It's limited. For instance, you're going to have to explore different kinds of sandboxing if you want to prevent network access (except for certain cases, like to allow it to talk to the AI provider). But generally, a filesystem will have metadata for files like which groups are allowed to read/write, and the operating system will enforce those rules for processes that run as that user, and for any processes which that user starts. I feel like that gets you 90% of where you're likely to want to go with it.

I think it would be much better if we leaned into improving that kind of control rather than thinking about security for specifically agents. Otherwise what's to stop an agent from writing a program to do whatever it's not allowed to do, and then running that program? You want the restrictions to be enclosing around parts the process tree, not the agent itself, and OS-level restrictions have been doing that kind of things for decades.