Maybe a cool feature would be if it didn't unlock automatically, but put it in "unlockable" mode, and would unlock when you knocked on it. You would still have

Maybe a cool feature would be if it didn't unlock automatically, but put it in "unlockable" mode, and would unlock when you knocked on it. You would still have the convenience of unlocking automatically (if your hands are full, use your knee or something), and it wouldn't unlock when you're in the house