diff --git a/app/static/js/app.jsx b/app/static/js/app.jsx
index 0368017..828b6ff 100644
--- a/app/static/js/app.jsx
+++ b/app/static/js/app.jsx
@@ -18666,13 +18666,13 @@ const App = () => {
                     var bPrArmed = {};
                     if (_isPrTabNow) {
                       try {
-                        (subTabsRef.current || []).forEach(function (s) {
-                          if (s.type === 'PIANO_ROLL' && s.isArmed && s.trackId) bPrArmed[s.trackId] = true;
-                        });
+                        // V45.25: chi sub-tab PR dang active; khong gom ARM sub-tab khac.
+                        var _actPrSub = (subTabsRef.current || []).find(function (s) { return s.id === activeTabRef.current; });
+                        if (_actPrSub && _actPrSub.type === 'PIANO_ROLL' && _actPrSub.trackId) bPrArmed[_actPrSub.trackId] = true;
                       } catch (e) {}
                     }
                     bTracks.forEach(function (bt) {
-                      if (!bt.isArmed && !bPrArmed[bt.id]) return;
+                      if (_isPrTabNow ? !bPrArmed[bt.id] : !bt.isArmed) return;
                       // V45.24: PR preview doc lap voi mute/solo MAIN/SECTION —
                       // khoi phuc volume track (bo qua mute/solo) khi o PR tab.
                       if (_isPrTabNow) { try { ensureTrackPrAudible(bt, bTracks, activeTrackNodesRef.current[bt.id]); } catch (e) {} }
@@ -18686,8 +18686,13 @@ const App = () => {
                     });
                   } else if (window.SonicSF) {
                      var allTracks = activeTracksRef.current || [];
-                     var arSubs = _isPrTabNow && subTabsRef && subTabsRef.current ? subTabsRef.current.filter(function(s) { return s.type === 'PIANO_ROLL' && s.isArmed; }) : [];
-                     var armedTracks = allTracks.filter(function(t) { return t.isArmed; });
+                     var arSubs = [];
+                     // V45.25: chi sub-tab PR dang active; khong gom ARM sub-tab khac.
+                     if (_isPrTabNow && subTabsRef && subTabsRef.current) {
+                       var _actPrSub = subTabsRef.current.find(function(s) { return s.id === activeTabRef.current; });
+                       if (_actPrSub && _actPrSub.type === 'PIANO_ROLL' && _actPrSub.trackId) arSubs.push(_actPrSub);
+                     }
+                     var armedTracks = _isPrTabNow ? [] : allTracks.filter(function(t) { return t.isArmed; });
                      // Piano Roll arming has priority: route to each armed sub-tab's parent track
                      if (arSubs.length > 0) {
                        arSubs.forEach(function(as) {
@@ -23920,18 +23925,18 @@ const App = () => {
     const _prTabNow = (subTabsRef.current || []).find(function (s) { return s.id === activeTabRef.current; });
     const _isPrTabNow = !!(_prTabNow && _prTabNow.type === 'PIANO_ROLL');
     const prArmedIds = {};
+    // V45.25: PR tab preview chi track dang edit (sub-tab active) - bat ke ARM.
+    // ARM tu sub-tab PR khac / track MAIN KHONG leak sang PR tab nay.
     try {
       if (_isPrTabNow) {
-        (subTabsRef.current || []).forEach(function (s) {
-          if (s.type === 'PIANO_ROLL' && s.isArmed && s.trackId) prArmedIds[s.trackId] = true;
-        });
+        if (_prTabNow.trackId) prArmedIds[_prTabNow.trackId] = true;
       }
     } catch (e) {}
-    const armed = allTracks.filter(function (t) { return t.isArmed || prArmedIds[t.id]; });
-    const targets = armed.length ? armed : (_isPrTabNow ? allTracks : []);
-    if (!armed.length && !window.__vkbNoArmToast) {
+    const armed = allTracks.filter(function (t) { return t.isArmed; });
+    const targets = _isPrTabNow ? allTracks.filter(function (t) { return prArmedIds[t.id]; }) : (armed.length ? armed : []);
+    if (!_isPrTabNow && !armed.length && !window.__vkbNoArmToast) {
       window.__vkbNoArmToast = true;
-      showToast(_isPrTabNow ? 'Không có track nào ARM — chơi vào tất cả track.' : 'Không có track nào ARM — preview MIDI câm (MAIN/SECTION).', 'info');
+      showToast('Không có track nào ARM — preview MIDI câm (MAIN/SECTION).', 'info');
     }
     // DIAG Bug 3/4 (preview khong am): trang thai routing tai note-on.
     try {
diff --git a/app/static/js/app.precompiled.js b/app/static/js/app.precompiled.js
index a00c965..b3194a5 100644
--- a/app/static/js/app.precompiled.js
+++ b/app/static/js/app.precompiled.js
@@ -344,7 +344,7 @@ else if(fxRt.chainKey!==ck){fxRtSetChain(chain);fxRt.chainKey=ck;return;}else re
 // node → bypass vô hiệu. Mỗi fxRtStop() bump startToken → mọi checkpoint
 // dưới đây thấy mismatch → hủy session vừa tạo, không nối node.
 const token=++fxRt.startToken;fxRt.starting=true;const ctx=getAudioContext();if(!ctx||!ctx.audioWorklet||!masterBus||!masterBus.output||!masterBus.analyser||!masterBus.masterFxGain||!masterBus.masterFxDryGain)return;const chainPayload=chain.map(s=>s.type==='vst3'?{type:'vst3',path:s.path,name:s.name||s.path,preset_b64:s.preset_b64||'',bypass:!!s.bypass||!!(window.currentMasteringSettings||{}).vstBypass}:{type:'builtin',id:s.type,params:s.params&&Object.keys(s.params).length?s.params:{},bypass:!!s.bypass});let st;try{st=await window.SonicAPI.fxRealtimeStart({fx_chain:chainPayload,sample_rate:ctx.sampleRate||44100});}catch(e){console.warn('[FX RT] start fail:',e);showToast('Không khởi động VST FX realtime: '+(e.message||e),'warning');fxRt.starting=false;return;}if(token!==fxRt.startToken){// Bypass/stop giữa lúc engine đang load chain — hủy session vừa tạo.
-console.warn('[FX RT] start cancelled mid-flight — session stopped');try{window.SonicAPI.fxRealtimeStop({session_id:st.session_id}).catch(()=>{});}catch(e2){}fxRt.starting=false;return;}fxRt.sessionId=st.session_id;fxRtGuiPushShm();try{await ctx.audioWorklet.addModule(`${API_BASE_URL}/static/js/sf-fx-realtime.js?v=202608311725`);if(token!==fxRt.startToken){fxRt.starting=false;return;}fxRt.node=new AudioWorkletNode(ctx,'sf-fx-realtime',{numberOfInputs:1,numberOfOutputs:1,outputChannelCount:[2]});const u=new URL(API_BASE_URL);const wsProto=u.protocol==='https:'?'wss://':'ws://';// WS to 'localhost' bi tre ~300ms: Chromium thu ::1 truoc (Windows khong
+console.warn('[FX RT] start cancelled mid-flight — session stopped');try{window.SonicAPI.fxRealtimeStop({session_id:st.session_id}).catch(()=>{});}catch(e2){}fxRt.starting=false;return;}fxRt.sessionId=st.session_id;fxRtGuiPushShm();try{await ctx.audioWorklet.addModule(`${API_BASE_URL}/static/js/sf-fx-realtime.js?v=202608311739`);if(token!==fxRt.startToken){fxRt.starting=false;return;}fxRt.node=new AudioWorkletNode(ctx,'sf-fx-realtime',{numberOfInputs:1,numberOfOutputs:1,outputChannelCount:[2]});const u=new URL(API_BASE_URL);const wsProto=u.protocol==='https:'?'wss://':'ws://';// WS to 'localhost' bi tre ~300ms: Chromium thu ::1 truoc (Windows khong
 // co listener IPv6 -> SYN hang ~2s) roi moi fallback 127.0.0.1. Dung
 // thang 127.0.0.1 (loopback) -> WS open ~5ms. Server chap nhan loopback.
 const wsHost=u.hostname==='localhost'||u.hostname==='::1'?'127.0.0.1'+(u.port?':'+u.port:''):u.host;const tok=localStorage.getItem('sonic_token')||'';const wsUrl=`${wsProto}${wsHost}${st.ws_url}${tok?'?token='+encodeURIComponent(tok):''}`;const ws=new WebSocket(wsUrl);fxRt.ws=ws;ws.binaryType='arraybuffer';ws.onopen=()=>{if(token!==fxRt.startToken){try{ws.close();}catch(e){}fxRt.starting=false;return;}fxRt.active=true;fxRt.flushing=false;fxRt.starting=false;fxRt.inQueue=[];// bỏ audio stale sản xuất trước khi WS open (~4s load VST) — hết lag khởi đầu
@@ -1301,9 +1301,11 @@ if(window.SonicMidiRouter&&window.SonicMidiRouter.isBridgeActive()){// D1: bridg
 var bTracks=activeTracksRef.current||[];// ARM piano roll (sub-tab isArmed, cuc bo) cung tinh nhu ARM
 // track - preview note tu piano roll tab phai toi track dang
 // edit du track main KHONG ARM (ARM piano roll khong truyen).
-var bPrArmed={};if(_isPrTabNow){try{(subTabsRef.current||[]).forEach(function(s){if(s.type==='PIANO_ROLL'&&s.isArmed&&s.trackId)bPrArmed[s.trackId]=true;});}catch(e){}}bTracks.forEach(function(bt){if(!bt.isArmed&&!bPrArmed[bt.id])return;// V45.24: PR preview doc lap voi mute/solo MAIN/SECTION —
+var bPrArmed={};if(_isPrTabNow){try{// V45.25: chi sub-tab PR dang active; khong gom ARM sub-tab khac.
+var _actPrSub=(subTabsRef.current||[]).find(function(s){return s.id===activeTabRef.current;});if(_actPrSub&&_actPrSub.type==='PIANO_ROLL'&&_actPrSub.trackId)bPrArmed[_actPrSub.trackId]=true;}catch(e){}}bTracks.forEach(function(bt){if(_isPrTabNow?!bPrArmed[bt.id]:!bt.isArmed)return;// V45.24: PR preview doc lap voi mute/solo MAIN/SECTION —
 // khoi phuc volume track (bo qua mute/solo) khi o PR tab.
-if(_isPrTabNow){try{ensureTrackPrAudible(bt,bTracks,activeTrackNodesRef.current[bt.id]);}catch(e){}}if(window.triggerMidiVuActivity){window.triggerMidiVuActivity(bt.id,scaledVel);}try{heldMidiNotesRef.current[bt.id]=(heldMidiNotesRef.current[bt.id]||0)+1;}catch(err){}try{window.SonicMidiRouter.pushEvent({cmd:'NOTE_ON',channel:bt.id,pitch:pitch,velocity:scaledVel/127,percussion:!!(bt.synth_engine&&bt.synth_engine.soundfont_bank===128),live:true});}catch(e){}});}else if(window.SonicSF){var allTracks=activeTracksRef.current||[];var arSubs=_isPrTabNow&&subTabsRef&&subTabsRef.current?subTabsRef.current.filter(function(s){return s.type==='PIANO_ROLL'&&s.isArmed;}):[];var armedTracks=allTracks.filter(function(t){return t.isArmed;});// Piano Roll arming has priority: route to each armed sub-tab's parent track
+if(_isPrTabNow){try{ensureTrackPrAudible(bt,bTracks,activeTrackNodesRef.current[bt.id]);}catch(e){}}if(window.triggerMidiVuActivity){window.triggerMidiVuActivity(bt.id,scaledVel);}try{heldMidiNotesRef.current[bt.id]=(heldMidiNotesRef.current[bt.id]||0)+1;}catch(err){}try{window.SonicMidiRouter.pushEvent({cmd:'NOTE_ON',channel:bt.id,pitch:pitch,velocity:scaledVel/127,percussion:!!(bt.synth_engine&&bt.synth_engine.soundfont_bank===128),live:true});}catch(e){}});}else if(window.SonicSF){var allTracks=activeTracksRef.current||[];var arSubs=[];// V45.25: chi sub-tab PR dang active; khong gom ARM sub-tab khac.
+if(_isPrTabNow&&subTabsRef&&subTabsRef.current){var _actPrSub=subTabsRef.current.find(function(s){return s.id===activeTabRef.current;});if(_actPrSub&&_actPrSub.type==='PIANO_ROLL'&&_actPrSub.trackId)arSubs.push(_actPrSub);}var armedTracks=_isPrTabNow?[]:allTracks.filter(function(t){return t.isArmed;});// Piano Roll arming has priority: route to each armed sub-tab's parent track
 if(arSubs.length>0){arSubs.forEach(function(as){var asTrk=allTracks.find(function(t){return t.id===as.trackId;});// V45.24: PR preview doc lap voi mute/solo MAIN/SECTION.
 if(_isPrTabNow&&asTrk){try{ensureTrackPrAudible(asTrk,allTracks,activeTrackNodesRef.current[as.trackId]);}catch(e){}}var asCh=asTrk?assignTrackMidiChannel(asTrk,allTracks):0;var asProg=as.instrumentProgram;var asSe=as.synth_engine;if(window.triggerMidiVuActivity){window.triggerMidiVuActivity(as.trackId,scaledVel);}// Giữ VU theo trường độ: tăng counter note đang giữ
 // (tick giữ peak cho tới khi note-off)
@@ -1801,7 +1803,9 @@ const showToast=(text,type='info',actionText=null,onActionClick=null)=>{if(toast
 const vkbNoteOn=(pitch,vel)=>{try{if(window.__ensureMasteringRouting)window.__ensureMasteringRouting();}catch(er){}const allTracks=activeTracksRef.current||[];// V45.19 Bug 2: ARM piano roll chi tac dung khi DANG o PIANO_ROLL tab. O
 // MAIN/SECTION chi tinh track isArmed that su; ARM tu piano roll KHONG truyen
 // sang. Khong track nao ARM o MAIN/SECTION -> targets rong -> preview cam.
-const _prTabNow=(subTabsRef.current||[]).find(function(s){return s.id===activeTabRef.current;});const _isPrTabNow=!!(_prTabNow&&_prTabNow.type==='PIANO_ROLL');const prArmedIds={};try{if(_isPrTabNow){(subTabsRef.current||[]).forEach(function(s){if(s.type==='PIANO_ROLL'&&s.isArmed&&s.trackId)prArmedIds[s.trackId]=true;});}}catch(e){}const armed=allTracks.filter(function(t){return t.isArmed||prArmedIds[t.id];});const targets=armed.length?armed:_isPrTabNow?allTracks:[];if(!armed.length&&!window.__vkbNoArmToast){window.__vkbNoArmToast=true;showToast(_isPrTabNow?'Không có track nào ARM — chơi vào tất cả track.':'Không có track nào ARM — preview MIDI câm (MAIN/SECTION).','info');}// DIAG Bug 3/4 (preview khong am): trang thai routing tai note-on.
+const _prTabNow=(subTabsRef.current||[]).find(function(s){return s.id===activeTabRef.current;});const _isPrTabNow=!!(_prTabNow&&_prTabNow.type==='PIANO_ROLL');const prArmedIds={};// V45.25: PR tab preview chi track dang edit (sub-tab active) - bat ke ARM.
+// ARM tu sub-tab PR khac / track MAIN KHONG leak sang PR tab nay.
+try{if(_isPrTabNow){if(_prTabNow.trackId)prArmedIds[_prTabNow.trackId]=true;}}catch(e){}const armed=allTracks.filter(function(t){return t.isArmed;});const targets=_isPrTabNow?allTracks.filter(function(t){return prArmedIds[t.id];}):armed.length?armed:[];if(!_isPrTabNow&&!armed.length&&!window.__vkbNoArmToast){window.__vkbNoArmToast=true;showToast('Không có track nào ARM — preview MIDI câm (MAIN/SECTION).','info');}// DIAG Bug 3/4 (preview khong am): trang thai routing tai note-on.
 try{let _pdDest='none';if(window.AudioRoutingEngine&&window.AudioRoutingEngine._connected){_pdDest=window.AudioRoutingEngine._dest&&window.AudioRoutingEngine._dest.constructor?window.AudioRoutingEngine._dest.constructor.name:'null';_pdDest+='/'+window.AudioRoutingEngine._trackId;}else{_pdDest='NOT_CONNECTED';}const _pdD=window.BridgeAudioNode?window.BridgeAudioNode.getDiag():null;const _pdTab=activeTabRef.current;const _pdSub=subTabsRef.current?(subTabsRef.current.find(s=>s.id===_pdTab)||{}).type:null;_dbgLog('preview_diag','armed='+armed.length+' trg='+targets.length+' prTab='+(_isPrTabNow?1:0)+' tab='+_pdTab+' sub='+(_pdSub||'none')+' play='+(isPlayingRef.current?1:0)+' br='+(window.SonicMidiRouter&&window.SonicMidiRouter.isBridgeActive()?1:0)+' fxRt='+(fxRt.active?1:0)+' dest='+_pdDest+' bd='+(_pdD?'i='+_pdD.initialized+' wl='+_pdD.useWorklet+' nd='+_pdD.hasWorkletNode+' pre='+_pdD.preBufferLen+' ch='+_pdD.chunksLen+' g='+_pdD.gain:'MISSING')+' mb='+!!masterBus);}catch(e){}// DIAG Bug 3/4: arm bo dem audio frames (500ms sau note-on) de biet
 // engine co gui audio ve JS khong (tach engine vs JS routing).
 try{window.__dbgPreviewAudioArmed={count:0,nz:0,t0:performance.now()};}catch(e){}activeMidiPitchesRef.current.add(pitch);setActiveMidiPitches(new Set(activeMidiPitchesRef.current));vkbHeldRef.current.add(pitch);targets.forEach(function(t){// V45.24: PR preview doc lap voi mute/solo MAIN/SECTION — khoi phuc
@@ -1992,7 +1996,7 @@ fxRtTrackReconcile(trackId,node,track);}catch(e){console.warn('rebuildTrackFxGra
 // Cần activeTrackNodesRef/isPlayingRef. Session giống master (fxRtStart):
 // fetch start → AudioWorkletNode 'sf-fx-realtime' → WS; WS open → splice
 // worklet vào chain hiện tại (đọc mods MỚI NHẤT — an toàn với rebuild).
-const fxRtTrackStart=async(trackId,track,path)=>{const key=trackId+':'+path;const chain=fxRtTrackChain(track);if(!chain.length)return;if(fxRtTracks[key]){if(!fxRtTracks[key].node||fxRtTracks[key].node.context!==getAudioContext())fxRtTrackStop(trackId,path,true);else return;}const ctx=getAudioContext();if(!ctx||!ctx.audioWorklet)return;const chainPayload=chain.map(s=>s.type==='vst3'?{type:'vst3',path:s.path,name:s.name||s.path,preset_b64:s.preset_b64||'',bypass:!!s.bypass||!!(track&&track.vstFxBypass)}:{type:'builtin',id:s.type,params:s.params&&Object.keys(s.params).length?s.params:{},bypass:!!s.bypass});let st;try{st=await window.SonicAPI.fxRealtimeStart({fx_chain:chainPayload,sample_rate:ctx.sampleRate||44100});}catch(e){console.warn('[FX RT track] start fail',trackId,path,e);return;}const entry={sessionId:st.session_id,ws:null,node:null,ready:false,path,spliced:null,chainKey:fxRtTrackChainKey(chain)+'|vb:'+(track&&track.vstFxBypass?'1':'0'),paramsBySlot:chain.map(s=>fxRtEntryParams(s,null)),inQueue:[],pumpTimer:null,lastInSent:0,flushing:false,flushTimer:null};fxRtTracks[key]=entry;fxRtGuiPushShm();try{await ctx.audioWorklet.addModule(`${API_BASE_URL}/static/js/sf-fx-realtime.js?v=202608311725`);const node=new AudioWorkletNode(ctx,'sf-fx-realtime',{numberOfInputs:1,numberOfOutputs:1,outputChannelCount:[2]});entry.node=node;const u=new URL(API_BASE_URL);const wsProto=u.protocol==='https:'?'wss://':'ws://';// WS to 'localhost' bi tre ~300ms (Chromium thu ::1 truoc roi fallback) - dung 127.0.0.1
+const fxRtTrackStart=async(trackId,track,path)=>{const key=trackId+':'+path;const chain=fxRtTrackChain(track);if(!chain.length)return;if(fxRtTracks[key]){if(!fxRtTracks[key].node||fxRtTracks[key].node.context!==getAudioContext())fxRtTrackStop(trackId,path,true);else return;}const ctx=getAudioContext();if(!ctx||!ctx.audioWorklet)return;const chainPayload=chain.map(s=>s.type==='vst3'?{type:'vst3',path:s.path,name:s.name||s.path,preset_b64:s.preset_b64||'',bypass:!!s.bypass||!!(track&&track.vstFxBypass)}:{type:'builtin',id:s.type,params:s.params&&Object.keys(s.params).length?s.params:{},bypass:!!s.bypass});let st;try{st=await window.SonicAPI.fxRealtimeStart({fx_chain:chainPayload,sample_rate:ctx.sampleRate||44100});}catch(e){console.warn('[FX RT track] start fail',trackId,path,e);return;}const entry={sessionId:st.session_id,ws:null,node:null,ready:false,path,spliced:null,chainKey:fxRtTrackChainKey(chain)+'|vb:'+(track&&track.vstFxBypass?'1':'0'),paramsBySlot:chain.map(s=>fxRtEntryParams(s,null)),inQueue:[],pumpTimer:null,lastInSent:0,flushing:false,flushTimer:null};fxRtTracks[key]=entry;fxRtGuiPushShm();try{await ctx.audioWorklet.addModule(`${API_BASE_URL}/static/js/sf-fx-realtime.js?v=202608311739`);const node=new AudioWorkletNode(ctx,'sf-fx-realtime',{numberOfInputs:1,numberOfOutputs:1,outputChannelCount:[2]});entry.node=node;const u=new URL(API_BASE_URL);const wsProto=u.protocol==='https:'?'wss://':'ws://';// WS to 'localhost' bi tre ~300ms (Chromium thu ::1 truoc roi fallback) - dung 127.0.0.1
 const wsHost=u.hostname==='localhost'||u.hostname==='::1'?'127.0.0.1'+(u.port?':'+u.port:''):u.host;const tok=localStorage.getItem('sonic_token')||'';const ws=new WebSocket(`${wsProto}${wsHost}${st.ws_url}${tok?'?token='+encodeURIComponent(tok):''}`);entry.ws=ws;ws.binaryType='arraybuffer';ws.onopen=()=>{entry.ready=true;entry.inQueue=[];// bỏ audio stale trước khi WS open — hết lag khởi đầu
 fxRtTrackSplice(trackId,path);try{(entry.paramsBySlot||[]).forEach((pl,slot)=>pl.forEach(p=>ws.send(JSON.stringify({cmd:'set_param',slot,key:p.key,value:p.value}))));}catch(e){}};ws.onmessage=ev=>{if(typeof ev.data==='string'){try{const d=JSON.parse(ev.data);if(d&&d.cmd==='flush_done'){entry.flushing=false;if(entry.flushTimer){clearTimeout(entry.flushTimer);entry.flushTimer=null;}if(entry.node)entry.node.port.postMessage({type:'flush_done'});}}catch(e){}return;}if(!(ev.data instanceof ArrayBuffer)||!entry.node)return;if(entry.flushing)return;// V24: output stale trong luc flush — drop
 const f=new Float32Array(ev.data);const half=f.length/2;const l=new Float32Array(half);const r=new Float32Array(half);for(let i=0;i<half;i++){l[i]=f[i*2];r[i]=f[i*2+1];}entry.node.port.postMessage({type:'out',l,r});};ws.onclose=()=>fxRtTrackStop(trackId,path,true);ws.onerror=()=>{try{ws.close();}catch(e){}};entry.node.port.onmessage=ev=>{const d=ev.data;if(!d||!entry.ws)return;if(d.type==='flush'){// V24: nhu master — worklet underrun-resume → flush engine ring
diff --git a/app/templates/index.html b/app/templates/index.html
index 71ec9c8..b9db6b4 100644
--- a/app/templates/index.html
+++ b/app/templates/index.html
@@ -51,7 +51,7 @@
     <script src="/static/js/services/promptTemplateManager.js?v=202608290945"></script>
     <script src="/static/js/services/undoRedoEngine.js?v=202608290945"></script>
     <script src="/static/js/services/chordTheory.js?v=202608290945"></script>
-    <script src="/static/js/app.precompiled.js?v=202608311725" defer></script>
+    <script src="/static/js/app.precompiled.js?v=202608311739" defer></script>
     <link rel="stylesheet" href="/static/css/styles.css?v=202608290945">
     <style>
         :root {