When there is a new echo event it is confusing, that the list show also up to four old events. It should be possible to mark events as 'archived'. A archived event will not be shown by default on the pop-up or on the special page, but it is possible to see it on the special page by a filter.
With this feature it easier to read a user talk message now and answer it later.
A event is marked as read when clicked on the diff link, but it does not mean, that you have answer/working on it. At the moment you have to keep in mind that the event needs a answer and when you have time than you can go to the list of events and search the relevant event.
When all done events can be archived, than it is easier to find events which are not done. This can be done as opt-in and than the event count shows a grey number of unarchived events in the list. New unread events still will give a red count.
You can compare this with a email inbox, where new unread messages are bold and get unbold when read the first time. When worked on it you can move it to a folder to archive it or delete the mail. Than you can use the inbox as a (big) todo list. (I know that other people never moving mails out of the inbox, but that is the current situation in echo and you can leave that unchanged).
Pin discussion - T73564: Allow marking Echo notifications as unread