psi

About

psi is a terminal coding agent written in ANSI C with Lua for its high-level behavior, built as a 6.4 MB portable binary. It supports Anthropic, OpenAI Codex, OpenRouter and local Ollama models, and offers a TUI, REPL, one-shot prompts and Lua evaluation. Sessions are append-only JSONL trees that can be branched and resumed with another provider. Lua extensions can add commands, tools and lifecycle hooks, and it is tested on Linux, macOS, Windows, FreeBSD, OpenBSD and Haiku.