V42+V42A: fix seam click khi loop master FX — worklet wrap crossfade (tail->head) + native WebAudio loop cho bypass (het click beat 0); dip bypass 5ms; PDC playhead freeze/snap

app/static/js/services/bridgeAudioNode.js

@@ -31,7 +31,7 @@
       console.warn('[BridgeAudioNode] AudioWorklet unavailable — ScriptProcessor fallback');
       return false;
     }
-    var url = '/static/js/services/bridgeAudioWorklet.js?v=202608152200';
+    var url = '/static/js/services/bridgeAudioWorklet.js?v=202608272301';
     _ctx.audioWorklet.addModule(url).then(function () {
       if (!_initialized) return; // disconnect() happened while loading
       if (_useWorklet) return;   // already set up (init retry)
@@ -49,12 +49,15 @@
           _workletNode.port.postMessage({ type: 'audio', l: b.l, r: b.r });
         }
         console.log('[BridgeAudioNode] AudioWorklet active');
+        try { if (window.__dbgLog) window.__dbgLog('worklet', 'active pre=' + _preBuffer.length); } catch (e) {}
       } catch (err) {
         console.warn('[BridgeAudioNode] AudioWorkletNode failed — ScriptProcessor fallback', err);
         _useWorklet = false;
+        try { if (window.__dbgLog) window.__dbgLog('worklet', 'NODE_FAIL'); } catch (e) {}
       }
     }).catch(function (err) {
       console.warn('[BridgeAudioNode] addModule failed — ScriptProcessor fallback', err);
+      try { if (window.__dbgLog) window.__dbgLog('worklet', 'MODULE_FAIL'); } catch (e) {}
     });
     return true; // pending — worklet may become active later
   }
@@ -157,6 +160,16 @@
       _dest = dest;
     },
     disconnect: disconnect,
-    isReady: function () { return _initialized; }
+    isReady: function () { return _initialized; },
+    getDiag: function () {
+      return {
+        initialized: _initialized,
+        useWorklet: _useWorklet,
+        hasWorkletNode: !!_workletNode,
+        preBufferLen: _preBuffer.length,
+        chunksLen: _chunks.length,
+        gain: _gainNode ? _gainNode.gain.value : -1
+      };
+    }
   };
 })();

app/static/js/services/bridgeAudioWorklet.js

@@ -1,6 +1,8 @@
 // app/static/js/services/bridgeAudioWorklet.js
 // VSTi crackle fix: audio sink chay tren audio thread (khong jank main thread).
-// - Ring block 256 mau, toi da 64 block (~371ms @48k) — hap thu jitter pump.
+// - Ring block 256 mau, toi da 8 block (~42ms @48k) — hap thu jitter pump
+//   nhung gioi han backlog: 64 block (~371ms) tao tre ~0.3-0.4s khi play/
+//   keyboard preview (audio moi phai cho ring cu chay het).
 // - Underrun: fade ve 0 thay vi click (hard silence).
 // - Resume sau silence: fade vao tu 0.
 // - Overrun: drop block cu nhat + crossfade 64 mau tai diem drop (het click).
@@ -8,7 +10,7 @@ class BridgeAudioSinkProcessor extends AudioWorkletProcessor {
   constructor() {
     super();
     this._ring = [];
-    this._MAX = 64;
+    this._MAX = 8;
     this._gain = 1.0;
     this._lastOutL = 0.0;
     this._lastOutR = 0.0;

app/static/js/services/unifiedMidiRouter.js

@@ -5,6 +5,8 @@
 (function () {
   var MELODIC_CHANNELS = [0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14]; // skip 9 (percussion); 15 reserved for Media Explorer preview
 
+  var _lastTimelineDbgTs = 0;
+
   var router = {
     bridgeConnected: false,
     onFallback: null,          // function(cmd, channel, pitch, velocity) — set by app.jsx
@@ -51,11 +53,29 @@
      * data2/data3 (A12): CC value / program / PB LSB|MSB — passed to bridge only.
      */
     pushEvent: function (opts) {
+      // V28: midi bất kỳ (keyboard/pad/timeline) → restore bridge gain đang
+      // giữ ~0.0001 sau stop (ding fix — V27 restore 800ms không đủ tail dài).
+      try { if (window.__restorePendingFadeSession) window.__restorePendingFadeSession(); } catch (e) {}
+      // V31: live note (ARM keyboard preview) — clear master FX outQueue backlog
+      // (idle block ~341ms) truoc khi note moi render; timeline note (live=false)
+      // KHONG clear — tranh drop audio dang phat.
+      if (opts.live && opts.cmd === 'NOTE_ON') { try { if (window.__clearMasterFxQueue) window.__clearMasterFxQueue(); } catch (e) {} }
       var cmd = opts.cmd, ch = opts.channel, pitch = opts.pitch;
       var vel = (opts.velocity === undefined ? 1.0 : opts.velocity);
       var sampleOffset = opts.sampleOffset || 0;
       if (typeof ch === 'string') ch = this.allocateChannel(ch, opts.percussion);
       if (ch === undefined || ch === null) ch = 0;
+      try {
+        // V36: midi_push log = 1 Tauri invoke sync (dbg_log -> disk I/O tren main
+        // thread Rust) moi event. Timeline phat ~380 event/s -> main thread nghet
+        // -> stall 110-170ms -> crackle. Chi log live (ARM preview), timeline
+        // gioi han 1/200ms.
+        var _nowMs = (window.performance && performance.now) ? performance.now() : Date.now();
+        if (window.__dbgLog && (opts.live || _nowMs - _lastTimelineDbgTs > 200)) {
+          if (!opts.live) _lastTimelineDbgTs = _nowMs;
+          window.__dbgLog('midi_push', 'cmd=' + cmd + ' ch=' + ch + ' live=' + (opts.live ? 1 : 0) + ' vel=' + Math.round((vel || 0) * 100) + (window.__dbgBridgeGain ? ' ' + window.__dbgBridgeGain() : '') + ' q=' + (window.__fxRtQueueLen ? window.__fxRtQueueLen() : 'n/a'));
+        }
+      } catch (e) {}
       if (this.isBridgeActive()) {
         window.NativeBridgeService.dispatchMidiEvent(cmd, ch, pitch, vel, sampleOffset, opts.data2, opts.data3, opts.live);
         return;