Merge branch 'main' into feature/add-multitask-dit

tests/policies/pi0_pi05/test_pi05_rtc.py

@@ -0,0 +1,336 @@
+#!/usr/bin/env python
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Test PI0.5 policy with Real-Time Chunking (RTC) enabled during inference."""
+
+import os
+
+import pytest
+import torch
+
+# Skip this entire module in CI
+pytestmark = pytest.mark.skipif(
+    os.environ.get("CI") == "true" or os.environ.get("GITHUB_ACTIONS") == "true",
+    reason="This test requires local OpenPI installation and is not meant for CI",
+)
+
+from lerobot.configs.types import FeatureType, PolicyFeature, RTCAttentionSchedule  # noqa: E402
+from lerobot.policies.pi05 import PI05Config, PI05Policy, make_pi05_pre_post_processors  # noqa: E402
+from lerobot.policies.rtc.configuration_rtc import RTCConfig  # noqa: E402
+from lerobot.utils.random_utils import set_seed  # noqa: E402
+from tests.utils import require_cuda  # noqa: E402
+
+
+@require_cuda
+def test_pi05_rtc_initialization():
+    """Test PI0.5 policy can initialize RTC processor."""
+    set_seed(42)
+
+    config = PI05Config(max_action_dim=7, max_state_dim=14, dtype="float32")
+
+    # Add RTC config
+    config.rtc_config = RTCConfig(
+        enabled=True,
+        execution_horizon=10,
+        max_guidance_weight=5.0,
+        prefix_attention_schedule=RTCAttentionSchedule.EXP,
+        debug=False,
+    )
+
+    config.input_features = {
+        "observation.state": PolicyFeature(type=FeatureType.STATE, shape=(14,)),
+        "observation.images.base_0_rgb": PolicyFeature(type=FeatureType.VISUAL, shape=(3, 224, 224)),
+    }
+    config.output_features = {
+        "action": PolicyFeature(type=FeatureType.ACTION, shape=(7,)),
+    }
+
+    # Instantiate policy
+    policy = PI05Policy(config)
+
+    # Verify RTC processor is initialized
+    assert hasattr(policy, "rtc_processor")
+    assert policy.rtc_processor is not None
+    assert policy.rtc_processor.rtc_config.enabled is True
+
+    print("✓ PI0.5 RTC initialization: Test passed")
+
+
+@require_cuda
+def test_pi05_rtc_initialization_without_rtc_config():
+    """Test PI0.5 policy can initialize without RTC config."""
+    set_seed(42)
+
+    config = PI05Config(max_action_dim=7, max_state_dim=14, dtype="float32")
+
+    # Instantiate policy
+    policy = PI05Policy(config)
+
+    # Verify RTC processor is not initialized
+    assert hasattr(policy, "rtc_processor")
+    assert policy.rtc_processor is None
+    assert policy.model.rtc_processor is None
+    assert policy._rtc_enabled() is False
+
+    print("✓ PI0.5 RTC initialization without RTC config: Test passed")
+
+
+@require_cuda
+def test_pi05_rtc_inference_with_prev_chunk():
+    """Test PI0.5 policy inference with RTC and previous chunk."""
+    set_seed(42)
+
+    config = PI05Config(max_action_dim=7, max_state_dim=14, chunk_size=50, dtype="float32")
+
+    # Add RTC config
+    config.rtc_config = RTCConfig(
+        enabled=True,
+        execution_horizon=10,
+        max_guidance_weight=5.0,
+        prefix_attention_schedule=RTCAttentionSchedule.EXP,
+        debug=False,
+    )
+
+    config.input_features = {
+        "observation.state": PolicyFeature(type=FeatureType.STATE, shape=(14,)),
+        "observation.images.base_0_rgb": PolicyFeature(type=FeatureType.VISUAL, shape=(3, 224, 224)),
+    }
+    config.output_features = {
+        "action": PolicyFeature(type=FeatureType.ACTION, shape=(7,)),
+    }
+
+    # Create dataset stats (PI0.5 uses QUANTILES normalization)
+    dataset_stats = {
+        "observation.state": {
+            "mean": torch.zeros(14),
+            "std": torch.ones(14),
+            "q01": -torch.ones(14),
+            "q99": torch.ones(14),
+        },
+        "action": {
+            "mean": torch.zeros(7),
+            "std": torch.ones(7),
+            "q01": -torch.ones(7),
+            "q99": torch.ones(7),
+        },
+        "observation.images.base_0_rgb": {"mean": torch.zeros(3, 224, 224), "std": torch.ones(3, 224, 224)},
+    }
+
+    # Instantiate policy and preprocessor
+    policy = PI05Policy(config)
+    policy.eval()
+    preprocessor, _ = make_pi05_pre_post_processors(config=config, dataset_stats=dataset_stats)
+
+    device = config.device
+
+    # Create dummy batch
+    batch = {
+        "observation.state": torch.randn(1, 14, dtype=torch.float32, device=device),
+        "observation.images.base_0_rgb": torch.rand(1, 3, 224, 224, dtype=torch.float32, device=device),
+        "task": ["Pick up the object"],
+    }
+    batch = preprocessor(batch)
+
+    # Create previous chunk
+    prev_chunk = torch.randn(1, 25, 7, dtype=torch.float32, device=device)
+
+    with torch.no_grad():
+        # Use same noise for fair comparison
+        noise = policy.model.sample_noise((1, config.chunk_size, 7), device)
+
+        # Test with RTC and previous chunk
+        actions_with_rtc = policy.predict_action_chunk(
+            batch,
+            noise=noise.clone(),
+            prev_chunk_left_over=prev_chunk,
+            inference_delay=4,
+            execution_horizon=10,
+        )
+
+        # Test without RTC for comparison
+        policy.config.rtc_config.enabled = False
+        actions_without_rtc = policy.predict_action_chunk(batch, noise=noise.clone())
+        policy.config.rtc_config.enabled = True
+
+    # Verify shapes
+    assert actions_with_rtc.shape == (1, config.chunk_size, 7)
+    assert actions_without_rtc.shape == (1, config.chunk_size, 7)
+
+    # With previous chunk, actions should be different (RTC guidance applied)
+    assert not torch.allclose(actions_with_rtc, actions_without_rtc, rtol=1e-3)
+
+    print("✓ PI0.5 RTC inference with prev_chunk: Test passed")
+
+
+@require_cuda
+def test_pi05_rtc_inference_without_prev_chunk():
+    """Test PI0.5 policy inference with RTC but no previous chunk (RTC should have no effect)."""
+    set_seed(42)
+
+    config = PI05Config(max_action_dim=7, max_state_dim=14, chunk_size=50, dtype="float32")
+
+    # Add RTC config
+    config.rtc_config = RTCConfig(
+        enabled=True,
+        execution_horizon=10,
+        max_guidance_weight=5.0,
+        prefix_attention_schedule=RTCAttentionSchedule.EXP,
+        debug=False,
+    )
+
+    config.input_features = {
+        "observation.state": PolicyFeature(type=FeatureType.STATE, shape=(14,)),
+        "observation.images.base_0_rgb": PolicyFeature(type=FeatureType.VISUAL, shape=(3, 224, 224)),
+    }
+    config.output_features = {
+        "action": PolicyFeature(type=FeatureType.ACTION, shape=(7,)),
+    }
+
+    # Create dataset stats (PI0.5 uses QUANTILES normalization)
+    dataset_stats = {
+        "observation.state": {
+            "mean": torch.zeros(14),
+            "std": torch.ones(14),
+            "q01": -torch.ones(14),
+            "q99": torch.ones(14),
+        },
+        "action": {
+            "mean": torch.zeros(7),
+            "std": torch.ones(7),
+            "q01": -torch.ones(7),
+            "q99": torch.ones(7),
+        },
+        "observation.images.base_0_rgb": {"mean": torch.zeros(3, 224, 224), "std": torch.ones(3, 224, 224)},
+    }
+
+    # Instantiate policy and preprocessor
+    policy = PI05Policy(config)
+    policy.eval()
+    preprocessor, _ = make_pi05_pre_post_processors(config=config, dataset_stats=dataset_stats)
+
+    device = config.device
+
+    # Create dummy batch
+    batch = {
+        "observation.state": torch.randn(1, 14, dtype=torch.float32, device=device),
+        "observation.images.base_0_rgb": torch.rand(1, 3, 224, 224, dtype=torch.float32, device=device),
+        "task": ["Pick up the object"],
+    }
+    batch = preprocessor(batch)
+
+    with torch.no_grad():
+        # Use same noise for fair comparison
+        noise = policy.model.sample_noise((1, config.chunk_size, 7), device)
+
+        # Test with RTC enabled but no previous chunk
+        actions_with_rtc_no_prev = policy.predict_action_chunk(
+            batch,
+            noise=noise.clone(),
+            prev_chunk_left_over=None,
+        )
+
+        # Test without RTC
+        policy.config.rtc_config.enabled = False
+        actions_without_rtc = policy.predict_action_chunk(batch, noise=noise.clone())
+        policy.config.rtc_config.enabled = True
+
+    # Without previous chunk, RTC should have no effect
+    assert torch.allclose(actions_with_rtc_no_prev, actions_without_rtc, rtol=1e-5)
+
+    print("✓ PI0.5 RTC inference without prev_chunk: Test passed")
+
+
+@require_cuda
+def test_pi05_rtc_validation_rules():
+    """Test PI0.5 policy with RTC follows all three validation rules."""
+    set_seed(42)
+
+    config = PI05Config(max_action_dim=7, max_state_dim=14, chunk_size=50, dtype="float32")
+
+    # Add RTC config
+    config.rtc_config = RTCConfig(
+        enabled=True,
+        execution_horizon=10,
+        max_guidance_weight=5.0,
+        prefix_attention_schedule=RTCAttentionSchedule.EXP,
+        debug=False,
+    )
+
+    config.input_features = {
+        "observation.state": PolicyFeature(type=FeatureType.STATE, shape=(14,)),
+        "observation.images.base_0_rgb": PolicyFeature(type=FeatureType.VISUAL, shape=(3, 224, 224)),
+    }
+    config.output_features = {
+        "action": PolicyFeature(type=FeatureType.ACTION, shape=(7,)),
+    }
+
+    # Create dataset stats (PI0.5 uses QUANTILES normalization)
+    dataset_stats = {
+        "observation.state": {
+            "mean": torch.zeros(14),
+            "std": torch.ones(14),
+            "q01": -torch.ones(14),
+            "q99": torch.ones(14),
+        },
+        "action": {
+            "mean": torch.zeros(7),
+            "std": torch.ones(7),
+            "q01": -torch.ones(7),
+            "q99": torch.ones(7),
+        },
+        "observation.images.base_0_rgb": {"mean": torch.zeros(3, 224, 224), "std": torch.ones(3, 224, 224)},
+    }
+
+    # Instantiate policy and preprocessor
+    policy = PI05Policy(config)
+    policy.eval()
+    preprocessor, _ = make_pi05_pre_post_processors(config=config, dataset_stats=dataset_stats)
+
+    device = config.device
+
+    # Create dummy batch
+    batch = {
+        "observation.state": torch.randn(1, 14, dtype=torch.float32, device=device),
+        "observation.images.base_0_rgb": torch.rand(1, 3, 224, 224, dtype=torch.float32, device=device),
+        "task": ["Pick up the object"],
+    }
+    batch = preprocessor(batch)
+
+    # Create previous chunk
+    prev_chunk = torch.randn(1, 25, 7, dtype=torch.float32, device=device)
+
+    inference_delay = 4
+    execution_horizon = 10
+
+    with torch.no_grad():
+        # Use same noise for fair comparison
+        noise = policy.model.sample_noise((1, config.chunk_size, 7), device)
+
+        # Test with RTC
+        actions_with_rtc = policy.predict_action_chunk(
+            batch,
+            noise=noise.clone(),
+            prev_chunk_left_over=prev_chunk,
+            inference_delay=inference_delay,
+            execution_horizon=execution_horizon,
+        )
+
+        # Test without RTC
+        policy.config.rtc_config.enabled = False
+        actions_without_rtc = policy.predict_action_chunk(batch, noise=noise.clone())
+        policy.config.rtc_config.enabled = True
+
+    assert not torch.allclose(actions_with_rtc, actions_without_rtc, rtol=1e-3)

tests/policies/pi0_pi05/test_pi0_rtc.py

@@ -0,0 +1,378 @@
+#!/usr/bin/env python
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Test PI0 policy with Real-Time Chunking (RTC) enabled during inference."""
+
+import os
+
+import pytest
+import torch
+
+# Skip this entire module in CI
+pytestmark = pytest.mark.skipif(
+    os.environ.get("CI") == "true" or os.environ.get("GITHUB_ACTIONS") == "true",
+    reason="This test requires local OpenPI installation and is not meant for CI",
+)
+
+from lerobot.configs.types import FeatureType, PolicyFeature, RTCAttentionSchedule  # noqa: E402
+from lerobot.policies.pi0 import PI0Config, PI0Policy, make_pi0_pre_post_processors  # noqa: E402
+from lerobot.policies.rtc.configuration_rtc import RTCConfig  # noqa: E402
+from lerobot.utils.random_utils import set_seed  # noqa: E402
+from tests.utils import require_cuda  # noqa: E402
+
+
+@require_cuda
+def test_pi0_rtc_initialization():
+    """Test PI0 policy can initialize RTC processor."""
+    set_seed(42)
+
+    config = PI0Config(max_action_dim=7, max_state_dim=14, dtype="float32")
+
+    # Add RTC config
+    config.rtc_config = RTCConfig(
+        enabled=True,
+        execution_horizon=10,
+        max_guidance_weight=5.0,
+        prefix_attention_schedule=RTCAttentionSchedule.EXP,
+        debug=False,
+    )
+
+    config.input_features = {
+        "observation.state": PolicyFeature(type=FeatureType.STATE, shape=(14,)),
+        "observation.images.base_0_rgb": PolicyFeature(type=FeatureType.VISUAL, shape=(3, 224, 224)),
+    }
+    config.output_features = {
+        "action": PolicyFeature(type=FeatureType.ACTION, shape=(7,)),
+    }
+
+    # Instantiate policy
+    policy = PI0Policy(config)
+
+    # Verify RTC processor is initialized
+    assert hasattr(policy, "rtc_processor")
+    assert policy.rtc_processor is not None
+    assert policy.rtc_processor.rtc_config.enabled is True
+
+    print("✓ PI0 RTC initialization: Test passed")
+
+
+@require_cuda
+def test_pi0_rtc_initialization_without_rtc_config():
+    """Test PI0 policy can initialize without RTC config."""
+    set_seed(42)
+
+    config = PI0Config(max_action_dim=7, max_state_dim=14, dtype="float32")
+
+    # Instantiate policy
+    policy = PI0Policy(config)
+
+    # Verify RTC processor is not initialized
+    assert hasattr(policy, "rtc_processor")
+    assert policy.rtc_processor is None
+    assert policy.model.rtc_processor is None
+    assert policy._rtc_enabled() is False
+
+    print("✓ PI0 RTC initialization without RTC config: Test passed")
+
+
+def test_pi0_rtc_inference_with_prev_chunk():
+    """Test PI0 policy inference with RTC and previous chunk."""
+    set_seed(42)
+
+    config = PI0Config(max_action_dim=7, max_state_dim=14, chunk_size=50, dtype="float32")
+
+    # Add RTC config
+    config.rtc_config = RTCConfig(
+        enabled=True,
+        execution_horizon=10,
+        max_guidance_weight=5.0,
+        prefix_attention_schedule=RTCAttentionSchedule.EXP,
+        debug=False,
+    )
+
+    config.input_features = {
+        "observation.state": PolicyFeature(type=FeatureType.STATE, shape=(14,)),
+        "observation.images.base_0_rgb": PolicyFeature(type=FeatureType.VISUAL, shape=(3, 224, 224)),
+    }
+    config.output_features = {
+        "action": PolicyFeature(type=FeatureType.ACTION, shape=(7,)),
+    }
+
+    # Create dataset stats
+    dataset_stats = {
+        "observation.state": {"mean": torch.zeros(14), "std": torch.ones(14)},
+        "action": {"mean": torch.zeros(7), "std": torch.ones(7)},
+        "observation.images.base_0_rgb": {"mean": torch.zeros(3, 224, 224), "std": torch.ones(3, 224, 224)},
+    }
+
+    # Instantiate policy and preprocessor
+    policy = PI0Policy(config)
+    policy.eval()
+    preprocessor, _ = make_pi0_pre_post_processors(config=config, dataset_stats=dataset_stats)
+
+    device = config.device
+
+    # Create dummy batch
+    batch = {
+        "observation.state": torch.randn(1, 14, dtype=torch.float32, device=device),
+        "observation.images.base_0_rgb": torch.rand(1, 3, 224, 224, dtype=torch.float32, device=device),
+        "task": ["Pick up the object"],
+    }
+    batch = preprocessor(batch)
+
+    # Create previous chunk
+    prev_chunk = torch.randn(1, 25, 7, dtype=torch.float32, device=device)
+
+    with torch.no_grad():
+        # Use same noise for fair comparison
+        noise = policy.model.sample_noise((1, config.chunk_size, 7), device)
+
+        # Test with RTC and previous chunk
+        actions_with_rtc = policy.predict_action_chunk(
+            batch,
+            noise=noise.clone(),
+            prev_chunk_left_over=prev_chunk,
+            inference_delay=4,
+            execution_horizon=10,
+        )
+
+        # Test without RTC for comparison
+        policy.config.rtc_config.enabled = False
+        actions_without_rtc = policy.predict_action_chunk(batch, noise=noise.clone())
+        policy.config.rtc_config.enabled = True
+
+    # Verify shapes
+    assert actions_with_rtc.shape == (1, config.chunk_size, 7)
+    assert actions_without_rtc.shape == (1, config.chunk_size, 7)
+
+    # With previous chunk, actions should be different (RTC guidance applied)
+    assert not torch.allclose(actions_with_rtc, actions_without_rtc, rtol=1e-3)
+
+    print("✓ PI0 RTC inference with prev_chunk: Test passed")
+
+
+@require_cuda
+def test_pi0_rtc_inference_without_prev_chunk():
+    """Test PI0 policy inference with RTC but no previous chunk (RTC should have no effect)."""
+    set_seed(42)
+
+    config = PI0Config(max_action_dim=7, max_state_dim=14, chunk_size=50, dtype="float32")
+
+    # Add RTC config
+    config.rtc_config = RTCConfig(
+        enabled=True,
+        execution_horizon=10,
+        max_guidance_weight=5.0,
+        prefix_attention_schedule=RTCAttentionSchedule.EXP,
+        debug=False,
+    )
+
+    config.input_features = {
+        "observation.state": PolicyFeature(type=FeatureType.STATE, shape=(14,)),
+        "observation.images.base_0_rgb": PolicyFeature(type=FeatureType.VISUAL, shape=(3, 224, 224)),
+    }
+    config.output_features = {
+        "action": PolicyFeature(type=FeatureType.ACTION, shape=(7,)),
+    }
+
+    # Create dataset stats
+    dataset_stats = {
+        "observation.state": {"mean": torch.zeros(14), "std": torch.ones(14)},
+        "action": {"mean": torch.zeros(7), "std": torch.ones(7)},
+        "observation.images.base_0_rgb": {"mean": torch.zeros(3, 224, 224), "std": torch.ones(3, 224, 224)},
+    }
+
+    # Instantiate policy and preprocessor
+    policy = PI0Policy(config)
+    policy.eval()
+    preprocessor, _ = make_pi0_pre_post_processors(config=config, dataset_stats=dataset_stats)
+
+    device = config.device
+
+    # Create dummy batch
+    batch = {
+        "observation.state": torch.randn(1, 14, dtype=torch.float32, device=device),
+        "observation.images.base_0_rgb": torch.rand(1, 3, 224, 224, dtype=torch.float32, device=device),
+        "task": ["Pick up the object"],
+    }
+    batch = preprocessor(batch)
+
+    with torch.no_grad():
+        # Use same noise for fair comparison
+        noise = policy.model.sample_noise((1, config.chunk_size, 7), device)
+
+        # Test with RTC enabled but no previous chunk
+        actions_with_rtc_no_prev = policy.predict_action_chunk(
+            batch,
+            noise=noise.clone(),
+            prev_chunk_left_over=None,
+        )
+
+        # Test without RTC
+        policy.config.rtc_config.enabled = False
+        actions_without_rtc = policy.predict_action_chunk(batch, noise=noise.clone())
+        policy.config.rtc_config.enabled = True
+
+    # Without previous chunk, RTC should have no effect
+    assert torch.allclose(actions_with_rtc_no_prev, actions_without_rtc, rtol=1e-5)
+
+    print("✓ PI0 RTC inference without prev_chunk: Test passed")
+
+
+@require_cuda
+def test_pi0_rtc_validation_rules():
+    """Test PI0 policy with RTC follows all three validation rules."""
+    set_seed(42)
+
+    config = PI0Config(max_action_dim=7, max_state_dim=14, chunk_size=50, dtype="float32")
+
+    # Add RTC config
+    config.rtc_config = RTCConfig(
+        enabled=True,
+        execution_horizon=10,
+        max_guidance_weight=5.0,
+        prefix_attention_schedule=RTCAttentionSchedule.EXP,
+        debug=False,
+    )
+
+    config.input_features = {
+        "observation.state": PolicyFeature(type=FeatureType.STATE, shape=(14,)),
+        "observation.images.base_0_rgb": PolicyFeature(type=FeatureType.VISUAL, shape=(3, 224, 224)),
+    }
+    config.output_features = {
+        "action": PolicyFeature(type=FeatureType.ACTION, shape=(7,)),
+    }
+
+    # Create dataset stats
+    dataset_stats = {
+        "observation.state": {"mean": torch.zeros(14), "std": torch.ones(14)},
+        "action": {"mean": torch.zeros(7), "std": torch.ones(7)},
+        "observation.images.base_0_rgb": {"mean": torch.zeros(3, 224, 224), "std": torch.ones(3, 224, 224)},
+    }
+
+    # Instantiate policy and preprocessor
+    policy = PI0Policy(config)
+    policy.eval()
+    preprocessor, _ = make_pi0_pre_post_processors(config=config, dataset_stats=dataset_stats)
+
+    device = config.device
+
+    # Create dummy batch
+    batch = {
+        "observation.state": torch.randn(1, 14, dtype=torch.float32, device=device),
+        "observation.images.base_0_rgb": torch.rand(1, 3, 224, 224, dtype=torch.float32, device=device),
+        "task": ["Pick up the object"],
+    }
+    batch = preprocessor(batch)
+
+    # Create previous chunk
+    prev_chunk = torch.randn(1, 25, 7, dtype=torch.float32, device=device)
+
+    inference_delay = 4
+    execution_horizon = 10
+
+    with torch.no_grad():
+        # Use same noise for fair comparison
+        noise = policy.model.sample_noise((1, config.chunk_size, 7), device)
+
+        # Test with RTC
+        actions_with_rtc = policy.predict_action_chunk(
+            batch,
+            noise=noise.clone(),
+            prev_chunk_left_over=prev_chunk,
+            inference_delay=inference_delay,
+            execution_horizon=execution_horizon,
+        )
+
+        # Test without RTC
+        policy.config.rtc_config.enabled = False
+        actions_without_rtc = policy.predict_action_chunk(batch, noise=noise.clone())
+        policy.config.rtc_config.enabled = True
+
+    assert not torch.allclose(actions_with_rtc, actions_without_rtc, rtol=1e-3)
+
+    """Test PI0 with different RTC attention schedules."""
+    set_seed(42)
+
+    schedules = [
+        RTCAttentionSchedule.ZEROS,
+        RTCAttentionSchedule.ONES,
+        RTCAttentionSchedule.LINEAR,
+        RTCAttentionSchedule.EXP,
+    ]
+
+    config = PI0Config(max_action_dim=7, max_state_dim=14, chunk_size=50, dtype="float32")
+
+    config.input_features = {
+        "observation.state": PolicyFeature(type=FeatureType.STATE, shape=(14,)),
+        "observation.images.base_0_rgb": PolicyFeature(type=FeatureType.VISUAL, shape=(3, 224, 224)),
+    }
+    config.output_features = {
+        "action": PolicyFeature(type=FeatureType.ACTION, shape=(7,)),
+    }
+
+    # Create dataset stats
+    dataset_stats = {
+        "observation.state": {"mean": torch.zeros(14), "std": torch.ones(14)},
+        "action": {"mean": torch.zeros(7), "std": torch.ones(7)},
+        "observation.images.base_0_rgb": {"mean": torch.zeros(3, 224, 224), "std": torch.ones(3, 224, 224)},
+    }
+
+    device = config.device
+
+    for schedule in schedules:
+        print(f"Testing schedule: {schedule}")
+
+        # Add RTC config with specific schedule
+        config.rtc_config = RTCConfig(
+            enabled=True,
+            execution_horizon=10,
+            max_guidance_weight=5.0,
+            prefix_attention_schedule=schedule,
+            debug=False,
+        )
+
+        # Instantiate policy
+        policy = PI0Policy(config)
+        policy.eval()
+        preprocessor, _ = make_pi0_pre_post_processors(config=config, dataset_stats=dataset_stats)
+
+        # Create dummy batch
+        batch = {
+            "observation.state": torch.randn(1, 14, dtype=torch.float32, device=device),
+            "observation.images.base_0_rgb": torch.rand(1, 3, 224, 224, dtype=torch.float32, device=device),
+            "task": ["Pick up the object"],
+        }
+        batch = preprocessor(batch)
+
+        # Create previous chunk
+        prev_chunk = torch.randn(1, 25, 7, dtype=torch.float32, device=device)
+
+        with torch.no_grad():
+            noise = policy.model.sample_noise((1, config.chunk_size, 7), device)
+            actions = policy.predict_action_chunk(
+                batch,
+                noise=noise,
+                prev_chunk_left_over=prev_chunk,
+                inference_delay=4,
+                execution_horizon=10,
+            )
+
+        # Verify shape
+        assert actions.shape == (1, config.chunk_size, 7)
+        print(f"  ✓ Schedule {schedule}: Test passed")
+
+    print("✓ PI0 RTC different schedules: All schedules tested")

tests/policies/rtc/test_action_queue.py

@@ -0,0 +1,825 @@
+#!/usr/bin/env python
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Tests for RTC ActionQueue module."""
+
+import threading
+import time
+
+import pytest
+import torch
+
+from lerobot.policies.rtc.action_queue import ActionQueue
+from lerobot.policies.rtc.configuration_rtc import RTCConfig
+
+# ====================== Fixtures ======================
+
+
+@pytest.fixture
+def rtc_config_enabled():
+    """Create an RTC config with RTC enabled."""
+    return RTCConfig(enabled=True, execution_horizon=10, max_guidance_weight=1.0)
+
+
+@pytest.fixture
+def rtc_config_disabled():
+    """Create an RTC config with RTC disabled."""
+    return RTCConfig(enabled=False, execution_horizon=10, max_guidance_weight=1.0)
+
+
+@pytest.fixture
+def sample_actions():
+    """Create sample action tensors for testing."""
+    return {
+        "original": torch.randn(50, 6),  # (time_steps, action_dim)
+        "processed": torch.randn(50, 6),
+        "short": torch.randn(10, 6),
+        "longer": torch.randn(100, 6),
+    }
+
+
+@pytest.fixture
+def action_queue_rtc_enabled(rtc_config_enabled):
+    """Create an ActionQueue with RTC enabled."""
+    return ActionQueue(rtc_config_enabled)
+
+
+@pytest.fixture
+def action_queue_rtc_disabled(rtc_config_disabled):
+    """Create an ActionQueue with RTC disabled."""
+    return ActionQueue(rtc_config_disabled)
+
+
+# ====================== Initialization Tests ======================
+
+
+def test_action_queue_initialization_rtc_enabled(rtc_config_enabled):
+    """Test ActionQueue initializes correctly with RTC enabled."""
+    queue = ActionQueue(rtc_config_enabled)
+    assert queue.queue is None
+    assert queue.original_queue is None
+    assert queue.last_index == 0
+    assert queue.cfg.enabled is True
+
+
+def test_action_queue_initialization_rtc_disabled(rtc_config_disabled):
+    """Test ActionQueue initializes correctly with RTC disabled."""
+    queue = ActionQueue(rtc_config_disabled)
+    assert queue.queue is None
+    assert queue.original_queue is None
+    assert queue.last_index == 0
+    assert queue.cfg.enabled is False
+
+
+# ====================== get() Tests ======================
+
+
+def test_get_returns_none_when_empty(action_queue_rtc_enabled):
+    """Test get() returns None when queue is empty."""
+    action = action_queue_rtc_enabled.get()
+    assert action is None
+
+
+def test_get_returns_actions_sequentially(action_queue_rtc_enabled, sample_actions):
+    """Test get() returns actions in sequence."""
+    # Initialize queue with actions
+    action_queue_rtc_enabled.merge(sample_actions["original"], sample_actions["processed"], real_delay=0)
+
+    # Get first action
+    action1 = action_queue_rtc_enabled.get()
+    assert action1 is not None
+    assert action1.shape == (6,)
+    assert torch.equal(action1, sample_actions["processed"][0])
+
+    # Get second action
+    action2 = action_queue_rtc_enabled.get()
+    assert action2 is not None
+    assert torch.equal(action2, sample_actions["processed"][1])
+
+
+def test_get_returns_none_after_exhaustion(action_queue_rtc_enabled, sample_actions):
+    """Test get() returns None after all actions are consumed."""
+    # Use short action sequence
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+
+    # Consume all actions
+    for _ in range(10):
+        action = action_queue_rtc_enabled.get()
+        assert action is not None
+
+    # Next get should return None
+    action = action_queue_rtc_enabled.get()
+    assert action is None
+
+
+def test_get_increments_last_index(action_queue_rtc_enabled, sample_actions):
+    """Test get() increments last_index correctly."""
+    action_queue_rtc_enabled.merge(sample_actions["original"], sample_actions["processed"], real_delay=0)
+
+    assert action_queue_rtc_enabled.last_index == 0
+    action_queue_rtc_enabled.get()
+    assert action_queue_rtc_enabled.last_index == 1
+    action_queue_rtc_enabled.get()
+    assert action_queue_rtc_enabled.last_index == 2
+
+
+# ====================== qsize() Tests ======================
+
+
+def test_qsize_returns_zero_when_empty(action_queue_rtc_enabled):
+    """Test qsize() returns 0 when queue is empty."""
+    assert action_queue_rtc_enabled.qsize() == 0
+
+
+def test_qsize_returns_correct_size(action_queue_rtc_enabled, sample_actions):
+    """Test qsize() returns correct number of remaining actions."""
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+    assert action_queue_rtc_enabled.qsize() == 10
+
+    action_queue_rtc_enabled.get()
+    assert action_queue_rtc_enabled.qsize() == 9
+
+    action_queue_rtc_enabled.get()
+    assert action_queue_rtc_enabled.qsize() == 8
+
+
+def test_qsize_after_exhaustion(action_queue_rtc_enabled, sample_actions):
+    """Test qsize() returns 0 after queue is exhausted."""
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+
+    # Consume all actions
+    for _ in range(10):
+        action_queue_rtc_enabled.get()
+
+    assert action_queue_rtc_enabled.qsize() == 0
+
+
+# ====================== empty() Tests ======================
+
+
+def test_empty_returns_true_when_empty(action_queue_rtc_enabled):
+    """Test empty() returns True when queue is empty."""
+    assert action_queue_rtc_enabled.empty() is True
+
+
+def test_empty_returns_false_when_not_empty(action_queue_rtc_enabled, sample_actions):
+    """Test empty() returns False when queue has actions."""
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+    assert action_queue_rtc_enabled.empty() is False
+
+
+def test_empty_after_partial_consumption(action_queue_rtc_enabled, sample_actions):
+    """Test empty() returns False after partial consumption."""
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+
+    action_queue_rtc_enabled.get()
+    action_queue_rtc_enabled.get()
+
+    assert action_queue_rtc_enabled.empty() is False
+
+
+def test_empty_after_full_consumption(action_queue_rtc_enabled, sample_actions):
+    """Test empty() returns True after all actions consumed."""
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+
+    # Consume all
+    for _ in range(10):
+        action_queue_rtc_enabled.get()
+
+    assert action_queue_rtc_enabled.empty() is True
+
+
+# ====================== get_action_index() Tests ======================
+
+
+def test_get_action_index_initial_value(action_queue_rtc_enabled):
+    """Test get_action_index() returns 0 initially."""
+    assert action_queue_rtc_enabled.get_action_index() == 0
+
+
+def test_get_action_index_after_consumption(action_queue_rtc_enabled, sample_actions):
+    """Test get_action_index() tracks consumption correctly."""
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+
+    assert action_queue_rtc_enabled.get_action_index() == 0
+    action_queue_rtc_enabled.get()
+    assert action_queue_rtc_enabled.get_action_index() == 1
+    action_queue_rtc_enabled.get()
+    action_queue_rtc_enabled.get()
+    assert action_queue_rtc_enabled.get_action_index() == 3
+
+
+# ====================== get_left_over() Tests ======================
+
+
+def test_get_left_over_returns_none_when_empty(action_queue_rtc_enabled):
+    """Test get_left_over() returns None when queue is empty."""
+    leftover = action_queue_rtc_enabled.get_left_over()
+    assert leftover is None
+
+
+def test_get_left_over_returns_all_when_unconsumed(action_queue_rtc_enabled, sample_actions):
+    """Test get_left_over() returns all original actions when none consumed."""
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+
+    leftover = action_queue_rtc_enabled.get_left_over()
+    assert leftover is not None
+    assert leftover.shape == (10, 6)
+    assert torch.equal(leftover, sample_actions["short"])
+
+
+def test_get_left_over_returns_remaining_after_consumption(action_queue_rtc_enabled, sample_actions):
+    """Test get_left_over() returns only remaining original actions."""
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+
+    # Consume 3 actions
+    action_queue_rtc_enabled.get()
+    action_queue_rtc_enabled.get()
+    action_queue_rtc_enabled.get()
+
+    leftover = action_queue_rtc_enabled.get_left_over()
+    assert leftover is not None
+    assert leftover.shape == (7, 6)
+    assert torch.equal(leftover, sample_actions["short"][3:])
+
+
+def test_get_left_over_returns_empty_after_exhaustion(action_queue_rtc_enabled, sample_actions):
+    """Test get_left_over() returns empty tensor after all consumed."""
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+
+    # Consume all
+    for _ in range(10):
+        action_queue_rtc_enabled.get()
+
+    leftover = action_queue_rtc_enabled.get_left_over()
+    assert leftover is not None
+    assert leftover.shape == (0, 6)
+
+
+# ====================== merge() with RTC Enabled Tests ======================
+
+
+def test_merge_replaces_queue_when_rtc_enabled(action_queue_rtc_enabled, sample_actions):
+    """Test merge() replaces queue when RTC is enabled."""
+    # Add initial actions
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+    assert action_queue_rtc_enabled.qsize() == 10
+
+    # Consume some actions
+    action_queue_rtc_enabled.get()
+    action_queue_rtc_enabled.get()
+    assert action_queue_rtc_enabled.qsize() == 8
+
+    # Merge new actions - should replace, not append
+    action_queue_rtc_enabled.merge(sample_actions["original"], sample_actions["processed"], real_delay=5)
+
+    # Queue should be replaced with new actions minus delay
+    # Original has 50 actions, delay is 5, so remaining is 45
+    assert action_queue_rtc_enabled.qsize() == 45
+    assert action_queue_rtc_enabled.get_action_index() == 0
+
+
+def test_merge_respects_real_delay(action_queue_rtc_enabled, sample_actions):
+    """Test merge() correctly applies real_delay when RTC is enabled."""
+    delay = 10
+    action_queue_rtc_enabled.merge(sample_actions["original"], sample_actions["processed"], real_delay=delay)
+
+    # Queue should have original length minus delay
+    expected_size = len(sample_actions["original"]) - delay
+    assert action_queue_rtc_enabled.qsize() == expected_size
+
+    # First action should be the one at index [delay]
+    first_action = action_queue_rtc_enabled.get()
+    assert torch.equal(first_action, sample_actions["processed"][delay])
+
+
+def test_merge_resets_last_index_when_rtc_enabled(action_queue_rtc_enabled, sample_actions):
+    """Test merge() resets last_index to 0 when RTC is enabled."""
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+    action_queue_rtc_enabled.get()
+    action_queue_rtc_enabled.get()
+    assert action_queue_rtc_enabled.last_index == 2
+
+    # Merge new actions
+    action_queue_rtc_enabled.merge(sample_actions["original"], sample_actions["processed"], real_delay=5)
+
+    assert action_queue_rtc_enabled.last_index == 0
+
+
+def test_merge_with_zero_delay(action_queue_rtc_enabled, sample_actions):
+    """Test merge() with zero delay keeps all actions."""
+    action_queue_rtc_enabled.merge(sample_actions["original"], sample_actions["processed"], real_delay=0)
+
+    assert action_queue_rtc_enabled.qsize() == len(sample_actions["original"])
+
+
+def test_merge_with_large_delay(action_queue_rtc_enabled, sample_actions):
+    """Test merge() with delay larger than action sequence."""
+    # Delay is larger than sequence length
+    delay = 100
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=delay)
+
+    # Queue should be empty (delay >= length)
+    assert action_queue_rtc_enabled.qsize() == 0
+
+
+# ====================== merge() with RTC Disabled Tests ======================
+
+
+def test_merge_appends_when_rtc_disabled(action_queue_rtc_disabled, sample_actions):
+    """Test merge() appends actions when RTC is disabled."""
+    # Add initial actions
+    action_queue_rtc_disabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+    initial_size = action_queue_rtc_disabled.qsize()
+    assert initial_size == 10
+
+    # Merge more actions
+    action_queue_rtc_disabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+
+    # Should have appended
+    assert action_queue_rtc_disabled.qsize() == initial_size + 10
+
+
+def test_merge_removes_consumed_actions_when_appending(action_queue_rtc_disabled, sample_actions):
+    """Test merge() removes consumed actions before appending when RTC is disabled."""
+    # Add initial actions
+    action_queue_rtc_disabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+    assert action_queue_rtc_disabled.qsize() == 10
+
+    # Consume 3 actions
+    action_queue_rtc_disabled.get()
+    action_queue_rtc_disabled.get()
+    action_queue_rtc_disabled.get()
+    assert action_queue_rtc_disabled.qsize() == 7
+
+    # Merge more actions
+    action_queue_rtc_disabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+
+    # Should have 7 remaining + 10 new = 17
+    assert action_queue_rtc_disabled.qsize() == 17
+
+
+def test_merge_resets_last_index_after_append(action_queue_rtc_disabled, sample_actions):
+    """Test merge() resets last_index after appending when RTC is disabled."""
+    action_queue_rtc_disabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+    action_queue_rtc_disabled.get()
+    action_queue_rtc_disabled.get()
+    assert action_queue_rtc_disabled.last_index == 2
+
+    # Merge more actions
+    action_queue_rtc_disabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+
+    # last_index should be reset to 0
+    assert action_queue_rtc_disabled.last_index == 0
+
+
+def test_merge_ignores_delay_when_rtc_disabled(action_queue_rtc_disabled, sample_actions):
+    """Test merge() ignores real_delay parameter when RTC is disabled."""
+    action_queue_rtc_disabled.merge(sample_actions["original"], sample_actions["processed"], real_delay=10)
+
+    # All actions should be in queue (delay ignored)
+    assert action_queue_rtc_disabled.qsize() == len(sample_actions["original"])
+
+
+def test_merge_first_call_with_rtc_disabled(action_queue_rtc_disabled, sample_actions):
+    """Test merge() on first call with RTC disabled."""
+    action_queue_rtc_disabled.merge(sample_actions["original"], sample_actions["processed"], real_delay=0)
+
+    assert action_queue_rtc_disabled.qsize() == len(sample_actions["original"])
+    assert action_queue_rtc_disabled.last_index == 0
+
+
+# ====================== merge() with Different Action Shapes Tests ======================
+
+
+def test_merge_with_different_action_dims():
+    """Test merge() handles actions with different dimensions."""
+    cfg = RTCConfig(enabled=True, execution_horizon=10)
+    queue = ActionQueue(cfg)
+
+    # Actions with 4 dimensions instead of 6
+    actions_4d = torch.randn(20, 4)
+    queue.merge(actions_4d, actions_4d, real_delay=5)
+
+    action = queue.get()
+    assert action.shape == (4,)
+
+
+def test_merge_with_different_lengths():
+    """Test merge() handles action sequences of varying lengths."""
+    cfg = RTCConfig(enabled=False, execution_horizon=10)
+    queue = ActionQueue(cfg)
+
+    # Add sequences of different lengths
+    queue.merge(torch.randn(10, 6), torch.randn(10, 6), real_delay=0)
+    assert queue.qsize() == 10
+
+    queue.merge(torch.randn(25, 6), torch.randn(25, 6), real_delay=0)
+    assert queue.qsize() == 35
+
+
+# ====================== merge() Delay Validation Tests ======================
+
+
+def test_merge_validates_delay_consistency(action_queue_rtc_enabled, sample_actions, caplog):
+    """Test merge() validates that real_delay matches action index difference."""
+    import logging
+
+    caplog.set_level(logging.WARNING)
+
+    # Initialize queue
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+
+    # Consume 5 actions
+    for _ in range(5):
+        action_queue_rtc_enabled.get()
+
+    # Merge with mismatched delay (should log warning)
+    # We consumed 5 actions, so index is 5. If we pass action_index_before_inference=0,
+    # then indexes_diff=5, but if real_delay=3, it will warn
+    action_queue_rtc_enabled.merge(
+        sample_actions["original"],
+        sample_actions["processed"],
+        real_delay=3,
+        action_index_before_inference=0,
+    )
+
+    # Check warning was logged
+    assert "Indexes diff is not equal to real delay" in caplog.text
+
+
+def test_merge_no_warning_when_delays_match(action_queue_rtc_enabled, sample_actions, caplog):
+    """Test merge() doesn't warn when delays are consistent."""
+    import logging
+
+    caplog.set_level(logging.WARNING)
+
+    # Initialize queue
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+
+    # Consume 5 actions
+    for _ in range(5):
+        action_queue_rtc_enabled.get()
+
+    # Merge with matching delay
+    action_queue_rtc_enabled.merge(
+        sample_actions["original"],
+        sample_actions["processed"],
+        real_delay=5,
+        action_index_before_inference=0,
+    )
+
+    # Should not have warning
+    assert "Indexes diff is not equal to real delay" not in caplog.text
+
+
+def test_merge_skips_validation_when_action_index_none(action_queue_rtc_enabled, sample_actions, caplog):
+    """Test merge() skips delay validation when action_index_before_inference is None."""
+    import logging
+
+    caplog.set_level(logging.WARNING)
+
+    action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+
+    for _ in range(5):
+        action_queue_rtc_enabled.get()
+
+    # Pass None for action_index_before_inference
+    action_queue_rtc_enabled.merge(
+        sample_actions["original"],
+        sample_actions["processed"],
+        real_delay=999,  # Doesn't matter
+        action_index_before_inference=None,
+    )
+
+    # Should not warn (validation skipped)
+    assert "Indexes diff is not equal to real delay" not in caplog.text
+
+
+# ====================== Thread Safety Tests ======================
+
+
+def test_get_is_thread_safe(action_queue_rtc_enabled, sample_actions):
+    """Test get() is thread-safe with multiple consumers."""
+    action_queue_rtc_enabled.merge(sample_actions["longer"], sample_actions["longer"], real_delay=0)
+
+    results = []
+    errors = []
+
+    def consumer():
+        try:
+            for _ in range(25):
+                action = action_queue_rtc_enabled.get()
+                if action is not None:
+                    results.append(action)
+                time.sleep(0.001)
+        except Exception as e:
+            errors.append(e)
+
+    threads = [threading.Thread(target=consumer) for _ in range(4)]
+
+    for t in threads:
+        t.start()
+
+    for t in threads:
+        t.join()
+
+    # Should not have errors
+    assert len(errors) == 0
+
+    # Should have consumed all actions (100 total, 4 threads * 25 each)
+    assert len(results) == 100
+
+    # All results should be unique (no duplicate consumption)
+    # We can verify by checking that indices are not duplicated
+    # Since we don't track indices in results, we check total count is correct
+    assert action_queue_rtc_enabled.qsize() == 0
+
+
+def test_merge_is_thread_safe(action_queue_rtc_disabled, sample_actions):
+    """Test merge() is thread-safe with multiple producers."""
+    errors = []
+
+    def producer():
+        try:
+            for _ in range(5):
+                action_queue_rtc_disabled.merge(
+                    sample_actions["short"], sample_actions["short"], real_delay=0
+                )
+                time.sleep(0.001)
+        except Exception as e:
+            errors.append(e)
+
+    threads = [threading.Thread(target=producer) for _ in range(3)]
+
+    for t in threads:
+        t.start()
+
+    for t in threads:
+        t.join()
+
+    # Should not have errors
+    assert len(errors) == 0
+
+    # Should have accumulated all actions (3 threads * 5 merges * 10 actions = 150)
+    assert action_queue_rtc_disabled.qsize() == 150
+
+
+def test_concurrent_get_and_merge(action_queue_rtc_disabled, sample_actions):
+    """Test concurrent get() and merge() operations."""
+    errors = []
+    consumed_count = [0]
+
+    def consumer():
+        try:
+            for _ in range(50):
+                action = action_queue_rtc_disabled.get()
+                if action is not None:
+                    consumed_count[0] += 1
+                time.sleep(0.001)
+        except Exception as e:
+            errors.append(e)
+
+    def producer():
+        try:
+            for _ in range(10):
+                action_queue_rtc_disabled.merge(
+                    sample_actions["short"], sample_actions["short"], real_delay=0
+                )
+                time.sleep(0.005)
+        except Exception as e:
+            errors.append(e)
+
+    consumer_threads = [threading.Thread(target=consumer) for _ in range(2)]
+    producer_threads = [threading.Thread(target=producer) for _ in range(2)]
+
+    for t in consumer_threads + producer_threads:
+        t.start()
+
+    for t in consumer_threads + producer_threads:
+        t.join()
+
+    # Should not have errors
+    assert len(errors) == 0
+
+    # Should have consumed some or all actions (non-deterministic due to timing)
+    # Total produced: 2 producers * 10 merges * 10 actions = 200
+    # Total consumed attempts: 2 consumers * 50 = 100
+    assert consumed_count[0] <= 200
+
+
+# ====================== get_left_over() Thread Safety Tests ======================
+
+
+def test_get_left_over_is_thread_safe(action_queue_rtc_enabled, sample_actions):
+    """Test get_left_over() is thread-safe with concurrent access."""
+    action_queue_rtc_enabled.merge(sample_actions["longer"], sample_actions["longer"], real_delay=0)
+
+    errors = []
+    leftovers = []
+
+    def reader():
+        try:
+            for _ in range(20):
+                leftover = action_queue_rtc_enabled.get_left_over()
+                if leftover is not None:
+                    leftovers.append(leftover.shape[0])
+                time.sleep(0.001)
+        except Exception as e:
+            errors.append(e)
+
+    threads = [threading.Thread(target=reader) for _ in range(3)]
+
+    # Also consume some actions concurrently
+    def consumer():
+        try:
+            for _ in range(10):
+                action_queue_rtc_enabled.get()
+                time.sleep(0.002)
+        except Exception as e:
+            errors.append(e)
+
+    consumer_thread = threading.Thread(target=consumer)
+
+    all_threads = threads + [consumer_thread]
+
+    for t in all_threads:
+        t.start()
+
+    for t in all_threads:
+        t.join()
+
+    # Should not have errors
+    assert len(errors) == 0
+
+    # Leftovers should be monotonically decreasing or stable
+    # (as actions are consumed, leftover size decreases)
+    assert len(leftovers) > 0
+
+
+# ====================== Edge Cases Tests ======================
+
+
+def test_queue_with_single_action(action_queue_rtc_enabled):
+    """Test queue behavior with a single action."""
+    single_action_original = torch.randn(1, 6)
+    single_action_processed = torch.randn(1, 6)
+
+    action_queue_rtc_enabled.merge(single_action_original, single_action_processed, real_delay=0)
+
+    assert action_queue_rtc_enabled.qsize() == 1
+    action = action_queue_rtc_enabled.get()
+    assert action is not None
+    assert action.shape == (6,)
+    assert action_queue_rtc_enabled.qsize() == 0
+
+
+def test_queue_behavior_after_multiple_merge_cycles(action_queue_rtc_enabled, sample_actions):
+    """Test queue maintains correct state through multiple merge cycles."""
+    for _ in range(5):
+        action_queue_rtc_enabled.merge(sample_actions["short"], sample_actions["short"], real_delay=0)
+
+        # Consume half
+        for _ in range(5):
+            action_queue_rtc_enabled.get()
+
+        # Merge again
+        action_queue_rtc_enabled.merge(sample_actions["original"], sample_actions["processed"], real_delay=3)
+
+        assert action_queue_rtc_enabled.qsize() > 0
+
+
+def test_queue_with_all_zeros_actions(action_queue_rtc_enabled):
+    """Test queue handles all-zero action tensors."""
+    zeros_actions = torch.zeros(20, 6)
+    action_queue_rtc_enabled.merge(zeros_actions, zeros_actions, real_delay=0)
+
+    action = action_queue_rtc_enabled.get()
+    assert torch.all(action == 0)
+
+
+def test_queue_clones_input_tensors(action_queue_rtc_enabled, sample_actions):
+    """Test that merge() clones input tensors, not storing references."""
+    original_copy = sample_actions["original"].clone()
+    processed_copy = sample_actions["processed"].clone()
+
+    action_queue_rtc_enabled.merge(sample_actions["original"], sample_actions["processed"], real_delay=0)
+
+    # Modify original tensors
+    sample_actions["original"].fill_(999.0)
+    sample_actions["processed"].fill_(-999.0)
+
+    # Queue should have cloned values
+    action = action_queue_rtc_enabled.get()
+    assert not torch.equal(action, sample_actions["processed"][0])
+    assert torch.equal(action, processed_copy[0])
+
+    leftover = action_queue_rtc_enabled.get_left_over()
+    assert not torch.equal(leftover, sample_actions["original"][1:])
+    assert torch.equal(leftover, original_copy[1:])
+
+
+@pytest.mark.skipif(not torch.cuda.is_available(), reason="CUDA not available")
+def test_queue_handles_gpu_tensors():
+    """Test queue correctly handles GPU tensors."""
+    cfg = RTCConfig(enabled=True, execution_horizon=10)
+    queue = ActionQueue(cfg)
+
+    actions_gpu = torch.randn(20, 6, device="cuda")
+    queue.merge(actions_gpu, actions_gpu, real_delay=0)
+
+    action = queue.get()
+    assert action.device.type == "cuda"
+
+    leftover = queue.get_left_over()
+    assert leftover.device.type == "cuda"
+
+
+def test_queue_handles_different_dtypes():
+    """Test queue handles actions with different dtypes."""
+    cfg = RTCConfig(enabled=True, execution_horizon=10)
+    queue = ActionQueue(cfg)
+
+    # Use float64 instead of default float32
+    actions_f64 = torch.randn(20, 6, dtype=torch.float64)
+    queue.merge(actions_f64, actions_f64, real_delay=0)
+
+    action = queue.get()
+    assert action.dtype == torch.float64
+
+
+def test_empty_with_none_queue(action_queue_rtc_enabled):
+    """Test empty() correctly handles None queue."""
+    assert action_queue_rtc_enabled.queue is None
+    assert action_queue_rtc_enabled.empty() is True
+
+
+def test_qsize_with_none_queue(action_queue_rtc_enabled):
+    """Test qsize() correctly handles None queue."""
+    assert action_queue_rtc_enabled.queue is None
+    assert action_queue_rtc_enabled.qsize() == 0
+
+
+# ====================== Integration Tests ======================
+
+
+def test_typical_rtc_workflow(action_queue_rtc_enabled, sample_actions):
+    """Test a typical RTC workflow: merge, consume, merge with delay."""
+    # First inference
+    action_queue_rtc_enabled.merge(sample_actions["original"], sample_actions["processed"], real_delay=0)
+    initial_size = action_queue_rtc_enabled.qsize()
+    assert initial_size == 50
+
+    # Consume 10 actions (execution_horizon)
+    for _ in range(10):
+        action = action_queue_rtc_enabled.get()
+        assert action is not None
+
+    assert action_queue_rtc_enabled.qsize() == 40
+
+    # Second inference with delay
+    action_index_before = action_queue_rtc_enabled.get_action_index()
+
+    action_queue_rtc_enabled.merge(
+        sample_actions["original"],
+        sample_actions["processed"],
+        real_delay=5,
+        action_index_before_inference=action_index_before,
+    )
+
+    # Queue should be replaced, minus delay
+    assert action_queue_rtc_enabled.qsize() == 45
+    assert action_queue_rtc_enabled.get_action_index() == 0
+
+
+def test_typical_non_rtc_workflow(action_queue_rtc_disabled, sample_actions):
+    """Test a typical non-RTC workflow: merge, consume, merge again."""
+    # First inference
+    action_queue_rtc_disabled.merge(sample_actions["original"], sample_actions["processed"], real_delay=0)
+    assert action_queue_rtc_disabled.qsize() == 50
+
+    # Consume 40 actions
+    for _ in range(40):
+        action = action_queue_rtc_disabled.get()
+        assert action is not None
+
+    assert action_queue_rtc_disabled.qsize() == 10
+
+    # Second inference (should append)
+    action_queue_rtc_disabled.merge(sample_actions["original"], sample_actions["processed"], real_delay=0)
+
+    # Should have 10 remaining + 50 new = 60
+    assert action_queue_rtc_disabled.qsize() == 60

tests/policies/rtc/test_configuration_rtc.py

@@ -0,0 +1,65 @@
+#!/usr/bin/env python
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Tests for RTC configuration module."""
+
+from lerobot.configs.types import RTCAttentionSchedule
+from lerobot.policies.rtc.configuration_rtc import RTCConfig
+
+# ====================== Initialization Tests ======================
+
+
+def test_rtc_config_default_initialization():
+    """Test RTCConfig initializes with default values."""
+    config = RTCConfig()
+
+    assert config.enabled is False
+    assert config.prefix_attention_schedule == RTCAttentionSchedule.LINEAR
+    assert config.max_guidance_weight == 10.0
+    assert config.execution_horizon == 10
+    assert config.debug is False
+    assert config.debug_maxlen == 100
+
+
+def test_rtc_config_custom_initialization():
+    """Test RTCConfig initializes with custom values."""
+    config = RTCConfig(
+        enabled=True,
+        prefix_attention_schedule=RTCAttentionSchedule.EXP,
+        max_guidance_weight=5.0,
+        execution_horizon=20,
+        debug=True,
+        debug_maxlen=200,
+    )
+
+    assert config.enabled is True
+    assert config.prefix_attention_schedule == RTCAttentionSchedule.EXP
+    assert config.max_guidance_weight == 5.0
+    assert config.execution_horizon == 20
+    assert config.debug is True
+    assert config.debug_maxlen == 200
+
+
+def test_rtc_config_partial_initialization():
+    """Test RTCConfig with partial custom values."""
+    config = RTCConfig(enabled=True, max_guidance_weight=15.0)
+
+    assert config.enabled is True
+    assert config.max_guidance_weight == 15.0
+    # Other values should be defaults
+    assert config.prefix_attention_schedule == RTCAttentionSchedule.LINEAR
+    assert config.execution_horizon == 10
+    assert config.debug is False

tests/policies/rtc/test_debug_tracker.py

@@ -0,0 +1,488 @@
+#!/usr/bin/env python
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Tests for RTC debug tracker module."""
+
+import pytest
+import torch
+
+from lerobot.policies.rtc.debug_tracker import DebugStep, Tracker
+
+# ====================== Fixtures ======================
+
+
+@pytest.fixture
+def sample_tensors():
+    """Create sample tensors for testing."""
+    return {
+        "x_t": torch.randn(1, 50, 6),
+        "v_t": torch.randn(1, 50, 6),
+        "x1_t": torch.randn(1, 50, 6),
+        "correction": torch.randn(1, 50, 6),
+        "err": torch.randn(1, 50, 6),
+        "weights": torch.randn(1, 50, 1),
+    }
+
+
+@pytest.fixture
+def enabled_tracker():
+    """Create an enabled tracker with default settings."""
+    return Tracker(enabled=True, maxlen=100)
+
+
+@pytest.fixture
+def disabled_tracker():
+    """Create a disabled tracker."""
+    return Tracker(enabled=False)
+
+
+# ====================== DebugStep Tests ======================
+
+
+def test_debug_step_initialization():
+    """Test that DebugStep can be initialized with default values."""
+    step = DebugStep()
+    assert step.step_idx == 0
+    assert step.x_t is None
+    assert step.v_t is None
+    assert step.x1_t is None
+    assert step.correction is None
+    assert step.err is None
+    assert step.weights is None
+    assert step.guidance_weight is None
+    assert step.time is None
+    assert step.inference_delay is None
+    assert step.execution_horizon is None
+    assert step.metadata == {}
+
+
+def test_debug_step_with_values(sample_tensors):
+    """Test DebugStep initialization with actual values."""
+    step = DebugStep(
+        step_idx=5,
+        x_t=sample_tensors["x_t"],
+        v_t=sample_tensors["v_t"],
+        x1_t=sample_tensors["x1_t"],
+        correction=sample_tensors["correction"],
+        err=sample_tensors["err"],
+        weights=sample_tensors["weights"],
+        guidance_weight=2.5,
+        time=0.8,
+        inference_delay=4,
+        execution_horizon=8,
+        metadata={"custom_key": "custom_value"},
+    )
+
+    assert step.step_idx == 5
+    assert torch.equal(step.x_t, sample_tensors["x_t"])
+    assert torch.equal(step.v_t, sample_tensors["v_t"])
+    assert torch.equal(step.x1_t, sample_tensors["x1_t"])
+    assert torch.equal(step.correction, sample_tensors["correction"])
+    assert torch.equal(step.err, sample_tensors["err"])
+    assert torch.equal(step.weights, sample_tensors["weights"])
+    assert step.guidance_weight == 2.5
+    assert step.time == 0.8
+    assert step.inference_delay == 4
+    assert step.execution_horizon == 8
+    assert step.metadata == {"custom_key": "custom_value"}
+
+
+def test_debug_step_to_dict_without_tensors(sample_tensors):
+    """Test converting DebugStep to dictionary without tensor values."""
+    step = DebugStep(
+        step_idx=3,
+        x_t=sample_tensors["x_t"],
+        v_t=sample_tensors["v_t"],
+        guidance_weight=torch.tensor(3.0),
+        time=torch.tensor(0.5),
+        inference_delay=2,
+        execution_horizon=10,
+    )
+
+    result = step.to_dict(include_tensors=False)
+
+    assert result["step_idx"] == 3
+    assert result["guidance_weight"] == 3.0
+    assert result["time"] == 0.5
+    assert result["inference_delay"] == 2
+    assert result["execution_horizon"] == 10
+
+    # Check tensor statistics are included
+    assert "x_t_stats" in result
+    assert "v_t_stats" in result
+    assert "x1_t_stats" not in result  # x1_t was None
+
+    # Verify statistics structure
+    assert "shape" in result["x_t_stats"]
+    assert "mean" in result["x_t_stats"]
+    assert "std" in result["x_t_stats"]
+    assert "min" in result["x_t_stats"]
+    assert "max" in result["x_t_stats"]
+
+    # Verify shape matches original tensor
+    assert result["x_t_stats"]["shape"] == tuple(sample_tensors["x_t"].shape)
+
+
+def test_debug_step_to_dict_with_tensors(sample_tensors):
+    """Test converting DebugStep to dictionary with tensor values."""
+    step = DebugStep(
+        step_idx=1,
+        x_t=sample_tensors["x_t"],
+        v_t=sample_tensors["v_t"],
+        guidance_weight=1.5,
+        time=0.9,
+    )
+
+    result = step.to_dict(include_tensors=True)
+
+    assert result["step_idx"] == 1
+    assert result["guidance_weight"] == 1.5
+    assert result["time"] == 0.9
+
+    # Check tensors are included (as CPU tensors)
+    assert "x_t" in result
+    assert "v_t" in result
+    assert isinstance(result["x_t"], torch.Tensor)
+    assert isinstance(result["v_t"], torch.Tensor)
+    assert result["x_t"].device.type == "cpu"
+    assert result["v_t"].device.type == "cpu"
+
+
+def test_debug_step_to_dict_with_none_guidance_weight():
+    """Test to_dict handles None guidance_weight correctly."""
+    step = DebugStep(step_idx=0, time=1.0, guidance_weight=None)
+    result = step.to_dict(include_tensors=False)
+    assert result["guidance_weight"] is None
+
+
+def test_tracker_initialization_enabled():
+    """Test tracker initialization when enabled."""
+    tracker = Tracker(enabled=True, maxlen=50)
+    assert tracker.enabled is True
+    assert tracker._steps == {}
+    assert tracker._maxlen == 50
+    assert tracker._step_counter == 0
+    assert len(tracker) == 0
+
+
+def test_tracker_reset_when_enabled(enabled_tracker, sample_tensors):
+    """Test reset clears all steps when tracker is enabled."""
+    # Add some steps
+    enabled_tracker.track(time=1.0, x_t=sample_tensors["x_t"])
+    enabled_tracker.track(time=0.9, x_t=sample_tensors["x_t"])
+    assert len(enabled_tracker) == 2
+
+    # Reset
+    enabled_tracker.reset()
+    assert len(enabled_tracker) == 0
+    assert enabled_tracker._step_counter == 0
+    assert enabled_tracker._steps == {}
+
+
+def test_tracker_reset_when_disabled(disabled_tracker):
+    """Test reset on disabled tracker doesn't cause errors."""
+    disabled_tracker.reset()
+    assert len(disabled_tracker) == 0
+
+
+# ====================== Tracker.track() Tests ======================
+
+
+def test_track_creates_new_step(enabled_tracker, sample_tensors):
+    """Test that track creates a new step when time doesn't exist."""
+    enabled_tracker.track(
+        time=1.0,
+        x_t=sample_tensors["x_t"],
+        v_t=sample_tensors["v_t"],
+        guidance_weight=5.0,
+        inference_delay=4,
+        execution_horizon=8,
+    )
+
+    assert len(enabled_tracker) == 1
+    steps = enabled_tracker.get_all_steps()
+    assert len(steps) == 1
+    assert steps[0].step_idx == 0
+    assert steps[0].time == 1.0
+    assert torch.equal(steps[0].x_t, sample_tensors["x_t"])
+    assert torch.equal(steps[0].v_t, sample_tensors["v_t"])
+    assert steps[0].guidance_weight == 5.0
+    assert steps[0].inference_delay == 4
+    assert steps[0].execution_horizon == 8
+
+
+def test_track_updates_existing_step(enabled_tracker, sample_tensors):
+    """Test that track updates an existing step at the same time."""
+    # Create initial step
+    enabled_tracker.track(time=0.9, x_t=sample_tensors["x_t"])
+    assert len(enabled_tracker) == 1
+    steps = enabled_tracker.get_all_steps()
+    assert steps[0].v_t is None
+
+    # Update the same timestep with v_t
+    enabled_tracker.track(time=0.9, v_t=sample_tensors["v_t"])
+    assert len(enabled_tracker) == 1  # Still only one step
+    steps = enabled_tracker.get_all_steps()
+    assert torch.equal(steps[0].x_t, sample_tensors["x_t"])  # Original x_t preserved
+    assert torch.equal(steps[0].v_t, sample_tensors["v_t"])  # New v_t added
+
+
+def test_track_with_tensor_time(enabled_tracker, sample_tensors):
+    """Test track handles tensor time values correctly."""
+    time_tensor = torch.tensor(0.8)
+    enabled_tracker.track(time=time_tensor, x_t=sample_tensors["x_t"])
+
+    steps = enabled_tracker.get_all_steps()
+    assert len(steps) == 1
+    assert abs(steps[0].time - 0.8) < 1e-6  # Use approximate comparison for floating point
+
+
+def test_track_time_rounding(enabled_tracker, sample_tensors):
+    """Test that track rounds time to avoid floating point precision issues."""
+    # These times should be treated as the same after rounding to 6 decimals
+    enabled_tracker.track(time=0.9000001, x_t=sample_tensors["x_t"])
+    enabled_tracker.track(time=0.9000002, v_t=sample_tensors["v_t"])
+
+    # Should still be one step (times rounded to same value)
+    assert len(enabled_tracker) == 1
+    steps = enabled_tracker.get_all_steps()
+    assert torch.equal(steps[0].x_t, sample_tensors["x_t"])
+    assert torch.equal(steps[0].v_t, sample_tensors["v_t"])
+
+
+def test_track_does_nothing_when_disabled(disabled_tracker, sample_tensors):
+    """Test that track does nothing when tracker is disabled."""
+    disabled_tracker.track(time=1.0, x_t=sample_tensors["x_t"])
+    assert len(disabled_tracker) == 0
+
+
+def test_track_with_metadata(enabled_tracker, sample_tensors):
+    """Test track stores custom metadata."""
+    enabled_tracker.track(time=0.7, x_t=sample_tensors["x_t"], custom_field="custom_value", count=42)
+
+    steps = enabled_tracker.get_all_steps()
+    assert steps[0].metadata["custom_field"] == "custom_value"
+    assert steps[0].metadata["count"] == 42
+
+
+def test_track_updates_metadata(enabled_tracker):
+    """Test that track updates metadata for existing steps."""
+    enabled_tracker.track(time=0.6, meta1="value1")
+    enabled_tracker.track(time=0.6, meta2="value2")
+
+    steps = enabled_tracker.get_all_steps()
+    assert steps[0].metadata["meta1"] == "value1"
+    assert steps[0].metadata["meta2"] == "value2"
+
+
+def test_track_clones_tensors(enabled_tracker, sample_tensors):
+    """Test that track clones tensors instead of storing references."""
+    x_t_original = sample_tensors["x_t"].clone()
+    enabled_tracker.track(time=0.5, x_t=sample_tensors["x_t"])
+
+    # Modify original tensor
+    sample_tensors["x_t"].fill_(999.0)
+
+    # Tracked tensor should not be affected
+    steps = enabled_tracker.get_all_steps()
+    assert not torch.equal(steps[0].x_t, sample_tensors["x_t"])
+    assert torch.equal(steps[0].x_t, x_t_original)
+
+
+def test_track_with_none_values(enabled_tracker):
+    """Test track handles None values correctly."""
+    enabled_tracker.track(
+        time=0.4,
+        x_t=None,
+        v_t=None,
+        guidance_weight=None,
+        inference_delay=None,
+    )
+
+    steps = enabled_tracker.get_all_steps()
+    assert len(steps) == 1
+    assert steps[0].x_t is None
+    assert steps[0].v_t is None
+    assert steps[0].guidance_weight is None
+    assert steps[0].inference_delay is None
+
+
+def test_track_updates_only_non_none_fields(enabled_tracker, sample_tensors):
+    """Test that update preserves existing values when None is passed."""
+    # Create step with x_t
+    enabled_tracker.track(time=0.3, x_t=sample_tensors["x_t"], guidance_weight=2.0)
+
+    # Update with v_t only (pass None for other fields)
+    enabled_tracker.track(time=0.3, v_t=sample_tensors["v_t"], x_t=None, guidance_weight=None)
+
+    # Original values should be preserved
+    steps = enabled_tracker.get_all_steps()
+    assert torch.equal(steps[0].x_t, sample_tensors["x_t"])  # Still has x_t
+    assert torch.equal(steps[0].v_t, sample_tensors["v_t"])  # Now has v_t
+    assert steps[0].guidance_weight == 2.0  # Still has guidance_weight
+
+
+# ====================== Tracker.maxlen Tests ======================
+
+
+def test_tracker_enforces_maxlen():
+    """Test that tracker enforces maxlen limit."""
+    tracker = Tracker(enabled=True, maxlen=3)
+
+    # Add 5 steps
+    for i in range(5):
+        time = 1.0 - i * 0.1  # 1.0, 0.9, 0.8, 0.7, 0.6
+        tracker.track(time=time, x_t=torch.randn(1, 10, 6))
+
+    # Should only keep the last 3
+    assert len(tracker) == 3
+
+    # Verify oldest steps were removed (should have 0.6, 0.7, 0.8)
+    steps = tracker.get_all_steps()
+    times = sorted([step.time for step in steps])
+    assert times == [0.6, 0.7, 0.8]
+
+
+def test_tracker_step_idx_increments_despite_maxlen():
+    """Test that step_idx continues incrementing even when maxlen is enforced."""
+    tracker = Tracker(enabled=True, maxlen=2)
+
+    # Add 4 steps
+    for i in range(4):
+        time = 1.0 - i * 0.1
+        tracker.track(time=time, x_t=torch.randn(1, 10, 6))
+
+    # Should have 2 steps with step_idx 2 and 3 (oldest removed)
+    steps = sorted(tracker.get_all_steps(), key=lambda s: s.step_idx)
+    assert len(steps) == 2
+    assert steps[0].step_idx == 2
+    assert steps[1].step_idx == 3
+
+
+def test_tracker_without_maxlen_keeps_all():
+    """Test that tracker without maxlen keeps all steps."""
+    tracker = Tracker(enabled=True, maxlen=None)
+
+    # Add 100 steps
+    for i in range(100):
+        time = 1.0 - i * 0.01
+        tracker.track(time=time, x_t=torch.randn(1, 10, 6))
+
+    assert len(tracker) == 100
+
+
+def test_get_all_steps_returns_empty_when_disabled(disabled_tracker):
+    """Test get_all_steps returns empty list when disabled."""
+    steps = disabled_tracker.get_all_steps()
+    assert steps == []
+    assert isinstance(steps, list)
+
+
+def test_get_all_steps_returns_empty_when_no_steps(enabled_tracker):
+    """Test get_all_steps returns empty list when no steps tracked."""
+    steps = enabled_tracker.get_all_steps()
+    assert steps == []
+
+
+def test_get_all_steps_returns_all_tracked_steps(enabled_tracker, sample_tensors):
+    """Test get_all_steps returns all tracked steps."""
+    # Track 5 steps
+    for i in range(5):
+        time = 1.0 - i * 0.1
+        enabled_tracker.track(time=time, x_t=sample_tensors["x_t"])
+
+    steps = enabled_tracker.get_all_steps()
+    assert len(steps) == 5
+
+    # Verify all are DebugStep instances
+    for step in steps:
+        assert isinstance(step, DebugStep)
+
+
+def test_get_all_steps_preserves_insertion_order(enabled_tracker):
+    """Test that get_all_steps preserves insertion order (Python 3.7+)."""
+    times = [0.9, 0.8, 0.7, 0.6, 0.5]
+    for time in times:
+        enabled_tracker.track(time=time, x_t=torch.randn(1, 10, 6))
+
+    steps = enabled_tracker.get_all_steps()
+    retrieved_times = [step.time for step in steps]
+
+    # Should be in insertion order
+    assert retrieved_times == times
+
+
+# ====================== Tracker.__len__() Tests ======================
+
+
+def test_len_returns_zero_when_disabled(disabled_tracker):
+    """Test __len__ returns 0 when tracker is disabled."""
+    assert len(disabled_tracker) == 0
+
+
+def test_len_returns_zero_when_empty(enabled_tracker):
+    """Test __len__ returns 0 when no steps are tracked."""
+    assert len(enabled_tracker) == 0
+
+
+def test_len_returns_correct_count(enabled_tracker, sample_tensors):
+    """Test __len__ returns correct number of tracked steps."""
+    assert len(enabled_tracker) == 0
+
+    enabled_tracker.track(time=1.0, x_t=sample_tensors["x_t"])
+    assert len(enabled_tracker) == 1
+
+    enabled_tracker.track(time=0.9, x_t=sample_tensors["x_t"])
+    assert len(enabled_tracker) == 2
+
+    enabled_tracker.track(time=0.8, x_t=sample_tensors["x_t"])
+    assert len(enabled_tracker) == 3
+
+
+def test_len_after_reset(enabled_tracker, sample_tensors):
+    """Test __len__ returns 0 after reset."""
+    enabled_tracker.track(time=1.0, x_t=sample_tensors["x_t"])
+    enabled_tracker.track(time=0.9, x_t=sample_tensors["x_t"])
+    assert len(enabled_tracker) == 2
+
+    enabled_tracker.reset()
+    assert len(enabled_tracker) == 0
+
+
+@pytest.mark.skipif(not torch.cuda.is_available(), reason="CUDA not available")
+def test_tracker_handles_gpu_tensors():
+    """Test tracker correctly handles GPU tensors."""
+    tracker = Tracker(enabled=True, maxlen=10)
+    x_t_gpu = torch.randn(1, 50, 6, device="cuda")
+
+    tracker.track(time=1.0, x_t=x_t_gpu)
+
+    steps = tracker.get_all_steps()
+    # Tracker should clone and detach tensors
+    assert steps[0].x_t.device.type == "cuda"
+
+
+def test_tracker_with_varying_tensor_shapes(enabled_tracker):
+    """Test tracker handles varying tensor shapes across steps."""
+    enabled_tracker.track(time=1.0, x_t=torch.randn(1, 50, 6))
+    enabled_tracker.track(time=0.9, x_t=torch.randn(1, 25, 6))
+    enabled_tracker.track(time=0.8, x_t=torch.randn(2, 50, 8))
+
+    steps = enabled_tracker.get_all_steps()
+    assert len(steps) == 3
+    assert steps[0].x_t.shape == (1, 50, 6)
+    assert steps[1].x_t.shape == (1, 25, 6)
+    assert steps[2].x_t.shape == (2, 50, 8)

tests/policies/rtc/test_latency_tracker.py

@@ -0,0 +1,322 @@
+#!/usr/bin/env python
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Tests for RTC LatencyTracker module."""
+
+import pytest
+
+from lerobot.policies.rtc.latency_tracker import LatencyTracker
+
+# ====================== Fixtures ======================
+
+
+@pytest.fixture
+def tracker():
+    """Create a LatencyTracker with default maxlen."""
+    return LatencyTracker(maxlen=100)
+
+
+@pytest.fixture
+def small_tracker():
+    """Create a LatencyTracker with small maxlen for overflow testing."""
+    return LatencyTracker(maxlen=5)
+
+
+# ====================== Initialization Tests ======================
+
+
+def test_latency_tracker_initialization():
+    """Test LatencyTracker initializes correctly."""
+    tracker = LatencyTracker(maxlen=50)
+    assert len(tracker) == 0
+    assert tracker.max_latency == 0.0
+    assert tracker.max() == 0.0
+
+
+def test_latency_tracker_default_maxlen():
+    """Test LatencyTracker uses default maxlen."""
+    tracker = LatencyTracker()
+    # Should accept default maxlen=100
+    assert len(tracker) == 0
+
+
+# ====================== add() Tests ======================
+
+
+def test_add_single_latency(tracker):
+    """Test adding a single latency value."""
+    tracker.add(0.5)
+    assert len(tracker) == 1
+    assert tracker.max() == 0.5
+
+
+def test_add_multiple_latencies(tracker):
+    """Test adding multiple latency values."""
+    latencies = [0.1, 0.5, 0.3, 0.8, 0.2]
+    for lat in latencies:
+        tracker.add(lat)
+
+    assert len(tracker) == 5
+    assert tracker.max() == 0.8
+
+
+def test_add_negative_latency_ignored(tracker):
+    """Test that negative latencies are ignored."""
+    tracker.add(0.5)
+    tracker.add(-0.1)
+    tracker.add(0.3)
+
+    # Should only have 2 valid latencies
+    assert len(tracker) == 2
+    assert tracker.max() == 0.5
+
+
+def test_add_zero_latency(tracker):
+    """Test adding zero latency."""
+    tracker.add(0.0)
+    assert len(tracker) == 1
+    assert tracker.max() == 0.0
+
+
+def test_add_converts_to_float(tracker):
+    """Test add() converts input to float."""
+    tracker.add(5)  # Integer
+    tracker.add("3.5")  # String
+
+    assert len(tracker) == 2
+    assert tracker.max() == 5.0
+
+
+def test_add_updates_max_latency(tracker):
+    """Test that max_latency is updated correctly."""
+    tracker.add(0.5)
+    assert tracker.max_latency == 0.5
+
+    tracker.add(0.3)
+    assert tracker.max_latency == 0.5  # Should not decrease
+
+    tracker.add(0.9)
+    assert tracker.max_latency == 0.9  # Should increase
+
+
+# ====================== reset() Tests ======================
+
+
+def test_reset_clears_values(tracker):
+    """Test reset() clears all values."""
+    tracker.add(0.5)
+    tracker.add(0.8)
+    tracker.add(0.3)
+    assert len(tracker) == 3
+
+    tracker.reset()
+    assert len(tracker) == 0
+    assert tracker.max_latency == 0.0
+
+
+def test_reset_clears_max_latency(tracker):
+    """Test reset() resets max_latency."""
+    tracker.add(1.5)
+    assert tracker.max_latency == 1.5
+
+    tracker.reset()
+    assert tracker.max_latency == 0.0
+
+
+def test_reset_allows_new_values(tracker):
+    """Test that tracker works correctly after reset."""
+    tracker.add(0.5)
+    tracker.reset()
+
+    tracker.add(0.3)
+    assert len(tracker) == 1
+    assert tracker.max() == 0.3
+
+
+# ====================== max() Tests ======================
+
+
+def test_max_returns_zero_when_empty(tracker):
+    """Test max() returns 0.0 when tracker is empty."""
+    assert tracker.max() == 0.0
+
+
+def test_max_returns_maximum_value(tracker):
+    """Test max() returns the maximum latency."""
+    latencies = [0.2, 0.8, 0.3, 0.5, 0.1]
+    for lat in latencies:
+        tracker.add(lat)
+
+    assert tracker.max() == 0.8
+
+
+def test_max_persists_after_sliding_window(small_tracker):
+    """Test max() persists even after values slide out of window."""
+    # Add values that will exceed maxlen=5
+    small_tracker.add(0.1)
+    small_tracker.add(0.9)  # This is max
+    small_tracker.add(0.2)
+    small_tracker.add(0.3)
+    small_tracker.add(0.4)
+    small_tracker.add(0.5)  # This pushes out 0.1
+
+    # Max should still be 0.9 even though only last 5 values kept
+    assert small_tracker.max() == 0.9
+
+
+def test_max_after_reset(tracker):
+    """Test max() returns 0.0 after reset."""
+    tracker.add(1.5)
+    tracker.reset()
+    assert tracker.max() == 0.0
+
+
+# ====================== p95() Tests ======================
+
+
+def test_p95_returns_zero_when_empty(tracker):
+    """Test p95() returns 0.0 when tracker is empty."""
+    assert tracker.p95() == 0.0
+
+
+def test_p95_returns_95th_percentile(tracker):
+    """Test p95() returns the 95th percentile."""
+    # Add 100 values
+    for i in range(100):
+        tracker.add(i / 100.0)
+
+    p95 = tracker.p95()
+    assert 0.93 <= p95 <= 0.96
+
+
+def test_p95_equals_percentile_95(tracker):
+    """Test p95() equals percentile(0.95)."""
+    for i in range(50):
+        tracker.add(i / 50.0)
+
+    assert tracker.p95() == tracker.percentile(0.95)
+
+
+# ====================== Edge Cases Tests ======================
+
+
+def test_single_value(tracker):
+    """Test tracker behavior with single value."""
+    tracker.add(0.75)
+
+    assert len(tracker) == 1
+    assert tracker.max() == 0.75
+    assert tracker.percentile(0.0) == 0.75
+    assert tracker.percentile(0.5) == 0.75
+    assert tracker.percentile(1.0) == 0.75
+
+
+def test_all_same_values(tracker):
+    """Test tracker with all identical values."""
+    for _ in range(10):
+        tracker.add(0.5)
+
+    assert len(tracker) == 10
+    assert tracker.max() == 0.5
+    assert tracker.percentile(0.0) == 0.5
+    assert tracker.percentile(0.5) == 0.5
+    assert tracker.percentile(1.0) == 0.5
+
+
+def test_very_small_values(tracker):
+    """Test tracker with very small float values."""
+    tracker.add(1e-10)
+    tracker.add(2e-10)
+    tracker.add(3e-10)
+
+    assert len(tracker) == 3
+    assert tracker.max() == pytest.approx(3e-10)
+
+
+def test_very_large_values(tracker):
+    """Test tracker with very large float values."""
+    tracker.add(1e10)
+    tracker.add(2e10)
+    tracker.add(3e10)
+
+    assert len(tracker) == 3
+    assert tracker.max() == pytest.approx(3e10)
+
+
+# ====================== Integration Tests ======================
+
+
+def test_typical_usage_pattern(tracker):
+    """Test a typical usage pattern of the tracker."""
+    # Simulate adding latencies over time
+    latencies = [0.05, 0.08, 0.12, 0.07, 0.15, 0.09, 0.11, 0.06, 0.14, 0.10]
+
+    for lat in latencies:
+        tracker.add(lat)
+
+    # Check statistics
+    assert len(tracker) == 10
+    assert tracker.max() == 0.15
+
+    # p95 should be close to max since we have only 10 values
+    p95 = tracker.p95()
+    assert p95 >= tracker.percentile(0.5)  # p95 should be >= median
+    assert p95 <= tracker.max()  # p95 should be <= max
+
+
+def test_reset_and_reuse(tracker):
+    """Test resetting and reusing tracker."""
+    # First batch
+    tracker.add(1.0)
+    tracker.add(2.0)
+    assert tracker.max() == 2.0
+
+    # Reset
+    tracker.reset()
+
+    # Second batch
+    tracker.add(0.5)
+    tracker.add(0.8)
+    assert len(tracker) == 2
+    assert tracker.max() == 0.8
+    assert tracker.percentile(0.5) <= 0.8
+
+
+# ====================== Type Conversion Tests ======================
+
+
+def test_add_with_integer(tracker):
+    """Test adding integer values."""
+    tracker.add(5)
+    assert len(tracker) == 1
+    assert tracker.max() == 5.0
+
+
+def test_add_with_string_number(tracker):
+    """Test adding string representation of number."""
+    tracker.add("3.14")
+    assert len(tracker) == 1
+    assert tracker.max() == pytest.approx(3.14)
+
+
+def test_percentile_converts_q_to_float(tracker):
+    """Test percentile converts q parameter to float."""
+    tracker.add(0.5)
+    tracker.add(0.8)
+
+    # Pass integer q
+    result = tracker.percentile(1)
+    assert result == 0.8

tests/policies/rtc/test_modeling_rtc.py

@@ -0,0 +1,773 @@
+#!/usr/bin/env python
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Tests for RTC modeling module (RTCProcessor)."""
+
+import pytest
+import torch
+
+from lerobot.configs.types import RTCAttentionSchedule
+from lerobot.policies.rtc.configuration_rtc import RTCConfig
+from lerobot.policies.rtc.modeling_rtc import RTCProcessor
+
+# ====================== Fixtures ======================
+
+
+@pytest.fixture
+def rtc_config_debug_enabled():
+    """Create RTC config with debug enabled."""
+    return RTCConfig(
+        enabled=True,
+        prefix_attention_schedule=RTCAttentionSchedule.LINEAR,
+        max_guidance_weight=10.0,
+        execution_horizon=10,
+        debug=True,
+        debug_maxlen=100,
+    )
+
+
+@pytest.fixture
+def rtc_config_debug_disabled():
+    """Create RTC config with debug disabled."""
+    return RTCConfig(
+        enabled=True,
+        prefix_attention_schedule=RTCAttentionSchedule.LINEAR,
+        max_guidance_weight=10.0,
+        execution_horizon=10,
+        debug=False,
+    )
+
+
+@pytest.fixture
+def rtc_processor_debug_enabled(rtc_config_debug_enabled):
+    """Create RTCProcessor with debug enabled."""
+    return RTCProcessor(rtc_config_debug_enabled)
+
+
+@pytest.fixture
+def rtc_processor_debug_disabled(rtc_config_debug_disabled):
+    """Create RTCProcessor with debug disabled."""
+    return RTCProcessor(rtc_config_debug_disabled)
+
+
+@pytest.fixture
+def sample_x_t():
+    """Create sample x_t tensor (batch, time, action_dim)."""
+    return torch.randn(1, 50, 6)
+
+
+@pytest.fixture
+def sample_prev_chunk():
+    """Create sample previous chunk tensor."""
+    return torch.randn(1, 50, 6)
+
+
+# ====================== Initialization Tests ======================
+
+
+def test_rtc_processor_initialization_with_debug(rtc_config_debug_enabled):
+    """Test RTCProcessor initializes with debug tracker."""
+    processor = RTCProcessor(rtc_config_debug_enabled)
+    assert processor.rtc_config == rtc_config_debug_enabled
+    assert processor.tracker is not None
+    assert processor.tracker.enabled is True
+
+
+def test_rtc_processor_initialization_without_debug(rtc_config_debug_disabled):
+    """Test RTCProcessor initializes without debug tracker."""
+    processor = RTCProcessor(rtc_config_debug_disabled)
+    assert processor.rtc_config == rtc_config_debug_disabled
+    assert processor.tracker is None
+
+
+# ====================== Tracker Proxy Methods Tests ======================
+
+
+def test_track_when_tracker_enabled(rtc_processor_debug_enabled, sample_x_t):
+    """Test track() forwards to tracker when enabled."""
+    rtc_processor_debug_enabled.track(
+        time=torch.tensor(0.5),
+        x_t=sample_x_t,
+        v_t=sample_x_t,
+        guidance_weight=2.0,
+    )
+
+    # Should have tracked one step
+    steps = rtc_processor_debug_enabled.get_all_debug_steps()
+    assert len(steps) == 1
+    assert steps[0].time == 0.5
+
+
+def test_track_when_tracker_disabled(rtc_processor_debug_disabled, sample_x_t):
+    """Test track() does nothing when tracker disabled."""
+    # Should not raise error
+    rtc_processor_debug_disabled.track(
+        time=torch.tensor(0.5),
+        x_t=sample_x_t,
+        v_t=sample_x_t,
+    )
+
+    # Should return empty list
+    steps = rtc_processor_debug_disabled.get_all_debug_steps()
+    assert len(steps) == 0
+
+
+def test_get_all_debug_steps_when_enabled(rtc_processor_debug_enabled, sample_x_t):
+    """Test get_all_debug_steps() returns tracked steps."""
+    rtc_processor_debug_enabled.track(time=torch.tensor(0.5), x_t=sample_x_t)
+    rtc_processor_debug_enabled.track(time=torch.tensor(0.4), x_t=sample_x_t)
+
+    steps = rtc_processor_debug_enabled.get_all_debug_steps()
+    assert len(steps) == 2
+
+
+def test_get_all_debug_steps_when_disabled(rtc_processor_debug_disabled):
+    """Test get_all_debug_steps() returns empty list when disabled."""
+    steps = rtc_processor_debug_disabled.get_all_debug_steps()
+    assert steps == []
+    assert isinstance(steps, list)
+
+
+def test_is_debug_enabled_when_tracker_exists(rtc_processor_debug_enabled):
+    """Test is_debug_enabled() returns True when tracker enabled."""
+    assert rtc_processor_debug_enabled.is_debug_enabled() is True
+
+
+def test_is_debug_enabled_when_tracker_disabled(rtc_processor_debug_disabled):
+    """Test is_debug_enabled() returns False when tracker disabled."""
+    assert rtc_processor_debug_disabled.is_debug_enabled() is False
+
+
+def test_reset_tracker_when_enabled(rtc_processor_debug_enabled, sample_x_t):
+    """Test reset_tracker() clears tracked steps."""
+    rtc_processor_debug_enabled.track(time=torch.tensor(0.5), x_t=sample_x_t)
+    rtc_processor_debug_enabled.track(time=torch.tensor(0.4), x_t=sample_x_t)
+    assert len(rtc_processor_debug_enabled.get_all_debug_steps()) == 2
+
+    rtc_processor_debug_enabled.reset_tracker()
+    assert len(rtc_processor_debug_enabled.get_all_debug_steps()) == 0
+
+
+def test_reset_tracker_when_disabled(rtc_processor_debug_disabled):
+    """Test reset_tracker() doesn't error when tracker disabled."""
+    rtc_processor_debug_disabled.reset_tracker()  # Should not raise
+
+
+# ====================== get_prefix_weights Tests ======================
+
+
+def test_get_prefix_weights_zeros_schedule():
+    """Test get_prefix_weights with ZEROS schedule."""
+    config = RTCConfig(prefix_attention_schedule=RTCAttentionSchedule.ZEROS)
+    processor = RTCProcessor(config)
+
+    weights = processor.get_prefix_weights(start=5, end=10, total=20)
+
+    # First 5 should be 1.0, rest should be 0.0
+    assert weights.shape == (20,)
+    assert torch.all(weights[:5] == 1.0)
+    assert torch.all(weights[5:] == 0.0)
+
+
+def test_get_prefix_weights_ones_schedule():
+    """Test get_prefix_weights with ONES schedule."""
+    config = RTCConfig(prefix_attention_schedule=RTCAttentionSchedule.ONES)
+    processor = RTCProcessor(config)
+
+    weights = processor.get_prefix_weights(start=5, end=15, total=20)
+
+    # First 15 should be 1.0, rest should be 0.0
+    assert weights.shape == (20,)
+    assert torch.all(weights[:15] == 1.0)
+    assert torch.all(weights[15:] == 0.0)
+
+
+def test_get_prefix_weights_linear_schedule():
+    """Test get_prefix_weights with LINEAR schedule."""
+    config = RTCConfig(prefix_attention_schedule=RTCAttentionSchedule.LINEAR)
+    processor = RTCProcessor(config)
+
+    weights = processor.get_prefix_weights(start=5, end=14, total=25)
+
+    # Should have shape (20,)
+    assert weights.shape == (25,)
+
+    # First 5 should be 1.0 (leading ones)
+    assert torch.all(weights[:5] == 1.0)
+
+    # Middle section (5:15) should be linearly decreasing from 1 to 0
+    middle_weights = torch.tensor([0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1])
+    assert torch.allclose(weights[5:14], middle_weights)
+
+    # Last 5 should be 0.0 (trailing zeros)
+    assert torch.all(weights[14:] == 0.0)
+
+
+def test_get_prefix_weights_exp_schedule():
+    """Test get_prefix_weights with EXP schedule."""
+    config = RTCConfig(prefix_attention_schedule=RTCAttentionSchedule.EXP)
+    processor = RTCProcessor(config)
+
+    weights = processor.get_prefix_weights(start=5, end=14, total=25)
+
+    # Should have shape (20,)
+    assert weights.shape == (25,)
+
+    # First 5 should be 1.0 (leading ones)
+    assert torch.all(weights[:5] == 1.0)
+
+    # Middle section should be exponentially weighted
+    middle_weights = torch.tensor([0.7645, 0.5706, 0.4130, 0.2871, 0.1888, 0.1145, 0.0611, 0.0258, 0.0061])
+    assert torch.allclose(weights[5:14], middle_weights, atol=1e-4)
+
+    # Last 5 should be 0.0 (trailing zeros)
+    assert torch.all(weights[14:] == 0.0)
+
+
+def test_get_prefix_weights_with_start_equals_end():
+    """Test get_prefix_weights when start equals end."""
+    config = RTCConfig(prefix_attention_schedule=RTCAttentionSchedule.LINEAR)
+    processor = RTCProcessor(config)
+
+    weights = processor.get_prefix_weights(start=10, end=10, total=20)
+
+    # Should have ones up to start, then zeros
+    assert torch.all(weights[:10] == 1.0)
+    assert torch.all(weights[10:] == 0.0)
+
+
+def test_get_prefix_weights_with_start_greater_than_end():
+    """Test get_prefix_weights when start > end (gets clamped)."""
+    config = RTCConfig(prefix_attention_schedule=RTCAttentionSchedule.LINEAR)
+    processor = RTCProcessor(config)
+
+    # start > end should use min(start, end) = end
+    weights = processor.get_prefix_weights(start=15, end=10, total=20)
+
+    # Should have ones up to end (10), then zeros
+    assert torch.all(weights[:10] == 1.0)
+    assert torch.all(weights[10:] == 0.0)
+
+
+# ====================== Helper Method Tests ======================
+
+
+def test_linweights_with_end_equals_start():
+    """Test _linweights when end equals start."""
+    config = RTCConfig()
+    processor = RTCProcessor(config)
+
+    weights = processor._linweights(start=10, end=10, total=20)
+
+    # Should return empty tensor
+    assert len(weights) == 0
+
+
+def test_linweights_with_end_less_than_start():
+    """Test _linweights when end < start."""
+    config = RTCConfig()
+    processor = RTCProcessor(config)
+
+    weights = processor._linweights(start=15, end=10, total=20)
+
+    # Should return empty tensor
+    assert len(weights) == 0
+
+
+def test_add_trailing_zeros_normal():
+    """Test _add_trailing_zeros adds zeros correctly."""
+    config = RTCConfig()
+    processor = RTCProcessor(config)
+
+    weights = torch.tensor([1.0, 0.8, 0.6, 0.4, 0.2])
+    result = processor._add_trailing_zeros(weights, total=10, end=5)
+
+    # Should add 5 zeros (total - end = 10 - 5 = 5)
+    assert len(result) == 10
+    assert torch.all(result[:5] == weights)
+    assert torch.all(result[5:] == 0.0)
+
+
+def test_add_trailing_zeros_no_zeros_needed():
+    """Test _add_trailing_zeros when no zeros needed."""
+    config = RTCConfig()
+    processor = RTCProcessor(config)
+
+    weights = torch.tensor([1.0, 0.8, 0.6])
+    result = processor._add_trailing_zeros(weights, total=3, end=5)
+
+    # zeros_len = 3 - 5 = -2 <= 0, so no zeros added
+    assert torch.equal(result, weights)
+
+
+def test_add_leading_ones_normal():
+    """Test _add_leading_ones adds ones correctly."""
+    config = RTCConfig()
+    processor = RTCProcessor(config)
+
+    weights = torch.tensor([0.8, 0.6, 0.4, 0.2, 0.0])
+    result = processor._add_leading_ones(weights, start=3, total=10)
+
+    # Should add 3 ones at the start
+    assert len(result) == 8
+    assert torch.all(result[:3] == 1.0)
+    assert torch.all(result[3:] == weights)
+
+
+def test_add_leading_ones_no_ones_needed():
+    """Test _add_leading_ones when no ones needed."""
+    config = RTCConfig()
+    processor = RTCProcessor(config)
+
+    weights = torch.tensor([0.8, 0.6, 0.4])
+    result = processor._add_leading_ones(weights, start=0, total=10)
+
+    # ones_len = 0, so no ones added
+    assert torch.equal(result, weights)
+
+
+def test_get_prefix_weights_with_start_equals_total():
+    """Test get_prefix_weights when start equals total."""
+    config = RTCConfig(prefix_attention_schedule=RTCAttentionSchedule.LINEAR)
+    processor = RTCProcessor(config)
+
+    weights = processor.get_prefix_weights(start=10, end=10, total=20)
+
+    # Should have ones up to start, then zeros
+    assert len(weights) == 20
+    assert torch.all(weights[:10] == 1.0)
+    assert torch.all(weights[10:] == 0.0)
+
+
+def test_get_prefix_weights_with_total_less_than_start():
+    """Test get_prefix_weights when total less than start."""
+    config = RTCConfig(prefix_attention_schedule=RTCAttentionSchedule.LINEAR)
+    processor = RTCProcessor(config)
+
+    weights = processor.get_prefix_weights(start=10, end=10, total=5)
+
+    # Should have ones up to start, then zeros
+    assert len(weights) == 5
+    assert torch.all(weights == 1.0)
+
+
+# ====================== denoise_step Tests ======================
+
+
+def test_denoise_step_without_prev_chunk(rtc_processor_debug_disabled):
+    """Test denoise_step without previous chunk (no guidance)."""
+    x_t = torch.randn(1, 50, 6)
+
+    # Mock denoiser that returns fixed velocity
+    def mock_denoiser(x):
+        return torch.ones_like(x) * 0.5
+
+    result = rtc_processor_debug_disabled.denoise_step(
+        x_t=x_t,
+        prev_chunk_left_over=None,
+        inference_delay=5,
+        time=torch.tensor(0.5),
+        original_denoise_step_partial=mock_denoiser,
+    )
+
+    # Should return v_t unchanged (no guidance)
+    expected = mock_denoiser(x_t)
+    assert torch.allclose(result, expected)
+
+
+def test_denoise_step_with_prev_chunk(rtc_processor_debug_disabled):
+    """Test denoise_step with previous chunk applies guidance."""
+    x_t = torch.ones(1, 20, 1)
+    prev_chunk = torch.full((1, 20, 1), 0.1)
+
+    def mock_denoiser(x):
+        return x * 0.5
+
+    result = rtc_processor_debug_disabled.denoise_step(
+        x_t=x_t,
+        prev_chunk_left_over=prev_chunk,
+        inference_delay=5,
+        time=torch.tensor(0.5),
+        original_denoise_step_partial=mock_denoiser,
+    )
+
+    expected_result = torch.tensor(
+        [
+            [
+                [1.8000],
+                [1.8000],
+                [1.8000],
+                [1.8000],
+                [1.8000],
+                [1.5833],
+                [1.3667],
+                [1.1500],
+                [0.9333],
+                [0.7167],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+            ]
+        ]
+    )
+
+    assert torch.allclose(result, expected_result, atol=1e-4)
+
+
+def test_denoise_step_adds_batch_dimension():
+    """Test denoise_step handles 2D input by adding batch dimension."""
+    config = RTCConfig(execution_horizon=10, max_guidance_weight=5.0)
+    processor = RTCProcessor(config)
+
+    # 2D input (no batch dimension)
+    x_t = torch.randn(10, 6)
+    prev_chunk = torch.randn(5, 6)
+
+    def mock_denoiser(x):
+        return x * 0.5
+
+    result = processor.denoise_step(
+        x_t=x_t,
+        prev_chunk_left_over=prev_chunk,
+        inference_delay=5,
+        time=torch.tensor(0.5),
+        original_denoise_step_partial=mock_denoiser,
+    )
+
+    # Output should be 2D (batch dimension removed)
+    assert result.ndim == 2
+    assert result.shape == (10, 6)
+
+
+def test_denoise_step_uses_custom_execution_horizon():
+    """Test denoise_step uses custom execution_horizon parameter."""
+    config = RTCConfig(execution_horizon=10)
+    processor = RTCProcessor(config)
+
+    x_t = torch.ones(1, 20, 1)
+    prev_chunk = torch.full((1, 15, 1), 0.1)
+
+    def mock_denoiser(x):
+        return x * 0.5
+
+    result = processor.denoise_step(
+        x_t=x_t,
+        prev_chunk_left_over=prev_chunk,
+        inference_delay=5,
+        time=torch.tensor(0.5),
+        original_denoise_step_partial=mock_denoiser,
+        execution_horizon=15,
+    )
+
+    expected_result = torch.tensor(
+        [
+            [
+                [1.8000],
+                [1.8000],
+                [1.8000],
+                [1.8000],
+                [1.8000],
+                [1.6818],
+                [1.5636],
+                [1.4455],
+                [1.3273],
+                [1.2091],
+                [1.0909],
+                [0.9727],
+                [0.8545],
+                [0.7364],
+                [0.6182],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+            ]
+        ]
+    )
+
+    assert torch.allclose(result, expected_result, atol=1e-4)
+
+
+def test_denoise_step_guidance_weight_at_time_zero():
+    """Test denoise_step handles time=0 (tau=1) without NaN/Inf."""
+    config = RTCConfig(max_guidance_weight=10.0)
+    processor = RTCProcessor(config)
+
+    x_t = torch.ones(1, 20, 1)
+    prev_chunk = torch.full((1, 20, 1), 0.1)
+
+    def mock_denoiser(x):
+        return x * 0.5
+
+    result = processor.denoise_step(
+        x_t=x_t,
+        prev_chunk_left_over=prev_chunk,
+        inference_delay=5,
+        time=torch.tensor(0.0),
+        original_denoise_step_partial=mock_denoiser,
+    )
+
+    expected_result = torch.tensor(
+        [
+            [
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+                [0.5000],
+            ]
+        ]
+    )
+
+    assert torch.allclose(result, expected_result, atol=1e-4)
+
+
+def test_denoise_step_with_real_denoise_step_partial():
+    """Test denoise_step with a real denoiser."""
+    config = RTCConfig(max_guidance_weight=10.0)
+    processor = RTCProcessor(config)
+
+    batch_size = 10
+    action_dim = 6
+    chunk_size = 20
+
+    x_t = torch.ones(batch_size, chunk_size, action_dim)
+    prev_chunk = torch.full((batch_size, chunk_size, action_dim), 0.1)
+
+    velocity_function = torch.nn.Sequential(
+        torch.nn.Linear(action_dim, 1000),
+        torch.nn.ReLU(),
+        torch.nn.Linear(1000, 256),
+        torch.nn.ReLU(),
+        torch.nn.Linear(256, action_dim),
+    )
+
+    def mock_denoiser(x):
+        return velocity_function(x)
+
+    result = processor.denoise_step(
+        x_t=x_t,
+        prev_chunk_left_over=prev_chunk,
+        inference_delay=5,
+        time=torch.tensor(0.5),
+        original_denoise_step_partial=mock_denoiser,
+    )
+
+    assert result.shape == (batch_size, chunk_size, action_dim)
+
+
+def test_denoise_step_guidance_weight_at_time_one():
+    """Test denoise_step handles time=1 (tau=0) with max_guidance_weight clamping."""
+    config = RTCConfig(max_guidance_weight=10.0)
+    processor = RTCProcessor(config)
+
+    x_t = torch.randn(1, 50, 6)
+    prev_chunk = torch.randn(1, 50, 6)
+
+    def mock_denoiser(x):
+        return torch.ones_like(x) * 0.5
+
+    # Time = 1 => tau = 0, c = (1-tau)/tau = 1/0 = inf (clamped to max_guidance_weight)
+    result = processor.denoise_step(
+        x_t=x_t,
+        prev_chunk_left_over=prev_chunk,
+        inference_delay=5,
+        time=torch.tensor(1.0),
+        original_denoise_step_partial=mock_denoiser,
+    )
+
+    # Should clamp to max_guidance_weight (no Inf)
+    assert not torch.any(torch.isinf(result))
+
+
+def test_denoise_step_tracks_debug_info(rtc_processor_debug_enabled):
+    """Test denoise_step tracks debug information when enabled."""
+    x_t = torch.randn(1, 50, 6)
+    prev_chunk = torch.randn(1, 50, 6)
+
+    def mock_denoiser(x):
+        return torch.ones_like(x) * 0.5
+
+    rtc_processor_debug_enabled.denoise_step(
+        x_t=x_t,
+        prev_chunk_left_over=prev_chunk,
+        inference_delay=5,
+        time=torch.tensor(0.5),
+        original_denoise_step_partial=mock_denoiser,
+    )
+
+    # Should have tracked one step
+    steps = rtc_processor_debug_enabled.get_all_debug_steps()
+    assert len(steps) == 1
+
+    # Check tracked values
+    step = steps[0]
+    assert step.time == 0.5
+    assert step.x1_t is not None
+    assert step.correction is not None
+    assert step.err is not None
+    assert step.weights is not None
+    assert step.guidance_weight is not None
+    assert step.inference_delay == 5
+
+
+def test_denoise_step_doesnt_track_without_debug(rtc_processor_debug_disabled):
+    """Test denoise_step doesn't track when debug disabled."""
+    x_t = torch.randn(1, 50, 6)
+    prev_chunk = torch.randn(1, 50, 6)
+
+    def mock_denoiser(x):
+        return torch.ones_like(x) * 0.5
+
+    rtc_processor_debug_disabled.denoise_step(
+        x_t=x_t,
+        prev_chunk_left_over=prev_chunk,
+        inference_delay=5,
+        time=torch.tensor(0.5),
+        original_denoise_step_partial=mock_denoiser,
+    )
+
+    # Should not track
+    steps = rtc_processor_debug_disabled.get_all_debug_steps()
+    assert len(steps) == 0
+
+
+# ====================== Integration Tests ======================
+
+
+def test_denoise_step_full_workflow():
+    """Test complete denoise_step workflow."""
+    config = RTCConfig(
+        enabled=True,
+        prefix_attention_schedule=RTCAttentionSchedule.LINEAR,
+        max_guidance_weight=5.0,
+        execution_horizon=10,
+        debug=True,
+    )
+    processor = RTCProcessor(config)
+
+    # Simulate two denoising steps
+    x_t1 = torch.randn(1, 50, 6)
+    x_t2 = torch.randn(1, 50, 6)
+
+    def mock_denoiser(x):
+        return torch.randn_like(x) * 0.1
+
+    # First step - no guidance
+    result1 = processor.denoise_step(
+        x_t=x_t1,
+        prev_chunk_left_over=None,
+        inference_delay=5,
+        time=torch.tensor(0.8),
+        original_denoise_step_partial=mock_denoiser,
+    )
+
+    # Second step - with guidance
+    result2 = processor.denoise_step(
+        x_t=x_t2,
+        prev_chunk_left_over=result1,
+        inference_delay=5,
+        time=torch.tensor(0.6),
+        original_denoise_step_partial=mock_denoiser,
+    )
+
+    # Both should complete successfully
+    assert result1.shape == (1, 50, 6)
+    assert result2.shape == (1, 50, 6)
+
+    # Should have tracked one step (second one, first had no prev_chunk)
+    steps = processor.get_all_debug_steps()
+    assert len(steps) == 1
+
+
+@pytest.mark.skipif(not torch.cuda.is_available(), reason="CUDA not available")
+def test_denoise_step_with_cuda_tensors():
+    """Test denoise_step works with CUDA tensors."""
+    config = RTCConfig(execution_horizon=10, max_guidance_weight=5.0)
+    processor = RTCProcessor(config)
+
+    x_t = torch.randn(1, 50, 6, device="cuda")
+    prev_chunk = torch.randn(1, 50, 6, device="cuda")
+
+    def mock_denoiser(x):
+        return torch.ones_like(x) * 0.5
+
+    result = processor.denoise_step(
+        x_t=x_t,
+        prev_chunk_left_over=prev_chunk,
+        inference_delay=5,
+        time=torch.tensor(0.5),
+        original_denoise_step_partial=mock_denoiser,
+    )
+
+    # Result should be on CUDA
+    assert result.device.type == "cuda"
+    assert result.shape == x_t.shape
+
+
+def test_denoise_step_deterministic_with_same_inputs():
+    """Test denoise_step produces same output with same inputs."""
+    config = RTCConfig(execution_horizon=10, max_guidance_weight=5.0)
+    processor = RTCProcessor(config)
+
+    torch.manual_seed(42)
+    x_t = torch.randn(1, 50, 6)
+    prev_chunk = torch.randn(1, 50, 6)
+
+    def deterministic_denoiser(x):
+        return torch.ones_like(x) * 0.5
+
+    result1 = processor.denoise_step(
+        x_t=x_t.clone(),
+        prev_chunk_left_over=prev_chunk.clone(),
+        inference_delay=5,
+        time=torch.tensor(0.5),
+        original_denoise_step_partial=deterministic_denoiser,
+    )
+
+    result2 = processor.denoise_step(
+        x_t=x_t.clone(),
+        prev_chunk_left_over=prev_chunk.clone(),
+        inference_delay=5,
+        time=torch.tensor(0.5),
+        original_denoise_step_partial=deterministic_denoiser,
+    )
+
+    # Should produce identical results
+    assert torch.allclose(result1, result2)

tests/policies/smolvla/test_smolvla_rtc.py

@@ -0,0 +1,323 @@
+#!/usr/bin/env python
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Test SmolVLA policy with Real-Time Chunking (RTC) enabled during inference."""
+
+import pytest
+import torch
+
+from lerobot.configs.types import FeatureType, PolicyFeature, RTCAttentionSchedule  # noqa: E402
+from lerobot.policies.factory import make_pre_post_processors  # noqa: E402
+from lerobot.policies.rtc.configuration_rtc import RTCConfig  # noqa: E402
+from lerobot.policies.smolvla.configuration_smolvla import SmolVLAConfig  # noqa: F401
+from lerobot.utils.random_utils import set_seed  # noqa: E402
+from tests.utils import require_cuda, require_package  # noqa: E402
+
+
+@require_package("transformers")
+@require_cuda
+def test_smolvla_rtc_initialization():
+    from lerobot.policies.smolvla.modeling_smolvla import SmolVLAPolicy  # noqa: F401
+
+    """Test SmolVLA policy can initialize RTC processor."""
+    set_seed(42)
+
+    config = SmolVLAConfig(max_action_dim=7, chunk_size=50)
+
+    # Add RTC config
+    config.rtc_config = RTCConfig(
+        enabled=True,
+        execution_horizon=10,
+        max_guidance_weight=5.0,
+        prefix_attention_schedule=RTCAttentionSchedule.EXP,
+        debug=False,
+    )
+
+    config.input_features = {
+        "observation.state": PolicyFeature(type=FeatureType.STATE, shape=(14,)),
+        "observation.images.base_0_rgb": PolicyFeature(type=FeatureType.VISUAL, shape=(3, 224, 224)),
+    }
+    config.output_features = {
+        "action": PolicyFeature(type=FeatureType.ACTION, shape=(7,)),
+    }
+
+    # Instantiate policy
+    policy = SmolVLAPolicy(config)
+
+    # Verify RTC processor is initialized
+    assert hasattr(policy, "rtc_processor")
+    assert policy.rtc_processor is not None
+    assert policy.rtc_processor.rtc_config.enabled is True
+
+    print("✓ SmolVLA RTC initialization: Test passed")
+
+
+@require_package("transformers")
+@require_cuda
+def test_smolvla_rtc_initialization_without_rtc_config():
+    from lerobot.policies.smolvla.modeling_smolvla import SmolVLAPolicy  # noqa: F401
+
+    """Test SmolVLA policy can initialize without RTC config."""
+    set_seed(42)
+
+    config = SmolVLAConfig(max_action_dim=7, chunk_size=50)
+
+    # Instantiate policy
+    policy = SmolVLAPolicy(config)
+
+    # Verify RTC processor is not initialized
+    assert hasattr(policy, "rtc_processor")
+    assert policy.rtc_processor is None
+    assert policy.model.rtc_processor is None
+    assert policy._rtc_enabled() is False
+
+    print("✓ SmolVLA RTC initialization without RTC config: Test passed")
+
+
+@require_package("transformers")
+@require_cuda
+@pytest.mark.skipif(True, reason="Requires pretrained SmolVLA model weights")
+def test_smolvla_rtc_inference_with_prev_chunk():
+    from lerobot.policies.smolvla.modeling_smolvla import SmolVLAPolicy  # noqa: F401
+
+    """Test SmolVLA policy inference with RTC and previous chunk."""
+    set_seed(42)
+
+    config = SmolVLAConfig(max_action_dim=7, chunk_size=50)
+
+    # Add RTC config
+    config.rtc_config = RTCConfig(
+        enabled=True,
+        execution_horizon=10,
+        max_guidance_weight=5.0,
+        prefix_attention_schedule=RTCAttentionSchedule.EXP,
+        debug=False,
+    )
+
+    config.input_features = {
+        "observation.state": PolicyFeature(type=FeatureType.STATE, shape=(14,)),
+        "observation.images.base_0_rgb": PolicyFeature(type=FeatureType.VISUAL, shape=(3, 224, 224)),
+    }
+    config.output_features = {
+        "action": PolicyFeature(type=FeatureType.ACTION, shape=(7,)),
+    }
+
+    # Create dataset stats
+    dataset_stats = {
+        "observation.state": {"mean": torch.zeros(14), "std": torch.ones(14)},
+        "action": {"mean": torch.zeros(7), "std": torch.ones(7)},
+        "observation.images.base_0_rgb": {"mean": torch.zeros(3, 224, 224), "std": torch.ones(3, 224, 224)},
+    }
+
+    # Instantiate policy and create preprocessor
+    policy = SmolVLAPolicy(config)
+    policy.eval()
+    preprocessor, _ = make_pre_post_processors(
+        policy_cfg=config, pretrained_path=None, dataset_stats=dataset_stats
+    )
+
+    device = config.device
+
+    # Create dummy batch
+    batch = {
+        "observation.state": torch.randn(1, 14, dtype=torch.float32, device=device),
+        "observation.images.base_0_rgb": torch.rand(1, 3, 224, 224, dtype=torch.float32, device=device),
+        "task": ["Pick up the object"],
+    }
+    batch = preprocessor(batch)
+
+    # Create previous chunk
+    prev_chunk = torch.randn(1, 25, 7, dtype=torch.float32, device=device)
+
+    with torch.no_grad():
+        # Use same noise for fair comparison
+        noise = policy.model.sample_noise((1, config.chunk_size, 7), device)
+
+        # Test with RTC and previous chunk
+        actions_with_rtc = policy.predict_action_chunk(
+            batch,
+            noise=noise.clone(),
+            prev_chunk_left_over=prev_chunk,
+            inference_delay=4,
+            execution_horizon=10,
+        )
+
+        # Test without RTC for comparison
+        policy.config.rtc_config.enabled = False
+        actions_without_rtc = policy.predict_action_chunk(batch, noise=noise.clone())
+        policy.config.rtc_config.enabled = True
+
+    # Verify shapes
+    assert actions_with_rtc.shape == (1, config.chunk_size, 7)
+    assert actions_without_rtc.shape == (1, config.chunk_size, 7)
+
+    # With previous chunk, actions should be different (RTC guidance applied)
+    assert not torch.allclose(actions_with_rtc, actions_without_rtc, rtol=1e-3)
+
+    print("✓ SmolVLA RTC inference with prev_chunk: Test passed")
+
+
+@require_package("transformers")
+@require_cuda
+@pytest.mark.skipif(True, reason="Requires pretrained SmolVLA model weights")
+def test_smolvla_rtc_inference_without_prev_chunk():
+    from lerobot.policies.smolvla.modeling_smolvla import SmolVLAPolicy  # noqa: F401
+
+    """Test SmolVLA policy inference with RTC but no previous chunk (RTC should have no effect)."""
+    set_seed(42)
+
+    config = SmolVLAConfig(max_action_dim=7, chunk_size=50)
+
+    # Add RTC config
+    config.rtc_config = RTCConfig(
+        enabled=True,
+        execution_horizon=10,
+        max_guidance_weight=5.0,
+        prefix_attention_schedule=RTCAttentionSchedule.EXP,
+        debug=False,
+    )
+
+    config.input_features = {
+        "observation.state": PolicyFeature(type=FeatureType.STATE, shape=(14,)),
+        "observation.images.base_0_rgb": PolicyFeature(type=FeatureType.VISUAL, shape=(3, 224, 224)),
+    }
+    config.output_features = {
+        "action": PolicyFeature(type=FeatureType.ACTION, shape=(7,)),
+    }
+
+    # Create dataset stats
+    dataset_stats = {
+        "observation.state": {"mean": torch.zeros(14), "std": torch.ones(14)},
+        "action": {"mean": torch.zeros(7), "std": torch.ones(7)},
+        "observation.images.base_0_rgb": {"mean": torch.zeros(3, 224, 224), "std": torch.ones(3, 224, 224)},
+    }
+
+    # Instantiate policy and create preprocessor
+    policy = SmolVLAPolicy(config)
+    policy.eval()
+    preprocessor, _ = make_pre_post_processors(
+        policy_cfg=config, pretrained_path=None, dataset_stats=dataset_stats
+    )
+
+    device = config.device
+
+    # Create dummy batch
+    batch = {
+        "observation.state": torch.randn(1, 14, dtype=torch.float32, device=device),
+        "observation.images.base_0_rgb": torch.rand(1, 3, 224, 224, dtype=torch.float32, device=device),
+        "task": ["Pick up the object"],
+    }
+    batch = preprocessor(batch)
+
+    with torch.no_grad():
+        # Use same noise for fair comparison
+        noise = policy.model.sample_noise((1, config.chunk_size, 7), device)
+
+        # Test with RTC enabled but no previous chunk
+        actions_with_rtc_no_prev = policy.predict_action_chunk(
+            batch,
+            noise=noise.clone(),
+            prev_chunk_left_over=None,
+        )
+
+        # Test without RTC
+        policy.config.rtc_config.enabled = False
+        actions_without_rtc = policy.predict_action_chunk(batch, noise=noise.clone())
+        policy.config.rtc_config.enabled = True
+
+    # Without previous chunk, RTC should have no effect
+    assert torch.allclose(actions_with_rtc_no_prev, actions_without_rtc, rtol=1e-5)
+
+    print("✓ SmolVLA RTC inference without prev_chunk: Test passed")
+
+
+@require_package("transformers")
+@require_cuda
+@pytest.mark.skipif(True, reason="Requires pretrained SmolVLA model weights")
+def test_smolvla_rtc_validation_rules():
+    from lerobot.policies.smolvla.modeling_smolvla import SmolVLAPolicy  # noqa: F401
+
+    """Test SmolVLA policy with RTC follows all three validation rules."""
+    set_seed(42)
+
+    config = SmolVLAConfig(max_action_dim=7, chunk_size=50)
+
+    # Add RTC config
+    config.rtc_config = RTCConfig(
+        enabled=True,
+        execution_horizon=10,
+        max_guidance_weight=5.0,
+        prefix_attention_schedule=RTCAttentionSchedule.EXP,
+        debug=False,
+    )
+
+    config.input_features = {
+        "observation.state": PolicyFeature(type=FeatureType.STATE, shape=(14,)),
+        "observation.images.base_0_rgb": PolicyFeature(type=FeatureType.VISUAL, shape=(3, 224, 224)),
+    }
+    config.output_features = {
+        "action": PolicyFeature(type=FeatureType.ACTION, shape=(7,)),
+    }
+
+    # Create dataset stats
+    dataset_stats = {
+        "observation.state": {"mean": torch.zeros(14), "std": torch.ones(14)},
+        "action": {"mean": torch.zeros(7), "std": torch.ones(7)},
+        "observation.images.base_0_rgb": {"mean": torch.zeros(3, 224, 224), "std": torch.ones(3, 224, 224)},
+    }
+
+    # Instantiate policy and create preprocessor
+    policy = SmolVLAPolicy(config)
+    policy.eval()
+    preprocessor, _ = make_pre_post_processors(
+        policy_cfg=config, pretrained_path=None, dataset_stats=dataset_stats
+    )
+
+    device = config.device
+
+    # Create dummy batch
+    batch = {
+        "observation.state": torch.randn(1, 14, dtype=torch.float32, device=device),
+        "observation.images.base_0_rgb": torch.rand(1, 3, 224, 224, dtype=torch.float32, device=device),
+        "task": ["Pick up the object"],
+    }
+    batch = preprocessor(batch)
+
+    # Create previous chunk
+    prev_chunk = torch.randn(1, 25, 7, dtype=torch.float32, device=device)
+
+    inference_delay = 4
+    execution_horizon = 10
+
+    with torch.no_grad():
+        # Use same noise for fair comparison
+        noise = policy.model.sample_noise((1, config.chunk_size, 7), device)
+
+        # Test with RTC
+        actions_with_rtc = policy.predict_action_chunk(
+            batch,
+            noise=noise.clone(),
+            prev_chunk_left_over=prev_chunk,
+            inference_delay=inference_delay,
+            execution_horizon=execution_horizon,
+        )
+
+        # Test without RTC
+        policy.config.rtc_config.enabled = False
+        actions_without_rtc = policy.predict_action_chunk(batch, noise=noise.clone())
+        policy.config.rtc_config.enabled = True
+
+    assert not torch.allclose(actions_with_rtc, actions_without_rtc, rtol=1e-3)