"Two weeks of warranty" jumped out at me. That's like "you have two weeks to find the thing we broke, or else we aren't responsible for it." In my experience, a good bug can hide for months more than two weeks! My codebases are definitely not in the target demographic for this service, though, and maybe if I were in the target group (bunch of LLM slop, trying to dig out of the hole, presumably no shipping product or existing userbase yet) the proposition would appeal to me.

This is a fair point. But these days bugs are not so scary anymore, so a client can vibecode a fix faster then getting me to fix it. Of course if Opus can't figure it out, I would always try to help. I have never left a client alone, warranty or not. This is just how I was raised.

If the client has an extensive suite of automated tests assessing if the software is meeting its requirements, it should be possible for them to flush out most regressions within minutes or hours, not weeks.

If the client hasn't invested in setting that up, the resulting situation is the clients' responsibility.