Windchimes

Chimes that ring to the rhythm of your own typing.

Work normally and a breeze builds over the rack; stop and the air settles back to stillness inside a minute. The only signal is a single yes-or-no timing check twice a second: there are no input hooks of any kind anywhere in this program, so it can prove it never sees a keystroke. Real local weather is an optional extra, off until you switch it on and type a place: once it's on, actual wind there sets the baseline breeze while your own typing still adds the gusts, and only a city-level rounded coordinate ever goes out, to Open-Meteo, at most once an hour. Bamboo, glass, brass, and shell sets unlock as lifetime listening hours add up.