As user I’ve seen Spotlight implementations for document based apps (usually just using NSUserActivity), but the problem is that they usually duplicate results. You get one result from Files and then another one from the app’s index.

Also keeping the index up-to-date seems hard, since I can delete files outside the app, but the app’s index still contains it: I have to start the app, to get the index updated. I’m curious how you guys can solve this for MindNode.