If the LLM just wrote the whole thing last week, surely it can write it again.

If an LLM wrote the whole project last week and it already requires a full rewrite, what makes you think that the quality of that rewrite will be significantly higher, and that it will address all of the issues? Sure, it's all probabilistic so there's probably a nonzero chance for it to stumble into something where all the moving parts are moving correctly, but to me it feels like with our current tech, these odds continue shrinking as you toss on more requirements and features, like any mature project. It's like really early LLMs where if they just couldn't parse what you wanted, past a certain point you could've regenerated the output a million times and nothing would change.

* With a slightly different set of assumption, which may or may not matter. UAT is cheap.

And data migration is lossy, becsuse nobody care the data fidelity anyway.

Broken though