local `siftlode check` gate (E1 S3 / DX-1), so `main` is always green
 # independent of any one machine. Two jobs match the two local lanes:
-#   frontend — tsc (3 projects) + eslint + prettier --check + knip + vitest
-#   backend  — ruff + the full pytest suite (pure-logic + the DB-backed lane) against a real Postgres
+#   frontend — tsc (3 projects) + eslint + prettier --check + knip (both modes) + vitest + vite build
+#              + npm audit of the production dependencies
+#   backend  — ruff + basedpyright + the full pytest suite (pure-logic + the DB-backed lane) against
+#              a real Postgres + pip-audit of the lock
 #
 # They are declared side by side but they DO NOT run in parallel: the lab has a single act_runner
 # with one slot, so they queue. Measured across runs #86-#91 — the backend job starts at the exact
@@ -56,6 +58,12 @@ jobs:
       - run: npm run format:check
       - run: npm run knip
       - run: npm run test
+      # The production bundle (E32): before this, `vite build` — and devOnlyGuard, which fails it if
+      # dev-only code reaches the bundle — first ran inside the image build, after main was pushed.
+      - run: npx vite build
+      # What ships to the browser: a known CVE at high or above in a production dependency fails.
+      # (The dev tooling's own advisories are burned down by hand; see docs/gates.md.)
+      - run: npm audit --omit=dev --audit-level=high
 
   backend:
     runs-on: ubuntu-latest
@@ -112,8 +120,9 @@ jobs:
       - name: pytest
         run: python -m pytest
         working-directory: backend
-      # Dependency CVE audit over the pinned lock. Non-blocking for now (informational) — a real CVE
-      # shows up in the run without failing the gate; tighten to a hard fail once the noise is known.
-      - name: pip-audit (advisory)
+      # Dependency CVE audit over the pinned lock. BLOCKING since E32: it ran advisory-only, and when
+      # it was finally read it had three urllib3 advisories with a fix available (bumped in the same
+      # change). An advisory without a fix is answered with `--ignore-vuln <id>` here, a reason and a
+      # date in the comment, and a line in docs/gates.md.
+      - name: pip-audit
         run: pip install --no-cache-dir pip-audit && pip-audit -r backend/requirements.lock
-        continue-on-error: true

.gitignore

@@ -9,6 +9,7 @@ __pycache__/
 venv/
 .mypy_cache/
 .pytest_cache/
+.coverage
 .ruff_cache/
 
 # Node / frontend

.trivyignore.yaml

@@ -0,0 +1,15 @@
+# The CVE gate's allowlist (E32). The publish gate scans the built image and the committed tree with
+# Trivy and fails on any HIGH or CRITICAL finding that has a fix available. A finding that cannot be
+# fixed yet is let through ONLY by an entry here, and every entry carries both:
+#   statement   — why it is acceptable for now (what is exposed, what is not)
+#   expired_at  — the date it stops being accepted; after it, the gate fails again on its own
+# A contract test (frontend/src/lib/gates.contract.test.ts) refuses an entry without either, and
+# docs/gates.md lists them.
+#
+# Example:
+#   vulnerabilities:
+#     - id: CVE-2026-00000
+#       statement: in libfoo's XML path, which nothing in the image calls; no fixed Debian build yet
+#       expired_at: 2026-12-31
+vulnerabilities: []
+secrets: []

CHANGELOG.md

@@ -7,6 +7,25 @@ edit the release notes and re-run the generator.
 
 Upgrading, pinning a version and rolling back: [docs/self-hosting.md](docs/self-hosting.md#upgrading).
 
+## 0.99.0 — 2026-10-04
+
+### New
+
+- Nearly every screen is now compiled by the React Compiler, so lists and menus re-render less.
+- The channel list's row menu opens and closes without redrawing the table.
+
+### Fixed
+
+- A failed or empty answer from YouTube or Plex no longer empties a playlist, a mirror or your Plex watch history: Siftlode keeps what it had until a complete answer arrives.
+- Plex watch states un-watched on Plex now sync for each library on its own, even if another library is briefly unreachable.
+- A channel with no uploads no longer fails its backfill on every run.
+- “This playlist no longer exists” appears only for a list you picked yourself.
+- A filter on a deleted tag matches nothing and its chip says so, and the tag cleanup keeps tags a saved view filters on.
+- A channel filter names its channels from the first moment, and a playlist reopened from the cache keeps its rows.
+- The bug report opens on its title, and a dialog whose form loads late gives the form the focus once.
+- The Plex backdrop crossfade setting is respected even with reduced motion on.
+- Smaller fixes to keyboard focus, undo and loading states.
+
 ## 0.98.0 — 2026-10-03
 
 ### New

CLAUDE.md

@@ -12,12 +12,15 @@ router-free navigation provider.
 
 ## The gate — never merge or ship red
 
-The local gate is **ruff (`check` + `format --check`) + basedpyright (backend) + typecheck (3 tsc projects) + eslint + prettier
---check + knip + vitest + pytest**. It runs on every `publish`, which **refuses to build on failure — there is deliberately no
-`--skip` flag.** Run it and get it green **before** any merge, release, or handing work to review.
+The local gate is **ruff (`check` + `format --check`) + basedpyright (backend) + the lock check + typecheck (3 tsc projects) +
+eslint + prettier --check + knip (both modes) + vitest + vite build + pytest**, then a coverage report (no threshold). It runs
+before every `release` merges and on every `publish`, which **refuses to build on failure — there is deliberately no `--skip`
+flag**; a release also requires the Playwright suite, and the image must pass a Trivy scan before it is pushed. Run it and get it
+green **before** any merge, release, or handing work to review.
 
 - Full gate (agents with the private ops dispatcher): `siftlode check`.
-- Directly, without the dispatcher: `cd frontend && npm run typecheck && npm run lint && npm run knip && npm run test`, plus backend `ruff check backend` + `ruff format --check backend` and `pytest` (the DB-lane needs Postgres).
+- Directly, without the dispatcher: the commands in [`docs/development.md`](docs/development.md) § The gate (frontend lanes, `ruff` over `backend scripts`, basedpyright in the test image, and `pytest` — the DB-lane needs Postgres).
+- **A gate with any real hit is never switched off or narrowed** — not a lint rule, a compiler flag, a lane or a release step. Fix the sites, or suppress each one inline naming its invariant (`-- why`, lint-enforced). What stays narrowed is in [`docs/gates.md`](docs/gates.md), and a contract test fails when a narrowing is missing from it. The effective ESLint config of every file and the CI/lane lines are pinned in `frontend/src/lib/gates.snapshot.json`: a new code file or any gate change fails until you regenerate it (`GATE_SNAPSHOT=update`, see gates.md) — then read that diff as a gate change. A comment saying "X is enforced by Y" is checked by running Y (E32: one such comment hid 95 functions the React Compiler skipped).
 - **The backend type lane runs in the test image, not on the host** — `requirements.lock` cannot be installed on Windows (uvloop), and a type checker without the real packages reports nonsense. It fails on NEW errors only; the pre-existing ones sit in `backend/.basedpyright/baseline.json` and burn down epic by epic. Fixed some? Regenerate with `--writebaseline`.
 - New DB-backed test? It must actually run, not silently skip — assume `SIFTLODE_TEST_REQUIRE_DB=1`.
 
@@ -77,37 +80,39 @@ CQRS, a repository/DI framework, a router library, a generic CRUD-router factory
 
 ## Canonical patterns — when you have a choice, pick THIS
 
-| Area                                 | Use                                                                                                                     | Not                                                                                  |
-| ------------------------------------ | ----------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------ |
-| ORM                                  | SQLAlchemy 2.0 `select()`                                                                                               | `db.query(...)`                                                                      |
-| Request body                         | a Pydantic model                                                                                                        | `payload: dict`                                                                      |
-| Request SIZE                         | nothing — `bodylimit` caps every route (SEC-20); need more? add a ceiling to `ROUTE_MAX_BODY_BYTES`                     | `capped_body` on a route that does not read raw bytes itself                         |
-| Ownership check                      | `owned_or_404` / `get_or_404`                                                                                           | ad-hoc `_own_playlist`/`_owned`/`_own_job`                                           |
-| Admin gate import                    | `app.auth`                                                                                                              | the `app.routes.admin` re-export                                                     |
-| Upstream failure status              | `422` with JSON detail                                                                                                  | `502` (reserve 502 for raw byte-proxies)                                             |
-| User-facing error                    | structured `detail` (`{code, reason}`)                                                                                  | a bare English string under a bilingual UI                                           |
-| Mutation response                    | `{"ok": true, …}` (`{"deleted": id}`), test-held                                                                        | a bare `{"unsubscribed"}`/`{"cleared": n}`, no `ok`                                  |
-| Transaction commit                   | the handler commits; helpers `flush` (test-held list)                                                                   | helpers that commit (only `quota` owns its session)                                  |
-| Admin knob storage                   | `sysconfig` (values)                                                                                                    | env / `app_state` / `scheduler_settings` scatter                                     |
-| Job status word                      | the `downloads/status.py` StrEnum                                                                                       | loose `"canceled"`/`"cancelled"` literals                                            |
-| Current time                         | inline `datetime.now(timezone.utc)`                                                                                     | new `now_utc`/`_now` helpers                                                         |
-| FE per-account state                 | `usePref`                                                                                                               | raw `readAccount`/`writeAccount` or bespoke hooks                                    |
-| FE button                            | `ui/Button` (a `SIZES` rung) · `IconButton` · `Pressable` (a clickable card/row) · `Chip` · `DragHandle`                | a raw `<button>` or `FocusSafeButton` outside the control primitives (lint-enforced) |
-| FE keyboard shortcut                 | a row in `lib/keymap.ts` + `dispatch()`                                                                                 | a private `keydown` listener with its own key literals                               |
-| FE list/grid keys                    | `NavGrid`/`keyboardNav` + `navItemAttrs` + `data-nav-open`                                                              | a private arrow-key / roving-tabindex handler                                        |
-| FE view push (history)               | `rememberNavPosition()` right before `history.pushState`                                                                | a push that forgets: Back strands focus on `<body>`                                  |
-| FE text field / checkbox / slider    | `ui/Input` · `Textarea` · `InnerInput` in a `fieldClass` frame · `Checkbox`/`CheckRow` · `Slider`                       | a raw `<input>`/`<textarea>` anywhere but those primitives (lint-enforced)           |
-| FE glass surface                     | a role: `SURFACE.panel` / `card` / `menu` / `popover` / `tooltip` (`ui/surfaces.ts`)                                    | a bare `glass`/`glass-card`/`glass-menu` beside a hand-picked radius (lint-enforced) |
-| FE static label / button-like link   | `Badge` (flat, no edge) · `LinkButton` / `IconLink`                                                                     | a glass pill that reads as a chip; an `<a>` hand-painted like a button               |
-| FE control                           | `SegmentedToggle`; a long or user's list: `FilterSelect`                                                                | a native `<select>` (lint-enforced)                                                  |
-| FE loading/empty/error               | `QueryState` / `StateMessage`                                                                                           | ad-hoc conditionals                                                                  |
-| FE failed write                      | `meta.failTitle`, else `notifyActionError(err, title)`                                                                  | a bare `catch {}` or `notify()` with no error attached                               |
-| FE network call                      | `req`/`uploadReq`/`beacon`, or `lib/http.ts` `send` (public pages)                                                      | a bare `fetch`/`XMLHttpRequest`/`WebSocket` (lint-enforced)                          |
-| FE diagnostics                       | `lib/log.ts` (`log.info("event.code", msg, attrs)`); a filter change → `lib/filterLog.ts`, a player → `lib/mediaLog.ts` | `console.*` (lint-enforced); a value only a higher level may carry, logged unguarded |
-| FE state that MIRRORS a prop/query   | derive it, or hold a draft (`draft ?? server`)                                                                          | a copy an effect re-syncs — that paints the stale value first                        |
-| FE state reset on a key change       | adjust it DURING render against a remembered key                                                                        | `useEffect(() => setX(init), [key])`                                                 |
-| FE effect that must not re-subscribe | `useEffectEvent` (React 19.2+), else a latest-value ref                                                                 | an excused dep list asserting the same thing in prose                                |
-| FE hook suppression                  | an inline `eslint-disable-next-line` NAMING the invariant                                                               | `eslint-suppressions.json` (deliberately absent — E27 S2)                            |
+| Area                                 | Use                                                                                                                                                                                               | Not                                                                                                                                                     |
+| ------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| ORM                                  | SQLAlchemy 2.0 `select()`                                                                                                                                                                         | `db.query(...)`                                                                                                                                         |
+| Request body                         | a Pydantic model                                                                                                                                                                                  | `payload: dict`                                                                                                                                         |
+| Request SIZE                         | nothing — `bodylimit` caps every route (SEC-20); need more? add a ceiling to `ROUTE_MAX_BODY_BYTES`                                                                                               | `capped_body` on a route that does not read raw bytes itself                                                                                            |
+| Ownership check                      | `owned_or_404` / `get_or_404`                                                                                                                                                                     | ad-hoc `_own_playlist`/`_owned`/`_own_job`                                                                                                              |
+| Admin gate import                    | `app.auth`                                                                                                                                                                                        | the `app.routes.admin` re-export                                                                                                                        |
+| Upstream failure status              | `422` with JSON detail                                                                                                                                                                            | `502` (reserve 502 for raw byte-proxies)                                                                                                                |
+| User-facing error                    | structured `detail` (`{code, reason}`)                                                                                                                                                            | a bare English string under a bilingual UI                                                                                                              |
+| Mutation response                    | `{"ok": true, …}` (`{"deleted": id}`), test-held                                                                                                                                                  | a bare `{"unsubscribed"}`/`{"cleared": n}`, no `ok`                                                                                                     |
+| Transaction commit                   | the handler commits; helpers `flush` (test-held list)                                                                                                                                             | helpers that commit (only `quota` owns its session)                                                                                                     |
+| Admin knob storage                   | `sysconfig` (values)                                                                                                                                                                              | env / `app_state` / `scheduler_settings` scatter                                                                                                        |
+| Job status word                      | the `downloads/status.py` StrEnum                                                                                                                                                                 | loose `"canceled"`/`"cancelled"` literals                                                                                                               |
+| Current time                         | inline `datetime.now(timezone.utc)`                                                                                                                                                               | new `now_utc`/`_now` helpers                                                                                                                            |
+| FE per-account state                 | `usePref`                                                                                                                                                                                         | raw `readAccount`/`writeAccount` or bespoke hooks                                                                                                       |
+| FE button                            | `ui/Button` (a `SIZES` rung) · `IconButton` · `Pressable` (a clickable card/row) · `Chip` · `DragHandle`                                                                                          | a raw `<button>` or `FocusSafeButton` outside the control primitives (lint-enforced)                                                                    |
+| FE keyboard shortcut                 | a row in `lib/keymap.ts` + `dispatch()`                                                                                                                                                           | a private `keydown` listener with its own key literals                                                                                                  |
+| FE list/grid keys                    | `NavGrid`/`keyboardNav` + `navItemAttrs` + `data-nav-open`                                                                                                                                        | a private arrow-key / roving-tabindex handler                                                                                                           |
+| FE view push (history)               | `rememberNavPosition()` right before `history.pushState`                                                                                                                                          | a push that forgets: Back strands focus on `<body>`                                                                                                     |
+| FE text field / checkbox / slider    | `ui/Input` · `Textarea` · `InnerInput` in a `fieldClass` frame · `Checkbox`/`CheckRow` · `Slider`                                                                                                 | a raw `<input>`/`<textarea>` anywhere but those primitives (lint-enforced)                                                                              |
+| FE glass surface                     | a role: `SURFACE.panel` / `card` / `menu` / `popover` / `tooltip` (`ui/surfaces.ts`)                                                                                                              | a bare `glass`/`glass-card`/`glass-menu` beside a hand-picked radius (lint-enforced)                                                                    |
+| FE static label / button-like link   | `Badge` (flat, no edge) · `LinkButton` / `IconLink`                                                                                                                                               | a glass pill that reads as a chip; an `<a>` hand-painted like a button                                                                                  |
+| FE control                           | `SegmentedToggle`; a long or user's list: `FilterSelect`                                                                                                                                          | a native `<select>` (lint-enforced)                                                                                                                     |
+| FE loading/empty/error               | `QueryState` / `StateMessage`                                                                                                                                                                     | ad-hoc conditionals                                                                                                                                     |
+| FE failed write                      | `meta.failTitle`, else `notifyActionError(err, title)`                                                                                                                                            | a bare `catch {}` or `notify()` with no error attached                                                                                                  |
+| FE network call                      | `req`/`uploadReq`/`beacon`, or `lib/http.ts` `send` (public pages)                                                                                                                                | a bare `fetch`/`XMLHttpRequest`/`WebSocket` (lint-enforced)                                                                                             |
+| FE diagnostics                       | `lib/log.ts` (`log.info("event.code", msg, attrs)`); a filter change → `lib/filterLog.ts`, a player → `lib/mediaLog.ts`                                                                           | `console.*` (lint-enforced); a value only a higher level may carry, logged unguarded                                                                    |
+| FE state that MIRRORS a prop/query   | derive it, or hold a draft (`draft ?? server`)                                                                                                                                                    | a copy an effect re-syncs — that paints the stale value first                                                                                           |
+| FE state reset on a key change       | adjust it DURING render against a remembered key                                                                                                                                                  | `useEffect(() => setX(init), [key])`                                                                                                                    |
+| FE effect that must not re-subscribe | `useEffectEvent` (React 19.2+); a handler or timer: `useLatest` / `useStableCallback`                                                                                                             | a render-phase `ref.current = x` — the React Compiler skips the component                                                                               |
+| FE hook suppression                  | an inline `eslint-disable-next-line` NAMING the invariant                                                                                                                                         | `eslint-suppressions.json` (deliberately absent — E27 S2)                                                                                               |
+| FE popover / scroll-fade ref         | destructure it: `const { setReference } = pop.refs`, then `ref={setReference}`                                                                                                                    | `ref={pop.refs.setReference}` / `ref={fade.ref}` — the compiler then treats the whole object as a ref and skips                                         |
+| FE async handler with cleanup        | `try { … } catch { … }`, then the cleanup after it (steps that `return` early go in their own function); a conditional, loop or `?.` the `try` needs goes before it or into a module-level helper | `try/finally`, or a `?:` / `??` / loop / `?.` inside `try` — the React Compiler skips the whole component (and `react-hooks/todo` misses most of these) |
 
 ## House rules that bite (learned from real bugs)
 

Dockerfile

@@ -53,8 +53,11 @@ RUN adduser --disabled-password --gecos "" appuser \
 # 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.
+# `apt-get upgrade` (E32): the base image is a snapshot, and the Debian security fixes released since it
+# was cut are only in the archive — the first Trivy scan found one (pcre2) fixed upstream but not in it.
 ARG DENO_VERSION=v2.9.1
 RUN apt-get update \
+    && apt-get upgrade -y --no-install-recommends \
     && 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 \
@@ -78,9 +81,12 @@ RUN printf 'Types: deb\nURIs: http://deb.debian.org/debian\nSuites: bookworm\nCo
 # 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).
+# pip itself is removed once it has installed the lock (E32): nothing runs it at runtime, and it carries
+# its own VENDORED copies of urllib3, msgpack and setuptools, which Trivy reports as the image's own —
+# an attack surface and a CVE stream for a tool the running app never calls.
 COPY backend/requirements.lock .
 RUN --mount=type=cache,target=/root/.cache/pip \
-    pip install --upgrade pip && pip install -r requirements.lock
+    pip install --upgrade pip && pip install -r requirements.lock && pip uninstall -y pip
 
 COPY --chown=appuser backend/ .
 # Read at runtime by config.py as the app_version (a committed single source of truth).

VERSION

@@ -1 +1 @@
-0.98.0
+0.99.0

backend/.basedpyright/baseline.json

@@ -548,64 +548,6 @@
                 }
             }
         ],
-        "./app/plex/stream.py": [
-            {
-                "code": "reportOptionalMemberAccess",
-                "range": {
-                    "startColumn": 51,
-                    "endColumn": 55,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportOptionalMemberAccess",
-                "range": {
-                    "startColumn": 23,
-                    "endColumn": 25,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportOptionalMemberAccess",
-                "range": {
-                    "startColumn": 18,
-                    "endColumn": 31,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportOptionalMemberAccess",
-                "range": {
-                    "startColumn": 75,
-                    "endColumn": 79,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportOptionalMemberAccess",
-                "range": {
-                    "startColumn": 10,
-                    "endColumn": 23,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportOptionalMemberAccess",
-                "range": {
-                    "startColumn": 10,
-                    "endColumn": 12,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportOptionalMemberAccess",
-                "range": {
-                    "startColumn": 10,
-                    "endColumn": 17,
-                    "lineCount": 1
-                }
-            }
-        ],
         "./app/plex/sync.py": [
             {
                 "code": "reportArgumentType",
@@ -638,14 +580,6 @@
                     "endColumn": 89,
                     "lineCount": 1
                 }
-            },
-            {
-                "code": "reportArgumentType",
-                "range": {
-                    "startColumn": 17,
-                    "endColumn": 18,
-                    "lineCount": 1
-                }
             }
         ],
         "./app/plex/tmdb.py": [
@@ -1650,24 +1584,6 @@
                     "endColumn": 36,
                     "lineCount": 1
                 }
-            },
-            {
-                "code": "reportArgumentType",
-                "range": {
-                    "startColumn": 46,
-                    "endColumn": 52,
-                    "lineCount": 1
-                }
-            }
-        ],
-        "./app/youtube/rss.py": [
-            {
-                "code": "reportGeneralTypeIssues",
-                "range": {
-                    "startColumn": 10,
-                    "endColumn": 15,
-                    "lineCount": 1
-                }
             }
         ]
     }

backend/app/README.md

@@ -72,7 +72,9 @@ mutation it records, so an audit entry can never exist without its change (or vi
 ## The gate
 
 Everything below must be green before a change is done (run via `siftlode check`):
-`ruff` (backend) · `tsc` ×3 + `eslint` + `prettier` + `knip` (frontend) · `vitest` · `pytest`. The
-pytest lane runs in `backend/docker-compose.test.yml` — an ephemeral Postgres + the backend tree
-bind-mounted — so the DB-backed integration tests (the `db` fixture) actually run; `SIFTLODE_TEST_
-REQUIRE_DB=1` there turns a would-be silent skip into a hard failure. See `docs/development.md`.
+`ruff` + `basedpyright` (backend) · the lock check + `tsc` ×3 + `eslint` + `prettier` + `knip` +
+`vite build` (frontend) · `vitest` · `pytest`. The pytest lane runs in `backend/docker-compose.test.yml`
+— an ephemeral Postgres + the backend tree bind-mounted — so the DB-backed integration tests (the `db`
+fixture) actually run; a missing database is a hard failure, not a silent skip, unless a hand run asks
+for pure-logic only with `SIFTLODE_TEST_REQUIRE_DB=0`. See `docs/development.md`, and `docs/gates.md`
+for what each gate deliberately leaves out.

backend/app/bodylimit.py

@@ -219,7 +219,7 @@ class BodyLimitMiddleware:
 
         try:
             await self.app(scope, counting_receive, guarded_send)
-        except Exception:  # noqa: BLE001 — only swallowed when WE caused it, see below
+        except Exception:  # only swallowed when WE caused it, see below
             # ClientDisconnect (or whatever a handler raises on a truncated read) is the expected
             # consequence of the disconnect we just faked, and the caller must get the 413 rather
             # than a 500. Anything raised when we did NOT refuse is a real failure and is re-raised

backend/app/downloads/edit.py

@@ -400,7 +400,7 @@ def escalate_kill(proc: subprocess.Popen, terminate, kill, grace_s: float, label
     try:
         proc.wait(timeout=grace_s)
     except subprocess.TimeoutExpired:
-        # noqa TRY400: the exception IS the message here. A TimeoutExpired's traceback is this
+        # TRY400: the exception IS the message here. A TimeoutExpired's traceback is this
         # `wait` call and nothing else — it would add three frames and no fact the line lacks.
         log.error("%s pid %s survived SIGKILL", label, proc.pid)  # noqa: TRY400
 
@@ -456,7 +456,7 @@ def run_ffmpeg(
         try:
             ret = proc.wait(timeout=_FFMPEG_EXIT_GRACE_S)
         except subprocess.TimeoutExpired:  # pipes closed but the process lingers
-            raise StatedFailure("ffmpeg did not exit after closing its output")
+            raise StatedFailure("ffmpeg did not exit after closing its output") from None
     except BaseException:
         # ONE exit path stops the process, so the invariant is unconditional: nothing leaves this
         # function with ffmpeg still running. Not just our own EditAborted/stall — `on_progress`

backend/app/downloads/runner.py

@@ -57,7 +57,7 @@ def main() -> None:
     logs.configure_logging("runner")
     _deprioritize()
     if len(sys.argv) != 2:
-        # noqa T201: a usage line is for the person who typed the command. Logging is already
+        # T201: a usage line is for the person who typed the command. Logging is already
         # configured here, and in a deployment it writes JSON records — the one reader of this
         # line wants the bare sentence, not a record with a request id they do not have.
         print(  # noqa: T201
@@ -104,7 +104,7 @@ def _run(job_id, asset_id, job_kind, source_kind, source_ref, spec, user_id) ->
             else:
                 _download(job_id, asset_id, source_kind, source_ref, spec, user_id)
         except Exception as exc:  # noqa: BLE001 — whatever it is, it is reported here or raw
-            # noqa TRY400: the stack goes with it scrubbed (`scrubbed_stack`); `exc_info` is raw.
+            # TRY400: the stack goes with it scrubbed (`scrubbed_stack`); `exc_info` is raw.
             log.error(  # noqa: TRY400
                 "the download child for job %s failed",
                 job_id,

backend/app/feedquery.py

@@ -106,15 +106,30 @@ def _tag_visible(user: User):
     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]]:
+# The pseudo-category of a selected tag id no Tag row answers (a saved view or the feed state outlives
+# a deleted tag). It filters like a category whose tags no channel carries — to nothing, in the SQL and
+# in feed_summary's mirror alike — instead of the id being dropped, which showed the WHOLE feed under
+# the view's old name (E32 S2). No real category is called this (language/topic/other).
+MISSING_TAG_CATEGORY = "missing"
+
+
+def tags_by_category(db: Session, user: User, 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
-    two can't disagree on which selected tag belongs to which category."""
+    two can't disagree on which selected tag belongs to which category. An unknown id lands in
+    MISSING_TAG_CATEGORY — and so does another user's private tag: resolving it to its real category
+    told the caller which foreign ids exist (E32 review)."""
     if not tag_ids:
         return {}  # skip the pointless `WHERE id IN ()` round-trip on the no-tag-filter hot path
     out: dict[str, list[int]] = {}
-    for tid, cat in db.execute(select(Tag.id, Tag.category).where(Tag.id.in_(tag_ids))).all():
+    visible = or_(Tag.user_id.is_(None), Tag.user_id == user.id)
+    for tid, cat in db.execute(
+        select(Tag.id, Tag.category).where(Tag.id.in_(tag_ids), visible)
+    ).all():
         out.setdefault(cat, []).append(tid)
+    known = {tid for ids in out.values() for tid in ids}
+    if missing := [tid for tid in tag_ids if tid not in known]:
+        out[MISSING_TAG_CATEGORY] = missing
     return out
 
 
@@ -304,7 +319,7 @@ def filtered_query(
         # ALL its selected tags. ⚠️ feed_summary.passes() reimplements this exact rule in Python for the
         # sidebar count/facets — keep the two in lockstep (equivalence-tested by
         # test_feed_summary_matches_count_plus_facets).
-        by_category = tags_by_category(db, tags)
+        by_category = tags_by_category(db, user, tags)
         # Facet counting drops the category being counted so its own chips don't zero each
         # other out (standard drill-down faceting: a category's count ignores its own
         # selections but still honours the other categories' filters).
@@ -395,7 +410,7 @@ def feed_summary(db: Session, user: User, **params) -> dict:
         return {"count": 0, "facets": {}}
 
     # channel -> its visible tag ids, plus each tag's category (for grouping the facet output).
-    visible = or_(ChannelTag.user_id.is_(None), ChannelTag.user_id == user.id)
+    visible = _tag_visible(user)
     channel_tags: dict[str, set[int]] = {}
     tag_category: dict[int, str] = {}
     for cid, tid, cat in db.execute(
@@ -410,7 +425,7 @@ def feed_summary(db: Session, user: User, **params) -> dict:
     # base channel carries still filters everything out for its category — matching the SQL `IN (empty)`
     # behaviour).
     selected_by_cat: dict[str, set[int]] = {
-        cat: set(ids) for cat, ids in tags_by_category(db, params.get("tags") or []).items()
+        cat: set(ids) for cat, ids in tags_by_category(db, user, params.get("tags") or []).items()
     }
 
     def passes(ch_tags: set[int], exclude_cat: str | None) -> bool:
@@ -438,7 +453,7 @@ def feed_summary(db: Session, user: User, **params) -> dict:
         # Drop this category's own selections so its chips keep independent counts; a conjunctive
         # topic-AND keeps them (each remaining chip narrows to channels that ALSO have the selected).
         exclude = None if tag_modes.get(category, "or") == "and" else category
-        for cid, ch_tags in channel_tags.items():
+        for ch_tags in channel_tags.values():
             if not passes(ch_tags, exclude):
                 continue
             for tid in ch_tags:
@@ -671,8 +686,8 @@ def decode_cursor(keys: list[dict], cursor: str) -> tuple[list, str, datetime |
         raw = payload["k"]
         if len(raw) != len(keys):
             raise ValueError("key arity mismatch")
-        vals = [_cursor_dt(v) if k["kind"] == "dt" else v for k, v in zip(keys, raw)]
-        for k, v in zip(keys, vals):
+        vals = [_cursor_dt(v) if k["kind"] == "dt" else v for k, v in zip(keys, raw, strict=True)]
+        for k, v in zip(keys, vals, strict=True):
             if v is None and not k["nullable"]:
                 raise ValueError("null value for a non-nullable key")
         window = payload.get("w")

backend/app/issues/gitea.py

@@ -239,7 +239,7 @@ def deliver(
                 # already open on the tracker and this is what would have recorded its link. We
                 # still must not write — another send owns the row and is opening its own issue —
                 # so say which issue was left behind, because nothing else will.
-                # noqa TRY400: the traceback is one SendClaimLost carrying the session id and
+                # TRY400: the traceback is one SendClaimLost carrying the session id and
                 # nothing else; the issue number below is the whole news.
                 log.error(  # noqa: TRY400
                     "an issue was created by a send that had already lost its claim",

backend/app/logs.py

@@ -166,7 +166,7 @@ def bind(**fields: Any):
     try:
         yield
     finally:
-        for key, token in zip(keys, tokens):
+        for key, token in zip(keys, tokens, strict=True):
             _CONTEXT_VARS[key].reset(token)
 
 

backend/app/main.py

@@ -1,38 +1,36 @@
 import asyncio
 import math
+import mimetypes
 from contextlib import asynccontextmanager, suppress
 from pathlib import Path
 
 from fastapi import FastAPI, HTTPException, Request
 from fastapi.encoders import jsonable_encoder
 from fastapi.exceptions import RequestValidationError
-
-# Logging is configured HERE, before the route modules are imported, so every logger they create at
-# import time is already covered. ONE format for the api, the worker, the download child and alembic
-# alike (app/logs.py) — this replaces the old uvicorn --log-config + the hand-rolled fallback that
-# used to live here, and uvicorn's access log is replaced by the `http.request` middleware below.
-from app import logs
-from app.logs import configure_logging, current_level, log_requests, set_level
-
-configure_logging("api")
-
-log = logs.get_logger(__name__)
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import FileResponse, HTMLResponse, JSONResponse
 from fastapi.staticfiles import StaticFiles
 from sqlalchemy.exc import DataError
 from starlette.middleware.sessions import SessionMiddleware
 
-from app import bodylimit
-from app import collation
-from app import logsink
-from app import state
-from app import sysconfig
-from app.config import settings
-from app.db import SessionLocal, engine
-from app.plex import stream as plex_stream
-from app.plex import subtitles as plex_subtitles
-from app.routes import (
+# Logging is configured HERE, before the app's own modules are imported, so a line one of them logs
+# WHILE importing already has the format (a logger is configured whenever it is created —
+# app/logs.py — but a line emitted before `configure_logging` goes out raw). ONE format for the api,
+# the worker, the download child and alembic alike — this replaces the old uvicorn --log-config +
+# the hand-rolled fallback that used to live here, and uvicorn's access log is replaced by the
+# `http.request` middleware below. The imports after it are E402 on purpose, each one marked.
+from app import logs
+from app.logs import configure_logging, current_level, log_requests, set_level
+
+configure_logging("api")
+
+log = logs.get_logger(__name__)
+from app import bodylimit, collation, logsink, state, sysconfig  # noqa: E402 — logging is configured first
+from app.config import settings  # noqa: E402 — logging is configured first
+from app.db import SessionLocal, engine  # noqa: E402 — logging is configured first
+from app.plex import stream as plex_stream  # noqa: E402 — logging is configured first
+from app.plex import subtitles as plex_subtitles  # noqa: E402 — logging is configured first
+from app.routes import (  # noqa: E402 — logging is configured first
     admin,
     admin_logs as admin_logs_routes,
     audit as audit_routes,
@@ -60,7 +58,7 @@ from app.routes import (
     tags,
     version,
 )
-from app.scheduler import shutdown_scheduler, start_scheduler
+from app.scheduler import shutdown_scheduler, start_scheduler  # noqa: E402 — logging is configured first
 
 
 @asynccontextmanager
@@ -77,7 +75,7 @@ async def lifespan(app: FastAPI):
         # booting — an unreachable or not-yet-migrated database has to start into the env level.
         try:
             set_level(sysconfig.get_str(db, "log_level"))
-        except Exception:  # noqa: BLE001 — any DB/config failure keeps the bootstrap level
+        except Exception:  # any DB/config failure keeps the bootstrap level
             # With the traceback: this catch spans a connection, a query and a coercion at boot,
             # and `%s` of the exception does not say which of them raised.
             log.exception("could not read the stored log level; staying at %s", current_level())
@@ -332,8 +330,6 @@ app.include_router(setup_routes.router)
 
 # Ensure modern image types resolve to the right Content-Type when FileResponse guesses from the
 # filename (the runtime's mimetypes db doesn't always know .webp → it'd fall back to octet-stream).
-import mimetypes
-
 mimetypes.add_type("image/webp", ".webp")
 mimetypes.add_type("image/avif", ".avif")
 

backend/app/models.py

@@ -23,6 +23,7 @@ from sqlalchemy.dialects.postgresql import JSONB, TSVECTOR
 from sqlalchemy.orm import Mapped, mapped_column, relationship, validates
 
 from app.db import Base
+from app.utils import canonical_email
 
 # Every user-supplied display string in this schema shares one width, and it lives HERE so the
 # columns below are declared with it rather than with a literal: a name a person typed goes into
@@ -51,9 +52,6 @@ def display_text(raw: str | None) -> str | None:
     return (raw or "").strip()[:DISPLAY_TEXT_MAX] or None
 
 
-from app.utils import canonical_email
-
-
 # The resume-position columns (VideoState / PlexState.position_seconds) are int4. The checkpoint
 # routes bound their bodies by this, so an out-of-range position is a 422 rather than a 500.
 POSITION_MAX_S = 2**31 - 1

backend/app/plex/client.py

@@ -78,9 +78,10 @@ class PlexClient:
     # --- Catalog mirror (P1) ---
     def section_items(
         self, key: str, item_type: int, start: int = 0, size: int = 200
-    ) -> tuple[list[dict], int]:
+    ) -> tuple[list[dict], int | None]:
         """A page of a section's top-level items. type 1 = movie, 2 = show. Returns
-        (items, total_size)."""
+        (items, total_size); the total is None when the answer carries none, so a container that
+        says "0" (a genuinely empty section) stays distinguishable from one that says nothing."""
         mc = self._get(
             f"/library/sections/{key}/all",
             params={
@@ -93,7 +94,10 @@ class PlexClient:
                 "X-Plex-Container-Size": size,
             },
         )
-        return mc.get("Metadata", []) or [], int(mc.get("totalSize", mc.get("size", 0)) or 0)
+        # `totalSize` only: `size` is THIS page's count, and read as the total it made a single
+        # page look like the whole section — "complete" to a prune or a reconcile (E32 review).
+        total = mc.get("totalSize")
+        return mc.get("Metadata", []) or [], None if total is None else int(total)
 
     def children(self, rating_key: str) -> list[dict]:
         """Direct children (show → seasons, season → episodes)."""
@@ -136,9 +140,14 @@ class PlexClient:
     # --- Collection editing (P2 — write-back to Plex; all shared/global, admin-gated in the routes) ---
     @property
     def machine_id(self) -> str:
-        """Server machineIdentifier — needed in the `uri` of collection add/create calls. Cached."""
+        """Server machineIdentifier — needed in the `uri` of collection add/create calls. Cached.
+        Without one the uri would read `server:///…`, a malformed write Plex answers in its own way;
+        it is refused here, by name (E32 S2)."""
         if not getattr(self, "_machine_id", None):
-            self._machine_id = self._get("/identity").get("machineIdentifier") or ""
+            mid = self._get("/identity").get("machineIdentifier")
+            if not mid:
+                raise PlexError("Plex did not report its machine identifier")
+            self._machine_id = mid
         return self._machine_id
 
     def _write(self, method: str, path: str) -> dict:

backend/app/plex/overlay.py

@@ -0,0 +1,150 @@
+"""The HU overlay: a Hungarian Plex section written onto its English twin's rows (E30), split out of
+`plex/sync.py` (E32 S2), which runs it once per paired section during the full sync.
+
+The pairing is admin-configured (`plex_overlay_map`, ``huKey:enKey,...``). An overlay section creates
+no browsable rows of its own; it only fills the `*_hu` columns of the EN rows it matches by guid.
+`plex/sync.py` and this module import each other as MODULES (attribute access at call time), which is
+what lets either be imported first.
+"""
+
+from collections.abc import Iterable
+
+from sqlalchemy import select
+from sqlalchemy.orm import Session
+
+from app import logs, sysconfig
+from app.models import PlexItem, PlexLibrary, PlexShow
+from app.plex import sync as plex_sync
+from app.plex.client import PlexClient
+from app.plex.genres import hu_genres
+
+log = logs.get_logger(__name__)
+
+
+def overlay_map(db: Session) -> dict[str, str]:
+    """The configured HU-overlay pairing: {huSectionKey: enSectionKey} from `plex_overlay_map`
+    ('huKey:enKey,...'). Each HU section is synced as a non-browsable overlay onto its EN twin.
+    Malformed pairs are skipped."""
+    raw = sysconfig.get_str(db, "plex_overlay_map")
+    out: dict[str, str] = {}
+    for pair in raw.split(","):
+        hu, sep, en = pair.partition(":")
+        hu, en = hu.strip(), en.strip()
+        if sep and hu and en:
+            out[hu] = en
+    return out
+
+
+def sync_overlay(
+    db: Session, plex: PlexClient, lib: PlexLibrary, en_lib_id: int, stats: dict
+) -> None:
+    """Write an overlay section's Hungarian metadata onto its EN twin's rows, matched by guid. Creates
+    NO browsable rows — an overlay library is never listed on its own. Only title/summary/tagline/genres
+    differ by language; the language-neutral people_text feeds both search vectors. A show section's
+    episodes are overlaid too (E30): the HU section lists every episode with its Hungarian title and
+    summary, and the episode rows live in the EN show library.
+
+    This is a full RECONCILE: after a COMPLETE HU listing every guid-bearing EN row's HU fields are
+    cleared, then the matches are repopulated — so an EN row whose HU twin vanished (or was re-guid'd)
+    falls back to EN instead of keeping stale Hungarian metadata. A listing cut short only adds. HU
+    items with no EN match are skipped."""
+    if lib.kind == "movie":
+        passes = [
+            (
+                plex_sync._TYPE_MOVIE,
+                select(PlexItem).where(
+                    PlexItem.library_id == en_lib_id,
+                    PlexItem.kind == "movie",
+                    PlexItem.guid.is_not(None),
+                ),
+            )
+        ]
+    else:
+        passes = [
+            (
+                plex_sync._TYPE_SHOW,
+                select(PlexShow).where(
+                    PlexShow.library_id == en_lib_id, PlexShow.guid.is_not(None)
+                ),
+            ),
+            (
+                plex_sync._TYPE_EPISODE,
+                select(PlexItem).where(
+                    PlexItem.library_id == en_lib_id,
+                    PlexItem.kind == "episode",
+                    PlexItem.guid.is_not(None),
+                ),
+            ),
+        ]
+    for item_type, rows_q in passes:
+        _overlay_pass(db, plex, lib, item_type, db.execute(rows_q).scalars(), stats)
+    db.flush()
+
+
+def _overlay_pass(
+    db: Session,
+    plex: PlexClient,
+    lib: PlexLibrary,
+    item_type: int,
+    rows: Iterable[PlexItem] | Iterable[PlexShow],
+    stats: dict,
+) -> None:
+    """One kind of the overlay (movies, shows or episodes) — see `sync_overlay`."""
+    # guid -> the EN rows carrying it (a list: two editions of one film can share a guid; both overlay).
+    by_guid: dict[str, list[PlexItem | PlexShow]] = {}
+    for r in rows:
+        if r.guid:  # the passes select guid-bearing rows only
+            by_guid.setdefault(r.guid, []).append(r)
+    # The HU listing is read first and applied after, so the clear can wait for its verdict.
+    hu_by_guid, complete = _read_hu_listing(plex, lib, item_type, by_guid)
+    episodes = item_type == plex_sync._TYPE_EPISODE
+    if complete:
+        _clear_hu(by_guid, episodes)
+    else:
+        stats["overlay_incomplete"] = stats.get("overlay_incomplete", 0) + 1
+        log.warning(
+            "the HU listing ended before the server's total; existing HU text is kept",
+            extra=logs.event("plex.sync.overlay_incomplete", library=lib.plex_key),
+        )
+    for g, meta in hu_by_guid.items():
+        targets = by_guid[g]
+        title_hu = (meta.get("title") or "").strip() or None
+        summary_hu = meta.get("summary")
+        tagline_hu = (meta.get("tagline") or "").strip() or None
+        genres_hu = hu_genres(plex_sync._tags(meta, "Genre"))
+        for row in targets:
+            row.title_hu = title_hu
+            row.summary_hu = summary_hu
+            if not episodes:
+                row.tagline_hu = tagline_hu
+                row.genres_hu = genres_hu or row.genres_hu
+        stats["overlaid"] = stats.get("overlaid", 0) + 1
+
+
+def _read_hu_listing(
+    plex: PlexClient, lib: PlexLibrary, item_type: int, by_guid: dict
+) -> tuple[dict[str, dict], bool]:
+    """The HU section's entries for the guids the EN side carries, and whether the walk reached the
+    server's total. The first HU entry for a guid wins; a dup HU item can't overwrite or double-count."""
+    progress: dict = {}
+    hu_by_guid: dict[str, dict] = {}
+    for meta in plex_sync._paginate(plex, lib.plex_key, item_type, progress):
+        g = plex_sync._canonical_guid(meta)
+        if g and g in by_guid and g not in hu_by_guid:
+            hu_by_guid[g] = meta
+    return hu_by_guid, bool(progress.get("complete"))
+
+
+def _clear_hu(by_guid: dict, episodes: bool) -> None:
+    """Reconcile step: clear HU fields on all guid-bearing rows; the matches are re-set after. Only
+    rows that actually held HU data become dirty (SQLAlchemy skips a no-net-change UPDATE), so this is
+    cheap. The genres are the exception: every row gets Hungarian ones, from its HU twin or, lacking
+    one, from its own English list — otherwise the HU genre list mixed "Drama" (no twin) with "Dráma".
+    Only after a COMPLETE listing: one a Plex hiccup cut short would clear the HU text of every title
+    it failed to reach, until the next full sync (E32 S2, the watch reconcile's twin)."""
+    for group in by_guid.values():
+        for row in group:
+            row.title_hu = row.summary_hu = None
+            if not episodes:
+                row.tagline_hu = None
+                row.genres_hu = hu_genres(row.genres)

backend/app/plex/stream.py

@@ -245,6 +245,9 @@ def _probe_video_kind(src: Path) -> str:
             capture_output=True,
             text=True,
             timeout=10,
+            # A non-zero exit is a failed probe (CalledProcessError, a SubprocessError → the branch
+            # below), not an answer: whatever it printed before refusing is not the file's truth.
+            check=True,
         )
     except (subprocess.SubprocessError, OSError) as exc:
         # The safe kind is a real answer, but it is the answer for an 8-bit SDR source — a blind
@@ -502,6 +505,9 @@ def _probe_audio_langs(src: Path) -> list[str]:
             capture_output=True,
             text=True,
             timeout=10,
+            # A non-zero exit is a failed probe (CalledProcessError, a SubprocessError → the branch
+            # below), not an answer: whatever it printed before refusing is not the file's truth.
+            check=True,
         )
         return [ln.strip() for ln in out.stdout.splitlines()]
     except (subprocess.SubprocessError, OSError) as exc:
@@ -615,6 +621,9 @@ def _probe_first_pts(seg: Path) -> float | None:
             capture_output=True,
             text=True,
             timeout=10,
+            # A non-zero exit is a failed probe (CalledProcessError, a SubprocessError → the branch
+            # below), not an answer: whatever it printed before refusing is not the file's truth.
+            check=True,
         )
         for line in out.stdout.splitlines():
             tok = line.strip().strip(",")
@@ -736,8 +745,7 @@ def start_session(
         # 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.
+        # whoever is registered now). The INITIAL spawn never gets None — see its call site.
         # 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
@@ -814,6 +822,7 @@ def start_session(
         return s
 
     s = _spawn(*_select_encode(db, item, transcode, src))
+    assert s is not None  # replace_only=None always supersedes: a seek-restart's last-writer-wins
     # 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)

backend/app/plex/subtitles.py

@@ -162,7 +162,8 @@ def ffmpeg_to_vtt(src: str, sub_ord: int | None) -> str:
         "webvtt",
         "pipe:1",
     ]
-    r = subprocess.run(cmd, capture_output=True, timeout=EXTRACT_TIMEOUT_S)
+    # check=False: the exit status is read on the next line, with ffmpeg's own stderr as the reason.
+    r = subprocess.run(cmd, capture_output=True, timeout=EXTRACT_TIMEOUT_S, check=False)
     if r.returncode != 0 or not r.stdout:
         raise PlexError(
             (r.stderr or b"").decode("utf-8", "replace")[:200] or "ffmpeg subtitle convert failed"

backend/app/plex/sync.py

@@ -15,7 +15,6 @@ dead `enabled` column) is a separate follow-up. Cast + intro/credit markers are
 item-detail/player path (P2), not here.
 """
 
-from collections.abc import Iterable
 from datetime import datetime, timezone
 
 from sqlalchemy import func, select
@@ -23,7 +22,7 @@ from sqlalchemy.orm import Session
 
 from app import logs, sysconfig
 from app.models import PlexCollection, PlexItem, PlexLibrary, PlexSeason, PlexShow
-from app.plex import detail, people
+from app.plex import detail, overlay, people
 from app.plex.client import PlexClient, PlexError, PlexNotConfigured
 from app.plex.genres import hu_genres
 from app.plex.lookups import by_rating_key
@@ -194,20 +193,6 @@ def _enabled_section_keys(db: Session) -> set[str] | None:
     return keys or None
 
 
-def _overlay_map(db: Session) -> dict[str, str]:
-    """The configured HU-overlay pairing: {huSectionKey: enSectionKey} from `plex_overlay_map`
-    ('huKey:enKey,...'). Each HU section is synced as a non-browsable overlay onto its EN twin.
-    Malformed pairs are skipped."""
-    raw = sysconfig.get_str(db, "plex_overlay_map")
-    out: dict[str, str] = {}
-    for pair in raw.split(","):
-        hu, sep, en = pair.partition(":")
-        hu, en = hu.strip(), en.strip()
-        if sep and hu and en:
-            out[hu] = en
-    return out
-
-
 def sync(db: Session) -> dict:
     """Full reconcile of the enabled movie/show sections. Returns a small stats dict."""
     if not sysconfig.get_bool(db, "plex_enabled"):
@@ -223,7 +208,7 @@ def sync(db: Session) -> dict:
         "pruned": 0,
     }
     wanted = _enabled_section_keys(db)
-    overlay_map = _overlay_map(db)  # {huKey: enKey}
+    overlay_map = overlay.overlay_map(db)  # {huKey: enKey}
     overlay_keys = set(overlay_map)
     try:
         with PlexClient(db) as plex:
@@ -267,13 +252,13 @@ def sync(db: Session) -> dict:
                 lib.metadata_lang = "hu"
                 lib.overlay_of = en_lib.id
                 db.flush()
-                _sync_overlay(db, plex, lib, en_lib.id, stats)
+                overlay.sync_overlay(db, plex, lib, en_lib.id, stats)
                 db.commit()
             # Rich-fetch a bounded batch of not-yet-enriched titles' FULL cast, so the whole library
             # becomes filterable over successive runs (the cheap listing above only stored the top ~3).
             try:
                 stats["people_enriched"] = _enrich_people_batch(db, plex)
-            except Exception:  # noqa: BLE001 — best-effort; never fail the sync over a backfill
+            except Exception:  # best-effort; never fail the sync over a backfill
                 # With the traceback: a blind catch over a batch that fetches AND writes can be
                 # a Plex shape change, a DB error or our own bug, and `%s` told them apart badly.
                 log.exception("the Plex people-enrich batch failed")
@@ -282,7 +267,7 @@ def sync(db: Session) -> dict:
             # 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:  # noqa: BLE001 — best-effort; never fail the sync over a backfill
+            except Exception:  # best-effort; never fail the sync over a backfill
                 log.exception("the Plex media-probe batch failed")
     # silent-ok: the return value IS the report. `{"skipped": …}` goes to the scheduler, which
     # logs the job result, and to the admin route, which answers it to the caller.
@@ -296,7 +281,7 @@ def sync(db: Session) -> dict:
     # appear in ANY item's cast/directors — drop those rows, mirroring how Plex drops orphaned metadata.
     try:
         stats["people_pruned"] = people.prune_orphan_people(db)
-    except Exception:  # noqa: BLE001 — best-effort housekeeping; never fail the sync over it
+    except Exception:  # best-effort housekeeping; never fail the sync over it
         log.exception("the Plex people prune failed")
     log.info("Plex sync done: %s", stats)
     return stats
@@ -433,7 +418,10 @@ def _paginate(plex: PlexClient, key: str, item_type: int, progress: dict | None
     if progress is not None:
         # A truthy `total` we reached = a trustworthy complete listing. `total` unknown/zero-with-rows
         # (a Plex that doesn't report totalSize) is treated as NOT complete, so prune stays conservative.
+        # `total` itself is kept for a caller to whom a server that SAID 0 is news it can trust (the
+        # watch reconcile); an empty mirror or overlay must not read it so (E32 S2).
         progress["complete"] = bool(total) and start >= total
+        progress["total"] = total
 
 
 # The section listing exposes at most the top ~20 cast (Plex's own cap); a stored cast longer than this
@@ -661,98 +649,6 @@ def _sync_shows(db: Session, plex: PlexClient, lib: PlexLibrary, stats: dict) ->
     _prune_stale(db, shows, shows_seen, stats, complete=shows_progress.get("complete", False))
 
 
-def _sync_overlay(
-    db: Session, plex: PlexClient, lib: PlexLibrary, en_lib_id: int, stats: dict
-) -> None:
-    """Write an overlay section's Hungarian metadata onto its EN twin's rows, matched by guid. Creates
-    NO browsable rows — an overlay library is never listed on its own. Only title/summary/tagline/genres
-    differ by language; the language-neutral people_text feeds both search vectors. A show section's
-    episodes are overlaid too (E30): the HU section lists every episode with its Hungarian title and
-    summary, and the episode rows live in the EN show library.
-
-    This is a full RECONCILE: every guid-bearing EN row's HU fields are cleared first, then the HU
-    section repopulates the matches — so an EN row whose HU twin vanished (or was re-guid'd) falls back
-    to EN instead of keeping stale Hungarian metadata. HU items with no EN match are skipped."""
-    if lib.kind == "movie":
-        passes = [
-            (
-                _TYPE_MOVIE,
-                select(PlexItem).where(
-                    PlexItem.library_id == en_lib_id,
-                    PlexItem.kind == "movie",
-                    PlexItem.guid.is_not(None),
-                ),
-            )
-        ]
-    else:
-        passes = [
-            (
-                _TYPE_SHOW,
-                select(PlexShow).where(
-                    PlexShow.library_id == en_lib_id, PlexShow.guid.is_not(None)
-                ),
-            ),
-            (
-                _TYPE_EPISODE,
-                select(PlexItem).where(
-                    PlexItem.library_id == en_lib_id,
-                    PlexItem.kind == "episode",
-                    PlexItem.guid.is_not(None),
-                ),
-            ),
-        ]
-    for item_type, rows_q in passes:
-        _overlay_pass(db, plex, lib, item_type, db.execute(rows_q).scalars(), stats)
-    db.flush()
-
-
-def _overlay_pass(
-    db: Session,
-    plex: PlexClient,
-    lib: PlexLibrary,
-    item_type: int,
-    rows: Iterable[PlexItem] | Iterable[PlexShow],
-    stats: dict,
-) -> None:
-    """One kind of the overlay (movies, shows or episodes) — see `_sync_overlay`."""
-    # guid -> the EN rows carrying it (a list: two editions of one film can share a guid; both overlay).
-    by_guid: dict[str, list[PlexItem | PlexShow]] = {}
-    for r in rows:
-        if r.guid:  # the passes select guid-bearing rows only
-            by_guid.setdefault(r.guid, []).append(r)
-    # Reconcile step: clear HU fields on all guid-bearing rows. Only rows that actually held HU data
-    # become dirty (SQLAlchemy skips a no-net-change UPDATE), so this is cheap; matches are re-set below.
-    # The genres are the exception: every row gets Hungarian ones, from its HU twin or, lacking one, from
-    # its own English list — otherwise the HU genre list mixed "Drama" (no twin) with "Dráma".
-    episodes = item_type == _TYPE_EPISODE
-    for group in by_guid.values():
-        for row in group:
-            row.title_hu = row.summary_hu = None
-            if not episodes:
-                row.tagline_hu = None
-                row.genres_hu = hu_genres(row.genres)
-    seen: set[str] = (
-        set()
-    )  # first HU entry for a guid wins; a dup HU item can't overwrite or double-count
-    for meta in _paginate(plex, lib.plex_key, item_type):
-        g = _canonical_guid(meta)
-        targets = by_guid.get(g) if g else None
-        if not targets or g in seen:
-            continue
-        seen.add(g)
-        title_hu = (meta.get("title") or "").strip() or None
-        summary_hu = meta.get("summary")
-        tagline_hu = (meta.get("tagline") or "").strip() or None
-        genres_hu = hu_genres(_tags(meta, "Genre"))
-        for row in targets:
-            row.title_hu = title_hu
-            row.summary_hu = summary_hu
-            if not episodes:
-                row.tagline_hu = tagline_hu
-                row.genres_hu = genres_hu or row.genres_hu
-        stats["overlaid"] = stats.get("overlaid", 0) + 1
-
-
 def _upsert_collection(
     db: Session, existing: PlexCollection | None, rk: str, lib_id: int, meta: dict
 ) -> PlexCollection:
@@ -778,9 +674,11 @@ def resync_collection(db: Session, plex: PlexClient, lib: PlexLibrary, rk: str)
     meta = plex.metadata(rk) or {}
     col = _upsert_collection(db, by_rating_key(db, PlexCollection, rk), rk, lib.id, meta)
     Model = PlexItem if lib.kind == "movie" else PlexShow
-    new_members = {
-        str(c.get("ratingKey")) for c in plex.collection_children(rk) if c.get("ratingKey")
-    }
+    children = _believed_children(plex, rk, meta)
+    if children is None:
+        db.flush()
+        return col
+    new_members = {str(c.get("ratingKey")) for c in children if c.get("ratingKey")}
     current = db.execute(select(Model).where(Model.collection_keys.contains([rk]))).scalars().all()
     for row in current:  # drop rk from rows that are no longer members
         if row.rating_key not in new_members:
@@ -793,6 +691,22 @@ def resync_collection(db: Session, plex: PlexClient, lib: PlexLibrary, rk: str)
     return col
 
 
+def _believed_children(plex: PlexClient, rk: str, meta: dict) -> list[dict] | None:
+    """A collection's members, or None when the answer is not believed: no members from a collection
+    whose own listing counts some (`childCount`) is a glitch, not a collection emptied — the same
+    empty-answer rule as the collection listing's (E32 review). Rebuilding on it showed the
+    collection empty until the next sync."""
+    children = plex.collection_children(rk)
+    count = str(meta.get("childCount") or "0")
+    if children or not count.isdigit() or int(count) == 0:
+        return children
+    log.warning(
+        "Plex listed no members for a non-empty collection; keeping its membership",
+        extra=logs.event("plex.sync.collection_children_empty", collection=rk),
+    )
+    return None
+
+
 def delete_collection_local(db: Session, lib: PlexLibrary, rk: str) -> None:
     """Local cleanup after a collection is deleted from Plex: strip rk from members + drop the row."""
     Model = PlexItem if lib.kind == "movie" else PlexShow
@@ -804,6 +718,19 @@ def delete_collection_local(db: Session, lib: PlexLibrary, rk: str) -> None:
     db.flush()
 
 
+def _rebuild_membership(
+    db: Session, lib: PlexLibrary, membership: dict[str, list[str]], kept: set[str]
+) -> None:
+    """Rebuild collection_keys on every member row of this library (clear + set), carrying over the
+    keys of a collection whose empty answer was not believed (`_believed_children`)."""
+    for Model in (PlexItem, PlexShow):
+        for row in db.execute(select(Model).where(Model.library_id == lib.id)).scalars():
+            held = [k for k in (row.collection_keys or []) if k in kept]
+            keys = [*membership.get(row.rating_key, []), *held]
+            row.collection_keys = list(dict.fromkeys(keys)) or None
+    db.flush()
+
+
 def _sync_collections(db: Session, plex: PlexClient, lib: PlexLibrary, stats: dict) -> None:
     """Mirror a library's collections + membership. Reads never touch Plex afterwards. Membership is
     written as `collection_keys` on member movies (plex_items) / shows (plex_shows). A full reconcile:
@@ -815,7 +742,17 @@ def _sync_collections(db: Session, plex: PlexClient, lib: PlexLibrary, stats: di
             select(PlexCollection).where(PlexCollection.library_id == lib.id)
         ).scalars()
     }
+    if not cols and existing:
+        # The catalog's own rule (see the module doc): an empty listing while we hold rows is a Plex
+        # glitch, not a library emptied of collections. Reconciling on it dropped every collection
+        # (its user-set `editable` flag with it) and every member's keys (E32 S2).
+        log.warning(
+            "Plex listed no collections for a library that has some; keeping them this run",
+            extra=logs.event("plex.sync.collections_empty", library=lib.plex_key),
+        )
+        return
     seen: set[str] = set()
+    kept: set[str] = set()  # collections whose empty children answer is not believed
     membership: dict[str, list[str]] = {}  # member rating_key -> [collection rating_key, ...]
     for meta in cols:
         rk = str(meta.get("ratingKey") or "")
@@ -823,7 +760,10 @@ def _sync_collections(db: Session, plex: PlexClient, lib: PlexLibrary, stats: di
             continue
         _upsert_collection(db, existing.get(rk), rk, lib.id, meta)
         seen.add(rk)
-        for child in plex.collection_children(rk):
+        children = _believed_children(plex, rk, meta)
+        if children is None:
+            kept.add(rk)
+        for child in children or []:
             crk = str(child.get("ratingKey") or "")
             if crk:
                 membership.setdefault(crk, []).append(rk)
@@ -832,9 +772,4 @@ def _sync_collections(db: Session, plex: PlexClient, lib: PlexLibrary, stats: di
     for rk, col in existing.items():
         if rk not in seen:
             db.delete(col)
-    # Rebuild collection_keys on every member row of this library (clear + set).
-    for row in db.execute(select(PlexItem).where(PlexItem.library_id == lib.id)).scalars():
-        row.collection_keys = membership.get(row.rating_key) or None
-    for row in db.execute(select(PlexShow).where(PlexShow.library_id == lib.id)).scalars():
-        row.collection_keys = membership.get(row.rating_key) or None
-    db.flush()
+    _rebuild_membership(db, lib, membership, kept)

backend/app/plex/watch_sync.py

@@ -29,7 +29,7 @@ from sqlalchemy.orm import Session
 
 from app import logs, sysconfig
 from app.db import SessionLocal
-from app.models import PlexItem, PlexLink, PlexState
+from app.models import PlexItem, PlexLibrary, PlexLink, PlexState
 from app.plex.client import PlexClient, PlexError, PlexNotConfigured
 from app.plex.sync import (
     _TYPE_EPISODE,
@@ -72,13 +72,27 @@ def _rk_to_id(db: Session) -> dict[str, int]:
 
 def _scan_plex_states(
     db: Session, plex: PlexClient
-) -> tuple[dict[int, tuple[str, int, datetime | None, datetime | None]], int]:
+) -> tuple[dict[int, tuple[str, int, datetime | None, datetime | None]], int, set[str], set[str]]:
     """Scan the enabled movie/show sections and return ``{item_id: (status, pos, watched_at,
-    prog_at)}`` for every mirrored leaf Plex holds a watch signal for, plus the scanned-leaf count.
-    Shared by the one-time import and the full reconcile (both need Plex's whole current picture)."""
+    prog_at)}`` for every mirrored leaf Plex holds a watch signal for, the scanned-leaf count, the
+    keys of the sections SETTLED — walked to the server's total (or said empty by a server we mirror
+    nothing from) — and the keys of every section walked.
+    Shared by the one-time import and the full reconcile (both need Plex's whole current picture).
+    The settled keys matter to the reconcile alone: it reads "absent from the scan" as "Plex
+    un-watched it", which a walk cut short by a Plex hiccup does not mean (see `_paginate`). Settled
+    is decided PER SECTION: one section that never settles (a library emptied on Plex while its
+    mirrored items are kept) must not stop un-watches syncing in all the others (E32 review)."""
     item_id_by_rk = _rk_to_id(db)
     wanted = _enabled_section_keys(db)
+    # The sections we mirror something from: a total of 0 from one of those contradicts the mirror.
+    mirrored = set(
+        db.execute(
+            select(PlexLibrary.plex_key).join(PlexItem, PlexItem.library_id == PlexLibrary.id)
+        ).scalars()
+    )
     scanned = 0
+    settled: set[str] = set()
+    walked: set[str] = set()
     out: dict[int, tuple[str, int, datetime | None, datetime | None]] = {}
     for s in plex.sections():
         stype = s.get("type")
@@ -88,7 +102,10 @@ def _scan_plex_states(
         if wanted is not None and key not in wanted:
             continue
         item_type = _TYPE_MOVIE if stype == "movie" else _TYPE_EPISODE
-        for meta in _paginate(plex, key, item_type):
+        walked.add(key)
+        progress: dict = {}
+        before = scanned
+        for meta in _paginate(plex, key, item_type, progress):
             scanned += 1
             item_id = item_id_by_rk.get(str(meta.get("ratingKey") or ""))
             if item_id is None:
@@ -98,7 +115,15 @@ def _scan_plex_states(
             )
             if res is not None:
                 out[item_id] = res
-    return out, scanned
+        # A section the server SAYS is empty (total 0, nothing listed) settles too. Believed only for
+        # a section we mirror nothing from: one whose items we hold answering 0 is a Plex that lost
+        # the library for a moment, not one that un-watched all of it (E32 review) — so it is left
+        # unsettled, and its rows are not cleared.
+        listed = scanned > before
+        said_empty = progress.get("total") == 0 and not listed and key not in mirrored
+        if (progress.get("complete") and listed) or said_empty:
+            settled.add(key)
+    return out, scanned, settled, walked
 
 
 def import_owner_watch_state(db: Session, link: PlexLink) -> dict:
@@ -111,7 +136,8 @@ def import_owner_watch_state(db: Session, link: PlexLink) -> dict:
     stats = {"watched": 0, "in_progress": 0, "scanned": 0}
     try:
         with PlexClient(db) as plex:
-            scanned_states, stats["scanned"] = _scan_plex_states(db, plex)
+            # A partial scan is still safe here: the import only ever ADDS what Plex reports.
+            scanned_states, stats["scanned"], _settled, _walked = _scan_plex_states(db, plex)
             # One row per item (keyed by item_id → inherently de-duped) then bulk-UPSERT. An upsert is
             # idempotent AND concurrency-safe: a repeated/overlapping enable (the toggle firing twice
             # while the multi-second import runs) can't raise a duplicate-key error — it re-updates.
@@ -590,6 +616,28 @@ def run_plex_watch_sync(db: Session) -> dict:
     return total
 
 
+def _clear_unwatched(db: Session, user_id: int, plex_states: dict, settled: set[str]) -> int:
+    """Clear the user's rows Plex no longer has a record for — the mirrored ones (Plex un-watched
+    them); hidden and dirty rows stay (a dirty one is re-pushed by `_repush_dirty`). Only rows of the
+    sections the scan SETTLED: a walk a Plex hiccup cut short leaves out rows it merely failed to
+    reach, and clearing those un-watched them here until the next complete run (E32 S2); an item of
+    a library the allowlist leaves out is absent from every scan, and was cleared on every run (E32
+    review)."""
+    n = 0
+    rows = db.execute(
+        select(PlexState)
+        .join(PlexItem, PlexItem.id == PlexState.item_id)
+        .join(PlexLibrary, PlexLibrary.id == PlexItem.library_id)
+        .where(PlexState.user_id == user_id, PlexLibrary.plex_key.in_(settled))
+    )
+    for st in rows.scalars().all():
+        if st.item_id in plex_states or st.status == "hidden" or not st.synced_to_plex:
+            continue
+        db.delete(st)
+        n += 1
+    return n
+
+
 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:
@@ -608,7 +656,7 @@ def run_plex_watch_reconcile(db: Session) -> dict:
         try:
             with PlexClient(db) as plex:
                 _resolve_account_id(db, plex, link)
-                plex_states, scanned = _scan_plex_states(db, plex)
+                plex_states, scanned, settled, walked = _scan_plex_states(db, plex)
                 total["scanned"] += scanned
 
                 for item_id, (status, pos, watched_at, prog_at) in plex_states.items():
@@ -616,18 +664,19 @@ def run_plex_watch_reconcile(db: Session) -> dict:
                     if ch:
                         total["applied"] += 1
 
-                # Siftlode rows Plex no longer has a record for: clear the ones that were mirrored
-                # (Plex un-watched them); leave hidden + dirty (dirty gets re-pushed just below).
-                for st in (
-                    db.execute(select(PlexState).where(PlexState.user_id == link.user_id))
-                    .scalars()
-                    .all()
-                ):
-                    if st.item_id in plex_states or st.status == "hidden":
-                        continue
-                    if st.synced_to_plex:
-                        db.delete(st)
-                        total["cleared"] += 1
+                total["cleared"] += _clear_unwatched(db, link.user_id, plex_states, settled)
+                if unsettled := sorted(walked - settled):
+                    total["incomplete"] = total.get("incomplete", 0) + 1
+                    log.warning(
+                        "Plex sections %s were cut short or answered empty; their rows are not cleared"
+                        " this run",
+                        ", ".join(unsettled),
+                        extra=logs.event(
+                            "plex.watch.reconcile_incomplete",
+                            user_id=link.user_id,
+                            sections=unsettled,
+                        ),
+                    )
 
                 total["repushed"] += _repush_dirty(db, plex, link)
                 link.last_watch_sync_at = datetime.now(timezone.utc)

backend/app/progress.py

@@ -8,7 +8,7 @@ its own thread/context) never cross wires. When no sink is bound (e.g. a manual
 """
 
 import contextvars
-from typing import Callable, Optional
+from typing import Callable, Literal, Optional
 
 Sink = Callable[[int, Optional[int], Optional[str]], None]
 
@@ -48,7 +48,9 @@ class bind:
         self._token = _sink.set(self._sink)
         return self
 
-    def __exit__(self, *exc) -> bool:
+    # Literal[False], not bool: this never swallows the job's exception, and saying so is what lets
+    # a type checker know a name assigned inside `with bind(...)` is bound after it.
+    def __exit__(self, *exc) -> Literal[False]:
         if self._token is not None:
             _sink.reset(self._token)
         return False

backend/app/routes/_common.py

@@ -60,14 +60,17 @@ def owned_or_404(
     return obj
 
 
-def youtube_refusal(exc: Exception) -> HTTPException:
+def youtube_refusal(exc: Exception, *, playlist: bool = False) -> HTTPException:
     """The answer to an action YouTube refused: a 422 whose reason the UI translates
     (`errors.youtube.<reason>`). One definition, because the routes had grown three shapes of it —
     a bare English string quoting the upstream message, a playlist-scoped reason, and nothing at
     all (a raw 500 from the manual syncs). The upstream failure is already logged where it
     happened (`youtube.api.error`). A failure that is not the Data API's (the search scraper's) is
-    YouTube being unavailable to us — the retryable answer."""
-    reason = refusal_reason(exc) if isinstance(exc, YouTubeError) else "unavailable"
+    YouTube being unavailable to us — the retryable answer. `playlist`: the route acts on one
+    playlist the user picked, so a missing playlist is THAT one, gone (`refusal_reason`)."""
+    reason = (
+        refusal_reason(exc, playlist=playlist) if isinstance(exc, YouTubeError) else "unavailable"
+    )
     return HTTPException(status_code=422, detail={"code": "youtube", "reason": reason})
 
 

backend/app/routes/channels.py

@@ -436,7 +436,7 @@ def explore_channel(
                 channel = db.get(Channel, channel_id)
             result = explore_ingest_page(db, yt, channel, page_token)
     except YouTubeError as exc:
-        raise youtube_refusal(exc)
+        raise youtube_refusal(exc) from exc
     return {
         "ok": True,
         "channel_id": channel_id,
@@ -597,7 +597,7 @@ def subscribe(
             if "subscriptionDuplicate" in exc.reason.split(","):
                 yt_sub_id = ""
             else:
-                raise youtube_refusal(exc)
+                raise youtube_refusal(exc) from exc
         # Enrich a stub channel (title/thumbnail/subscriber count) so it shows up properly right
         # away, on BOTH the normal and the desync path — a resurfaced stub still needs metadata to
         # render. Keep the client open (we're still inside the `with`); a metadata failure here
@@ -658,7 +658,7 @@ def unsubscribe(
     except YouTubeError as exc:
         # 422 (a real, explainable error → speaking modal), not 502 which the client treats as
         # a transient "connection lost" gateway blip.
-        raise youtube_refusal(exc)
+        raise youtube_refusal(exc) from exc
     db.delete(sub)
     db.commit()
     return {"ok": True, "unsubscribed": channel_id}

backend/app/routes/discover.py

@@ -170,7 +170,7 @@ def add_pin(
             # between `resolve_ref` confirming it and this INSERT (a Plex sync dropping a removed
             # item), which trips the FK. Semantically that is the same "no such thing" the pre-check
             # returns above — re-raising handed the user a 500 they could do nothing with.
-            raise not_found("item")
+            raise not_found("item") from None
         return {"ok": True, "id": winner.id, "created": False}
     return {"ok": True, "id": pin.id, "created": True}
 

backend/app/routes/downloads.py

@@ -322,7 +322,7 @@ def set_credential(
     try:
         cleaned = dlcreds.validate_cookies(body.cookies)
     except dlcreds.InvalidCookies as e:
-        raise HTTPException(status_code=400, detail={"code": "cookies", "reason": str(e)})
+        raise HTTPException(status_code=400, detail={"code": "cookies", "reason": str(e)}) from e
     dlcreds.upsert_credential(db, user.id, host_key, cleaned)
     audit.record(
         db,
@@ -407,7 +407,7 @@ def enqueue_download(
     try:
         job = service.enqueue(db, user.id, source_kind, source_ref, spec, profile_id, display_name)
     except quota.QuotaExceeded as e:
-        raise HTTPException(status_code=422, detail=_quota_detail(e))
+        raise HTTPException(status_code=422, detail=_quota_detail(e)) from e
     return _serialize_job(db, job)
 
 
@@ -520,7 +520,7 @@ def upload_download(
             display_name=upload.display_name,
         )
     except quota.QuotaExceeded as e:
-        raise HTTPException(status_code=422, detail=_quota_detail(e))
+        raise HTTPException(status_code=422, detail=_quota_detail(e)) from e
     return _serialize_job(db, job)
 
 
@@ -547,9 +547,9 @@ def enqueue_edit(
     try:
         job = service.enqueue_edit(db, user.id, source_job, spec, display_name)
     except quota.QuotaExceeded as e:
-        raise HTTPException(status_code=422, detail=_quota_detail(e))
+        raise HTTPException(status_code=422, detail=_quota_detail(e)) from e
     except service.EditError as e:
-        raise HTTPException(status_code=400, detail={"code": "edit", "reason": e.reason})
+        raise HTTPException(status_code=400, detail={"code": "edit", "reason": e.reason}) from e
     return _serialize_job(db, job)
 
 

backend/app/routes/feed.py

@@ -133,7 +133,7 @@ def get_feed(
     # Expose each key column on the row so we can build the next cursor from the last item.
     query = query.add_columns(*[k["expr"].label(f"_k{i}") for i, k in enumerate(keys)])
     if vals is not None:
-        for k, v in zip(keys, vals):
+        for k, v in zip(keys, vals, strict=True):
             k["value"] = v
     if ranked and window is not None:
         rows = windowed_relevance_rows(db, query, keys, window, cursor_id, limit + 1)
@@ -431,7 +431,7 @@ def get_video_detail(
         ):
             items = yt.get_videos([video_id])
     except YouTubeError as exc:
-        raise youtube_refusal(exc)
+        raise youtube_refusal(exc) from exc
     if not items:
         raise not_found("video")
 

backend/app/routes/playlists.py

@@ -342,7 +342,7 @@ def sync_youtube(
                 return {"ok": True, **pull_user_playlists(db, user)}
         except YouTubeError as exc:
             db.rollback()
-            raise youtube_refusal(exc)
+            raise youtube_refusal(exc) from exc
 
 
 @router.post("/{playlist_id}/revert-youtube")
@@ -369,10 +369,10 @@ def revert_youtube(
             with quota.attribute(user.id, quota.QuotaAction.PLAYLISTS_PULL):
                 return {"ok": True, **repull_playlist(db, user, pl)}
         except PlaylistGone:
-            raise not_found("playlist")
+            raise not_found("playlist") from None
         except YouTubeError as exc:
             db.rollback()
-            raise youtube_refusal(exc)
+            raise youtube_refusal(exc, playlist=True) from exc
 
 
 def _pushable(db: Session, user: User, playlist_id: int) -> Playlist:
@@ -398,7 +398,7 @@ def push_plan(
         with quota.attribute(user.id, quota.QuotaAction.PLAYLISTS_PUSH):
             plan = plan_merge(db, user, pl)
     except YouTubeError as exc:
-        raise youtube_refusal(exc)
+        raise youtube_refusal(exc, playlist=True) from exc
     plan["remaining_today"] = quota.remaining_today(db)
     plan["affordable"] = plan["units_estimate"] <= plan["remaining_today"]
     return plan
@@ -436,10 +436,10 @@ def push(
                     raise _refused(429, "quota_exceeded")
                 return {"ok": True, **merge_playlist(db, user, pl, live=live)}
         except PlaylistGone:
-            raise not_found("playlist")
+            raise not_found("playlist") from None
         except YouTubeError as exc:
             db.rollback()
-            raise youtube_refusal(exc)
+            raise youtube_refusal(exc, playlist=True) from exc
 
 
 @router.get("/{playlist_id}")
@@ -539,7 +539,7 @@ def delete_playlist(
                     with YouTubeClient(db, user) as yt:
                         yt.delete_playlist(pl.yt_playlist_id)
             except YouTubeError as exc:
-                raise youtube_refusal(exc)
+                raise youtube_refusal(exc, playlist=True) from exc
         # The playlist first, as every item write: the cascade deletes the items before the list row.
         lock_playlists(db, pl.id)
         db.delete(pl)  # items cascade

backend/app/routes/plex/collections.py

@@ -428,7 +428,7 @@ def create_collection(
         db.commit()
     except (PlexError, PlexNotConfigured) as e:
         db.rollback()
-        raise _write_or_pending_error(wrote, e)
+        raise _write_or_pending_error(wrote, e) from e
     return _collection_card(col)
 
 
@@ -450,7 +450,7 @@ def collection_add_item(
         db.commit()
     except (PlexError, PlexNotConfigured) as e:
         db.rollback()
-        raise _write_or_pending_error(wrote, e)
+        raise _write_or_pending_error(wrote, e) from e
     return _collection_card(col)
 
 
@@ -472,7 +472,7 @@ def collection_remove_item(
         db.commit()
     except (PlexError, PlexNotConfigured) as e:
         db.rollback()
-        raise _write_or_pending_error(wrote, e)
+        raise _write_or_pending_error(wrote, e) from e
     return _collection_card(col)
 
 
@@ -502,7 +502,7 @@ def collection_rename(
         db.commit()
     except (PlexError, PlexNotConfigured) as e:
         db.rollback()
-        raise _write_or_pending_error(wrote, e)
+        raise _write_or_pending_error(wrote, e) from e
     return _collection_card(col)
 
 

backend/app/routes/plex/discover.py

@@ -124,8 +124,14 @@ def _recently_added(
     # share one), so the merge doesn't depend on object identity staying alive.
     top_movies = [o for _, kind, o in top if kind == "movie"]
     top_shows = [o for _, kind, o in top if kind == "show"]
-    mcards = {m.rating_key: c for m, c in zip(top_movies, _movie_cards(db, uid, top_movies, lang))}
-    scards = {s.rating_key: c for s, c in zip(top_shows, _show_cards(db, uid, top_shows, lang))}
+    mcards = {
+        m.rating_key: c
+        for m, c in zip(top_movies, _movie_cards(db, uid, top_movies, lang), strict=True)
+    }
+    scards = {
+        s.rating_key: c
+        for s, c in zip(top_shows, _show_cards(db, uid, top_shows, lang), strict=True)
+    }
     return [mcards[o.rating_key] if kind == "movie" else scards[o.rating_key] for _, kind, o in top]
 
 
@@ -351,10 +357,12 @@ def _because_you_watched(
     ordered_shows = [shows[rk] for rk in rks if rk in shows]
     # rating_key is globally unique in Plex, so it keys the serialized cards back safely (no id()).
     mcards = {
-        m.rating_key: c for m, c in zip(ordered_movies, _movie_cards(db, uid, ordered_movies, lang))
+        m.rating_key: c
+        for m, c in zip(ordered_movies, _movie_cards(db, uid, ordered_movies, lang), strict=True)
     }
     scards = {
-        s.rating_key: c for s, c in zip(ordered_shows, _show_cards(db, uid, ordered_shows, lang))
+        s.rating_key: c
+        for s, c in zip(ordered_shows, _show_cards(db, uid, ordered_shows, lang), strict=True)
     }
     items: list[dict] = []
     for rk in rks:

backend/app/routes/saved_views.py

@@ -1,5 +1,5 @@
 from fastapi import APIRouter, Depends
-from pydantic import BaseModel
+from pydantic import BaseModel, field_validator
 from sqlalchemy import func, select, update
 from sqlalchemy.exc import IntegrityError
 from sqlalchemy.orm import Session
@@ -53,11 +53,30 @@ def list_views(
     return [_serialize(v) for v in rows]
 
 
+# A feed view's tag pick is read by more than the feed: the autotag job keeps every tag a view names
+# (sync/autotag.py). Held here to the shape the feed sends — a list of tag ids, at most this many — so
+# a hand-made body (`"tags": 5`, or 60k ids) can't break that job for every user (E32 review).
+_MAX_VIEW_TAGS = 500
+
+
+def _check_filters(filters: dict | None) -> dict | None:
+    tags = (filters or {}).get("tags")
+    if tags is None:
+        return filters
+    if not isinstance(tags, list) or len(tags) > _MAX_VIEW_TAGS:
+        raise ValueError(f"filters.tags must be a list of at most {_MAX_VIEW_TAGS} tag ids")
+    if any(type(t) is not int for t in tags):  # `type`, not isinstance: True is not a tag id
+        raise ValueError("filters.tags must hold tag ids")
+    return filters
+
+
 class CreateViewIn(BaseModel):
     name: str
     filters: dict
     source: str = "feed"
 
+    _filters = field_validator("filters")(_check_filters)
+
 
 @router.post("")
 def create_view(
@@ -87,7 +106,7 @@ def create_view(
         db.commit()
     except IntegrityError:
         db.rollback()
-        raise refused(409, "view_name_taken", name=name)
+        raise refused(409, "view_name_taken", name=name) from None
     return _serialize(view)
 
 
@@ -98,6 +117,8 @@ class UpdateViewIn(BaseModel):
     filters: dict | None = None
     is_default: bool | None = None
 
+    _filters = field_validator("filters")(_check_filters)
+
 
 @router.patch("/{view_id}")
 def update_view(
@@ -135,7 +156,7 @@ def update_view(
         db.commit()
     except IntegrityError:
         db.rollback()
-        raise refused(409, "view_name_taken", name=view.name)
+        raise refused(409, "view_name_taken", name=view.name) from None
     return _serialize(view)
 
 

backend/app/routes/scheduler.py

@@ -74,7 +74,7 @@ def run_job_now(
     try:
         result = trigger_job(job_id, actor_id=user.id)
     except KeyError:
-        raise not_found("job")
+        raise not_found("job") from None
     if result == "already_running":
         raise refused(409, "job_running")
     return {"ok": True, "id": job_id, "started": True}

backend/app/routes/search.py

@@ -331,7 +331,7 @@ def search_youtube(
             # bare 500 hidden behind the FE's generic "search failed" (same rationale as B-core-1).
             try:
                 collected.extend(_ingest_candidates(db, yt, user, candidates))
-            except Exception as exc:  # noqa: BLE001 — any ingest failure, not just YouTubeError
+            except Exception as exc:  # any ingest failure, not just YouTubeError
                 db.rollback()
                 # The term is NOT in this line. A search string is exactly what the privacy
                 # policy keeps out of the log unless the user turned Teljes/TRACE on for

backend/app/routes/sync.py

@@ -39,7 +39,7 @@ def sync_subscriptions(user: User = Depends(require_human), db: Session = Depend
         # The onboarding wizard's first call: an unguarded failure here was a raw 500 and the
         # blocking "Server error" dialog, with nothing the user could act on (E9 F1).
         db.rollback()
-        raise youtube_refusal(exc)
+        raise youtube_refusal(exc) from exc
     result["quota_used_estimate"] = m.used
     result["quota_remaining_today"] = m.remaining
     return {"ok": True, **result}

backend/app/routes/tags.py

@@ -75,7 +75,7 @@ def create_tag(
         db.commit()
     except IntegrityError:
         db.rollback()
-        raise refused(409, "tag_name_taken", name=name)
+        raise refused(409, "tag_name_taken", name=name) from None
     return {
         "ok": True,
         "id": tag.id,
@@ -113,7 +113,7 @@ def update_tag(
         db.commit()
     except IntegrityError:
         db.rollback()
-        raise refused(409, "tag_name_taken", name=tag.name)
+        raise refused(409, "tag_name_taken", name=tag.name) from None
     return {
         "ok": True,
         "id": tag.id,

backend/app/sync/autotag.py

@@ -12,7 +12,7 @@ from sqlalchemy import and_, exists, func, select
 from sqlalchemy.orm import Session
 
 from app import logs, progress, sysconfig
-from app.models import Channel, ChannelTag, Tag, Video
+from app.models import Channel, ChannelTag, SavedView, Tag, Video
 
 log = logs.get_logger(__name__)
 
@@ -288,18 +288,35 @@ def run_autotag_all(db: Session, only_missing: bool = False) -> dict:
     return {"channels_tagged": tagged, "orphan_tags_removed": removed}
 
 
+def _view_tag_ids(filters: object) -> list[int]:
+    """The tag ids a stored view's filters name; anything else in that slot names none."""
+    tags = filters.get("tags") if isinstance(filters, dict) else None
+    if not isinstance(tags, list):
+        return []
+    return [t for t in tags if type(t) is int]  # `type`, not isinstance: True is not a tag id
+
+
 def _cleanup_orphan_system_tags(db: Session) -> int:
-    """Delete system tags that no longer link to any channel (e.g. after a mapping change)."""
-    orphans = (
-        db.execute(
-            select(Tag).where(
-                Tag.user_id.is_(None),
-                ~exists().where(ChannelTag.tag_id == Tag.id),
-            )
-        )
-        .scalars()
-        .all()
-    )
+    """Delete system tags that no longer link to any channel (e.g. after a mapping change) — but not
+    one a saved feed view filters on. Views hold tag IDS, and a deleted tag comes back under a new id
+    when a channel earns it again, so the view's filter would point at nothing; the feed drops an
+    unknown id, and the view showed the whole feed under its old name (E32 S2).
+
+    The views are read defensively, and the kept ids are filtered here rather than in SQL: a view
+    stored before its route checked the shape (or written around it) must not raise for everyone's
+    job, nor push a `NOT IN` past the driver's bind-parameter limit (E32 review)."""
+    in_views = {
+        t
+        for (filters,) in db.execute(select(SavedView.filters).where(SavedView.source == "feed"))
+        for t in _view_tag_ids(filters)
+    }
+    orphans = [
+        tag
+        for tag in db.execute(
+            select(Tag).where(Tag.user_id.is_(None), ~exists().where(ChannelTag.tag_id == Tag.id))
+        ).scalars()
+        if tag.id not in in_views
+    ]
     for tag in orphans:
         db.delete(tag)
     db.commit()

backend/app/sync/explore.py

@@ -25,7 +25,7 @@ from app.models import (
 )
 from app.sync.videos import insert_stubs, stub_from_playlist_item, apply_video_details
 from app.utils import now_utc as _now
-from app.youtube.client import YouTubeClient
+from app.youtube.client import YouTubeClient, YouTubeError, is_playlist_gone
 
 log = logs.get_logger(__name__)
 
@@ -81,7 +81,15 @@ def explore_ingest_page(
     the organic deep backfill) is never touched."""
     if not channel.uploads_playlist_id:
         return {"ingested": 0, "next_page_token": None}
-    data = yt.get_playlist_items(channel.uploads_playlist_id, page_token)
+    try:
+        data = yt.get_playlist_items(channel.uploads_playlist_id, page_token)
+    except YouTubeError as exc:
+        # A channel with no uploads has an uploads id that YouTube answers as not found: an empty
+        # back-catalogue, not a failure (and not a "playlist gone" — the user picked a channel).
+        if not is_playlist_gone(exc):
+            raise
+        log.info("explore ingest channel=%s has no uploads playlist", channel.id)
+        return {"ingested": 0, "next_page_token": None}
     stubs: list[dict] = []
     for item in data.get("items", []):
         stub = stub_from_playlist_item(item, channel.id)

backend/app/sync/maintenance.py

@@ -20,9 +20,9 @@ Quota: phase 1 costs ~(flagged / 50) units, phase 2 ~(batch / 50). Both respect
 backfill reserve as the other jobs so interactive syncs never starve.
 """
 
-from datetime import timedelta
+from datetime import datetime, timedelta
 
-from sqlalchemy import select
+from sqlalchemy import or_, select
 from sqlalchemy.orm import Session
 
 from app import logs, progress, quota, sysconfig
@@ -129,14 +129,14 @@ def _notify_removed(db: Session, impact: dict[int, list[dict]]) -> int:
     return len(impact)
 
 
-def _recheck_flagged(db: Session, yt: YouTubeClient) -> dict:
-    """Phase 1: recover or hard-delete videos already flagged unavailable."""
+def _recheck_flagged(db: Session, yt: YouTubeClient, now: datetime) -> dict:
+    """Phase 1: recover or hard-delete videos already flagged unavailable. `now` is the run's:
+    phase 2 skips a video stamped with it, so one recovered here is not fetched again."""
     flagged = db.execute(select(Video).where(Video.unavailable_since.is_not(None))).scalars().all()
     if not flagged:
         return {"checked": 0, "recovered": 0, "deleted": 0, "notified": 0}
     progress.report(0, len(flagged), "recheck")
     items = {it["id"]: it for it in yt.get_videos([v.id for v in flagged])}
-    now = _now()
     recovered = 0
     to_delete: list[Video] = []
     for video in flagged:
@@ -173,7 +173,7 @@ def _recheck_flagged(db: Session, yt: YouTubeClient) -> dict:
     }
 
 
-def _revalidate_rolling(db: Session, yt: YouTubeClient) -> dict:
+def _revalidate_rolling(db: Session, yt: YouTubeClient, now: datetime) -> dict:
     """Phase 2: re-check the least-recently-checked currently-available videos and flag any
     that have become unplayable (hidden immediately; deleted later if they don't recover)."""
     batch = sysconfig.get_int(
@@ -181,7 +181,6 @@ def _revalidate_rolling(db: Session, yt: YouTubeClient) -> dict:
     )  # admin override, else config default
     flagged_new = 0
     checked = 0
-    now = _now()
     # Process in videos.list-sized pages so we commit incrementally and stop on low quota.
     while checked < batch:
         if quota.backfill_reserve_reached():
@@ -190,6 +189,10 @@ def _revalidate_rolling(db: Session, yt: YouTubeClient) -> dict:
             db.execute(
                 select(Video)
                 .where(Video.unavailable_since.is_(None))
+                # Not one this run already checked: with fewer available videos than the batch, the
+                # loop used to wrap around and re-fetch the same ones until `checked` reached the
+                # batch, spending quota on answers it already had (E32 S2).
+                .where(or_(Video.last_checked_at.is_(None), Video.last_checked_at < now))
                 # NULLS FIRST = never-checked first, then least-recently-checked; equivalent to the old
                 # `(last_checked_at IS NULL) DESC, last_checked_at ASC` but in the exact shape of the
                 # partial ix_videos_recheck_order (migration 0069, PERF-18) so it rides that index.
@@ -220,10 +223,13 @@ def run_maintenance(db: Session) -> dict:
     user = get_service_user(db)
     if user is None:
         return {"reason": "no service user"}
+    # One `now` for the whole run: each phase taking its own let a video phase 1 had just recovered
+    # (stamped with phase 1's) pass phase 2's "not checked this run" test and be fetched twice.
+    now = _now()
     with YouTubeClient(db, user) as yt:
-        phase1 = _recheck_flagged(db, yt)
+        phase1 = _recheck_flagged(db, yt, now)
         phase2 = (
-            _revalidate_rolling(db, yt)
+            _revalidate_rolling(db, yt, now)
             if not quota.backfill_reserve_reached()
             else {"checked": 0, "flagged": 0, "skipped": "low quota"}
         )

backend/app/sync/playlist_merge.py

@@ -0,0 +1,89 @@
+"""The 3-way merge of a YouTube-linked playlist, as a pure function: what each side gains and loses
+so neither loses an item, the merged order, and the reorder moves YouTube needs to reach it. No I/O —
+`sync/playlists.py` reads both sides, calls `merge_plan`, and writes the outcome."""
+
+from dataclasses import dataclass
+
+
+def _reorder_moves(current: list[str], desired: list[str]) -> int:
+    """Count the playlistItems.update moves an insertion-sort would need to turn
+    `current` order into `desired` order (both already the same set of video ids).
+    Items already in place are skipped; this matches what apply_push actually executes."""
+    model = list(current)
+    moves = 0
+    for i, want in enumerate(desired):
+        if i < len(model) and model[i] == want:
+            continue
+        j = model.index(want, i)
+        model.pop(j)
+        model.insert(i, want)
+        moves += 1
+    return moves
+
+
+@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,
+    )

backend/app/sync/playlists.py

@@ -1,6 +1,7 @@
 """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: two-way sync
-local edits with YouTube (`plan_merge` / `merge_playlist`), behind the optional write scope.
+local edits with YouTube (`plan_merge` / `merge_playlist`), behind the optional write scope; the
+pure 3-way merge they run is `sync/playlist_merge.py`.
 
 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
@@ -10,7 +11,7 @@ import hashlib
 import json
 from collections.abc import Callable, Iterator
 from contextlib import AbstractContextManager, contextmanager
-from dataclasses import dataclass
+
 from datetime import datetime, timezone
 from typing import TypeVar
 
@@ -21,9 +22,11 @@ from sqlalchemy.pool import NullPool
 from app import logs, progress, quota
 from app.auth import has_read_scope
 from app.models import Channel, Playlist, PlaylistItem, User, Video
+from app.sync.playlist_merge import merge_plan
 from app.sync.runner import token_users
+from app.sync.subscriptions import blank_listing, refuse_blank_listing, vanished
 from app.sync.videos import apply_video_details, parse_dt
-from app.youtube.client import YouTubeClient, YouTubeError
+from app.youtube.client import YouTubeClient, YouTubeError, is_playlist_gone
 
 log = logs.get_logger(__name__)
 # Cost of a single YouTube write op (playlists/playlistItems insert/update/delete).
@@ -316,6 +319,24 @@ def user_sync_claim(db: Session, user_id: int) -> AbstractContextManager[bool]:
     return _advisory_claim(db, _USER_SYNC_LOCK_NS, user_id)
 
 
+def _mirror_listing(yt: YouTubeClient, ytid: str, count: object, pl_id: int) -> list[str] | None:
+    """A mirror's video ids from YouTube, or None when there is nothing to believe: the list was
+    deleted between the pull's listing and this read (the next pull drops the mirror as vanished —
+    not a reason to fail every other list, E32 review round 2), or YouTube listed no items for a
+    list it counts as non-empty (`blank_listing`)."""
+    try:
+        ids = list(yt.iter_my_playlist_video_ids(ytid))
+    except YouTubeError as exc:
+        if not is_playlist_gone(exc):
+            raise
+        log.info("YouTube playlist of %s vanished mid-pull; skipped", pl_id)
+        return None
+    if blank_listing(ids, count):
+        log.warning("YouTube listed no items for non-empty playlist %s; kept", pl_id)
+        return None
+    return ids
+
+
 def pull_user_playlists(db: Session, user: User) -> dict:
     """The mirror pull itself; the caller holds `user_sync_claim`."""
     synced = 0
@@ -337,12 +358,10 @@ def pull_user_playlists(db: Session, user: User) -> dict:
                     Playlist.source == "local",
                     Playlist.yt_playlist_id.is_not(None),
                 )
-            )
-            .scalars()
-            .all()
+            ).scalars()
         )
-        # Drop mirrors whose YouTube playlist no longer exists — locked first, as every item write.
-        gone = [pl for ytid, pl in existing.items() if ytid not in yt_ids]
+        # Drop vanished mirrors (none on an empty answer) — locked first, as every item write.
+        gone = vanished(existing, yt_ids)
         if gone:
             lock_playlists(db, *(pl.id for pl in gone))
         for pl in gone:
@@ -376,7 +395,10 @@ def pull_user_playlists(db: Session, user: User) -> dict:
                     # The user is pushing or re-pulling this very list: it writes the same rows.
                     # The next scheduled run refreshes it.
                     continue
-                ids = list(yt.iter_my_playlist_video_ids(ytid))
+                ids = _mirror_listing(yt, ytid, p.get("item_count"), pl.id)
+                if ids is None:
+                    db.rollback()  # a mirror this run just created is not kept empty either
+                    continue
                 # Ingest first — it commits — so the row lock below is held from the dirty check
                 # to the commit that replaces the items.
                 _ensure_videos(db, yt, ids)
@@ -408,90 +430,6 @@ def _local_video_ids(db: Session, pl: Playlist) -> list[str]:
     )
 
 
-def _reorder_moves(current: list[str], desired: list[str]) -> int:
-    """Count the playlistItems.update moves an insertion-sort would need to turn
-    `current` order into `desired` order (both already the same set of video ids).
-    Items already in place are skipped; this matches what apply_push actually executes."""
-    model = list(current)
-    moves = 0
-    for i, want in enumerate(desired):
-        if i < len(model) and model[i] == want:
-            continue
-        j = model.index(want, i)
-        model.pop(j)
-        model.insert(i, want)
-        moves += 1
-    return moves
-
-
-@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
@@ -519,6 +457,7 @@ def plan_merge(db: Session, user: User, pl: Playlist, *, live=None) -> dict:
             snippet = yt.get_playlist_snippet(pl.yt_playlist_id)
     rename = bool(snippet) and (snippet.get("title") or "") != pl.name
     yt_ids = [it["video_id"] for it in current]
+    refuse_blank_listing(yt_ids, (snippet or {}).get("item_count"))
     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 {
@@ -665,6 +604,8 @@ def merge_playlist(db: Session, user: User, pl: Playlist, *, live=None) -> dict:
             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]
+        # A merge would read "YouTube lists none of them" as "YouTube deleted them all".
+        refuse_blank_listing(yt_ids, (snippet or {}).get("item_count"))
         # 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`).
@@ -803,8 +744,11 @@ def repull_playlist(db: Session, user: User, pl: Playlist) -> dict:
     with YouTubeClient(db, user) as yt:
         snippet = yt.get_playlist_snippet(pl.yt_playlist_id)
         if snippet is None:
-            raise YouTubeError("Playlist no longer exists on YouTube")
+            raise YouTubeError(
+                "Playlist no longer exists on YouTube", reason="playlistNotFound", path="playlists"
+            )
         ids = list(yt.iter_my_playlist_video_ids(pl.yt_playlist_id))
+        refuse_blank_listing(ids, snippet.get("item_count"))
         _ensure_videos(db, yt, ids)
         _lock_or_gone(db, pl)
         pl.name = snippet.get("title") or pl.name

backend/app/sync/runner.py

@@ -15,8 +15,6 @@ from sqlalchemy import func, or_, select, update
 from sqlalchemy.orm import Session
 
 from app import logs, progress, quota, sysconfig
-
-log = logs.get_logger(__name__)
 from app.db import SessionLocal
 from app.models import Channel, OAuthToken, Subscription, User
 from app.sync.explore import followed_channel
@@ -35,6 +33,8 @@ from app.sync.videos import (
 from app.youtube.client import YouTubeClient, YouTubeError, is_quota_refusal
 from app.youtube.rss import RssError, fetch_channel_feed
 
+log = logs.get_logger(__name__)
+
 # RSS feeds are free and network-bound, so fetch many at once; DB writes stay single-threaded.
 RSS_POLL_WORKERS = 16
 # Failed channels named in a poll's summary warning; the rest are counted by reason.
@@ -267,7 +267,7 @@ def run_feed_fallback(db: Session, channel_ids: list[str]) -> dict[str, int]:
                 channel.feed_fallback_at = datetime.now(timezone.utc)
                 db.add(channel)
                 db.commit()
-            except Exception:  # noqa: BLE001 — one channel must not stop the rest
+            except Exception:  # one channel must not stop the rest
                 db.rollback()
                 log.exception(
                     "Feed fallback could not store channel %s",

backend/app/sync/subscriptions.py

@@ -1,6 +1,6 @@
 """Import the authenticated user's YouTube subscriptions and channel metadata."""
 
-from collections.abc import Iterable
+from collections.abc import Collection, Iterable
 from datetime import datetime, timedelta, timezone
 
 from sqlalchemy import or_, select
@@ -9,7 +9,7 @@ from sqlalchemy.orm import Session
 from app import logs
 from app.models import Channel, Subscription, User
 from app.utils import normalize_description
-from app.youtube.client import YouTubeClient, best_thumbnail
+from app.youtube.client import YouTubeClient, YouTubeError, best_thumbnail
 
 log = logs.get_logger(__name__)
 
@@ -115,10 +115,37 @@ def should_prune(fetched_count: int, existing_count: int) -> bool:
     has — taking each row's `deep_requested` flag with it — in a single run. Someone who genuinely
     unsubscribed from everything simply keeps their rows until a sync that returns something.
 
-    Pure so it can be tested without a database; `import_subscriptions` is the only caller."""
+    Pure so it can be tested without a database; its callers are `import_subscriptions` and, through
+    `vanished`, every mirror that drops what the remote no longer lists."""
     return fetched_count > 0 or existing_count == 0
 
 
+def vanished[K, V](existing: dict[K, V], listed: Collection[K]) -> list[V]:
+    """The local mirrors whose key the remote listing no longer has — none at all when the listing
+    is an empty answer that contradicts them (`should_prune`). The YouTube playlist mirrors use it:
+    without it, one blip dropped every mirror (E32 S2)."""
+    if not should_prune(len(listed), len(existing)):
+        return []
+    return [row for key, row in existing.items() if key not in listed]
+
+
+def blank_listing(listed: Collection, count: object) -> bool:
+    """The same rule one level down: no members from a container whose own listing counts some (a
+    playlist's `itemCount`) is a blip, not a list emptied. Replacing or merging on it deleted every
+    mirrored item and reset the merge baseline (E32 review)."""
+    return not listed and isinstance(count, int) and count > 0
+
+
+def refuse_blank_listing(listed: Collection, count: object) -> None:
+    """`blank_listing` for a user-started pull or push: refused as retryable ("try again")."""
+    if blank_listing(listed, count):
+        raise YouTubeError(
+            "YouTube listed no items for a playlist it counts as non-empty",
+            reason="emptyAnswer",
+            path="playlistItems",
+        )
+
+
 def import_subscriptions(db: Session, user: User) -> dict:
     """Pull all subscriptions for `user`, upsert channels + subscription links, prune
     channels the user has unsubscribed from on YouTube, and fetch channel details for

backend/app/sync/videos.py

@@ -11,12 +11,14 @@ from sqlalchemy import and_, func, or_, select, update
 from sqlalchemy.dialects.postgresql import insert as pg_insert
 from sqlalchemy.orm import Session
 
-from app import progress, quota, sysconfig
+from app import logs, progress, quota, sysconfig
 from app.models import LIVE_OR_UPCOMING, Channel, Video
 from app.titles import normalize_title
-from app.youtube.client import YouTubeClient, best_thumbnail
+from app.youtube.client import YouTubeClient, YouTubeError, best_thumbnail, is_playlist_gone
 from app.youtube.shorts import make_client, probe_is_short
 
+log = logs.get_logger(__name__)
+
 _DURATION_RE = re.compile(r"P(?:(\d+)D)?T(?:(\d+)H)?(?:(\d+)M)?(?:(\d+)S)?", re.IGNORECASE)
 
 
@@ -104,6 +106,20 @@ def stub_from_playlist_item(item: dict, channel_id: str) -> dict | None:
     }
 
 
+def _uploads_page(yt: YouTubeClient, channel_id: str, uploads: str, page_token: str | None) -> dict:
+    """One page of the channel's uploads. YouTube answers the uploads list of a channel with no
+    uploads at all as not found: an empty back-catalogue, so an empty last page — not a failure
+    that left `recent_synced_at` unstamped and charged the channel again on every run (E32 review).
+    Any other failure raises."""
+    try:
+        return yt.get_playlist_items(uploads, page_token)
+    except YouTubeError as exc:
+        if not is_playlist_gone(exc):
+            raise
+        log.info("backfill channel=%s has no uploads playlist", channel_id)
+        return {}
+
+
 def backfill_channel_recent(db: Session, yt: YouTubeClient, channel: Channel) -> int:
     """First pass: newest videos up to the configured count or age cutoff. Records a
     resume cursor for the later deep backfill."""
@@ -121,7 +137,7 @@ def backfill_channel_recent(db: Session, yt: YouTubeClient, channel: Channel) ->
 
     while True:
         page_start = page_token  # token that fetched THIS page (None = first page)
-        data = yt.get_playlist_items(channel.uploads_playlist_id, page_token)
+        data = _uploads_page(yt, channel.id, channel.uploads_playlist_id, page_token)
         stopped_mid_page = False
         for item in data.get("items", []):
             stub = stub_from_playlist_item(item, channel.id)
@@ -175,7 +191,7 @@ def backfill_channel_deep(
     for _ in range(max_pages):
         if quota.backfill_reserve_reached():
             break
-        data = yt.get_playlist_items(channel.uploads_playlist_id, page_token)
+        data = _uploads_page(yt, channel.id, channel.uploads_playlist_id, page_token)
         rows = [
             s
             for s in (stub_from_playlist_item(it, channel.id) for it in data.get("items", []))

backend/app/titles.py

@@ -60,7 +60,6 @@ _SHORT_LOWER = {
     "for",
     "or",
     "vs",
-    "the",
     "és",
     "az",
     "egy",
@@ -120,7 +119,6 @@ _ACRONYMS = {
     "nfl",
     "asmr",
     "pov",
-    "diy",
     "wtf",
     "lol",
     "rtx",

backend/app/worker.py

@@ -25,6 +25,7 @@ import threading
 import time
 from collections.abc import Callable
 from datetime import datetime, timezone
+from functools import partial
 
 from sqlalchemy import text
 
@@ -72,7 +73,7 @@ def _wait_for_schema(timeout: float = 300.0) -> bool:
             with SessionLocal() as db:
                 db.execute(text("SELECT 1 FROM download_jobs LIMIT 1"))
             return True
-        except Exception:  # noqa: BLE001 — table not migrated yet / DB not up yet
+        except Exception:  # table not migrated yet / DB not up yet
             if time.monotonic() > deadline:
                 # The traceback, not `str(exc)[:120]`: this is the last thing the worker says
                 # before it exits, and which driver call failed is the whole question.
@@ -366,7 +367,7 @@ def _run_supervised(job_id: int, asset_id: int) -> None:
 
     try:
         proc = _spawn_download_child(job_id)
-    except Exception:  # noqa: BLE001 — spawn failed; don't leave the asset stuck 'downloading'
+    except Exception:  # spawn failed; don't leave the asset stuck 'downloading'
         log.exception("failed to spawn download child for job %s", job_id)
         _reset_asset_pending(asset_id)
         _requeue_if_running(job_id, None)
@@ -438,7 +439,7 @@ def _run_supervised(job_id: int, asset_id: int) -> None:
                         cause="child_exit",
                         exit_code=proc.returncode,
                     )
-        except Exception:  # noqa: BLE001 — boot recovery is the backstop for a stuck 'running' job
+        except Exception:  # boot recovery is the backstop for a stuck 'running' job
             log.exception("post-exit reconciliation failed for job %s", job_id)
         return
 
@@ -501,6 +502,7 @@ def _process_job(job_id: int) -> None:
     then run in a supervised CHILD PROCESS (`_run_supervised`) so a wedged yt-dlp/ffmpeg can be
     hard-killed — a worker THREAD cannot be killed, nor (when it spins in a C call) even
     cooperatively cancelled, and one such thread starves the others via the GIL."""
+    diagnosis = None  # set exactly when the asset has already failed (asset_status == "error")
     with SessionLocal() as db:
         job = db.get(DownloadJob, job_id)
         if job is None:
@@ -528,7 +530,7 @@ def _process_job(job_id: int) -> None:
     if asset_status == "ready":
         _finish_from_cache(job_id, asset_id)
         return
-    if asset_status == "error":
+    if diagnosis is not None:
         _fail_running(
             job_id,
             error=asset_error or "Download failed",
@@ -577,7 +579,7 @@ def _worker_loop(idx: int) -> None:
     while not _stop.is_set():
         try:
             job_id = _claim_job()
-        except Exception:  # noqa: BLE001
+        except Exception:
             log.exception("claim failed")
             _stop.wait(settings.download_poll_seconds)
             continue
@@ -597,12 +599,12 @@ def _worker_loop(idx: int) -> None:
                         job_id,
                         exc,
                         "crash",
-                        lambda: _fail_running(job_id, error="Worker error", error_code=None),
+                        partial(_fail_running, job_id, error="Worker error", error_code=None),
                     )
                 # silent-ok: not silent — `_report_worker_error` logged the crash before this
                 # re-raise. Failing the job hit the database, and letting that out would end this
                 # worker thread for good; boot recovery settles a job left `running`.
-                except Exception:  # noqa: BLE001
+                except Exception:
                     log.exception(
                         "could not fail job %s after its crash",
                         job_id,

backend/app/youtube/client.py

@@ -114,18 +114,32 @@ _DEAD_GRANT = "invalid_grant"
 
 # What a refused YouTube action means to the person who asked for it — the three things they can
 # act on differently: wait for tomorrow's budget, reconnect the account, or try again later.
-YouTubeRefusal = Literal["quota", "reconnect", "unavailable"]
+YouTubeRefusal = Literal["quota", "reconnect", "unavailable", "gone"]
 
 
-def refusal_reason(exc: YouTubeError) -> YouTubeRefusal:
+def is_playlist_gone(exc: YouTubeError) -> bool:
+    """Whether YouTube answered that the playlist read or written does not exist. Only the caller
+    knows which playlist that was: a user's list deleted on YouTube, or a channel's uploads list,
+    which YouTube also answers so for a channel with no uploads at all."""
+    return "playlistNotFound" in exc.reason.split(",")
+
+
+def refusal_reason(exc: YouTubeError, *, playlist: bool = False) -> YouTubeRefusal:
     """Sort a failure by what the user can do about it. A dead grant (Google refused the refresh
     with `invalid_grant`, which also drops the grant — see `_drop_dead_grant`) or no usable token at
     all (raised before any endpoint answered, so with no path and no transport reason) means the
     account must be reconnected; retrying cannot help. Any other token-endpoint failure — a 5xx, a
     429, a misconfigured client — leaves the grant as it was: reconnecting would not fix it, and
-    the account would still read as connected, with no connect button to press."""
+    the account would still read as connected, with no connect button to press.
+
+    `playlist`: the action was on ONE playlist the user picked, so a missing playlist is that list,
+    gone (deleted on YouTube) — neither a retry nor a reconnect helps. Anywhere else the playlist
+    is one the user never named (a channel's uploads, one list of a bulk pull), and "this playlist
+    no longer exists" would describe nothing on their screen (E32 review round 2)."""
     if is_quota_refusal(exc):
         return "quota"
+    if playlist and is_playlist_gone(exc):
+        return "gone"
     if exc.path == "oauth2/token":
         return "reconnect" if exc.reason == _DEAD_GRANT else "unavailable"
     if not exc.path and exc.reason != "transport":
@@ -189,7 +203,7 @@ class YouTubeClient:
             return cached
         try:
             refresh = decrypt(tok.refresh_token_enc)
-        except Exception as exc:  # noqa: BLE001 — Fernet InvalidToken (TOKEN_ENCRYPTION_KEY changed)
+        except Exception as exc:  # Fernet InvalidToken (TOKEN_ENCRYPTION_KEY changed)
             # A key mismatch must degrade like any other token problem (caller handles YouTubeError),
             # not surface as a raw 500 on every scheduler job / connect check. (B-core-2)
             raise YouTubeError("Stored OAuth token is unreadable — reconnect your account") from exc
@@ -423,16 +437,22 @@ class YouTubeClient:
         return resp.json() if resp.content else {}
 
     def get_playlist_snippet(self, playlist_id: str) -> dict | None:
-        """The snippet (title/description) of one playlist, or None if it no longer
-        exists. 1 unit (OAuth, so private playlists work)."""
+        """The snippet (title/description) of one playlist plus its `item_count` (what an empty
+        item listing is checked against), or None if it no longer exists. 1 unit (OAuth, so
+        private playlists work)."""
         data = self._get(
             "playlists",
-            {"part": "snippet", "id": playlist_id, "maxResults": 1},
+            {"part": "snippet,contentDetails", "id": playlist_id, "maxResults": 1},
             cost=1,
             allow_key=False,
         )
         items = data.get("items", [])
-        return items[0].get("snippet") if items else None
+        if not items:
+            return None
+        return {
+            **(items[0].get("snippet") or {}),
+            "item_count": items[0].get("contentDetails", {}).get("itemCount"),
+        }
 
     def update_playlist_title(self, playlist_id: str, title: str) -> None:
         """Rename a playlist on YouTube. 50 units."""

backend/app/youtube/rss.py

@@ -40,6 +40,7 @@ class RssError(Exception):
 def _get_feed(channel_id: str) -> bytes:
     """The feed's body, after up to `1 + len(RETRY_DELAYS)` tries; the LAST failure is raised."""
     url = RSS_URL.format(channel_id=channel_id)
+    error: RssError | None = None
     for attempt in range(len(RETRY_DELAYS) + 1):
         if attempt:
             time.sleep(RETRY_DELAYS[attempt - 1])
@@ -60,6 +61,8 @@ def _get_feed(channel_id: str) -> bytes:
         )
         if resp.status_code not in _RETRYABLE_STATUS:
             break
+    if error is None:  # cannot happen: the range above is never empty, and every try records one
+        raise RssError(f"RSS fetch for {channel_id} made no attempt", "transport")
     raise error
 
 

backend/app/youtube/search_scrape.py

@@ -42,6 +42,9 @@ _HEADERS = {
     "Accept-Language": "en-US,en;q=0.9",
 }
 
+# The top-level keys a first page (contents) and a continuation page (onResponseReceivedCommands)
+# put their result list under.
+_RESULT_FRAMES = {"contents", "onResponseReceivedCommands"}
 _KEY_RE = re.compile(r'"INNERTUBE_API_KEY":"([^"]+)"')
 _VER_RE = re.compile(r'"INNERTUBE_CLIENT_VERSION":"([^"]+)"')
 
@@ -65,29 +68,36 @@ def _runs_text(node: dict | None) -> str | None:
 
 
 def _get_config(client: httpx.Client) -> tuple[str, str]:
-    """The current InnerTube (api_key, client_version), cached after the first fetch."""
+    """The current InnerTube (api_key, client_version), cached after the first fetch that FOUND them.
+
+    The fallback pair is never cached: it used to be, so one failed fetch (or a consent page with no
+    keys on it) at the wrong moment pinned every later search to a hard-coded key and version for
+    the life of the process — and when those went stale, search returned nothing, with no error
+    anywhere (E32 S2). Now the next search simply tries the live pair again."""
     global _config
     if _config is not None:
         return _config
     try:
-        resp = client.get(_RESULTS_URL, params={"search_query": "music"})
-        html = resp.text
-        key = _KEY_RE.search(html)
-        ver = _VER_RE.search(html)
-        _config = (
-            key.group(1) if key else _FALLBACK_KEY,
-            ver.group(1) if ver else _FALLBACK_CLIENT_VERSION,
-        )
+        html = client.get(_RESULTS_URL, params={"search_query": "music"}).text
     except httpx.HTTPError as exc:
-        # The fallback pair is CACHED in `_config` for the life of the process, so one failed
-        # fetch at the wrong moment pins every later search to a hard-coded key and version —
-        # and when those go stale, search returns nothing at all, with no error anywhere.
         log.warning(
             "the InnerTube config could not be fetched; falling back to the pinned key",
             extra=logs.event("youtube.scrape.config_fallback", reason=type(exc).__name__),
         )
-        _config = (_FALLBACK_KEY, _FALLBACK_CLIENT_VERSION)
-    return _config
+        return (_FALLBACK_KEY, _FALLBACK_CLIENT_VERSION)
+    key = _KEY_RE.search(html)
+    ver = _VER_RE.search(html)
+    if key and ver:
+        _config = (key.group(1), ver.group(1))
+        return _config
+    log.warning(
+        "the results page carried no InnerTube config; falling back to the pinned key",
+        extra=logs.event("youtube.scrape.config_fallback", reason="not_on_page"),
+    )
+    return (
+        key.group(1) if key else _FALLBACK_KEY,
+        ver.group(1) if ver else _FALLBACK_CLIENT_VERSION,
+    )
 
 
 def _video_item(vr: dict) -> dict | None:
@@ -182,6 +192,10 @@ def search(q: str, continuation: str | None = None) -> dict:
         except ValueError as exc:  # non-JSON body (blocked / consent / captcha)
             raise ScrapeError("InnerTube returned a non-JSON response") from exc
 
+    # Even a search with no results carries its result list's frame. Without one this is not "no
+    # results" but a shape we do not know (YouTube moved, or a block page in JSON) — say so.
+    if not isinstance(data, dict) or not _RESULT_FRAMES & data.keys():
+        raise ScrapeError("InnerTube returned an unexpected shape")
     items: list[dict] = []
     _collect_videos(data, items, set())
     return {"items": items, "next_page_token": _find_continuation(data)}

backend/docker-compose.test.yml

@@ -35,4 +35,9 @@ services:
     volumes:
       - ./:/app
     working_dir: /app
-    command: python -m pytest
+    # The suite, then the coverage total (E32 D4: reported, no threshold). pytest's exit code is the
+    # lane's — the report is printed either way and never decides it.
+    command:
+      - sh
+      - -c
+      - 'python -m pytest --cov=app --cov-report= ; rc=$$?; echo ">> backend coverage (app/) $$(python -m coverage report --format=total)% of lines"; exit $$rc'

backend/pyrightconfig.json

@@ -25,7 +25,7 @@
 {
   "include": ["app", "alembic"],
   "extraPaths": ["."],
-  "typeCheckingMode": "basic",
+  "typeCheckingMode": "standard",
   "pythonVersion": "3.12",
   "pythonPlatform": "Linux"
 }

backend/pytest.ini

@@ -2,7 +2,9 @@
 # Run from backend/ (the image's /app). `pythonpath = .` puts the app package on sys.path so tests
 # import it as `app.*`, matching runtime. Most of the suite is pure-logic; the DB-backed lane opts in
 # via the `db` fixture and runs in the compose test image. `-rs` reports skip REASONS so a silently
-# skipped lane is visible (the compose lane sets SIFTLODE_TEST_REQUIRE_DB=1 to make skips a hard error).
+# skipped lane is visible (and conftest makes a missing DB/ffmpeg a hard error unless
+# SIFTLODE_TEST_REQUIRE_DB=0). `--strict-markers` (E32): a misspelt `@pytest.mark.skipiff` is an error,
+# not an unknown marker that quietly does nothing.
 testpaths = tests
 pythonpath = .
-addopts = -q -rs
+addopts = -q -rs --strict-markers

backend/requirements-dev.txt

@@ -7,7 +7,10 @@
 # basedpyright: the backend type-check lane (E27 S3). Pinned like everything else here — a type
 # checker whose version floats silently changes what "clean" means, and the ratchet baseline it
 # writes is keyed to the diagnostics THIS version produces.
+# pytest-cov: the coverage REPORT the gate prints (E32 D4) — a number to read, deliberately with no
+# threshold; "every regression test seen red" is the bar, not a percentage.
 basedpyright==1.40.1
 pytest==8.4.2
+pytest-cov==7.1.0
 ruff==0.15.21
 httpx2==2.13.0

backend/requirements.lock

@@ -1,7 +1,10 @@
 # Pinned dependency lock for reproducible builds (SEC-5). GENERATED — do not hand-edit.
 # Source of truth is requirements.txt (the floor ranges); regenerate after editing it with:
 #   docker run --rm -v "$PWD":/b python:3.12-slim sh -c 'pip install -q -r /b/requirements.txt && pip freeze --exclude pip --exclude setuptools --exclude wheel' | sort
-# The prod Dockerfile + Dockerfile.test + CI install THIS file; pip-audit scans it in CI.
+# The prod Dockerfile + Dockerfile.test + CI install THIS file; pip-audit scans it in CI (blocking
+# since E32). A security fix may be ONE pin bumped in place instead of a full regeneration, which
+# would move every other package too — then `pip install -r requirements.lock && pip check` must
+# pass. In place so far: urllib3 2.7.0 -> 2.8.0 (PYSEC-2026-4175/4176/4177, E32).
 APScheduler==3.11.3
 Authlib==1.7.2
 Mako==1.4.1
@@ -53,7 +56,7 @@ starlette==1.6.0
 typing-inspection==0.4.4
 typing_extensions==4.16.0
 tzlocal==5.4.4
-urllib3==2.7.0
+urllib3==2.8.0
 uvicorn==0.52.3
 uvloop==0.22.1
 watchfiles==1.2.0

backend/ruff.toml

@@ -1,7 +1,8 @@
 # Ruff config for the Siftlode backend. Keeps ruff's default rule set (E4/E7/E9 + F = the
-# high-signal pyflakes/pycodestyle checks that catch real dead code + bugs), but ignores E402:
-# a handful of modules (e.g. main.py) deliberately run setup — logging config, sys.path — before
-# importing route modules, so "module import not at top of file" is intentional there, not cruft.
+# high-signal pyflakes/pycodestyle checks that catch real dead code + bugs), all of it on. E402 was
+# ignored for main.py's logging setup; the ignore had let 11 incidental late imports in elsewhere
+# (E32 review), so it is on now and main.py marks each deliberate one (`# noqa: E402 — <why>`).
+# `scripts/e2e_seed.py` edits `sys.path` before its imports, which E402 itself allows.
 #
 # line-length 100 (ruff's default is 88): matches the frontend prettier printWidth so both halves of
 # the repo wrap at the same width, and it's the width `ruff format` enforces (gated via
@@ -17,9 +18,10 @@ target-version = "py312"
 #   LOG     — stdlib logging misuse (`.warn()`, a logger built by hand, `exc_info` on `.exception`)
 #   G       — the call's shape: %-style args, never an f-string the level filter cannot skip, and
 #             never `str(exc)` where `exc_info` would carry the traceback
-#   T20     — `print` instead of a log line. Two deliberate ones remain, each with its `# noqa`
-#             and a why: `downloads/runner.py`'s usage line is for whoever typed it, and
-#             `logsink.py` reports the SINK's own failure, which cannot be logged into the sink.
+#   T20     — `print` instead of a log line. Three deliberate ones remain, each with its `# noqa`
+#             and a why: `downloads/runner.py`'s usage line is for whoever typed it, `logsink.py`
+#             reports the SINK's own failure, which cannot be logged into the sink, and
+#             `scripts/e2e_seed.py` prints the seeded ids for the e2e run that reads them.
 #   TRY400  — `.error()` in an `except` where `.exception()` would keep the traceback
 #   TRY401  — the exception spelled into the message AND passed as `exc_info` (it is in both)
 #   S112    — `except: continue`, the silent swallow inside a loop
@@ -29,5 +31,22 @@ target-version = "py312"
 #             nobody to raise to, a best-effort backfill inside a sync) and always worth a sentence.
 # The wider rule these two enforce lives in tests/test_swallowed_exceptions.py: a handler that
 # neither logs nor re-raises says `# silent-ok: <why>`. Ruff sees only the two narrow shapes.
-extend-select = ["LOG", "G", "T20", "TRY400", "TRY401", "S110", "S112", "BLE001"]
-ignore = ["E402"]
+#
+# E32 (gate integrity) added three more, each measured before it went on and with every hit fixed:
+#   RUF100  — a `# noqa` that suppresses nothing. A stale one is a claim with no rule behind it, and
+#             it stays armed for the day the line changes (24 were removed). A comment that merely
+#             explains a noqa below it names the rule as `# TRY400: …`, never `# noqa TRY400`.
+#   PLW1510 — `subprocess.run` without an explicit `check=`. Found the real E32 bug: three ffprobe
+#             probes read the output of a probe that had FAILED and took it for the file's truth.
+#   B       — flake8-bugbear: loop-variable capture, `raise` without `from` inside `except`, a
+#             `zip` that silently truncates (each one is `strict=True` now — the lengths are an
+#             invariant, so a mismatch should be loud). B008 (a call in a default argument) stays ON:
+#             FastAPI's `Depends(...)` / `Query(...)` ARE that shape by design (474 hits, all of
+#             them), so those two are declared immutable below instead of switching the rule off —
+#             any other call in a default still fails.
+extend-select = [
+  "LOG", "G", "T20", "TRY400", "TRY401", "S110", "S112", "BLE001", "RUF100", "PLW1510", "B",
+]
+
+[lint.flake8-bugbear]
+extend-immutable-calls = ["fastapi.Depends", "fastapi.Query"]

backend/tests/conftest.py

@@ -25,7 +25,7 @@ from fastapi.testclient import TestClient
 from sqlalchemy import create_engine, event, text
 from starlette.requests import HTTPConnection
 
-import app.models  # noqa: F401 — register every model on Base.metadata
+import app.models  # register every model on Base.metadata
 import app.state as app_state
 from app import security
 from app.auth import current_user
@@ -37,9 +37,11 @@ from app.models import User
 # Sentinel for "this dependency had no override before the fixture set one" (see override_dep).
 _MISSING = object()
 
-# The compose test lane sets this so a would-be silent skip (no DB, or no ffmpeg) becomes a hard error
-# — the gate must not print green while the DB-backed / ffmpeg tests were quietly not run.
-_REQUIRE_FULL = os.getenv("SIFTLODE_TEST_REQUIRE_DB") == "1"
+# A would-be silent skip (no DB, or no ffmpeg) is a hard error unless the run says otherwise — the
+# suite must not print green while the DB-backed / ffmpeg tests were quietly not run. ON by default
+# since E32: as an opt-in only the compose lane and CI set, a hand-run `pytest` skipped ~60 DB tests
+# and still passed. `SIFTLODE_TEST_REQUIRE_DB=0` is the explicit "pure-logic only" run.
+_REQUIRE_FULL = os.getenv("SIFTLODE_TEST_REQUIRE_DB", "1") != "0"
 
 
 def _db_reachable() -> bool:
@@ -86,19 +88,20 @@ def _truncate_all():
 
 
 def pytest_configure(config):
-    """Fail the whole run — loudly, once — when SIFTLODE_TEST_REQUIRE_DB=1 but the environment can't
-    actually run the full suite. Without this, an unreachable DATABASE_URL or a missing ffmpeg turns
+    """Fail the whole run — loudly, once — when the full suite is required (the default) but the
+    environment can't actually run it. Without this, an unreachable DATABASE_URL or a missing ffmpeg turns
     ~60 DB tests + the poster tests into silent skips and the gate still exits green."""
     if not _REQUIRE_FULL:
         return
     if not _DB_REACHABLE:
         raise pytest.UsageError(
-            "SIFTLODE_TEST_REQUIRE_DB=1 but no Postgres is reachable at the test DATABASE_URL — the "
-            "DB-backed lane would silently skip. Fix the DB wiring or unset the flag."
+            "no Postgres is reachable at the test DATABASE_URL — the DB-backed lane would silently "
+            "skip. Fix the DB wiring, or run the pure-logic tests only with SIFTLODE_TEST_REQUIRE_DB=0."
         )
     if shutil.which("ffmpeg") is None:
         raise pytest.UsageError(
-            "SIFTLODE_TEST_REQUIRE_DB=1 but ffmpeg is missing — the thumbnail/poster tests would skip."
+            "ffmpeg is missing — the thumbnail/poster tests would skip. Install it, or run the "
+            "pure-logic tests only with SIFTLODE_TEST_REQUIRE_DB=0."
         )
 
 

backend/tests/test_abuse_limits.py

@@ -36,9 +36,14 @@ def test_a_public_url_gets_past_the_guard(db, as_user, make_user, monkeypatch):
         "getaddrinfo",
         lambda *a, **kw: [(None, None, None, "", ("93.184.216.34", 0))],
     )
-    r = as_user(user).post("/api/downloads", json={"source": "https://example.com/v"})
-    detail = r.json().get("detail") if r.status_code >= 400 else None
-    assert not (isinstance(detail, dict) and detail.get("code") == "url_blocked")
+    # An inline spec, so nothing ELSE refuses it: without one the request stopped at the
+    # profile lookup (400 no_profile) and "not url_blocked" held for a request the guard never
+    # had to wave through (E32 S2).
+    r = as_user(user).post(
+        "/api/downloads", json={"source": "https://example.com/v", "spec": {"format": "best"}}
+    )
+    assert r.status_code == 200, r.text
+    assert r.json()["status"] == "queued"
 
 
 def test_youtube_sources_never_consult_the_guard(db, as_user, make_user, monkeypatch):
@@ -50,7 +55,13 @@ def test_youtube_sources_never_consult_the_guard(db, as_user, make_user, monkeyp
     user = make_user()
     db.commit()
     monkeypatch.setattr(urlguard.socket, "getaddrinfo", boom)
-    as_user(user).post("/api/downloads", json={"source": "dQw4w9WgXcQ"})
+    # The job must actually be created: a request refused for any other reason would never reach
+    # the guard either, and the test would pass without proving anything (E32 S2).
+    r = as_user(user).post(
+        "/api/downloads", json={"source": "dQw4w9WgXcQ", "spec": {"format": "best"}}
+    )
+    assert r.status_code == 200, r.text
+    assert r.json()["source_kind"] == "youtube"
 
 
 def test_manual_subscription_sync_goes_on_cooldown(db, as_user, make_user, monkeypatch):
@@ -81,8 +92,12 @@ def test_the_cooldown_is_per_user_not_global(db, as_user, make_user, monkeypatch
     monkeypatch.setattr(syncroutes, "import_subscriptions", lambda d, u: {"imported": 0})
 
     ca = as_user(a)
-    for _ in range(4):
-        ca.post("/api/sync/subscriptions")
+    assert [ca.post("/api/sync/subscriptions").status_code for _ in range(4)] == [
+        200,
+        200,
+        200,
+        429,
+    ]
     assert ca.post("/api/sync/subscriptions").status_code == 429
     assert as_user(b).post("/api/sync/subscriptions").status_code == 200
 

backend/tests/test_autotag_orphans.py

@@ -0,0 +1,64 @@
+"""sync/autotag's orphan cleanup (E32 S2: the module was 32% covered).
+
+A system tag no channel carries any more is deleted — unless a saved feed view filters on it. The
+views hold tag ids; a deleted tag returns under a NEW id when a channel earns it again, and the feed
+drops an unknown id, so the view silently showed the whole feed under its old name.
+"""
+
+from sqlalchemy import select
+
+from app.models import Channel, ChannelTag, SavedView, Tag
+from app.sync import autotag
+
+
+def test_an_orphan_system_tag_goes_but_one_a_saved_view_filters_on_stays(db, make_user):
+    user = make_user()
+    used = Tag(user_id=None, name="Gaming", category="topic")
+    orphan = Tag(user_id=None, name="Cooking", category="topic")
+    in_view = Tag(user_id=None, name="Music", category="topic")
+    own = Tag(user_id=user.id, name="Mine", category="other")
+    ch = Channel(id="UC_tags", title="T")
+    db.add_all([used, orphan, in_view, own, ch])
+    db.flush()
+    db.add(ChannelTag(channel_id=ch.id, tag_id=used.id, user_id=None, source="auto"))
+    db.add(
+        SavedView(
+            user_id=user.id, source="feed", name="Music", filters={"tags": [in_view.id], "q": ""}
+        )
+    )
+    # A Plex view's filters are another vocabulary; they must not break the scan.
+    db.add(SavedView(user_id=user.id, source="plex", name="P", filters={"genres": ["Drama"]}))
+    db.commit()
+
+    assert autotag._cleanup_orphan_system_tags(db) == 1
+    db.expire_all()
+    names = set(db.execute(select(Tag.name)).scalars())
+    assert names == {"Gaming", "Music", "Mine"}  # only the unreferenced system orphan went
+
+
+def test_a_malformed_saved_view_cannot_break_the_cleanup(db, make_user):
+    """A view stored around the route's shape check (or before it) must not raise for everyone's job
+    — `"tags": 5` raised TypeError — and `True` is not tag id 1 (E32 review)."""
+    user = make_user()
+    orphan = Tag(user_id=None, name="Cooking", category="topic")
+    db.add(orphan)
+    db.flush()
+    for i, filters in enumerate(
+        ({"tags": 5}, {"tags": [True]}, ["not", "a", "dict"], {"tags": None})
+    ):
+        db.add(SavedView(user_id=user.id, source="feed", name=f"bad{i}", filters=filters))
+    db.commit()
+    assert autotag._cleanup_orphan_system_tags(db) == 1
+    db.expire_all()
+    assert db.execute(select(Tag).where(Tag.name == "Cooking")).first() is None
+
+
+def test_a_view_kept_tag_list_larger_than_a_bind_parameter_limit_still_cleans_up(db, make_user):
+    user = make_user()
+    orphan = Tag(user_id=None, name="Cooking", category="topic")
+    db.add(orphan)
+    db.flush()
+    huge = list(range(10_000_000, 10_070_000))  # past psycopg's 65535 bind parameters
+    db.add(SavedView(user_id=user.id, source="feed", name="huge", filters={"tags": huge}))
+    db.commit()
+    assert autotag._cleanup_orphan_system_tags(db) == 1

backend/tests/test_body_limit.py

@@ -321,7 +321,7 @@ def _body_reading_functions() -> dict[tuple[str, str], dict]:
                 continue
             names = [name for _, name in calls]
             limits = []
-            for node, name in zip([n for n, _ in calls], names):
+            for node, name in zip([n for n, _ in calls], names, strict=True):
                 if name.startswith("request."):
                     limits.append("<no ceiling declared>")
                     continue

backend/tests/test_debug_sessions.py

@@ -151,7 +151,7 @@ def test_nobody_reaches_another_users_session(db, make_user, as_user):
 def test_the_list_is_the_users_own_newest_first(db, make_user, as_user):
     client = as_user(make_user())
     first = _start(client)["id"]
-    client.post(f"/api/debug-sessions/{first}/stop")
+    assert client.post(f"/api/debug-sessions/{first}/stop").status_code == 200
     second = _start(client)["id"]
     assert [s["id"] for s in client.get("/api/debug-sessions").json()["items"]] == [second, first]
 
@@ -199,10 +199,13 @@ def test_an_erased_account_takes_its_sessions_with_it(db, make_user, as_user):
     user = make_user()
     client = as_user(user)
     sid = _start(client)["id"]
-    client.post(
-        f"/api/debug-sessions/{sid}/screenshots",
-        content=_PNG,
-        headers={"content-type": "image/png"},
+    assert (
+        client.post(
+            f"/api/debug-sessions/{sid}/screenshots",
+            content=_PNG,
+            headers={"content-type": "image/png"},
+        ).status_code
+        == 200
     )
     purge_user(db, user, BackgroundTasks())
     assert db.get(DebugSession, sid) is None
@@ -250,7 +253,7 @@ def test_a_request_naming_the_own_open_session_is_tagged_and_raised(gated, db, c
     _signed_in(client, make_user)
     sid = _start(client, "DEBUG")["id"]
     gated.records.clear()
-    client.get("/api/debug-sessions", headers={"x-debug-session": sid})
+    assert client.get("/api/debug-sessions", headers={"x-debug-session": sid}).status_code == 200
     (line,) = _request_lines(gated)
     assert getattr(line, "debug_session_id", None) == sid
     # Raised to the session's level: the line is kept for storage though the user's own is Alap.
@@ -263,7 +266,7 @@ def test_a_header_naming_anything_else_is_ignored_not_refused(gated, db, client,
     db.commit()
     _signed_in(client, make_user)
     own = _start(client)["id"]
-    client.post(f"/api/debug-sessions/{own}/stop")
+    assert client.post(f"/api/debug-sessions/{own}/stop").status_code == 200
     for value in (foreign, own, "not-a-session", "f" * 16, "A" * 16):
         gated.records.clear()
         # Not `/api/me`: a polled route logs at DEBUG, and an un-raised request would drop the very
@@ -280,7 +283,7 @@ def test_a_header_naming_the_own_session_past_its_cap_is_ignored(gated, db, clie
     sid = _start(client)["id"]
     _expire(db, sid)  # past its cap, not yet swept: still open in the table
     gated.records.clear()
-    client.get("/api/debug-sessions", headers={"x-debug-session": sid})
+    assert client.get("/api/debug-sessions", headers={"x-debug-session": sid}).status_code == 200
     (line,) = _request_lines(gated)
     assert getattr(line, "debug_session_id", None) is None
     assert getattr(line, "elevated", False) is False
@@ -616,7 +619,7 @@ def test_a_users_screenshots_are_capped_across_their_sessions(recording, monkeyp
     client, sid = recording
     monkeypatch.setattr(debugsession, "SCREENSHOT_USER_MAX_BYTES", len(_PNG) * 2)
     assert _upload(client, sid, _PNG).status_code == 200
-    client.post(f"/api/debug-sessions/{sid}/stop")
+    assert client.post(f"/api/debug-sessions/{sid}/stop").status_code == 200
     other = _start(client)["id"]
     assert _upload(client, other, _PNG).status_code == 200
     r = _upload(client, other, _PNG)
@@ -631,7 +634,7 @@ def test_new_sessions_are_paced_but_joining_one_is_not(db, make_user, as_user, m
     client = as_user(make_user())
     sid = _start(client)["id"]
     assert _start(client)["id"] == sid  # another tab joining
-    client.post(f"/api/debug-sessions/{sid}/stop")
+    assert client.post(f"/api/debug-sessions/{sid}/stop").status_code == 200
     r = client.post("/api/debug-sessions", json={"level": "DEBUG"})
     assert r.status_code == 429 and r.json()["detail"]["reason"] == "debug_session_rate_limited"
 
@@ -745,9 +748,16 @@ def test_the_export_is_the_saved_draft_the_evidence_and_the_screenshots(db, make
     db.commit()
     _upload(client, sid, _PNG)
     _upload(client, sid, _JPEG)
-    client.put(
-        f"/api/debug-sessions/{sid}/draft",
-        json={"title": "Spinner stays", "body": "It spins.", "excluded": [dropped_web.id, 999999]},
+    assert (
+        client.put(
+            f"/api/debug-sessions/{sid}/draft",
+            json={
+                "title": "Spinner stays",
+                "body": "It spins.",
+                "excluded": [dropped_web.id, 999999],
+            },
+        ).status_code
+        == 200
     )
 
     r = client.get(f"/api/debug-sessions/{sid}/export")
@@ -1144,7 +1154,7 @@ def test_new_issues_are_paced_per_user(gitea_fake, db, make_user, as_user, monke
     first = _start(client)["id"]
     _ready(client, first)
     assert client.post(f"/api/debug-sessions/{first}/issue").status_code == 200
-    client.post(f"/api/debug-sessions/{first}/stop")
+    assert client.post(f"/api/debug-sessions/{first}/stop").status_code == 200
     second = _start(client)["id"]
     _ready(client, second)
     r = client.post(f"/api/debug-sessions/{second}/issue")

backend/tests/test_diagnostics.py

@@ -212,7 +212,12 @@ def test_a_timestamp_outside_the_consent_window_is_clamped(elevated):
     now = datetime.now(timezone.utc)
     future = (now + timedelta(days=365)).isoformat()
     past = (now - timedelta(days=30)).isoformat()
-    client.post("/api/diagnostics/events", json={"events": [_event(ts=future), _event(ts=past)]})
+    assert (
+        client.post(
+            "/api/diagnostics/events", json={"events": [_event(ts=future), _event(ts=past)]}
+        ).status_code
+        == 200
+    )
     late, early = rows()
     assert late.ts <= datetime.now(timezone.utc)
     assert early.ts >= now - timedelta(hours=diagnostics.ELEVATION_HOURS, minutes=1)
@@ -342,15 +347,15 @@ def _app() -> TestClient:
 
 
 def test_the_account_reaches_the_handlers_own_lines(gated):
-    _app().get("/api/thing/41")
+    assert _app().get("/api/thing/41").status_code == 200
     line = next(r for r in gated.records if r.getMessage() == "an ordinary line")
     assert getattr(line, "user_id", None) == 41
 
 
 def test_one_users_elevation_logs_their_requests_in_detail_and_nobody_elses(gated):
     client = _app()
-    client.get("/api/thing/7", params={"level": "DEBUG"})
-    client.get("/api/thing/8")
+    assert client.get("/api/thing/7", params={"level": "DEBUG"}).status_code == 200
+    assert client.get("/api/thing/8").status_code == 200
     detail = [r for r in gated.records if r.getMessage().startswith("detail only")]
     assert [r.user_id for r in detail] == [7]
     assert getattr(detail[0], "elevated", False) is True
@@ -363,9 +368,9 @@ def test_one_users_elevation_logs_their_requests_in_detail_and_nobody_elses(gate
 
 def test_the_root_level_returns_to_the_base_when_the_elevation_ends(gated):
     client = _app()
-    client.get("/api/thing/7", params={"level": "TRACE"})
+    assert client.get("/api/thing/7", params={"level": "TRACE"}).status_code == 200
     assert logging.getLogger().level == logs.TRACE
-    client.get("/api/thing/7")  # the same user, back at the base
+    assert client.get("/api/thing/7").status_code == 200  # the same user, back at the base
     assert logging.getLogger().level == logging.INFO
     logs._track_elevation(9, logging.DEBUG, datetime.now(timezone.utc) - timedelta(seconds=1))
     assert logging.getLogger().level == logging.INFO  # an already-expired one is pruned at once
@@ -373,15 +378,25 @@ def test_the_root_level_returns_to_the_base_when_the_elevation_ends(gated):
 
 def test_the_query_string_is_logged_only_for_a_traced_request_and_redacted(gated):
     client = _app()
-    client.get("/api/thing/7", params={"level": "DEBUG", "q": "lofi"})
-    client.get("/api/thing/7", params={"level": "TRACE", "q": "lofi", "token": "SECRET"})
+    assert client.get("/api/thing/7", params={"level": "DEBUG", "q": "lofi"}).status_code == 200
+    assert (
+        client.get(
+            "/api/thing/7", params={"level": "TRACE", "q": "lofi", "token": "SECRET"}
+        ).status_code
+        == 200
+    )
     lines = [r for r in gated.records if getattr(r, "event", None) == "http.request"]
     assert "query" not in lines[0].attrs
     assert "q=lofi" in lines[1].attrs["query"] and "SECRET" not in lines[1].attrs["query"]
 
 
 def test_an_address_typed_into_a_search_is_redacted_though_the_browser_encodes_it(gated):
-    _app().get("/api/thing/7?level=TRACE&q=someone%40example.com&new_password=hunter2")
+    assert (
+        _app()
+        .get("/api/thing/7?level=TRACE&q=someone%40example.com&new_password=hunter2")
+        .status_code
+        == 200
+    )
     (line,) = [r for r in gated.records if getattr(r, "event", None) == "http.request"]
     assert line.attrs["query"] == "level=TRACE&q=[email]&new_password=[redacted]"
 
@@ -400,7 +415,7 @@ def test_a_credential_param_goes_whole_however_its_value_decodes(raw):
 
 def test_an_admin_level_of_trace_does_not_log_other_users_query_strings(gated):
     logs.set_level("TRACE")
-    _app().get("/api/thing/7", params={"q": "something private"})
+    assert _app().get("/api/thing/7", params={"q": "something private"}).status_code == 200
     (line,) = [r for r in gated.records if getattr(r, "event", None) == "http.request"]
     assert "query" not in line.attrs
 
@@ -488,7 +503,7 @@ def test_a_real_sign_in_carries_the_consented_level_into_the_process(gated, clie
     user = _signed_in(client, make_user)
     assert client.put("/api/me/diagnostics", json={"level": "DEBUG"}).status_code == 200
     logs._elevations.clear()  # only a request resolving the account through auth may put it back
-    client.get("/api/me")
+    assert client.get("/api/me").status_code == 200
     assert logs._elevations[user.id][0] == logging.DEBUG
     assert client.put("/api/me/diagnostics", json={"level": "INFO"}).status_code == 200
     assert user.id not in logs._elevations

backend/tests/test_email_canonical.py

@@ -13,12 +13,12 @@ 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
 
+_UAT_PW = "correct horse battery"
+
 # (input, expected canonical) — the matrix the sprint promised, plus the shapes that must NOT fold.
 CASES = [
     # Gmail: dots and +tags are noise…
@@ -334,7 +334,7 @@ def test_me_reports_the_google_address_only_when_it_differs(client, db, make_use
     )
     assert client.get("/api/me").json()["google_email"] is None
 
-    client.post("/auth/logout")
+    assert client.post("/auth/logout").status_code == 200
     tagged = make_user(email="me+siftlode@gmail.com", password=_UAT_PW)
     tagged.google_email = "me@gmail.com"
     db.commit()

backend/tests/test_empty_listing_guards.py

@@ -0,0 +1,259 @@
+"""An empty answer is not an emptied library (E32 S2).
+
+Every mirror here reconciles: what the remote no longer lists is removed locally. The catalog
+(`_prune_stale`) and the subscriptions (`should_prune`) had long refused to do that on an empty
+listing that contradicts what we hold — a 200 with no items is a blip far more often than a user
+who removed everything. Two mirrors did not: the Plex collections (a row carries the user-set
+`editable` flag, and every member its keys) and the YouTube playlist mirrors. These hold both — and,
+one level down (E32 review), a collection's members and a playlist's items: an empty answer that
+contradicts the remote's own count is not believed either.
+"""
+
+import pytest
+from sqlalchemy import select
+
+from app.models import (
+    Channel,
+    Playlist,
+    PlaylistItem,
+    PlexCollection,
+    PlexItem,
+    PlexLibrary,
+    Video,
+)
+from app.plex import sync as plex_sync
+from app.sync import playlists as plsync
+from app.youtube.client import YouTubeError
+
+
+class _Plex:
+    def __init__(self, collections: list[dict], children: dict[str, list[dict]]):
+        self._collections = collections
+        self._children = children
+
+    def collections(self, section_key):
+        return self._collections
+
+    def collection_children(self, rk):
+        return self._children.get(rk, [])
+
+    def metadata(self, rk):
+        return next((c for c in self._collections if c.get("ratingKey") == rk), {})
+
+
+def _library_with_a_collection(db):
+    lib = PlexLibrary(plex_key="4", title="Movies", kind="movie")
+    db.add(lib)
+    db.flush()
+    db.add(PlexCollection(rating_key="c1", library_id=lib.id, title="Bond", editable=True))
+    movie = PlexItem(
+        rating_key="m1", library_id=lib.id, kind="movie", title="Dr. No", collection_keys=["c1"]
+    )
+    db.add(movie)
+    db.commit()
+    return lib, movie
+
+
+def test_an_empty_collection_listing_keeps_the_collections_and_their_members(db):
+    lib, movie = _library_with_a_collection(db)
+    stats = {"collections": 0}
+    plex_sync._sync_collections(db, _Plex([], {}), lib, stats)
+    db.commit()
+    db.expire_all()
+    col = db.execute(select(PlexCollection).where(PlexCollection.rating_key == "c1")).scalar_one()
+    assert col.editable is True
+    assert db.get(PlexItem, movie.id).collection_keys == ["c1"]
+
+
+def test_a_listing_with_something_in_it_still_prunes_what_it_no_longer_has(db):
+    lib, movie = _library_with_a_collection(db)
+    stats = {"collections": 0}
+    other = {"ratingKey": "c2", "title": "Alien"}
+    plex_sync._sync_collections(db, _Plex([other], {"c2": []}), lib, stats)
+    db.commit()
+    db.expire_all()
+    keys = set(db.execute(select(PlexCollection.rating_key)).scalars())
+    assert keys == {"c2"}
+    assert db.get(PlexItem, movie.id).collection_keys is None
+
+
+def test_no_members_from_a_collection_plex_counts_as_non_empty_keeps_its_members(db):
+    lib, movie = _library_with_a_collection(db)
+    stats = {"collections": 0}
+    bond = {"ratingKey": "c1", "title": "Bond", "childCount": 2}
+    plex_sync._sync_collections(db, _Plex([bond], {"c1": []}), lib, stats)
+    db.commit()
+    db.expire_all()
+    assert db.get(PlexItem, movie.id).collection_keys == ["c1"]
+
+
+def test_a_collection_plex_counts_as_empty_does_lose_its_members(db):
+    lib, movie = _library_with_a_collection(db)
+    stats = {"collections": 0}
+    bond = {"ratingKey": "c1", "title": "Bond", "childCount": 0}
+    plex_sync._sync_collections(db, _Plex([bond], {"c1": []}), lib, stats)
+    db.commit()
+    db.expire_all()
+    assert db.get(PlexItem, movie.id).collection_keys is None
+
+
+@pytest.mark.parametrize(("count", "kept"), [(2, ["c1"]), (0, None)])
+def test_a_collection_resync_believes_an_empty_member_list_only_with_a_zero_count(db, count, kept):
+    lib, movie = _library_with_a_collection(db)
+    bond = {"ratingKey": "c1", "title": "Bond", "childCount": count}
+    plex_sync.resync_collection(db, _Plex([bond], {"c1": []}), lib, "c1")
+    db.commit()
+    db.expire_all()
+    assert db.get(PlexItem, movie.id).collection_keys == kept
+
+
+class _YT:
+    def __init__(self, playlists: list[dict], snippet: dict | None = None):
+        self._playlists = playlists
+        self._snippet = snippet
+
+    def __call__(self, *_):
+        return self
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *_):
+        return False
+
+    def iter_my_playlists(self):
+        return self._playlists
+
+    def iter_playlist_items_with_ids(self, _ytid):
+        return []
+
+    def iter_my_playlist_video_ids(self, _ytid):
+        return []
+
+    def get_playlist_snippet(self, _ytid):
+        return self._snippet
+
+    def get_videos(self, _ids):
+        return []
+
+
+def test_an_empty_playlist_answer_keeps_the_youtube_mirrors(db, make_user, monkeypatch):
+    user = make_user()
+    db.add(Playlist(user_id=user.id, name="Mixes", source="youtube", yt_playlist_id="PL1"))
+    db.commit()
+    monkeypatch.setattr(plsync, "YouTubeClient", _YT([]))
+    plsync.pull_user_playlists(db, user)
+    db.expire_all()
+    names = db.execute(select(Playlist.name).where(Playlist.user_id == user.id)).scalars().all()
+    assert "Mixes" in names
+
+
+def test_a_playlist_answer_with_something_in_it_still_drops_a_vanished_mirror(
+    db, make_user, monkeypatch
+):
+    user = make_user()
+    db.add(Playlist(user_id=user.id, name="Mixes", source="youtube", yt_playlist_id="PL1"))
+    db.commit()
+    monkeypatch.setattr(plsync, "YouTubeClient", _YT([{"id": "PL2", "title": "New"}]))
+    plsync.pull_user_playlists(db, user)
+    db.expire_all()
+    ytids = set(
+        db.execute(select(Playlist.yt_playlist_id).where(Playlist.source == "youtube")).scalars()
+    )
+    assert "PL1" not in ytids
+
+
+class _YTOneGone(_YT):
+    """A list deleted on YouTube between the listing and the read of its items."""
+
+    def iter_my_playlist_video_ids(self, ytid):
+        if ytid == "PLgone":
+            raise YouTubeError("m", reason="playlistNotFound", path="playlistItems")
+        return []
+
+
+def test_a_list_deleted_mid_pull_is_skipped_and_the_rest_still_sync(db, make_user, monkeypatch):
+    # Not "this playlist no longer exists" for a bulk pull the user never named a list in, and not
+    # a failure for every other list either (E32 review round 2): the next pull drops the mirror.
+    user = make_user()
+    db.commit()
+    listing = [
+        {"id": "PLgone", "title": "Gone", "item_count": 3},
+        {"id": "PL2", "title": "Kept", "item_count": 0},
+    ]
+    monkeypatch.setattr(plsync, "YouTubeClient", _YTOneGone(listing))
+    assert plsync.pull_user_playlists(db, user) == {"synced": 1}
+    db.expire_all()
+    ytids = set(
+        db.execute(select(Playlist.yt_playlist_id).where(Playlist.user_id == user.id)).scalars()
+    )
+    assert ytids == {"PL2"}
+
+
+def _mirror_with_an_item(db, user, **kw):
+    db.add(Channel(id="UC_pl", title="C"))
+    db.flush()
+    db.add(Video(id="v1", channel_id="UC_pl", title="One"))
+    pl = Playlist(user_id=user.id, name="Mixes", yt_playlist_id="PL1", **kw)
+    db.add(pl)
+    db.flush()
+    db.add(PlaylistItem(playlist_id=pl.id, video_id="v1", position=0))
+    db.commit()
+    return pl
+
+
+def _items(db, pl):
+    db.expire_all()
+    return (
+        db.execute(select(PlaylistItem.video_id).where(PlaylistItem.playlist_id == pl.id))
+        .scalars()
+        .all()
+    )
+
+
+def test_no_items_from_a_playlist_youtube_counts_as_non_empty_keeps_the_mirror_items(
+    db, make_user, monkeypatch
+):
+    user = make_user()
+    pl = _mirror_with_an_item(db, user, source="youtube")
+    listing = [{"id": "PL1", "title": "Mixes", "item_count": 1}]
+    monkeypatch.setattr(plsync, "YouTubeClient", _YT(listing))
+    plsync.pull_user_playlists(db, user)
+    assert _items(db, pl) == ["v1"]
+
+
+def test_a_playlist_youtube_counts_as_empty_is_emptied(db, make_user, monkeypatch):
+    user = make_user()
+    pl = _mirror_with_an_item(db, user, source="youtube")
+    listing = [{"id": "PL1", "title": "Mixes", "item_count": 0}]
+    monkeypatch.setattr(plsync, "YouTubeClient", _YT(listing))
+    plsync.pull_user_playlists(db, user)
+    assert _items(db, pl) == []
+
+
+def test_a_reset_to_youtube_refuses_a_blank_listing_and_keeps_the_items(db, make_user, monkeypatch):
+    user = make_user()
+    pl = _mirror_with_an_item(db, user, source="youtube")
+    monkeypatch.setattr(plsync, "YouTubeClient", _YT([], {"title": "Mixes", "item_count": 1}))
+    with pytest.raises(YouTubeError) as err:
+        plsync.repull_playlist(db, user, pl)
+    db.rollback()
+    assert err.value.reason == "emptyAnswer"
+    assert _items(db, pl) == ["v1"]
+
+
+def test_a_reset_of_a_deleted_playlist_says_it_is_gone(db, make_user, monkeypatch):
+    user = make_user()
+    pl = _mirror_with_an_item(db, user, source="youtube")
+    monkeypatch.setattr(plsync, "YouTubeClient", _YT([], None))
+    with pytest.raises(YouTubeError) as err:
+        plsync.repull_playlist(db, user, pl)
+    assert err.value.reason == "playlistNotFound"
+
+
+def test_a_push_plan_refuses_a_blank_listing_rather_than_reading_it_as_all_deleted(db, make_user):
+    user = make_user()
+    pl = _mirror_with_an_item(db, user, source="local")
+    with pytest.raises(YouTubeError) as err:
+        plsync.plan_merge(db, user, pl, live=([], {"title": "Mixes", "item_count": 1}))
+    assert err.value.reason == "emptyAnswer"

backend/tests/test_feed_views.py

@@ -12,6 +12,8 @@ from datetime import datetime, timezone
 
 import pytest
 
+from app import feedquery
+
 from app.models import Channel, ChannelTag, Subscription, Tag, Video, VideoState
 
 
@@ -168,9 +170,50 @@ _SUMMARY_CASES = [
     "show=all&untagged=true&tags={L1}",
     "show=all&q=clip",
     "show=unwatched",
+    # A deleted tag's id (a saved view or the feed state still holds it) matches nothing.
+    "show=all&tags=987654",
+    "show=all&tags={L1}&tags=987654",
 ]
 
 
+def test_a_deleted_tags_id_filters_to_nothing_not_to_everything(db, as_user, make_user):
+    """A saved view or the feed's filter state keeps a tag id after the tag is deleted. The feed used
+    to drop an unknown id, so that view silently showed the WHOLE feed under its old name (E32 S2).
+    A filter on a tag that no longer exists matches nothing; the chip says the tag is gone."""
+    user, tag_ids = _seed_tagged(db, make_user)
+    client = as_user(user)
+    everything = client.get("/api/feed/count?show=all")
+    assert everything.status_code == 200
+    assert everything.json()["count"] == 8
+    for qs in ("show=all&tags=987654", f"show=all&tags={tag_ids['L1']}&tags=987654"):
+        r = client.get(f"/api/feed/count?{qs}")
+        assert r.status_code == 200
+        assert r.json()["count"] == 0, qs
+        r = client.get(f"/api/feed?{qs}")
+        assert r.status_code == 200
+        assert r.json()["items"] == [], qs
+
+
+def test_another_users_private_tag_answers_like_one_that_does_not_exist(db, as_user, make_user):
+    """The category split resolved any tag id, so a foreign PRIVATE tag landed in its real category
+    and the summary's facets differed from a non-existent id's: an oracle for which foreign ids exist
+    (E32 review). Both must now read as "missing"."""
+    user, tag_ids = _seed_tagged(db, make_user)
+    stranger = make_user(email="stranger@example.com")
+    private = Tag(user_id=stranger.id, name="Secret", category="language")
+    db.add(private)
+    db.commit()
+    assert feedquery.tags_by_category(db, user, [tag_ids["L1"], private.id]) == {
+        "language": [tag_ids["L1"]],
+        feedquery.MISSING_TAG_CATEGORY: [private.id],
+    }
+    client = as_user(user)
+    foreign = client.get(f"/api/feed/summary?show=all&tags={tag_ids['T1']}&tags={private.id}")
+    absent = client.get(f"/api/feed/summary?show=all&tags={tag_ids['T1']}&tags=987654")
+    assert foreign.status_code == absent.status_code == 200
+    assert foreign.json() == absent.json()
+
+
 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

backend/tests/test_last_login.py

@@ -100,7 +100,12 @@ def test_the_admin_user_list_carries_last_login(as_user, db, make_user):
 def test_the_account_sees_its_own_last_sign_in(client, db, make_user):
     # Settings → Account shows it (prod UAT 2026-09-19: only the admin's user list did).
     make_user(email="me@example.com", password=_PW)
-    client.post("/auth/password-login", json={"email": "me@example.com", "password": _PW})
+    assert (
+        client.post(
+            "/auth/password-login", json={"email": "me@example.com", "password": _PW}
+        ).status_code
+        == 200
+    )
 
     stamp = client.get("/api/me").json()["last_login_at"]
 

backend/tests/test_logs.py

@@ -277,7 +277,7 @@ def test_a_signed_in_request_is_never_capped_and_names_its_account(sink):
 
     client = TestClient(app)
     for _ in range(logs.ANONYMOUS_LINES_PER_MINUTE + 3):
-        client.get("/api/me")
+        assert client.get("/api/me").status_code == 200
     records = sink.records[-(logs.ANONYMOUS_LINES_PER_MINUTE + 3) :]
     assert all(getattr(r, logs.PERSIST, True) for r in records)
     assert sink.objects()[-1]["user_id"] == 42 and "user_id" not in sink.objects()[-1]["attrs"]
@@ -325,9 +325,9 @@ def test_the_log_consoles_own_reads_are_debug_but_its_failures_are_not(sink):
     http = logging.getLogger("siftlode.http")
     http.setLevel(logs.TRACE)
     client = _client()
-    client.get("/api/admin/logs/facets")
+    assert client.get("/api/admin/logs/facets").status_code == 200
     assert sink.objects()[-1]["level"] == "DEBUG"
-    client.get("/api/admin/logs/facets?fail=1")
+    assert client.get("/api/admin/logs/facets?fail=1").status_code == 400
     assert sink.objects()[-1]["level"] == "WARNING"
 
 
@@ -344,7 +344,7 @@ def test_a_polled_read_is_debug_a_write_to_the_same_route_is_not(sink):
     r = client.post("/api/messages/unread_count")
     assert sink.objects()[-1]["level"] == "INFO"
     assert "X-Log-Quiet" not in r.headers
-    client.get("/api/videos/abc")
+    assert client.get("/api/videos/abc").status_code == 200
     assert sink.objects()[-1]["level"] == "INFO"
 
 
@@ -360,7 +360,7 @@ def test_every_polled_route_is_a_route_the_app_has():
 
 def test_a_failing_request_is_logged_by_status_and_an_unhandled_error_is_logged_at_all(sink):
     client = _client()
-    client.get("/api/videos/missing/deeper")  # 404 from the router
+    assert client.get("/api/videos/missing/deeper").status_code == 404  # 404 from the router
     assert sink.objects()[-1]["level"] == "WARNING"
     client.get("/boom")
     payload = sink.objects()[-1]

backend/tests/test_logsink.py

@@ -259,7 +259,7 @@ def test_the_writer_drains_what_was_queued_when_it_is_stopped(db):
     log.addHandler(sink)
     try:
         for i in range(logsink.BATCH_MAX + 5):
-            # noqa G004: the f-string is the POINT — a distinct rendered message per line is
+            # G004: the f-string is the POINT — a distinct rendered message per line is
             # what keeps the flood limiter (which groups by template) out of this case.
             log.warning(f"line {i}")  # noqa: G004
     finally:

backend/tests/test_mail_language.py

@@ -154,8 +154,18 @@ def test_an_access_request_records_the_language_it_was_made_in(db, client):
 
 
 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"})
+    assert (
+        client.post(
+            "/auth/request-access", json={"email": "asking@example.com", "lang": "en"}
+        ).status_code
+        == 200
+    )
+    assert (
+        client.post(
+            "/auth/request-access", json={"email": "asking@example.com", "lang": "hu"}
+        ).status_code
+        == 200
+    )
 
     db.expire_all()
     inv = db.execute(select(Invite).where(Invite.email == "asking@example.com")).scalar_one()
@@ -165,7 +175,12 @@ def test_asking_again_from_another_language_updates_the_row(db, client):
 
 
 def test_an_unsupported_language_is_ignored_rather_than_stored(db, client):
-    client.post("/auth/request-access", json={"email": "asking@example.com", "lang": "../../etc"})
+    assert (
+        client.post(
+            "/auth/request-access", json={"email": "asking@example.com", "lang": "../../etc"}
+        ).status_code
+        == 200
+    )
 
     inv = db.execute(select(Invite).where(Invite.email == "asking@example.com")).scalar_one()
     assert inv.lang is None
@@ -194,7 +209,12 @@ def test_the_confirmation_mail_is_written_in_the_accounts_language(db, client, m
     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"})
+    assert (
+        client.post(
+            "/auth/register", json={"email": "hu@example.com", "password": _PW, "lang": "hu"}
+        ).status_code
+        == 200
+    )
 
     (_, subject, body) = sent[0]
     assert subject == mailtext.MAIL_TEXT["verify_email.subject"]["hu"]
@@ -209,7 +229,12 @@ def test_the_approval_mail_answers_in_the_language_the_request_was_made_in(
     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"})
+    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()
     sent.clear()  # drop the admin notification; this test is about the reply to the requester
 
@@ -227,11 +252,16 @@ def test_a_denial_answers_in_that_language_too(db, client, make_user, as_user, m
     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"})
+    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()
     sent.clear()
 
-    as_user(admin).post(f"/api/admin/invites/{inv.id}/deny")
+    assert as_user(admin).post(f"/api/admin/invites/{inv.id}/deny").status_code == 200
 
     assert sent[0][1] == mailtext.MAIL_TEXT["access_denied.subject"]["hu"]
 

backend/tests/test_maintenance_lifecycle.py

@@ -0,0 +1,182 @@
+"""sync/maintenance — the job that HARD-DELETES videos (E32 S2: 19% covered).
+
+Its lifecycle: a video missing from videos.list is flagged and hidden; after the grace period a
+still-missing one is deleted (cascading to every playlist that held it) and each affected user
+gets one notification; a video that answers again is unhidden. A live broadcast is never a delete
+trigger, and an upcoming premiere that never went live is. YouTube is a fake that answers
+videos.list from a dict.
+"""
+
+from datetime import timedelta
+
+import pytest
+from sqlalchemy import select
+
+from app.models import Channel, Notification, Playlist, PlaylistItem, Video
+from app.sync import maintenance
+from app.utils import now_utc
+
+
+class _YT:
+    def __init__(self, items: dict[str, dict]):
+        self.items = items
+        self.asked: list[list[str]] = []
+
+    def get_videos(self, ids):
+        self.asked.append(list(ids))
+        return [self.items[i] for i in ids if i in self.items]
+
+
+def _item(vid: str, **snippet) -> dict:
+    return {"id": vid, "snippet": {"title": vid, **snippet}}
+
+
+@pytest.fixture
+def channel(db):
+    ch = Channel(id="UC_maint", title="Maint")
+    db.add(ch)
+    db.flush()
+    return ch
+
+
+def test_a_flagged_video_that_answers_again_is_unhidden(db, channel):
+    v = Video(
+        id="v1", channel_id=channel.id, unavailable_since=now_utc(), unavailable_reason="removed"
+    )
+    db.add(v)
+    db.commit()
+    out = maintenance._recheck_flagged(db, _YT({"v1": _item("v1")}), now_utc())
+    db.refresh(v)
+    assert v.unavailable_since is None and v.unavailable_reason is None
+    assert out == {"checked": 1, "recovered": 1, "deleted": 0, "notified": 0}
+
+
+def test_a_video_still_missing_inside_its_grace_period_is_kept_hidden(db, channel):
+    v = Video(
+        id="v1",
+        channel_id=channel.id,
+        unavailable_since=now_utc() - timedelta(days=maintenance.DEFAULT_GRACE_DAYS - 1),
+        unavailable_reason="removed",
+    )
+    db.add(v)
+    db.commit()
+    out = maintenance._recheck_flagged(db, _YT({}), now_utc())
+    assert db.get(Video, "v1") is not None
+    assert out["deleted"] == 0
+
+
+def test_past_the_grace_period_it_is_deleted_and_each_user_who_kept_it_told_once(
+    db, channel, make_user
+):
+    a, b = make_user(), make_user()
+    gone_since = now_utc() - timedelta(days=maintenance.DEFAULT_GRACE_DAYS + 1)
+    for vid in ("v1", "v2"):
+        db.add(
+            Video(
+                id=vid,
+                channel_id=channel.id,
+                title=f"T {vid}",
+                unavailable_since=gone_since,
+                unavailable_reason="removed",
+            )
+        )
+    pa = Playlist(user_id=a.id, name="A")
+    pb = Playlist(user_id=b.id, name="B")
+    db.add_all([pa, pb])
+    db.flush()
+    db.add_all(
+        [
+            PlaylistItem(playlist_id=pa.id, video_id="v1", position=0),
+            PlaylistItem(playlist_id=pa.id, video_id="v2", position=1),
+            PlaylistItem(playlist_id=pb.id, video_id="v2", position=0),
+        ]
+    )
+    db.commit()
+    out = maintenance._recheck_flagged(db, _YT({}), now_utc())
+    db.expire_all()
+    assert db.get(Video, "v1") is None and db.get(Video, "v2") is None
+    assert db.execute(select(PlaylistItem)).scalars().all() == []  # the cascade
+    notes = {
+        n.user_id: n.data["count"]
+        for n in db.execute(select(Notification).where(Notification.type == "maintenance"))
+        .scalars()
+        .all()
+    }
+    assert notes == {a.id: 2, b.id: 1}  # one per user, not one per video
+    assert out == {"checked": 2, "recovered": 0, "deleted": 2, "notified": 2}
+
+
+def test_rolling_revalidation_flags_the_missing_and_keeps_a_live_stream(db, channel, monkeypatch):
+    monkeypatch.setattr(maintenance.sysconfig, "get_int", lambda db, key: 10)
+    monkeypatch.setattr(maintenance.quota, "backfill_reserve_reached", lambda: False)
+    db.add_all(
+        [
+            Video(id="ok", channel_id=channel.id),
+            Video(id="gone", channel_id=channel.id),
+            Video(id="live", channel_id=channel.id),
+        ]
+    )
+    db.commit()
+    yt = _YT({"ok": _item("ok"), "live": _item("live", liveBroadcastContent="live")})
+    out = maintenance._revalidate_rolling(db, yt, now_utc())
+    db.expire_all()
+    assert db.get(Video, "gone").unavailable_reason == "removed"
+    assert db.get(Video, "ok").unavailable_since is None
+    assert db.get(Video, "live").unavailable_since is None
+    assert out == {"checked": 3, "flagged": 1}
+    assert all(db.get(Video, v).last_checked_at is not None for v in ("ok", "gone", "live"))
+
+
+def test_a_run_asks_youtube_about_each_video_once(db, channel, monkeypatch, make_user):
+    # Phase 1 recovers v1; phase 2 must not take it as "not checked this run" and fetch it again.
+    monkeypatch.setattr(maintenance.sysconfig, "get_int", lambda db, key: 10)
+    monkeypatch.setattr(maintenance.quota, "backfill_reserve_reached", lambda: False)
+    yt = _YT({"v1": _item("v1"), "v2": _item("v2")})
+
+    class _Client:
+        def __init__(self, *_):
+            pass
+
+        def __enter__(self):
+            return yt
+
+        def __exit__(self, *_):
+            return False
+
+    monkeypatch.setattr(maintenance, "YouTubeClient", _Client)
+    monkeypatch.setattr(maintenance, "get_service_user", lambda db: make_user())
+    db.add_all(
+        [
+            Video(
+                id="v1",
+                channel_id=channel.id,
+                unavailable_since=now_utc(),
+                unavailable_reason="removed",
+            ),
+            Video(id="v2", channel_id=channel.id),
+        ]
+    )
+    db.commit()
+    maintenance.run_maintenance(db)
+    asked = [vid for batch in yt.asked for vid in batch]
+    assert sorted(asked) == ["v1", "v2"]
+
+
+def test_an_upcoming_premiere_counts_as_abandoned_only_when_it_never_went_live():
+    past = (now_utc() - timedelta(days=3)).isoformat()
+    soon = (now_utc() - timedelta(days=1)).isoformat()
+
+    def item(**live):
+        return {"snippet": {"liveBroadcastContent": "upcoming"}, "liveStreamingDetails": live}
+
+    assert maintenance._is_abandoned_upcoming(item(scheduledStartTime=past)) is True
+    assert maintenance._is_abandoned_upcoming(item(scheduledStartTime=soon)) is False
+    assert (
+        maintenance._is_abandoned_upcoming(item(scheduledStartTime=past, actualStartTime=past))
+        is False
+    )
+    assert (
+        maintenance._is_abandoned_upcoming({"snippet": {"liveBroadcastContent": "none"}}) is False
+    )
+    # …and an abandoned premiere has no grace period: the confirming sweep deletes it.
+    assert maintenance._grace_days("abandoned") == 0

backend/tests/test_playlist_add_position.py

@@ -97,7 +97,7 @@ def test_putting_a_removed_video_back_leaves_a_linked_list_clean(db, make_user,
     pl.synced_fingerprint = current_fingerprint(db, pl)
     pl.dirty = False
     db.commit()
-    client.delete(f"/api/playlists/{pl.id}/items/b")
+    assert client.delete(f"/api/playlists/{pl.id}/items/b").status_code == 200
     db.expire_all()
     assert db.get(Playlist, pl.id).dirty is True
     _add(client, pl.id, {"video_id": "b", "position": 1})

backend/tests/test_playlist_merge.py

@@ -12,8 +12,8 @@ import pytest
 
 from app.models import Channel, Playlist, PlaylistItem, Video
 from app.sync import playlists as pl_mod
+from app.sync.playlist_merge import merge_plan
 from app.sync.playlists import (
-    merge_plan,
     merge_playlist,
     parse_baseline,
     parse_unavailable,

backend/tests/test_plex_admin_routes.py

@@ -0,0 +1,154 @@
+"""routes/plex/admin — the connection test and the owner's watch-sync link (E32 S2: 37% covered).
+
+The connection test is the admin's one early warning that the media mount or path map is wrong, and
+it must not quote the server's URL back in a toast. The watch link runs the one-time "Plex is master"
+import exactly once. Plex itself is a stub.
+"""
+
+from sqlalchemy import select
+
+import app.routes.plex.admin as admin_routes
+from app import sysconfig
+from app.models import PlexLink
+from app.plex.client import PlexError, PlexNotConfigured
+
+
+class _Plex:
+    def __init__(self, *, sections=None, leaf=None, fail=None):
+        self._sections = sections or []
+        self._leaf = leaf
+        self._fail = fail
+        self.section_items_calls: list[str] = []
+
+    def __enter__(self):
+        if self._fail:
+            raise self._fail
+        return self
+
+    def __exit__(self, *exc):
+        return False
+
+    def server_info(self):
+        return {"friendlyName": "Basement", "version": "1.40"}
+
+    def sections(self):
+        return self._sections
+
+    def section_items(self, key, *_args):
+        self.section_items_calls.append(key)
+        return ([self._leaf] if self._leaf else []), 1
+
+
+SECTIONS = [
+    {"key": 1, "title": "Movies", "type": "movie", "count": 10},
+    {"key": 2, "title": "Shows", "type": "show", "count": 3},
+    {"key": 3, "title": "Music", "type": "artist", "count": 99},
+]
+LEAF = {"Media": [{"Part": [{"file": "/data/movies/a.mkv"}]}]}
+
+
+def _use(monkeypatch, plex):
+    monkeypatch.setattr(admin_routes, "PlexClient", lambda db: plex)
+
+
+def test_the_connection_test_lists_movie_and_show_sections_and_probes_one_file(
+    db, as_user, make_user, monkeypatch, tmp_path
+):
+    (tmp_path / "a.mkv").write_bytes(b"x")
+    sysconfig.set_value(db, "plex_path_map", f"/data/movies={tmp_path}")
+    sysconfig.set_value(db, "plex_libraries", "4")
+    db.commit()
+    # Only section 4 is enabled; the movie section listed first (1) must not be the one sampled.
+    other = {"key": 4, "title": "Kids", "type": "movie", "count": 2}
+    plex = _Plex(sections=[*SECTIONS, other], leaf=LEAF)
+    _use(monkeypatch, plex)
+    r = as_user(make_user(role="admin")).post("/api/plex/test")
+    assert r.status_code == 200, r.text
+    body = r.json()
+    assert body["server_name"] == "Basement"
+    assert [s["key"] for s in body["sections"]] == ["1", "2", "4"]  # music is not ours
+    assert body["media_check"] == {
+        "checked": True,
+        "ok": True,
+        "plex_path": "/data/movies/a.mkv",
+        "local_path": str(tmp_path / "a.mkv"),
+    }
+    assert plex.section_items_calls == ["4"]  # only an enabled movie section is sampled
+
+
+def test_a_wrong_mount_is_reported_and_an_empty_library_is_not_checked(
+    db, as_user, make_user, monkeypatch, tmp_path
+):
+    sysconfig.set_value(db, "plex_path_map", f"/data/movies={tmp_path}")
+    db.commit()
+    client = as_user(make_user(role="admin"))
+    _use(monkeypatch, _Plex(sections=SECTIONS, leaf=LEAF))  # the file is not on the mount
+    check = client.post("/api/plex/test").json()["media_check"]
+    assert check["checked"] is True and check["ok"] is False
+
+    _use(monkeypatch, _Plex(sections=SECTIONS))
+    assert client.post("/api/plex/test").json()["media_check"] == {"checked": False}
+
+
+def test_a_failed_connection_says_so_without_quoting_the_server(
+    db, as_user, make_user, monkeypatch
+):
+    client = as_user(make_user(role="admin"))
+    _use(monkeypatch, _Plex(fail=PlexNotConfigured()))
+    r = client.post("/api/plex/test")
+    assert r.status_code == 400
+    assert r.json()["detail"]["reason"] == "plex_not_configured"
+
+    _use(monkeypatch, _Plex(fail=PlexError("GET http://10.0.0.5:32400/secret refused")))
+    r = client.post("/api/plex/test")
+    assert r.status_code == 422
+    assert r.json()["detail"]["reason"] == "plex_unreachable"
+    assert "10.0.0.5" not in r.text
+
+
+def test_plex_admin_routes_refuse_a_regular_user(db, as_user, make_user, monkeypatch):
+    _use(monkeypatch, _Plex(sections=SECTIONS))
+    client = as_user(make_user())
+    for path in ("/api/plex/test", "/api/plex/sync", "/api/plex/watch/import"):
+        assert client.post(path).status_code == 403, path
+    assert client.post("/api/plex/watch/link", json={"enabled": True}).status_code == 403
+
+
+def test_the_watch_link_imports_once_and_needs_plex_on(db, as_user, make_user, monkeypatch):
+    imports: list[int] = []
+
+    def fake_import(db_, link):
+        imports.append(link.user_id)
+        link.initial_import_done = True
+        db_.commit()
+        return {"imported": 7}
+
+    monkeypatch.setattr(admin_routes.plex_watch, "import_owner_watch_state", fake_import)
+    owner = make_user(role="admin")
+    client = as_user(owner)
+
+    r = client.post("/api/plex/watch/link", json={"enabled": True})
+    assert r.status_code == 409 and r.json()["detail"]["reason"] == "plex_disabled"
+    assert client.post("/api/plex/watch/import").json()["detail"]["reason"] == "watch_sync_off"
+
+    sysconfig.set_value(db, "plex_enabled", True)
+    db.commit()
+    first = client.post("/api/plex/watch/link", json={"enabled": True})
+    assert first.status_code == 200
+    assert first.json()["import"] == {"imported": 7}
+    assert first.json()["linked"] and first.json()["sync_enabled"] and first.json()["uses_admin"]
+
+    assert client.post("/api/plex/watch/link", json={"enabled": False}).json()["import"] is None
+    again = client.post("/api/plex/watch/link", json={"enabled": True})
+    assert again.json()["import"] is None  # the one-time import does not run twice
+    assert imports == [owner.id]
+
+    status = client.get("/api/plex/watch/link")
+    assert status.status_code == 200
+    assert status.json()["initial_import_done"] is True
+    links = db.execute(select(PlexLink).where(PlexLink.user_id == owner.id)).scalars().all()
+    assert len(links) == 1  # toggling never creates a second link
+
+    rerun = client.post("/api/plex/watch/import")
+    assert rerun.status_code == 200 and rerun.json()["import"] == {"imported": 7}
+    assert imports == [owner.id, owner.id]

backend/tests/test_plex_client.py

@@ -0,0 +1,204 @@
+"""plex/client — the one door to the Plex server (E32 S2: 31% covered).
+
+What matters here is what the callers cannot see: a failure must surface as PlexError (never as an
+empty answer), the paged reads must stop where they should, and the write URIs must be well formed.
+The network is an httpx MockTransport; the configuration is stubbed.
+"""
+
+import httpx
+import pytest
+
+from app.plex import client as plex_client
+from app.plex.client import PlexClient, PlexError, PlexNotConfigured
+
+
+@pytest.fixture
+def plex(monkeypatch):
+    """A PlexClient on a stub server; set `routes[path] = handler-or-json` per test."""
+    routes: dict = {}
+    seen: list[httpx.Request] = []
+
+    def transport(request: httpx.Request) -> httpx.Response:
+        seen.append(request)
+        answer = routes.get(request.url.path)
+        if answer is None:
+            return httpx.Response(404)
+        if callable(answer):
+            return answer(request)
+        return httpx.Response(200, json={"MediaContainer": answer})
+
+    real = httpx.Client
+    monkeypatch.setattr(
+        plex_client.httpx,
+        "Client",
+        lambda **kw: real(transport=httpx.MockTransport(transport), **kw),
+    )
+    conf = {"plex_server_url": "http://plex.test:32400/", "plex_server_token": "tok"}
+    monkeypatch.setattr(plex_client.sysconfig, "get_str", lambda db, key: conf[key])
+    c = PlexClient(None)  # type: ignore[arg-type]  # the stubbed config never reads the session
+    c.routes, c.seen = routes, seen  # type: ignore[attr-defined]
+    yield c
+    c.close()
+
+
+def test_an_unconfigured_server_is_refused_up_front(monkeypatch):
+    monkeypatch.setattr(plex_client.sysconfig, "get_str", lambda db, key: "")
+    with pytest.raises(PlexNotConfigured):
+        PlexClient(None)  # type: ignore[arg-type]
+
+
+def test_reads_carry_the_token_and_unwrap_the_container(plex):
+    plex.routes["/library/sections"] = {"Directory": [{"key": "1", "type": "movie"}]}
+    assert plex.sections() == [{"key": "1", "type": "movie"}]
+    req = plex.seen[-1]
+    assert str(req.url) == "http://plex.test:32400/library/sections"
+    assert req.headers["x-plex-token"] == "tok"
+    assert req.headers["accept"] == "application/json"
+
+
+@pytest.mark.parametrize(
+    "answer",
+    [
+        lambda r: httpx.Response(500),
+        lambda r: httpx.Response(200, text="<html>login</html>"),
+        lambda r: (_ for _ in ()).throw(httpx.ConnectError("down", request=r)),
+    ],
+    ids=["http-500", "not-json", "unreachable"],
+)
+def test_a_failed_read_is_a_plex_error_never_an_empty_answer(plex, answer):
+    plex.routes["/library/sections"] = answer
+    with pytest.raises(PlexError):
+        plex.sections()
+
+
+def test_a_section_page_asks_for_guids_and_reports_the_server_total(plex):
+    plex.routes["/library/sections/7/all"] = {"Metadata": [{"ratingKey": "1"}], "totalSize": 250}
+    items, total = plex.section_items("7", 1, 200, 50)
+    assert items == [{"ratingKey": "1"}] and total == 250
+    params = plex.seen[-1].url.params
+    assert params["includeGuids"] == "1" and params["type"] == "1"
+    assert params["X-Plex-Container-Start"] == "200" and params["X-Plex-Container-Size"] == "50"
+
+    # Measured on the real server (E32 review): a paged request carries `totalSize` even when the
+    # page is empty, past the end, or the section holds nothing — `size: 0, totalSize: 0`.
+    plex.routes["/library/sections/7/all"] = {"Metadata": [], "size": 0, "totalSize": 0}
+    assert plex.section_items("7", 2) == ([], 0)
+    # No total at all is not "0": the caller must not read it as a complete, empty section.
+    plex.routes["/library/sections/7/all"] = {"Metadata": []}
+    assert plex.section_items("7", 2) == ([], None)
+    # …and `size` is THIS page's count, never the section's: one full page is not the whole section.
+    plex.routes["/library/sections/7/all"] = {"Metadata": [{"ratingKey": "1"}], "size": 1}
+    assert plex.section_items("7", 2) == ([{"ratingKey": "1"}], None)
+
+
+def test_related_flattens_the_hubs_and_degrades_to_empty(plex):
+    plex.routes["/library/metadata/5/related"] = {
+        "Hub": [{"Metadata": [{"ratingKey": "a"}]}, {"Metadata": [{"ratingKey": "b"}]}, {}]
+    }
+    assert [m["ratingKey"] for m in plex.related("5")] == ["a", "b"]
+    plex.routes["/library/metadata/5/related"] = lambda r: httpx.Response(500)
+    assert plex.related("5") == []
+
+
+def test_metadata_is_the_first_item_or_none(plex):
+    plex.routes["/library/metadata/9"] = {"Metadata": [{"ratingKey": "9", "title": "X"}]}
+    assert plex.metadata("9", markers=True) == {"ratingKey": "9", "title": "X"}
+    assert plex.seen[-1].url.params["includeMarkers"] == "1"
+    plex.routes["/library/metadata/9"] = {}
+    assert plex.metadata("9") is None
+
+
+def _history(rows_by_start: dict[int, list[dict]]):
+    def answer(request: httpx.Request) -> httpx.Response:
+        start = int(request.url.params["X-Plex-Container-Start"])
+        return httpx.Response(
+            200, json={"MediaContainer": {"Metadata": rows_by_start.get(start, [])}}
+        )
+
+    return answer
+
+
+def test_watch_history_pages_until_the_cutoff_and_keeps_only_the_owner(plex):
+    plex.routes["/status/sessions/history/all"] = _history(
+        {
+            0: [
+                {"ratingKey": "1", "viewedAt": 500, "accountID": 2},
+                {"ratingKey": "2", "viewedAt": 400, "accountID": 1},
+            ],
+            2: [
+                {"ratingKey": "3", "viewedAt": 300, "accountID": 1},
+                {"ratingKey": "4", "viewedAt": 100, "accountID": 1},
+            ],
+            4: [{"ratingKey": "never", "viewedAt": 50, "accountID": 1}],
+        }
+    )
+    rows = plex.watch_history(min_viewed_at=200, account_id=1, size=2)
+    assert [r["ratingKey"] for r in rows] == ["2", "3"]  # page 2 reached, the cutoff stops it
+    assert [int(r.url.params["X-Plex-Container-Start"]) for r in plex.seen] == [0, 2]
+
+
+def test_watch_history_stops_on_a_short_page_and_at_the_page_cap(plex):
+    plex.routes["/status/sessions/history/all"] = _history({0: [{"ratingKey": "1", "viewedAt": 9}]})
+    assert [r["ratingKey"] for r in plex.watch_history(size=2)] == ["1"]
+    assert len(plex.seen) == 1
+
+    full = [{"ratingKey": "r", "viewedAt": 9}, {"ratingKey": "r", "viewedAt": 9}]
+    plex.routes["/status/sessions/history/all"] = lambda r: httpx.Response(
+        200, json={"MediaContainer": {"Metadata": full}}
+    )
+    plex.seen.clear()
+    assert len(plex.watch_history(size=2, max_pages=3)) == 6
+    assert len(plex.seen) == 3
+
+
+def test_a_collection_is_created_with_a_well_formed_uri(plex):
+    plex.routes["/identity"] = {"machineIdentifier": "abc"}
+    plex.routes["/library/collections"] = {"Metadata": [{"ratingKey": "c1"}]}
+    assert plex.create_collection("3", "Best of: 90s", "42") == {"ratingKey": "c1"}
+    params = plex.seen[-1].url.params
+    assert plex.seen[-1].method == "POST"
+    assert params["title"] == "Best of: 90s" and params["sectionId"] == "3"
+    assert params["uri"] == "server://abc/com.plexapp.plugins.library/library/metadata/42"
+
+    plex.routes["/library/collections"] = {}
+    with pytest.raises(PlexError):
+        plex.create_collection("3", "Empty", "42")
+    assert [r.url.path for r in plex.seen].count("/identity") == 1  # cached
+
+
+def test_a_server_without_a_machine_id_refuses_the_write(plex):
+    """No machineIdentifier used to become `server:///…` in the write URI — a malformed request
+    Plex answers in its own way. It is refused here, named (E32 S2)."""
+    plex.routes["/identity"] = {}
+    plex.routes["/library/collections"] = {"Metadata": [{"ratingKey": "c1"}]}
+    with pytest.raises(PlexError, match="machine"):
+        plex.create_collection("3", "T", "42")
+    assert all(r.url.path == "/identity" for r in plex.seen)
+
+
+def test_watch_state_writes_target_the_library_item(plex):
+    for path in ("/:/scrobble", "/:/unscrobble", "/:/timeline"):
+        plex.routes[path] = lambda r: httpx.Response(200)  # Plex answers with an empty body
+    plex.scrobble("42")
+    assert plex.seen[-1].url.params["key"] == "42"
+    plex.unscrobble("42")
+    assert plex.seen[-1].url.path == "/:/unscrobble"
+    plex.set_timeline("42", 61_500.7, 120_000)  # type: ignore[arg-type]
+    p = plex.seen[-1].url.params
+    assert p["key"] == "/library/metadata/42" and p["time"] == "61500" and p["state"] == "stopped"
+    plex.routes["/:/scrobble"] = lambda r: httpx.Response(401)
+    with pytest.raises(PlexError):
+        plex.scrobble("42")
+
+
+def test_an_image_is_resized_by_plex_when_a_box_is_given(plex):
+    plex.routes["/photo/:/transcode"] = lambda r: httpx.Response(
+        200, content=b"small", headers={"Content-Type": "image/webp"}
+    )
+    plex.routes["/library/metadata/1/thumb/2"] = lambda r: httpx.Response(200, content=b"full")
+    assert plex.image_bytes("/library/metadata/1/thumb/2", 300, 450) == (b"small", "image/webp")
+    assert plex.seen[-1].url.params["url"] == "/library/metadata/1/thumb/2"
+    body, ctype = plex.image_bytes("/library/metadata/1/thumb/2")
+    assert body == b"full" and ctype == "image/jpeg"
+    with pytest.raises(PlexError):
+        plex.raw_get("/library/streams/404")

backend/tests/test_plex_image_sizes.py

@@ -67,7 +67,7 @@ def test_each_variant_is_cut_at_its_own_size(db, make_user, monkeypatch, tmp_pat
     ]
     # Each cut is cached under its own name: asking again reaches Plex no more.
     for variant in ("thumb", "thumb_sm", "art", "art_sm"):
-        client.get(f"/api/plex/image/pm1?variant={variant}")
+        assert client.get(f"/api/plex/image/pm1?variant={variant}").status_code == 200
     assert len(_FakePlex.calls) == 4
 
 

backend/tests/test_plex_overlay.py

@@ -16,18 +16,21 @@ from app import sysconfig
 from app.db import engine
 from app.models import PlexItem, PlexLibrary, PlexShow
 from app.plex.genres import hu_genre, hu_genres
-from app.plex.sync import _apply_item, _canonical_guid, _sync_overlay
+from app.plex.overlay import sync_overlay
+from app.plex.sync import _apply_item, _canonical_guid
 from app.plex.query import content_libs
 
 
 class _StubPlex:
-    """Minimal PlexClient stand-in: _sync_overlay only calls section_items via _paginate."""
+    """Minimal PlexClient stand-in: sync_overlay only calls section_items via _paginate. `total`
+    over the item count is a listing cut short (the server said more than it handed over)."""
 
-    def __init__(self, items: list[dict]):
+    def __init__(self, items: list[dict], total: int | None = None):
         self._items = items
+        self._total = len(items) if total is None else total
 
     def section_items(self, key, item_type, start, size):
-        return self._items[start : start + size], len(self._items)
+        return self._items[start : start + size], self._total
 
 
 def _hu_movie(rk: str, title: str, summary: str, genres: list[str], guid: str | None) -> dict:
@@ -71,7 +74,7 @@ def test_sync_overlay_writes_hu_onto_matched_en_rows(db):
         ]
     )
     stats = {"overlaid": 0}
-    _sync_overlay(db, stub, hu_lib, en_lib.id, stats)
+    sync_overlay(db, stub, hu_lib, en_lib.id, stats)
     db.commit()
 
     db.refresh(matched)
@@ -185,13 +188,51 @@ def test_overlay_reconcile_clears_stale_hu_when_twin_vanishes(db):
     )
     db.add(row)
     db.commit()
-    # The HU section no longer lists this film (empty overlay).
-    _sync_overlay(db, _StubPlex([]), hu_lib, en_lib.id, {"overlaid": 0})
+    # The HU section, read in full, no longer lists this film (only another one).
+    other = _hu_movie("h9", "Más", "más", [], "tmdb://99")
+    sync_overlay(db, _StubPlex([other]), hu_lib, en_lib.id, {"overlaid": 0})
     db.commit()
     db.refresh(row)
     assert row.title_hu is None and row.summary_hu is None and row.genres_hu is None
 
 
+def test_a_listing_cut_short_keeps_the_hungarian_text_it_did_not_reach(db):
+    """E32 S2: the reconcile clears HU text only after a COMPLETE listing. A walk a Plex hiccup cut
+    short (an empty page before the server's total), or an empty section, says nothing about the
+    titles it did not reach — clearing them dropped their Hungarian text until the next full sync."""
+    en_lib = PlexLibrary(plex_key="4", title="Movies", kind="movie")
+    hu_lib = PlexLibrary(plex_key="9", title="Filmek", kind="movie", metadata_lang="hu")
+    db.add_all([en_lib, hu_lib])
+    db.flush()
+    hu_lib.overlay_of = en_lib.id
+    kept = PlexItem(
+        rating_key="m1",
+        library_id=en_lib.id,
+        kind="movie",
+        title="Heat",
+        guid="tmdb:1",
+        title_hu="Szemtől szemben",
+        summary_hu="régi",
+        genres_hu=["Akció"],
+    )
+    fresh = PlexItem(rating_key="m2", library_id=en_lib.id, kind="movie", title="Up", guid="tmdb:2")
+    db.add_all([kept, fresh])
+    db.commit()
+    stats: dict = {}
+    reached = _hu_movie("h2", "Fel", "fel", [], "tmdb://2")
+    sync_overlay(db, _StubPlex([reached], total=2), hu_lib, en_lib.id, stats)
+    db.commit()
+    db.refresh(kept)
+    db.refresh(fresh)
+    assert kept.title_hu == "Szemtől szemben" and kept.summary_hu == "régi"
+    assert fresh.title_hu == "Fel"  # what the listing did reach is still applied
+    assert stats["overlay_incomplete"] == 1
+    sync_overlay(db, _StubPlex([]), hu_lib, en_lib.id, {})  # an empty section: the same answer
+    db.commit()
+    db.refresh(kept)
+    assert kept.title_hu == "Szemtől szemben"
+
+
 def test_apply_item_keeps_prior_guid_when_listing_lacks_guid():
     row = PlexItem(rating_key="m1", kind="movie", guid="tmdb:1")
     _apply_item(row, lib_id=7, kind="movie", meta={"title": "Heat"})  # no Guid array
@@ -225,7 +266,7 @@ def test_overlay_applies_to_all_editions_sharing_a_guid(db):
         ]
     )
     stats = {"overlaid": 0}
-    _sync_overlay(db, stub, hu_lib, en_lib.id, stats)
+    sync_overlay(db, stub, hu_lib, en_lib.id, stats)
     db.commit()
     db.refresh(ed1)
     db.refresh(ed2)
@@ -291,7 +332,7 @@ def test_a_show_overlay_writes_hungarian_episode_titles_and_summaries(db):
             ],
         }
     )
-    _sync_overlay(db, stub, hu_lib, en_lib.id, {})
+    sync_overlay(db, stub, hu_lib, en_lib.id, {})
     db.commit()
     db.refresh(ep)
     db.refresh(show)
@@ -328,7 +369,7 @@ def test_the_overlay_gives_every_row_one_hungarian_word_per_genre(db):
         "h1", "Szemtől szemben", "HU.", ["Action", "Bűnügyi", "Drama", "Dráma"], "tmdb://1"
     )
     meta["tagline"] = "Magyar mottó."
-    _sync_overlay(db, _StubPlex([meta]), hu_lib, en_lib.id, {})
+    sync_overlay(db, _StubPlex([meta]), hu_lib, en_lib.id, {})
     db.commit()
     db.refresh(twin)
     db.refresh(lone)
@@ -353,7 +394,7 @@ def test_a_twin_without_genres_keeps_the_rows_own_hungarian_list(db):
     )
     db.add(row)
     db.commit()
-    _sync_overlay(
+    sync_overlay(
         db,
         _StubPlex([_hu_movie("h1", "Szemtől szemben", "HU.", [], "tmdb://1")]),
         hu_lib,

backend/tests/test_plex_paths.py

@@ -0,0 +1,82 @@
+"""plex/paths — the Plex-side path → local mount translation (E32 S2: 23% covered, and a wrong answer
+here reads as "media file not found" for a whole library at once, with nothing else failing).
+
+Pure logic: the admin map is read through sysconfig, stubbed per test.
+"""
+
+from pathlib import Path
+
+import pytest
+
+from app.plex import paths
+
+
+@pytest.fixture
+def path_map(monkeypatch):
+    def use(raw: str) -> None:
+        monkeypatch.setattr(paths.sysconfig, "get_str", lambda db, key: raw)
+
+    return use
+
+
+def test_the_map_parses_both_separators_drops_junk_and_puts_the_longest_prefix_first():
+    raw = " /data=/mnt/a ,\n/data/movies = /mnt/m\nnot-a-pair,=/x,/y=, /data/tv=/mnt/tv "
+    assert paths.parse_map(raw) == [
+        ("/data/movies", "/mnt/m"),
+        ("/data/tv", "/mnt/tv"),
+        ("/data", "/mnt/a"),
+    ]
+    assert paths.parse_map("") == []
+
+
+def test_the_longest_matching_prefix_wins(path_map):
+    path_map("/data=/mnt/a,/data/movies=/mnt/m")
+    assert paths.map_path(None, "/data/movies/Foo.mkv") == str(Path("/mnt/m") / "Foo.mkv")
+    assert paths.map_path(None, "/data/tv/Bar.mkv") == str(Path("/mnt/a") / "tv/Bar.mkv")
+
+
+def test_a_prefix_matches_only_at_a_path_boundary(path_map):
+    # "/data/movies2" shares the characters of "/data/movies" but is another folder.
+    path_map("/data/movies=/mnt/m")
+    assert paths.map_path(None, "/data/movies2/Foo.mkv") == "/data/movies2/Foo.mkv"
+
+
+def test_the_prefix_itself_and_a_trailing_slash_in_the_map(path_map):
+    path_map("/data/movies/=/mnt/m")
+    assert paths.map_path(None, "/data/movies/Foo.mkv") == str(Path("/mnt/m") / "Foo.mkv")
+    path_map("/data/movies=/mnt/m")
+    assert paths.map_path(None, "/data/movies") == "/mnt/m"
+
+
+def test_no_map_leaves_the_path_as_plex_sees_it(path_map):
+    path_map("")
+    assert paths.map_path(None, "/data/movies/Foo.mkv") == "/data/movies/Foo.mkv"
+
+
+def test_the_local_file_must_exist(path_map, tmp_path):
+    (tmp_path / "movies").mkdir()
+    (tmp_path / "movies" / "Foo.mkv").write_bytes(b"x")
+    path_map(f"/data={tmp_path}")
+    assert (
+        paths.local_media_path(None, "/data/movies/Foo.mkv")
+        == (tmp_path / "movies" / "Foo.mkv").resolve()
+    )
+    assert paths.local_media_path(None, "/data/movies/Missing.mkv") is None
+    assert paths.local_media_path(None, "/data/movies") is None  # a folder is not a file
+    assert paths.local_media_path(None, None) is None
+    assert paths.local_media_path(None, "") is None
+
+
+def test_a_path_that_cannot_be_resolved_is_logged_and_answered_none(path_map, monkeypatch, caplog):
+    path_map("")
+
+    def broken(self, strict=False):
+        raise OSError("dead mount")
+
+    monkeypatch.setattr(paths.Path, "resolve", broken)
+    assert paths.local_media_path(None, "/data/movies/Foo.mkv") is None
+    rec = next(
+        r for r in caplog.records if getattr(r, "event", None) == "plex.paths.resolve_failed"
+    )
+    # The title stays out of the log line: the path carries it.
+    assert "Foo" not in rec.getMessage() and rec.attrs == {"reason": "OSError"}

backend/tests/test_plex_playlist_add_positions.py

@@ -105,8 +105,11 @@ def test_remove_then_put_back_is_no_change(db, make_user, as_user):
     user = make_user()
     pl = _seed(db, user, ["a", "b", "c", "d"], extra=())
     client = as_user(user)
-    client.post(
-        f"/api/plex/playlists/{pl.id}/items/remove-bulk", json={"item_rating_keys": ["b", "d"]}
+    assert (
+        client.post(
+            f"/api/plex/playlists/{pl.id}/items/remove-bulk", json={"item_rating_keys": ["b", "d"]}
+        ).status_code
+        == 200
     )
     assert _order(db, pl.id)[0] == ["a", "c"]
     _add(client, pl.id, ["b", "d"], [1, 3])

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
+import sys
 from pathlib import Path
 
 import pytest
@@ -830,6 +831,46 @@ class TestProbeVideoKind:
         assert stream._probe_video_kind(Path("/x")) == stream._VK_HWSAFE
 
 
+class TestProbeExitStatus:
+    """A probe whose ffprobe EXITS NON-ZERO is a failed probe, not an answer (E32). Each probe used to
+    read stdout without looking at the exit status, so a refusing ffprobe silently picked the fallback
+    — HW-safe, single audio, the requested offset — and skipped the warning its except branch promises.
+    Drives the REAL subprocess.run with the probe's own kwargs against a stand-in command that prints a
+    plausible answer and then fails, so the test fails whenever the exit status is ignored."""
+
+    @staticmethod
+    def _failing_ffprobe(monkeypatch, stdout: str):
+        real_run = stream.subprocess.run
+        script = f"import sys; sys.stdout.write({stdout!r}); sys.exit(1)"
+        monkeypatch.setattr(
+            stream.subprocess,
+            "run",
+            lambda _cmd, **kw: real_run([sys.executable, "-c", script], **kw),
+        )
+
+    @staticmethod
+    def _events(caplog) -> list[str]:
+        return [getattr(r, "event", "") for r in caplog.records]
+
+    def test_video_kind(self, monkeypatch, caplog):
+        self._failing_ffprobe(monkeypatch, "pix_fmt=yuv420p10le\ncolor_transfer=smpte2084\n")
+        with caplog.at_level("INFO"):
+            assert stream._probe_video_kind(Path("/x")) == stream._VK_HWSAFE
+        assert "plex.stream.probe_kind_failed" in self._events(caplog)
+
+    def test_audio_langs(self, monkeypatch, caplog):
+        self._failing_ffprobe(monkeypatch, "hun\neng\n")
+        with caplog.at_level("INFO"):
+            assert stream._probe_audio_langs(Path("/x")) == []
+        assert "plex.stream.probe_audio_failed" in self._events(caplog)
+
+    def test_first_pts(self, monkeypatch, caplog):
+        self._failing_ffprobe(monkeypatch, "12.5\n")
+        with caplog.at_level("INFO"):
+            assert stream._probe_first_pts(Path("/x")) is None
+        assert "plex.stream.first_pts_probe_failed" in self._events(caplog)
+
+
 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

backend/tests/test_plex_subtitle_prepare.py

@@ -208,7 +208,7 @@ def test_an_unshowable_track_says_why_and_maps_to_a_status(client, monkeypatch):
         raise subtitles.SubtitleUnavailable("bitmap")
 
     monkeypatch.setattr(subtitles, "_extract_and_publish", _bitmap)
-    client.get("/api/plex/subtitle/98614/0/status")
+    assert client.get("/api/plex/subtitle/98614/0/status").status_code == 200
     pool.run_all()
     st = client.get("/api/plex/subtitle/98614/0/status").json()
     assert st["state"] == "failed" and st["code"] == "bitmap"

backend/tests/test_plex_watch_reconcile.py

@@ -0,0 +1,277 @@
+"""The daily full watch reconcile (`run_plex_watch_reconcile`) — the one pass that DELETES watch state:
+a mirrored row Plex no longer has a record for is read as "Plex un-watched it" and cleared. E32 S2
+found it trusting a scan a Plex hiccup had cut short; these hold what it may and may not clear.
+"""
+
+import pytest
+from sqlalchemy import select
+
+from app import sysconfig
+from app.models import PlexItem, PlexLibrary, PlexLink, PlexState, User
+from app.plex import watch_sync
+
+
+class _FakePlex:
+    """A PlexClient stand-in: one movie section whose listing reports `total` (more than it hands
+    over = a walk cut short), plus any `more` sections as `(type, leaves, total)` — listed AFTER
+    the movies — and a record of every write the reconcile sends back to Plex."""
+
+    def __init__(self, leaves: list[dict], total: int | None = None, more=()):
+        self.listings = {"1": ("movie", leaves, len(leaves) if total is None else total)}
+        for i, (stype, extra, extra_total) in enumerate(more, start=2):
+            self.listings[str(i)] = (stype, extra, extra_total)
+        self.calls: list[tuple] = []
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *exc):
+        return False
+
+    def sections(self):
+        return [{"type": stype, "key": key} for key, (stype, _l, _t) in self.listings.items()]
+
+    def section_items(self, key, item_type, start, size):
+        _stype, leaves, total = self.listings[key]
+        return leaves[start : start + size], total
+
+    def scrobble(self, rk):
+        self.calls.append(("scrobble", rk))
+
+    def unscrobble(self, rk):
+        self.calls.append(("unscrobble", rk))
+
+    def set_timeline(self, rk, time_ms, duration_ms):
+        self.calls.append(("timeline", rk, time_ms))
+
+
+@pytest.fixture
+def world(db):
+    """Five mirrored movies and the owner's link; each test sets the local states it needs."""
+    sysconfig.set_value(db, "plex_enabled", True)
+    lib = PlexLibrary(plex_key="1", title="Movies", kind="movie", enabled=True)
+    user = User(email="reconcile@example.com")
+    db.add_all([lib, user])
+    db.flush()
+    items = {}
+    for rk in ("m1", "m2", "m3", "m4", "m5"):
+        items[rk] = PlexItem(
+            rating_key=rk, library_id=lib.id, kind="movie", title=rk, duration_s=6000
+        )
+        db.add(items[rk])
+    db.add(
+        PlexLink(
+            user_id=user.id,
+            uses_admin=True,
+            sync_enabled=True,
+            initial_import_done=True,
+            plex_account_id=1,
+        )
+    )
+    db.flush()
+
+    def state(rk, **kw):
+        db.add(PlexState(user_id=user.id, item_id=items[rk].id, **kw))
+
+    def rows():
+        db.expire_all()
+        by_id = {i.id: rk for rk, i in items.items()}
+        return {
+            by_id[s.item_id]: (s.status, s.position_seconds, s.synced_to_plex)
+            for s in db.execute(select(PlexState).where(PlexState.user_id == user.id)).scalars()
+            if s.item_id in by_id  # the five movies; a test's own extra items it reads itself
+        }
+
+    return state, rows
+
+
+def _run(db, monkeypatch, plex):
+    monkeypatch.setattr(watch_sync, "PlexClient", lambda _db: plex)
+    return watch_sync.run_plex_watch_reconcile(db)
+
+
+def _local_states(state):
+    state("m1", status="watched", synced_to_plex=True)  # mirrored; Plex has no record now
+    state("m2", status="watched", synced_to_plex=False)  # local change that never reached Plex
+    state("m3", status="hidden", synced_to_plex=True)  # Siftlode-only, never cleared
+    state("m5", status="new", position_seconds=300, synced_to_plex=True)  # Plex says otherwise
+
+
+def test_a_complete_scan_clears_what_plex_unwatched_and_keeps_the_rest(db, monkeypatch, world):
+    state, rows = world
+    _local_states(state)
+    db.commit()
+    plex = _FakePlex(
+        [
+            {"ratingKey": "m3"},  # listed, no watch signal
+            {"ratingKey": "m4", "viewCount": 1, "lastViewedAt": 1_700_000_000},
+            {"ratingKey": "m5", "viewOffset": 120_000, "lastViewedAt": 1_700_000_000},
+        ]
+    )
+    out = _run(db, monkeypatch, plex)
+    assert rows() == {
+        "m2": ("watched", 0, True),  # re-pushed, then settled
+        "m3": ("hidden", 0, True),
+        "m4": ("watched", 0, True),  # pulled in
+        "m5": ("new", 120, True),  # Plex's position wins
+    }
+    assert ("scrobble", "m2") in plex.calls
+    assert out["cleared"] == 1 and out["repushed"] == 1 and "incomplete" not in out
+
+
+def test_a_scan_cut_short_clears_nothing(db, monkeypatch, world):
+    state, rows = world
+    _local_states(state)
+    db.commit()
+    # The server said 5, the walk got 3: m1 may simply not have been reached.
+    plex = _FakePlex(
+        [
+            {"ratingKey": "m3"},
+            {"ratingKey": "m4", "viewCount": 1, "lastViewedAt": 1_700_000_000},
+            {"ratingKey": "m5", "viewOffset": 120_000, "lastViewedAt": 1_700_000_000},
+        ],
+        total=5,
+    )
+    out = _run(db, monkeypatch, plex)
+    after = rows()
+    assert after["m1"] == ("watched", 0, True)  # NOT un-watched on a partial picture
+    assert after["m4"] == ("watched", 0, True) and after["m5"] == ("new", 120, True)  # pulls stand
+    assert after["m2"] == ("watched", 0, True)  # the dirty row is still pushed up
+    assert out["cleared"] == 0 and out["incomplete"] == 1
+
+
+_LISTED = [
+    {"ratingKey": "m3"},
+    {"ratingKey": "m4", "viewCount": 1, "lastViewedAt": 1_700_000_000},
+    {"ratingKey": "m5", "viewOffset": 120_000, "lastViewedAt": 1_700_000_000},
+]
+
+
+def test_a_genuinely_empty_second_section_still_lets_the_reconcile_clear(db, monkeypatch, world):
+    # The server SAYS the shows section holds 0: that is a complete listing, not a hiccup — before
+    # the E32 review it read as "incomplete" forever and un-watches never synced again.
+    state, rows = world
+    _local_states(state)
+    db.commit()
+    out = _run(db, monkeypatch, _FakePlex(_LISTED, more=[("show", [], 0)]))
+    assert "m1" not in rows()
+    assert out["cleared"] == 1 and "incomplete" not in out
+
+
+def _watched_episode_in_a_shows_section(db) -> int:
+    """A second mirrored section (key "2") holding one episode the owner has watched, synced."""
+    shows = PlexLibrary(plex_key="2", title="Shows", kind="show", enabled=True)
+    db.add(shows)
+    db.flush()
+    ep = PlexItem(rating_key="e1", library_id=shows.id, kind="episode", title="e1")
+    db.add(ep)
+    db.flush()
+    user_id = db.execute(select(PlexLink.user_id)).scalar_one()
+    db.add(PlexState(user_id=user_id, item_id=ep.id, status="watched", synced_to_plex=True))
+    return ep.id
+
+
+def _state_of(db, item_id: int) -> str | None:
+    db.expire_all()
+    st = db.execute(select(PlexState).where(PlexState.item_id == item_id)).scalar_one_or_none()
+    return st.status if st else None
+
+
+def test_a_section_we_mirror_that_says_0_keeps_its_rows_and_does_not_hold_up_the_rest(
+    db, monkeypatch, world
+):
+    # A total of 0 from a section our items come from is a Plex that lost the library for a moment,
+    # not one that un-watched all of it (E32 review round 2): its rows stay. And it is decided per
+    # section: before round 3 one such section (a library emptied on Plex, its mirrored items kept)
+    # made EVERY run incomplete, and un-watches in every other section never synced again.
+    state, rows = world
+    _local_states(state)
+    ep_id = _watched_episode_in_a_shows_section(db)
+    db.commit()
+    out = _run(db, monkeypatch, _FakePlex(_LISTED, more=[("show", [], 0)]))
+    assert _state_of(db, ep_id) == "watched"
+    assert "m1" not in rows()  # the movies section was walked whole: Plex un-watched m1
+    assert out["cleared"] == 1 and out["incomplete"] == 1
+
+
+def test_a_library_the_allowlist_leaves_out_keeps_its_watch_states(db, monkeypatch, world):
+    # Its items are absent from every scan because the scan never walks it — not because Plex
+    # un-watched them. It cleared them on every run (E32 review round 2).
+    state, _rows = world
+    other = PlexLibrary(plex_key="2", title="Shows", kind="show", enabled=True)
+    db.add(other)
+    db.flush()
+    ep = PlexItem(rating_key="e1", library_id=other.id, kind="episode", title="e1")
+    db.add(ep)
+    db.flush()
+    user_id = db.execute(select(PlexLink.user_id)).scalar_one()
+    db.add(PlexState(user_id=user_id, item_id=ep.id, status="watched", synced_to_plex=True))
+    _local_states(state)
+    sysconfig.set_value(db, "plex_libraries", "1")
+    db.commit()
+    out = _run(db, monkeypatch, _FakePlex(_LISTED, more=[("show", [], 0)]))
+    db.expire_all()
+    left = {
+        rk
+        for rk in db.execute(
+            select(PlexItem.rating_key).join(PlexState, PlexState.item_id == PlexItem.id)
+        ).scalars()
+    }
+    assert "m1" not in left  # the walked section still clears
+    kept = db.execute(select(PlexState).where(PlexState.item_id == ep.id)).scalar_one_or_none()
+    assert kept is not None and kept.status == "watched"
+    assert out["cleared"] == 1
+
+
+def test_a_cut_short_section_is_not_rescued_by_a_complete_one_after_it(db, monkeypatch, world):
+    # Each section settles on its own walk: movies cut short (5 said, 3 handed), then a complete
+    # shows listing — m1 may simply not have been reached.
+    state, rows = world
+    _local_states(state)
+    db.commit()
+    shows = [{"ratingKey": "s1"}]
+    out = _run(db, monkeypatch, _FakePlex(_LISTED, total=5, more=[("show", shows, 1)]))
+    assert rows()["m1"] == ("watched", 0, True)
+    assert out["cleared"] == 0 and out["incomplete"] == 1
+
+
+def test_a_listing_without_a_total_is_never_complete(db, monkeypatch, world):
+    state, rows = world
+    _local_states(state)
+    ep_id = _watched_episode_in_a_shows_section(db)
+    db.commit()
+    out = _run(db, monkeypatch, _FakePlex(_LISTED, more=[("show", [], None)]))
+    assert _state_of(db, ep_id) == "watched"  # its section never said how much it holds
+    assert "m1" not in rows()
+    assert out["cleared"] == 1 and out["incomplete"] == 1
+
+
+def test_an_empty_listing_is_not_a_library_of_unwatched_titles(db, monkeypatch, world):
+    state, rows = world
+    state("m1", status="watched", synced_to_plex=True)
+    db.commit()
+    out = _run(db, monkeypatch, _FakePlex([]))
+    assert rows() == {"m1": ("watched", 0, True)}
+    assert out["cleared"] == 0
+
+
+def test_a_dirty_resume_is_re_pushed_as_a_timeline_and_a_dirty_reset_as_an_unscrobble(
+    db, monkeypatch, world
+):
+    state, rows = world
+    state("m1", status="new", position_seconds=300, synced_to_plex=False)
+    state("m2", status="new", position_seconds=2, synced_to_plex=False)  # under the 5 s floor
+    db.commit()
+    plex = _FakePlex([{"ratingKey": rk} for rk in ("m1", "m2", "m3", "m4", "m5")])
+    _run(db, monkeypatch, plex)
+    assert ("timeline", "m1", 300_000) in plex.calls
+    assert ("unscrobble", "m2") in plex.calls
+    assert {rk: synced for rk, (_s, _p, synced) in rows().items()} == {"m1": True, "m2": True}
+
+
+def test_watch_fields_map_to_a_state_only_when_plex_holds_a_signal():
+    to = watch_sync._plex_watch_to_state
+    assert to(None, None, None) is None
+    assert to(0, 4_000, None) is None  # a stray few seconds is not "in progress"
+    assert to(0, 90_000, 1_700_000_000)[:2] == ("new", 90)
+    assert to("2", 90_000, 1_700_000_000)[:2] == ("watched", 0)  # watched wins over an offset

backend/tests/test_reset_link_states.py

@@ -51,7 +51,12 @@ def test_a_link_whose_account_was_deleted_is_reported_dead(client, db, make_user
 
 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/confirm", json={"token": raw, "password": _NEW}
+        ).status_code
+        == 200
+    )
 
     assert client.post("/auth/password-reset/check", json={"token": raw}).json() == {"ok": False}
 

backend/tests/test_response_checked.py

@@ -0,0 +1,58 @@
+"""No test sends a request and throws the response away (E32 S2).
+
+A discarded `client.post(...)` passes whatever it got back. As a SETUP step, a failure leaves the
+test asserting on a state it never reached; as the step UNDER test, the test proves nothing. E32
+found `test_youtube_sources_never_consult_the_guard` passing on a 400 that stopped the request
+before the code it meant to exercise, and 53 more discarded responses across the suite. Each one
+now states the status it expects; this keeps it that way.
+"""
+
+import ast
+from pathlib import Path
+
+TESTS = Path(__file__).resolve().parent
+VERBS = {"get", "post", "put", "patch", "delete", "head", "options", "request"}
+
+
+def discarded_requests(source: str) -> list[int]:
+    """Line numbers of the statements that are a bare request call on an app path."""
+    hits = []
+    for node in ast.walk(ast.parse(source)):
+        if not (isinstance(node, ast.Expr) and isinstance(node.value, ast.Call)):
+            continue
+        func = node.value.func
+        if not (isinstance(func, ast.Attribute) and func.attr in VERBS):
+            continue
+        path = node.value.args[0] if node.value.args else None
+        literal = path.value if isinstance(path, ast.Constant) else None
+        if isinstance(path, ast.JoinedStr):
+            first = path.values[0] if path.values else None
+            literal = first.value if isinstance(first, ast.Constant) else None
+        if isinstance(literal, str) and literal.startswith(("/api", "/auth")):
+            hits.append(node.lineno)
+    return hits
+
+
+def test_the_detector_sees_a_discarded_request_and_passes_a_checked_one():
+    src = (
+        "client.post('/api/x')\n"
+        "client.get(f'/auth/{u}')\n"
+        "assert client.post('/api/x').status_code == 200\n"
+        "r = client.get('/api/y')\n"
+        "items.get('/api/not-a-request-but-a-key')\n"
+    )
+    # The last line is a false positive by design: a dict keyed by an app path is not a thing the
+    # suite does, and a narrower match would miss a client held under any other name.
+    assert discarded_requests(src) == [1, 2, 5]
+
+
+def test_no_test_discards_a_response():
+    offenders = [
+        f"{p.name}:{line}"
+        for p in sorted(TESTS.rglob("test_*.py"))
+        for line in discarded_requests(p.read_text(encoding="utf-8"))
+    ]
+    assert offenders == [], (
+        "assert the status these requests expect (`assert client.post(...).status_code == 200`), "
+        f"or keep the response and check it: {offenders}"
+    )

backend/tests/test_review_round.py

@@ -100,15 +100,22 @@ def test_a_later_registration_never_touches_an_existing_password(db, client, smt
     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"}
+    assert (
+        client.post(
+            "/auth/register", json={"email": "victim@example.com", "password": "the first password"}
+        ).status_code
+        == 200
     )
     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"}
+    assert (
+        client.post(
+            "/auth/register",
+            json={"email": "victim@example.com", "password": "the second password"},
+        ).status_code
+        == 200
     )
 
     db.expire_all()
@@ -116,8 +123,11 @@ def test_a_later_registration_never_touches_an_existing_password(db, client, smt
 
 
 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"}
+    assert (
+        client.post(
+            "/auth/register", json={"email": "victim@example.com", "password": "the first password"}
+        ).status_code
+        == 200
     )
     db.expire_all()
     user = db.execute(select(User).where(User.email == "victim@example.com")).scalar_one()
@@ -126,8 +136,12 @@ def test_a_later_registration_leaves_a_link_already_in_flight_alive(db, client,
     # 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"}
+    assert (
+        client.post(
+            "/auth/register",
+            json={"email": "victim@example.com", "password": "the second password"},
+        ).status_code
+        == 200
     )
 
     db.expire_all()
@@ -148,8 +162,12 @@ def test_a_stripped_account_keeps_its_recovery_stamp(db, client, smtp_on, make_u
         password_revoked_at=datetime.now(timezone.utc),
     )
 
-    client.post(
-        "/auth/register", json={"email": "stripped@example.com", "password": "an attacker password"}
+    assert (
+        client.post(
+            "/auth/register",
+            json={"email": "stripped@example.com", "password": "an attacker password"},
+        ).status_code
+        == 200
     )
 
     db.expire_all()
@@ -169,7 +187,9 @@ def test_a_denied_sibling_is_not_reopened_while_a_pending_row_exists(db, client)
     )
     db.commit()
 
-    client.post("/auth/request-access", json={"email": "pairone@gmail.com"})
+    assert (
+        client.post("/auth/request-access", json={"email": "pairone@gmail.com"}).status_code == 200
+    )
 
     db.expire_all()
     rows = {i.email: i.status for i in db.execute(select(Invite)).scalars().all()}
@@ -195,7 +215,7 @@ def test_an_env_granted_address_cannot_be_shadowed_by_a_stranger(db, client, mon
     # 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 client.post("/auth/request-access", json={"email": "b.ob@gmail.com"}).status_code == 200
 
     assert db.execute(select(Invite)).scalars().all() == []
     assert auth_core.is_allowed(db, "bob@gmail.com") is True
@@ -331,7 +351,12 @@ 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"})
+    assert (
+        client.post(
+            "/auth/request-access", json={"email": "asking@example.com", "lang": "en"}
+        ).status_code
+        == 200
+    )
 
     notices = [w for w in wire if "asking@example.com" in w[1]]
     assert len(notices) == 2

backend/tests/test_saved_views_source.py

@@ -53,8 +53,8 @@ def test_default_is_per_source(db, monkeypatch, override_dep):
     pid = c.post("/api/saved-views", json={"name": "P", "filters": {}, "source": "plex"}).json()[
         "id"
     ]
-    c.patch(f"/api/saved-views/{fid}", json={"is_default": True})
-    c.patch(f"/api/saved-views/{pid}", json={"is_default": True})
+    assert c.patch(f"/api/saved-views/{fid}", json={"is_default": True}).status_code == 200
+    assert c.patch(f"/api/saved-views/{pid}", json={"is_default": True}).status_code == 200
     # Making the Plex view default must NOT clear the feed view's default (different source).
     assert c.get("/api/saved-views?source=feed").json()[0]["is_default"] is True
     assert c.get("/api/saved-views?source=plex").json()[0]["is_default"] is True
@@ -67,3 +67,18 @@ def test_duplicate_name_within_a_source_conflicts(db, monkeypatch, override_dep)
     b = c.post("/api/saved-views", json={"name": "Dup", "filters": {}, "source": "plex"})
     assert a.status_code == 200
     assert b.status_code == 409  # same (user, source, name)
+
+
+def test_a_feed_views_tag_pick_must_be_a_short_list_of_ids(db, monkeypatch, override_dep):
+    """The autotag job reads every view's tag pick (E32 review): the route holds it to the shape the
+    feed sends, on create and on update."""
+    user = _user(db)
+    c = _client(db, user, monkeypatch, override_dep)
+    for bad in (5, "1", [1, "2"], [True], list(range(501))):
+        r = c.post("/api/saved-views", json={"name": "Bad", "filters": {"tags": bad}})
+        assert r.status_code == 422, (bad, r.text)
+    ok = c.post("/api/saved-views", json={"name": "Ok", "filters": {"tags": [1, 2]}})
+    assert ok.status_code == 200, ok.text
+    vid = ok.json()["id"]
+    assert c.patch(f"/api/saved-views/{vid}", json={"filters": {"tags": 5}}).status_code == 422
+    assert c.patch(f"/api/saved-views/{vid}", json={"filters": {"tags": []}}).status_code == 200

backend/tests/test_search_scrape.py

@@ -0,0 +1,178 @@
+"""youtube/search_scrape — the zero-quota InnerTube search (E32 S2: the module was 20% covered).
+
+Everything here breaks silently when YouTube moves: a parser that stops finding videos, a cursor that
+stops paging, a fallback key that outlives its usefulness. The network is an httpx MockTransport.
+"""
+
+import json
+
+import httpx
+import pytest
+
+from app.youtube import search_scrape
+
+RESULTS_HTML = (
+    '<script>{"INNERTUBE_API_KEY":"live-key","INNERTUBE_CLIENT_VERSION":"2.20261001"}</script>'
+)
+
+
+def _video(vid: str, title: str, *, simple: bool = False) -> dict:
+    return {
+        "videoRenderer": {
+            "videoId": vid,
+            "title": {"simpleText": title}
+            if simple
+            else {"runs": [{"text": title[:3]}, {"text": title[3:]}]},
+            "ownerText": {
+                "runs": [
+                    {
+                        "text": "Chan",
+                        "navigationEndpoint": {"browseEndpoint": {"browseId": "UCchan"}},
+                    }
+                ]
+            },
+            "thumbnail": {"thumbnails": [{"url": "small.jpg"}, {"url": "big.jpg"}]},
+        }
+    }
+
+
+PAGE = {
+    "contents": {
+        "sectionListRenderer": {
+            "contents": [
+                {
+                    "itemSectionRenderer": {
+                        "contents": [
+                            _video("v1", "First video"),
+                            {"channelRenderer": {"channelId": "UCx"}},  # not a video: skipped
+                            {
+                                "reelShelfRenderer": {
+                                    "items": [{"reelItemRenderer": {"videoId": "s1"}}]
+                                }
+                            },
+                            _video("v2", "Second", simple=True),
+                            _video("v1", "First video"),  # a repeat in another shelf: once
+                            {"videoRenderer": {"title": {"simpleText": "no id"}}},
+                        ]
+                    }
+                },
+                {
+                    "continuationItemRenderer": {
+                        "continuationEndpoint": {"continuationCommand": {"token": "NEXT"}}
+                    }
+                },
+            ]
+        }
+    }
+}
+
+
+@pytest.fixture
+def net(monkeypatch):
+    """Route every httpx.Client the module opens through a handler the test sets."""
+    calls: list[httpx.Request] = []
+    state: dict = {"handler": None}
+
+    def transport(request: httpx.Request) -> httpx.Response:
+        calls.append(request)
+        return state["handler"](request)
+
+    real = httpx.Client
+    monkeypatch.setattr(
+        search_scrape.httpx,
+        "Client",
+        lambda **kw: real(transport=httpx.MockTransport(transport), **kw),
+    )
+    monkeypatch.setattr(search_scrape, "_config", None)
+    state["calls"] = calls
+    return state
+
+
+def _serve(results_html=RESULTS_HTML, search=PAGE, status=200):
+    def handler(request: httpx.Request) -> httpx.Response:
+        if request.url.path == "/results":
+            if isinstance(results_html, Exception):
+                raise results_html
+            return httpx.Response(200, text=results_html)
+        if isinstance(search, str):
+            return httpx.Response(status, text=search)
+        return httpx.Response(status, json=search)
+
+    return handler
+
+
+def test_a_page_flattens_its_videos_in_order_and_hands_back_the_cursor(net):
+    net["handler"] = _serve()
+    page = search_scrape.search("cats")
+    assert page["next_page_token"] == "NEXT"
+    assert [i["id"] for i in page["items"]] == ["v1", "v2"]
+    assert page["items"][0] == {
+        "id": "v1",
+        "channel_id": "UCchan",
+        "channel_title": "Chan",
+        "title": "First video",
+        "published_at": None,
+        "thumbnail_url": "big.jpg",
+        "live_broadcast": "none",
+    }
+    assert page["items"][1]["title"] == "Second"
+    post = net["calls"][-1]
+    assert post.url.params["key"] == "live-key"
+    body = json.loads(post.content)
+    assert body["query"] == "cats" and body["params"] == search_scrape._TYPE_VIDEO
+    assert body["context"]["client"]["clientVersion"] == "2.20261001"
+
+
+def test_the_next_page_sends_the_cursor_not_the_query_and_the_end_has_none(net):
+    net["handler"] = _serve(search={"onResponseReceivedCommands": [_video("v9", "Last")]})
+    page = search_scrape.search("cats", continuation="NEXT")
+    body = json.loads(net["calls"][-1].content)
+    assert body["continuation"] == "NEXT" and "query" not in body
+    assert [i["id"] for i in page["items"]] == ["v9"]
+    assert page["next_page_token"] is None
+
+
+@pytest.mark.parametrize(
+    ("search", "status"),
+    [
+        ("<html>consent</html>", 200),
+        ({"error": "blocked"}, 429),
+        ({"responseContext": {}, "alerts": ["unusual traffic"]}, 200),
+        ([], 200),
+    ],
+    ids=["not-json", "http-error", "unknown-shape", "not-an-object"],
+)
+def test_a_blocked_or_garbled_answer_is_an_error_not_an_empty_page(net, search, status):
+    net["handler"] = _serve(search=search, status=status)
+    with pytest.raises(search_scrape.ScrapeError):
+        search_scrape.search("cats")
+
+
+def test_a_search_with_no_results_is_an_empty_page_not_an_error(net):
+    net["handler"] = _serve(search={"contents": {"sectionListRenderer": {"contents": []}}})
+    assert search_scrape.search("zzzzqqq") == {"items": [], "next_page_token": None}
+
+
+def test_the_live_key_is_fetched_once_and_cached(net):
+    net["handler"] = _serve()
+    search_scrape.search("a")
+    search_scrape.search("b")
+    assert [c.url.path for c in net["calls"]].count("/results") == 1
+
+
+@pytest.mark.parametrize(
+    "results_html",
+    [httpx.ConnectError("down"), "<html>a consent page, no keys</html>"],
+    ids=["fetch-failed", "no-key-on-page"],
+)
+def test_a_failed_key_fetch_falls_back_for_now_and_tries_again_next_time(net, results_html):
+    """The fallback pair used to be CACHED for the life of the process: one failed fetch pinned
+    every later search to a hard-coded key, and once that went stale search returned nothing,
+    with no error anywhere (E32 S2)."""
+    net["handler"] = _serve(results_html=results_html)
+    search_scrape.search("a")
+    assert net["calls"][-1].url.params["key"] == search_scrape._FALLBACK_KEY
+
+    net["handler"] = _serve()
+    search_scrape.search("b")
+    assert net["calls"][-1].url.params["key"] == "live-key"

backend/tests/test_set_password_link.py

@@ -68,8 +68,12 @@ def test_using_the_link_evicts_whoever_held_the_old_password(db, as_user, make_u
     admin = make_user(role="admin")
     db.commit()
     token = _link(as_user(admin), target.id)
-    client.post(
-        "/auth/password-reset/confirm", json={"token": token, "password": "the owner's own choice"}
+    assert (
+        client.post(
+            "/auth/password-reset/confirm",
+            json={"token": token, "password": "the owner's own choice"},
+        ).status_code
+        == 200
     )
 
     db.refresh(target)

backend/tests/test_shorts_probe.py

@@ -0,0 +1,44 @@
+"""youtube/shorts.probe_is_short — three answers, and the third is not the second (E32 S2: 33% covered).
+
+A Short answers 200 at /shorts/<id>; a regular video redirects to /watch. Anything else — an error
+page, a network failure — is "undetermined, ask again", never "not a Short": that would file a Short
+in the normal feed for good.
+"""
+
+import httpx
+import pytest
+
+from app.youtube import shorts
+
+
+def _client(respond) -> httpx.Client:
+    return httpx.Client(transport=httpx.MockTransport(respond))
+
+
+@pytest.mark.parametrize(
+    ("status", "expected"),
+    [(200, True), (301, False), (302, False), (303, False), (307, False), (308, False)]
+    + [(404, None), (429, None), (500, None)],
+)
+def test_the_status_decides_short_regular_or_undetermined(status, expected):
+    seen: list[httpx.Request] = []
+
+    def respond(request: httpx.Request) -> httpx.Response:
+        seen.append(request)
+        return httpx.Response(status, headers={"location": "https://www.youtube.com/watch?v=x"})
+
+    assert shorts.probe_is_short(_client(respond), "abc123") is expected
+    assert str(seen[0].url) == "https://www.youtube.com/shorts/abc123"
+    assert len(seen) == 1  # a redirect is the answer, never followed
+
+
+def test_a_network_failure_is_undetermined_not_regular():
+    def respond(request: httpx.Request) -> httpx.Response:
+        raise httpx.ConnectTimeout("slow", request=request)
+
+    assert shorts.probe_is_short(_client(respond), "abc123") is None
+
+
+def test_the_client_skips_the_consent_interstitial():
+    with shorts.make_client() as c:
+        assert "SOCS=" in c.headers["cookie"]

backend/tests/test_source_size.py

@@ -0,0 +1,145 @@
+"""The size / complexity RATCHET for the backend (E32, owner 2026-10-03 — "class size" from the quality
+checklist, measured rather than argued). The frontend's twin is src/lib/sourceSize.contract.test.ts.
+
+Two limits, each with today's offenders as a CEILING:
+  * a module over MAX_LINES lines — a listed one may not grow past its line count; any other module
+    may not cross the limit;
+  * a function over ruff's C901 limit (cyclomatic complexity, MAX_COMPLEXITY) — a listed one, by its
+    NAME (`module::function`), may not rise; no other function may cross the limit. (Ranked per
+    module until the E32 review: one function could grow by what another in the same module lost.)
+    A rename reads as a new offender plus a stale entry: move its row.
+Shrinking is free; a module or function that drops UNDER the limit must be taken off its list (red
+until it is), so the lists only get shorter. Raising a ceiling is a decision for the owner, with the
+reason in docs/gates.md.
+
+C901 is measured here rather than switched on in ruff.toml because ruff has no per-function
+baseline: on, it would need a `noqa` on each of today's offenders, and a `noqa` lets the function
+grow without limit. This keeps the ceiling on the number.
+"""
+
+import json
+import re
+import subprocess
+import sys
+from pathlib import Path
+
+BACKEND = Path(__file__).resolve().parent.parent
+MAX_LINES = 800
+MAX_COMPLEXITY = 10  # ruff's C901 default (mccabe max-complexity)
+
+BIG_MODULES: dict[str, int] = {
+    "app/downloads/edit.py": 833,
+    "app/downloads/pipeline.py": 870,
+    "app/logs.py": 839,
+    "app/models.py": 1607,
+    "app/plex/stream.py": 1128,
+    "app/plex/subtitles.py": 1092,
+    "app/routes/admin.py": 864,
+    "app/routes/auth.py": 1353,
+    "app/routes/downloads.py": 1237,
+}
+
+COMPLEX: dict[str, int] = {
+    "app/bodylimit.py::__call__": 11,
+    "app/discover/hero.py::pick": 14,
+    "app/discover/pins.py::_shelf_card": 12,
+    "app/downloads/edit.py::normalize_edit_spec": 16,
+    "app/downloads/edit.py::run_ffmpeg": 15,
+    "app/downloads/formats.py::build_ydl_opts": 11,
+    "app/downloads/gc.py::_sweep_orphan_files": 15,
+    "app/downloads/gc.py::run_download_gc": 11,
+    "app/downloads/og.py::_jpeg_size": 12,
+    "app/downloads/og.py::_watch_tags": 11,
+    "app/downloads/pipeline.py::_download": 14,
+    "app/downloads/pipeline.py::_process_edit": 12,
+    "app/feedquery.py::feed_summary": 14,
+    "app/feedquery.py::filtered_query": 28,
+    "app/plex/query.py::meta_filter_conds": 13,
+    "app/plex/stream.py::start_session": 14,
+    "app/plex/subtitles.py::_ffmpeg_extract": 12,
+    "app/plex/sync.py::sync": 13,
+    "app/plex/tmdb.py::parse_tmdb": 11,
+    "app/plex/watch_sync.py::run_plex_watch_sync": 12,
+    "app/routes/auth.py::callback": 19,
+    "app/routes/debug_sessions.py::send_issue": 12,
+    "app/routes/downloads.py::resolve_source": 11,
+    "app/routes/plex/browse.py::facets": 25,
+    "app/routes/plex/browse.py::per_table": 13,
+    "app/routes/plex/browse.py::unified_library": 18,
+    "app/routes/plex/detail.py::item_detail": 13,
+    "app/routes/search.py::search_youtube": 15,
+    "app/sync/playlists.py::merge_playlist": 19,
+    "app/sync/runner.py::run_rss_poll": 13,
+    "app/sync/tagsuggest.py::compute_tag_suggestions": 14,
+    "app/worker.py::_run_supervised": 18,
+}
+
+
+def _line_counts() -> dict[str, int]:
+    return {
+        p.relative_to(BACKEND).as_posix(): len(p.read_text(encoding="utf-8").split("\n"))
+        for p in sorted((BACKEND / "app").rglob("*.py"))
+    }
+
+
+def _complexity() -> dict[str, int]:
+    """`module::function` -> its complexity; a name taken twice in a module gets ` 2`, ` 3` in
+    source order."""
+    out = subprocess.run(
+        [
+            sys.executable,
+            "-m",
+            "ruff",
+            "check",
+            "--config",
+            str(BACKEND / "ruff.toml"),
+            "--select",
+            "C901",
+            "--output-format",
+            "json",
+            "--exit-zero",
+            str(BACKEND / "app"),
+        ],
+        capture_output=True,
+        text=True,
+        check=True,
+    ).stdout
+    found: dict[str, int] = {}
+    for m in sorted(json.loads(out), key=lambda m: (m["filename"], m["location"]["row"])):
+        value = re.search(r"\((\d+) > \d+\)", m["message"])
+        name = re.search(r"`([^`]+)`", m["message"])
+        assert value and name, m["message"]
+        rel = Path(m["filename"]).resolve().relative_to(BACKEND).as_posix()
+        key, n = f"{rel}::{name.group(1)}", 2
+        while key in found:
+            key, n = f"{rel}::{name.group(1)} {n}", n + 1
+        found[key] = int(value.group(1))
+    return found
+
+
+def test_no_module_crosses_the_line_limit_and_a_listed_one_does_not_grow():
+    over = [
+        f"{f}: {n} lines (ceiling {BIG_MODULES.get(f, MAX_LINES)})"
+        for f, n in _line_counts().items()
+        if n > BIG_MODULES.get(f, MAX_LINES)
+    ]
+    assert over == []
+
+
+def test_lists_no_module_that_is_back_under_the_limit():
+    lines = _line_counts()
+    assert [f for f in BIG_MODULES if lines.get(f, 0) <= MAX_LINES] == []
+
+
+def test_no_function_crosses_the_complexity_limit_and_a_listed_one_does_not_rise():
+    worse = [
+        f"{fn}: {v} (ceiling {COMPLEX.get(fn, MAX_COMPLEXITY)})"
+        for fn, v in _complexity().items()
+        if v > COMPLEX.get(fn, MAX_COMPLEXITY)
+    ]
+    assert worse == []
+
+
+def test_lists_no_function_that_is_back_under_the_limit_or_gone():
+    actual = _complexity()
+    assert [fn for fn in COMPLEX if fn not in actual] == []

backend/tests/test_welcome_mail.py

@@ -229,7 +229,12 @@ def test_registering_again_does_not_create_a_second_account(db, client, monkeypa
     _smtp_on(monkeypatch)
     _capture(monkeypatch, "send_verify_email")
     for _ in range(2):
-        client.post("/auth/register", json={"email": "twice@example.com", "password": _PW})
+        assert (
+            client.post(
+                "/auth/register", json={"email": "twice@example.com", "password": _PW}
+            ).status_code
+            == 200
+        )
 
     db.expire_all()
     rows = db.execute(select(User).where(User.email == "twice@example.com")).scalars().all()

backend/tests/test_youtube_refusals.py

@@ -8,7 +8,9 @@ import httpx
 import pytest
 
 from app.auth import has_read_scope
-from app.models import OAuthToken
+from app.models import Channel, OAuthToken
+from app.sync.explore import explore_ingest_page
+from app.sync.videos import backfill_channel_deep, backfill_channel_recent
 from app.youtube import client as yt
 from app.youtube.client import YouTubeError, refusal_reason
 
@@ -27,12 +29,91 @@ from app.youtube.client import YouTubeError, refusal_reason
         (YouTubeError("No refresh token; user must re-authenticate"), "reconnect"),
         (YouTubeError("m", reason="transport"), "unavailable"),
         (YouTubeError("m", reason="backendError", path="subscriptions"), "unavailable"),
+        # A missing playlist the user never named (a channel's uploads): nothing they can act on.
+        (YouTubeError("m", reason="playlistNotFound", path="playlistItems"), "unavailable"),
+        (YouTubeError("m", reason="emptyAnswer", path="playlistItems"), "unavailable"),
     ],
 )
 def test_a_failure_is_sorted_by_what_the_user_can_do(exc, reason):
     assert refusal_reason(exc) == reason
 
 
+def test_a_missing_playlist_is_gone_only_on_a_route_about_that_playlist():
+    # A playlist deleted on YouTube: neither a retry nor a reconnect helps (it said "reconnect").
+    # Said only where the user picked that one list — anywhere else "this playlist no longer
+    # exists" names nothing on their screen (E32 review round 2).
+    exc = YouTubeError("m", reason="playlistNotFound", path="playlists")
+    assert refusal_reason(exc, playlist=True) == "gone"
+    assert refusal_reason(exc) == "unavailable"
+    assert refusal_reason(YouTubeError("m", reason="quotaExceeded"), playlist=True) == "quota"
+
+
+def test_a_channel_without_uploads_explores_as_an_empty_page():
+    # YouTube answers a channel's uploads playlist as not found when the channel has no uploads.
+    class _Yt:
+        def get_playlist_items(self, *_):
+            raise YouTubeError("m", reason="playlistNotFound", path="playlistItems")
+
+    channel = SimpleNamespace(id="UCempty", uploads_playlist_id="UUempty")
+    assert explore_ingest_page(None, _Yt(), channel) == {"ingested": 0, "next_page_token": None}
+
+
+class _NoUploads:
+    """A client whose every uploads read answers "playlist not found" (a channel with no uploads)."""
+
+    def __init__(self):
+        self.calls = 0
+
+    def get_playlist_items(self, *_):
+        self.calls += 1
+        raise YouTubeError("m", reason="playlistNotFound", path="playlistItems")
+
+
+def test_a_channel_without_uploads_backfills_as_done_and_is_not_charged_again(db):
+    # The recent pass stamped nothing on this answer, so the channel was picked — and charged a
+    # quota unit, with an ERROR traceback — on every backfill run, forever (E32 review round 3).
+    ch = Channel(id="UCempty", title="Empty", uploads_playlist_id="UUempty")
+    db.add(ch)
+    db.commit()
+    yt = _NoUploads()
+    assert backfill_channel_recent(db, yt, ch) == 0
+    db.refresh(ch)
+    assert ch.recent_synced_at is not None and ch.backfill_done and ch.backfill_cursor is None
+    assert backfill_channel_deep(db, yt, ch) == 0
+    assert yt.calls == 1  # the deep pass has nothing left to ask
+
+
+def test_a_deep_backfill_whose_uploads_vanish_ends_instead_of_failing(db):
+    ch = Channel(id="UCgone", title="Gone", uploads_playlist_id="UUgone", backfill_cursor="page2")
+    db.add(ch)
+    db.commit()
+    assert backfill_channel_deep(db, _NoUploads(), ch) == 0
+    db.refresh(ch)
+    assert ch.backfill_done and ch.backfill_cursor is None
+
+
+def test_any_other_backfill_failure_still_raises(db):
+    class _Yt:
+        def get_playlist_items(self, *_):
+            raise YouTubeError("m", reason="quotaExceeded", path="playlistItems")
+
+    ch = Channel(id="UCq", title="Q", uploads_playlist_id="UUq")
+    db.add(ch)
+    db.commit()
+    with pytest.raises(YouTubeError):
+        backfill_channel_recent(db, _Yt(), ch)
+
+
+def test_any_other_explore_failure_still_raises():
+    class _Yt:
+        def get_playlist_items(self, *_):
+            raise YouTubeError("m", reason="quotaExceeded", path="playlistItems")
+
+    channel = SimpleNamespace(id="UCx", uploads_playlist_id="UUx")
+    with pytest.raises(YouTubeError):
+        explore_ingest_page(None, _Yt(), channel)
+
+
 @pytest.mark.parametrize(
     ("route", "target"),
     [

docs/DESIGN.md

@@ -536,8 +536,10 @@ of a full-width panel and nothing on the right.
 ## Dialogs — _Decided_ (C4, built in S3f)
 
 - **Initial focus by purpose** (`Modal`'s required `initialFocus`, so no dialog inherits "the first
-  focusable", which is always the ✕): `field` — a form opens on the body's first control, and one that
-  loads after opening moves the focus there when it arrives, as long as the focus still rests on the ✕;
+  focusable", which is always the ✕): `field` — a form opens on its first field: the body's first
+  control, or the one marked `data-initial-focus` when a control above the form is not one of its
+  fields (the issue composer's Edit / Preview switch); one that loads after opening moves the focus
+  there when it arrives, as long as the focus still rests on the ✕;
   `action` — a confirm, where the least destructive button takes `autoFocus`; `close` — anything to read,
   browse or manage. [WAI-ARIA APG]
 - **The header and the footer are fixed; only the body scrolls,** with the B9 fade at each edge, so the
@@ -702,3 +704,4 @@ of a full-width panel and nothing on the right.
 | 2026-10-01 | E31 Nav rail rows are links                      | Each page row is a real link: a middle-click or Ctrl-click opens the page in a new tab                                                                                                                                                                                                                                 | A button                                                                                                                                                                                               | The owner: open a page in a tab of its own, as on any site                                                                                                                                    |
 | 2026-10-02 | E31 Plex detail second column (refined)          | The facts over the key crew beside the text; the keywords, chips that filter like the genres, under the text; the show page gets all three too                                                                                                                                                                         | All three in the column, as the mockup drew it                                                                                                                                                         | At 20 keywords and 12 crew the column ran to twice the text's height (849 vs ~400 px at 133%): a hole under the text instead of beside it                                                     |
 | 2026-10-02 | E31 Plex detail poster and crew                  | The movie and show poster keeps its 2:3 and grows a rung in a wide hero (w-56 at a 64rem panel); the crew shows its first 6 names and "Show N more" (a list of 8 or fewer shows whole)                                                                                                                                 | Poster stretched to the row; a "More" on the keywords                                                                                                                                                  | The row is as tall as the crew column, so the poster drew ~175×590 and cropped; the crew, not the keywords, set the hero's height                                                             |
+| 2026-10-04 | E32 `field` focus skips a mode switch | A form opens on its first field; a control above it that is not a field (the composer's Edit / Preview) is passed over by marking the field `data-initial-focus` | The first text field everywhere | That moved the focus in the download dialog off its profile choice and in the upload dialog off its drop zone; the mark changes only the form that needs it |

docs/development.md

@@ -39,36 +39,49 @@ decisions and the chosen patterns, rendered with the app's real CSS. It never re
 ## The gate
 
 A change is done when all of this is green. CI runs the same checks server-side
-(`.gitea/workflows/check.yml`), so "main is always green".
+(`.gitea/workflows/check.yml`), so "main is always green". What each gate deliberately does NOT
+check — and why — is the [gate register](gates.md); a test fails when a narrowing is missing from it.
 
 **Backend**
 
 ```bash
-# lint + format check
+# lint + format check (ruff is pinned in backend/requirements-dev.txt)
 python -m ruff check --config backend/ruff.toml backend scripts
 python -m ruff format --check --config backend/ruff.toml backend scripts
 
-# tests — pure-logic + the DB-backed integration lane, against an ephemeral Postgres.
-# The backend tree is bind-mounted, so it always tests your working files.
+# type check — in the test image (requirements.lock does not install on Windows); new errors only,
+# the pre-existing ones are in backend/.basedpyright/baseline.json
+docker compose -f backend/docker-compose.test.yml run --rm --no-deps --build test \
+  python -m basedpyright --project pyrightconfig.json
+
+# tests — pure-logic + the DB-backed integration lane, against an ephemeral Postgres, ending with the
+# coverage total. The backend tree is bind-mounted, so it always tests your working files.
 docker compose -f backend/docker-compose.test.yml up --build --abort-on-container-exit --exit-code-from test
 docker compose -f backend/docker-compose.test.yml down -v
 ```
 
-The test compose sets `SIFTLODE_TEST_REQUIRE_DB=1`, which turns a would-be silent skip (no DB, or no
-ffmpeg) into a hard failure — so the gate can't print green while the DB-backed tests were quietly not
-run. Tests that need a database take the `db` fixture (`backend/tests/conftest.py`); the rest are
-pure-logic and run without one.
+A missing database or ffmpeg is a hard error, not a skip — so the gate can't print green while the
+DB-backed tests were quietly not run (`SIFTLODE_TEST_REQUIRE_DB=0` is the explicit "pure-logic only"
+run for a machine without Postgres). Tests that need a database take the `db` fixture
+(`backend/tests/conftest.py`); the rest are pure-logic and run without one.
 
 **Frontend** (from `frontend/`)
 
 ```bash
+node ../scripts/check-node-modules.mjs   # node_modules == package-lock.json (else: npm ci)
 npm run typecheck     # tsc x3 (app / node / e2e)
-npm run lint          # eslint
+npm run lint          # eslint (typed rules included; warnings fail)
 npm run format:check  # prettier
-npm run knip          # unused exports/deps
-npm run test          # vitest
+npm run knip          # unused files/exports/deps — and unused by what SHIPS (--production)
+npm run test          # vitest (incl. the compiler, size/complexity and gate-register contracts)
+npx vite build        # the production bundle (devOnlyGuard fails it on dev-only code)
 ```
 
+Coverage is reported, never enforced: `npm run test -- --coverage`, and the pytest lane's last line.
+The Playwright suite (`npm run e2e`) runs against the `:8080` stack built from your tree; the release
+requires it. Before an image is pushed, it is scanned with Trivy (HIGH/CRITICAL with a fix fails;
+exceptions in `.trivyignore.yaml`, each with a reason and an expiry).
+
 ## Branching
 
 Trunk-based: branch off `main`, keep the branch gate-green, and land the whole change back to `main`

docs/gates.md

@@ -0,0 +1,136 @@
+# Gate register
+
+Every place a gate deliberately checks **less** than it could: a rule switched off or narrowed for a
+scope, a flag left off, a lane that does not run everywhere, an accepted finding. One row each, with
+the reason and the number measured when the row was written.
+
+**Why this file exists (E32).** The worst defect E32 found was not in any code a reviewer read: a lint
+rule had been switched off with 64 real hits counted in its own comment, and the "false positives"
+beside them were the React Compiler skipping 95 functions without a word. The rule since: **a gate
+with any real hit is never switched off or narrowed** — fix the sites, or suppress each one inline and
+name its invariant. Whatever is left narrowed is listed here, and
+[`frontend/src/lib/gates.contract.test.ts`](../frontend/src/lib/gates.contract.test.ts) reads the
+**effective** configuration and fails when a narrowing is not on this page. A row here is a decision,
+not an oversight; a narrowing missing from here is a test failure.
+
+**The snapshot.** ESLint's effective config for every code file `eslint .` reaches, and the lines
+that run the lanes (`.gitea/workflows/check.yml`, `backend/docker-compose.test.yml`,
+`backend/Dockerfile.test`, the npm scripts, `vitest.config.ts`, `.prettierignore`), are committed in
+[`frontend/src/lib/gates.snapshot.json`](../frontend/src/lib/gates.snapshot.json). The test fails on
+ANY difference — a rule, an option, a glob that moves one file to another config, a new ignore, a CI
+flag. So a change to a gate is always a diff of that file in review, never a shape a detector failed
+to model (E32 review: three rounds of a cleverer detector each found a bypass of the last one's
+fixes). Regenerate it with `GATE_SNAPSHOT=update npx vitest run src/lib/gates.contract.test.ts`
+(from `frontend/`), and read its diff as a gate change: a new file only adds its path; anything else
+needs a reason. A new code file is part of that diff by design.
+
+**How the register is matched:** each narrowing must appear in a table row below as its
+`code-quoted` id, in a row whose **Scope** cell names the scope exactly as the test reports it (a cell
+may list several, separated by ` · `). For ESLint the scopes are the snapshot's config names, and a
+narrowing is read off each config against `src`: a rule at off or warn, or one src applies that a
+scope does not (one id per plugin family), a `no-restricted-*` list that leaves out an entry src's
+declares, an option that lets something through (`allow…`, `ignore…`, `except…`), an unused-disable
+report that is not an error, and a file no config lints. Ruff's TOML is parsed and held to a
+whitelist of key paths, pytest.ini to a whitelist of whole lines.
+
+## ESLint (frontend)
+
+`npm run lint` is `eslint . --max-warnings 0`, so a rule at **warn** fails the lane exactly like an
+error (the test holds that exact script). The warn rows are listed so that claim stays checked.
+A core rule switched off because its typescript-eslint twin replaces it (`no-unused-vars` →
+`@typescript-eslint/no-unused-vars`) is not listed separately; neither are the core rules
+typescript-eslint's compatibility layer switches off for TS files because the type checker reports
+them itself (`no-undef`, `no-redeclare`, `no-dupe-keys`, …), nor the formatting rules
+`eslint-config-prettier` switches off (Prettier owns formatting and has its own lane).
+
+| Scope | Narrowed | Why | Measured |
+| --- | --- | --- | --- |
+| src | `@typescript-eslint/no-unused-vars` — off | tsc owns it (`noUnusedLocals` + `noUnusedParameters` in every project), so a finding is reported once, by one tool. | — |
+| src | `react-hooks/exhaustive-deps` — warn | Preset level; `--max-warnings 0` makes it fail. Every suppression names its invariant (`eslint-comments/require-description`). | 0 suppressions (E32 S4: a suppression of this rule drops the whole function from the React Compiler, so the two that were left went) |
+| src | `react-hooks/incompatible-library` — warn | Preset level; fails under `--max-warnings 0`. VirtualGrid (TanStack Virtual) is the one site, suppressed inline. | 1 |
+| src | `react-hooks/unsupported-syntax` — warn | Preset level; fails under `--max-warnings 0`. | 0 |
+| src | `react-refresh/only-export-components` — warn | Fails under `--max-warnings 0`; `allowConstantExport` lets a module export constants beside its component. | 0 |
+| src | `@typescript-eslint/no-unused-expressions` — narrowed | `allowShortCircuit` + `allowTernary`: `cond && f()` / `a ? f() : g()` side-effect statements are an idiom here. | — |
+| src | `@typescript-eslint/no-floating-promises` — narrowed | `allowForKnownSafeCalls`: React Query's `invalidateQueries`, `refetchQueries`, `cancelQueries`, `resetQueries`, `prefetchQuery`, `prefetchInfiniteQuery` never reject unless asked to (`throwOnError`), so a bare call is safe by name. | 6 names |
+| e2e | `@typescript-eslint/no-floating-promises` — narrowed | The same `allowForKnownSafeCalls` list (the typed rules are one object for both scopes). | 6 names |
+| lib/http.ts | `no-restricted-globals` — narrowed | A network owner (`NETWORK_OWNERS` in eslint.config.js): the one module that may call `fetch` (`send`, which `req` and the public pages go through). Every other network global stays restricted there. | 1 global |
+| lib/api/core.ts | `no-restricted-globals` — narrowed | A network owner: `uploadReq` is the one `XMLHttpRequest` (upload progress). | 1 global |
+| lib/messagesSocket.ts | `no-restricted-globals` — narrowed | A network owner: the chat socket is the one `WebSocket`. | 1 global |
+| src tests · ui tests · lib tests | `no-restricted-globals`, `no-restricted-properties` — off | A test stands a double in for the network (`vi.stubGlobal("fetch", …)`) and may reach it directly. | — |
+| src tests · ui tests · lib tests | `local/literal-a11y-text`, `local/button-primitive`, `local/input-primitive`, `local/surface-role`, `local/glyph-link` — off | A test renders throwaway markup (a raw button as a focus target, an untranslated label) that is not product UI. | — |
+| FocusSafeButton.tsx + AnchoredPopover.tsx | `local/focus-safe-disabled` — off | FocusSafeButton: it IS the focus-safe primitive the rule points everyone else to. | — |
+| FocusSafeButton.tsx + AnchoredPopover.tsx | `local/focus-safe-disabled` — off | AnchoredPopover: the popover's menu row: its native `disabled` is what floating-ui's roving focus reads to skip it. | — |
+| design-lab | `local/literal-a11y-text` — off | The dev-only design lab (never in the bundle — devOnlyGuard fails the build if it is) holds the owner's working copy, not product copy. | — |
+| e2e | `react-hooks/*`, `react-refresh/*`, `local/*`, `no-console`, `no-restricted-globals`, `no-restricted-properties`, `no-restricted-syntax` — not applied | Playwright specs drive a browser from Node: no React, no product UI, and they print to the console on purpose. They get the base + typed rules + the playwright rules. | — |
+| ts configs | `react-hooks/*`, `react-refresh/*`, `local/*`, `no-console`, `no-restricted-globals`, `no-restricted-properties`, `no-restricted-syntax` — not applied | The build configs (vite, vitest, playwright, reactPlugin, devOnlyGuard) run in Node at build time. | — |
+| js configs | `@typescript-eslint/*`, `react-hooks/*`, `react-refresh/*`, `local/*`, `no-console`, `no-restricted-globals`, `no-restricted-properties`, `no-restricted-syntax`, `no-var`, `prefer-const`, `prefer-rest-params`, `prefer-spread`, `no-array-constructor`, `no-unused-expressions` — not applied | `eslint.config.js` and `postcss.config.js`: plain-JS build config, linted with `js.configs.recommended` only. | — |
+| repo scripts | `scripts/*.mjs` — not in the eslint or prettier lane; `js.configs.recommended` + Prettier via `src/lib/repoScripts.contract.test.ts` | They sit at the repo root, and an ESLint config cannot reach past its own directory. The contract test lints and format-checks them from the repo root, to the same bar as the `js configs` row; no typed rules, as they are in no tsc project. | 0 lint hits; 2 files reformatted (E32 review) |
+| everywhere | ignored paths: `dist`, `node_modules`, `playwright-report`, `test-results`, `e2e/.auth` | Build output, installed packages, test artefacts, a live Playwright session. Generated, not written. | — |
+
+**Not enabled** (decided, not forgotten): `strictTypeChecked` — owner decision E32 D3, ~2000 hits with
+none real in the sample; the curated typed pair `no-floating-promises` + `no-deprecated` runs instead.
+
+## TypeScript
+
+| Scope | Narrowed | Why | Measured |
+| --- | --- | --- | --- |
+| config files | `eslint.config.js — not type-checked` | Linted (the `js configs` row) and executed by every lint run, but in no tsc project. Under the node project's `strict` + `checkJs` it reports 43 errors: 42 implicit-`any` parameters in the local rules' visitors (JSX nodes, which ESLint's own `Rule` typings do not model) and one inferred `string` severity. None is a defect; typing them means moving the local rules onto typescript-eslint's `TSESTree` types — a refactor of its own, not done in E32. | 43 (E32 review) |
+| all three projects | `skipLibCheck` | The `.d.ts` of installed packages are not type-checked (ours are). Standard for an app: a package's own types are its maintainers' gate, and checking them costs minutes and reports errors we cannot fix. | — |
+
+Every project has `strict`, `noUncheckedIndexedAccess`, `noUnusedLocals`, `noUnusedParameters` and
+`noFallthroughCasesInSwitch` on; the test fails if one goes off, if a `strict` sub-flag
+(`strictNullChecks`, `noImplicitAny`, …) is set false beside it, if a project gains an `extends`,
+`exclude` or `files`, or if its `include` changes — and a config file at the frontend root that no
+project checks needs a row.
+
+## Ruff (backend + scripts)
+
+| Scope | Narrowed | Why | Measured |
+| --- | --- | --- | --- |
+| backend + scripts | `B008` — narrowed: `fastapi.Depends`, `fastapi.Query` declared immutable | FastAPI's dependency injection IS a call in a default argument, on every route. Every other call in a default still fails. | 474 sites, all of them FastAPI |
+| backend/app | `C901` — not in ruff; measured by `tests/test_source_size.py` | Ruff has no per-function baseline, so turning it on would need a `noqa` per offender, and a `noqa` lets a function grow without limit. The test holds each offender, by name, at its current value. Tests and scripts are outside it: see the size / complexity rows under Lanes. | 32 functions over 10 |
+
+## basedpyright (backend)
+
+| Scope | Narrowed | Why | Measured |
+| --- | --- | --- | --- |
+| backend/app + alembic | `typeCheckingMode` — `standard` | Not `strict`/`all`: those report on every untyped third-party boundary (SQLAlchemy rows, yt-dlp dicts) — thousands of findings, near-zero real ones. `standard` was measured at 7 findings, all fixed (E32 S1). | — |
+| backend/app + alembic | `baseline.json` — pre-existing errors absorbed | The lane fails on NEW errors only; the baseline only shrinks (the lane fails when a run tightens it and it is not committed). Matching is per (file, rule, column span) + count, so burn the hot files first. | 195 entries (E32 S1) |
+| tests/ | not type-checked | A test's job is to fail loudly when wrong — the opposite of the silent runtime failure this lane catches — and annotating fixtures for a checker is churn. | — |
+
+## pytest (backend)
+
+| Scope | Narrowed | Why | Measured |
+| --- | --- | --- | --- |
+| a hand run | `SIFTLODE_TEST_REQUIRE_DB=0` — the DB-backed and ffmpeg tests skip | The explicit "pure-logic only" run for a machine without Postgres. Off by default since E32: without it a missing DB is a hard error; the gate and CI never set it. | — |
+
+## knip (frontend)
+
+| Scope | Narrowed | Why | Measured |
+| --- | --- | --- | --- |
+| --production | `!**/*.testkit.ts!`, `!e2e/**!` | Test kits and the e2e suite are test code: the production pass asks what the SHIPPED code uses. | — |
+| --production | `!reactPlugin.ts!`, `!devOnlyGuard.ts!` | Build tooling the vite config imports: it shapes the bundle but is not in it. | — |
+| --production | `@internal` exports | An export only its test imports says so with a JSDoc `@internal` tag naming the test; knip skips those in production mode. | 35 (E32 S1) |
+
+## Lanes and pipeline
+
+| Scope | Narrowed | Why | Measured |
+| --- | --- | --- | --- |
+| check | e2e (Playwright) not in `check` | It needs the :8080 stack built from the tree (minutes). It runs in `check-full`, and `release` rebuilds the stack and requires it (E32 D2) — nothing ships without it. | 5 specs × 3 engines |
+| CI | no e2e, no Trivy | The lab runner has no browser stack, and Trivy's DB download is not reachable from it. Both run in `release` / `publish` on the dev machine, before anything is pushed. | — |
+| coverage | no threshold | Owner decision E32 D4: reported on both sides, never enforced. "Every regression test seen red" is the bar; a percentage invites tests written to move it. | frontend 80% / backend 78% of lines (E32 S1) |
+| CVE gate | HIGH/CRITICAL with a fix available only | `--ignore-unfixed` + `--severity HIGH,CRITICAL`: a finding with no fix cannot be acted on by an upgrade; it shows in the scan output. A fixable one fails the publish, and the only way past it is `.trivyignore.yaml`. | 0 open (E32 S1) |
+| npm audit (CI) | `--omit=dev --audit-level=high` | What ships to the browser, at high or above. The dev toolchain's advisories were burned down by hand in E32 S1 (18 → 0). | 0 |
+| React Compiler | the functions it skips, pinned | `components/compilerCoverage.contract.test.ts` — the list may only shrink. End state: only VirtualGrid (TanStack Virtual, an IncompatibleLibrary) remains. | 93 (E32 S1) → 29 (E32 S3) → 1, VirtualGrid (E32 S4) |
+| size / complexity | today's offenders as ceilings | `src/lib/sourceSize.contract.test.ts`, `backend/tests/test_source_size.py`: listed files and functions may not grow, nothing new may cross the limit, an entry back under it must be deleted. A function is held by its name, not its rank in the file. | files >800 lines: 13 FE / 9 BE; functions over the limit: 64 FE / 32 BE (E32 review) |
+| size / complexity | shipped code only — not tests, test kits, e2e or `scripts/` | The ratchet guards what runs in production. A test file is long because it is a list of cases, and a test kit is test code; splitting either moves lines without making anything easier to change. `scripts/` is release and seed tooling, not in the image. | outside it: tests >800 lines 2 FE / 5 BE; functions over the limit 2 FE test code (`gates.contract.test.ts` `eslintNarrowings` 23, E32 review round 3; `compilerSkips.testkit.ts` 25), 1 BE test (11), 1 script (`e2e_seed.py` `main` 13) |
+
+## Accepted findings
+
+Entries in `.trivyignore.yaml` (CVE gate) and `--ignore-vuln` flags on CI's `pip-audit` step. Each
+must have a row here (Scope `accepted`) with its reason and its expiry; the test fails on an entry
+without one, and on a `.trivyignore.yaml` entry with no `statement` or no `expired_at`.
+
+| Scope | Finding | Why | Expires |
+| --- | --- | --- | --- |
+| — | none | — | — |

frontend/e2e/helpers.ts

@@ -13,19 +13,24 @@ export async function gotoPage(page: Page, id: string): Promise<void> {
 }
 
 /**
- * Click a channel link that is currently WITHIN the viewport — what a real user does. Never use
- * `.first()` for this after scrolling: the first rendered card lives in the virtualizer's overscan
- * ABOVE the viewport, so Playwright would scroll it into view to click it, moving the scroll
- * position — fatal to any test that then asserts on where the feed was. Returns false if none found.
+ * Click a channel link a real user can actually SEE and hit. Never use `.first()` for this after
+ * scrolling: the first rendered card lives in the virtualizer's overscan ABOVE the viewport, so
+ * Playwright would scroll it into view to click it, moving the scroll position — fatal to any test
+ * that then asserts on where the feed was. Being inside the viewport is not enough either: a card
+ * can sit under the page chrome above the scroller (the update banner, the toolbar band), and the
+ * covered click makes Playwright scroll and retry — the same move (E32 S2: webkit failed 3 in 24).
+ * So the link must be the element hit at its own centre. Returns false if none found.
  */
 export async function clickVisibleChannelLink(page: Page): Promise<boolean> {
   const links = page.getByTestId("video-card-channel").filter({ visible: true });
-  const viewport = page.viewportSize();
-  const height = viewport?.height ?? 800;
   const count = await links.count();
   for (let i = 0; i < count; i++) {
-    const box = await links.nth(i).boundingBox();
-    if (box && box.y >= 0 && box.y + box.height <= height) {
+    const hittable = await links.nth(i).evaluate((el) => {
+      const r = el.getBoundingClientRect();
+      const hit = document.elementFromPoint(r.left + r.width / 2, r.top + r.height / 2);
+      return hit !== null && el.contains(hit);
+    });
+    if (hittable) {
       await links.nth(i).click();
       return true;
     }

frontend/e2e/nav.spec.ts

@@ -6,18 +6,12 @@ import { openApp } from "./helpers";
 // this exercises is precisely what the module-registry refactor replaces.
 test.describe("page switching", () => {
   // Core + admin modules (the E2E account is an admin, matching the real primary user), so this
-  // also exercises the render ternary's admin branches (scheduler / config / users / audit).
-  const RAIL = [
-    "channels",
-    "playlists",
-    "stats",
-    "scheduler",
-    "config",
-    "users",
-    "audit",
-    "settings",
-    "feed",
-  ];
+  // also exercises the admin pages. Since E31 those sit behind ONE rail row ("Administration",
+  // `nav-admin`) that opens a panel of them — the spec still listed them as rail rows of their own,
+  // and it failed on every run from E31 to E32 without anyone seeing it, because e2e was in no
+  // required gate (it is now part of `release`).
+  const RAIL = ["channels", "playlists", "stats", "settings", "feed"];
+  const ADMIN = ["scheduler", "config", "users", "audit"];
 
   test("each rail item activates its page", async ({ page }) => {
     await openApp(page);
@@ -27,6 +21,22 @@ test.describe("page switching", () => {
     }
   });
 
+  test("each admin page opens from the Administration panel and marks it current", async ({
+    page,
+  }) => {
+    await openApp(page);
+    for (const id of ADMIN) {
+      await page.getByTestId("nav-admin").click();
+      await page.getByTestId(`nav-admin-${id}`).click();
+      // The panel closes on a pick; the group row carries the current page…
+      await expect(page.getByTestId("nav-admin")).toHaveAttribute("aria-current", "page");
+      // …and, reopened, the panel marks which one.
+      await page.getByTestId("nav-admin").click();
+      await expect(page.getByTestId(`nav-admin-${id}`)).toHaveAttribute("aria-current", "page");
+      await page.keyboard.press("Escape");
+    }
+  });
+
   test("browser Back steps through visited pages", async ({ page }) => {
     await openApp(page);
 

frontend/e2e/tsconfig.json

@@ -11,6 +11,8 @@
     "noUnusedLocals": true,
     "noUnusedParameters": true,
     "noFallthroughCasesInSwitch": true,
+    // E32: an index read is `T | undefined` here, as it really is (0 errors when switched on).
+    "noUncheckedIndexedAccess": true,
     "esModuleInterop": true,
     "resolveJsonModule": true
   },

frontend/eslint.config.js

@@ -4,16 +4,25 @@ import reactHooks from "eslint-plugin-react-hooks";
 import reactRefresh from "eslint-plugin-react-refresh";
 import prettier from "eslint-config-prettier";
 import globals from "globals";
+import eslintComments from "@eslint-community/eslint-plugin-eslint-comments";
+import vitest from "@vitest/eslint-plugin";
+import playwright from "eslint-plugin-playwright";
 
-// Flat config (ESLint 9). Deliberately NARROW: the high-value rule here is
-// react-hooks/exhaustive-deps — 33 suppressions across the app exist for it, and until this
-// sprint nothing ran to make them mean anything. tsc already owns unused vars, undefined names
+// Flat config (ESLint 9). Deliberately NARROW: the high-value rules here are react-hooks' (the
+// hook rules and the React Compiler's diagnostics). The 33 inline `exhaustive-deps` suppressions this
+// config first met are all gone (0 left, E32 review); what is still suppressed is suppressed inline,
+// one site at a time, each naming its invariant. tsc already owns unused vars, undefined names
 // and types (noUnusedLocals/Parameters + strict), so typescript-eslint's non-type-checked
 // `recommended` is layered on but its overlap with tsc is turned off below to avoid double-reporting
 // and a churny diff. `eslint-config-prettier` is LAST so formatting rules never fight Prettier.
 //
 // reportUnusedDisableDirectives: a `// eslint-disable` that no longer suppresses anything is itself
 // an error — that is what keeps inert disable comments from re-accumulating (the S1b mandate).
+//
+// E32 (gate integrity): every switched-off or narrowed rule here is listed, with its reason and its
+// measured count, in docs/gates.md, and lib/gates.contract.test.ts fails when one is not. A rule
+// with a single real hit is never switched off — its sites are fixed, or each suppressed inline with
+// a `-- <the invariant>` description (eslint-comments/require-description makes that mandatory).
 
 // E22 S4: every way out of the browser goes through the one module that LOGS it — a request line
 // with a request id (lib/http.ts), the upload XHR (lib/api/core.ts), the messages socket
@@ -472,47 +481,103 @@ const SPLIT_CLASS = "/^([a-z][\\w-]*:[\\w\\[!-]|:[a-z\\[!])/";
 const SPLIT_CLASS_MESSAGE =
   "a class split by an interpolation (`${x}hover:…`): Tailwind never sees it whole and emits no CSS; write the class literally (a shared guard is the `act:` variant).";
 
+// Applies to EVERY linted file: a suppression says which rule and why. A bare
+// `eslint-disable-next-line rule` named nothing in four places the E32 audit found, against the
+// CLAUDE.md rule that each one names its invariant; a blanket `eslint-disable` names no rule at all.
+const suppressionRules = {
+  plugins: { "@eslint-community/eslint-comments": eslintComments },
+  linterOptions: { reportUnusedDisableDirectives: "error" },
+  rules: {
+    "@eslint-community/eslint-comments/require-description": ["error", { ignore: [] }],
+    "@eslint-community/eslint-comments/no-unlimited-disable": "error",
+  },
+};
+
+// The two type-aware rules (E32 D3: a curated pair, not strictTypeChecked — ~2000 hits there, none
+// real in the sample). A floating promise is a rejection nobody handles: the audit found two real
+// ones (ChatDock's device key store, VideoEditor's play()). `void` marks a deliberate fire-and-forget
+// whose callee reports its own failure. React Query's invalidate/refetch family never rejects
+// unless asked to (`throwOnError`), so those calls are known-safe by name.
+const typedRules = {
+  "@typescript-eslint/no-floating-promises": [
+    "error",
+    {
+      allowForKnownSafeCalls: [
+        {
+          from: "package",
+          package: "@tanstack/query-core",
+          name: [
+            "invalidateQueries",
+            "refetchQueries",
+            "cancelQueries",
+            "resetQueries",
+            "prefetchQuery",
+            "prefetchInfiniteQuery",
+          ],
+        },
+      ],
+    },
+  ],
+  "@typescript-eslint/no-deprecated": "error",
+};
+
 export default tseslint.config(
   { ignores: ["dist", "node_modules", "playwright-report", "test-results", "e2e/.auth"] },
+  suppressionRules,
   {
     files: ["src/**/*.{ts,tsx}"],
     extends: [js.configs.recommended, ...tseslint.configs.recommended],
     languageOptions: {
       ecmaVersion: 2022,
       globals: { ...globals.browser },
+      parserOptions: { projectService: true, tsconfigRootDir: import.meta.dirname },
     },
     plugins: {
       "react-hooks": reactHooks,
       "react-refresh": reactRefresh,
       local: localRules,
     },
-    linterOptions: {
-      reportUnusedDisableDirectives: "error",
-    },
     rules: {
       ...reactHooks.configs.recommended.rules,
+      ...typedRules,
+      // The React Compiler's own diagnostics that `recommended` leaves out (E32). Each is a function
+      // the compiler SKIPS, silently — `panicThreshold` is "none" and there is no logger, so a lint
+      // error is the only place the skip is said out loud. `todo` is the compiler's "cannot lower
+      // this shape yet" (E32 S4 rewrote all 31 try statements it found); the rest had 0 hits when
+      // switched on. Most are tripwires, but three cannot report anything under
+      // eslint-plugin-react-hooks 7.1.1 (E32 review, read in its source and probed):
+      // `exhaustive-effect-dependencies` (its validation is compiled off — a missing effect dependency
+      // is reported by the classic `exhaustive-deps` only), `memoized-effect-dependencies` (nothing
+      // emits its category) and `rule-suppression` (lint mode hands it no suppression rules, so an
+      // inline disable is never named). They stay on for the plugin version that wires them up; a
+      // function the compiler skips over a suppression is caught by the coverage ratchet below.
+      // `todo` does NOT see every such shape — a conditional, a loop
+      // or an optional call inside a try skips the function with no lint hit at all — so the full
+      // per-function picture is components/compilerCoverage.contract.test.ts.
+      "react-hooks/todo": "error",
+      "react-hooks/memo-dependencies": "error",
+      "react-hooks/rule-suppression": "error",
+      "react-hooks/invariant": "error",
+      "react-hooks/syntax": "error",
+      "react-hooks/void-use-memo": "error",
+      "react-hooks/component-hook-factories": "error",
+      "react-hooks/capitalized-calls": "error",
+      "react-hooks/hooks": "error",
+      "react-hooks/memoized-effect-dependencies": "error",
+      "react-hooks/exhaustive-effect-dependencies": "error",
+      "react-hooks/no-deriving-state-in-effects": "error",
       // eslint-plugin-react-hooks 7's `recommended` is no longer two rules — it carries the whole
-      // React Compiler rule set (E27 S1). On this codebase that landed 283 findings, and they were
-      // triaged rather than bulk-suppressed, because the two answers are different:
+      // React Compiler rule set (E27 S1). On this codebase that landed 283 findings. 66 were fixed or
+      // suppressed inline, each naming its invariant; there is DELIBERATELY no suppressions file — a
+      // bulk `--suppress-all` would hide the next violation instead of answering it.
       //
-      //   react-hooks/refs  217 — OFF, see below.
-      //   the other 66      — real. They went into eslint-suppressions.json as a ratchet for one
-      //                       sprint and E27 S2 burned the file down to nothing: what survives is
-      //                       an inline directive at the site, each naming the invariant it
-      //                       protects. There is DELIBERATELY no suppressions file any more — a
-      //                       bulk `--suppress-all` would hide the next violation instead of
-      //                       answering it, and it cannot hold a warning-level rule anyway.
-      //
-      // `refs` is off because it fires on this app's popover architecture, not on its history, so
-      // suppressing it would not help the next popover anyone writes. Measured over the 217:
-      // 79 are `pop.refs.setReference` / `getReferenceProps` — @floating-ui/react's callback-ref
-      // setters, which are the documented way to use it — and 74 more are passing the popover handle
-      // down as a prop (`popover={pop}`, `ref={fade.ref}`), which is what `components/ui`'s popover
-      // engine is FOR. That is 153 of 217 flagged for having the word `refs` in an object that is not
-      // a React ref. The remaining ~64 are genuine render-phase `someRef.current = x` writes and are
-      // real (E27 S2 answered the ones the other rules could see, at their sites).
-      // Re-evaluate when the rule can: it shipped in 1.0.0 and this looks like over-approximation.
-      "react-hooks/refs": "off",
+      // `refs` (the other 217) was switched OFF in E27 as mostly false positives, and that triage was
+      // wrong: the rule and the React Compiler share one analysis, so every hit was a function the
+      // compiler SKIPS — 21 popover components among them, and Channels' 0.9 s row menu was the bill
+      // (E32). E32 S3–S4 fixed every site (245 measured) instead of narrowing the rule: the popover
+      // engine is read through destructuring, render-phase ref writes became `useEffectEvent` /
+      // `useLatest`. It is on, at error, with no exception.
+      "react-hooks/refs": "error",
       "local/jsx-comment-text": "error",
       "local/focus-safe-disabled": "error",
       "local/button-primitive": "error",
@@ -709,7 +774,12 @@ export default tseslint.config(
     // Tests stand doubles in for the network (`vi.stubGlobal("fetch", …)`) and may reach it directly.
     // …and render throwaway markup whose labels no user ever hears.
     files: ["src/**/*.test.{ts,tsx}"],
+    plugins: { vitest },
     rules: {
+      // A focused test silently skips the rest of the suite; a skipped one is a test nobody runs
+      // (E32 — vitest's allowOnly is on outside CI, so nothing else catches a stray `.only` locally).
+      "vitest/no-focused-tests": "error",
+      "vitest/no-disabled-tests": "error",
       "no-restricted-globals": "off",
       "no-restricted-properties": "off",
       "local/literal-a11y-text": "off",
@@ -720,5 +790,38 @@ export default tseslint.config(
       "local/glyph-link": "off",
     },
   },
+  {
+    // Outside src (E32): the e2e suite and the TypeScript build-tool configs went unlinted — the
+    // flat config named only src/**, so `eslint .` skipped them without a word. The same base and
+    // typed rules as the app; Node globals, since none of it runs in the browser.
+    files: ["e2e/**/*.ts", "*.config.ts", "reactPlugin.ts", "devOnlyGuard.ts"],
+    extends: [js.configs.recommended, ...tseslint.configs.recommended],
+    languageOptions: {
+      ecmaVersion: 2022,
+      globals: { ...globals.node },
+      parserOptions: { projectService: true, tsconfigRootDir: import.meta.dirname },
+    },
+    rules: {
+      ...typedRules,
+      // tsc owns these here too (both tsconfig.node.json and e2e/tsconfig.json are strict +
+      // noUnusedLocals/Parameters).
+      "@typescript-eslint/no-unused-vars": "off",
+      "no-undef": "off",
+    },
+  },
+  {
+    files: ["e2e/**/*.ts"],
+    plugins: { playwright },
+    rules: {
+      "playwright/no-focused-test": "error",
+      "playwright/no-skipped-test": "error",
+    },
+  },
+  {
+    // The two plain-JS configs: this file and postcss's.
+    files: ["*.config.js"],
+    extends: [js.configs.recommended],
+    languageOptions: { ecmaVersion: 2022, sourceType: "module", globals: { ...globals.node } },
+  },
   prettier,
 );

frontend/knip.json

@@ -1,7 +0,0 @@
-{
-  "$schema": "https://unpkg.com/knip@6/schema.json",
-  "playwright": {
-    "config": ["playwright.config.ts"],
-    "entry": ["e2e/**/*.@(spec|setup).ts"]
-  }
-}