> One reason you might want a server is to have more expressive power than "if someone literally enters the room, turn on the lights". You might want to turn on the lights and run the AC a little before you predict people will arrive, for example.

Maybe, but that seems like a lot of work for little gain.

You probably don't actually have that much control over the AC in your rooms unless you have zoned heating and a lot of zones, regardless of how smart your sensors are.

Intent is a very important factor when answering the question "should the lights be on," I don't think you'll be able to predict that. For instance: if movement is detected in the bedroom at 2AM, should the lights come on? The answer is: a very strong maybe.