fix(v9): 5 bugs — GUI deferred until VST loaded (no white window), fixed retry 8x500ms, VST3 folder resolve for auto-load, sustain-CC64 dropped after STOP, taskkill process tree on exit, Synth+GUI same row in TCP

native_bridge/src/main.cpp

@@ -306,6 +306,11 @@ int main(int argc, char* argv[]) {
                 inst->noteOff(evt.channel, evt.pitch, 0);
                 break;
             case 0xB: // CC: controller number in pitch, value in data2
+                // V9 bug 4: sau STOP, drop sustain-down (CC64>0) — JS co the
+                // gui CC64 xuong sau STOP (note-on/CC timer tre); VSTi giu
+                // note khi pedal down -> am treo loop. CC64=0 (sustain-up)
+                // van cho qua.
+                if (transportStopped && evt.pitch == 64 && evt.data2 > 0) return;
                 inst->controlChange(evt.channel, evt.pitch, evt.data2);
                 break;
             case 0xC: // program change: program in data2
@@ -418,6 +423,17 @@ int main(int argc, char* argv[]) {
             } else if (c.type == 4) { // OPEN_GUI (A7): arg1 = parent HWND (0 → bridge tự tạo native window), arg2 = plugin id
                 uint32_t guiCh = c.channel;
                 if (guiCh >= 16) guiCh = 0;
+                // V9 bug 3/6/7: gate tren MAIN thread TRUOC khi tao window —
+                // instrument load ASYNC (worker thread); OPEN_GUI som -> attach
+                // job fail -> cua so trang van con song. Chua load xong =>
+                // defer: KHONG tao window, KHONG post job. JS retry
+                // openNativeGUI 8x500ms; khi assign xong nhay lai day, tao
+                // window 1 lan va attach OK.
+                if (!instruments.get(guiCh)) {
+                    std::cerr << "[NativeBridge] GUI deferred ch=" << guiCh
+                              << " plugin=" << c.arg2 << " (no instrument yet)" << std::endl;
+                    continue;
+                }
                 if (!workers[guiCh]) workers[guiCh] = std::make_unique<ChannelWorker>();
                 void* hwnd = (void*)(uintptr_t)c.arg1;
 #ifdef _WIN32