From 2ab8203fae70742be780092f27e40cf214c6f2f0 Mon Sep 17 00:00:00 2001
From: Xiaohan Fu <xiaohan@grayswan.ai>
Date: Tue, 27 Jan 2026 02:43:08 +0000
Subject: [PATCH] anthropic request body got mutated fix

---
 .../chat/guardrail_translation/handler.py     |  3 +-
 .../test_anthropic_guardrail_handler.py       | 49 +++++++++++++++++++
 2 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/litellm/llms/anthropic/chat/guardrail_translation/handler.py b/litellm/llms/anthropic/chat/guardrail_translation/handler.py
index f1f278e75ac..a3a3d56a136 100644
--- a/litellm/llms/anthropic/chat/guardrail_translation/handler.py
+++ b/litellm/llms/anthropic/chat/guardrail_translation/handler.py
@@ -76,7 +76,8 @@ class AnthropicMessagesHandler(BaseTranslation):
 
         chat_completion_compatible_request = (
             LiteLLMAnthropicMessagesAdapter().translate_anthropic_to_openai(
-                anthropic_message_request=cast(AnthropicMessagesRequest, data)
+                # Use a shallow copy to avoid mutating request data (pop on litellm_metadata).
+                anthropic_message_request=cast(AnthropicMessagesRequest, data.copy())
             )
         )
 
diff --git a/tests/test_litellm/llms/anthropic/chat/guardrail_translation/test_anthropic_guardrail_handler.py b/tests/test_litellm/llms/anthropic/chat/guardrail_translation/test_anthropic_guardrail_handler.py
index f8632105da5..82517b7af9e 100644
--- a/tests/test_litellm/llms/anthropic/chat/guardrail_translation/test_anthropic_guardrail_handler.py
+++ b/tests/test_litellm/llms/anthropic/chat/guardrail_translation/test_anthropic_guardrail_handler.py
@@ -37,6 +37,26 @@ class MockPassThroughGuardrail(CustomGuardrail):
         return inputs
 
 
+class MockDynamicGuardrail(CustomGuardrail):
+    """Mock guardrail that records dynamic params from request metadata."""
+
+    def __init__(self, guardrail_name: str):
+        super().__init__(guardrail_name=guardrail_name)
+        self.dynamic_params: Optional[dict] = None
+
+    async def apply_guardrail(
+        self,
+        inputs: GenericGuardrailAPIInputs,
+        request_data: dict,
+        input_type: Literal["request", "response"],
+        logging_obj: Optional[Any] = None,
+    ) -> GenericGuardrailAPIInputs:
+        self.dynamic_params = self.get_guardrail_dynamic_request_body_params(
+            request_data
+        )
+        return inputs
+
+
 class TestAnthropicMessagesHandlerStreamingOutputProcessing:
     """Test streaming output processing functionality"""
 
@@ -70,6 +90,35 @@ class TestAnthropicMessagesHandlerStreamingOutputProcessing:
             # Should return the responses unchanged
             assert result == responses_so_far
 
+
+class TestAnthropicMessagesHandlerInputProcessing:
+    """Test input processing preserves litellm_metadata for dynamic guardrails."""
+
+    @pytest.mark.asyncio
+    async def test_process_input_messages_preserves_litellm_metadata_guardrails(self):
+        handler = AnthropicMessagesHandler()
+        guardrail = MockDynamicGuardrail(guardrail_name="cygnal-monitor")
+
+        data = {
+            "model": "claude-3-5-sonnet-20241022",
+            "messages": [{"role": "user", "content": "hello"}],
+            "litellm_metadata": {
+                "guardrails": [
+                    {
+                        "cygnal-monitor": {
+                            "extra_body": {"policy_id": "policy-123"}
+                        }
+                    }
+                ]
+            },
+        }
+
+        with patch("litellm.proxy.proxy_server.premium_user", True):
+            await handler.process_input_messages(data=data, guardrail_to_apply=guardrail)
+
+        assert data.get("litellm_metadata", {}).get("guardrails")
+        assert guardrail.dynamic_params == {"policy_id": "policy-123"}
+
     @pytest.mark.asyncio
     async def test_process_output_streaming_response_empty_choices(self):
         """Test that streaming response with empty choices doesn't raise IndexError