stdio

Stdio (parent spawns child)

Demonstrates the §4.2 / §22 stdio transport. Unlike the other examples, there is no TCP/WebSocket server: the parent process spawns the runtime as a child subprocess, and the two communicate over the child's stdin/stdout using newline-delimited JSON envelopes (one envelope per line).

This is the same wire format the spec mandates for stdio deployments (useful for tools like editor plugins or sandboxed runtimes where you want the lifetime of the runtime tied to the client process).

Run

A single command — the client spawns its own runtime:

pnpm tsx examples/stdio/client.ts

How it works

• client.ts (parent) spawns server.ts as a child via pnpm tsx <server.ts> with stdio: ["pipe", "pipe", "inherit"]. The child's stdout becomes the runtime's outbound frames; the child's stderr is piped to the parent's terminal for diagnostic visibility.
• server.ts (child) constructs StdioTransport.fromProcess() — binding the transport to its own process.stdin / process.stdout — and server.accepts it.
• The client builds StdioTransport.fromChild(child) and runs the normal handshake / submit / await flow on top.

Logs from the server go to stderr because stdout is the wire.

What it demonstrates

• §4.2 / §22 stdio as an MTI transport equivalent to WebSocket.
• Each ARCP envelope is a single line of JSON terminated by \n.
• The same ARCPServer and ARCPClient code works unchanged across transports — only the Transport instance differs.

Configuration

Env var	Default	Used by
ARCP_DEMO_TOKEN	demo-token	both