fix(rl): record pre-step observation so (obs, action, next.reward) align in gym_manipulator dataset

src/lerobot/rl/gym_manipulator.py

@@ -698,6 +698,12 @@ def control_loop(
             if use_gripper:
                 neutral_action = torch.cat([neutral_action, torch.tensor([1.0])])  # Gripper stay
 
+            observation = {
+                k: v.squeeze(0).cpu()
+                for k, v in transition[TransitionKey.OBSERVATION].items()
+                if isinstance(v, torch.Tensor)
+            }
+
             transition = step_env_and_process_transition(
                 env=env,
                 transition=transition,
@@ -709,16 +715,11 @@ def control_loop(
             truncated = transition.get(TransitionKey.TRUNCATED, False)
 
             if cfg.mode == "record":
-                observations = {
-                    k: v.squeeze(0).cpu()
-                    for k, v in transition[TransitionKey.OBSERVATION].items()
-                    if isinstance(v, torch.Tensor)
-                }
                 action_to_record = transition[TransitionKey.COMPLEMENTARY_DATA].get(
                     "teleop_action", transition[TransitionKey.ACTION]
                 )
                 frame = {
-                    **observations,
+                    **observation,
                     ACTION: action_to_record.cpu(),
                     REWARD: np.array([transition[TransitionKey.REWARD]], dtype=np.float32),
                     DONE: np.array([terminated or truncated], dtype=bool),