The Fediverse is made up of it's users, mods and admins. We protect it. As a user I report suspicious content and users. The mods and admins decide and take action. As far as I know there's some automatisms as well, like automod scripts. And some code in some of the platforms themselves.

It isn't, like even a little.

I've got a wordpress instance that I've federated into the fediverse and as soon as I did I went from 2-3 spam comments a week to over 50 a week. I've since set up a honeypot and that has dropped to zero. These probably aren't AI agents but they're certainly bots (humans can't see my honeypot unless they're browsing the raw HTML and afict my audience wouldn't do that)

There is absolutely nothing stopping your from spinning up a Masotodon, Lemmy, or any other AP federated platform and unleashing AI agents all across it other than your own conscience.

Its not in any way.

There is nothing stopping someone from running up an instance and bombarding other instances with agents.

Sure you can block the instance but all it takes is a new domain registration and you are back to square 1.

Mods and reporting.

Can someone please promise to check on me so I don't die

It isn't. All that can be done is ban them when they are discovered or defederate from instances that don't do that.