fix: SC album defaults to title, filter [Unknown Album] placeholder, fallback file search

- SC resolve: strip yt-dlp placeholder albums (starting with '['), use track title as album for singles
- edit-metadata: if Navidrome path stale, search music root recursively for file by name
- Both single and playlist SC track handling updated

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

backend/novasonic-server.js

@@ -46,6 +46,22 @@ if (!fs.existsSync(CONFIG.musicPath)) {
   fs.mkdirSync(CONFIG.musicPath, { recursive: true });
 }
 
+// Search for a file by exact name anywhere under a directory (max depth 5)
+function _findFileRecursive(dir, name, depth = 0) {
+  if (depth > 5) return null;
+  try {
+    for (const entry of fs.readdirSync(dir, { withFileTypes: true })) {
+      if (entry.isDirectory()) {
+        const found = _findFileRecursive(path.join(dir, entry.name), name, depth + 1);
+        if (found) return found;
+      } else if (entry.name === name) {
+        return path.join(dir, entry.name);
+      }
+    }
+  } catch {}
+  return null;
+}
+
 // ─── QUEUE ────────────────────────────────────────────────────────────────────
 let activeDownloads = 0;
 const downloadQueue = [];
@@ -420,6 +436,7 @@ app.post('/api/soundcloud/resolve', async (req, res) => {
         artworkUrl:  e.thumbnail || '',
         duration:    e.duration  || 0,
         genre:       e.genre    || '',
+        album:       (e.album && !e.album.startsWith('[')) ? e.album : (e.title || ''),
         sourceUrl:   e.url || e.webpage_url || '',
       }));
       res.json({
@@ -430,13 +447,16 @@ app.post('/api/soundcloud/resolve', async (req, res) => {
         tracks,
       });
     } else {
+      // Filter yt-dlp placeholder values — treat them as empty
+      const scAlbum = (data.album && !data.album.startsWith('[')) ? data.album : '';
       const track = {
         trackName:  data.title    || '',
         artistName: data.uploader || data.artist || '',
         artworkUrl: data.thumbnail || '',
         duration:   data.duration  || 0,
         genre:      data.genre    || '',
-        album:      data.album    || '',
+        // Use track title as album for singles with no real album
+        album:      scAlbum || data.title || '',
         year:       data.upload_date ? parseInt(data.upload_date.slice(0, 4), 10) : undefined,
         sourceUrl:  url,
       };
@@ -516,7 +536,14 @@ app.post('/api/edit-metadata', async (req, res) => {
 
   // If not absolute, try relative to music root
   if (!path.isAbsolute(filePath)) filePath = path.join(CONFIG.musicPath, filePath);
-  if (!fs.existsSync(filePath)) return res.status(404).json({ error: `File not found: ${filePath}` });
+
+  // Fallback: if Navidrome path stale/wrong, search for the file by name under music root
+  if (!fs.existsSync(filePath)) {
+    const fileName = path.basename(filePath);
+    const found = _findFileRecursive(CONFIG.musicPath, fileName);
+    if (found) { filePath = found; }
+    else return res.status(404).json({ error: `File not found: ${filePath}` });
+  }
 
   // Resolve artwork: base64 > URL
   let artFile = null;