Three changes folded into one perf+cleanup pass:
1. Indexed fast path for the per-artist pool fetch. The previous
`search_tracks(artist=name)` call hit
`unidecode_lower(artists.name) LIKE ?`, a function-in-WHERE that
can't use `idx_artists_name`. New `MusicDatabase.get_artist_tracks_indexed`
does a two-step lookup: exact-name match (indexed) plus a
case-insensitive fallback, then `tracks WHERE artist_id IN (...)`
via `idx_tracks_artist_id`. Drops per-artist fetch from seconds to
milliseconds for the common case. The sync helper falls back to
the old LIKE-based `search_tracks` only when the indexed lookup
finds nothing, preserving diacritic recall and `tracks.track_artist`
feature-artist matches with zero regression.
2. Public text-normalization helper. Lifted the body of
`MusicDatabase._normalize_for_comparison` into
`core/text/normalize.py:normalize_for_comparison` so callers outside
the database layer (matching engine, sync pool, future import-side
comparisons) don't reach across the module boundary into a
leading-underscore "private" method. The DB method now delegates,
so existing internal call sites stay untouched. Sync's lazy pool
now imports the public helper.
3. Artist-name walker extracted. `_artist_name` at module level in
`services/sync_service.py` replaces two near-identical inline
str-or-dict-or-fallback walkers (one in `sync_playlist`, one in
`_find_track_in_media_server`). Returns `''` for None instead of
the literal string `'None'`.
Plus three small tidies from the same review:
- `_POOL_FETCH_LIMIT = 10000` constant in place of the literal at the
pool-fetch call site.
- Trimmed the verbose docstring + comment block on the pool helper.
- Set-intersection predicate for the trigger-shape reset in
`core/automation/api.py` instead of a two-line `or` chain.
Also removed the duplicate `_get_active_media_client()` call at
sync_service.py:212/214 — pre-existing wart that was sitting in the
same block I was editing.
Tests: 21 new tests across `tests/database/`, `tests/sync/`, and
`tests/text/`, plus updates to the existing pool tests to cover the
new fast/fallback split. Full suite stays green (3953 passing).
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