> Agents need packages like the rest of us. Ruby gems, npm packages, Maven, pip, docker images..

Yes, yes they do, but read through artifact proxies are dodgy as fuck, which is why and facebook (and I assume a fuckload others) don't have them.

Also semi-airgapped labs are a lot less expensive than you think at that scale. Once you have to do multi-region VLANs with machine certs before you get access to juicy VLANs, the difference between "no internet for you" and "mostly airgapped" falls to almost zero.

Also I would want an artifact mirror because a) that give a good signal about how the model reacts, and what training material its latched onto, b) it hides what the models are doing from the outside.

You don't need a full air gap. Set up a microVM with network access limited to local network and send all package requests through a filtering gateway that only allows normal download endpoints. Or self host a big collection of popular packages if you need extra security.