Buddy (or Skeezix) has been mostly confined to the library, because he's still not sure he wants to share the house with Ruby. I've sat with him in the library a couple of evenings after Ruby has gone to bed in her kennel with the door open and he's wandered down the hall a bit, but not very far.
So I have a new plan.
Ruby has gone to bed. And the door to the library has been left open, although all of the bedroom doors upstairs are closed.
We'll see how this goes. (He's already ventured as far as the family room while we watched the end of the Cubs game.)