[responsesAPI] parse reasoning item input (#28248)

Signed-off-by: Andrew Xia <axia@fb.com>
Co-authored-by: Andrew Xia <axia@fb.com>
Co-authored-by: Cyrus Leung <tlleungac@connect.ust.hk>

tests/entrypoints/openai/test_response_api_with_harmony.py

@@ -35,7 +35,7 @@ GET_WEATHER_SCHEMA = {
 
 @pytest.fixture(scope="module")
 def server():
-    args = ["--enforce-eager", "--tool-server", "demo"]
+    args = ["--enforce-eager", "--tool-server", "demo", "--max_model_len", "5000"]
     env_dict = dict(
         VLLM_ENABLE_RESPONSES_API_STORE="1",
         PYTHON_EXECUTION_BACKEND="dangerously_use_uv",
@@ -550,6 +550,31 @@ def call_function(name, args):
         raise ValueError(f"Unknown function: {name}")
 
 
+@pytest.mark.asyncio
+@pytest.mark.parametrize("model_name", [MODEL_NAME])
+async def test_reasoning_item(client: OpenAI, model_name: str):
+    response = await client.responses.create(
+        model=model_name,
+        input=[
+            {"type": "message", "content": "Hello.", "role": "user"},
+            {
+                "type": "reasoning",
+                "id": "lol",
+                "content": [
+                    {
+                        "type": "reasoning_text",
+                        "text": "We need to respond: greeting.",
+                    }
+                ],
+                "summary": [],
+            },
+        ],
+        temperature=0.0,
+    )
+    assert response is not None
+    assert response.status == "completed"
+
+
 @pytest.mark.asyncio
 @pytest.mark.parametrize("model_name", [MODEL_NAME])
 async def test_function_calling(client: OpenAI, model_name: str):