feat: synced scrolling lyrics + playlist offline download

- Fetch timed LRC lyrics from LRCLIB API (Navidrome fallback for plain text)
- Synced lyrics component with auto-scroll, active line highlighting, and tap-to-seek
- Past lines fade out, current line enlarges — Spotify-style karaoke experience
- Add "Download All" button on expanded playlists for bulk offline download
- Button shows green checkmark when all songs already downloaded

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

app/api/music/lyrics/route.ts

@@ -9,22 +9,62 @@ interface LyricsResult {
   }
 }
 
+interface LrcLibResult {
+  syncedLyrics?: string | null
+  plainLyrics?: string | null
+}
+
 export async function GET(request: Request) {
   const { searchParams } = new URL(request.url)
   const artist = searchParams.get('artist') || ''
   const title = searchParams.get('title') || ''
 
   if (!artist || !title) {
-    return NextResponse.json({ lyrics: null })
+    return NextResponse.json({ lyrics: null, synced: null })
   }
 
+  // Try LRCLIB first for synced (timed) lyrics
+  try {
+    const controller = new AbortController()
+    const timeout = setTimeout(() => controller.abort(), 4000)
+
+    const lrcRes = await fetch(
+      `https://lrclib.net/api/get?artist_name=${encodeURIComponent(artist)}&track_name=${encodeURIComponent(title)}`,
+      {
+        headers: {
+          'User-Agent': 'SoulSync/1.0 (jeffemmett@gmail.com)',
+        },
+        signal: controller.signal,
+        cache: 'no-store',
+      }
+    )
+    clearTimeout(timeout)
+
+    if (lrcRes.ok) {
+      const lrc: LrcLibResult = await lrcRes.json()
+      if (lrc.syncedLyrics) {
+        return NextResponse.json({
+          lyrics: lrc.plainLyrics || lrc.syncedLyrics.replace(/\[\d{2}:\d{2}\.\d{2,3}\]\s?/g, ''),
+          synced: lrc.syncedLyrics,
+        })
+      }
+      if (lrc.plainLyrics) {
+        return NextResponse.json({ lyrics: lrc.plainLyrics, synced: null })
+      }
+    }
+  } catch {
+    // LRCLIB unavailable, fall through to Navidrome
+  }
+
+  // Fallback to Navidrome plain lyrics
   try {
     const data = await navidromeGet<LyricsResult>('getLyrics.view', { artist, title })
     return NextResponse.json({
       lyrics: data.lyrics?.value || null,
+      synced: null,
     })
   } catch (error) {
     console.error('Lyrics error:', error)
-    return NextResponse.json({ lyrics: null })
+    return NextResponse.json({ lyrics: null, synced: null })
   }
 }

app/music/page.tsx

@@ -7,7 +7,8 @@ import { JefflixLogo } from '@/components/jefflix-logo'
 import { SongRow } from '@/components/music/search-results'
 import { useMusicPlayer, type Track } from '@/components/music/music-provider'
 import { MusicBrainzResultsSection } from '@/components/music/musicbrainz-results'
-import { Search, Music, Download, Loader2, ArrowLeft, AlertCircle, ListMusic, ChevronRight, ChevronDown, WifiOff, Users } from 'lucide-react'
+import { useOffline } from '@/lib/stores/offline'
+import { Search, Music, Download, Loader2, ArrowLeft, AlertCircle, ListMusic, ChevronRight, ChevronDown, WifiOff, Users, DownloadCloud, CheckCircle } from 'lucide-react'
 import Link from 'next/link'
 
 interface Playlist {
@@ -33,6 +34,7 @@ interface SlskdFile {
 
 export default function MusicPage() {
   const { state } = useMusicPlayer()
+  const { offlineIds, download: downloadTrack } = useOffline()
   const [query, setQuery] = useState('')
   const [debouncedQuery, setDebouncedQuery] = useState('')
   const [songs, setSongs] = useState<Track[]>([])
@@ -376,36 +378,67 @@ export default function MusicPage() {
                 </p>
               ) : (
                 <div className="border border-border rounded-lg divide-y divide-border overflow-hidden">
-                  {playlists.map((p) => (
+                  {playlists.map((p) => {
+                    // Check how many songs in this playlist are already offline
+                    const allOffline = expandedPlaylist === p.id && playlistSongs.length > 0 &&
+                      playlistSongs.every((s) => offlineIds.has(s.id))
+
+                    return (
                     <div key={p.id}>
-                      <button
-                        onClick={() => togglePlaylist(p.id)}
-                        className="w-full flex items-center gap-3 px-4 py-3 hover:bg-muted/50 transition-colors text-left"
-                      >
-                        <div className="flex-shrink-0 w-12 h-12 rounded overflow-hidden bg-muted">
-                          {p.coverArt ? (
-                            <img
-                              src={`/api/music/cover/${p.coverArt}?size=96`}
-                              alt={p.name}
-                              className="w-full h-full object-cover"
-                              loading="lazy"
-                            />
+                      <div className="flex items-center hover:bg-muted/50 transition-colors">
+                        <button
+                          onClick={() => togglePlaylist(p.id)}
+                          className="flex-1 flex items-center gap-3 px-4 py-3 text-left"
+                        >
+                          <div className="flex-shrink-0 w-12 h-12 rounded overflow-hidden bg-muted">
+                            {p.coverArt ? (
+                              <img
+                                src={`/api/music/cover/${p.coverArt}?size=96`}
+                                alt={p.name}
+                                className="w-full h-full object-cover"
+                                loading="lazy"
+                              />
+                            ) : (
+                              <div className="w-full h-full flex items-center justify-center">
+                                <ListMusic className="h-5 w-5 text-muted-foreground" />
+                              </div>
+                            )}
+                          </div>
+                          <div className="flex-1 min-w-0">
+                            <div className="font-medium text-sm truncate">{p.name}</div>
+                            <div className="text-xs text-muted-foreground">{p.songCount} songs</div>
+                          </div>
+                          {expandedPlaylist === p.id ? (
+                            <ChevronDown className="h-4 w-4 text-muted-foreground flex-shrink-0" />
                           ) : (
-                            <div className="w-full h-full flex items-center justify-center">
-                              <ListMusic className="h-5 w-5 text-muted-foreground" />
-                            </div>
+                            <ChevronRight className="h-4 w-4 text-muted-foreground flex-shrink-0" />
                           )}
-                        </div>
-                        <div className="flex-1 min-w-0">
-                          <div className="font-medium text-sm truncate">{p.name}</div>
-                          <div className="text-xs text-muted-foreground">{p.songCount} songs</div>
-                        </div>
-                        {expandedPlaylist === p.id ? (
-                          <ChevronDown className="h-4 w-4 text-muted-foreground flex-shrink-0" />
-                        ) : (
-                          <ChevronRight className="h-4 w-4 text-muted-foreground flex-shrink-0" />
+                        </button>
+                        {/* Download entire playlist */}
+                        {expandedPlaylist === p.id && playlistSongs.length > 0 && (
+                          <button
+                            onClick={(e) => {
+                              e.stopPropagation()
+                              playlistSongs.forEach((s) => {
+                                if (!offlineIds.has(s.id)) downloadTrack(s)
+                              })
+                            }}
+                            className={`p-2 mr-2 rounded-full transition-colors flex-shrink-0 ${
+                              allOffline
+                                ? 'text-green-500'
+                                : 'text-muted-foreground hover:text-foreground hover:bg-muted/50'
+                            }`}
+                            title={allOffline ? 'All songs downloaded' : 'Download all for offline'}
+                            disabled={allOffline}
+                          >
+                            {allOffline ? (
+                              <CheckCircle className="h-5 w-5" />
+                            ) : (
+                              <DownloadCloud className="h-5 w-5" />
+                            )}
+                          </button>
                         )}
-                      </button>
+                      </div>
 
                       {expandedPlaylist === p.id && (
                         <div className="bg-muted/30 border-t border-border">
@@ -427,7 +460,7 @@ export default function MusicPage() {
                         </div>
                       )}
                     </div>
-                  ))}
+                  )})}
                 </div>
               )}
             </div>

components/music/full-screen-player.tsx

@@ -5,6 +5,7 @@ import { Drawer } from 'vaul'
 import { useMusicPlayer } from './music-provider'
 import { DownloadButton } from './download-button'
 import { PlaylistPicker } from './playlist-picker'
+import { SyncedLyrics } from './synced-lyrics'
 import { Slider } from '@/components/ui/slider'
 import { Button } from '@/components/ui/button'
 import {
@@ -30,6 +31,7 @@ function formatTime(secs: number) {
 export function FullScreenPlayer() {
   const { state, togglePlay, seek, setVolume, nextTrack, prevTrack, setFullScreen, outputDevices, currentOutputId, setOutputDevice } = useMusicPlayer()
   const [lyrics, setLyrics] = useState<string | null>(null)
+  const [syncedLyrics, setSyncedLyrics] = useState<string | null>(null)
   const [loadingLyrics, setLoadingLyrics] = useState(false)
   const [playlistOpen, setPlaylistOpen] = useState(false)
 
@@ -39,11 +41,15 @@ export function FullScreenPlayer() {
   useEffect(() => {
     if (!track) return
     setLyrics(null)
+    setSyncedLyrics(null)
     setLoadingLyrics(true)
     fetch(`/api/music/lyrics?artist=${encodeURIComponent(track.artist)}&title=${encodeURIComponent(track.title)}`)
       .then((r) => r.json())
-      .then((d) => setLyrics(d.lyrics))
-      .catch(() => setLyrics(null))
+      .then((d) => {
+        setLyrics(d.lyrics)
+        setSyncedLyrics(d.synced || null)
+      })
+      .catch(() => { setLyrics(null); setSyncedLyrics(null) })
       .finally(() => setLoadingLyrics(false))
   }, [track?.id]) // eslint-disable-line react-hooks/exhaustive-deps
 
@@ -182,6 +188,12 @@ export function FullScreenPlayer() {
                 {/* Lyrics */}
                 {loadingLyrics ? (
                   <p className="text-sm text-muted-foreground animate-pulse">Loading lyrics...</p>
+                ) : syncedLyrics ? (
+                  <SyncedLyrics
+                    syncedLyrics={syncedLyrics}
+                    currentTime={state.progress}
+                    onSeek={seek}
+                  />
                 ) : lyrics ? (
                   <div className="w-full max-w-sm">
                     <h3 className="text-sm font-semibold mb-2 text-muted-foreground">Lyrics</h3>

components/music/synced-lyrics.tsx

@@ -0,0 +1,98 @@
+'use client'
+
+import { useMemo, useRef, useEffect } from 'react'
+
+interface LyricLine {
+  time: number // seconds
+  text: string
+}
+
+function parseLRC(lrc: string): LyricLine[] {
+  const lines: LyricLine[] = []
+  for (const raw of lrc.split('\n')) {
+    const match = raw.match(/^\[(\d{2}):(\d{2})\.(\d{2,3})\]\s?(.*)$/)
+    if (!match) continue
+    const mins = parseInt(match[1], 10)
+    const secs = parseInt(match[2], 10)
+    const ms = parseInt(match[3].padEnd(3, '0'), 10)
+    const text = match[4].trim()
+    if (!text) continue
+    lines.push({ time: mins * 60 + secs + ms / 1000, text })
+  }
+  return lines.sort((a, b) => a.time - b.time)
+}
+
+export function SyncedLyrics({
+  syncedLyrics,
+  currentTime,
+  onSeek,
+}: {
+  syncedLyrics: string
+  currentTime: number
+  onSeek?: (time: number) => void
+}) {
+  const lines = useMemo(() => parseLRC(syncedLyrics), [syncedLyrics])
+  const containerRef = useRef<HTMLDivElement>(null)
+  const activeRef = useRef<HTMLButtonElement>(null)
+
+  // Find active line index
+  let activeIndex = -1
+  for (let i = lines.length - 1; i >= 0; i--) {
+    if (currentTime >= lines[i].time) {
+      activeIndex = i
+      break
+    }
+  }
+
+  // Auto-scroll to active line
+  useEffect(() => {
+    if (activeRef.current && containerRef.current) {
+      const container = containerRef.current
+      const el = activeRef.current
+      const containerRect = container.getBoundingClientRect()
+      const elRect = el.getBoundingClientRect()
+
+      // Center the active line in the visible area
+      const targetScroll = el.offsetTop - container.offsetTop - containerRect.height / 2 + elRect.height / 2
+      container.scrollTo({ top: targetScroll, behavior: 'smooth' })
+    }
+  }, [activeIndex])
+
+  if (lines.length === 0) return null
+
+  return (
+    <div className="w-full max-w-sm">
+      <h3 className="text-sm font-semibold mb-3 text-muted-foreground">Lyrics</h3>
+      <div
+        ref={containerRef}
+        className="max-h-[300px] overflow-y-auto scroll-smooth space-y-1 pr-2"
+        style={{ scrollbarWidth: 'thin' }}
+      >
+        {/* Top padding so first line can center */}
+        <div className="h-[120px]" />
+        {lines.map((line, i) => {
+          const isActive = i === activeIndex
+          const isPast = i < activeIndex
+          return (
+            <button
+              key={`${i}-${line.time}`}
+              ref={isActive ? activeRef : undefined}
+              onClick={() => onSeek?.(line.time)}
+              className={`block w-full text-left px-2 py-1.5 rounded-md transition-all duration-300 ${
+                isActive
+                  ? 'text-foreground text-lg font-semibold scale-[1.02]'
+                  : isPast
+                    ? 'text-muted-foreground/40 text-sm'
+                    : 'text-muted-foreground/60 text-sm'
+              } hover:bg-muted/30`}
+            >
+              {line.text}
+            </button>
+          )
+        })}
+        {/* Bottom padding so last line can center */}
+        <div className="h-[120px]" />
+      </div>
+    </div>
+  )
+}