I've been building up all sorts of sensors and actuators in my home - and i discussed this with my father who is a SCADA engineer (and looking to do the same to his house).
In previous post, i talked about querying the state of actuators (that's a fancy name for lightbulbs). Dad's very wise comment was: in SCADA systems, you don't ask the Lake Taupō control gate if it's opened. You ask the water flow sensors and the lake level sensors if there's water flowing and the lake level changing.
So, i shouldn't be asking "hey light bulb, did you turn on?". I should be asking "Hey light sensor under the bulb, is there light?"
I shouldn't ask only: "Wemo, did you turn the heater on?". I need to ask "temperature sensor, is the temperature rising in that room?"
And there in lies a small eureka moment in my automated home designs.