fix: support headless MuJoCo image capture during rollout

tests/test_eval_vla_headless.py

@@ -129,6 +129,49 @@ class EvalVLAHeadlessTest(unittest.TestCase):
             cam_view="angle",
         )
 
+    def test_headless_sync_camera_capture_populates_images_without_gui_calls(self):
+        env = DualDianaMed.__new__(DualDianaMed)
+        env.mj_model = object()
+        env.mj_data = object()
+        env.exit_flag = False
+        env.is_render = False
+        env.cam = 'angle'
+        env.r_vis = None
+        env.l_vis = None
+        env.top = None
+        env.angle = None
+        env.front = None
+        env._offscreen_renderer = None
+
+        with mock.patch(
+            'roboimi.envs.double_base.mj.Renderer',
+            side_effect=lambda *args, **kwargs: _FakeRenderer(env),
+        ) as renderer_cls, mock.patch('roboimi.envs.double_base.cv2.namedWindow') as named_window, mock.patch(
+            'roboimi.envs.double_base.cv2.imshow'
+        ) as imshow, mock.patch('roboimi.envs.double_base.cv2.waitKey') as wait_key:
+            env._update_camera_images_sync()
+
+        renderer_cls.assert_called_once()
+        named_window.assert_not_called()
+        imshow.assert_not_called()
+        wait_key.assert_not_called()
+        self.assertIsNotNone(env.r_vis)
+        self.assertIsNotNone(env.l_vis)
+        self.assertIsNotNone(env.top)
+        self.assertIsNotNone(env.angle)
+        self.assertIsNotNone(env.front)
+
+    def test_cam_start_skips_background_thread_when_headless(self):
+        env = DualDianaMed.__new__(DualDianaMed)
+        env.is_render = False
+        env.cam_thread = None
+
+        with mock.patch('roboimi.envs.double_base.threading.Thread') as thread_cls:
+            env.cam_start()
+
+        thread_cls.assert_not_called()
+        self.assertIsNone(env.cam_thread)
+
     def test_camera_viewer_headless_updates_images_without_gui_calls(self):
         env = DualDianaMed.__new__(DualDianaMed)
         env.mj_model = object()