openai[patch]: route to Responses API if relevant attributes are set (#31645)

Following https://github.com/langchain-ai/langchain/pull/30329.

libs/partners/openai/langchain_openai/chat_models/base.py

@@ -593,8 +593,8 @@ class BaseChatOpenAI(BaseChatModel):
     """
 
     store: Optional[bool] = None
-    """If True, the Responses API may store response data for future use. Defaults to
+    """If True, OpenAI may store response data for future use. Defaults to True
-    True.
+    for the Responses API and False for the Chat Completions API.
 
     .. versionadded:: 0.3.24
     """
@@ -1074,6 +1074,12 @@ class BaseChatOpenAI(BaseChatModel):
     def _use_responses_api(self, payload: dict) -> bool:
         if isinstance(self.use_responses_api, bool):
             return self.use_responses_api
+        elif self.include is not None:
+            return True
+        elif self.reasoning is not None:
+            return True
+        elif self.truncation is not None:
+            return True
         else:
             return _use_responses_api(payload)
 
@@ -3173,7 +3179,13 @@ def _use_responses_api(payload: dict) -> bool:
     uses_builtin_tools = "tools" in payload and any(
         _is_builtin_tool(tool) for tool in payload["tools"]
     )
-    responses_only_args = {"previous_response_id", "text", "truncation", "include"}
+    responses_only_args = {
+        "include",
+        "previous_response_id",
+        "reasoning",
+        "text",
+        "truncation",
+    }
     return bool(uses_builtin_tools or responses_only_args.intersection(payload))
 
 

libs/partners/openai/tests/integration_tests/chat_models/test_responses_api.py

@@ -317,7 +317,9 @@ def test_stateful_api() -> None:
 
 
 def test_route_from_model_kwargs() -> None:
-    llm = ChatOpenAI(model=MODEL_NAME, model_kwargs={"truncation": "auto"})
+    llm = ChatOpenAI(
+        model=MODEL_NAME, model_kwargs={"text": {"format": {"type": "text"}}}
+    )
     _ = next(llm.stream("Hello"))
 
 
@@ -356,7 +358,7 @@ def test_file_search() -> None:
 def test_stream_reasoning_summary() -> None:
     llm = ChatOpenAI(
         model="o4-mini",
-        use_responses_api=True,
+        # Routes to Responses API if `reasoning` is set.
         reasoning={"effort": "medium", "summary": "auto"},
     )
     message_1 = {"role": "user", "content": "What is 3^3?"}