fix(discover): hide stale singles + replace album set on re-derive

- Client filters the row's album thumbnails to full albums only (hides
  singles/EPs left over from pre-albums-only sweeps).
- Worker: re-deriving an artist deletes its pending album suggestions that are
  no longer picks (stale singles / now-owned), keeping wanted/dismissed rows,
  so the suggestion set self-cleans instead of accumulating.

worker 246, web 189 tests.

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

web/src/app/discover/discover-client.tsx

@@ -36,6 +36,12 @@ function similarTo(seeds: string[]): string | null {
   return `Similar to ${shown}${extra > 0 ? ` +${extra} more` : ""}`;
 }
 
+/** Full-length albums only — hide singles/EPs and secondary-type releases (live/comp) that
+ *  pre-date the albums-only derivation and still linger in the DB. */
+function isFullAlbum(a: Album): boolean {
+  return (a.primaryType ?? "Album") === "Album" && (a.secondaryTypes?.length ?? 0) === 0;
+}
+
 /** Human badge for why an album is surfaced. */
 function badgeFor(reason: string | null): string | null {
   if (reason === "newest") return "Newest";
@@ -214,7 +220,9 @@ export function DiscoverClient() {
         <p className="muted-note">No suggestions yet — run Discover, or follow a few artists to seed it.</p>
       ) : (
         <ul className="list">
-          {rows.map((row) => (
+          {rows.map((row) => {
+            const albums = row.albums.filter(isFullAlbum);
+            return (
             <li key={row.artistMbid} className="list-row disco-row">
               <div className="main">
                 <div className="rtitle">
@@ -230,9 +238,9 @@ export function DiscoverClient() {
                 {similarTo(row.seeds) ? <div className="rmeta why">{similarTo(row.seeds)}</div> : null}
               </div>
 
-              {row.albums.length > 0 ? (
+              {albums.length > 0 ? (
                 <div className="disco-albums">
-                  {row.albums.map((a) => (
+                  {albums.map((a) => (
                     <div key={a.id} className="disco-album">
                       <button
                         className="disco-thumb"
@@ -264,7 +272,8 @@ export function DiscoverClient() {
                 ) : null}
               </div>
             </li>
-          ))}
+            );
+          })}
         </ul>
       )}
 

worker/lyra_worker/discovery.py

@@ -217,6 +217,16 @@ def _derive_albums(conn: psycopg.Connection, browser: MbBrowser, surfaced: list[
         if popular is not None:
             reasons[popular] = "newest,popular" if reasons.get(popular) == "newest" else "popular"
 
+        # Re-deriving replaces this artist's album set: drop any pending album suggestion of
+        # theirs that is no longer a pick (stale singles/EPs from older sweeps, or an album now
+        # owned), keeping wanted/dismissed rows untouched. Then upsert the current picks.
+        with conn.cursor() as cur:
+            cur.execute(
+                "DELETE FROM \"DiscoverySuggestion\" WHERE kind = 'album' AND status = 'pending' "
+                'AND "artistMbid" = %s AND NOT ("rgMbid" = ANY(%s))',
+                (artist["mbid"], list(reasons.keys())),
+            )
+
         for rg in core:  # preserve newest-first order among the chosen
             reason = reasons.get(rg.rg_mbid)
             if reason is not None:

worker/tests/test_discovery_albums.py

@@ -2,7 +2,7 @@ from lyra_worker.adapters.fakes import FakeMbBrowser, FakeSimilaritySource
 from lyra_worker.browser import ReleaseGroupInfo
 from lyra_worker.discovery import DiscoveryConfig, run_discovery
 from lyra_worker.similarity.base import SimilarArtist
-from tests.conftest import insert_monitored_release, insert_watched_artist
+from tests.conftest import insert_discovery_suggestion, insert_monitored_release, insert_watched_artist
 
 
 def _album_rows(conn):
@@ -92,6 +92,34 @@ def test_popular_matches_by_title_when_lastfm_mbid_missing_and_skips_owned(conn)
     assert _reasons(conn) == {"rg-new": "newest", "rg-match": "popular"}
 
 
+def test_rederiving_replaces_stale_pending_album_suggestions(conn):
+    insert_watched_artist(conn, mbid="s1", name="Seed")
+    # a stale pending album suggestion for c1 that is no longer a pick (e.g. an old single)
+    insert_discovery_suggestion(conn, kind="album", artist_mbid="c1", rg_mbid="rg-old-single",
+                                album="Old Single", status="pending")
+    src = FakeSimilaritySource(similar={"s1": [SimilarArtist("c1", "Cand", 0.9)]})
+    browser = FakeMbBrowser(releases={"c1": [
+        ReleaseGroupInfo("rg-new", "New Album", "Album", (), "2022-01-01"),
+    ]})
+    run_discovery(conn, [src], browser, DiscoveryConfig(albums_per_artist=1))
+    # the stale single is gone; only the freshly-derived album remains
+    assert [r[1] for r in _album_rows(conn)] == ["rg-new"]
+
+
+def test_rederiving_keeps_wanted_album_suggestions(conn):
+    insert_watched_artist(conn, mbid="s1", name="Seed")
+    insert_discovery_suggestion(conn, kind="album", artist_mbid="c1", rg_mbid="rg-wanted",
+                                album="Wanted One", status="wanted")
+    src = FakeSimilaritySource(similar={"s1": [SimilarArtist("c1", "Cand", 0.9)]})
+    browser = FakeMbBrowser(releases={"c1": [
+        ReleaseGroupInfo("rg-new", "New Album", "Album", (), "2022-01-01"),
+    ]})
+    run_discovery(conn, [src], browser, DiscoveryConfig(albums_per_artist=1))
+    with conn.cursor() as cur:  # wanted row untouched (only pending stale rows are replaced)
+        cur.execute('SELECT count(*) FROM "DiscoverySuggestion" WHERE "rgMbid" = %s AND status = \'wanted\'', ("rg-wanted",))
+        assert cur.fetchone()[0] == 1
+
+
 def test_no_popularity_provider_yields_newest_only(conn):
     insert_watched_artist(conn, mbid="s1", name="Seed")
     src = FakeSimilaritySource(similar={"s1": [SimilarArtist("c1", "Cand", 0.9)]})