fix(library): a track delete that cannot remove its file deletes nothing — #3918

Two delete paths had opposite failure policies. tracks.RemoveTrack
logged a failed os.Remove and deleted the row anyway, which CASCADEs
likes, plays, playlist memberships and tags, while the file survived
for the next scan to re-import as a stranger. library.DeleteTrackFile
stopped correctly but reported it as a bare 500 nobody could read.

One path now: library.DeleteTrackFile removes the file first and, on
anything but ErrNotExist, returns *FileRemoveError with nothing
deleted. Only then does it delete the row and tidy an emptied album
and artist in one transaction, log the sync change and clear orphaned
artist art. RemoveTrack calls it, which also fixes RemoveTrack never
logging a sync change. Quarantine Delete file now tidies emptied
albums and artists too.

Both endpoints answer an unwritable library (EROFS, EACCES, EPERM) with
409 library_not_writable. The message names the directory (removal
writes to the parent), the uid:gid the server runs as, and that
nothing was deleted. Other remove errors are 500 file_delete_failed
with the path.

The reachable surface is quarantine Delete file, which failed
silently: no copy for the code on either client, and Android swallowed
the exception so the row just reappeared. Web and Android now have
copy for both codes and append the server message for exactly those
two. Android's quarantine screen shows it in a snackbar.

DELETE /api/admin/tracks/{id} has had no client since f7278f24, which
kept it on purpose for a safer admin surface, so its history loss was
latent. Fixed rather than removed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SQ31KQpYbStyK5y58UmPLH

internal/lidarrquarantine/service.go

@@ -35,6 +35,9 @@ var (
 // config changes in lidarrconfig take effect immediately. clientFn returns
 // nil when Lidarr is disabled.
 type Service struct {
+	// dataDir lets a Delete file that empties an artist clear that artist's
+	// cached art, the same as the admin remove-track path.
+	dataDir   string
 	pool      *pgxpool.Pool
 	lidarrCfg *lidarrconfig.Service
 	clientFn  func() *lidarr.Client
@@ -42,11 +45,11 @@ type Service struct {
 
 // NewService constructs a Service. Pass nil for clientFn to disable the
 // Lidarr-using methods (DeleteViaLidarr will return ErrLidarrDisabled).
-func NewService(pool *pgxpool.Pool, cfg *lidarrconfig.Service, clientFn func() *lidarr.Client) *Service {
+func NewService(pool *pgxpool.Pool, cfg *lidarrconfig.Service, clientFn func() *lidarr.Client, dataDir string) *Service {
 	if clientFn == nil {
 		clientFn = func() *lidarr.Client { return nil }
 	}
-	return &Service{pool: pool, lidarrCfg: cfg, clientFn: clientFn}
+	return &Service{pool: pool, lidarrCfg: cfg, clientFn: clientFn, dataDir: dataDir}
 }
 
 // Flag inserts or updates a quarantine row for the caller. Re-flagging
@@ -245,10 +248,13 @@ func (s *Service) snapshot(ctx context.Context, q *dbq.Queries, track dbq.Track)
 	}, nil
 }
 
-// DeleteFile removes the track file from disk and the tracks row, then
-// (via FK ON DELETE CASCADE) clears all per-user quarantine rows for that
-// track and writes an audit row. If the file deletion fails, the per-user
-// rows stay so admin can retry. No partial state.
+// DeleteFile removes the track file from disk and the tracks row (tidying away
+// an album or artist that leaves empty), then — via FK ON DELETE CASCADE —
+// clears every per-user quarantine row for that track and writes an audit row.
+//
+// If the file cannot be removed, nothing is deleted and the per-user rows stay
+// so the admin can retry: the error wraps a *library.FileRemoveError, which the
+// handler turns into an answer naming the cause (#3918). No partial state.
 func (s *Service) DeleteFile(ctx context.Context, trackID, adminID pgtype.UUID) (dbq.LidarrQuarantineAction, error) {
 	q := dbq.New(s.pool)
 	track, err := q.GetTrackByID(ctx, trackID)
@@ -267,7 +273,7 @@ func (s *Service) DeleteFile(ctx context.Context, trackID, adminID pgtype.UUID)
 	if err != nil {
 		return dbq.LidarrQuarantineAction{}, fmt.Errorf("count: %w", err)
 	}
-	if err := library.DeleteTrackFile(ctx, s.pool, trackID); err != nil {
+	if _, err := library.DeleteTrackFile(ctx, s.pool, nil, s.dataDir, trackID); err != nil {
 		return dbq.LidarrQuarantineAction{}, fmt.Errorf("delete file: %w", err)
 	}
 	// tracks row is gone; ON DELETE CASCADE on lidarr_quarantine.track_id

internal/lidarrquarantine/service_test.go

@@ -87,7 +87,7 @@ func TestFlag_HappyPath(t *testing.T) {
 	user := seedUser(t, pool, "alice")
 	track, _, _ := seedTrack(t, pool, "Bad Track", "abc")
 
-	svc := NewService(pool, lidarrconfig.New(pool), nil)
+	svc := NewService(pool, lidarrconfig.New(pool), nil, "")
 	row, err := svc.Flag(context.Background(), user.ID, track.ID, "bad_rip", "crackly")
 	if err != nil {
 		t.Fatalf("Flag: %v", err)
@@ -105,7 +105,7 @@ func TestFlag_UpsertOnSecondFlag(t *testing.T) {
 	user := seedUser(t, pool, "alice")
 	track, _, _ := seedTrack(t, pool, "T", "x")
 
-	svc := NewService(pool, lidarrconfig.New(pool), nil)
+	svc := NewService(pool, lidarrconfig.New(pool), nil, "")
 	if _, err := svc.Flag(context.Background(), user.ID, track.ID, "bad_rip", "first"); err != nil {
 		t.Fatalf("first flag: %v", err)
 	}
@@ -129,7 +129,7 @@ func TestFlag_NonexistentTrackReturnsErrTrackNotFound(t *testing.T) {
 	bogus.Bytes = [16]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}
 	bogus.Valid = true
 
-	svc := NewService(pool, lidarrconfig.New(pool), nil)
+	svc := NewService(pool, lidarrconfig.New(pool), nil, "")
 	_, err := svc.Flag(context.Background(), user.ID, bogus, "bad_rip", "")
 	if !errors.Is(err, ErrTrackNotFound) {
 		t.Errorf("err = %v, want ErrTrackNotFound", err)
@@ -141,7 +141,7 @@ func TestFlag_BadReasonRejected(t *testing.T) {
 	user := seedUser(t, pool, "alice")
 	track, _, _ := seedTrack(t, pool, "T", "x")
 
-	svc := NewService(pool, lidarrconfig.New(pool), nil)
+	svc := NewService(pool, lidarrconfig.New(pool), nil, "")
 	_, err := svc.Flag(context.Background(), user.ID, track.ID, "garbage", "")
 	if !errors.Is(err, ErrBadReason) {
 		t.Errorf("err = %v, want ErrBadReason", err)
@@ -153,7 +153,7 @@ func TestUnflag_DeletesRow(t *testing.T) {
 	user := seedUser(t, pool, "alice")
 	track, _, _ := seedTrack(t, pool, "T", "x")
 
-	svc := NewService(pool, lidarrconfig.New(pool), nil)
+	svc := NewService(pool, lidarrconfig.New(pool), nil, "")
 	if _, err := svc.Flag(context.Background(), user.ID, track.ID, "bad_rip", ""); err != nil {
 		t.Fatalf("Flag: %v", err)
 	}
@@ -171,7 +171,7 @@ func TestListMine_OrderedNewestFirst(t *testing.T) {
 	t1, _, _ := seedTrack(t, pool, "T1", "x")
 	t2, _, _ := seedTrack(t, pool, "T2", "y")
 
-	svc := NewService(pool, lidarrconfig.New(pool), nil)
+	svc := NewService(pool, lidarrconfig.New(pool), nil, "")
 	if _, err := svc.Flag(context.Background(), user.ID, t1.ID, "bad_rip", ""); err != nil {
 		t.Fatalf("Flag t1: %v", err)
 	}
@@ -199,7 +199,7 @@ func TestListAdminQueue_AggregatesByTrackWithReasonCounts(t *testing.T) {
 	carol := seedUser(t, pool, "carol")
 	track, _, _ := seedTrack(t, pool, "Hot Mess", "abc")
 
-	svc := NewService(pool, lidarrconfig.New(pool), nil)
+	svc := NewService(pool, lidarrconfig.New(pool), nil, "")
 	if _, err := svc.Flag(context.Background(), alice.ID, track.ID, "bad_rip", ""); err != nil {
 		t.Fatalf("alice flag: %v", err)
 	}
@@ -235,7 +235,7 @@ func TestResolve_ClearsRowsAndWritesAudit(t *testing.T) {
 	bob := seedUser(t, pool, "bob")
 	track, _, _ := seedTrack(t, pool, "T", "x")
 
-	svc := NewService(pool, lidarrconfig.New(pool), nil)
+	svc := NewService(pool, lidarrconfig.New(pool), nil, "")
 	if _, err := svc.Flag(context.Background(), alice.ID, track.ID, "bad_rip", ""); err != nil {
 		t.Fatalf("alice flag: %v", err)
 	}
@@ -267,7 +267,7 @@ func TestResolve_NoExistingRowsStillWritesAudit(t *testing.T) {
 	user := seedUser(t, pool, "alice")
 	track, _, _ := seedTrack(t, pool, "T", "x")
 
-	svc := NewService(pool, lidarrconfig.New(pool), nil)
+	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 {
@@ -291,7 +291,7 @@ func TestResolve_TrackNotFound(t *testing.T) {
 	bogus.Bytes = [16]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}
 	bogus.Valid = true
 
-	svc := NewService(pool, lidarrconfig.New(pool), nil)
+	svc := NewService(pool, lidarrconfig.New(pool), nil, "")
 	_, err := svc.Resolve(context.Background(), bogus, user.ID)
 	if !errors.Is(err, ErrTrackNotFound) {
 		t.Errorf("err = %v, want ErrTrackNotFound", err)
@@ -315,7 +315,7 @@ func TestDeleteFile_RemovesFileAndAuditsAffected(t *testing.T) {
 		DurationMs: 1000, FilePath: path, FileSize: 1, FileFormat: "mp3",
 	})
 
-	svc := NewService(pool, lidarrconfig.New(pool), nil)
+	svc := NewService(pool, lidarrconfig.New(pool), nil, "")
 	if _, err := svc.Flag(context.Background(), user.ID, track.ID, "bad_rip", ""); err != nil {
 		t.Fatalf("Flag: %v", err)
 	}
@@ -424,7 +424,7 @@ func TestDeleteViaLidarr_LidarrDisabled(t *testing.T) {
 	user := seedUser(t, pool, "alice")
 	track, _, _ := seedTrack(t, pool, "T", "x")
 
-	svc := NewService(pool, lidarrconfig.New(pool), nil)
+	svc := NewService(pool, lidarrconfig.New(pool), nil, "")
 	_, _, err := svc.DeleteViaLidarr(context.Background(), track.ID, user.ID)
 	if !errors.Is(err, ErrLidarrDisabled) {
 		t.Errorf("err = %v, want ErrLidarrDisabled", err)
@@ -499,7 +499,7 @@ func TestDeleteFile_TrackNotFound(t *testing.T) {
 	bogus.Bytes = [16]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}
 	bogus.Valid = true
 
-	svc := NewService(pool, lidarrconfig.New(pool), nil)
+	svc := NewService(pool, lidarrconfig.New(pool), nil, "")
 	_, err := svc.DeleteFile(context.Background(), bogus, user.ID)
 	if !errors.Is(err, ErrTrackNotFound) {
 		t.Errorf("err = %v, want ErrTrackNotFound", err)