Feature
presence sensing
Headless nodes in a room hear the Bluetooth signal of visitors' phones and turn where people stand into control values for a patch.
Runs on:
Presence sensing uses several nodes as anchors. Each hears the phones near it, the nodes share what they heard, and each works out where the visitors are.
A patch declares where its anchors stand and wires the result like any other control. The presence example walks a figure around a triangle of anchors and pans it across four speakers.
The nodes read only what a phone already broadcasts to any receiver in range. Phones change that address about every 15 minutes, the presence code writes none of it to disk, and a patch sees a visitor as a short-lived id, never as a person. A visitor who turns Bluetooth off drops out within about 6 seconds.