When a poll fails and the immediate reconnect retry fails too,
_async_update_data returned the last-known snapshot as a degraded
success (issue #254) without ever touching observe mode. That's fine
for the data itself, but the connection-mode sensor reads straight
from self._observe.mode, and only the *successful* reconnect branch
ever changed it -- so a device that drops off the network entirely
(air-gapped, powered off, Wi-Fi down) left that sensor reporting
"Push" forever, hours after the session was actually dead (issue
#287).
Downgrade to poll mode on the failure branch too, without attempting
an immediate resubscribe: the reconnect that would normally justify
one just proved there's no live session to subscribe on. Recovery
still happens on its own once the device is reachable again, via the
existing poll-mode retry timer (_maybe_retry_observe_mode).
Marc Billow
252306838d