`convert_to_openai_messages` does not handle the `ChatOpenAI` `response/v1` format

[jmaillefaud]

Checked other resources

• This is a bug, not a usage question. For questions, please use the LangChain Forum (https://forum.langchain.com/).
• I added a clear and descriptive title that summarizes this issue.
• I used the GitHub search to find a similar question and didn't find it.
• I am sure that this is a bug in LangChain rather than my code.
• The bug is not resolved by updating to the latest stable version of LangChain (or the specific integration package).
• I read what a minimal reproducible example is (https://stackoverflow.com/help/minimal-reproducible-example).
• I posted a self-contained, minimal, reproducible example. A maintainer can copy it and run it AS IS.

Example Code

The following AIMessages was obtained using ChatOpenAI with output_version="responses/v1", it does not get converted properly by convert_to_openai_messages:

from langchain_core.messages import AIMessage, convert_to_openai_messages
msg = AIMessage(content=[{'type': 'reasoning', 'summary': []}])
convert_to_openai_messages(msg)

Error Message and Stack Trace (if applicable)

ValueError: Unrecognized content block at messages[0].content[0] does not match OpenAI, Anthropic,
Bedrock Converse, or VertexAI format. Full content block:

{'id': 'rs_68ad72fd1a8c819ebfaec3788efd86750f6675e9a7c53b14', 'summary': [], 'type': 'reasoning'}

Description

The reasoning block type is not handled by convert_to_openai_messages.

System Info

System Information

OS: Linux
OS Version: #1 SMP PREEMPT_DYNAMIC Thu Jun 5 18:30:46 UTC 2025
Python Version: 3.13.3 (main, Apr 9 2025, 04:03:52) [Clang 20.1.0 ]

Package Information

langchain_core: 0.3.74
langchain: 0.3.27
langchain_community: 0.3.27
langsmith: 0.4.16
langchain_anthropic: 0.3.19
langchain_openai: 0.3.31
langchain_postgres: 0.0.15
langchain_sandbox: 0.0.6
langchain_text_splitters: 0.3.9
langgraph_sdk: 0.2.3
langgraph_supervisor: 0.0.29

Optional packages not installed

langserve

Other Dependencies

aiohttp<4.0.0,>=3.8.3: Installed. No version info available.
anthropic<1,>=0.64.0: Installed. No version info available.
async-timeout<5.0.0,>=4.0.0;: Installed. No version info available.
asyncpg>=0.30.0: Installed. No version info available.
dataclasses-json<0.7,>=0.5.7: Installed. No version info available.
httpx-sse<1.0.0,>=0.4.0: Installed. No version info available.
httpx<1,>=0.23.0: Installed. No version info available.
httpx>=0.25.2: Installed. No version info available.
jsonpatch<2.0,>=1.33: Installed. No version info available.
langchain-anthropic;: Installed. No version info available.
langchain-aws;: Installed. No version info available.
langchain-azure-ai;: Installed. No version info available.
langchain-cohere;: Installed. No version info available.
langchain-community;: Installed. No version info available.
langchain-core<0.4.0,>=0.2.13: Installed. No version info available.
langchain-core<0.4.0,>=0.3.56: Installed. No version info available.
langchain-core<1.0.0,>=0.3.66: Installed. No version info available.
langchain-core<1.0.0,>=0.3.72: Installed. No version info available.
langchain-core<1.0.0,>=0.3.74: Installed. No version info available.
langchain-core>=0.3.40: Installed. No version info available.
langchain-deepseek;: Installed. No version info available.
langchain-fireworks;: Installed. No version info available.
langchain-google-genai;: Installed. No version info available.
langchain-google-vertexai;: Installed. No version info available.
langchain-groq;: Installed. No version info available.
langchain-huggingface;: Installed. No version info available.
langchain-mistralai;: Installed. No version info available.
langchain-ollama;: Installed. No version info available.
langchain-openai;: Installed. No version info available.
langchain-perplexity;: Installed. No version info available.
langchain-text-splitters<1.0.0,>=0.3.9: Installed. No version info available.
langchain-together;: Installed. No version info available.
langchain-xai;: Installed. No version info available.
langchain<1.0.0,>=0.3.26: Installed. No version info available.
langgraph<0.7.0,>=0.6.0: Installed. No version info available.
langgraph>=0.4.3: Installed. No version info available.
langsmith-pyo3>=0.1.0rc2;: Installed. No version info available.
langsmith>=0.1.125: Installed. No version info available.
langsmith>=0.1.17: Installed. No version info available.
langsmith>=0.3.45: Installed. No version info available.
numpy<3,>=1.21: Installed. No version info available.
numpy>=1.26.2;: Installed. No version info available.
numpy>=2.1.0;: Installed. No version info available.
openai-agents>=0.0.3;: Installed. No version info available.
openai<2.0.0,>=1.99.9: Installed. No version info available.
opentelemetry-api>=1.30.0;: Installed. No version info available.
opentelemetry-exporter-otlp-proto-http>=1.30.0;: Installed. No version info available.
opentelemetry-sdk>=1.30.0;: Installed. No version info available.
orjson>=3.10.1: Installed. No version info available.
orjson>=3.9.14;: Installed. No version info available.
packaging>=23.2: Installed. No version info available.
pgvector<0.4,>=0.2.5: Installed. No version info available.
psycopg-pool<4,>=3.2.1: Installed. No version info available.
psycopg<4,>=3: Installed. No version info available.
pydantic-settings<3.0.0,>=2.4.0: Installed. No version info available.
pydantic<3,>=1: Installed. No version info available.
pydantic<3.0.0,>=2.7.4: Installed. No version info available.
pydantic>=2.7.4: Installed. No version info available.
pytest>=7.0.0;: Installed. No version info available.
PyYAML>=5.3: Installed. No version info available.
requests-toolbelt>=1.0.0: Installed. No version info available.
requests<3,>=2: Installed. No version info available.
requests>=2.0.0: Installed. No version info available.
rich>=13.9.4;: Installed. No version info available.
SQLAlchemy<3,>=1.4: Installed. No version info available.
sqlalchemy<3,>=2: Installed. No version info available.
tenacity!=8.4.0,<10,>=8.1.0: Installed. No version info available.
tenacity!=8.4.0,<10.0.0,>=8.1.0: Installed. No version info available.
tiktoken<1,>=0.7: Installed. No version info available.
typing-extensions>=4.7: Installed. No version info available.
vcrpy>=7.0.0;: Installed. No version info available.
zstandard>=0.23.0: Installed. No version info available.