Add equivalent of Python's `extra_body` in LangGraph JS SDK

OSS Product Help LangChain
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1

Problem Description
In the Python LangChain/LangGraph SDK, the ChatOpenAI class supports an extra_body parameter that allows passing additional parameters to the OpenAI API client:

Python example:

# Python Example
chat = ChatOpenAI(
    extra_body={
        "custom_parameter": "value"
    }
)

The current JavaScript/TypeScript implementation lacks a direct equivalent for adding custom body parameters to API requests.

Use Cases
Developers might want to:

  • Include additional metadata with API calls
  • Support experimental or vendor-specific API parameters
  • Maintain feature parity with the Python SDK

Proposed Solution
Add a configuration option in the LangGraph JS SDK’s ChatOpenAI class that allows passing extra body parameters, similar to the Python implementation.

const chat = new ChatOpenAI({
    extraBody: {
        custom_parameter: "value"
    }
});