A sync was upsert-only: a movie/show/season/episode removed from Plex stayed
browsable forever and 404'd on playback. Each section now diffs the rating_keys
it just listed against the stored ones and deletes the stale rows (watch-state /
playlist links cascade via the existing FKs), mirroring the collections prune
that already shipped.
Safety: the prune is GUARDED on a non-empty listing (_prune_stale returns early
when `seen` is empty), so a transient Plex glitch that yields an empty page can
never mass-delete a library — the metadata is cheap to re-sync, an accidental
wipe is the only real risk. Shows prune leaf-first (episodes -> seasons -> shows)
so a stale row is deleted directly before its parent's cascade reaches it.
Out of scope (separate follow-up): library-level reconcile of a whole removed
section + retiring the dead `PlexLibrary.enabled` column.
Tests: movie prune + watch-state cascade, the empty-listing guard (mutation-
verified — removing the guard wipes everything), show/season/episode prune.
351 DB-lane pass, ruff clean.
peter
49011940d6