style: apply ruff format and add test coverage for optional request params

litellm/llms/hosted_vllm/responses/transformation.py

@@ -74,7 +74,10 @@ class HostedVLLMResponsesAPIConfig(OpenAIResponsesAPIConfig):
         )
 
         for param in HOSTED_VLLM_RESPONSES_SUPPORTED_PARAMS:
-            if param in response_api_optional_request_params and response_api_optional_request_params[param] is not None:
+            if (
+                param in response_api_optional_request_params
+                and response_api_optional_request_params[param] is not None
+            ):
                 request[param] = response_api_optional_request_params[param]
             elif litellm_params is not None:
                 val = (

litellm/responses/utils.py

@@ -339,9 +339,7 @@ class ResponsesAPIRequestUtils:
         special_params: Final[dict[str, object]] = params.pop("kwargs", {})
 
         allowed_openai_params: Final = (
-            params.get("allowed_openai_params")
-            or special_params.get("allowed_openai_params")
-            or []
+            params.get("allowed_openai_params") or special_params.get("allowed_openai_params") or []
         )
         allowed_set: Final = {p for p in allowed_openai_params if isinstance(p, str)}
         default_keys: Final = set(valid_keys) | allowed_set

tests/unit/llms/hosted_vllm/responses/test_hosted_vllm_responses.py

@@ -185,7 +185,6 @@ def test_hosted_vllm_validate_environment_custom_api_key():
     assert headers.get("Authorization") == "Bearer my-custom-key"
 
 
-
 def test_hosted_vllm_responses_supported_params():
     """Test get_supported_openai_params() includes vLLM provider-specific params."""
     config = HostedVLLMResponsesAPIConfig()
@@ -254,3 +253,22 @@ def test_hosted_vllm_responses_transform_request_from_litellm_params():
     assert request["chat_template_kwargs"] == {"enable_thinking": False}
     assert request["top_k"] == 50
     assert request["min_p"] == 0.05
+
+
+def test_hosted_vllm_responses_transform_request_from_optional_request_params():
+    """Test transform_responses_api_request forwards provider params from response_api_optional_request_params."""
+    config = HostedVLLMResponsesAPIConfig()
+
+    request = config.transform_responses_api_request(
+        model="Qwen/Qwen3-8B",
+        input="test input",
+        response_api_optional_request_params={
+            "chat_template_kwargs": {"enable_thinking": False},
+            "top_k": 30,
+        },
+        litellm_params=GenericLiteLLMParams(),
+        headers={},
+    )
+
+    assert request["chat_template_kwargs"] == {"enable_thinking": False}
+    assert request["top_k"] == 30