Oddbean new post about login | logout Cool. But ultimately it’s User A’s wallet that the funds are coming from? Via an invoice? Sorry, haven’t yet had a chance to read the docs.
To send a user needs to be created with an NWC and to receive they need to have a lightning address for getting an invoice. Users can also "receive" without a lightning address, and when they do add a lightning address all the pending payment requests will be sent out.