Thanks! It's just infra, so you could do what you wanted. The clients include a safety reminder, and the datastructures include "unsafe" in the name of the inputs passed around, but that's just a little hygiene.

There really aren't good messaging libraries that provide what I wanted, so I built it. Basically I started with "signal but no need to have a phone number." I've used it to build a group messaging iOS app for friends, and just pass it to an agent all the time if I want them to be able to direct message.

The group API approval is modeled off of multi signature approval mechanics from Ethereum - so, you could use it like you describe: "Only allow this call if it passes safety checks from n reviewers", or you could have human in the loop, or a program that checks business rules + an agent and a human, etc. etc. I just wanted something that let us control API calls properly.