fix(worker): rank Soulseek peers by estimated transfer time, not raw speed

Peer selection ranked (free-slot, advertised-speed, short-queue), ignoring file
size. But Soulseek FLAC rips of one album vary ~2x in size (a 24-bit/bloated rip vs
a standard CD rip) and Lyra scores them the SAME quality class (the slskd search
exposes no bit-depth, so every FLAC is class 2). So a peer advertising high speed
but serving 40MB/track files would out-rank a smaller standard rip that actually
finishes sooner — then blow past the 60-min per-peer backstop, time out, fall
through, and restart at 0% (Linkin Park "Hybrid Theory" looping for hours).

Rank by estimated transfer time instead: album bytes ÷ advertised speed, after the
free-slot check. Prefers whichever peer FINISHES first — fast peers and/or smaller
standard-edition rips — with no quality loss (all class 2). Equal-size case still
reduces to speed order, so existing ranking behaviour is preserved.

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

worker/lyra_worker/adapters/_slskd.py

@@ -72,14 +72,18 @@ def _keep_matching(responses: list, needle: str) -> list:
 
 def _parse_search_responses(responses: list) -> list[dict]:
     """Turn slskd search responses into album candidates (one per peer+directory), ordered so the
-    peers most likely to deliver quickly come first: a free upload slot, then higher upload speed,
-    then a shorter queue. The pipeline tries candidates in this order, so ranking fast/free peers
-    first (over slow or queued ones) is what makes the Soulseek fall-through actually converge.
-    Pure — no I/O — so it is unit-tested offline."""
+    peers that will FINISH first come first: a free upload slot, then the shortest estimated
+    transfer time (album bytes ÷ the peer's advertised speed), then a shorter queue. Ranking on
+    estimated time — not raw speed — matters because Soulseek FLAC rips of the same album vary
+    ~2x in size (a 24-bit/bloated rip vs a standard CD rip), and Lyra scores them the SAME quality
+    class (the search exposes no bit-depth), so a peer advertising high speed but serving huge
+    files can lose a race — and blow past the download backstop — against a peer with a smaller
+    standard rip. The pipeline tries candidates in this order, so this is what makes the Soulseek
+    fall-through converge on a copy that actually completes. Pure — no I/O — unit-tested offline."""
     scored: list[tuple] = []
     for resp in responses:
         username = resp.get("username", "")
-        has_slot = 1 if resp.get("hasFreeUploadSlot") else 0
+        has_slot = 0 if resp.get("hasFreeUploadSlot") else 1  # 0 sorts first (free slot = starts now)
         speed = int(resp.get("uploadSpeed") or 0)
         queue = int(resp.get("queueLength") or 0)
         by_dir: dict[str, list] = {}
@@ -94,6 +98,10 @@ def _parse_search_responses(responses: list) -> list[dict]:
         for directory, dfiles in by_dir.items():
             if not dfiles:
                 continue
+            # Estimated seconds to pull this album from this peer at its advertised rate. Unknown/
+            # zero speed → a low nominal (1 B/s) so total size still orders those peers last.
+            total_bytes = sum(int(f["size"] or 0) for f in dfiles)
+            est_seconds = total_bytes / (speed if speed > 0 else 1)
             lossless = all(f["ext"] in _LOSSLESS_EXT for f in dfiles)
             dirname = _basename(directory)
             if " - " in dirname:
@@ -111,8 +119,9 @@ def _parse_search_responses(responses: list) -> list[dict]:
                 "format": "FLAC" if lossless else "MP3",
                 "bitrate": None,
             }
-            scored.append((has_slot, speed, -queue, candidate))
-    scored.sort(key=lambda t: (t[0], t[1], t[2]), reverse=True)  # free + fast + short-queue first
+            scored.append((has_slot, est_seconds, queue, candidate))
+    # ascending: free slot first, then shortest estimated transfer, then shortest queue
+    scored.sort(key=lambda t: (t[0], t[1], t[2]))
     return [c for *_rest, c in scored]