My very first sentence:

> And everyone else's work has to be completely put on hold

On a big enough team, getting everyone to a stopping point where they can wait for you to do your big bang refactor to the entire code base- even if it is only a day later- is still really disruptive.

The last time I went through something like this, we did it really carefully, migrating a page at a time from a multi page application to a SPA. Even that required ensuring that whichever page transitioned didn't have other people working on it, let alone the whole code base.

Again, I simply don't buy that you're going to be able to AI your way through such a radical transition on anything other than a trivial application with a small or tiny team.