CoreCoder

Why we included this project

Claude Code runs to hundreds of thousands of lines and is closed source, so nobody can read how it actually works. CoreCoder is the stripped-down alternative: roughly a thousand lines of Python that genuinely runs, so you can set a breakpoint, change a line, and rerun to watch the agent reason and edit code step by step. The engine is a while loop that calls any large model you plug in, wrapped around a small set of file-editing tools. That makes it a solid reference for developers who want to understand how these assistants work, and a clean skeleton to fork if you want to grow your own minimal agent. It deliberately skips the features a production assistant needs, which is the point, because the gaps are where you're meant to branch off and make it yours.