> Linux-only
What other dev OSs are there?
> once privileges are dropped [...] it doesn't appear to be possible to reinstate them
I don't understand. If unprivileged code could easily re-elevate itself, privilege dropping would be meaningless ... If you need to communicate with the outside, you can do so via sockets (such as the bind-mounted X11 socket in one of the readme Examples).
I happen to use a Mac, even when targeting Linux so I'd have to use a container or VM anyways. It's nice how lightweight bubblewrap would be however.
Consider one wanted to replicate the human-approval workflow that most agent harnesses offer. It's not obvious to me how that could be accomplished by dropping privileges without an escape hatch.