Enable <StrictMode> + make App.tsx renderer init idempotent

App.tsx's prepare() useEffect ran four .init() calls
(SessionDataManager, RoomSessionManager, RoomEngine, Communication)
without any guard, plus an immediate heartbeat ping and a legacy
authentication track. Under StrictMode dev double-invoke, those
fire twice — risking duplicate session/communication state.

- Gate the four .init() chain behind gameInitPromiseRef: both the
  first and the simulated second invocation await the same promise.
- Gate the legacy track + immediate heartbeat behind bootstrapDoneRef.
- Heartbeat and remember-rotate intervals were already idempotent
  (clearInterval before setInterval); ticker registration was already
  guarded by tickersStartedRef; renderer/warmup were already gated by
  rendererPromiseRef/warmupPromiseRef. No change needed there.

Wrap <App /> in <StrictMode> in src/index.tsx now that the renderer
init path is double-invoke safe.

https://claude.ai/code/session_01GrR87LAqnAEyKG2ZbmQt5Q

src/App.tsx

@@ -74,6 +74,8 @@ export const App: FC<{}> = props =>
     const [ prepareTrigger, setPrepareTrigger ] = useState(0);
     const warmupPromiseRef = useRef<Promise<void>>(null);
     const rendererPromiseRef = useRef<Promise<any>>(null);
+    const gameInitPromiseRef = useRef<Promise<void> | null>(null);
+    const bootstrapDoneRef = useRef(false);
     const tickersStartedRef = useRef(false);
     const heartbeatIntervalRef = useRef<number>(null);
     const rememberRotateIntervalRef = useRef<number>(null);
@@ -385,14 +387,26 @@ export const App: FC<{}> = props =>
                 const renderer = await startRenderer(width, height);
 
                 await startWarmup(width, height);
-                await GetSessionDataManager().init();
-                await GetRoomSessionManager().init();
-                await GetRoomEngine().init();
-                await GetCommunication().init();
 
-                if(LegacyExternalInterface.available) LegacyExternalInterface.call('legacyTrack', 'authentication', 'authok', []);
+                if(!gameInitPromiseRef.current)
+                {
+                    gameInitPromiseRef.current = (async () =>
+                    {
+                        await GetSessionDataManager().init();
+                        await GetRoomSessionManager().init();
+                        await GetRoomEngine().init();
+                        await GetCommunication().init();
+                    })();
+                }
 
-                HabboWebTools.sendHeartBeat();
+                await gameInitPromiseRef.current;
+
+                if(!bootstrapDoneRef.current)
+                {
+                    bootstrapDoneRef.current = true;
+                    if(LegacyExternalInterface.available) LegacyExternalInterface.call('legacyTrack', 'authentication', 'authok', []);
+                    HabboWebTools.sendHeartBeat();
+                }
 
                 if(heartbeatIntervalRef.current !== null) window.clearInterval(heartbeatIntervalRef.current);
                 heartbeatIntervalRef.current = window.setInterval(() => HabboWebTools.sendHeartBeat(), 10000);

src/index.tsx

@@ -1,4 +1,4 @@
-import { Suspense } from 'react';
+import { StrictMode, Suspense } from 'react';
 import { createRoot } from 'react-dom/client';
 import { ErrorBoundary } from 'react-error-boundary';
 import { App } from './App';
@@ -44,15 +44,17 @@ import './css/toolbar/ToolBar.css';
 import './css/widgets/FurnitureWidgets.css';
 
 createRoot(document.getElementById('root')).render(
-    <ErrorBoundary
-        fallbackRender={ ({ error }) => (
-            <LoadingView
-                isError={ true }
-                message={ `Something went wrong.\n${ (error as Error)?.message ?? 'Unknown error' }` }
-                homeUrl={ window.location.origin + '/' } />
-        ) }>
-        <Suspense fallback={ <LoadingView message="Loading…" /> }>
-            <App />
-        </Suspense>
-    </ErrorBoundary>
+    <StrictMode>
+        <ErrorBoundary
+            fallbackRender={ ({ error }) => (
+                <LoadingView
+                    isError={ true }
+                    message={ `Something went wrong.\n${ (error as Error)?.message ?? 'Unknown error' }` }
+                    homeUrl={ window.location.origin + '/' } />
+            ) }>
+            <Suspense fallback={ <LoadingView message="Loading…" /> }>
+                <App />
+            </Suspense>
+        </ErrorBoundary>
+    </StrictMode>
 );