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