fix(lidarrquarantine): keep LidarrAlbumMbid nil on Resolve/DeleteFile audit rows + cover idempotent Resolve

The audit log treats lidarr_album_mbid as a 'this row triggered Lidarr'
marker. Setting it on Resolve/DeleteFile (where Lidarr is never contacted)
muddied that semantic. Reverting to plan: only DeleteViaLidarr writes the
mbid. Adds an idempotency test for Resolve over a track with zero rows
(audit row written, affected_users=0, mbid nil).

internal/lidarrquarantine/service.go

@@ -205,10 +205,13 @@ func (s *Service) Resolve(ctx context.Context, trackID, adminID pgtype.UUID) (db
 	if err := q.DeleteQuarantineForTrack(ctx, trackID); err != nil {
 		return dbq.LidarrQuarantineAction{}, fmt.Errorf("delete rows: %w", err)
 	}
+	// LidarrAlbumMbid stays nil here: Lidarr was not contacted. The audit
+	// log uses the field as a "this row triggered Lidarr" marker, so only
+	// DeleteViaLidarr sets it.
 	return q.WriteQuarantineAction(ctx, dbq.WriteQuarantineActionParams{
 		TrackID: trackID, TrackTitle: snap.TrackTitle, ArtistName: snap.ArtistName,
 		AlbumTitle: snap.AlbumTitle, Action: dbq.LidarrQuarantineActionKindResolved,
-		AdminID: adminID, LidarrAlbumMbid: snap.LidarrAlbumMBID, AffectedUsers: affected,
+		AdminID: adminID, LidarrAlbumMbid: nil, AffectedUsers: affected,
 	})
 }
 
@@ -269,11 +272,12 @@ func (s *Service) DeleteFile(ctx context.Context, trackID, adminID pgtype.UUID)
 	}
 	// tracks row is gone; ON DELETE CASCADE on lidarr_quarantine.track_id
 	// already cleared the per-user rows. We don't call
-	// DeleteQuarantineForTrack separately.
+	// DeleteQuarantineForTrack separately. LidarrAlbumMbid stays nil —
+	// Lidarr was not contacted.
 	return q.WriteQuarantineAction(ctx, dbq.WriteQuarantineActionParams{
 		TrackID: trackID, TrackTitle: snap.TrackTitle, ArtistName: snap.ArtistName,
 		AlbumTitle: snap.AlbumTitle, Action: dbq.LidarrQuarantineActionKindDeletedFile,
-		AdminID: adminID, LidarrAlbumMbid: snap.LidarrAlbumMBID, AffectedUsers: affected,
+		AdminID: adminID, LidarrAlbumMbid: nil, AffectedUsers: affected,
 	})
 }
 

internal/lidarrquarantine/service_test.go

@@ -253,12 +253,37 @@ func TestResolve_ClearsRowsAndWritesAudit(t *testing.T) {
 	if audit.Action != dbq.LidarrQuarantineActionKindResolved {
 		t.Errorf("action = %v, want resolved", audit.Action)
 	}
+	if audit.LidarrAlbumMbid != nil {
+		t.Errorf("lidarr_album_mbid = %v, want nil for resolve", audit.LidarrAlbumMbid)
+	}
 	n, _ := dbq.New(pool).CountQuarantineForTrack(context.Background(), track.ID)
 	if n != 0 {
 		t.Errorf("rows after resolve = %d, want 0", n)
 	}
 }
 
+func TestResolve_NoExistingRowsStillWritesAudit(t *testing.T) {
+	pool := newPool(t)
+	user := seedUser(t, pool, "alice")
+	track, _, _ := seedTrack(t, pool, "T", "x")
+
+	svc := NewService(pool, lidarrconfig.New(pool), nil)
+	// No flags applied — resolve a track with zero quarantine rows.
+	audit, err := svc.Resolve(context.Background(), track.ID, user.ID)
+	if err != nil {
+		t.Fatalf("Resolve: %v", err)
+	}
+	if audit.AffectedUsers != 0 {
+		t.Errorf("affected_users = %d, want 0", audit.AffectedUsers)
+	}
+	if audit.Action != dbq.LidarrQuarantineActionKindResolved {
+		t.Errorf("action = %v, want resolved", audit.Action)
+	}
+	if audit.LidarrAlbumMbid != nil {
+		t.Errorf("lidarr_album_mbid = %v, want nil for resolve", audit.LidarrAlbumMbid)
+	}
+}
+
 func TestResolve_TrackNotFound(t *testing.T) {
 	pool := newPool(t)
 	user := seedUser(t, pool, "alice")
@@ -305,6 +330,9 @@ func TestDeleteFile_RemovesFileAndAuditsAffected(t *testing.T) {
 	if audit.Action != dbq.LidarrQuarantineActionKindDeletedFile {
 		t.Errorf("action = %v, want deleted_file", audit.Action)
 	}
+	if audit.LidarrAlbumMbid != nil {
+		t.Errorf("lidarr_album_mbid = %v, want nil for delete_file", audit.LidarrAlbumMbid)
+	}
 	if _, err := os.Stat(path); !errors.Is(err, os.ErrNotExist) {
 		t.Errorf("file still exists: %v", err)
 	}