The scan loop called update_album_group_artwork after every successful
track insert, which propagated one track's artwork to every track in
the same group. Tracks with unique embedded covers ended up sharing
whichever cover was processed last. Drop the call; per-track artwork
is resolved correctly by extract_artwork (embedded) + find_folder_artwork
(cover.jpg fallback) before insert_track.
Replace the propagation's caching effect with an in-memory per-folder
HashMap that memoizes find_folder_artwork for the duration of the scan
run, avoiding repeated folder walks for tracks without embedded art.
Mark update_album_group_artwork #[deprecated] so no future caller
reintroduces the bug. Keep it compilable.
Existing libraries already have collapsed artwork paths in the DB and
need a re-scan to recover per-track covers; called out in release notes.
cc
vicrodh
7eba2749f5