This is a tangential point (this post is not really about TUIs; sort of the opposite) and I think lots of people know it already but I only figured it out last week and so can't resist sharing it: agents are good at driving tmux, and with tmux as a "browser", can verify TUI layouts.
So you can draw layouts like this and prompt Claude or Gemini with them, and get back working versions, which to me is space alien technology.
So you can draw layouts like this and prompt Claude or Gemini with them, and get back working versions, which to me is space alien technology.