Next.js

Mount the handler

The route file must be a catch-all ([...chatpack]) - Chatpack serves many sub-paths under basePath (default /api/chat), so a single app/api/chat/route.ts would 404 everything but the root.

import { chat } from "@/lib/chat";

export const { GET, POST, PATCH, DELETE } = chat.handler();

The instance itself lives in one shared module:

import { chatpack, type ChatpackInstance } from "@chatpack/core";
import { memoryAdapter } from "@chatpack/adapter-memory";

// globalThis guard: next dev HMR re-evaluates modules - don't reset state
const g = globalThis as typeof globalThis & { __chatpack__?: ChatpackInstance };
export const chat = (g.__chatpack__ ??= chatpack({
  storage: memoryAdapter(),
  auth: async (req) => {
    const session = await getSessionFromCookie(req.headers.get("cookie"));
    return session ? { id: session.userId } : null;
  },
}));

Custom base path

Mounting somewhere other than /api/chat? Tell the handler:

export const { GET, POST, PATCH, DELETE } = chat.handler({
  basePath: "/api/messaging",
});

Deployment notes

• next start on a long-lived server (Railway, Fly, Render, a VPS): SSE and even the memory adapter work as-is.
• Vercel / serverless: each invocation may hit a different isolate - use the Drizzle adapter and poll for new messages instead of relying on /stream. Details in Deployment.

Runnable example

examples/next-backend is the quickstart as a runnable Next.js app, with a curl walkthrough.