feat(openai): Use responses API if model is gpt-5.2-pro (#34306)

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

@@ -468,6 +468,12 @@ def _handle_openai_bad_request(e: openai.BadRequestError) -> None:
     raise
 
 
+def _model_prefers_responses_api(model_name: str | None) -> bool:
+    if not model_name:
+        return False
+    return "gpt-5.2-pro" in model_name
+
+
 _BM = TypeVar("_BM", bound=BaseModel)
 _DictOrPydanticClass: TypeAlias = dict[str, Any] | type[_BM] | type
 _DictOrPydantic: TypeAlias = dict | _BM
@@ -1391,6 +1397,7 @@ class BaseChatOpenAI(BaseChatModel):
             or self.reasoning is not None
             or self.truncation is not None
             or self.use_previous_response_id
+            or _model_prefers_responses_api(self.model_name)
         ):
             return True
         return _use_responses_api(payload)

libs/partners/openai/tests/unit_tests/chat_models/test_base.py

@@ -74,6 +74,7 @@ from langchain_openai.chat_models.base import (
     _format_message_content,
     _get_last_messages,
     _make_computer_call_output_from_message,
+    _model_prefers_responses_api,
     _oai_structured_outputs_parser,
 )
 
@@ -3148,3 +3149,8 @@ def test_gpt_5_1_temperature_with_reasoning_effort_none(
     messages = [HumanMessage(content="Hello")]
     payload = llm._get_request_payload(messages)
     assert "temperature" not in payload
+
+
+def test_model_prefers_responses_api() -> None:
+    assert _model_prefers_responses_api("gpt-5.2-pro")
+    assert not _model_prefers_responses_api("gpt-5.1")