fix(api,ui): chan double-spawn GUI embed master chain - register bridge ngay sau Popen + inflight guard + frontend busy ref (crash 0xc0000005 2 instance Ozone)

app/api/v1/plugins.py

@@ -719,10 +719,17 @@ async def open_fx_gui(req: FxGuiRequest, current_user: dict = Depends(get_curren
     if not plugin_path:
         raise HTTPException(status_code=400, detail="Thiếu đường dẫn VST plugin.")
     # Tránh mở 2 GUI cùng plugin: nếu tiến trình bridge fx-gui cho plugin này
-    # đang chạy → trả started=False (frontend có thể focus window cũ).
+    # đang chạy (đã register sau Popen, kể cả khi còn đang chờ attach verdict)
+    # → trả started=False (frontend có thể focus window cũ).
     for proc in _FX_GUI_PROCESSES:
         if proc is not None and proc.poll() is None and getattr(proc, "_sf_plugin_path", None) == plugin_path:
             return {"success": True, "started": False, "already_running": True, "cmd": [], "embed_url": getattr(proc, "_sf_embed_url", None) or None}
+    # Request thứ 2 cho cùng plugin trong lúc spawn đầu ĐANG CHỜ verdict (có thể
+    # 20-70s cho Ozone-class) chưa thấy process nào register → phải chặn bằng
+    # inflight set, nếu không sẽ spawn bridge thứ 2 → 2 GUI instance Ozone cùng
+    # lúc → crash (0xc0000005 iZOzone11Core.dll) như bug đã gặp.
+    if req.embed and plugin_path in _FX_GUI_INFLIGHT:
+        return {"success": True, "started": False, "already_running": True, "cmd": [], "embed_url": None}
     job = {"path": plugin_path, "name": req.name or os.path.basename(plugin_path)}
     if req.shm:
         job["shm"] = req.shm
@@ -743,23 +750,25 @@ async def open_fx_gui(req: FxGuiRequest, current_user: dict = Depends(get_curren
             # in-process retry cannot recover from a crashed core DLL state).
             # Runs in a worker thread so the API event loop is not blocked for
             # the (long) load+attach+retry window.
-            proc, embed_url = await asyncio.to_thread(_spawn_fx_gui_embed, cmd)
-            if not embed_url:
-                _kill_fx_gui_proc(proc)
-                try:
-                    os.remove(job_path)
-                except Exception:
-                    pass
-                raise HTTPException(
-                    status_code=500,
-                    detail="Không mở được GUI embed cho plugin — bridge thất bại "
-                           "nhiều lần khi tải/mở editor (chi tiết trong log [fx-gui]).",
-                )
-            proc._sf_plugin_path = plugin_path
-            proc._sf_embed_url = embed_url
-            _register_fx_gui_process(proc)
-            return {"success": True, "started": True, "already_running": False,
-                    "embed_url": embed_url, "cmd": cmd}
+            _FX_GUI_INFLIGHT.add(plugin_path)
+            try:
+                proc, embed_url = await asyncio.to_thread(_spawn_fx_gui_embed, cmd, plugin_path)
+                if not embed_url:
+                    _kill_fx_gui_proc(proc)
+                    try:
+                        os.remove(job_path)
+                    except Exception:
+                        pass
+                    raise HTTPException(
+                        status_code=500,
+                        detail="Không mở được GUI embed cho plugin — bridge thất bại "
+                               "nhiều lần khi tải/mở editor (chi tiết trong log [fx-gui]).",
+                    )
+                proc._sf_embed_url = embed_url
+                return {"success": True, "started": True, "already_running": False,
+                        "embed_url": embed_url, "cmd": cmd}
+            finally:
+                _FX_GUI_INFLIGHT.discard(plugin_path)
         proc = subprocess.Popen(cmd, close_fds=os.name != "nt",
                                 env=dict(os.environ, SF_PARENT_PID=str(os.getpid())),
                                 creationflags=_fx_gui_creationflags())
@@ -797,11 +806,13 @@ async def close_fx_gui(req: FxGuiCloseRequest, current_user: dict = Depends(get_
 
 
 _FX_GUI_PROCESSES = []  # list[subprocess.Popen] — các bridge fx-gui do app spawn
+_FX_GUI_INFLIGHT = set()  # set[str] plugin_path — spawn embed đang chờ verdict
 
 def _register_fx_gui_process(proc):
     global _FX_GUI_PROCESSES
     _prune_fx_gui_processes()
-    _FX_GUI_PROCESSES.append(proc)
+    if proc not in _FX_GUI_PROCESSES:
+        _FX_GUI_PROCESSES.append(proc)
 
 def _prune_fx_gui_processes():
     global _FX_GUI_PROCESSES
@@ -829,7 +840,7 @@ def _kill_fx_gui_proc(proc):
         except Exception:
             proc.kill()
 
-def _spawn_fx_gui_embed(cmd):
+def _spawn_fx_gui_embed(cmd, plugin_path=None):
     """Spawn the fx-gui bridge and wait for the editor attach verdict.
 
     Process-level retry: an Ozone-class plugin can crash its GUI thread
@@ -851,6 +862,11 @@ def _spawn_fx_gui_embed(cmd):
             env=dict(os.environ, SF_PARENT_PID=str(os.getpid())),
             creationflags=_fx_gui_creationflags(),
         )
+        # Register NGAY sau Popen (trước vòng chờ verdict 20-70s): request thứ 2
+        # cho cùng plugin thấy process đang chạy → không spawn thêm instance GUI.
+        if plugin_path is not None:
+            proc._sf_plugin_path = plugin_path
+            _register_fx_gui_process(proc)
         holder = {"port": None, "opened": False}
 
         def _watch(pp, h):