- A device credential that cannot be checked now (device store not running,
nonces unreadable) raises DeviceUnavailable: 503 over HTTP, and the
/flows/ws handshake and the tunnel stream accept and close with 1013.
1008 (a 403 before accepting) stays for a revoked or invalid one
- Device files are written through a temporary file, so a read mid-save no
longer looks like a deleted device
- The first report turns Touch friendly on only for a device paired since
pairings are noted (DeviceState.paired_at), so devices paired before keep
the switch they were given
- NodeDef reads `device`/`device_policy` from older clients as the worker
label, for a release
- Tests: transient vs revoked socket, the touch default, the old worker keys,
and a restart with a device node and a node_health rule sending no push