Now that we have a much-improved Special:Notifications page where we can go to view historical notifications, can we get a button to "clear all read notifications" from the Notifications Pane? I currently have a month's worth of read Flow notifications in my pane, and it makes for a pretty long list—currently about 3x the height of my browser window. I don't need these anymore; if I want to see who pinged me three weeks ago, I can go to the Notifications page.
Topic on Talk:Notifications
The panel(s) always list a maximum of 25 notifications (including various combinations of bundled, read, and unread, but prioritizing unread).
If I understand correctly, you want a way to remove all read notifications from the panel(s), effectively like an email client's "archive" functionality.
That seems like a reasonable feature-request, though the required UI would add additional complexity, which might be considered undesirable. I suggest you file it as a phab task, but I would guess it would be triaged as lowest priority for staff-development time. HTH.
Sounds reasonable. Thanks, @Quiddity (WMF)