Well, it did need stitches, so vet was called, came out, gave me a heart attack by saying he thought she MIGHT have severed the extensor based on where the wound was and how deep it looked.
Once he got in there and had a good look/poke around, it was determined she had only lacerated the tendon, and it was essentially structurally still intact. His advice was to bandage for 10 days and then treat it like we usually treat an injury after that. We don't bandage unless there's NO other way to keep it covered, and usually, there are other ways. Human dressings work really well.
Anyway, she would NOT let us change her bandage. We got the first one off but could not get a fresh one on. So we dressed it like any other wound and stuck a tendon boot on her leg to support it, changing the boot out every 2-3 days. Come the 11 day mark we decided to see how she went without the boot. It was getting difficult to keep it on for more than a few hours at a time anyway - Magic has gotten quite proficient at getting boots off!
It's fully filled in and has a good bit of proud flesh at present which is being treated.
Today is day 19 and her leg looks like this, pre-cleaning [pic one is of inside of leg, pic two is of front]: