Deep-review round 5, over round 4's own fixes.
- Sessions are keyed by rating_key alone while a session's DIRECTORY is per (key, offset, tag), and
the artifact URL carried no session identity — so once a seek-restart or a second viewer of the
same item took the registry slot, the old viewer's request for `seg_12.ts` was answered 200 with
the new session's twelfth segment: bytes from a different `-ss` offset under `-copyts`, on a
timeline the client is not on. Wrong content with a success status is the one failure a player
cannot notice, and round 4's reclaim-on-404 could never fire on it. The id is in the path now (so
the playlist's relative names resolve back into the same session), a mismatch is a 404, and the
player reclaims at the playhead. The entry playlist's auto-start is gone with it: it could only
ever begin at 0, silently discarding the viewer's position.
- Round 4 exempted paused viewers from the reaper by keeping EVERY finished session for the full
ten-minute idle window — one whole segmented copy of a film per item, on the volume the download
center shares. The signal it needed already existed: an open player checkpoints its position every
10 s whether or not it is playing, so that route now touches the session and the periodic pass is
back on the short rule.
- POST /session's opportunistic reap was never scoped to the key being started: it walked the whole
registry with the 30 s finished rule, so pressing play on ANY item — even a direct-play one, the
call ran before that early return — killed another viewer's paused session. It is gone; the
periodic pass owns reaping.
- A segment that can never arrive no longer polls out the full 20 s: the producer's handle is passed
to `wait_for`, so a finished ffmpeg answers at once. This is a sync route, so each such wait parked
a threadpool worker AND a pooled DB connection, and an ordinary seek past the produced region was
enough to do it.
- The DataError handler's re-raise branch — the half that keeps a genuine DataError a 500 — is
pinned, so simplifying it to an unconditional 422 cannot pass in silence.
Six regression tests (two route-level, in the DB lane), each mutation-checked red on the assertion
it is named after. pytest 1124, vitest 999.
peter
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