diff --git a/app/static/js/app.jsx b/app/static/js/app.jsx
index 011d2d8..15b64f1 100644
--- a/app/static/js/app.jsx
+++ b/app/static/js/app.jsx
@@ -20867,7 +20867,11 @@ const App = () => {
   const ensureMasteringRouting = () => {
     try {
       const _s = window.currentMasteringSettings;
-      if (!_s || !masterBus || !audioCtx) return;
+      if (!_s) return;
+      // Đảm bảo audioCtx + masterBus đã tồn tại trước khi sync (lần preview
+      // đầu tiên audio chưa init → getAudioContext tạo ngay)
+      getAudioContext();
+      if (!masterBus || !audioCtx) return;
       toggleMasteringOnMaster(!!_s.masterConnected, !!_s.isBypassed);
       applyMasteringSettings(_s);
       updateSfRouting();
diff --git a/app/static/js/app.precompiled.js b/app/static/js/app.precompiled.js
index 2962a84..889012e 100644
--- a/app/static/js/app.precompiled.js
+++ b/app/static/js/app.precompiled.js
@@ -1290,7 +1290,9 @@ const _b=effMidiBypass(t);node.sfRouteGain.gain.value=_b?0:1;node.sfDryGain.gain
 // chạy khi bắt đầu preview. Hàm này ép đồng bộ 3 lớp (graph theo trạng thái
 // hiện tại — early-return nếu đã đúng; tham số module; route SF + route
 // gains) — gọi tại mọi điểm preview → âm preview LUÔN qua mastering khi bật.
-const ensureMasteringRouting=()=>{try{const _s=window.currentMasteringSettings;if(!_s||!masterBus||!audioCtx)return;toggleMasteringOnMaster(!!_s.masterConnected,!!_s.isBypassed);applyMasteringSettings(_s);updateSfRouting();}catch(e){console.warn('ensureMasteringRouting error:',e);}};const ensureMasteringRoutingRef=useRef(null);ensureMasteringRoutingRef.current=ensureMasteringRouting;window.__ensureMasteringRouting=ensureMasteringRouting;// ── MIDI preview cache (bounce nhanh offline) ──
+const ensureMasteringRouting=()=>{try{const _s=window.currentMasteringSettings;if(!_s)return;// Đảm bảo audioCtx + masterBus đã tồn tại trước khi sync (lần preview
+// đầu tiên audio chưa init → getAudioContext tạo ngay)
+getAudioContext();if(!masterBus||!audioCtx)return;toggleMasteringOnMaster(!!_s.masterConnected,!!_s.isBypassed);applyMasteringSettings(_s);updateSfRouting();}catch(e){console.warn('ensureMasteringRouting error:',e);}};const ensureMasteringRoutingRef=useRef(null);ensureMasteringRoutingRef.current=ensureMasteringRouting;window.__ensureMasteringRouting=ensureMasteringRouting;// ── MIDI preview cache (bounce nhanh offline) ──
 // Khi preview: capture tiếng đàn (SF output — pre track-FX) vào cache theo
 // track. Khi export: nếu cache đủ độ dài → render OFFLINE NHANH bằng cache
 // (qua FX Rack + Mastering như playback) — không cần chờ bounce realtime.
diff --git a/app/templates/index.html b/app/templates/index.html
index 9b218c6..dc32e5a 100644
--- a/app/templates/index.html
+++ b/app/templates/index.html
@@ -31,12 +31,12 @@
     <script src="https://unpkg.com/react@18.3.1/umd/react.production.min.js"></script>
     <script src="https://unpkg.com/react-dom@18.3.1/umd/react-dom.production.min.js"></script>
     <script src="/static/js/services/fluidsynthLoader.js?v=202607271245"></script>
-    <script src="/static/js/services/runtime.js?v=202608101400"></script>
-    <script src="/static/js/services/api.js?v=202608101400"></script>
+    <script src="/static/js/services/runtime.js?v=202608101500"></script>
+    <script src="/static/js/services/api.js?v=202608101500"></script>
     <script src="/static/js/services/audioEngine.js?v=202607271016"></script>
     <script src="/static/js/services/storage.js?v=202608038200"></script>
     <script src="/static/js/services/soundfontStorage.js?v=202607271016"></script>
-    <script src="/static/js/services/soundfontPlayer.js?v=202608101400"></script>
+    <script src="/static/js/services/soundfontPlayer.js?v=202608101500"></script>
     <script src="/static/js/services/aiGateway.js?v=202608037200"></script>
     <script src="/static/js/services/dawCommandDispatcher.js?v=202607271016"></script>
     <script src="/static/js/services/pianoRollTabService.js?v=202607272044"></script>
@@ -44,7 +44,7 @@
     <script src="/static/js/services/midiExtractor.js?v=202607281052"></script>
     <script src="/static/js/services/promptTemplateManager.js?v=202607281039"></script>
     <script src="/static/js/services/undoRedoEngine.js?v=202607290941"></script>
-    <script src="/static/js/app.precompiled.js?v=202608101400" defer></script>
+    <script src="/static/js/app.precompiled.js?v=202608101500" defer></script>
     <link rel="stylesheet" href="/static/css/styles.css?v=202607271016">
     <style>
         :root {