Briar: test offline communication between real devices

Set up Briar on two or more test devices and exchange messages while connected, then deliberately lose internet connectivity. Check what still works over the transports available to those devices and how messages synchronize when a connection returns. Rehearse adding or replacing a device.

A security-focused messenger must fit the users' threat model and habits. Verify contact authentication, backup or recovery limitations, and the devices people actually carry. Do not infer protection from the app name alone; test the exact communication path.