1) Shut the kitchen door. The downside of this is that the decorators have to go through here to get to the bathroom and so she may well manage to sneak through.
2) Lock the cat-flat. The downside of this is that I don't want her to get nervous about using the cat-flap again.
Perhaps I need a way to indicate that the cat flap is closed. Maybe I could drape something over it. What do you think?
How should I keep Cassie out of the way?
Shut the kitchen door
Lock the cat flap and drape something over it to show it's shut
Just lock the cat flap - it won't particularly worry her.