Write a unit test to prevent future key droppings.

Now I didn’t drop them but forgot to even bring them..

Just execute `make building` again and you should get new keys generated.

Right. Just regenerate the keys and the house, then just delete the unneeded house. Storage is cheap.

(The actual unit test merely confirms that dropping the keys in one highly specific way is now impossible. The keys cannot fall from between your fingers because the code now mandates that you wear mittens)

When the regression is handed off to QA, they find that it's still possible to drop keys when: the keys weigh 100 tons, there are thousands of keys, there is no keyring, the keys are actually marbles, or the keys are covered in oil. They also find that when no keys are present initially, one blank key spontaneously appears out of thin air.

When the new anti-key-dropping code ships to users, they find they can no longer put down any singular held objects.

The universe blue screens cause those keys were never supposed to be dropped

I think the typical software solution is to make hundreds of copies of your keys and stash them everywhere you might need them in advance.

Denormalization.