[makeitdouble]

You're right, but it's also why vibe coding doesn't work IMHO.

We had the same situation with TDD: can we give out succinct specs and ignore what happens in the code if the specs are met ? For anything beside Hello world, the answer was no, absolutely not.

It still mattered that the logic was somewhat reasonable and you were not building a Rube Goldberg machine giving the right answers to the given tests 95% of the time. Especially as the tests didn't cover all the valid input/output nor all the possible error cases in the problem space.

It's because there's a lot happening that we need to have simple blocks that we can trust and not black boxes that were already beyond our understanding.