@composio/langchain

The LangChain provider for Composio SDK, providing seamless integration with LangChain's ecosystem and tools.

Features

• LangChain Integration: Seamless integration with LangChain's ecosystem
• LCEL Support: Full support for LangChain Expression Language (LCEL)
• Streaming Support: First-class support for streaming responses
• Tool Execution: Execute LangChain tools with proper parameter handling
• Chain Integration: Work with LangChain chains and agents
• Type Safety: Full TypeScript support with proper type definitions

Installation

npm install @composio/core @composio/langchain @langchain/core @langchain/openai
# or
yarn add @composio/core @composio/langchain @langchain/core @langchain/openai
# or
pnpm add @composio/core @composio/langchain @langchain/core @langchain/openai

Environment Variables

Required environment variables:

• COMPOSIO_API_KEY: Your Composio API key
• OPENAI_API_KEY: Your OpenAI API key (or other LLM provider's key)

Optional environment variables:

• LANGCHAIN_TRACING_V2: Enable LangChain tracing (set to "true")
• LANGCHAIN_ENDPOINT: Custom LangChain API endpoint
• LANGCHAIN_API_KEY: Your LangChain API key (for hosted services)

Quick Start

import { Composio } from '@composio/core';
import { LangChainProvider } from '@composio/langchain';

// Initialize Composio with LangChain provider
const composio = new Composio({
  apiKey: 'your-composio-api-key',
  provider: new LangChainProvider(),
});

// Get available tools
const tools = await composio.tools.get('user123', {
  toolkits: ['gmail', 'googlecalendar'],
  limit: 10,
});

// Get tools with version control
const versionedTools = await composio.tools.get('user123', {
  toolkits: ['gmail'],
  toolkitVersions: { gmail: '20250909_00' },
});

// Get a specific tool
const sendEmailTool = await composio.tools.get('user123', 'GMAIL_SEND_EMAIL');

Examples

Check out our complete example implementations:

• Basic LangChain Integration
• LCEL Example
• RAG Example
• Streaming Example

Basic Chain with Streaming

import { Composio } from '@composio/core';
import { LangChainProvider } from '@composio/langchain';
import { ChatPromptTemplate } from '@langchain/core/prompts';
import { StringOutputParser } from '@langchain/core/output_parsers';
import { ChatOpenAI } from '@langchain/openai';

const composio = new Composio({
  apiKey: process.env.COMPOSIO_API_KEY,
  provider: new LangChainProvider(),
});

// Get tools for the chain
const tools = await composio.tools.get('user123', {
  toolkits: ['gmail'],
  limit: 10,
});

const model = new ChatOpenAI({
  modelName: 'gpt-4',
  streaming: true,
});

const prompt = ChatPromptTemplate.fromTemplate('Tell me a joke about {topic}');
const parser = new StringOutputParser();

const chain = prompt.pipe(model).pipe(parser);

// Stream the response
const stream = await chain.stream({
  topic: 'programming',
});

for await (const chunk of stream) {
  console.log(chunk);
}

Tool Execution with Streaming Events

import { Composio } from '@composio/core';
import { LangChainProvider } from '@composio/langchain';
import { ChatPromptTemplate } from '@langchain/core/prompts';
import { JsonOutputParser } from '@langchain/core/output_parsers';
import { ChatOpenAI } from '@langchain/openai';

const composio = new Composio({
  apiKey: process.env.COMPOSIO_API_KEY,
  provider: new LangChainProvider(),
});

// Get tools for the chain
const tools = await composio.tools.get('user123', {
  toolkits: ['gmail'],
});

const model = new ChatOpenAI({
  modelName: 'gpt-4',
  streaming: true,
});

const chain = model.pipe(new JsonOutputParser());
const eventStream = await chain.streamEvents(
  `Output a list of the countries france, spain and japan and their populations in JSON format.`,
  { version: 'v2' }
);

for await (const event of eventStream) {
  const eventType = event.event;
  if (eventType === 'on_chat_model_stream') {
    console.log(`Chat model chunk: ${event.data.chunk.content}`);
  } else if (eventType === 'on_parser_stream') {
    console.log(`Parser chunk: ${JSON.stringify(event.data.chunk)}`);
  }
}

Provider Configuration

The LangChain provider can be configured with various options:

const provider = new LangChainProvider({
  // Default model configuration
  model: new ChatOpenAI({
    modelName: 'gpt-4',
    streaming: true,
  }),
  // Custom execution modifiers
  modifiers: {
    beforeExecute: params => {
      // Transform parameters before execution
      return params;
    },
    afterExecute: response => {
      // Transform response after execution
      return response;
    },
  },
  // Enable tracing
  tracing: true,
});

API Reference

LangChainProvider Class

The LangChainProvider class extends BaseComposioProvider and provides LangChain-specific functionality.

Methods

executeToolCall(tool: Tool): Promise<string>

Executes a LangChain tool call and returns the result.

const result = await provider.executeToolCall(tool);

Contributing

We welcome contributions! Please see our Contributing Guide for more details.

License

ISC License

Support

For support, please visit our Documentation or join our Discord Community.