been there. for these kinds of projects i never start with code, i start with specs. i sometimes spend days just working on the specs. once the specs are clear i start coding, which is completely different monster. basically not that different from a common workflow (spec > ticket > grooming > coding; more or less), but everything with AI.
I do the same, plus add tests from early on. New features then naturally are accompanied by more tests.
Yeah, I make sure to spend my time on the hard problems and where you need to design for the future. I use AI up to around method level after that, have it do the drudge work of typing up tedious text, or to complete required boilerplate etc.