I think what I did was make a badge that was awarded when I liked the thing assignment. I could then use those badges in a script that generated grades for the assignments.
Do you think it would be enough to use the like button for that (for some group or category owner) or does it need to be a different button?
Perhaps something like Retort - a reaction-style plugin for Discourse is close to what you want. I’m not sure if it’s possible to limit who can make retorts, but even if not, you should be able to hide the ability to respond with CSS.
So the “resolved” state is something that the original Poster and a Special Person (admin, group member, maybe someone who “owns” the category?) can toggle on and off? And, like “solved”, you’d tag one post as the “resolved” post and that would affect the topic’s Resolved state?
I think that Geoffrey is right that whether a topic has a “solved” post shuts down the conversation is a community norm (unless someone closes the topic).