Purely vibe code won't work. You need to define an excellent architecture, have great specs, a solid plan, divide the plan in small phases that fit well in a context window, use TDD and automated code reviews for implementing each phase, do QA and some code review.

At any point you need to have agents review, verify and test the other agents output and iterate until the output is perfect.

And also, have good e2e tests.

IMO, if you don't spend at least a few tens of millions tokens per day, you aren't doing it properly.