Mentions of https://voxpelli.com/social/2016/07/76599/
The concept of task completion in IndieWeb also reminds me a little of the functionality GoodRead.com has for updating one's status on reading a book: Either I'm on page X of Y or I'm X% done with book. Eventually one completes the book. In their UI, they also present a completion bar with the percentage of the book that's read to give a visual indicator as well. I don't suppose there's any reason a webmention couldn't also include a percentage finished to add this piece of data.
Interesting ! Wondering how Tasks could receive the same type of "Yes,No,Maybe" like Events and perhaps use a similar approach to have "todo, done, ongoing" completion status? Assigning tasks to other users would need the ability to @mention another user/site to propose an assignation to someone else and some mechanism to know when the task is accepted by the user or not or fallback to non-assigned task if nobody take it.