S-Bryce reported that for some artists (Vocaloid producers, JP indie
acts, niche Western indie) the artist detail page was missing whole
release-groups visible on musicbrainz.org. Downloaded tracks from
those release-groups appeared in artist track counts but were not
bound to any visible album / single card — orphan "ghost" tracks the
user couldn't browse to.
Two duplicated bugs fed each other:
1. `core/musicbrainz_search.py` browsed MB release-groups with
`release_types=['album', 'ep', 'single']`. MB's primary-type
vocabulary is {Album, Single, EP, Broadcast, Other} — music
videos, one-off web releases, and broadcast singles use Other.
Pre-fix the filter dropped them at the API layer.
2. Three sites duplicated the same "raw primary-type → internal
album_type" mapping with slightly different vocabularies and all
silently defaulted unknown values (including 'Other') to 'album':
core/musicbrainz_search.py `_map_release_type`
core/metadata/types.py inline `{single:single, ep:ep}.get(...)`
core/metadata/cache.py Deezer-specific record_type guard
Letting Other through the filter without a real mapper would have
placed music videos in the Albums view alongside LPs — visually
misleading.
Fix shape:
- New `core/metadata/release_type.py` — single canonical mapper
consumed by every provider's raw→Album projection. Knows the full
MB vocabulary including 'other' and 'broadcast'; routes both into
the singles bucket since they're functionally single-track
releases. Compilation secondary-type override preserved (MB's
canonical Greatest-Hits pattern is `primary=Album,
secondary=[Compilation]`).
- `core/musicbrainz_search.py` `_map_release_type` becomes a thin
alias for the new helper so the six internal call sites stay
intact. API filter gains 'other'.
- `core/metadata/types.py` Album projection drops its inline mini-
mapper and calls the canonical helper. Now also handles the
compilation secondary-type override it was previously missing.
- The Deezer-specific cache.py guard stays as-is — Deezer's
record_type vocabulary is closed (album|single|ep), not affected
by this issue.
Verified end-to-end against MB for S-Bryce's artist (`46196b9c-affa-
4616-b53b-e967c8bd70e0`, inabakumori): pre-fix returned 22 release-
groups; post-fix returns 27, with the 5 extra all landing in the
Singles section with album_type='single' as intended.
23 new unit tests pin the mapper contract (case-insensitive primary
types, compilation secondary override, Other/Broadcast → single,
unknown → album default preserved, defensive empty/None inputs).
2 new tests in test_musicbrainz_search pin the API filter inclusion
of 'other' and the round-trip into the Singles bucket. All 516
existing metadata tests still green — refactor leaves historical
behaviour for {album, ep, single, compilation} unchanged.
987409508b