Coding agents are good at writing Swift. They're bad at finishing it.

I've spent the last few months pointing AI coding agents at real Swift and Xcode work and watching where they come apart. Not "write me a login screen" demos. Tasks with a build, a test target, and a finish line the agent has to reach on its own. Start with the part that surprised me: the first draft is usually fine. Give a capable model a reasonable Swift task and the code it writes on the first pass is often correct, or close. The view is sensible. The types line up. If writing Swift were the