feat: normalize Japanese artist/title names to romaji at storage time

- Add romajiForStorage() to romaji.js — smart word spacing + Title Case
- ytdlp.js: apply to folder names, filenames, and embedded tags
- novasonic-server.js: apply in edit-metadata endpoint and Spotify resolve
- spotify.js: update track artist/name from iTunes canonical English names

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/lib/romaji.js

@@ -75,6 +75,25 @@ function toRomaji(text) {
   return _hiraToRomaji(hira).toLowerCase();
 }
 
+// Human-readable romaji for storage: spaces between words, Title Case, ASCII preserved as-is.
+function romajiForStorage(text) {
+  if (!text || !_tokenizer || !JP_RE.test(text)) return text || '';
+  const tokens = _tokenizer.tokenize(text);
+  const parts = tokens.map(t => {
+    const r = t.reading;
+    if (!r || r === '*') return t.surface_form; // ASCII — keep original
+    return _hiraToRomaji(_kataToHira(r));        // Japanese — convert (lowercase)
+  });
+  // Add space between adjacent alphabetic segments (word separation for names/titles)
+  const joined = parts.reduce((acc, part, i) => {
+    if (i === 0) return part;
+    const needsSpace = /[a-zA-Z0-9]$/.test(parts[i - 1]) && /^[a-zA-Z]/.test(part);
+    return acc + (needsSpace ? ' ' : '') + part;
+  }, '');
+  // Title-case: capitalize first lowercase letter of each word, preserve existing uppercase
+  return joined.replace(/\b([a-z])/g, c => c.toUpperCase()).replace(/\s+/g, ' ').trim();
+}
+
 // ─── INDEX BUILDER ────────────────────────────────────────────────────────────
 
 const romajiCache = new Map();
@@ -123,4 +142,4 @@ function clearRomajiCache() { romajiCache.clear(); }
 
 function isTokenizerReady() { return !!_tokenizer; }
 
-module.exports = { buildRomajiIndex, clearRomajiCache, isTokenizerReady, fetchNdSongs: _fetchNdSongs };
+module.exports = { buildRomajiIndex, clearRomajiCache, isTokenizerReady, fetchNdSongs: _fetchNdSongs, romajiForStorage };

backend/lib/ytdlp.js

@@ -7,6 +7,7 @@ const {
   sanitize, navidromeArtist,
   downloadArtwork, findExistingTrack,
 } = require('./metadata');
+const { romajiForStorage } = require('./romaji');
 
 function buildTitleKeywords(title) {
   const VARIANT_WORDS = new Set(['sped','speedup','slowed','reverb','nightcore','karaoke','parody','remix','cover','acoustic','instrumental']);
@@ -49,16 +50,19 @@ function buildVariantFilter(title) {
 
 async function downloadTrack({ jobId, artist, albumArtist, title, album, year, trackNum, totalTracks, discNum, discTotal, compilation, genre, artworkUrl, explicit, outputDir, durationMs, sourceUrl }) {
   const mainArtist = albumArtist || artist;
-  const safeArtist = sanitize(mainArtist.split(/[,;&]/)[0].trim());
+  const mainArtistRomaji = romajiForStorage(mainArtist) || mainArtist;
+  const artistRomaji     = romajiForStorage(artist)     || artist;
+  const titleRomaji      = romajiForStorage(title)      || title;
+  const safeArtist = sanitize(mainArtistRomaji.split(/[,;&]/)[0].trim());
   const safeAlbum  = sanitize(album || 'Singles');
   const dir = path.join(outputDir || CONFIG.musicPath, safeArtist, safeAlbum);
   fs.mkdirSync(dir, { recursive: true });
 
-  const safeTitle        = sanitize(title);
+  const safeTitle        = sanitize(titleRomaji);
   const trackPrefix      = trackNum ? String(trackNum).padStart(2, '0') + ' - ' : '';
   // Filename format: "{01 - }Artist1, Artist2 - Title.ext"
   // Use track artist (not albumArtist) so all credited artists appear in the filename
-  const safeArtistForFile = sanitize(artist.replace(/;/g, ','));
+  const safeArtistForFile = sanitize(artistRomaji.replace(/;/g, ','));
   const fileBase          = `${trackPrefix}${safeArtistForFile} - ${safeTitle}`;
 
   const existing = findExistingTrack(dir, trackPrefix, safeTitle, safeArtistForFile);
@@ -299,13 +303,16 @@ async function embedMetadata({ jobId, audioFile, dir, trackPrefix, safeTitle, ar
     if (hasCover) ffArgs.push('-i', coverPath);
     ffArgs.push('-map', '0:a');
     if (hasCover) ffArgs.push('-map', '1:v');
+    const storedTitle       = romajiForStorage(title)                                       || title;
+    const storedArtist      = romajiForStorage(navidromeArtist(artist))                    || navidromeArtist(artist);
+    const storedAlbumArtist = romajiForStorage(mainArtist.replace(/\s+&\s+/g, ', '))       || mainArtist.replace(/\s+&\s+/g, ', ');
     ffArgs.push(
       '-c',             'copy',
       '-map_metadata',  '-1',
       '-id3v2_version', '3',
-      '-metadata', `title=${title}`,
+      '-metadata', `title=${storedTitle}`,
-      '-metadata', `artist=${navidromeArtist(artist)}`,
+      '-metadata', `artist=${storedArtist}`,
-      '-metadata', `album_artist=${mainArtist.replace(/\s+&\s+/g, ', ')}`,
+      '-metadata', `album_artist=${storedAlbumArtist}`,
     );
     if (album)       ffArgs.push('-metadata', `album=${album}`);
     if (year)        ffArgs.push('-metadata', `date=${String(year)}`);

backend/novasonic-server.js

@@ -19,7 +19,7 @@ const CONFIG    = require('./lib/config');
 const { jobs, updateJob, log } = require('./lib/jobs');
 const { sanitize, lookupItunesTrackMeta, fetchItunesTracks, searchItunesAlbumTracks } = require('./lib/metadata');
 const { downloadTrack, downloadAlbumTracks } = require('./lib/downloader');
-const { buildRomajiIndex, clearRomajiCache, isTokenizerReady, fetchNdSongs } = require('./lib/romaji');
+const { buildRomajiIndex, clearRomajiCache, isTokenizerReady, fetchNdSongs, romajiForStorage } = require('./lib/romaji');
 
 // ─── INIT ─────────────────────────────────────────────────────────────────────
 const app = express();
@@ -225,6 +225,13 @@ app.post('/api/spotify/resolve', async (req, res) => {
       setTimeout(() => reject(new Error('Zeitüberschreitung — Spotify API antwortet nicht (>120s)')), 120000)
     );
     const data = await Promise.race([_resolveSpotifyViaSpotdl(url), timeout]);
+    // Normalize Japanese artist/title names to romaji before sending to frontend
+    if (data.tracks) {
+      for (const t of data.tracks) {
+        if (t.artistName) t.artistName = romajiForStorage(t.artistName) || t.artistName;
+        if (t.trackName)  t.trackName  = romajiForStorage(t.trackName)  || t.trackName;
+      }
+    }
     res.json(data);
   } catch(e) {
     console.error('[spotify/resolve]', e.message);
@@ -609,6 +616,11 @@ app.post('/api/edit-metadata', async (req, res) => {
   const normalArtist      = _normalizeArtists(artist, ';');
   const normalAlbumArtist = _normalizeArtists(albumArtist, ', ');
 
+  // Convert Japanese names to romaji for storage
+  const romajiArtist      = normalArtist      ? romajiForStorage(normalArtist)      || normalArtist      : normalArtist;
+  const romajiAlbumArtist = normalAlbumArtist ? romajiForStorage(normalAlbumArtist) || normalAlbumArtist : normalAlbumArtist;
+  const romajiTitle       = title             ? romajiForStorage(title)             || title             : title;
+
   // Resolve file path from Navidrome
   let filePath;
   let ndSong;
@@ -673,9 +685,9 @@ app.post('/api/edit-metadata', async (req, res) => {
         ffArgs.push('-map', '0:v?'); // '?' = optional, no error if file has no cover
       }
       ffArgs.push('-c', 'copy', '-map_metadata', '-1', '-id3v2_version', '3');
-      if (title)            ffArgs.push('-metadata', `title=${title}`);
+      if (romajiTitle)       ffArgs.push('-metadata', `title=${romajiTitle}`);
-      if (normalArtist)     ffArgs.push('-metadata', `artist=${normalArtist}`);
+      if (romajiArtist)      ffArgs.push('-metadata', `artist=${romajiArtist}`);
-      const resolvedAlbumArtist = normalAlbumArtist || (normalArtist ? normalArtist.split(';')[0].trim() : null);
+      const resolvedAlbumArtist = romajiAlbumArtist || (romajiArtist ? romajiArtist.split(';')[0].trim() : null);
       if (resolvedAlbumArtist)   ffArgs.push('-metadata', `album_artist=${resolvedAlbumArtist}`);
       if (album)       ffArgs.push('-metadata', `album=${album}`);
       if (year)        ffArgs.push('-metadata', `date=${year}`);
@@ -704,8 +716,8 @@ app.post('/api/edit-metadata', async (req, res) => {
 
     // 1. Rename file if title changed — convention: {01 - }?{Artist} - {Title}.ext
     if (title) {
-      const safeTitle      = sanitize(title);
+      const safeTitle      = sanitize(romajiTitle || title);
-      const fileArtist     = (normalArtist || ndSong?.artist || '').replace(/;/g, ',');
+      const fileArtist     = (romajiArtist || ndSong?.artist || '').replace(/;/g, ',');
       const safeArtistPart = fileArtist ? sanitize(fileArtist) + ' - ' : '';
       const prefix         = trackNum ? String(trackNum).padStart(2, '0') + ' - ' : '';
       const newName        = `${prefix}${safeArtistPart}${safeTitle}${fileExt}`;
@@ -720,7 +732,7 @@ app.post('/api/edit-metadata', async (req, res) => {
     const oldAlbumDir  = path.dirname(currentFile);
     const oldArtistDir = path.dirname(oldAlbumDir);
     const newAlbumName  = album             ? sanitize(album) : path.basename(oldAlbumDir);
-    const newArtistName = normalAlbumArtist ? sanitize(normalAlbumArtist.split(/[,;&]/)[0].trim()) : path.basename(oldArtistDir);
+    const newArtistName = romajiAlbumArtist ? sanitize(romajiAlbumArtist.split(/[,;&]/)[0].trim()) : path.basename(oldArtistDir);
     const newDir = path.join(CONFIG.musicPath, newArtistName, newAlbumName);
 
     if (newDir !== oldAlbumDir) {

src/spotify.js

@@ -295,6 +295,10 @@ async function _loadSpotifyTrackArtwork(tracks, listEl) {
         if (match.trackExplicitness)  t.trackExplicitness  = match.trackExplicitness;
         if (match.previewUrl)         t.previewUrl         = match.previewUrl;
         if (match.trackTimeMillis)    t.durationMs         = match.trackTimeMillis;
+        // Use iTunes canonical English/romaji names — more accurate than Spotify (which may use Japanese)
+        if (match.artistName)         t.artistName         = match.artistName;
+        const JP_RE = /[぀-ヿ一-鿿]/;
+        if (JP_RE.test(t.trackName) && match.trackName) t.trackName = match.trackName;
         if (window._spotifyResolved?.tracks?.[idx]) Object.assign(window._spotifyResolved.tracks[idx], t);
         const url = match.artworkUrl100 || match.artworkUrl60 || '';
         if (url) _setArt(artEls[idx], url);