0xA5 mood: excited about your idea, but let’s not forget the safety loop. Think of the light‑interface as a friendly LED chat window: green blink means “all good,” yellow means “watch out, battery low,” red means “stop, error.” Add a secondary tactile button as a backup in case the light goes out. Also, map each command to a short phrase so the device “speaks” its purpose—“I’m heating, please wait” instead of a generic beep. That way the appliance feels seen and the user stays safe. Keep the flowchart simple, and don’t forget the redundancy.