fix: an album with missing tracks is wanted back by its release group, not only when it carries a release MBID (#6167)

The release id was only ever used to find the group. 238 albums matched to a
group carried none, so their losses, five of the resolver's wrong-slot
removals among them, were never fetched again.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/reacquisition/sweeper_test.go

@@ -38,17 +38,21 @@ func newSweepPool(t *testing.T) *pgxpool.Pool {
 }
 
 // lostAlbum seeds an album whose only track has been missing for two days,
-// named by MusicBrainz release id and (when group is set) release group.
+// named by MusicBrainz release id (when release is set) and release group
+// (when group is set).
 func lostAlbum(t *testing.T, pool *pgxpool.Pool, title, release, group string) pgtype.UUID {
 	t.Helper()
 	ctx := context.Background()
 	q := dbq.New(pool)
-	artistMBID := "artist-" + release
+	artistMBID := "artist-" + title
 	ar, err := q.UpsertArtist(ctx, dbq.UpsertArtistParams{Name: title + " Artist", SortName: title, Mbid: &artistMBID})
 	if err != nil {
 		t.Fatal(err)
 	}
-	params := dbq.UpsertAlbumParams{Title: title, SortTitle: title, ArtistID: ar.ID, Mbid: &release}
+	params := dbq.UpsertAlbumParams{Title: title, SortTitle: title, ArtistID: ar.ID}
+	if release != "" {
+		params.Mbid = &release
+	}
 	if group != "" {
 		params.ReleaseGroupMbid = &group
 	}
@@ -58,7 +62,7 @@ func lostAlbum(t *testing.T, pool *pgxpool.Pool, title, release, group string) p
 	}
 	tr, err := q.UpsertTrack(ctx, dbq.UpsertTrackParams{
 		Title: "Lost", AlbumID: al.ID, ArtistID: ar.ID, DurationMs: 180000,
-		FilePath: "/music/" + release + "/01.flac", FileSize: 1, FileFormat: "flac",
+		FilePath: "/music/" + title + "/01.flac", FileSize: 1, FileFormat: "flac",
 	})
 	if err != nil {
 		t.Fatal(err)
@@ -99,7 +103,11 @@ func TestSweep_WantsBackOnlyAlbumsOnTheList_Integration(t *testing.T) {
 	resolved := lostAlbum(t, pool, "Resolved", "release-resolved", "")
 	unknown := lostAlbum(t, pool, "Unknown", "release-unknown", "")
 	_ = lostAlbum(t, pool, "Off The List", "release-off", "group-off")
+	// Matched to a group with no release id: 238 such albums on the operator's
+	// library were never wanted back (#6167).
+	groupOnly := lostAlbum(t, pool, "Group Only", "", "group-only")
 	heldWant(t, pool, "group-tagged", tagged, "3 days")
+	heldWant(t, pool, "group-only", groupOnly, "3 days")
 	heldWant(t, pool, "group-resolved", resolved, "3 days")
 	heldWant(t, pool, "group-unknown", unknown, "3 days")
 
@@ -128,6 +136,7 @@ func TestSweep_WantsBackOnlyAlbumsOnTheList_Integration(t *testing.T) {
 	}
 	wantFor("group-tagged", tagged)
 	wantFor("group-resolved", resolved)
+	wantFor("group-only", groupOnly)
 	if w, _ := q.GetWantByReleaseGroup(ctx, "group-unknown"); !w.FulfilledAt.Valid {
 		t.Error("an album MusicBrainz cannot name was reopened under the wrong group")
 	}