I fixed this today, with a little sleeve and ten minutes' work. It took me longer to open the primer and glue cans, actually -- I had to take them to my mother's house, since my pliers are sitting in the port in San Juan awaiting loading.
Emboldened by my success with the sleeve, I replaced a tee, put in a ball valve, and spliced in another sleeve, and that should take me to the downstairs half-bath and a hose tap outside. Tomorrow, after it's all had time to set, I'll test it for the first time, and hey -- I may be able to start cleaning!
In other news today, I got my third carpet out and two more windows open. The air really is getting better in the house, step by step.
A word to the curious -- if you were expecting breakneck speed, you will be sadly disappointed. I have to keep up with the paying work first. My goal is to do at least one task per day with The House, to keep the momentum rolling. This week is just plumbing and cleaning, and getting to know the property. Next week, who knows?