Vibing a Non-Trivial Ghostty Feature (mitchellh.com)

A Ghostty developer shipped an unobtrusive macOS automatic-updates UI that was largely developed with agentic AI tooling. Instead of modal update prompts, the feature surfaces a small SwiftUI “pill” in the window titlebar (via titlebar accessory controllers) and, where titlebar layouts conflict or the titlebar is hidden, a bottom-right overlay over the terminal content. The integration hooks into Sparkle by customizing SPUUserDriver and required both frontend SwiftUI prototyping and backend update-driver work. The author recorded every agentic coding session (and tracked token cost), iterating between AI-produced drafts and manual edits until shipping. Technically notable: the workflow leaned on AI for rapid UI prototyping and filling scaffolds, but hit limits on complex layout bugs and backend architecture. A critical layout conflict with tab-bar accessory views forced a design pivot to an overlay fallback. The developer manually refactored the view model from an optional-heavy struct to a tagged-union shape, improving state representation before resuming agent-assisted cleanup, documentation, and polish. The story illustrates practical agentic programming patterns: use AI as a muse and rapid prototyper, scaffold tasks for reliable “fill-in-the-blank” work, document to help future agents, and keep humans in the loop for debugging and architectural decisions.