Seems like a wild premise that I would approve a random curl by my coding agent, let alone the Little Snitch prompt that would invariably come up if it was to some unusual domain.

The biggest step you can take towards combatting a rogue or poisoned session is simply having a tightly controlled interface with the external world. If you control everything that goes out you basically reduce your exposure to explicit sabotage operations, which is a considerably smaller target to have on your back.