if all your models are in the cloud, why would you trust anything your agent builds

That sounds cynical today, but that's just because the AI models are currently outrunning enshittification. I'm already pondering personal plans about what to do when that turns around. We haven't seen enshittification yet that is going to be like the enshittification of AI. It may even deserve a new term of its very own, it's going to be such a big problem. The AI companies are leaving a lot of value on the table to entice us on to their systems but at some point that's going to turn around.