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Lampson — an open-source AI coding agent that lives in your project

Terminal or browser, any OpenAI- or Anthropic-compatible model, and tools that cannot leave your repo by construction. Lampson is a coding agent written entirely in Synsema.

Lampson is a coding agent you point at a folder. It reads, edits and runs code, asks before anything risky, and works from the terminal or a browser tab. It is free, open source, and written in Synsema from the first line — which is why it can promise things most agents cannot.

Two commands§

npm i -g lampson          # or the one-line installer for Windows, macOS, Linux
cd your-project
lampson                   # terminal · lampson --web → http://127.0.0.1:8080

Pick a provider on first run: DeepSeek, Anthropic, OpenAI, Groq, Ollama, MiniMax, OpenRouter — one line in .env to switch.

Confined by the language, not by a prompt§

Every Lampson tool declares its capabilities, and the Synsema runtime enforces them: file tools can only touch the mounted project (absolute paths, .. and sibling folders are refused before the tool runs), the shell runs from the project root, and a destructive system command is refused in every mode. Permission modes are yours: ask (approve dangerous commands), yolo, strict.

What comes in the box§

  • Sub-agents that run in parallel on real threads, with their own context and a restricted

toolset, or in the background with the report landing in the parent's inbox.

  • Scheduled tasks — "every morning run the tests and tell me" — with approvals you answer from

your phone through one-time links.

  • Plugins in any language, off by default until you switch them on; MCP servers with the

JSON you already have; language servers for real go-to-definition; project memory it rereads next session; a real terminal in the browser.

Why Synsema§

A harness is a server, a tool runner, a permission system, a process supervisor and a UI. In Synsema those are language features — serve, proc_spawn, capabilities, agents on threads, approve — so the whole of Lampson fits in a codebase one person can read. Lampson is the proof that the language is enough for a real agent.

Try it: lampson.org has the quickstart and the docs. If you would rather see the language first, try.synsema.org runs it in your browser.

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