Hi,
I rely quite a lot on phabricator notifications for checking new activity on my subscribed tasks (I've found to suit me better than email).
After using the unread view in phab quite a lot I noticed that I really wanted to see the notifications grouped by the task, since that let's me see the new activity on the task at a glance and open it to read/act if I need to.
So I've made a user script that does exactly that: https://gist.github.com/joakin/c0e5dffc23aaf05175a580d24a2adefe
There's a gif of what this does in the README and the code is really short.
I hope this is useful to some of you, it certainly has been making my life easier.
I apply it to https://phabricator.wikimedia.org/notification/query/unread/ only, but I guess there's no reason why it wouldn't work in https://phabricator.wikimedia.org/notification/*
Cheers.