So, rollback and try again with the insight.
AI makes it cheap to implement complex first drafts and iterations.
I'm building a CRM system for my business; first time it took about 2 weeks to get a working prototype. V4 from scratch took about 5 hours.
AI is also excellent at reverse engineering specs from existing code, so you can also ask it to reflect simple iterative changes to the code back into the spec, and use that to guide further development. That doesn't have much of an equivalent in the old Waterfall.