Completing a single instance of a repeating task

Problem: I track lots of repeating events in Sandy. For example, I entered my Tuesday weights routine as "r upper-body and abs @fitness @weekly @todo". (I've tested this with and without the @todo tag, BTW; I just prefer to use @todo for everything that isn't a time-specific task.)

When I have finished the workout, I want to check it completed. However, I get a pop-up asking if I want to mark the entire series completed, and the only options are Yes or Cancel. Since this event repeats indefinitely, I certainly don't want to mark the whole series done! Past instances show up in my schedule and/or @todo list because Sandy thinks they're still active.

Idea: Please implement an additional option to select "this instance only" for actions (archive/edit/complete) on repeating events.