openai[fix]: Correctly set usage metadata for OpenAI Responses API (#31756)

Author: MrJaeger

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

@@ -3271,19 +3271,23 @@ def _create_usage_metadata_responses(oai_token_usage: dict) -> UsageMetadata:
     input_tokens = oai_token_usage.get("input_tokens", 0)
     output_tokens = oai_token_usage.get("output_tokens", 0)
     total_tokens = oai_token_usage.get("total_tokens", input_tokens + output_tokens)
-
     output_token_details: dict = {
-        "audio": (oai_token_usage.get("completion_tokens_details") or {}).get(
-            "audio_tokens"
-        ),
-        "reasoning": (oai_token_usage.get("output_token_details") or {}).get(
+        "reasoning": (oai_token_usage.get("output_tokens_details") or {}).get(
             "reasoning_tokens"
-        ),
+        )
+    }
+    input_token_details: dict = {
+        "cache_read": (oai_token_usage.get("input_tokens_details") or {}).get(
+            "cached_tokens"
+        )
     }
     return UsageMetadata(
         input_tokens=input_tokens,
         output_tokens=output_tokens,
         total_tokens=total_tokens,
+        input_token_details=InputTokenDetails(
+            **{k: v for k, v in input_token_details.items() if v is not None}
+        ),
         output_token_details=OutputTokenDetails(
             **{k: v for k, v in output_token_details.items() if v is not None}
         ),

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

@@ -1,11 +1,17 @@
 """Standard LangChain interface tests for Responses API"""
 
+from pathlib import Path
+from typing import cast
+
 import pytest
 from langchain_core.language_models import BaseChatModel
+from langchain_core.messages import AIMessage
 
 from langchain_openai import ChatOpenAI
 from tests.integration_tests.chat_models.test_base_standard import TestOpenAIStandard
 
+REPO_ROOT_DIR = Path(__file__).parents[6]
+
 
 class TestOpenAIResponses(TestOpenAIStandard):
     @property
@@ -19,3 +25,35 @@ def chat_model_params(self) -> dict:
     @pytest.mark.xfail(reason="Unsupported.")
     def test_stop_sequence(self, model: BaseChatModel) -> None:
         super().test_stop_sequence(model)
+
+    def invoke_with_cache_read_input(self, *, stream: bool = False) -> AIMessage:
+        with open(REPO_ROOT_DIR / "README.md") as f:
+            readme = f.read()
+
+        input_ = f"""What's langchain? Here's the langchain README:
+        
+        {readme}
+        """
+        llm = ChatOpenAI(model="gpt-4.1-mini", output_version="responses/v1")
+        _invoke(llm, input_, stream)
+        # invoke twice so first invocation is cached
+        return _invoke(llm, input_, stream)
+
+    def invoke_with_reasoning_output(self, *, stream: bool = False) -> AIMessage:
+        llm = ChatOpenAI(
+            model="o4-mini",
+            reasoning={"effort": "medium", "summary": "auto"},
+            output_version="responses/v1",
+        )
+        input_ = "What was the 3rd highest building in 2000?"
+        return _invoke(llm, input_, stream)
+
+
+def _invoke(llm: ChatOpenAI, input_: str, stream: bool) -> AIMessage:
+    if stream:
+        full = None
+        for chunk in llm.stream(input_):
+            full = full + chunk if full else chunk  # type: ignore[operator]
+        return cast(AIMessage, full)
+    else:
+        return cast(AIMessage, llm.invoke(input_))

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

@@ -60,6 +60,7 @@
     _convert_message_to_dict,
     _convert_to_openai_response_format,
     _create_usage_metadata,
+    _create_usage_metadata_responses,
     _format_message_content,
     _get_last_messages,
     _oai_structured_outputs_parser,
@@ -948,6 +949,25 @@ def test__create_usage_metadata() -> None:
     )
 
 
+def test__create_usage_metadata_responses() -> None:
+    response_usage_metadata = {
+        "input_tokens": 100,
+        "input_tokens_details": {"cached_tokens": 50},
+        "output_tokens": 50,
+        "output_tokens_details": {"reasoning_tokens": 10},
+        "total_tokens": 150,
+    }
+    result = _create_usage_metadata_responses(response_usage_metadata)
+
+    assert result == UsageMetadata(
+        output_tokens=50,
+        input_tokens=100,
+        total_tokens=150,
+        input_token_details={"cache_read": 50},
+        output_token_details={"reasoning": 10},
+    )
+
+
 def test__convert_to_openai_response_format() -> None:
     # Test response formats that aren't tool-like.
     response_format: dict = {