fix(bridge): closeGUI on channel worker thread — WM_DESTROY runs on main, view->removed() must run on the worker apartment or plugin corrupts and next attach hangs

native_bridge/src/main.cpp

@@ -55,25 +55,23 @@ static void sleep_ms(uint32_t ms) {
 // thread cua channel tao window) co the don map. USERDATA luu channel+1 (KHONG
 // luu con tro inst truc tiep: assign() thay inst moi moi lan load — con tro cu
 // bi huy → WM_DESTROY tren con tro dangling → crash/hang bridge).
+class ChannelWorker;  // fwd — WM_DESTROY posts closeGUI() to the channel worker
+static void post_close_gui(uint32_t ch, HWND hwnd);  // defined after ChannelWorker
 static InstrumentEngineManager* g_engine = nullptr;
 static std::mutex g_guiMutex;
 static std::map<uint32_t, void*> g_guiWindows;  // channel -> HWND (keep window alive)
 static std::map<HWND, uint32_t> g_hwndToCh;     // HWND -> channel (WM_DESTROY cleanup)
+static std::map<uint32_t, std::unique_ptr<ChannelWorker>>* g_workers = nullptr;
 
 static LRESULT CALLBACK VstWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
     if (uMsg == WM_DESTROY) {
-        INativeInstrument* instToClose = nullptr;
+        uint32_t ch = UINT32_MAX;
         {
             std::lock_guard<std::mutex> lock(g_guiMutex);
             auto it = g_hwndToCh.find(hwnd);
-            if (it != g_hwndToCh.end()) {
-                uint32_t ch = it->second;
-                g_hwndToCh.erase(it);
-                g_guiWindows.erase(ch);
-                if (g_engine) instToClose = g_engine->get(ch);
-            }
+            if (it != g_hwndToCh.end()) ch = it->second;
         }
-        if (instToClose) instToClose->closeGUI();
+        if (ch != UINT32_MAX) post_close_gui(ch, hwnd);
     }
     return DefWindowProcA(hwnd, uMsg, wParam, lParam);
 }
@@ -171,6 +169,32 @@ private:
     bool stop_ = false;
 };
 
+// closeGUI() MUST run on the channel worker thread (its COM STA apartment) —
+// the view was attached there. Calling view->removed() from the main thread
+// (WM_DESTROY handler) is a cross-apartment COM call that corrupts the plugin;
+// Nexus then hangs on the NEXT view->attached(). Erase the registry inside the
+// job so Option B (closing another editor before attach) waits for closeGUI to
+// actually finish.
+static void post_close_gui(uint32_t ch, HWND hwnd) {
+    ChannelWorker* w = nullptr;
+    if (g_workers) {
+        auto wit = g_workers->find(ch);
+        if (wit != g_workers->end()) w = wit->second.get();
+    }
+    if (w) {
+        w->post([ch, hwnd]() {
+            if (auto* i = g_engine->get(ch)) i->closeGUI();
+            std::lock_guard<std::mutex> lock(g_guiMutex);
+            g_hwndToCh.erase(hwnd);
+            g_guiWindows.erase(ch);
+        });
+    } else {
+        std::lock_guard<std::mutex> lock(g_guiMutex);
+        g_hwndToCh.erase(hwnd);
+        g_guiWindows.erase(ch);
+    }
+}
+
 int main(int argc, char* argv[]) {
     std::cout << "[NativeBridge] Starting DAW Host Bridge Engine..." << std::endl;
 
@@ -209,6 +233,7 @@ int main(int argc, char* argv[]) {
     // thread whose COM STA apartment stays alive for the channel's lifetime
     // (see ChannelWorker comment — a dead apartment hangs Nexus attached()).
     std::map<uint32_t, std::unique_ptr<ChannelWorker>> workers;
+    g_workers = &workers;
     // B9: native editor windows per channel — keep alive (HWND outlives the job).
     // Registry la global (g_guiWindows) — WM_DESTROY cleanup can tu VstWindowProc.
     // B8: sample rate from the DAW (Rust spawns us with SF_SAMPLE_RATE).