@langgraph-toolkit/adapter-express

Keep the graph portable and let Express absorb the HTTP wiring. The adapter exposes a compiled graph, builder, registry, or runtime through JSON and Server-Sent Events without moving checkpoint, actor, policy, provider, or MCP configuration into request handlers.

Install

npm install express @langgraph-toolkit/core @langgraph-toolkit/adapter-express

Zero-config factory

import express from "express";
import { createExpressAdapter } from "@langgraph-toolkit/adapter-express";
import { resource } from "./resource.js";

const adapter = createExpressAdapter(resource.runtime);
const app = express();

app.use(express.json());
app.use(adapter.middleware);
app.use("/agents", adapter.router);
app.listen(Number(process.env.PORT ?? 3000));

The factory normalizes one graph or an existing registry and returns { graph, runtime, router, middleware }. It defaults to /agents/:name/run and /agents/:name/stream; pass path or apiKey only when needed.

Host-native escape hatch

When a host needs complete route-level control, use langgraphRouter({ runtime, path, apiKey }) and sseMiddleware directly. The adapter serves graph listing, JSON execution, and typed SSE events while the resource remains framework-neutral.

| Concern | Express adapter | Core or resource | |---|---|---| | JSON parsing and response lifecycle | Yes | No | | SSE headers and event encoding | Yes | No | | Graph topology and typed state | No | Yes | | MCP credentials and tool policy | No | MCP/resource | | Checkpoint and actor defaults | No | Graph runtime |

Development

npm install
npm run build
npm test

License

MIT