fix album-level tag consistency for mixed-artist tracks

Use album artist overrides during album ripping so compilation-style tracks do not change album performer tags, and add safer disc-number fallbacks for metadata/path generation when providers omit disc fields.

internal/app/app.go

@@ -39,6 +39,7 @@ type Main struct {
 type ripTrackOptions struct {
 	albumFolder     string
 	albumEmbedCover string
+	albumArtist     string
 	index           int
 	total           int
 	albumDiscTotal  int
@@ -498,7 +499,7 @@ func (m *Main) ripAlbum(ctx context.Context, p provider.Client, source, albumID
 
 	if !m.Config.Session.Downloads.Concurrency || m.Config.Session.Downloads.MaxConnections == 1 {
 		for i, trackID := range trackIDs {
-			opts := ripTrackOptions{albumFolder: folder, albumEmbedCover: artRes.EmbedPath, index: i + 1, total: total, albumDiscTotal: discTotal}
+			opts := ripTrackOptions{albumFolder: folder, albumEmbedCover: artRes.EmbedPath, albumArtist: albumArtist, index: i + 1, total: total, albumDiscTotal: discTotal}
 			if err := m.ripTrack(ctx, p, source, trackID, "", opts); err != nil {
 				failures++
 				m.logf("track failed: id=%s reason=%v\n", trackID, err)
@@ -523,7 +524,7 @@ func (m *Main) ripAlbum(ctx context.Context, p provider.Client, source, albumID
 		go func(idx int, tid string) {
 			defer wg.Done()
 			defer func() { <-sem }()
-			opts := ripTrackOptions{albumFolder: folder, albumEmbedCover: artRes.EmbedPath, index: idx, total: total, albumDiscTotal: discTotal}
+			opts := ripTrackOptions{albumFolder: folder, albumEmbedCover: artRes.EmbedPath, albumArtist: albumArtist, index: idx, total: total, albumDiscTotal: discTotal}
 			if err := m.ripTrack(ctx, p, source, tid, "", opts); err != nil {
 				errCh <- err
 			}
@@ -836,6 +837,15 @@ func (m *Main) trackOutputPath(source, id, title, ext string, trackMeta map[stri
 		base = albumFolder
 		if m.Config.Session.Downloads.DiscSubdirectories && albumDiscTotal > 1 {
 			discNumber := intFromAny(trackMeta["media_number"])
+			if discNumber == 0 {
+				discNumber = intFromAny(trackMeta["volumeNumber"])
+			}
+			if discNumber == 0 {
+				discNumber = intFromAny(trackMeta["disk_number"])
+			}
+			if discNumber == 0 {
+				discNumber = 1
+			}
 			if discNumber > 0 {
 				base = filepath.Join(base, "Disc "+strconv.Itoa(discNumber))
 			}
@@ -1012,6 +1022,9 @@ func buildTagMetadata(trackMeta map[string]any, title, source, trackID string, o
 	if albumArtist == "" {
 		albumArtist = artist
 	}
+	if strings.TrimSpace(opts.albumArtist) != "" {
+		albumArtist = strings.TrimSpace(opts.albumArtist)
+	}
 	trackNumber := intFromAny(trackMeta["track_number"])
 	if trackNumber == 0 {
 		trackNumber = intFromAny(trackMeta["trackNumber"])
@@ -1020,6 +1033,9 @@ func buildTagMetadata(trackMeta map[string]any, title, source, trackID string, o
 	if discNumber == 0 {
 		discNumber = intFromAny(trackMeta["volumeNumber"])
 	}
+	if discNumber == 0 {
+		discNumber = intFromAny(trackMeta["disk_number"])
+	}
 	date := stringFromAny(trackMeta["release_date_original"])
 	if date == "" {
 		date = stringFromAny(trackMeta["release_date"])
@@ -1046,9 +1062,15 @@ func buildTagMetadata(trackMeta map[string]any, title, source, trackID string, o
 	if discTotal == 0 {
 		discTotal = intFromAny(trackMeta["numberOfVolumes"])
 	}
+	if discTotal == 0 && opts.albumDiscTotal > 0 {
+		discTotal = opts.albumDiscTotal
+	}
 	if opts.forPlaylist {
 		discTotal = 1
 	}
+	if !opts.forPlaylist && discNumber == 0 {
+		discNumber = 1
+	}
 
 	genre := nestedString(trackMeta, "genre", "name")
 	if genre == "" {

internal/app/app_test.go

@@ -6,6 +6,7 @@ import (
 	"net/http/httptest"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"streamrip-go/internal/audio/tag"
@@ -368,6 +369,51 @@ func TestResolveAllFailedReturnsError(t *testing.T) {
 	}
 }
 
+func TestBuildTagMetadataUsesAlbumArtistOverride(t *testing.T) {
+	meta := map[string]any{
+		"title":        "One Step Too Far",
+		"track_number": float64(15),
+		"performer":    map[string]any{"name": "Faithless"},
+		"artist":       map[string]any{"name": "Faithless"},
+		"album": map[string]any{
+			"id":     "23324600",
+			"title":  "Greatest Hits (Deluxe)",
+			"artist": map[string]any{"name": "Faithless"},
+		},
+	}
+	tags := buildTagMetadata(meta, "One Step Too Far", "tidal", "23324615", ripTrackOptions{albumArtist: "Dido", albumDiscTotal: 2})
+	if tags.AlbumArtist != "Dido" {
+		t.Fatalf("album artist = %q, want Dido", tags.AlbumArtist)
+	}
+	if tags.DiscNumber != 1 {
+		t.Fatalf("disc number = %d, want 1", tags.DiscNumber)
+	}
+	if tags.DiscTotal != 2 {
+		t.Fatalf("disc total = %d, want 2", tags.DiscTotal)
+	}
+}
+
+func TestTrackOutputPathFallsBackToDisc1(t *testing.T) {
+	tmp := t.TempDir()
+	d := config.DefaultConfigData()
+	d.Downloads.Folder = tmp
+	d.Downloads.DiscSubdirectories = true
+	d.Downloads.SourceSubdirectories = false
+	cfg := &config.Config{File: d, Session: d}
+	m := &Main{Config: cfg}
+
+	meta := map[string]any{
+		"title":        "Song",
+		"track_number": float64(1),
+		"performer":    map[string]any{"name": "Dido"},
+		"album":        map[string]any{"id": "a", "title": "Greatest Hits", "artist": map[string]any{"name": "Dido"}},
+	}
+	path := m.trackOutputPath("tidal", "1", "Song", "flac", meta, filepath.Join(tmp, "Album"), 2)
+	if !strings.Contains(path, string(filepath.Separator)+"Disc 1"+string(filepath.Separator)) {
+		t.Fatalf("expected Disc 1 subdir in path, got %q", path)
+	}
+}
+
 func TestPlaylistRipPipeline(t *testing.T) {
 	tmp := t.TempDir()