Add RTCConfig field to SmolVLAConfig

Add rtc_config as an optional field in SmolVLAConfig to properly
support Real-Time Chunking configuration. This replaces the previous
getattr() workarounds with direct attribute access, making the code
cleaner and more maintainable.

Changes:
- Import RTCConfig in configuration_smolvla.py
- Add rtc_config: RTCConfig | None = None field
- Revert getattr() calls to direct attribute access in modeling_smolvla.py

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Alexander Soare <alexander.soare159@gmail.com>
Co-Authored-By: Claude <noreply@anthropic.com>

src/lerobot/policies/smolvla/configuration_smolvla.py

@@ -20,6 +20,7 @@ from lerobot.optim.optimizers import AdamWConfig
 from lerobot.optim.schedulers import (
     CosineDecayWithWarmupSchedulerConfig,
 )
+from lerobot.policies.rtc.configuration_rtc import RTCConfig
 from lerobot.utils.constants import OBS_IMAGES
 
 
@@ -102,6 +103,9 @@ class SmolVLAConfig(PreTrainedConfig):
     min_period: float = 4e-3  # sensitivity range for the timestep used in sine-cosine positional encoding
     max_period: float = 4.0
 
+    # Real-Time Chunking (RTC) configuration
+    rtc_config: RTCConfig | None = None
+
     def __post_init__(self):
         super().__post_init__()
 

src/lerobot/policies/smolvla/modeling_smolvla.py

@@ -257,9 +257,8 @@ class SmolVLAPolicy(PreTrainedPolicy):
         """
         self.rtc_processor = None
 
-        rtc_config = getattr(self.config, "rtc_config", None)
-        if rtc_config is not None and rtc_config.enabled:
-            self.rtc_processor = RTCProcessor(rtc_config)
+        if self.config.rtc_config is not None and self.config.rtc_config.enabled:
+            self.rtc_processor = RTCProcessor(self.config.rtc_config)
 
             # In case of calling init_rtc_processor after the model is created
             # We need to set the rtc_processor to the model
@@ -344,8 +343,7 @@ class SmolVLAPolicy(PreTrainedPolicy):
         return len(self._queues[ACTION]) == 0
 
     def _rtc_enabled(self) -> bool:
-        rtc_config = getattr(self.config, "rtc_config", None)
-        return rtc_config is not None and rtc_config.enabled
+        return self.config.rtc_config is not None and self.config.rtc_config.enabled
 
     def forward(self, batch: dict[str, Tensor], noise=None, time=None) -> dict[str, Tensor]:
         """Do a full training forward pass to compute the loss"""
@@ -808,11 +806,10 @@ class VLAFlowMatching(nn.Module):
                     timestep=current_timestep,
                 )
 
-            rtc_config = getattr(self.config, "rtc_config", None)
-            if rtc_config is not None and rtc_config.enabled:
+            if self.config.rtc_config is not None and self.config.rtc_config.enabled:
                 inference_delay = kwargs.get("inference_delay")
                 prev_chunk_left_over = kwargs.get("prev_chunk_left_over")
-                execution_horizon = kwargs.get("execution_horizon", rtc_config.execution_horizon)
+                execution_horizon = kwargs.get("execution_horizon", self.config.rtc_config.execution_horizon)
 
                 v_t = self.rtc_processor.denoise_step(
                     x_t=x_t,
@@ -830,8 +827,11 @@ class VLAFlowMatching(nn.Module):
             time += dt
 
             # Record x_t after Euler step (other params are recorded in rtc_processor.denoise_step)
-            rtc_config = getattr(self.config, "rtc_config", None)
-            if rtc_config is not None and rtc_config.enabled and correction is not None:
+            if (
+                self.config.rtc_config is not None
+                and self.config.rtc_config.enabled
+                and correction is not None
+            ):
                 self.rtc_processor.track_debug(time=time, x_t=x_t)
 
             # Visualize x_t using plot_waypoints - accumulate all denoise steps
@@ -902,8 +902,7 @@ class VLAFlowMatching(nn.Module):
             xt_name = "smolvla_x_t_denoise_steps.png"
             v_name = "smolvla_v_denoise_steps.png"
 
-            rtc_config = getattr(self.config, "rtc_config", None)
-            if rtc_config is not None and rtc_config.enabled:
+            if self.config.rtc_config is not None and self.config.rtc_config.enabled:
                 xt_name = "smolvla_x_t_with_rtc_denoise_steps.png"
                 v_name = "smolvla_v_with_rtc_denoise_steps.png"
 
@@ -932,8 +931,11 @@ class VLAFlowMatching(nn.Module):
         # Plot ground truth on provided axes if available
         if use_provided_axes:
             prev_chunk_left_over = kwargs.get("prev_chunk_left_over")
-            rtc_config = getattr(self.config, "rtc_config", None)
-            if prev_chunk_left_over is not None and rtc_config is not None and rtc_config.enabled:
+            if (
+                prev_chunk_left_over is not None
+                and self.config.rtc_config is not None
+                and self.config.rtc_config.enabled
+            ):
                 plot_waypoints(
                     viz_xt_axs, prev_chunk_left_over, start_from=0, color="red", label="Ground truth"
                 )