How do you stop AI tools from turning your codebase into spaghetti?

I love using AI to speed up boilerplate and early prototypes, but after a few iterations, the code always feels untidy and hard to manage.

It feels like every time I ask AI to fix a small bug, it rewrites parts of the logic in a completely different style, making the whole file messy.

For those using AI tools in production daily: what is your personal rule or workflow to prevent AI from creating a mess in your codebase?