feat(discovery): Navidrome AudioMuse-AI client integration and library scoping

Add per-server toggle for AudioMuse-style discovery: Instant Mix via
getSimilarSongs, server similar artists instead of Last.fm on artist pages,
and higher similar-artist count in Now Playing when enabled.

When browsing a single music folder, filter similar/top song results by
album ids from that scope (Navidrome does not apply musicFolderId to those
endpoints). Request larger similar batches under a narrow scope.

Keep radio-from-track as two blocks (shuffled top songs, then shuffled
similar-by-artist) so it differs from Instant Mix. Show Alpha badge beside
the setting. Add research/ to .gitignore.

src/pages/ArtistDetail.tsx

@@ -73,6 +73,9 @@ export default function ArtistDetail() {
   const downloadArtist = useOfflineStore(s => s.downloadArtist);
   const bulkProgress = useOfflineJobStore(s => s.bulkProgress);
   const activeServerId = useAuthStore(s => s.activeServerId) ?? '';
+  const audiomuseNavidromeEnabled = useAuthStore(
+    s => !!(s.activeServerId && s.audiomuseNavidromeByServer[s.activeServerId]),
+  );
   const musicLibraryFilterVersion = useAuthStore(s => s.musicLibraryFilterVersion);
   const entityRatingSupportByServer = useAuthStore(s => s.entityRatingSupportByServer);
   const setEntityRatingSupport = useAuthStore(s => s.setEntityRatingSupport);
@@ -95,12 +98,6 @@ export default function ArtistDetail() {
       // Render the page immediately from local data
       setLoading(false);
 
-      // Fetch artist info (may trigger slow external lookup on the server)
-      // and top songs in the background — do not block rendering
-      getArtistInfo(id).then(artistInfo => {
-        if (!cancelled) setInfo(artistInfo ?? null);
-      }).catch(() => {});
-
       getTopSongs(artistData.artist.name).then(songsData => {
         if (!cancelled) setTopSongs(songsData ?? []);
       }).catch(() => {});
@@ -110,6 +107,15 @@ export default function ArtistDetail() {
     return () => { cancelled = true; };
   }, [id]);
 
+  useEffect(() => {
+    if (!id) return;
+    let cancelled = false;
+    getArtistInfo(id, { similarArtistCount: audiomuseNavidromeEnabled ? 24 : undefined }).then(artistInfo => {
+      if (!cancelled) setInfo(artistInfo ?? null);
+    }).catch(() => {});
+    return () => { cancelled = true; };
+  }, [id, audiomuseNavidromeEnabled]);
+
   useEffect(() => {
     if (!id) return;
     if (artist && artist.id === id) setArtistEntityRating(artist.userRating ?? 0);
@@ -174,7 +180,7 @@ export default function ArtistDetail() {
   }, [artist?.id, musicLibraryFilterVersion]);
 
   useEffect(() => {
-    if (!artist || !lastfmIsConfigured()) return;
+    if (!artist || audiomuseNavidromeEnabled || !lastfmIsConfigured()) return;
     setSimilarArtists([]);
     setSimilarLoading(true);
     lastfmGetSimilarArtists(artist.name).then(async names => {
@@ -197,7 +203,7 @@ export default function ArtistDetail() {
       setSimilarArtists(found);
       setSimilarLoading(false);
     }).catch(() => setSimilarLoading(false));
-  }, [artist?.id, musicLibraryFilterVersion]);
+  }, [artist?.id, musicLibraryFilterVersion, audiomuseNavidromeEnabled]);
 
   const openLink = (url: string, key: string) => {
     open(url);
@@ -331,6 +337,15 @@ export default function ArtistDetail() {
   const coverId = artist.coverArt || artist.id;
   const wikiUrl = `https://en.wikipedia.org/wiki/${encodeURIComponent(artist.name)}`;
 
+  const serverSimilarArtists: SubsonicArtist[] = (info?.similarArtist ?? []).map(sa => ({
+    id: sa.id,
+    name: sa.name,
+    albumCount: sa.albumCount,
+  }));
+  const showAudiomuseSimilar = audiomuseNavidromeEnabled && serverSimilarArtists.length > 0;
+  const showLastfmSimilar = !audiomuseNavidromeEnabled && lastfmIsConfigured() && (similarLoading || similarArtists.length > 0);
+  const showSimilarSection = showAudiomuseSimilar || showLastfmSimilar;
+
   return (
     <div className="content-body animate-fade-in">
       <button
@@ -564,20 +579,19 @@ export default function ArtistDetail() {
          </>
        )}
 
-      {/* Similar Artists (Last.fm) */}
-      {lastfmIsConfigured() && (similarLoading || similarArtists.length > 0) && (
+      {showSimilarSection && (
         <>
           <h2 className="section-title" style={{ marginTop: '2rem', marginBottom: '1rem' }}>
             {t('artistDetail.similarArtists')}
           </h2>
-          {similarLoading ? (
+          {showLastfmSimilar && similarLoading ? (
             <div style={{ display: 'flex', alignItems: 'center', gap: '0.75rem', color: 'var(--text-muted)', fontSize: '0.875rem' }}>
               <div className="spinner" style={{ width: 16, height: 16, borderTopColor: 'currentColor' }} />
               {t('artistDetail.loading')}
             </div>
           ) : (
             <div style={{ display: 'flex', flexWrap: 'wrap', gap: '0.5rem' }}>
-              {similarArtists.map(a => (
+              {(showAudiomuseSimilar ? serverSimilarArtists : similarArtists).map(a => (
                 <button
                   key={a.id}
                   className="artist-ext-link"
@@ -592,7 +606,7 @@ export default function ArtistDetail() {
       )}
 
       {/* Albums */}
-      <h2 className="section-title" style={{ marginTop: (info?.biography || topSongs.length > 0 || lastfmIsConfigured()) ? '2rem' : '0', marginBottom: '1rem' }}>
+      <h2 className="section-title" style={{ marginTop: (info?.biography || topSongs.length > 0 || showSimilarSection || (lastfmIsConfigured() && !audiomuseNavidromeEnabled)) ? '2rem' : '0', marginBottom: '1rem' }}>
         {t('artistDetail.albumsBy', { name: artist.name })}
       </h2>
 

src/pages/NowPlaying.tsx

@@ -3,6 +3,7 @@ import { useNavigate } from 'react-router-dom';
 import { useTranslation } from 'react-i18next';
 import { Music, Star, ExternalLink, MicVocal, Heart } from 'lucide-react';
 import { usePlayerStore } from '../store/playerStore';
+import { useAuthStore } from '../store/authStore';
 import { useLyricsStore } from '../store/lyricsStore';
 import {
   buildCoverArtUrl, coverArtCacheKey, getSong, star, unstar,
@@ -217,6 +218,9 @@ export default function NowPlaying() {
   const activeTab       = useLyricsStore(s => s.activeTab);
   const isQueueVisible  = usePlayerStore(s => s.isQueueVisible);
   const toggleQueue     = usePlayerStore(s => s.toggleQueue);
+  const audiomuseNavidromeEnabled = useAuthStore(
+    s => !!(s.activeServerId && s.audiomuseNavidromeByServer[s.activeServerId]),
+  );
 
   const stableNavigate = useCallback((path: string) => navigate(path), [navigate]);
 
@@ -231,8 +235,10 @@ export default function NowPlaying() {
   const [artistInfo, setArtistInfo] = useState<SubsonicArtistInfo | null>(null);
   useEffect(() => {
     if (!currentTrack?.artistId) { setArtistInfo(null); return; }
-    getArtistInfo(currentTrack.artistId).then(setArtistInfo).catch(() => setArtistInfo(null));
-  }, [currentTrack?.artistId]);
+    getArtistInfo(currentTrack.artistId, { similarArtistCount: audiomuseNavidromeEnabled ? 24 : undefined })
+      .then(setArtistInfo)
+      .catch(() => setArtistInfo(null));
+  }, [currentTrack?.artistId, audiomuseNavidromeEnabled]);
 
   // Album tracks
   const [albumTracks, setAlbumTracks] = useState<SubsonicSong[]>([]);

src/pages/Settings.tsx

@@ -5,7 +5,7 @@ import { useNavigate, useLocation } from 'react-router-dom';
 import {
   Wifi, WifiOff, Globe, Music2, Sliders, LogOut, CheckCircle2, FolderOpen,
   Palette, Server, Plus, Trash2, Eye, EyeOff, Info, ExternalLink, Shuffle, X, Play, Type, Keyboard, ChevronDown,
-  GripVertical, PanelLeft, RotateCcw, LayoutGrid, AppWindow, HardDrive, Upload, Download, Waves, Star, Clock, ZoomIn
+  GripVertical, PanelLeft, RotateCcw, LayoutGrid, AppWindow, HardDrive, Upload, Download, Waves, Star, Clock, ZoomIn, Sparkles
 } from 'lucide-react';
 import { exportBackup, importBackup } from '../utils/backup';
 import { showToast } from '../utils/toast';
@@ -1656,6 +1656,42 @@ export default function Settings() {
                           </button>
                         </div>
                       </div>
+                      <div
+                        className="settings-toggle-row"
+                        style={{ marginTop: '0.75rem', paddingTop: '0.75rem', borderTop: '1px solid color-mix(in srgb, var(--text-muted) 18%, transparent)' }}
+                      >
+                        <div style={{ display: 'flex', alignItems: 'flex-start', gap: '0.5rem', minWidth: 0 }}>
+                          <Sparkles size={16} style={{ color: 'var(--accent)', flexShrink: 0, marginTop: 2 }} />
+                          <div>
+                            <div style={{ fontWeight: 500, display: 'flex', alignItems: 'center', gap: 8, flexWrap: 'wrap' }}>
+                              {t('settings.audiomuseTitle')}
+                              <span
+                                style={{
+                                  fontSize: 10,
+                                  fontWeight: 600,
+                                  textTransform: 'uppercase',
+                                  letterSpacing: '0.04em',
+                                  padding: '2px 6px',
+                                  borderRadius: 4,
+                                  background: 'color-mix(in srgb, var(--color-warning, #f59e0b) 22%, transparent)',
+                                  color: 'var(--text-primary)',
+                                }}
+                              >
+                                {t('settings.hotCacheAlphaBadge')}
+                              </span>
+                            </div>
+                            <div style={{ fontSize: 12, color: 'var(--text-muted)', lineHeight: 1.45 }}>{t('settings.audiomuseDesc')}</div>
+                          </div>
+                        </div>
+                        <label className="toggle-switch" aria-label={t('settings.audiomuseTitle')}>
+                          <input
+                            type="checkbox"
+                            checked={!!auth.audiomuseNavidromeByServer[srv.id]}
+                            onChange={e => auth.setAudiomuseNavidromeEnabled(srv.id, e.target.checked)}
+                          />
+                          <span className="toggle-track" />
+                        </label>
+                      </div>
                     </div>
                   );
                 })}