Backend mutation-hardening cluster from the 2026-07-11 mutation-safety audit
sweep (adversarial-reviewer #22/#23), the parallel-safe backend-isolated slice.
audit#22 F4 — standardize post-commit enqueues on CancellationToken.None:
20 command handlers under MediaCollections/, ProgramSchedules/, Playouts/,
Channels/ threaded the request cancellationToken into work that runs AFTER
SaveChangesAsync commits (WriteAsync rebuild/refresh enqueues, mediator.Publish,
reindex, cache Refresh, and post-commit lookups that gate an enqueue). A late
client-disconnect then turns an already-durable commit into a thrown request AND
drops the side effect. Generalizes the #251 deco-handler fix. Excludes
BuildPlayoutHandler (worker/background token, not a client-disconnect token),
the config/FFmpeg multi-upsert handlers (partial-commit case, separate
follow-up), and response-projection reloads (correctly keep the request token).
audit#22 F2 — DeleteChannelHandler/DeletePlayoutHandler now delete the channel
guide {number}.xml through IFileSystem.File.Delete (observable under
MockFileSystem) and BEFORE the commit (a post-commit delete orphans the xml on a
crash; the xml is regenerable on demand, so pre-commit delete is the safe order).
audit#23 F4 — ReplacePlayoutAlternateScheduleItemsHandler rejects an empty item
list in the handler (not only the controller pre-guard) so a direct caller can't
trip the Max()-on-empty crash.
Docs: api-conventions.md §7a (post-commit token convention + boundaries),
decisions.md entry (rationale, sweep scope, #253 PR2-4 coordination note).
Tests: guide-cache-delete-through-FS for both delete handlers, empty-list guard.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Scan queue handler now returns a QueueLibraryScanResult enum
(Queued|NotFound|SyncDisabled|AlreadyScanning) instead of a lying bool;
LibrariesController.ScanLibrary maps them to 202/404/422/409 with ProblemDetails.
Guard the lock->enqueue with the EnqueueWithTraktLock compensating-unlock pattern.
ScannerService now releases every library/collection lock in a finally so a handler
exception can't leak the lock. Plex "Shows" scheduler batch (one lock, two messages)
now has only the trailing SynchronizePlexNetworks carry the single release
(Unlock flag), mirroring the scheduler Trakt tail-token precedent.
Guard the other lock->enqueue producers (Create/UpdateLocalLibrary, UpdateTraktList)
with compensating unlock. SPA drops the PENDING_GRACE_TICKS heuristic now that the
POST reports 202/409/404/422 directly: 202 -> pending+poll, 409 -> reconcile (no
error toast), 404/422 -> surface error.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
timothyandClaude Opus 4.8