I am interested first in persistent backlogs -- do you know an IRCd that does that? I am sure it couldn't be implemented client-side. I remember "SILC" which

I am interested first in persistent backlogs -- do you know an IRCd that does that? I am sure it couldn't be implemented client-side. I remember "SILC" which is not IRC, but if I remember correctly it had this. Mainly when you join a room, you should not get tabula rasa. You enter into some context, and if the last message was posted 4 days ago, your context starts 4 days ago, and the datestamps all reflect this. There are other features of Slack that make it worth using, but this is the one thing I don't know if IRC can support at all, that I see every other serious chat system doing.