fix(enrichment): drop the studio tiebreak when the chart is a live take

Follow-through on keeping live recordings for live charts: rank_candidates still
ranked the studio take ahead of a tied live one, so a live chart would auto-match
the studio recording. Skip the studio tiebreak when the source title has a live
marker — duration proximity + score then pick the right live version.

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

lib/mb_match.py

@@ -198,6 +198,11 @@ def rank_candidates(song: dict, candidates: list[dict]) -> list[dict]:
     canonical studio take wins over live/promo/extended cuts. Each returned dict
     is a copy carrying `score` (rounded — it's displayed and stored)."""
     sd = _duration_int(song.get("duration"))
+    # For a chart that IS a live take (build_recording_query keeps live
+    # recordings for these) the studio take is the WRONG recording, so drop the
+    # studio tiebreak — duration proximity + text/mb score then pick the right
+    # live version instead of auto-matching the studio one.
+    prefer_studio = not _LIVE_GROUP_RE.search(str(song.get("title") or ""))
 
     def _dur_diff(c):
         cd = _duration_int(c.get("duration"))
@@ -210,7 +215,7 @@ def rank_candidates(song: dict, candidates: list[dict]) -> list[dict]:
         ranked.append(c)
     ranked.sort(
         key=lambda c: (c["score"],
-                       1 if c.get("studio") else 0,   # canonical studio take
+                       (1 if c.get("studio") else 0) if prefer_studio else 0,
                        -_dur_diff(c),                 # closest to the audio length
                        c.get("mb_score") or 0),
         reverse=True)

tests/test_mb_match.py

@@ -145,6 +145,21 @@ def test_rank_candidates_orders_by_our_score():
     assert all("score" in c for c in ranked)
 
 
+def test_rank_candidates_studio_preference_is_dropped_for_live_charts():
+    """Tied-score candidates: a studio chart prefers the studio take, but a
+    LIVE chart must NOT be forced to the studio recording."""
+    studio = {"recording_id": "studio", "artist": "AC/DC", "title": "Highway to Hell",
+              "studio": True, "mb_score": 90}
+    live = {"recording_id": "live", "artist": "AC/DC", "title": "Highway to Hell",
+            "studio": False, "mb_score": 95}
+    # Studio chart -> studio take wins the tie (studio flag), despite lower mb_score.
+    studio_song = {"artist": "AC/DC", "title": "Highway to Hell"}
+    assert m.rank_candidates(studio_song, [live, studio])[0]["recording_id"] == "studio"
+    # Live chart -> studio preference dropped, so the higher-mb_score live take wins.
+    live_song = {"artist": "AC/DC", "title": "Highway to Hell (Live at Donington)"}
+    assert m.rank_candidates(live_song, [studio, live])[0]["recording_id"] == "live"
+
+
 # ── query building ────────────────────────────────────────────────────────────
 
 def test_build_recording_query_denoises_and_quotes():