fix: Music autoplay auf Desktop – saubere fadeIn/startPlayback Logik

Refs statt State für started/audible Tracking, fadeIn als eigene
stabile Callback-Funktion, kein verschachteltes Promise-Handling mehr.

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

src/components/MusicPlayer.tsx

@@ -18,6 +18,7 @@ export default function MusicPlayer({ tracks }: { tracks: MediaItem[] }) {
   const activeRef = useRef<'A' | 'B'>('A')
   const fadingRef = useRef(false)
   const startedRef = useRef(false)
+  const audibleRef = useRef(false)
 
   const [userMuted, setUserMuted] = useState(false)
   const [playing, setPlaying] = useState(false)
@@ -31,7 +32,7 @@ export default function MusicPlayer({ tracks }: { tracks: MediaItem[] }) {
     [],
   )
 
-  // ── Crossfade loop ──────────────────────────────────────────────────────
+  // ── Crossfade loop ────────────────────────────────────────────
   const crossfade = useCallback(() => {
     if (fadingRef.current) return
     fadingRef.current = true
@@ -63,15 +64,14 @@ export default function MusicPlayer({ tracks }: { tracks: MediaItem[] }) {
     requestAnimationFrame(step)
   }, [userMuted, getActive, getInactive])
 
-  // Monitor for crossfade trigger
+  // Monitor for crossfade
   useEffect(() => {
     if (!playing || !src) return
     let id: number
     const tick = () => {
       const a = getActive()
       if (a && a.duration) {
-        const remaining = a.duration - a.currentTime
-        if (remaining <= TAIL_SKIP && !fadingRef.current) {
+        if (a.duration - a.currentTime <= TAIL_SKIP && !fadingRef.current) {
           crossfade()
         }
       }
@@ -81,13 +81,10 @@ export default function MusicPlayer({ tracks }: { tracks: MediaItem[] }) {
     return () => cancelAnimationFrame(id)
   }, [playing, src, getActive, crossfade])
 
-  // Fallback if crossfade misses
+  // Fallback loop
   const handleEnded = useCallback(() => {
     const a = getActive()
-    if (a) {
-      a.currentTime = 0
-      a.play().catch(() => {})
-    }
+    if (a) { a.currentTime = 0; a.play().catch(() => {}) }
   }, [getActive])
 
   // Sync volume on mute toggle
@@ -99,74 +96,56 @@ export default function MusicPlayer({ tracks }: { tracks: MediaItem[] }) {
     if (b && !fadingRef.current && !b.paused) b.volume = vol
   }, [userMuted, getActive, getInactive])
 
-  // ── Autoplay strategy ───────────────────────────────────────────────────
-  // Mobile Safari needs play() called *directly* inside a user gesture.
-  // Desktop Chrome allows muted autoplay (volume=0).
-  //
-  // Strategy:
-  // 1. Try silent autoplay immediately (desktop)
-  // 2. On first touch/click, call play() directly in the handler (mobile)
-  // 3. Then fade volume in over 2s
-  useEffect(() => {
-    if (!src) return
-
-    const startAndFade = (a: HTMLAudioElement) => {
-      if (startedRef.current) return
-      startedRef.current = true
-      a.volume = 0
-      a.play().then(() => {
-        setPlaying(true)
-        // Fade in
-        const t0 = performance.now()
-        const fade = () => {
-          const t = Math.min((performance.now() - t0) / FADE_IN_MS, 1)
-          a.volume = VOLUME * t
-          if (t < 1) requestAnimationFrame(fade)
-        }
-        requestAnimationFrame(fade)
-      }).catch(() => {
-        startedRef.current = false
-      })
+  // ── Fade volume from 0 → VOLUME ──────────────────────────────
+  const fadeIn = useCallback(() => {
+    if (audibleRef.current) return
+    audibleRef.current = true
+    const active = activeRef.current === 'A' ? audioA.current : audioB.current
+    if (!active) return
+    const t0 = performance.now()
+    const step = () => {
+      const t = Math.min((performance.now() - t0) / FADE_IN_MS, 1)
+      if (!fadingRef.current) active.volume = VOLUME * t
+      if (t < 1) requestAnimationFrame(step)
     }
+    requestAnimationFrame(step)
+  }, [])
 
-    // Attempt 1: silent autoplay (works on desktop)
+  // ── Start playback (called directly in gesture handler for mobile) ──
+  const startPlayback = useCallback(() => {
+    if (startedRef.current) return
     const a = audioA.current
-    if (a) {
-      a.volume = 0
-      a.play().then(() => {
-        startedRef.current = true
-        setPlaying(true)
-        // Already playing silently, fade in on first interaction
-        const fadeIn = () => {
-          if (!startedRef.current) return
-          const t0 = performance.now()
-          const fade = () => {
-            const active = activeRef.current === 'A' ? audioA.current : audioB.current
-            if (!active) return
-            const t = Math.min((performance.now() - t0) / FADE_IN_MS, 1)
-            if (!fadingRef.current) active.volume = VOLUME * t
-            if (t < 1) requestAnimationFrame(fade)
-          }
-          requestAnimationFrame(fade)
-        }
-        const events = ['scroll', 'click', 'touchstart', 'keydown'] as const
-        events.forEach((e) => window.addEventListener(e, fadeIn, { once: true, passive: true }))
-      }).catch(() => {
-        // Attempt 2: autoplay blocked (mobile) → wait for user gesture
-        // play() MUST be called synchronously inside the handler
-        const onGesture = () => {
-          const el = audioA.current
-          if (el) startAndFade(el)
-          // Clean up other listeners
-          gestureEvents.forEach((e) => document.removeEventListener(e, onGesture))
-        }
-        const gestureEvents = ['click', 'touchstart', 'touchend', 'keydown'] as const
-        gestureEvents.forEach((e) =>
-          document.addEventListener(e, onGesture, { once: true, passive: true })
-        )
-      })
-    }
-  }, [src])
+    if (!a) return
+    startedRef.current = true
+    a.volume = 0
+    a.play().then(() => {
+      setPlaying(true)
+      fadeIn()
+    }).catch(() => { startedRef.current = false })
+  }, [fadeIn])
+
+  // ── Autoplay ─────────────────────────────────────────────────
+  useEffect(() => {
+    if (!src || startedRef.current) return
+    const a = audioA.current
+    if (!a) return
+
+    // Try silent autoplay (desktop allows this)
+    a.volume = 0
+    a.play().then(() => {
+      startedRef.current = true
+      setPlaying(true)
+      // Playing silently — fade in on first interaction
+      const onInteract = () => fadeIn()
+      const events = ['scroll', 'click', 'touchstart', 'keydown'] as const
+      events.forEach((e) => window.addEventListener(e, onInteract, { once: true, passive: true }))
+    }).catch(() => {
+      // Blocked (mobile) — start on first gesture
+      const onGesture = () => startPlayback()
+      const events = ['click', 'touchstart', 'touchend', 'keydown'] as const
+      events.forEach((e) => document.addEventListener(e, onGesture, { once: true, passive: true }))
+    })
+  }, [src, fadeIn, startPlayback])
 
   if (!track || !src) return null