pg_notify and the socket fan-out are not durable, so an offline phone used to miss a trigger forever and no-auto-stop would leave it ringing at nobody. Write one ledger row per enabled subscription in the trigger transaction, replay what a subscription still owes on every socket connect, and clear a row only on an explicit ack (live socket ack or ackAlarm); alarmStatus is a read-only check-in that answers 409 ERR_ALARM_TRIGGERED_OFFLINE with the missed frame. Ack is idempotent, and a destroyed alert cascades its debt away so a client is never told it missed an alarm that no longer exists.
device_id is a stable pseudonymous idempotency key, not a credential; a database dump should not be a usable list of device identifiers. Hash every caller-supplied value before it reaches the table, keep raw values out of logs and subscription views, and migrate existing rows with the identical SQL encoding.
An alert now rings from trigger until the owner disarms it; a subscriber silences only its own device. The owner instead sets a persistence cap (default 24h, hard cap 14 days) and the sweeper destroys expired alerts. Disarm ends an armed alert too, and every ending (delivered, expired, disarmed, deleted) converges on the one destruction path so their event-log reasons cannot drift.
The subscribe token is minted once per alert and lives as long as it does; subscribers are never evicted, so the rotation counter had no reader. Drop token_version from the schema and stop serialising tokenVersion on the wire. The QR payload is now built from alert id + token only, which also makes it instance-relative.
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