As a slight amendment to point 1, if endTS/endUID describe a message from today, even though it's not the most recent message, when hitting "refresh", we may actually get new messages anyways.  So actually we may need to check if the timestamp corresponds to "today", and in that case use the logic too.  Which means a little bit of extra work in terms of calculating the change in its prior value and current value.  Or we could punt on that and just leave an XXX.