refactor: make adapter .tier the single source of truth for ranking

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

worker/lyra_worker/adapters/fakes.py

@@ -31,6 +31,7 @@ class _BaseFake:
                 matched_album=target.album,
                 quality=_QUALITIES.get(self.name, _QUALITIES["youtube"]),
                 track_count=tracks,
+                source_tier=self.tier,
             )
         ]
 

worker/lyra_worker/pipeline.py

@@ -127,7 +127,7 @@ def run_pipeline(
     found: list[Candidate] = []
     for adapter in adapters:
         for c in adapter.search(target):
-            found.append(replace(c, confidence=score_confidence(target, c)))
+            found.append(replace(c, source_tier=adapter.tier, confidence=score_confidence(target, c)))
     _persist_candidates(conn, job_id, found)
 
     # 3. rank

worker/lyra_worker/quality.py

@@ -1,7 +1,5 @@
 from lyra_worker.types import Candidate, Quality
 
-_SOURCE_TIERS = {"qobuz": 0, "soulseek": 1, "youtube": 2}
-
 
 def quality_class(q: Quality) -> int:
     """3 = hi-res lossless, 2 = CD lossless, 1 = lossy."""
@@ -13,11 +11,6 @@ def quality_class(q: Quality) -> int:
     return 1
 
 
-def source_tier(source: str) -> int:
-    """Lower is better. Unknown sources rank worst."""
-    return _SOURCE_TIERS.get(source, 99)
-
-
 def rank_key(c: Candidate) -> tuple[int, int]:
-    """Sort key; larger is better. Quality class first, then source tier."""
-    return (quality_class(c.quality), -source_tier(c.source))
+    """Sort key; larger is better. Quality class first, then source tier (from the adapter)."""
+    return (quality_class(c.quality), -c.source_tier)

worker/lyra_worker/types.py

@@ -26,6 +26,7 @@ class Candidate:
     matched_album: str
     quality: Quality
     track_count: int
+    source_tier: int = 99
     confidence: float = 0.0
 
 

worker/tests/test_quality.py

@@ -1,14 +1,17 @@
-from lyra_worker.quality import quality_class, source_tier, rank_key
+from lyra_worker.quality import quality_class, rank_key
 from lyra_worker.types import Candidate, Quality
 
 HIRES = Quality(fmt="FLAC", lossless=True, bit_depth=24, sample_rate=96000)
 CD = Quality(fmt="FLAC", lossless=True, bit_depth=16, sample_rate=44100)
 MP3 = Quality(fmt="MP3", lossless=False, bitrate_kbps=320)
 
+_TIERS = {"qobuz": 0, "soulseek": 1, "youtube": 2}
+
 
 def _cand(source, quality):
     return Candidate(source=source, source_ref="x", matched_artist="A",
-                     matched_album="B", quality=quality, track_count=10)
+                     matched_album="B", quality=quality, track_count=10,
+                     source_tier=_TIERS[source])
 
 
 def test_quality_class_tiers():
@@ -17,12 +20,6 @@ def test_quality_class_tiers():
     assert quality_class(MP3) == 1
 
 
-def test_source_tier_order():
-    assert source_tier("qobuz") == 0
-    assert source_tier("soulseek") == 1
-    assert source_tier("youtube") == 2
-
-
 def test_design_ranking_order():
     # Qobuz hi-res > Qobuz lossless > Soulseek FLAC > Soulseek MP3 > YouTube
     ordered = [

worker/tests/test_ranker.py

@@ -6,11 +6,14 @@ CD = Quality(fmt="FLAC", lossless=True, bit_depth=16, sample_rate=44100)
 MP3 = Quality(fmt="MP3", lossless=False, bitrate_kbps=320)
 TARGET = MBTarget(artist="Radiohead", album="In Rainbows", track_count=10)
 
+_TIERS = {"qobuz": 0, "soulseek": 1, "youtube": 2}
+
 
 def _cand(source, quality, artist="Radiohead", album="In Rainbows", tracks=10):
     return Candidate(source=source, source_ref=f"{source}:{quality.fmt}",
                      matched_artist=artist, matched_album=album,
-                     quality=quality, track_count=tracks)
+                     quality=quality, track_count=tracks,
+                     source_tier=_TIERS[source])
 
 
 def test_returns_empty_for_no_candidates():