OpenTubeX is an open-source, privacy-focused YouTube client for Windows, macOS, Linux and Android, with experimental iOS builds. It started on December 30, 2025 as a fork of FreeTube, and I have developed it independently since then. You can watch without ads or a Google account, and your subscriptions, playlists and history stay on your device unless you turn on sync.

Most of the code since the fork was written by AI coding agents. I mostly used Claude and OpenAI's Codex through T3 Code. I chose what to build, reviewed the results and wrote the rules. This post covers the setup that keeps that working.

The numbers

Since the fork, as of October 29, 2026:

about 3,790 commits on top of upstream

1,826 merged pull requests

68 releases

about 3,100 end-to-end tests in 400 spec files, running against the packaged Electron app

The rules live in AGENTS.md

The repository has an AGENTS.md file that every agent reads before it starts. It is 87 lines long and has changed 63 times.…