- A failed scan run sends scan_failed. Each failure adds to the count and
the notice shows the latest error. A scan cut short by shutdown says
nothing.
- Marking tracks missing sends tracks_missing with a running count.
- A duplicate sweep that proposes a group it had not proposed before
sends duplicates_found, counting everything awaiting review. A sweep
that only re-finds known groups stays quiet, so a read notice isn't
repeated every sweep (CountDuplicateGroupsDetectedSince).
- A playback-error report sends playback_errors, counting the unresolved
errors (CountUnresolvedPlaybackErrors).
The library package gets its notifier as a package-level SetNotifier
beside SetEventBus, for the same reason the bus is package-level.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
