In most chat platforms, @mentioning serves a dual purpose. It is a request for someone to view a message at some point, and it can also be a request for attention immediately. Unfortunately, @mentions always trigger notifications as though the latter is true, even when it is not.
It would be really cool if we could craft a UX around separating the urgency of your request for someone's attention from the request itself. Imagine that @mentions had a "deadline" of sorts that could be set anywhere in the range "ASAP",1hour,2hour,4hour,8hour,24hour, 3days,"whenever" (just some examples, actual time windows can be whatever).
When an @mention is received, the local client can decide whether/how to notify based on the deadline set on it. As a first heuristic, a visual cue could be displayed in the UI immediately, but notifications need not be sent out until 3/4ths of the deadline has elapsed.
We could tie this in with #123 and allow users to express public limits on how many notifications they are willing to receive from an individual within a period of time. Clients could warn users if they've urgently @mentioned someone too often (such that it will no longer trigger notifications).