One of the ideas I've been experimenting with is user-guide-driven development, where I write a user guide and mockups first, and let the agents iterate from there until they match the guide. I've almost stopped using unit tests and create user-experience instead, i.e. a context-less agent goes through the guide and tries to follow it literally before the work is considered done.
I've been using it in small utils, and feel more in control of the process. tbh though, I'm not sure how far this approach can scale. I'm curious where people think this breaks.