I have an idea where I have something like a FOCUS tag that I can apply to tasks that need special attention.
However, I want to make it so that only 3 tasks can actually be tagged with FOCUS at a time. If I try to tag a fourth with FOCUS, I should just get an error. So in order to apply a FOCUS tag, the count of currently FOCUS-tagged tasks should be <3, otherwise I'll have to untag one.
Any idea on how to get started on doing this?