fix(worker): parallelize per-source searches in the match phase

Soulseek's slskd search polls up to ~2 min; searching adapters sequentially
added that on top of Qobuz's instant search. Run the per-adapter searches
concurrently via a ThreadPoolExecutor so total match time is the slowest
single source, not their sum. Only Qobuz drives streamrip's shared asyncio
loop and there's one Qobuz adapter, so no two threads use that loop at once.
Results collected in adapter order (map preserves order) for deterministic
candidate ordering; per-adapter failures still swallowed (down source = no
candidates).

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

worker/lyra_worker/pipeline.py

@@ -2,6 +2,7 @@ import os
 import shutil
 import threading
 import time
+from concurrent.futures import ThreadPoolExecutor
 from dataclasses import replace
 from typing import Callable, Sequence
 
@@ -94,6 +95,16 @@ def _poll_download_progress(job_id: str, staging: str, expected: int, stop: "thr
         conn.close()
 
 
+def _search_adapter(adapter: SourceAdapter, target: MBTarget) -> list[Candidate]:
+    """Search one adapter, swallowing failures — a down source contributes no candidates rather
+    than crashing the job. Runs on a worker thread (searches are parallelized across sources)."""
+    try:
+        return list(adapter.search(target))
+    except Exception as e:
+        print(f"pipeline: adapter {adapter.name} search failed: {e}", flush=True)
+        return []
+
+
 def _set_state(conn: psycopg.Connection, job_id: str, state: str, stage: str) -> None:
     with conn.cursor() as cur:
         cur.execute(
@@ -306,15 +317,16 @@ def run_pipeline(
         conn.commit()
         return
 
-    # 2. match — search all adapters; score + persist EVERY candidate found
+    # 2. match — search all adapters CONCURRENTLY (Soulseek's search polls up to ~2 min; run it
+    # alongside Qobuz's instant search so total match time = the slowest source, not their sum).
+    # Only Qobuz touches streamrip's shared asyncio loop and there's a single Qobuz adapter, so no
+    # two threads drive that loop at once. Results are collected in adapter order (map preserves
+    # input order) so candidate ordering stays deterministic.
     _set_state(conn, job_id, "matching", "match")
     found: list[Candidate] = []
-    for adapter in adapters:
-        try:
-            results = adapter.search(target)
-        except Exception as e:  # a down source contributes no candidates, never crashes the job
-            print(f"pipeline: adapter {adapter.name} search failed: {e}", flush=True)
-            continue
+    with ThreadPoolExecutor(max_workers=max(1, len(adapters))) as pool:
+        per_adapter = list(pool.map(lambda a: (a, _search_adapter(a, target)), adapters))
+    for adapter, results in per_adapter:
         for c in results:
             found.append(replace(c, source_tier=adapter.tier, confidence=score_confidence(target, c)))
     _persist_candidates(conn, job_id, found)

worker/tests/test_pipeline.py

@@ -195,6 +195,33 @@ def test_below_threshold_candidates_are_persisted_for_diagnosis(conn):
         assert cur.fetchone()[0] >= 1  # found-but-rejected candidate retained for diagnosis
 
 
+def test_searches_run_concurrently_across_adapters(conn):
+    # Two sources that each take ~0.5s to search must run in parallel: total match time is ~the
+    # slowest single search (~0.5s), not the sum (~1.0s). Also verifies concurrency drops no
+    # candidates — both sources' contributions are persisted.
+    import time as _t
+
+    class _SlowQobuz(FakeQobuz):
+        def search(self, target):
+            _t.sleep(0.5)
+            return super().search(target)
+
+    class _SlowSoulseek(FakeSoulseek):
+        def search(self, target):
+            _t.sleep(0.5)
+            return super().search(target)
+
+    job_id = insert_request(conn, artist="Radiohead", album="In Rainbows")
+    claim_next(conn)
+    start = _t.monotonic()
+    run_pipeline(conn, job_id, [_SlowQobuz(), _SlowSoulseek()], dest_root="/tmp/lib")
+    elapsed = _t.monotonic() - start
+    assert elapsed < 0.9  # concurrent (~0.5s), not sequential (~1.0s)
+    with conn.cursor() as cur:
+        cur.execute('SELECT count(DISTINCT source) FROM "Candidate" WHERE "jobId" = %s', (job_id,))
+        assert cur.fetchone()[0] == 2  # both adapters contributed candidates
+
+
 def test_duplicate_adapter_names_raise(conn):
     import pytest
     from lyra_worker.adapters.fakes import FakeQobuz