Backwards compatible init

Author: steven10a

src/guardrails/_base_client.py

@@ -107,6 +107,41 @@ class GuardrailsResponse:
     _llm_response: OpenAIResponseType  # Private: OpenAI response object
     guardrail_results: GuardrailResults
 
+    def __init__(
+        self,
+        guardrail_results: GuardrailResults,
+        _llm_response: OpenAIResponseType | None = None,
+        llm_response: OpenAIResponseType | None = None,
+    ) -> None:
+        """Initialize GuardrailsResponse with backward-compatible parameter names.
+
+        Accepts both _llm_response (new) and llm_response (deprecated) parameter names
+        to maintain backward compatibility with existing code.
+
+        Args:
+            guardrail_results: The guardrail results.
+            _llm_response: The underlying OpenAI response (preferred parameter name).
+            llm_response: The underlying OpenAI response (deprecated parameter name).
+
+        Raises:
+            TypeError: If neither or both llm_response parameters are provided.
+        """
+        # Handle backward compatibility: accept both parameter names
+        if _llm_response is not None and llm_response is not None:
+            msg = "Cannot specify both 'llm_response' and '_llm_response'"
+            raise TypeError(msg)
+
+        if _llm_response is None and llm_response is None:
+            msg = "Must specify either 'llm_response' or '_llm_response'"
+            raise TypeError(msg)
+
+        # Use whichever was provided
+        response_obj = _llm_response if _llm_response is not None else llm_response
+
+        # Set fields on frozen dataclass using object.__setattr__
+        object.__setattr__(self, "_llm_response", response_obj)
+        object.__setattr__(self, "guardrail_results", guardrail_results)
+
     @property
     def llm_response(self) -> OpenAIResponseType:
         """Access the underlying OpenAI response (deprecated).

tests/unit/test_response_flattening.py

@@ -356,6 +356,38 @@ def test_separate_instances_warn_independently() -> None:
         assert len(deprecation_warnings) == 2  # noqa: S101
 
 
+def test_init_backward_compatibility_with_llm_response_param() -> None:
+    """Test that __init__ accepts both llm_response and _llm_response parameters."""
+    mock_llm_response = _create_mock_chat_completion()
+    guardrail_results = _create_mock_guardrail_results()
+
+    # Old parameter name should still work (backward compatibility)
+    response_old = GuardrailsResponse(
+        llm_response=mock_llm_response,
+        guardrail_results=guardrail_results,
+    )
+    assert response_old.id == "chatcmpl-123"  # noqa: S101
+
+    # New parameter name should work
+    response_new = GuardrailsResponse(
+        _llm_response=mock_llm_response,
+        guardrail_results=guardrail_results,
+    )
+    assert response_new.id == "chatcmpl-123"  # noqa: S101
+
+    # Both should raise TypeError
+    with pytest.raises(TypeError, match="Cannot specify both"):
+        GuardrailsResponse(
+            llm_response=mock_llm_response,
+            _llm_response=mock_llm_response,
+            guardrail_results=guardrail_results,
+        )
+
+    # Neither should raise TypeError
+    with pytest.raises(TypeError, match="Must specify either"):
+        GuardrailsResponse(guardrail_results=guardrail_results)
+
+
 def test_dir_includes_delegated_attributes() -> None:
     """Test that dir() includes attributes from the underlying llm_response."""
     mock_llm_response = _create_mock_chat_completion()