Multi-artist surfaces (home Rediscover, Library Artists tab, Liked
Artists carousel) were all rendering the music-notes placeholder
instead of real artist covers. Root cause:
CachedArtist.toRef() returned an ArtistRef with empty coverUrl —
the cache doesn't store the representative album id the server
derives at query time, and the adapter never reconstructed it.
The artist detail screen worked coincidentally because it derives
its header cover from `artist.albums[0].id` directly rather than
the ArtistRef's coverUrl field.
Fix:
* CachedArtistAdapter.toRef() now accepts an optional coverAlbumId
and reconstructs `/api/albums/<id>/cover` when given. Matches the
pattern AlbumRef uses (deterministic URL from entity id).
* artistTileProvider, libraryArtistsProvider, and artistProvider
(single-artist) each LEFT JOIN cached_albums ordered by sort_title.
First row per artist carries the alphabetically-first album id;
toRef projects that into the cover URL.
* Multi-artist queries dedup in toResult since the join multiplies
rows by album count.
Artists with no albums yet in drift come through with empty
coverUrl — UI falls back to the music-notes placeholder, same
behavior as before for that legitimately-coverless state.
End-to-end pilot of the per-item architecture. Home now reads from
the new homeIndexProvider (drift-first over CachedHomeIndex with
/api/home/index discovery + SWR), then each tile is a small
ConsumerWidget watching its own albumTileProvider/artistTileProvider/
trackTileProvider. Tiles render a matched-dimension skeleton while
their entity is still hydrating, and swap in the real card once
drift emits the populated row.
Track hydration is wired up — /api/tracks/:id already existed so
the queue's case 'track' just calls api.getTrack(id) and persists.
The visible behavior:
* Cold visit: small /api/home/index round-trip (IDs only, ~10×
smaller than /api/home), then sections appear shaped with
skeleton tiles; each tile materializes as the hydration queue
drains. No more "30s blank → everything pops in at once."
* Warm visit: drift index emits instantly, drift entity rows emit
instantly, no network. Page paints fully in the first frame.
* Mid-state: scrolling through a partially-hydrated section sees
real cards next to skeleton cards. Layout doesn't shift because
skeletons match real-card dimensions exactly.
CachedHomeSnapshot (and the legacy homeProvider) stay in place but
unconsumed by Flutter — left in for now so revert is cheap if the
new path needs reworking. Cleanup follow-up in a later slice.
Old /api/home endpoint untouched, so the web client keeps working
unchanged.
Slice A landed with three transitive imports that the analyzer
correctly flagged as unused. AppDb / CachedAlbums table refs
propagate through audio_cache_manager.dart's `show appDbProvider`
re-export chain so the explicit db.dart import in the consumers
is redundant.
Plumbing for the per-item rendering pass — no UI changes yet, just
the layers the home/playlist/liked migrations will sit on.
* CachedHomeIndex drift table (schema 5→6) — section/position →
entity-id rows, populated by the upcoming /api/home/index endpoint.
* HydrationQueue (concurrency=4, in-flight dedup) — bounded request
pump that takes (entityType, entityId) and persists the result to
the right cached_<entity> table. Albums + artists wired today;
tracks deferred until /api/tracks/:id exists.
* Per-entity tile providers (albumTileProvider, artistTileProvider,
trackTileProvider as StreamProvider.family) — watch drift, enqueue
hydration on miss, yield AsyncValue<EntityRef?>.
* Skeleton widgets (album/artist/track) matched to the real card
dimensions with a 1.2s shimmer sweep using FabledSword tokens. No
shimmer-package dep — single AnimationController per surface.
See docs/superpowers/specs/2026-05-13-per-item-rendering-design.md
for the full architecture rationale.
bvandeusen