diff --git a/src/lab/QuestCubeLab.tsx b/src/lab/QuestCubeLab.tsx
index da535f7..5eb5bdf 100644
--- a/src/lab/QuestCubeLab.tsx
+++ b/src/lab/QuestCubeLab.tsx
@@ -314,59 +314,63 @@ const PhysicsScene = ({
 // ===================================================================
 // SCENE WRAPPER — junta o Canvas + R3F
 // ===================================================================
-const SceneContent = ({ locked, resetSignal }: { locked: boolean; resetSignal: number }) => (
-  <>
-    {/* Em modo AR Passthrough, NÃO pinta cor de fundo — ela veda o passthrough */}
-    {/* Em modo desktop (fora do XR), pinta fundo escuro pra não ficar transparente estranho */}
-    <ARBackground />
-
-    <ambientLight intensity={0.6} />
-    <directionalLight
-      position={[5, 5, 5]}
-      intensity={1.2}
-      castShadow
-      shadow-mapSize={[1024, 1024]}
-    />
-
-    {/* Grid estilo HLA — funciona em ambos os modos */}
-    <Grid
-      position={[0, 0.001, 0]}
-      args={[20, 20]}
-      cellSize={0.25}
-      cellThickness={0.5}
-      cellColor="#334155"
-      sectionSize={1}
-      sectionThickness={1}
-      sectionColor="#64748b"
-      fadeDistance={12}
-      fadeStrength={1.5}
-      infiniteGrid
-    />
-
-    <Suspense fallback={null}>
-      <Environment preset="warehouse" />
-    </Suspense>
-
-    <PhysicsScene locked={locked} resetSignal={resetSignal} />
-
-    {/* Controles pra visualização fora do XR (mouse) */}
-    <OrbitControls
-      makeDefault
-      target={[0, 0.5, 0]}
-      enablePan={true}
-      minDistance={1}
-      maxDistance={10}
-    />
-  </>
-);
-
-// ===================================================================
-// FUNDO DINÂMICO — VR imersivo fica preto; AR Passthrough fica transparente
-// ===================================================================
-const ARBackground = () => {
+const SceneContent = ({ locked, resetSignal }: { locked: boolean; resetSignal: number }) => {
+  // Detecta modo AR para ajustar iluminação e fundo
   const session = useXR((s) => s.session);
-  const isAR = session && "environmentBlendMode" in session && (session as any).environmentBlendMode === "additive";
-  if (isAR) return null; // AR = transparente (mostra passthrough do Quest 3)
+  const isAR = !!(session && (session as any).environmentBlendMode === "additive");
+
+  return (
+    <>
+      <ARBackground isAR={isAR} />
+
+      <ambientLight intensity={isAR ? 1.2 : 0.6} />
+      <directionalLight
+        position={[5, 5, 5]}
+        intensity={isAR ? 1.5 : 1.2}
+        castShadow
+        shadow-mapSize={[1024, 1024]}
+      />
+
+      {/* Grid estilo HLA — funciona em ambos os modos */}
+      <Grid
+        position={[0, 0.001, 0]}
+        args={[20, 20]}
+        cellSize={0.25}
+        cellThickness={0.5}
+        cellColor="#334155"
+        sectionSize={1}
+        sectionThickness={1}
+        sectionColor="#64748b"
+        fadeDistance={12}
+        fadeStrength={1.5}
+        infiniteGrid
+      />
+
+      <Suspense fallback={null}>
+        <Environment preset="warehouse" />
+      </Suspense>
+
+      <PhysicsScene locked={locked} resetSignal={resetSignal} />
+
+      <OrbitControls
+        makeDefault
+        target={[0, 0.5, 0]}
+        enablePan={true}
+        minDistance={1}
+        maxDistance={10}
+      />
+    </>
+  );
+};
+
+// ===================================================================
+// FUNDO DINÂMICO — Recebe prop isAR para evitar montagem/desmontagem
+// ===================================================================
+const ARBackground = ({ isAR }: { isAR: boolean }) => {
+  // Em AR Passthrough: nada (canal alpha fica livre pra passthrough)
+  if (isAR) return null;
+
+  // Fora de AR (modo desktop ou VR): fundo preto
   return (
     <>
       <color attach="background" args={["#0a0a0a"]} />