Do you have examples of where this actually worked for you? How large was the codebase, how long did you have agents generate the mess in it?
I ask because my experience is pretty different, even with Opus 5.5 and Astra - unleashing agents on a messy, vibe coded repo only seems to increase the mess. The agents just slow down more and more as they keep generating further mess, they make more and more incorrect assumptions based on bad code previous agents left behind, and I grow more disappointed in their capabilities every day.
Actually reviewing all agent output thoroughly is the only effective way I've personally found of working with agents. In order to ensure that every line of code they add is actually there for a good reason, and not organized in a way that future agents will miss it, or misinterpret it. It's the only way I can prevent them from producing worse results as the repo grows.