> the cost of adding features is basically zero

Adding features was always the easy part. Maintaining the code OTOH is not going to be easier.

I see this with an experimental project I’m consciously vibecoding. The code base tends towards a spaghetti coded mess.

Of course you can put in some refactoring prompts and the AI will reorganize the code. But that makes it worse actually.

You have no mental model of the code and after a large refactoring even less.