Sense Presence Sensor R1

A millimetre-wave radar detects that somebody is in the room, not that somebody moved - so the light does not go out over the book. It reports which zone of the room is occupied, down to about half a metre, along with the ambient light level, which is what stops a lamp switching on at noon. Mounts on a ceiling or in a corner, runs from USB-C, and Matter over Thread means the response is immediate.