[Fix] Fix the path resolve issue in windows

src/lerobot/configs/eval.py

@@ -45,7 +45,8 @@ def __post_init__(self) -> None:
         if policy_path:
             cli_overrides = parser.get_cli_overrides("policy")
             self.policy = PreTrainedConfig.from_pretrained(policy_path, cli_overrides=cli_overrides)
-            self.policy.pretrained_path = Path(policy_path)
+            # Keep as string to preserve forward slashes for HuggingFace repo IDs
+            self.policy.pretrained_path = policy_path
 
         else:
             logger.warning(

src/lerobot/configs/policies.py

@@ -74,7 +74,7 @@ class PreTrainedConfig(draccus.ChoiceRegistry, HubMixin, abc.ABC):  # type: igno
     license: str | None = None
     # Either the repo ID of a model hosted on the Hub or a path to a directory containing weights
     # saved using `Policy.save_pretrained`. If not provided, the policy is initialized from scratch.
-    pretrained_path: Path | None = None
+    pretrained_path: str | None = None
 
     def __post_init__(self) -> None:
         if not self.device or not is_torch_device_available(self.device):

src/lerobot/configs/train.py

@@ -75,7 +75,8 @@ def validate(self) -> None:
             # Only load the policy config
             cli_overrides = parser.get_cli_overrides("policy")
             self.policy = PreTrainedConfig.from_pretrained(policy_path, cli_overrides=cli_overrides)
-            self.policy.pretrained_path = Path(policy_path)
+            # Keep as string to preserve forward slashes for HuggingFace repo IDs
+            self.policy.pretrained_path = policy_path
         elif self.resume:
             # The entire train config is already loaded, we just need to get the checkpoint dir
             config_path = parser.parse_arg("config_path")
@@ -92,7 +93,8 @@ def validate(self) -> None:
 
             policy_dir = Path(config_path).parent
             if self.policy is not None:
-                self.policy.pretrained_path = policy_dir
+                # Convert to string with forward slashes for consistency
+                self.policy.pretrained_path = policy_dir.as_posix()
             self.checkpoint_path = policy_dir.parent
 
         if self.policy is None:
@@ -136,11 +138,41 @@ def __get_path_fields__(cls) -> list[str]:
         return ["policy"]
 
     def to_dict(self) -> dict[str, Any]:
-        return draccus.encode(self)  # type: ignore[no-any-return]  # because of the third-party library draccus uses Any as the return type
+        # Convert Path objects to POSIX-style strings to avoid Windows backslashes
+        if isinstance(self.output_dir, Path):
+            output_dir_backup = self.output_dir
+            self.output_dir = self.output_dir.as_posix()  # type: ignore[assignment]
+        if isinstance(self.checkpoint_path, Path):
+            checkpoint_path_backup = self.checkpoint_path
+            self.checkpoint_path = self.checkpoint_path.as_posix()  # type: ignore[assignment]
+
+        try:
+            return draccus.encode(self)  # type: ignore[no-any-return]  # because of the third-party library draccus uses Any as the return type
+        finally:
+            # Restore Path objects
+            if isinstance(self.output_dir, str) and "output_dir_backup" in locals():
+                self.output_dir = output_dir_backup
+            if isinstance(self.checkpoint_path, str) and "checkpoint_path_backup" in locals():
+                self.checkpoint_path = checkpoint_path_backup
 
     def _save_pretrained(self, save_directory: Path) -> None:
-        with open(save_directory / TRAIN_CONFIG_NAME, "w") as f, draccus.config_type("json"):
-            draccus.dump(self, f, indent=4)
+        # Convert Path objects to POSIX-style strings to avoid Windows backslashes in saved configs
+        if isinstance(self.output_dir, Path):
+            output_dir_backup = self.output_dir
+            self.output_dir = self.output_dir.as_posix()  # type: ignore[assignment]
+        if isinstance(self.checkpoint_path, Path):
+            checkpoint_path_backup = self.checkpoint_path
+            self.checkpoint_path = self.checkpoint_path.as_posix()  # type: ignore[assignment]
+
+        try:
+            with open(save_directory / TRAIN_CONFIG_NAME, "w") as f, draccus.config_type("json"):
+                draccus.dump(self, f, indent=4)
+        finally:
+            # Restore Path objects
+            if isinstance(self.output_dir, str) and "output_dir_backup" in locals():
+                self.output_dir = output_dir_backup
+            if isinstance(self.checkpoint_path, str) and "checkpoint_path_backup" in locals():
+                self.checkpoint_path = checkpoint_path_backup
 
     @classmethod
     def from_pretrained(