AI fix for

uv run pytest 'tests/worker/test_workflow.py::test_workflow_activity_outbound_conversion_failure'
uv run pytest 'tests/worker/test_workflow.py::test_exception_raising_converter_param'

Author: dandavison

temporalio/converter.py

@@ -435,6 +435,21 @@ def __init__(self) -> None:
         """Create a default payload converter."""
         super().__init__(*DefaultPayloadConverter.default_encoding_payload_converters)
 
+    def with_context(self, context: SerializationContext) -> Self:
+        """Return a new instance with the given context, preserving the class type."""
+        # Create a new instance of the same class (works for subclasses too)
+        instance = self.__class__()
+        # Update the converters with context
+        instance.converters = {
+            encoding: (
+                converter.with_context(context)
+                if isinstance(converter, WithSerializationContext)
+                else converter
+            )
+            for encoding, converter in self.converters.items()
+        }
+        return instance
+
 
 class BinaryNullPayloadConverter(EncodingPayloadConverter):
     """Converter for 'binary/null' payloads supporting None values."""

temporalio/worker/_workflow_instance.py

@@ -225,12 +225,8 @@ def __init__(self, det: WorkflowInstanceDetails) -> None:
         self._workflow_input: Optional[ExecuteWorkflowInput] = None
         self._info = det.info
         self._context_free_payload_codec = det.data_converter.payload_codec
-        self._context_free_payload_converter = (
-            det.data_converter.payload_converter_class()
-        )
-        self._context_free_failure_converter = (
-            det.data_converter.failure_converter_class()
-        )
+        self._context_free_payload_converter = det.data_converter.payload_converter
+        self._context_free_failure_converter = det.data_converter.failure_converter
         self._payload_converter, self._failure_converter = (
             self._converters_with_context(
                 temporalio.converter.WorkflowSerializationContext(