Allow Groot fake RTC chunk prefetch

src/lerobot/policies/groot/modeling_groot.py

@@ -342,10 +342,14 @@ class GrootPolicy(PreTrainedPolicy):
         return loss, loss_dict
 
     @torch.no_grad()
-    def predict_action_chunk(self, batch: dict[str, Tensor]) -> Tensor:
+    def predict_action_chunk(self, batch: dict[str, Tensor], **_: object) -> Tensor:
         """Predict a chunk of actions for inference by delegating to Isaac-GR00T.
 
         Returns a tensor of shape (B, n_action_steps, action_dim).
+
+        Groot does not currently implement LeRobot's RTC guidance contract. Accept
+        and ignore action-selection kwargs so the RTC engine can still use Groot as
+        an async chunk producer.
         """
         self.eval()
 

tests/policies/groot/test_groot_n1_7.py

@@ -14,6 +14,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import inspect
 import json
 import sys
 from types import SimpleNamespace
@@ -419,6 +420,13 @@ def test_groot_n1_7_can_be_selected_from_policy_config_factory_without_external_
     assert "gr00t" not in sys.modules
 
 
+def test_groot_predict_action_chunk_accepts_rtc_kwargs():
+    signature = inspect.signature(GrootPolicy.predict_action_chunk)
+
+    assert any(parameter.kind is inspect.Parameter.VAR_KEYWORD for parameter in signature.parameters.values())
+    signature.bind(object(), {}, inference_delay=2, prev_chunk_left_over=None)
+
+
 def test_groot_from_pretrained_rejects_mismatched_caller_config(tmp_path):
     model_path = tmp_path / "GR00T-N1.7-local"
     model_path.mkdir()