Show HN: Lunar, a coding harness extensible via Lua

Lunar, a terminal coding harness extensible via Lua, has been released as an open-source tool on GitHub by developer gszr. It provides four tools—read, write, edit, and bash—and supports any OpenAI Chat Completions-compatible endpoint, including xAI's Grok-4.6 model. Lunar is early software for macOS and Linux, with Lua extensions and the Responses API planned but not yet implemented.

A terminal coding harness. You open lunar and code. Simple and fast like Pi <3 https://github.com/earendil-works/pi , but using Lua for extensions. Lunar gives the model four tools— read , write , edit , and bash —without imposing a workflow. brew install --HEAD gszr/taps/lunar Or with Cargo: cargo install --git https://github.com/gszr/lunar With no ~/.lunar/init.lua , set an API key, an OpenAI Chat Completions base URL, and a model: export LUNAR API KEY=... export LUNAR BASE URL=https://api.x.ai/v1 export LUNAR MODEL=grok-4.6 Any OpenAI Chat Completions-compatible endpoint should work. For lasting configuration, create ~/.lunar/init.lua . From Lunar, /config opens this file with $VISUAL or $EDITOR , then reloads it when the editor exits. Read the key from the environment: lunar.models { grok46 = { id = "grok-4.6", window = 500000, }, } lunar.providers { xai = { base url = "https://api.x.ai/v1", key name = "XAI API KEY", models = { "grok46" }, }, } lunar.defaults { provider = "xai", model = "grok46", } export XAI API KEY=... Or let Lunar store the credential. Use /login in the TUI xAI subscription via device code, or a masked API key . /logout removes it. lunar.models { grok46 = { id = "grok-4.6", window = 500000, }, } lunar.providers { xai = { base url = "https://api.x.ai/v1", key in = "auth", auth provider = "xai", models = { "grok46" }, }, } lunar.defaults { provider = "xai", model = "grok46", } lunar Type a prompt and press Enter. Run /help to see the available commands. Use /config to edit and reload init.lua , or lunar -c to continue the latest mission for the current directory. Lunar includes AGENTS.md , CONTEXT.md , and summaries from .agents/skills/ /SKILL.md in its context. Lua extensions are planned. For example, you will be able to replace local bash with execution in a Runta https://runta.ai runtime: -- Planned API; not implemented yet. lunar.tools.bash = function cmd local runtime = os.getenv "LUNAR RUNTIME" or "demo" return lunar.sh { "runta", "exec", runtime, "--", "sh", "-lc", cmd } end Lunar is early software for macOS and Linux. It currently supports OpenAI Chat Completions endpoints. Lua extensions and the Responses API are not implemented yet.