What a nice build and documentation, you've really put a lot of thought and useful options into this project, thanks for that.

Hmmm, what's your use case for the Armed home mode?

I'd likely forget it, and open a window or door triggering the alarm.

Water sensor support is a great idea, as I've had a couple of old water heaters fail in the past, nice addition.

I have a Raspberry Pi 3+ sitting around doing nothing, so maybe this is a project for next winter.

edit: Just saw your Kids traffic light, what a fun project to teach children about traffic signals.