Connect a LangChain agent to Novu Connect. Return a LangChainAgentConfig from onMessage; Novu invokes the agent and delivers the reply on Slack. The same handler works on other providers after you link them.

This guide uses Slack first and assumes an existing Node.js app.

Prerequisites

• A Novu account
• Node.js 22+
• An existing app with LangChain agent logic
• A Slack workspace where you can install apps
• An OPENAI_API_KEY or ANTHROPIC_API_KEY (or another LangChain provider key)

Connect an existing app

In the Novu dashboard:

1. Go to Agents → Create agent.
2. Under Custom code, pick LangChain.
3. Set Agent name and Identifier (your code must use the same identifier).
4. Select Slack, generate a Slack App Configuration Token, paste it, and finish the install / Allow flow.

Alternatively run npx novu connect, choose LangChain and Slack, and skip creating a starter project when prompted. Screenshots: Create a Slack app. </Step>

Add to .env.local:

NOVU_SECRET_KEY=your-novu-secret-key
OPENAI_API_KEY=sk-...   # or ANTHROPIC_API_KEY

Create app/novu/agents/<your-identifier>.ts. Match agent('...') to the dashboard Identifier.

export const supportBot = agent('support-bot', { onMessage: async (_message, ctx) => ({ model: 'openai:gpt-4o', system: 'You are a helpful support agent. Keep answers short.', }), });

  </Tab>
  <Tab title="Claude">
```typescript
import { agent } from '@novu/framework/langchain';

export const supportBot = agent('support-bot', {
  onMessage: async (_message, ctx) => ({
    model: 'anthropic:claude-sonnet-4-20250514',
    system: 'You are a helpful support agent. Keep answers short.',
  }),
});

Export from app/novu/agents/index.ts:

export { supportBot } from './support-bot';

Returning { model, system } is a LangChainAgentConfig. Novu calls createAgent().invoke() and posts the final text. Novu maps ctx.history on this path.

On Next.js, add LangChain packages to serverExternalPackages for Turbopack. See Next.js and Turbopack. </Step>

import { serve } from '@novu/framework/next';
import { supportBot } from '../../novu/agents';

export const { GET, POST, OPTIONS } = serve({
  agents: [supportBot],
});

For Express, Hono, and other servers, see Connecting your app. </Step>

npx novu dev --port 4000

DM or @mention the bot in Slack. The reply should come from your LangChain handler in the same thread. </Step>

Tool approval

Gate a tool with needsApproval:

import { tool } from '@langchain/core/tools';
import { agent } from '@novu/framework/langchain';
import { z } from 'zod';

const issueRefund = tool(
  async ({ orderId }) => ({ orderId, status: 'refunded' }),
  {
    name: 'issueRefund',
    description: 'Issue a refund for an order',
    schema: z.object({ orderId: z.string() }),
  },
);

export const supportBot = agent('support-bot', {
  onMessage: async (_message, ctx) => ({
    model: 'openai:gpt-4o',
    system: 'You are a helpful support agent. Use issueRefund only when the user asks for a refund.',
    tools: [issueRefund],
    needsApproval: (toolCall) => toolCall.name === 'issueRefund',
  }),
});

See Tool approval and the LangChain reference.

Scaffold with the CLI

npx novu connect

Choose LangChain, authenticate the model, connect Slack, and accept the starter project. Then run npm run dev:novu.

For an existing codebase, use Connect an existing app instead.

FAQ

Set this up with an AI assistant

<Prompt description="Connect my LangChain agent to Slack with Novu" icon="plug" actions={["copy", "cursor"]}>

Connect a LangChain agent to Slack with Novu Connect

Follow https://docs.novu.co/agents/get-started/langchain

Goal

Add Novu bridge + LangChain config handler to this repo and connect Slack. Prefer the existing project over scaffolding a new one.

Rules

ALWAYS:

• Match agent('id') to the Novu dashboard agent Identifier
• Return a LangChainAgentConfig so Novu can invoke the agent
• Keep handlers channel-agnostic
• Follow the project's package manager and TypeScript conventions

NEVER:

• Hardcode API keys
• Rebuild conversation history manually when returning a config

Next steps