prefer release with no disambiguation, match track counts

discover.go

@@ -22,7 +22,8 @@ type mbArtistCredit struct {
 }
 
 type mbMedia struct {
-	Format string `json:"format"`
+	Format     string `json:"format"`
+	TrackCount int    `json:"track-count"`
 }
 
 type mbRelease struct {
@@ -55,6 +56,22 @@ type mbReleaseGroup struct {
 	FirstReleaseDate string `json:"first-release-date"`
 }
 
+// releaseTrackCount returns the total number of tracks across all media in a release.
+func releaseTrackCount(r mbRelease) int {
+	total := 0
+	for _, m := range r.Media {
+		total += m.TrackCount
+	}
+	return total
+}
+
+// getMBRelease fetches a single release by MBID (with media/track-count included).
+func getMBRelease(mbid string) (*mbRelease, error) {
+	var r mbRelease
+	err := mbGet(fmt.Sprintf("/ws/2/release/%s?fmt=json&inc=media", url.QueryEscape(mbid)), &r)
+	return &r, err
+}
+
 func mbGet(path string, out interface{}) error {
 	req, err := http.NewRequest("GET", "https://musicbrainz.org"+path, nil)
 	if err != nil {
@@ -131,8 +148,8 @@ func timeStringIsBefore(ts1, ts2 string) (bool, error) {
 }
 
 // pickBestRelease selects the preferred release from a list.
-// Format (CD > Digital Media > *) is the primary sort key;
+// No disambiguation (canonical release) is the primary sort key;
-// country (KR > JP > XW > *) breaks ties.
+// format (CD > Digital Media > *) is secondary; country (KR > XW > *) breaks ties.
 func pickBestRelease(releases []mbRelease) *mbRelease {
 	if len(releases) == 0 {
 		return nil
@@ -140,6 +157,20 @@ func pickBestRelease(releases []mbRelease) *mbRelease {
 	best := &releases[0]
 	for i := 1; i < len(releases); i++ {
 		r := &releases[i]
+
+		rNoDisamb := r.Disambiguation == ""
+		bestNoDisamb := best.Disambiguation == ""
+
+		// Prefer releases with no disambiguation — they are the canonical default.
+		if rNoDisamb && !bestNoDisamb {
+			best = r
+			continue
+		}
+		if !rNoDisamb && bestNoDisamb {
+			continue
+		}
+
+		// Both have the same disambiguation status; use date/format/country.
 		if before, err := timeStringIsBefore(r.Date, best.Date); before && err == nil {
 			rf, bf := releaseFormatScore(*r), releaseFormatScore(*best)
 			if rf > bf || (rf == bf && releaseCountryScore(*r) > releaseCountryScore(*best)) {
@@ -225,18 +256,20 @@ func fetchArtist(artistMBID, artistName string, logf func(string)) error {
 		time.Sleep(time.Second) // MusicBrainz rate limit
 		rel := pickBestReleaseForGroup(rg.ID)
 		releaseMBID := ""
+		trackCount := 0
 		if rel == nil {
 			logf(fmt.Sprintf("  ↳ warning: could not resolve release for group %s, beets will search by name", rg.ID))
 		} else {
 			releaseMBID = rel.ID
+			trackCount = releaseTrackCount(*rel)
 			format := ""
 			if len(rel.Media) > 0 {
 				format = rel.Media[0].Format
 			}
-			logf(fmt.Sprintf("  ↳ selected release: %s [%s / %s]", releaseMBID, format, rel.Country))
+			logf(fmt.Sprintf("  ↳ selected release: %s [%s / %s / %d tracks]", releaseMBID, format, rel.Country, trackCount))
 		}
 
-		folder, err := fetchRelease(artistName, rg.Title, releaseMBID, logf)
+		folder, err := fetchRelease(artistName, rg.Title, releaseMBID, trackCount, logf)
 		if err != nil {
 			log.Printf("[discover] fetch failed for %q by %s: %v", rg.Title, artistName, err)
 			logf(fmt.Sprintf("  ↳ failed: %v", err))
@@ -244,7 +277,7 @@ func fetchArtist(artistMBID, artistName string, logf func(string)) error {
 			continue
 		}
 		// Key the pending download by release group ID for dedup; beets uses releaseMBID.
-		registerDownload(rg.ID, releaseMBID, artistName, rg.Title, folder, nil)
+		registerDownload(rg.ID, releaseMBID, artistName, rg.Title, trackCount, folder, nil)
 		logf(fmt.Sprintf("  ↳ registered for import (release mbid: %s)", releaseMBID))
 	}
 
@@ -383,15 +416,26 @@ func handleDiscoverFetch(w http.ResponseWriter, r *http.Request) {
 
 	log.Printf("[discover] starting fetch: %q by %s (mbid: %s)", body.Album, body.Artist, body.ID)
 	entry := newFetchEntry(body.ID, body.Artist, body.Album)
+
+	// Look up the expected track count from MusicBrainz so the folder-selection
+	// logic can prefer results that match the release we intend to import.
+	trackCount := 0
+	if rel, err := getMBRelease(body.ID); err == nil {
+		trackCount = releaseTrackCount(*rel)
+		log.Printf("[discover] release %s has %d tracks", body.ID, trackCount)
+	} else {
+		log.Printf("[discover] could not fetch release track count for %s: %v", body.ID, err)
+	}
+
 	go func() {
-		folder, err := fetchRelease(body.Artist, body.Album, body.ID, entry.appendLog)
+		folder, err := fetchRelease(body.Artist, body.Album, body.ID, trackCount, entry.appendLog)
 		if err != nil {
 			log.Printf("[discover] fetch failed for %q by %s: %v", body.Album, body.Artist, err)
 			entry.finish(err)
 			return
 		}
 		log.Printf("[discover] fetch complete for %q by %s, registering for import", body.Album, body.Artist)
-		registerDownload(body.ID, body.ID, body.Artist, body.Album, folder, entry)
+		registerDownload(body.ID, body.ID, body.Artist, body.Album, trackCount, folder, entry)
 		// entry.finish is called by the monitor when import completes
 	}()
 

monitor.go

@@ -13,14 +13,15 @@ import (
 // pendingDownload tracks a queued slskd download that should be auto-imported
 // once all files have transferred successfully.
 type pendingDownload struct {
-	ID       string      // dedup key (release MBID for single fetches; release group MBID for artist fetches)
+	ID        string      // dedup key (release MBID for single fetches; release group MBID for artist fetches)
-	BeetsMBID string     // release MBID passed to beets --search-id (may differ from ID)
+	BeetsMBID string      // release MBID passed to beets --search-id (may differ from ID)
-	Artist   string
+	Artist    string
-	Album    string
+	Album     string
-	Username string      // slskd peer username
+	Username  string      // slskd peer username
-	Dir      string      // remote directory path on the peer
+	Dir       string      // remote directory path on the peer
-	Files    []slskdFile // files that were queued for download
+	Files     []slskdFile // files that were queued for download
-	Entry    *fetchEntry // fetch card to update with import progress
+	Entry     *fetchEntry // fetch card to update with import progress
+	TrackCount int        // expected number of audio tracks (0 = unknown, skip check)
 }
 
 var (
@@ -31,18 +32,21 @@ var (
 // registerDownload records a queued slskd download for monitoring and eventual
 // auto-import. id is used as the dedup key; beetsMBID is the release MBID
 // forwarded to beets --search-id (may be empty or differ from id).
+// trackCount is the expected number of audio tracks from MusicBrainz; 0 means
+// unknown and the sanity check will be skipped at import time.
 // If entry is nil a new fetchEntry is created so the frontend can discover it
 // via /discover/fetch/list.
-func registerDownload(id, beetsMBID, artist, album string, folder *albumFolder, entry *fetchEntry) {
+func registerDownload(id, beetsMBID, artist, album string, trackCount int, folder *albumFolder, entry *fetchEntry) {
 	pd := &pendingDownload{
-		ID:        id,
+		ID:         id,
-		BeetsMBID: beetsMBID,
+		BeetsMBID:  beetsMBID,
-		Artist:    artist,
+		Artist:     artist,
-		Album:     album,
+		Album:      album,
-		Username:  folder.Username,
+		Username:   folder.Username,
-		Dir:       folder.Dir,
+		Dir:        folder.Dir,
-		Files:     folder.Files,
+		Files:      folder.Files,
-		Entry:     entry,
+		Entry:      entry,
+		TrackCount: trackCount,
 	}
 
 	if entry == nil {
@@ -56,8 +60,8 @@ func registerDownload(id, beetsMBID, artist, album string, folder *albumFolder,
 	pendingDownloads[id] = pd
 	pendingMu.Unlock()
 
-	log.Printf("[monitor] registered: %q by %s (id: %s, beets mbid: %s, peer: %s, %d files)",
+	log.Printf("[monitor] registered: %q by %s (id: %s, beets mbid: %s, peer: %s, %d files, expected tracks: %d)",
-		album, artist, id, beetsMBID, folder.Username, len(folder.Files))
+		album, artist, id, beetsMBID, folder.Username, len(folder.Files), trackCount)
 }
 
 // startMonitor launches a background goroutine that periodically checks whether
@@ -215,6 +219,14 @@ func importPendingRelease(pd *pendingDownload, localDir string) {
 	}
 	logf(fmt.Sprintf("Found %d tracks", len(tracks)))
 
+	if pd.TrackCount > 0 && len(tracks) != pd.TrackCount {
+		entry.finish(fmt.Errorf(
+			"track count mismatch: downloaded %d tracks but release expects %d — aborting to avoid importing wrong edition",
+			len(tracks), pd.TrackCount,
+		))
+		return
+	}
+
 	if err := cleanAlbumTags(localDir); err != nil {
 		logf(fmt.Sprintf("Clean tags warning: %v", err))
 	}

slskd.go

@@ -384,9 +384,12 @@ func getSlskdTransfers(username string) ([]slskdTransferDir, error) {
 // fetchRelease searches slskd for an album, queues the best-quality match for
 // download, and returns the chosen folder so the caller can monitor completion.
 // mbid, if non-empty, will be stored for use during import (beets --search-id).
-func fetchRelease(artist, album, mbid string, logf func(string)) (*albumFolder, error) {
+// trackCount, if > 0, filters candidate folders to those whose audio file count
+// matches the expected number of tracks on the release, so alternate editions
+// with different track counts are not accidentally selected.
+func fetchRelease(artist, album, mbid string, trackCount int, logf func(string)) (*albumFolder, error) {
 	query := artist + " " + album
-	log.Printf("[discover] fetch started: %q by %s", album, artist)
+	log.Printf("[discover] fetch started: %q by %s (expected tracks: %d)", album, artist, trackCount)
 	logf("Starting fetch for: " + query)
 
 	logf("Creating slskd search…")
@@ -418,7 +421,29 @@ func fetchRelease(artist, album, mbid string, logf func(string)) (*albumFolder,
 		return nil, fmt.Errorf("no audio files found for %q by %s", album, artist)
 	}
 
-	best := bestAlbumFolder(folders)
+	// When we know the expected track count, prefer folders that match exactly
+	// so we don't accidentally grab a bonus-track edition or a different version
+	// that won't align with the release MBID we pass to beets.
+	candidates := folders
+	if trackCount > 0 {
+		var matched []albumFolder
+		for _, f := range folders {
+			if len(f.Files) == trackCount {
+				matched = append(matched, f)
+			}
+		}
+		if len(matched) > 0 {
+			log.Printf("[discover] %d/%d folders match expected track count (%d)", len(matched), len(folders), trackCount)
+			logf(fmt.Sprintf("Filtered to %d/%d folders matching expected track count (%d)",
+				len(matched), len(folders), trackCount))
+			candidates = matched
+		} else {
+			log.Printf("[discover] no folders matched expected track count (%d); using best available", trackCount)
+			logf(fmt.Sprintf("Warning: no folders matched expected track count (%d); using best available", trackCount))
+		}
+	}
+
+	best := bestAlbumFolder(candidates)
 	log.Printf("[discover] selected folder: %s from %s (%s, %d files)",
 		best.Dir, best.Username, qualityLabel(best.Quality), len(best.Files))
 	logf(fmt.Sprintf("Selected folder: %s", best.Dir))