I'd highly recommend working top down, getting it to outline a sane architecture before it starts coding. Then if one of the modules starts getting fouled up, start with a clean sheet context (for that module) incorporating any cautions or lessons learned from the bad experience. LLMs are not yet good at working and reworking the same code, for the reasons you outline. But they are pretty good at a "Groundhog Day" approach of going through the implementation process over and over until they get it right.

+1 if you are vibe coding projects from scratch. if the architecture you specify doesn't make sense, the llm will start struggling, the only way out of their misery is mocking tests. the good thing is that a complete rewrite with proper architecture and lessons learned is now totally affordable.