Design a light with an ambient light sensor that automatically turns on the light when it becomes dark and turns it off when it becomes light. This part is simple: many products already do this.
Fancier than that: a human can manually override the switch, turning the light off despite it being dark: perhaps it is time to sleep, or the human is leaving the room. However, the manual override is not permanent. The overridden light turns back on after another day-night cycle or light-dark cycle.
What should be the behavior if a light-dark cycle happens because of another light in the room has been turned on then off? I think it should behave as if a day-night cycle happened: at least that is predictable and easy to understand.
The light automatically switches itself off when it becomes light. This too can be manually overridden if the user wants the light on even if it is already light. The manual override expires similarly after a dark period. There might be a problem with a passing shadow on the light sensor being mistaken for a dark period.
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