We are seeing a cross-app session-isolation issue involving DeviceAccess / AccessorySetupKit and Accessory Notifications.
Setup: Garmin Connect owns an authorized Forerunner 745. Our app owns an Amazfit Active 3 Premium and an Amazfit Bip Max. Both Amazfit devices have working NotificationsForwarding DAExtensionSession instances.
Reproduction: Keep notification forwarding working for the Amazfit devices, then forget the Garmin Forerunner 745 in iOS Settings > Bluetooth.
DeviceAccess correctly removes only the Garmin device and emits DeviceLost for Garmin DeviceID C175AA77-... (com.garmin.connect.mobile). In the same millisecond, usernotificationsd invalidates two unrelated NotificationsForwarding sessions:
CID 0x2D07001D, DeviceID 13D01E46-..., BundleID com.huami.watch CID 0x2D07001C, DeviceID D86C37A0-..., BundleID com.huami.watch
The second session belongs to Bip Max. About four seconds later, notifications fail with:
post() failed: no connection hasExtensionSession: false
Bip Max remains Authorized and BTPaired, and its DADevice and notification capability remain present. Only its usernotificationsd-held NotificationsForwarding DAExtensionSession is lost. usernotificationsd also logs AccessoryNotifications.AccessoryError Code=5 while clearing the Garmin accessory record.
Should DeviceLost ever invalidate NotificationsForwarding sessions with a different DeviceID and owning app? Is there a supported way to rebuild the missing session without removing and re-authorizing the retained accessory?
Timestamp: 2026-08-31 14:08:46.973 local time. Full identifiers, tokens, and logs are omitted; we can provide a sysdiagnose and log archive through Feedback Assistant.