fix: add YTM 'Songs only' filter param to search URL

Without &params=EgWKAQII..., yt-dlp gets a mixed feed of videos,
channels and playlists alongside tracks — same query that shows the
correct song first in the browser "Titel" tab returned nursery rhyme
videos and unrelated channels. This param is YTM's internal 'Songs'
filter (equivalent to clicking the Titel tab).

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

backend/novasonic-server.js

@@ -83,7 +83,9 @@ function buildTitleKeywords(title) {
     .filter(w => w.length >= 3 && !VARIANT_WORDS.has(w.toLowerCase()) && !STOPWORDS.has(w.toLowerCase()));
   const main = words.sort((a, b) => b.length - a.length)[0] || '';
   const qualifier = lower.includes('mix') ? MIX_QUALIFIERS.find(q => lower.includes(q)) : null;
-  const result = main ? [main] : [];
+  // Make trailing 's' optional so "Whispers?" matches both "Whisper" and "Whispers" in yt-dlp regex
+  const toPattern = w => (w.length >= 4 && w.endsWith('s')) ? w + '?' : w;
+  const result = main ? [toPattern(main)] : [];
   if (qualifier && main.toLowerCase() !== qualifier) result.push(qualifier);
   return result;
 }
@@ -272,7 +274,10 @@ async function downloadTrack({ jobId, artist, albumArtist, title, album, year, t
     );
   });
 
-  const ytmUrl = `https://music.youtube.com/search?q=${encodeURIComponent(query)}`;
+  // &params= is YTM's "Songs only" filter (same as clicking "Titel" tab in the browser).
+  // Without it yt-dlp gets a mixed feed of videos, channels, and playlists as well.
+  const YTM_SONGS_PARAM = 'EgWKAQIIAWoKEAkQBRAKEAMQBA%3D%3D';
+  const ytmUrl = `https://music.youtube.com/search?q=${encodeURIComponent(query)}&params=${YTM_SONGS_PARAM}`;
   // Snapshot files already in dir before we start — so hasAudio() only detects NEW files
   // from the current download attempt, not pre-existing files from parallel jobs.
   let snapBefore = new Set(fs.readdirSync(dir));

src/ui.js

@@ -371,7 +371,9 @@ async function _createNdPlaylist(tracks, name) {
     toast('🎵 Erstelle Navidrome-Playlist…');
     const songIds = [];
     const missing = [];
-    const norm = s => s?.toLowerCase().trim() || '';
+    // Normalize: lowercase, trim, strip diacritics (ø→o, ä→a, etc.) for fuzzy matching
+    const norm  = s => s?.toLowerCase().trim() || '';
+    const normD = s => norm(s).normalize('NFD').replace(/[̀-ͯ]/g, '').replace(/[^\w\s]/g, '');
     for (const t of tracks) {
       if (!t.trackName) continue;
       const missingLabel = t.artistName ? `${t.artistName} – ${t.trackName}` : t.trackName;
@@ -380,13 +382,21 @@ async function _createNdPlaylist(tracks, name) {
         const firstArtist = t.artistName ? t.artistName.split(/[,/•]/)[0].trim() : '';
         const artistQuery = firstArtist ? `${firstArtist} ${t.trackName}` : t.trackName;
         const r = await api('search3', `&query=${encodeURIComponent(artistQuery)}&songCount=20&albumCount=0&artistCount=0`);
-        const songs = r.searchResult3?.song || [];
-        // Strip trailing punctuation from first word so "Kløn," matches "Kløn"
-        const firstWord = s => norm(s).split(/[\s,/•]+/)[0].replace(/\W+$/, '');
-        const match = songs.find(s =>
-          norm(s.title) === norm(t.trackName) &&
-          firstWord(s.artist) === firstWord(firstArtist || t.artistName)
-        ) || songs.find(s => norm(s.title) === norm(t.trackName));
+        let songs = r.searchResult3?.song || [];
+        // If artist+title query returned no title match (e.g. special chars in artist like "Kløn"),
+        // retry with title-only so the track can still be found
+        if (!songs.some(s => norm(s.title) === norm(t.trackName))) {
+          try {
+            const r2 = await api('search3', `&query=${encodeURIComponent(t.trackName)}&songCount=20&albumCount=0&artistCount=0`);
+            songs = r2.searchResult3?.song || [];
+          } catch { /* keep original songs */ }
+        }
+        // firstWordD: first word of artist, diacritics stripped — "Kløn" and "Klon" both → "klon"
+        const firstWordD = s => normD(s).split(/\s+/)[0];
+        const titleMatch = s => norm(s.title) === norm(t.trackName);
+        const artistMatch = s => firstWordD(s.artist) === firstWordD(firstArtist || t.artistName);
+        const match = songs.find(s => titleMatch(s) && artistMatch(s))
+                   || songs.find(s => titleMatch(s));
         if (match) songIds.push(match.id);
         else missing.push(missingLabel);
       } catch { missing.push(missingLabel); }