Have an URL know which file it produced

[Zweibach]

I've been doing a lot of dupe work lately and sometimes I have to look up the source to double-check things. A problem arises when you're trying to check a file that you've already done a some dupes for so it has a lot of attached URLs since I move them to the better copy.

I would like it if an URL could in some way indicate that "Yes, I am the URL that produced this file" so you knew which one is correct. Perhaps also some indication that an URL was from a lesser copy.

It would also be useful if this URL then got placed at the top of copy-url lists and the like, or the default copyable URL.

Perhaps also a job to verify URL-file associations, low-priority since it'd require the downloading and hash-checking of the file again.