Archive Completed Tasks

In our workflow, we want to show completed tasks without letting the list grow indefinitely.

I think it would be very useful to be able to archive completed tasks (which would hide them from view), while unarchived completed tasks could be left visible.

Then, an automation would be handy that would allow us to archive tasks completed X days ago (e.g., Archive all tasks marked complete greater than 7 days ago).

PS - Trello does this well.