fix: imported FLAC, Ogg and Opus files keep their track and disc numbers (#6171)

The importer wrote track=N/M for every format, which ffmpeg stores in a
Vorbis comment as TRACKNUMBER=3/20; dhowden/tag reads a Vorbis TRACKNUMBER
with a bare Atoi, so it came back 0. All 245 tracks imported since
2026-10-10 (Humanz, Plastic Beach, the Gorillaz super deluxe and twelve
more albums) have no track or disc number, and their album pages have no
order.

- The importer writes a Vorbis track and disc number alone, with
  TRACKTOTAL and DISCTOTAL, as Picard does. ID3 and MP4 keep N/M.
- ReadTrackAndDisc takes the number before a slash when the Vorbis reader
  returns 0, for the scanner and for the import's own check of a download.
- tagReadVersion 6 re-reads the files already held (tag reads only).

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

internal/importer/inspect.go

@@ -133,8 +133,7 @@ func readFile(ctx context.Context, root, path string) File {
 		return f
 	}
 	f.Title, f.Artist, f.AlbumArtist, f.Album = m.Title(), m.Artist(), m.AlbumArtist(), m.Album()
-	f.Track, _ = m.Track()
-	f.Disc, _ = m.Disc()
+	f.Track, f.Disc = library.ReadTrackAndDisc(m)
 	ids := library.ReadTagMBIDs(m)
 	f.GroupMBID, f.ReleaseMBID, f.RecordingMBID = ids.ReleaseGroup, ids.Release, ids.Recording
 	return f

internal/importer/place.go

@@ -38,16 +38,32 @@ type Tags struct {
 // ID3 takes Picard's TXXX descriptions, which ffmpeg writes for any key it
 // has no frame for. MP4's freeform atoms ffmpeg cannot write, so an M4A
 // gets the plain names only.
+//
+// A Vorbis track or disc number is the number alone, its count in
+// TRACKTOTAL and DISCTOTAL, as Picard writes them: dhowden/tag reads
+// TRACKNUMBER "3/20" as 0, and every album imported before #6171 lost its
+// order that way. ID3 and MP4 take "3/20", which their readers parse.
 func (t Tags) args(ext string) []string {
+	vorbis := ext == ".flac" || ext == ".ogg" || ext == ".opus"
+	track, disc := ofN(t.Track, t.Tracks), ofN(t.Disc, t.Discs)
+	if vorbis {
+		track, disc = ofN(t.Track, 0), ofN(t.Disc, 0)
+	}
 	kv := [][2]string{
 		{"title", t.Title}, {"artist", t.Artist}, {"album", t.Album}, {"album_artist", t.AlbumArtist},
-		{"track", ofN(t.Track, t.Tracks)}, {"disc", ofN(t.Disc, t.Discs)},
+		{"track", track}, {"disc", disc},
 	}
 	if t.Year > 0 {
 		kv = append(kv, [2]string{"date", strconv.Itoa(t.Year)})
 	}
 	switch ext {
 	case ".flac", ".ogg", ".opus":
+		if t.Track > 0 && t.Tracks > 0 {
+			kv = append(kv, [2]string{"TRACKTOTAL", strconv.Itoa(t.Tracks)})
+		}
+		if t.Disc > 0 && t.Discs > 0 {
+			kv = append(kv, [2]string{"DISCTOTAL", strconv.Itoa(t.Discs)})
+		}
 		kv = append(kv,
 			[2]string{"MUSICBRAINZ_ALBUMID", t.ReleaseMBID},
 			[2]string{"MUSICBRAINZ_RELEASEGROUPID", t.GroupMBID},

internal/importer/verify_test.go

@@ -212,11 +212,21 @@ func TestTagsArgs(t *testing.T) {
 	tg := Tags{Title: "Get Lucky", Artist: "Daft Punk", Track: 8, Tracks: 13, Disc: 1, Discs: 1, Year: 2013,
 		RecordingMBID: "rec-08", GroupMBID: "rg-ram"}
 	flac := strings.Join(tg.args(".flac"), " ")
-	for _, s := range []string{"title=Get Lucky", "track=8/13", "date=2013", "MUSICBRAINZ_TRACKID=rec-08", "MUSICBRAINZ_RELEASEGROUPID=rg-ram"} {
+	for _, s := range []string{
+		"title=Get Lucky", "track=8 ", "TRACKTOTAL=13", "disc=1 ", "DISCTOTAL=1", "date=2013",
+		"MUSICBRAINZ_TRACKID=rec-08", "MUSICBRAINZ_RELEASEGROUPID=rg-ram",
+	} {
 		if !strings.Contains(flac, s) {
 			t.Errorf("flac args lack %q: %s", s, flac)
 		}
 	}
+	// dhowden/tag reads a Vorbis TRACKNUMBER of "8/13" as 0 (#6171).
+	if strings.Contains(flac, "/13") {
+		t.Errorf("flac track number carries its count: %s", flac)
+	}
+	if mp3 := strings.Join(tg.args(".mp3"), " "); !strings.Contains(mp3, "track=8/13") {
+		t.Errorf("mp3 track should be 8/13, which ID3 readers parse: %s", mp3)
+	}
 	if strings.Contains(flac, "MUSICBRAINZ_ALBUMID") {
 		t.Errorf("an empty release id was written: %s", flac)
 	}

internal/library/mbids_test.go

@@ -242,3 +242,22 @@ func TestReadTagMBIDs_Recording(t *testing.T) {
 		t.Errorf("release track only: recording = %q, want empty", got)
 	}
 }
+
+// A Vorbis TRACKNUMBER of "3/20", as Minstrel's importer wrote it, is track 3
+// (#6171): dhowden/tag reads it as 0.
+func TestReadTrackAndDisc(t *testing.T) {
+	for _, tc := range []struct {
+		name        string
+		m           stubMeta
+		track, disc int
+	}{
+		{"vorbis with counts", stubMeta{format: tag.VORBIS, raw: map[string]interface{}{"tracknumber": "3/20", "discnumber": "2/2"}}, 3, 2},
+		{"vorbis bare", stubMeta{format: tag.VORBIS, raw: map[string]interface{}{"tracknumber": " 7 "}}, 7, 0},
+		{"vorbis junk", stubMeta{format: tag.VORBIS, raw: map[string]interface{}{"tracknumber": "A1", "discnumber": "-1"}}, 0, 0},
+		{"id3 is the library's own reading", stubMeta{format: tag.ID3v2_4, raw: map[string]interface{}{"tracknumber": "3/20"}}, 0, 0},
+	} {
+		if track, disc := ReadTrackAndDisc(tc.m); track != tc.track || disc != tc.disc {
+			t.Errorf("%s: got track %d disc %d, want %d and %d", tc.name, track, disc, tc.track, tc.disc)
+		}
+	}
+}

internal/library/scanner.go

@@ -70,7 +70,11 @@ var audioExtensions = map[string]bool{
 //	   release-track name, so every Vorbis-tagged track came in without its
 //	   tag id and waited on an AcoustID lookup. A re-read stores the tag id,
 //	   over a looked-up one (D4).
-const tagReadVersion int16 = 5
+//	6: a Vorbis TRACKNUMBER or DISCNUMBER written as "3/20" is read (#6171).
+//	   dhowden/tag reads it as 0, and Minstrel's own importer wrote it that
+//	   way, so all 245 FLAC tracks it imported came in with no track or disc
+//	   number and their albums lost their order.
+const tagReadVersion int16 = 6
 
 type Stats struct {
 	Scanned int `json:"scanned"`
@@ -316,8 +320,7 @@ func (s *Scanner) scanFile(
 		return pgtype.UUID{}, false, fmt.Errorf("album: %w", err)
 	}
 
-	trackNum, _ := meta.Track()
-	discNum, _ := meta.Disc()
+	trackNum, discNum := ReadTrackAndDisc(meta)
 
 	// An unchanged file being re-read only to refresh tag-derived columns
 	// doesn't need another ffprobe: the stored duration is still accurate, and

internal/library/tracknumber.go

@@ -0,0 +1,40 @@
+package library
+
+import (
+	"strconv"
+	"strings"
+
+	"github.com/dhowden/tag"
+)
+
+// ReadTrackAndDisc reads a file's track and disc numbers. dhowden/tag reads a
+// Vorbis TRACKNUMBER or DISCNUMBER only as a bare number, but taggers also
+// write "3/20" there (Minstrel's own importer did until #6171), and that
+// reads as 0. For Vorbis the number before the slash is taken instead.
+func ReadTrackAndDisc(m tag.Metadata) (track, disc int) {
+	track, _ = m.Track()
+	disc, _ = m.Disc()
+	if m.Format() != tag.VORBIS {
+		return track, disc
+	}
+	raw := m.Raw()
+	if track == 0 {
+		track = leadingNumber(raw["tracknumber"])
+	}
+	if disc == 0 {
+		disc = leadingNumber(raw["discnumber"])
+	}
+	return track, disc
+}
+
+// leadingNumber is the number in a tag value of "3" or "3/20"; 0 for
+// anything else.
+func leadingNumber(v any) int {
+	s, _ := v.(string)
+	before, _, _ := strings.Cut(s, "/")
+	n, err := strconv.Atoi(strings.TrimSpace(before))
+	if err != nil || n < 0 {
+		return 0
+	}
+	return n
+}