bun

Bun example (@arcp/bun)

Run an ARCP runtime under Bun via serveArcp({...}). @arcp/bun uses Bun.serve({ websocket }) directly — no ws dependency — and is the only listener helper in the repo that runs in a non-Node environment.

The client side is unchanged: it's a normal @arcp/sdk ARCPClient talking over WebSocket. The wire protocol is runtime-agnostic, so the client can be Node or Bun and the server still works.

Run

This example splits the run command between the two sides because the server requires Bun.

In one terminal (server — Bun required):

bun run examples/bun/server.ts

In a second terminal (client — Node is fine, Bun is fine):

pnpm tsx examples/bun/client.ts
# or
bun run examples/bun/client.ts

The client submits an echo job whose result.runtime reads "bun", demonstrating that the server is in fact running under Bun. Stop the server with Ctrl+C.

What it demonstrates

• serveArcp({...}) — the Bun-native entrypoint.
• One process binds the ARCP path (/arcp); the example uses Bun's default fallback for non-ARCP requests (HTTP 404).
• DNS-rebinding protection via allowedHosts.
• Runtime portability: a Node client interoperates with a Bun runtime over the same JSON-over-WebSocket protocol.

Known limitation

@arcp/runtime's default event log uses better-sqlite3, a native Node module that does not yet load under Bun (see oven-sh/bun#4290). The @arcp/bun listener itself is Bun-native; the gap is one level up, in the runtime's storage. Once better-sqlite3 ships Bun support — or ARCPServer gains a bun:sqlite adapter — this example will run end-to-end. The wire surface, the listener, and the serveArcp API are all exercised by @arcp/bun's own unit tests in the meantime.

Configuration

Env var	Default	Used by
ARCP_DEMO_PORT	7898	both
ARCP_DEMO_URL	ws://127.0.0.1:7898/arcp	client
ARCP_DEMO_TOKEN	demo-token	both