fix(playback): het fade-out dai dang khi stop - restore gain LUON (ke ca stale/play moi trong cua so fade) qua pending fade session, huy fade ngay khi play moi (het dip 200ms); sync 6 ban JS + index.html ?v=202608181840

app/static/js/app.jsx

@@ -279,6 +279,22 @@ const stopAllNativeSfNotes = () => {
 // Epoch guard: stop/rebuild tăng _nativePlayEpoch → mọi render pending của
 // lần play cũ resolve nhưng bị skip (không duplicate schedule).
 let _nativePlayEpoch = 0;
+// V17: fade session dang treo (gain ramp FADE_MS) — restore khi play moi /
+// stop moi / doHardStop de gain KHONG bi ket ~0.0001 (root cause "am bi fade out").
+let _pendingFadeSession = null;
+const restorePendingFadeSession = () => {
+  if (!_pendingFadeSession) return;
+  try {
+    const t = getAudioContext().currentTime;
+    _pendingFadeSession.fadedGains.forEach(g => {
+      try { g.node.gain.cancelScheduledValues(t); g.node.gain.setValueAtTime(g.prev, t); } catch (e) {}
+    });
+    if (_pendingFadeSession.bridgeGainNode) {
+      try { _pendingFadeSession.bridgeGainNode.gain.cancelScheduledValues(t); _pendingFadeSession.bridgeGainNode.gain.setValueAtTime(1.0, t); } catch (e) {}
+    }
+  } catch (e) {}
+  _pendingFadeSession = null;
+};
 const _nativeTrackUrls = {};
 const _nativeTrackPending = {};
 // ── MIDI overlap cleanup + polyphony gain (spec midi_polyphony_loudness) ─
@@ -21487,6 +21503,7 @@ const App = () => {
   const startSubTabPlayback = (st, offsetWallTime) => {
     const context = getAudioContext();
     _nativePlayEpoch++; // new play — vô hiệu doHardStop đang fade
+    restorePendingFadeSession(); // V17: huy fade dang treo — replay khong bi dip gain
     if (!st.buffer) {
       st.buffer = context.createBuffer(1, 128, context.sampleRate);
     }
@@ -22679,6 +22696,7 @@ const App = () => {
   const startTrackPlayback = offsetTime => {
     const context = getAudioContext();
     _nativePlayEpoch++; // new play — vô hiệu doHardStop đang fade (play trong cửa sổ 80ms)
+    restorePendingFadeSession(); // V17: huy fade dang treo — replay khong bi dip gain
     // D2: bridge active -> báo transport PLAY (bridge flush note-off cũ + đồng
     // bộ timeline; A13 C++ xử lý arg1=playheadSamples sau này).
     if (window.NativeBridgeService && window.NativeBridgeService.isBridgeConnected) {
@@ -23129,6 +23147,7 @@ const App = () => {
     if (st.type !== 'PIANO_ROLL') return;
     const context = getAudioContext();
     _nativePlayEpoch++; // new play — vô hiệu doHardStop đang fade
+    restorePendingFadeSession(); // V17: huy fade dang treo — replay khong bi dip gain
     // V10: piano roll loop restart cũng gọi stopAllPlayback() trước (STOP#1 →
     // bridge transportStopped=true) → mọi note-on bị drop nếu không PLAY lại.
     // Hủy STOP#2 (150ms) + báo PLAY để bridge nhận note mới (loop liên tục).
@@ -23363,6 +23382,10 @@ const App = () => {
     } catch (e) {}
     let bridgeGainNode = null;
     if (fade && ctx) {
+      // V17: restore fade session cu TRUOC khi capture prev — double-stop trong
+      // cua so fade: neu khong, session cu stale -> bo restore, session moi capture
+      // prev giua ramp (vd 0.5) -> restore sai -> gain ket.
+      restorePendingFadeSession();
       try {
         const now = ctx.currentTime;
         capturedNodes.forEach(n => {
@@ -23383,6 +23406,7 @@ const App = () => {
           }
         }
       } catch (e) { console.warn('[Stop] fade setup error:', e); }
+      _pendingFadeSession = { fadedGains, bridgeGainNode, stopEpoch };
     }
     const doHardStop = () => {
       try {
@@ -23393,6 +23417,12 @@ const App = () => {
         capturedNodes.forEach(n => {
           if (n.fxStopFn) { try { n.fxStopFn(); } catch (e) {} }
         });
+        // V17: restore gain LUON — play moi trong cua so fade (stale) truoc day bo qua
+        // restore -> track/bridge gain ket 0.0001 -> moi am sau bi fade-out dai dang.
+        // Chi skip khi co fade session MOI hon (session nay het pending — session moi tu restore).
+        if (_pendingFadeSession && _pendingFadeSession.stopEpoch === stopEpoch) {
+          restorePendingFadeSession();
+        }
         if (stale) return; // play mới đang chạy — không dừng bridge/SF của nó
         stopMidiCapture();
         stopAllNativeSfNotes(); stopAllNativeVstNotes();
@@ -23418,16 +23448,6 @@ const App = () => {
       } catch (e) {
         console.warn('[Stop] stopAllPlayback error:', e);
       }
-      // Restore gain về giá trị cũ — play lần sau không bị câm/đổi volume.
-      try {
-        const t = getAudioContext().currentTime;
-        fadedGains.forEach(g => {
-          try { g.node.gain.cancelScheduledValues(t); g.node.gain.setValueAtTime(g.prev, t); } catch (e) {}
-        });
-        if (bridgeGainNode) {
-          try { bridgeGainNode.gain.cancelScheduledValues(t); bridgeGainNode.gain.setValueAtTime(1.0, t); } catch (e) {}
-        }
-      } catch (e) {}
     };
     if (fade && ctx) {
       try { setTimeout(doHardStop, FADE_MS); } catch (e) { doHardStop(); }