rpi

rpi is an open-source coding agent written in Rust, published by bigfish1913 under the MIT license. It ships as a terminal agent for reading and editing code, running commands and managing sessions, and as a set of crates for embedding the same agent loop in other Rust programs. The latest GitHub release listed is v0.9.2.

What It Is

rpi is a library-first coding-agent runtime with a terminal CLI built on top of it. You can install a prebuilt single binary, configure a model provider such as Anthropic or an OpenAI-compatible gateway, and run it as an interactive TUI, a one-shot prompt, or a JSON event-stream mode. It began as a Rust reimplementation of the Pi TypeScript SDK by Mario Zechner and now has its own plugin ABI and runtime.

Architecture and SDK

The workspace is split into composable crates covering telemetry, provider and streaming types, the agent loop, built-in tools (read, write, edit, bash, grep, find, ls, powershell), session harness, terminal UI, plugin SDK, plugin host and the CLI. A deterministic faux provider lets agents and tests run offline without an API key. Sessions persist as JSONL trees and resume from the last committed frame after a crash.

Plugins and Remote Mode

Plugins are Rust cdylib libraries behind a stable C ABI and can register tools, providers, slash commands, event handlers and resources. Installable extensions include web search, web fetch and a subagents extension that exposes delegate_task with inherited configuration. Node/TypeScript extensions are described as compatibility beta features not recommended for production. A server mode runs the agent headless over TCP, with a thin TUI client connecting using a token.

Performance Claims

The project's offline benchmark on Windows 11 reports a 21.8 MiB single binary, about 10.7x faster cold start and about 7.6x lower memory at ready compared with Pi, excluding model inference.