# Background
User reported (#534) that the import-modal "Search for Match" dialog
returned irrelevant results when Deezer was the metadata source.
Searching `Dirty White Boy` + `Foreigner` returned 5+ karaoke /
"originally performed by" / "in the style of" / "re-recorded" /
tribute-band results ranked above the actual Foreigner studio cut
from Head Games. User had to scroll past the junk every time, or
fall back to iTunes search which is much slower.
# Root cause — two layers
1. **Endpoint joined `track + artist` into free-text query.**
`/api/deezer/search_tracks` was passing `q=Dirty White Boy Foreigner`
to Deezer's `/search/track` API. Deezer fuzzy-matches that
string across title / lyrics / artist / album / contributors and
orders by global popularity — anything that appears across many
compilations outranks the canonical recording.
2. **No local rerank.** None of the search-modal endpoints applied
any post-filtering. Deezer's API order shipped straight to the
user.
# Fix — same architectural shape Cin would build
## Layer 1: field-scoped query at the client boundary
`core/deezer_client.py::search_tracks()` now accepts optional
`track`, `artist`, `album` kwargs. When provided, builds Deezer's
advanced search syntax: `q=track:"X" artist:"Y" album:"Z"`. Massive
relevance improvement because each term matches the right field
instead of fuzzy-matching everywhere.
Backward compat preserved: legacy free-text `query=` callers still
work unchanged. Field-scoped path takes precedence when both are
provided. Empty input fast-fails without an API call. Embedded
double-quotes stripped (Deezer's syntax has no escape mechanism).
## Layer 2: provider-neutral relevance reranker
New `core/metadata/relevance.py` module — pure-function rerank over
the canonical `Track` dataclass. Composable scoring:
- **Cover/karaoke patterns** (multiplier 0.05, effectively buries):
matches "karaoke", "originally performed by", "in the style of",
"made famous by", "tribute", "vocal version", "backing track",
"cover version", "re-recorded", "cover by", etc. across title,
album, AND artist fields. Catches the screenshot's exact junk:
artist credits like "Pop Music Workshop" / "The Karaoke Channel"
/ "Foreigner Tribute Band".
- **Variant tags** (multiplier 0.4): live / acoustic / demo /
instrumental / remix / radio edit / club mix etc. — softer
penalty since the user MAY want them. Skipped entirely when the
expected_title contains the same tag (so searching
"Track (Live)" still ranks Live versions first).
- **Exact artist boost** (multiplier 1.5): primary artist exactly
matches expected_artist after normalisation. Single strongest
signal for "this is the canonical recording".
- **Title + artist similarity** via SequenceMatcher (parentheticals
+ punctuation stripped before comparison).
- **Album-type weighting**: album=1.0 > single/ep=0.85 > compilation=0.7.
Compilations are more likely tribute / karaoke repackages.
Each component is a standalone function so tests pin them
individually without standing up the full pipeline.
## Wired at three search-modal endpoints
- `/api/deezer/search_tracks` — uses both layers (field-scoped
query + rerank).
- `/api/itunes/search_tracks` — uses rerank only (iTunes API has
no advanced-syntax search, but karaoke / cover variants still
leak through and need the local penalty).
- `/api/spotify/search_tracks` — already builds field-scoped
`track:X artist:Y` query; rerank added as the consistency safety
net so all three sources behave the same from the user's
perspective.
Other Deezer call sites (matching engine, watchlist scanner,
auto-import single-track ID) deliberately not touched in this PR
— they have their own elaborate scoring pipelines tuned to their
specific contexts and aren't surfacing the user-reported issue.
Per Cin: "don't refactor beyond what the task requires."
# Tests
71 new tests across 3 files:
- `tests/metadata/test_relevance.py` (50 tests) — every scoring
component pinned individually + the issue #534 screenshot
reproduced as a regression test (real Foreigner cut wins after
rerank, karaoke variants drop to bottom).
- `tests/metadata/test_deezer_search_query.py` (14 tests) —
advanced-syntax query construction, field-scoped wiring at the
client boundary, free-text path unchanged, kwargs win when
ambiguous, limit clamping, cache key consistency.
- `tests/imports/test_search_match_endpoints.py` (7 tests) —
end-to-end through Flask test client: Deezer endpoint passes
kwargs not joined query; karaoke buried at bottom for all three
sources; legacy query param still works without rerank.
# Verification
- 2441 full suite passes (+71 from baseline 2370)
- 0 failures (the prior watchdog flake fix held)
- Ruff clean across all changed files
- JS parses clean (`node -c webui/static/helper.js`)
# Architectural standards followed
- **Logic at the right boundary.** Query construction lives in the
client (every caller benefits from one change). Rerank lives in
a neutral module (`core/metadata/relevance.py`) over the
canonical `Track` dataclass — works for any source, not Deezer-
specific.
- **Explicit > implicit.** Every scoring rule has its own named
function. Pattern tables are module-level constants tests can
introspect.
- **Scope discipline.** Audited every Deezer search call site;
fixed the user-reported one + the consistent siblings. Did NOT
speculatively normalise every Deezer call across the codebase.
- **Backward compat.** Free-text `query=` callers untouched. Kwargs
added to existing client method signature with safe defaults.
- **Tests pin contract at correct boundary.** Pure-function rerank
tests don't mock anything; client-query tests stub at `_api_get`;
endpoint tests run through the real Flask app.
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