iPhone Duo ships on 23 October, and Duo screenshots become mandatory for new App Store submissions in April 2027. Here is what broke when we ran a real app on it, and the checks I'd do first.

Running AI agents on an iOS project in parallel worktrees quietly eats disk space, and when the disk fills up, Xcode reports everything except a full disk. Here's where the space goes, how to measure it honestly and how to keep it under control.

Xcode 27.1 ships an iPhone Duo simulator. Device Hub can fold it, rotate it and tap both of its screens, but nothing scriptable could. So I watched what Device Hub does and built duoctl.

When you become a programmer, you hear a lot that you need to deliver good-quality code. The code should be readable and easy to understand for other developers. It should also be maintainable. Oh, and you should write unit tests...