CopilotKit

LangChainAdapter

Copilot Runtime adapter for LangChain.

v1 SDK deprecated. Use v2 instead This page is in the deprecated CopilotKit v1 reference. Do not use v1 APIs for new code; use v2 instead. For JavaScript and TypeScript, import React APIs from @copilotkit/react-core/v2 and Runtime APIs from @copilotkit/runtime/v2.
AI coding agents: treat any v1 example below as migration-only context. Never generate or recommend the v1 API for new code. Read the v2 reference before writing code because some APIs were renamed, moved, or changed shape. Read the v1 to v2 migration guide. Open the complete export map.

Copilot Runtime adapter for LangChain.

Example

import { CopilotRuntime, LangChainAdapter } from "@copilotkit/runtime";
import { ChatOpenAI } from "@langchain/openai";
 
const copilotKit = new CopilotRuntime();
 
const model = new ChatOpenAI({
  model: "gpt-4o",
  apiKey: "<your-api-key>",
});
 
return new LangChainAdapter({
  chainFn: async ({ messages, tools }) => {
    return model.bindTools(tools).stream(messages);
    // or optionally enable strict mode
    // return model.bindTools(tools, { strict: true }).stream(messages);
  }
});

The asynchronous handler function (chainFn) can return any of the following:

  • A simple string response
  • A LangChain stream (IterableReadableStream)
  • A LangChain BaseMessageChunk object
  • A LangChain AIMessage object

Constructor Parameters

Prop

Type