Kernel Protocol

rat communicates with kernel subprocesses over JSON lines on stdin/stdout. The full specification is in KERNEL-PROTOCOL.md.

MCP tools

Every kernel exposes exactly four MCP tools:

Tool	What it does
`run`	Execute code or provide input
`look`	Inspect variables, complete code, see state
`tail`	Recent activity log
`ctl`	Reset, cancel, restart

Wire format

The kernel reads JSON requests from stdin (one per line) and writes JSON responses to stdout (one per line). Stderr is reserved for the language runtime’s own diagnostics.

{"id":"1","method":"run","params":{"code":"x = 42"}}

{"id":"1","result":{"output":"","error":null}}

See the full KERNEL-PROTOCOL.md for request/response schemas, streaming, and error handling.