Thread:Talk:Echo (Notifications)/Bundling and expiry

I think we ought to consider notification expiry as an optional attribute for notifications as well. This would certainly be helpful for notifications about things which are likely to become irrelevant soon. The primary use case here would be any kind of "system messages" (the types of things we might use CentralNotice for). But it might also be an alternative to bundling for high-frequency notifications about watchlist updates, talk page responses, etc. I'm not sure how useful a bundled "There are 345434 edits to 3433 pages on your watchlist" notification is.