New PlexMediaSourcesController (/api/media-sources/plex) P1-P8 wrapping
existing MediatR commands: state GET, pin-flow, sign-out, per-server
libraries/path-replacements GET+PUT, and refresh — VMs projected to the
S0 shared DTOs, ApiResults mapping, 404 controller pre-checks, #215-style
409 lock guards, [EndpointGroupName("general")].
Lock-lifecycle hardening (the tricky part):
- TryCompletePlexPinFlowHandler now releases the Plex lock ONLY on its
non-handoff exits (timeout-throw, poll exception, enqueue exception, the
dead return-false) via try/catch — NOT an unconditional finally. On
success the lock is handed off to SynchronizePlexMediaSources (the sole
releaser after discovery); a finally would double-release and release
before discovery, re-opening the finding-5 poll race. Fixes the latent
leak where an abandoned pin flow wedged Plex locked until restart.
- StartPlexPinFlow controller compensates UnlockPlex on the Left branch AND
any thrown dispatch/enqueue; only the Right/200 path holds the lock.
- SignOutOfPlexHandler wraps its work in try/finally { UnlockPlex() } — a
terminal handler with no handoff, so unconditional release is correct.
- Post-save library sync enqueues SynchronizePlexLibraryByIdIfNeeded
(Unlock:false) then SynchronizePlexNetworks (Unlock:true) — one lock, one
release on the last message, compensating-unlock if the 2nd enqueue throws
(corrects the Blazor Unlock-ordering bug, finding 6).
Data-integrity hardening:
- UpdatePlexPathReplacementsHandler rejects (422, no mutation) any positive
Id not owned by the route source, blank RemotePath/LocalPath, and null
list/items (findings 2c/8).
- MediaSourceRepository Plex path-replacement UPDATE gains
AND PlexMediaSourceId = @id (Jellyfin/Emby untouched — slice S3).
- ReplaceLibraryPreferences controller validates the id set against the
source's libraries (rejects unowned + Id=0), returns the reloaded list
(ids change on disable).
Tests (NUnit/Shouldly/NSubstitute), 34 new, all green: pin-flow lock
released on thrown-cancellation/poll-throw/enqueue-throw AND held on
success (no double-release); sign-out finally-release under a throwing
dependency; cross-source/nonblank/null path-replacement 422s; library-prefs
id-not-owned 422; post-save enqueue exact messages + Unlock flags; full
controller route/404/409/422 coverage.
Refs #202
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
timothy
