One feature I miss in PB is the ability to list all thoughts that link to a particular thought. Obviously, it's easy to see thoughts that link to a given thought via a regular link - we can see that on the plex. However, if some thoughts link to another thought via a URL (brain://...) it's not possible to report on that. It would be good to have a way of seeing all thoughts that reference another thought both through regular links and URLs.
One reason why such functionality would be useful is to avoid a situation when I delete a thought and in the process break several links in other thoughts that point to the deleted thought. Ideally, I'd love to have an option in preferences where on trying to delete a thought that's linked to via a URL from other thoughts I'd get a warning "This thought is referenced from 5 other thoughts [list here..]. Deleting the thought will break links in these thoughts. Are you sure you want to do this?" Or something to this effect.