Field check: two phones, two trackers

The third generation went into a field check with two trackers and two phones, Android and iOS. Each tracker owns one Firestore document, where the first generation searched a shared Realtime Database list for its own entry. It listens there for commands (light, voice, reboot) and writes battery, temperature and a timestamp back every five seconds; position comes from the modem's GPS.

The map showed a fix on a real street, and both phones showed the same state. The app calls a tracker online only if its timestamp is under fifteen seconds old: a device that reports only on change cannot tell you it is dead, a heartbeat can. Three iOS test builds were archived that afternoon.