So… This is a thought experiment, right? How to get home automation geeks to design almost anything? Because there is no possible way that it would make sense to have a siren go off while you are asleep in order to keep your cat off the sofa. Just sayin’…
If you’ve spent any time with SmartThings, you should already know how to set up different triggers for different smartapps. But if you’re brand new to it, take a look at the following FAQ (this is a clickable link)
If in fact there is a serious question here and you have a couch that you watch the cat to stay away from when you are not in the room, and you don’t want to use the usual sprays because you do want the cat to sit on the couch with you when you are in the room, then by far the simplest thing is just to shut the cat out of the room.
If you live in a studio apartment and it’s just not possible to shut the cat out of the room, The most important thing to know is most cats will choose the highest available sleeping place. A tall cat tree or a “cat window perch” Will solve the problem in most households, as the cat will usually choose that instead of the couch.
We use both at our house. The following is our cats’ favorite window perch design, but there are many styles to choose from.
https://www.amazon.com/Window-Creative-Suction-Lounger-Cushion/dp/B076BPCZX7/
And this proved to be a surprisingly sturdy cat tree at over 5 feet tall. We have two cats, and when we put this near a window, both preferred it to pretty much anything else. Parts of the posts are wrapped with rope which makes a good scratching area as well.