diff --git a/backend/.basedpyright/baseline.json b/backend/.basedpyright/baseline.json
index a438d546..5ea56f47 100644
--- a/backend/.basedpyright/baseline.json
+++ b/backend/.basedpyright/baseline.json
@@ -1650,24 +1650,6 @@
                     "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
-                }
             }
         ]
     }
diff --git a/backend/app/bodylimit.py b/backend/app/bodylimit.py
index d2847387..5b4dc3a5 100644
--- a/backend/app/bodylimit.py
+++ b/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
diff --git a/backend/app/downloads/edit.py b/backend/app/downloads/edit.py
index d4967169..24498872 100644
--- a/backend/app/downloads/edit.py
+++ b/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`
diff --git a/backend/app/downloads/runner.py b/backend/app/downloads/runner.py
index ac87b6c1..b609e32e 100644
--- a/backend/app/downloads/runner.py
+++ b/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,
diff --git a/backend/app/feedquery.py b/backend/app/feedquery.py
index f612b8ca..84cfe50f 100644
--- a/backend/app/feedquery.py
+++ b/backend/app/feedquery.py
@@ -438,7 +438,7 @@ 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 +671,8 @@ 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")
diff --git a/backend/app/issues/gitea.py b/backend/app/issues/gitea.py
index 6d462296..b492de71 100644
--- a/backend/app/issues/gitea.py
+++ b/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",
diff --git a/backend/app/logs.py b/backend/app/logs.py
index 64746cf5..d25d5380 100644
--- a/backend/app/logs.py
+++ b/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)
 
 
diff --git a/backend/app/main.py b/backend/app/main.py
index 8f52f23f..a9068e9d 100644
--- a/backend/app/main.py
+++ b/backend/app/main.py
@@ -77,7 +77,7 @@ 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())
diff --git a/backend/app/plex/stream.py b/backend/app/plex/stream.py
index 656dabd9..b25d1e24 100644
--- a/backend/app/plex/stream.py
+++ b/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(",")
diff --git a/backend/app/plex/subtitles.py b/backend/app/plex/subtitles.py
index 22f2a3ce..29059f94 100644
--- a/backend/app/plex/subtitles.py
+++ b/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"
diff --git a/backend/app/plex/sync.py b/backend/app/plex/sync.py
index 90f358b9..1dbd038e 100644
--- a/backend/app/plex/sync.py
+++ b/backend/app/plex/sync.py
@@ -273,7 +273,7 @@ def sync(db: Session) -> dict:
             # 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 +282,7 @@ 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 +296,7 @@ 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
diff --git a/backend/app/progress.py b/backend/app/progress.py
index b6e3f900..98126e7b 100644
--- a/backend/app/progress.py
+++ b/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
diff --git a/backend/app/routes/channels.py b/backend/app/routes/channels.py
index 3f63dfa9..31147bf5 100644
--- a/backend/app/routes/channels.py
+++ b/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}
diff --git a/backend/app/routes/discover.py b/backend/app/routes/discover.py
index 2de01fc8..0d61f99e 100644
--- a/backend/app/routes/discover.py
+++ b/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}
 
diff --git a/backend/app/routes/downloads.py b/backend/app/routes/downloads.py
index af75086e..d9a11554 100644
--- a/backend/app/routes/downloads.py
+++ b/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)
 
 
diff --git a/backend/app/routes/feed.py b/backend/app/routes/feed.py
index 4e905e0c..46c62601 100644
--- a/backend/app/routes/feed.py
+++ b/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")
 
diff --git a/backend/app/routes/playlists.py b/backend/app/routes/playlists.py
index b2e33b51..123ab40b 100644
--- a/backend/app/routes/playlists.py
+++ b/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) 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) 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) 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) 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
diff --git a/backend/app/routes/plex/collections.py b/backend/app/routes/plex/collections.py
index 239c2ed3..0dfdde83 100644
--- a/backend/app/routes/plex/collections.py
+++ b/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)
 
 
diff --git a/backend/app/routes/plex/discover.py b/backend/app/routes/plex/discover.py
index 05d6936b..84c79c96 100644
--- a/backend/app/routes/plex/discover.py
+++ b/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:
diff --git a/backend/app/routes/saved_views.py b/backend/app/routes/saved_views.py
index 6add2507..c400cd0a 100644
--- a/backend/app/routes/saved_views.py
+++ b/backend/app/routes/saved_views.py
@@ -87,7 +87,7 @@ 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)
 
 
@@ -135,7 +135,7 @@ 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)
 
 
diff --git a/backend/app/routes/scheduler.py b/backend/app/routes/scheduler.py
index 2a84dddc..579a691f 100644
--- a/backend/app/routes/scheduler.py
+++ b/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}
diff --git a/backend/app/routes/search.py b/backend/app/routes/search.py
index 31bc2fce..50d284f0 100644
--- a/backend/app/routes/search.py
+++ b/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
diff --git a/backend/app/routes/sync.py b/backend/app/routes/sync.py
index 998d658b..e413c484 100644
--- a/backend/app/routes/sync.py
+++ b/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}
diff --git a/backend/app/routes/tags.py b/backend/app/routes/tags.py
index 7e2c23c9..8228e912 100644
--- a/backend/app/routes/tags.py
+++ b/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,
diff --git a/backend/app/sync/runner.py b/backend/app/sync/runner.py
index b495fbdf..273fb607 100644
--- a/backend/app/sync/runner.py
+++ b/backend/app/sync/runner.py
@@ -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",
diff --git a/backend/app/titles.py b/backend/app/titles.py
index b1e8553f..3e3330cc 100644
--- a/backend/app/titles.py
+++ b/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",
diff --git a/backend/app/worker.py b/backend/app/worker.py
index c5bd2ced..e2006bc9 100644
--- a/backend/app/worker.py
+++ b/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,
diff --git a/backend/app/youtube/client.py b/backend/app/youtube/client.py
index 3439ca5b..8ecacb94 100644
--- a/backend/app/youtube/client.py
+++ b/backend/app/youtube/client.py
@@ -189,7 +189,7 @@ 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
diff --git a/backend/app/youtube/rss.py b/backend/app/youtube/rss.py
index 510bc13d..c8502f89 100644
--- a/backend/app/youtube/rss.py
+++ b/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
 
 
diff --git a/backend/pyrightconfig.json b/backend/pyrightconfig.json
index 6e32135f..e034ee46 100644
--- a/backend/pyrightconfig.json
+++ b/backend/pyrightconfig.json
@@ -25,7 +25,7 @@
 {
   "include": ["app", "alembic"],
   "extraPaths": ["."],
-  "typeCheckingMode": "basic",
+  "typeCheckingMode": "standard",
   "pythonVersion": "3.12",
   "pythonPlatform": "Linux"
 }
diff --git a/backend/pytest.ini b/backend/pytest.ini
index 6692f5b6..f92aa790 100644
--- a/backend/pytest.ini
+++ b/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
diff --git a/backend/ruff.toml b/backend/ruff.toml
index f69ce16c..7778e4ba 100644
--- a/backend/ruff.toml
+++ b/backend/ruff.toml
@@ -29,5 +29,23 @@ 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"]
+#
+# 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",
+]
 ignore = ["E402"]
+
+[lint.flake8-bugbear]
+extend-immutable-calls = ["fastapi.Depends", "fastapi.Query"]
diff --git a/backend/tests/conftest.py b/backend/tests/conftest.py
index c25be444..3c25394f 100644
--- a/backend/tests/conftest.py
+++ b/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."
         )
 
 
diff --git a/backend/tests/test_body_limit.py b/backend/tests/test_body_limit.py
index d967643d..905537e7 100644
--- a/backend/tests/test_body_limit.py
+++ b/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
diff --git a/backend/tests/test_logsink.py b/backend/tests/test_logsink.py
index 7b9eb7cf..f0965c9f 100644
--- a/backend/tests/test_logsink.py
+++ b/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:
diff --git a/backend/tests/test_plex_stream.py b/backend/tests/test_plex_stream.py
index 143f3eb5..22859570 100644
--- a/backend/tests/test_plex_stream.py
+++ b/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
diff --git a/scripts/e2e_seed.py b/scripts/e2e_seed.py
index 975011e4..e1dd85d0 100644
--- a/scripts/e2e_seed.py
+++ b/scripts/e2e_seed.py
@@ -21,10 +21,10 @@ from datetime import datetime, timezone
 
 sys.path.insert(0, "/app")
 
-from sqlalchemy import delete, func, select  # noqa: E402
+from sqlalchemy import delete, func, select
 
-from app.db import SessionLocal  # noqa: E402
-from app.models import (  # noqa: E402
+from app.db import SessionLocal
+from app.models import (
     AppState,
     Channel,
     Playlist,
@@ -34,7 +34,7 @@ from app.models import (  # noqa: E402
     Video,
     VideoState,
 )
-from app.security import hash_password  # noqa: E402
+from app.security import hash_password
 
 EMAIL = os.environ.get("E2E_EMAIL", "e2e@siftlode.local")
 PASSWORD = os.environ.get("E2E_PASSWORD", "")
@@ -171,7 +171,7 @@ def main() -> None:
                 saved = svid.id
         db.commit()
 
-        # noqa T201: this script's stdout IS its interface — the e2e runner parses this JSON.
+        # T201: this script's stdout IS its interface — the e2e runner parses this JSON.
         print(  # noqa: T201
             json.dumps(
                 {