What NIP is that?
Discussion
the OK from relay to client is described in https://github.com/nostr-protocol/nips/blob/master/01.md#from-relay-to-client-sending-events-and-notices looks like I made up the payment-required OK reponse but in the examples shown in https://github.com/nostr-protocol/nips/blob/master/11.md#pay-to-relay the user has to visit a page to pay upfront for publishing on the relay, nothing about pay per event is specced afaict. I suspect no one has done this (yet).
I see. When you have a #communikey that can publish messages, I'm wondering if we'll even need relays to respond in rich ways. Since the key pair can do it for them (and for the blossom server, mint, etc...)