Had some discussion of how URL constraints should compare links. The word is "they should act the same as URL requirements, but with an eye towards changing both behaviors in the same way later". That's going to take some thought, because part of what I'm trying to do, is have comparisons between two different data types. I believe this is necessary for future-proofing, but I could be convinced otherwise.
Anyway, I'm going to be dividing my time between implementing these updates to my draft, and planning projects I want to work on. For now, it's late, I should wrap up.