What I'm interested in with WoT relays is how you can gossip notes between them In a WoT model, you end up with a set of npubs you definitely want to fetch notes for. So the relay itself can subscribe to their notes from their outboxes. But if more people use WoT relays like this, then you could end up with many redundant subscriptions. So instead of a subscription, I was thinking of a gossip scheme where you ask a relay to notify you of just nevents for a given filter, and you can request the ones you're missing and vice versa. It's not exactly negentropy, but I guess it's kind of similar.