It took about ten minutes’ easy work to swap out the busted switch for a new one. The most difficult parts of the whole thing were figuring out which breaker that room’s wired to, so I could pull it and get a dead circuit to work with, and trying to work against gravity to pull three wires into place where I could get a wire nut clamped on them all.
And I’m sure T will be pleased that she doesn’t have to pee in the dark any more.