ingest: rotate recently-played tracks oldest-first when anti-repeat is exhausted

When every candidate is within the anti-repeat window, the fallback replayed
at random, ignoring how long ago each was heard. With a small feed (or a
window larger than a source's pool) this is the *normal* path, and random
picking clusters the same tracks together.

Play the least-recently-heard candidate instead, so tracks rotate at the
widest spacing the pool allows.

- db: add last_played_at(keys) -> key -> most-recent play timestamp.
- providers/listenbrainz: sort the exhausted pool oldest-first.
- scheduler: on exhaustion, return the oldest-played of the drawn candidates
  rather than the last one drawn.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

ingest/radieo/db.py

@@ -79,6 +79,26 @@ class Database:
             ).fetchall()
         return {r["track_key"] for r in rows}
 
+    def last_played_at(self, keys: set[str]) -> dict[str, float]:
+        """Map each of ``keys`` to the timestamp of its most recent play.
+
+        Keys never played are absent from the result (treat as played "at 0",
+        i.e. longest ago). Used by the anti-repeat fallback to play the
+        least-recently-heard candidate instead of a random one when every
+        candidate is within the recent window.
+        """
+        if not keys:
+            return {}
+        placeholders = ",".join("?" * len(keys))
+        with self._lock:
+            rows = self._conn.execute(
+                "SELECT track_key, MAX(played_at) AS last"
+                f" FROM history WHERE track_key IN ({placeholders})"
+                " GROUP BY track_key",
+                tuple(keys),
+            ).fetchall()
+        return {r["track_key"]: r["last"] for r in rows}
+
     def recent_locators(self, limit: int) -> set[str]:
         """Raw backend locators recently played (providers' cheap local filter)."""
         with self._lock:

ingest/radieo/providers/listenbrainz.py

@@ -103,8 +103,16 @@ class ListenBrainzProvider:
         if not recs:
             return None
         recent = self._db.recent_keys(config.ANTIREPEAT_WINDOW)
-        pool = [r for r in recs if f"mbid:{r['mbid']}" not in recent] or list(recs)
-        random.shuffle(pool)
+        fresh = [r for r in recs if f"mbid:{r['mbid']}" not in recent]
+        if fresh:
+            random.shuffle(fresh)  # genuinely unheard recently: order is free
+            pool = fresh
+        else:
+            # Every rec is within the recent window (small feed / large window):
+            # don't replay at random, march through them least-recently-heard
+            # first so each recurs at the widest spacing the feed allows.
+            last = self._db.last_played_at({f"mbid:{r['mbid']}" for r in recs})
+            pool = sorted(recs, key=lambda r: last.get(f"mbid:{r['mbid']}", 0.0))
         for rec in pool:
             track = self._resolve(rec)
             if track is not None:

ingest/radieo/scheduler.py

@@ -34,7 +34,7 @@ class Scheduler:
         if not self._entries:
             return None
         recent = self._db.recent_keys(config.ANTIREPEAT_WINDOW)
-        last = None
+        drawn = []
         for _ in range(config.SCHEDULER_MAX_TRIES):
             track = self._pick()
             if track is None:
@@ -42,10 +42,14 @@ class Scheduler:
             track = self._canonicalizer.canonicalize(track)
             if track.key not in recent:
                 return track
-            last = track  # recently played; try another
+            drawn.append(track)  # recently played; try another
             log.debug("skipping recent %s", track)
-        # Everything drawn was recent (e.g. tiny library): play the last anyway.
-        return last
+        # Every draw was recent (e.g. tiny library): don't just replay the last
+        # one drawn — play whichever of them we've gone longest without hearing.
+        if not drawn:
+            return None
+        last = self._db.last_played_at({t.key for t in drawn})
+        return min(drawn, key=lambda t: last.get(t.key, 0.0))
 
     def _pick(self):
         """Weighted provider draw, falling through to the others when empty."""