She's making an effort to spend time with you, you ought to be asking why if this is new behaviour.
Game plan:
When she comes to smoke and talk tell her you were just about to take a break and ask if she wants to join you on a walk, if she stays in your garage after the walk, the next time she does this take a lunch or snack break after the walk and eat in the kitchen, when you are finished eating declare it is time for you to get back to work.
You will have checked her "spend time with hubby" box off for the day, and walked her through enough doors to tire her a bit and make her forget her train of thought without blowing her off or disgusting her.
You will have checked her "spend time with hubby" box off for the day
Maybe she just has trouble concluding a task? Your tips help make a clear end to the visit. For example some people have trouble ending hanging out with someone, and keep dragging it on and on.