yangshun/teenycode

Teenycode is a minimal coding assistant that runs in the terminal and is built for learning purposes. It connects to OpenAI's API and can read, list, and edit files in whatever folder you run it from, responding to plain-language instructions you type into a chat prompt. The entire project is around 200 lines of TypeScript code, intentionally kept small so that anyone curious about how AI coding tools work can read through the source and understand each part. The README explicitly states this is an educational project, not a production tool, and it credits a guide by Amp as the starting point. The agent has three built-in file tools: one to read a file's contents, one to list files and folders in a directory, and one to make a specific text replacement inside a file or create a new file. There is no ability to run shell commands, which the README notes is an intentional omission for safety reasons, though you can add that yourself. Getting started is straightforward. You need an OpenAI API key, which you either set as an environment variable or put in a local configuration file. From there you can run the tool directly without cloning the repository using a single command, or clone it and run from source if you want to modify the code. The tool is meant to demonstrate the core loop of an AI agent: receive a message, decide which file tool to use, call that tool, observe the result, and respond. For anyone who wants to understand how tools like GitHub Copilot or Claude Code work at their simplest, this project offers a readable starting point.