In bug 1129470 I created a realtime notification system as a MVP. There are a few more features I'd like to implement in this. I'm filing this so they don't get forgotten. I had intended to do these as part of the original bug, but we needed to get that one landed, and these were not blockers * RealtimeRegistration objects should expire after some time. Maybe a few days. * RealtimeRegistrations that are not responded to should expire quickly. In particular, if a realtime notification is sent, and no one checks what happened within a few minutes, we should assume the client has disappeared, and expire the registration. * When a RealtimeRegistration is registered, it should be able to specify a "since" time. All actions that already exist since that time should be sent immediately. This helps avoid race conditions with questions being asked between when a question was loaded and when a RealtimeRegistration is created.