<del>The federated approach would be the same way that we distinguish cooluser@gmail.com from cooluser@proton.me; in this case, the server part would just deter

<del>The federated approach would be the same way that we distinguish cooluser@gmail.com from cooluser@proton.me; in this case, the server part would just determine who you're asking to map cooluser to a UUID.</del> Actually, this is handled pretty clearly in the example article.