fix(bedrock): strip client_metadata from additionalModelRequestFields

Responses API clients (e.g. Codex CLI) send a `client_metadata` field in
the request body. This leaks through kwargs into Bedrock's
`additionalModelRequestFields`, causing a 400 error:
`client_metadata: Extra inputs are not permitted`.

Strip it in `_prepare_request_params`, following the same pattern used
for `parallel_tool_calls`.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

litellm/llms/bedrock/chat/converse_transformation.py

@@ -1249,6 +1249,8 @@ class AmazonConverseConfig(BaseConfig):
             additional_request_params
         )
 
+        additional_request_params.pop("client_metadata", None)
+
         return (
             inference_params,
             additional_request_params,

tests/test_litellm/llms/bedrock/chat/test_converse_transformation.py

@@ -4146,3 +4146,23 @@ def test_transform_response_finish_reason_stop_when_json_mode_filters_all_tools(
 
     # finish_reason must be "stop", not "tool_calls"
     assert result.choices[0].finish_reason == "stop"
+
+
+def test_client_metadata_not_in_additional_model_request_fields():
+    """client_metadata from Responses API clients (e.g. Codex) must not leak into additionalModelRequestFields."""
+    config = AmazonConverseConfig()
+    model = "anthropic.claude-sonnet-4-5-20250929-v1:0"
+    messages = [{"role": "user", "content": "Hello"}]
+
+    optional_params = {"client_metadata": {"client": "codex", "version": "0.121.0"}}
+
+    request_data = config.transform_request(
+        model=model,
+        messages=messages,
+        optional_params=optional_params,
+        litellm_params={},
+        headers={},
+    )
+
+    additional = request_data.get("additionalModelRequestFields", {})
+    assert "client_metadata" not in additional