M25: WS FX realtime sang Web Worker + MessageChannel worker->worklet (het underrun u1/u10 cold-start + stall main)

app/static/js/app.jsx

@@ -2029,6 +2029,48 @@ function fxRtWsOnMessage(ev) {
   for (let i = 0; i < half; i++) { l[i] = f[i * 2]; r[i] = f[i * 2 + 1]; }
   fxRt.node.port.postMessage({ type: 'out', l, r });
 }
+// M25: shim giu nguyen API WebSocket cu (readyState/send/onopen/onmessage/
+// onclose/onerror) nhung WS + binary deinterleave chay tren Web Worker; output
+// di THANG worker->worklet qua MessageChannel (directPort). ~20 call-site
+// fxRt.ws giu nguyen - khong sua. Main chi nhan text (latency/flush_done).
+function fxRtWsConnect(wsUrl, directPort) {
+  const _fireClose = (sh) => {
+    if (sh._closed) return;
+    sh._closed = true;
+    sh.readyState = 3; // CLOSED
+    try { if (sh._worker) sh._worker.terminate(); } catch (e) {}
+    if (sh.onclose) { try { sh.onclose(); } catch (e) {} }
+  };
+  const shim = {
+    readyState: 0,
+    onopen: null,
+    onmessage: null,
+    onclose: null,
+    onerror: null,
+    _worker: null,
+    _closed: false,
+    send(data) {
+      if (this._closed || !this._worker || this.readyState !== 1) return;
+      try {
+        if (typeof data === 'string') this._worker.postMessage({ kind: 'send', text: data });
+        // KHONG transfer list - fxRtChunks c.buffer reused (ws.send cu khong neuter)
+        else if (data instanceof ArrayBuffer) this._worker.postMessage({ kind: 'send', buf: data });
+      } catch (e) {}
+    },
+    close() { _fireClose(this); }
+  };
+  try { shim._worker = new Worker(`${API_BASE_URL}/static/js/fx-rt-worker.js?v=202608291749`); } catch (e) { throw e; } // giong ws constructor that -> caller catch cu giu nguyen
+  shim._worker.onmessage = (ev) => {
+    const d = ev.data;
+    if (!d || shim._closed) return;
+    if (d.kind === 'open') { shim.readyState = 1; if (shim.onopen) { try { shim.onopen(); } catch (e) {} } return; }
+    if (d.kind === 'close') { _fireClose(shim); return; }
+    if (d.kind === 'text') { if (shim.onmessage) { try { shim.onmessage({ data: d.text }); } catch (e) {} } }
+  };
+  shim._worker.onerror = () => _fireClose(shim);
+  try { shim._worker.postMessage({ kind: 'init', wsUrl, port: directPort || undefined }, directPort ? [directPort] : []); } catch (e) {}
+  return shim;
+}
 async function fxRtStart() {
   // V21: mọi play/chain-change gọi đây — hủy idle timer của lần stop trước
   // (không để session warm bị teardown giữa lúc đang chơi).
@@ -2177,9 +2219,14 @@ async function fxRtStart() {
       : u.host;
     const tok = localStorage.getItem('sonic_token') || '';
     const wsUrl = `${wsProto}${wsHost}${st.ws_url}${tok ? '?token=' + encodeURIComponent(tok) : ''}`;
-    const ws = new WebSocket(wsUrl);
+    // M25: WS chay tren Web Worker - binary output/input di THANG
+    // worker<->worklet qua MessageChannel (directPort). Main-thread stall (rAF/
+    // React/render luc cold start) khong con tre frame -> het underrun u1/u10.
+    // Text (latency/flush_done) van forward main nhu cu.
+    const _chan = new MessageChannel();
+    try { fxRt.node.port.postMessage({ type: '__direct', port: _chan.port2 }, [_chan.port2]); } catch (e) {}
+    const ws = fxRtWsConnect(wsUrl, _chan.port1);
     fxRt.ws = ws;
-    ws.binaryType = 'arraybuffer';
     ws.onopen = () => {
       if (token !== fxRt.startToken) { try { ws.close(); } catch (e) {} fxRt.starting = false; return; }
       fxRt.active = true;
@@ -2468,9 +2515,11 @@ async function fxRtWarmEnsure(chain) {
     : u.host;
   const tok = localStorage.getItem('sonic_token') || '';
   const wsUrl = `${wsProto}${wsHost}${st.ws_url}${tok ? '?token=' + encodeURIComponent(tok) : ''}`;
+  // M25: WS chay tren Web Worker - warm chua co node (khong directPort);
+  // worker van giu WS, binary drop trong worker nhu cu main drop (!fxRt.node).
   let ws;
   try {
-    ws = new WebSocket(wsUrl);
+    ws = fxRtWsConnect(wsUrl, null);
   } catch (e) {
     try { window.SonicAPI.fxRealtimeStop({ session_id: st.session_id }).catch(() => {}); } catch (e2) {}
     fxRt.sessionId = null;
@@ -2479,7 +2528,6 @@ async function fxRtWarmEnsure(chain) {
     return null;
   }
   fxRt.ws = ws;
-  ws.binaryType = 'arraybuffer';
   ws.onopen = () => {
     if (token !== fxRt.startToken) {
       // Bị thay bằng session mới hơn — dọn session mình vừa tạo (nếu vẫn là