Fireworks: reasoning_content is missing

[DragosBobolea]

Checked other resources

• This is a bug, not a usage question.
• 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).
• This is not related to the langchain-community package.
• I posted a self-contained, minimal, reproducible example. A maintainer can copy it and run it AS IS.

Package (Required)

• langchain
• langchain-openai
• langchain-anthropic
• langchain-classic
• langchain-core
• langchain-cli
• langchain-model-profiles
• langchain-tests
• langchain-text-splitters
• langchain-chroma
• langchain-deepseek
• langchain-exa
• langchain-fireworks
• langchain-groq
• langchain-huggingface
• langchain-mistralai
• langchain-nomic
• langchain-ollama
• langchain-perplexity
• langchain-prompty
• langchain-qdrant
• langchain-xai
• Other / not sure / general

Example Code (Python)

from langchain_core.messages import HumanMessage
from langchain_core.tools import tool
from langchain_fireworks import ChatFireworks


@tool
def subtract(a: int, b: int) -> int:
    """Subtract two numbers together."""
    return a - b

def main():
    model = ChatFireworks(model="fireworks/glm-4p6")
    model = model.bind_tools([subtract])
    response = model.invoke([HumanMessage(content="What is 123456314532 + 12243756423?")],
    tool_choice="required")

    assert response.additional_kwargs['reasoning_content'] # fails


if __name__ == "__main__":
    main()

Error Message and Stack Trace (if applicable)

Description

reasoning_content should be propagated from the response

System Info

python 3.12
langchain==0.3.27
langchain-fireworks==0.3.0