Module protocol 

The line protocol: one JSON object per line, in and out.

This is what makes a bot in any language possible without this crate knowing anything about that language. Every language can spawn a process and write lines to a pipe; none of them need FFI, native modules, or a package we have to release in lockstep.

The framing is the one LSP, esbuild, and MCP all converged on:

• one JSON object per line, no embedded newlines
• stdout carries only protocol messages; stderr is for logs — a client must never read stderr output as failure
• closing stdin is the graceful shutdown; there is no daemon, no PID file, and no lifetime for anyone to manage
• a version handshake on the first exchange, so changing the protocol later does not break every existing bot (ripgrep’s --json shipped without one, and that is the cautionary tale)

Requests carry an id that responses echo. Only one request is in flight at a time today — that keeps the implementation free of an async runtime — but the id means concurrency can arrive later without a breaking change.

Structs

Request

A request from the client.

Response

A response to the client. Always exactly one per request.

Enums

RequestBody

What the client wants done.

ResponseBody

Constants

PROTOCOL_VERSION

The protocol version this build speaks. Bumped only for changes a client could notice.

Functions

id_in

Best-effort read of a line’s id, for correlating an error with the request that caused it.

parse_request

Parse one line into a request.

supported_verbs

Every step name this build understands — the handshake’s answer to “what can you do”.