feat(processor): implement migration detection and error handling for processor configurations (#1968)

* feat(processor): implement migration detection and error handling for processor configurations

- Added ProcessorMigrationError to handle migration requirements for old model formats.
- Enhanced DataProcessorPipeline.from_pretrained to include robust migration detection logic.
- Implemented methods for resolving configuration sources, validating loaded configs, and checking for valid processor configurations.
- Introduced comprehensive tests for migration detection and configuration validation to ensure correct behavior.

* refactor(processor): simplify loading logic and enhance migration detection

- Refactored DataProcessorPipeline to implement a simplified three-way loading strategy for configuration files.
- Introduced explicit config_filename parameter to avoid ambiguity during loading.
- Updated ProcessorMigrationError to provide clearer error messages for migration requirements.
- Enhanced tests to cover new loading logic and ensure proper migration detection.
- Removed deprecated methods related to config source resolution.

Author: AdilZouitine

src/lerobot/processor/pipeline.py

@@ -239,7 +239,9 @@ def test_act_processor_save_and_load():
         preprocessor.save_pretrained(tmpdir)
 
         # Load preprocessor
-        loaded_preprocessor = DataProcessorPipeline.from_pretrained(tmpdir)
+        loaded_preprocessor = DataProcessorPipeline.from_pretrained(
+            tmpdir, config_filename="policy_preprocessor.json"
+        )
 
         # Test that loaded processor works
         observation = {OBS_STATE: torch.randn(7)}

tests/processor/test_act_processor.py

@@ -290,7 +290,10 @@ def test_save_and_load_pretrained():
 
         # Load pipeline
         loaded_pipeline = DataProcessorPipeline.from_pretrained(
-            tmp_dir, to_transition=identity_transition, to_output=identity_transition
+            tmp_dir,
+            config_filename="batchpipeline.json",
+            to_transition=identity_transition,
+            to_output=identity_transition,
         )
 
         assert loaded_pipeline.name == "BatchPipeline"
@@ -325,7 +328,10 @@ def test_registry_based_save_load():
     with tempfile.TemporaryDirectory() as tmp_dir:
         pipeline.save_pretrained(tmp_dir)
         loaded_pipeline = DataProcessorPipeline.from_pretrained(
-            tmp_dir, to_transition=identity_transition, to_output=identity_transition
+            tmp_dir,
+            config_filename="dataprocessorpipeline.json",
+            to_transition=identity_transition,
+            to_output=identity_transition,
         )
 
         # Verify the loaded processor works

tests/processor/test_batch_processor.py

@@ -250,7 +250,9 @@ def test_classifier_processor_save_and_load():
         preprocessor.save_pretrained(tmpdir)
 
         # Load preprocessor
-        loaded_preprocessor = DataProcessorPipeline.from_pretrained(tmpdir)
+        loaded_preprocessor = DataProcessorPipeline.from_pretrained(
+            tmpdir, config_filename="classifier_preprocessor.json"
+        )
 
         # Test that loaded processor works
         observation = {

tests/processor/test_classifier_processor.py

@@ -324,7 +324,9 @@ def test_save_and_load_pretrained():
         robot_processor.save_pretrained(tmpdir)
 
         # Load
-        loaded_processor = DataProcessorPipeline.from_pretrained(tmpdir)
+        loaded_processor = DataProcessorPipeline.from_pretrained(
+            tmpdir, config_filename="device_test_processor.json"
+        )
 
         assert len(loaded_processor.steps) == 1
         loaded_device_processor = loaded_processor.steps[0]

tests/processor/test_device_processor.py

@@ -258,7 +258,9 @@ def test_diffusion_processor_save_and_load():
         preprocessor.save_pretrained(tmpdir)
 
         # Load preprocessor
-        loaded_preprocessor = DataProcessorPipeline.from_pretrained(tmpdir)
+        loaded_preprocessor = DataProcessorPipeline.from_pretrained(
+            tmpdir, config_filename="policy_preprocessor.json"
+        )
 
         # Test that loaded processor works
         observation = {