After the cat has been trained to avoid the shelf or desk, you can remove the foil.
I personally recommend motion-detecting air spray cans, I didn't want the cat to feel punished by me, he just needs to be redirected. Therefore I opt for these as a deterrent, since it is both effective and an action I undertake from the cat's view. I think he hates it because of the hiss, but the air spray itself might play a role.
And they might turn you into the Freakazoid
Maybe add a 1999 or 2000 datestamp to this (it won the https://en.wikipedia.org/wiki/List_of_Ig_Nobel_Prize_winners... Ig Nobel prize in Computer Science in 2000...)
Ultimately all this does is incentivize cats to type more accurately when inputting malicious commands
> Even while you use your other software, PawSense constantly monitors keyboard activity. PawSense analyzes keypress timings and combinations to distinguish cat typing from human typing.
grebc•1h ago