Silly #homekit automation. I've got an Inovelli #matter light switch with a programmable LED. I've set it to turn red when the front door is unlocked, and back to green when locked.
And it’s already paid off. We've been having some work done and had disabled automatic locking for the workers to be able to enter and leave without hassling with the lock. One day, we forgot to turn it back on when they were done, and I spotted the red light as I was headed to bed. Pretty handy, and it's all HomeKit native (no need for home assitant, etc.).







