Deep-review round 2 on the round-1 fix:
- Race (medium): the round-1 identity guard did the supersede check and the
respawn in TWO separate _lock sections. A newer same-key session installed in
the gap was still torn down by _spawn's unconditional pop+kill (the round-1
comment even had the direction backwards). Fold the check into _spawn via a
new replace_only= param: the identity test and the pop+replace now share ONE
lock, so the respawn is a true no-op when superseded/culled.
- Honest states (low): the superseded branch returned current_session(key),
which is None when the key was cap-culled during our out-of-lock wait; the
route turns None into a dishonest 'Media file not found on disk' 404 for a
file that exists. Yield 'current_session(key) or s' so a culled session
degrades to the route's retryable 'not available yet' path instead.
- Hygiene: _want_hw docstring corrected (it is a test-only shim now; production
decides via _select_encode) and the two stale _want_hw references refreshed
(stream.py header, config.py plex_transcode_hw).
- tests: the cap-cull no-respawn/no-None sub-case; the _opencl_present except
OSError branch (glob raising, not just empty); tightened a tautological -vf
assertion. Backend gate green (ruff + full pytest).
peter
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