The Core of a Coding Agent Is 128 Lines of Python. So I Built One From Scratch. (opens in new tab)

128 lines of Python. That's the entire core of a coding agent — the loop that powers tools like Claude Code and Cursor. I didn't believe it either, so I built one from scratch. Then I pointed it at a failing test, and it read the file, ran the test, saw the traceback, fixed the code, and re-ran it — choosing every step itself. No one hard-coded that. It's open source (MIT), with a phased roadmap you can follow: 👉 github.com/osama96gh/coding-agent-from-scratch Why build one instead of reading ...