The server read each Bluetooth device every 60 seconds, and each read is one scan and one connection. An adapter that fails after many connections had no way to get fewer of them.
--bluetooth-interval sets the wait after a good Bluetooth read, and the default stays at 60 seconds. Clients receive the last read during the wait. A failed read still tries again after 60 seconds, or after the interval for a shorter one.
The polling threads are daemon threads, so a stop ended the server in the middle of a Bluetooth read. The read got no disconnect, and the adapter kept an open connection or a scan in progress.
The server now sets the stop event at exit, closes its socket, and waits at most 20 seconds for the polling threads. A Bluetooth read that sees the stop event cancels its current step, disconnects, and returns. A read that waits for the adapter does not connect after a stop.
A failed JBD read retried forever inside a client request and blocked every other device and client. The server now starts one polling thread for each device, and a request returns the last snapshot. Only the first request after startup waits, until each device completes one read attempt.
One lock makes sure that only one Bluetooth collection runs at a time. A serial BMS retries a failed read after 1 second and keeps its last snapshot for 30 seconds. An error in a collection does not end the polling of that device.
Serial paths and collector interfaces remain compatible. Bluetooth polling uses a 60-second cache and backoff. Offline Bluetooth devices no longer retry forever inside a client request. Invalid device specifications do not echo account IDs.
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