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/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;