I don't know how "sandbox" became "prison," but exe.dev does this sort of thing pretty well, and a web UI can be as good or better than a terminal interface.
As AI complexity increases their behavior becomes more anthropomorphic, little internal loops that look a lot like human behaviors start to peak out, not just in the response, but in the internal workings of the machine. You get instinctual behaviors encoded in by training as second and third order effects.