V45.39: fix SERVER OFFLINE lau + UI load cham - engine ghi port file (engine_port.txt), UI bootstrap doc port engine cua chinh no (get_engine_port) + timeout/retry 60s, health poll self-heal reload, khong taskkill /IM daw_engine (giet engine instance khac), /api/v1/plugins/available chay scan trong threadpool (khong chan event loop -> /health het timeout)

app/api/v1/plugins.py

@@ -194,6 +194,14 @@ def get_scanner():
 
 @router.get("/available")
 async def list_plugins(current_user: dict = Depends(get_current_user)):
+    # Scan VST/SF chạy subprocess đồng bộ (fx_vst_bridge --scan, timeout 300s/
+    # dir; Ozone treo tới 30s/module) — chạy trực tiếp trên event loop sẽ chặn
+    # /health và mọi request khác → UI báo SERVER: OFFLINE suốt thời gian scan.
+    # Chạy trong threadpool để event loop luôn phản hồi.
+    return await asyncio.to_thread(_list_plugins_impl)
+
+
+def _list_plugins_impl():
     d = _effective_dirs()
     pm = PluginManager(vst_dir=d["vst_dir"], sf_dir=d["soundfont_dir"], upload_sf_dir=UPLOAD_SF_DIR, extra_vst_dirs=d["plugin_dirs"], user_dirs_override=d.get("plugin_dirs_user_set", False))
     avail = pm.list_available()

app/static/js/app.jsx

@@ -23741,15 +23741,28 @@ const App = () => {
     return () => observer.disconnect();
   }, [timelineWrapperNode]);
   useEffect(() => {
-    let cancelled = false, busy = false, iv = null;
+    let cancelled = false, busy = false, iv = null, offlineCount = 0;
     const check = () => {
       if (busy || cancelled) return;
       busy = true;
       const ctl = new AbortController();
       const t = setTimeout(() => ctl.abort(), 3000);
       fetch(API_BASE_URL, { signal: ctl.signal })
-        .then(r => { if (!cancelled) setServerStatus(r.ok ? 'connected' : 'error'); })
-        .catch(() => { if (!cancelled) setServerStatus('offline'); })
+        .then(r => { if (!cancelled) { setServerStatus(r.ok ? 'connected' : 'error'); offlineCount = 0; } })
+        .catch(() => {
+          if (!cancelled) {
+            setServerStatus('offline');
+            // Self-heal: engine chết/mất kết nối liên tục (~9s) → reload trang
+            // để bootstrap chạy lại: ưu tiên port engine của chính app
+            // (engine_port.txt) + fallback quét 8000-8010. Trước đây kẹt
+            // OFFLINE vĩnh viễn khi engine bị instance khác giết port.
+            offlineCount++;
+            if (offlineCount >= 3) {
+              offlineCount = 0;
+              try { window.location.reload(); } catch (e) {}
+            }
+          }
+        })
         .finally(() => { busy = false; clearTimeout(t); });
     };
     check();

app/templates/index.html

@@ -51,7 +51,7 @@
     <script src="/static/js/services/promptTemplateManager.js?v=202608290945"></script>
     <script src="/static/js/services/undoRedoEngine.js?v=202608290945"></script>
     <script src="/static/js/services/chordTheory.js?v=202608290945"></script>
-    <script src="/static/js/app.precompiled.js?v=202608311858" defer></script>
+    <script src="/static/js/app.precompiled.js?v=202609011700" defer></script>
     <link rel="stylesheet" href="/static/css/styles.css?v=202608290945">
     <style>
         :root {