Back at the root was calling SystemNavigator.pop(). That is not "background
the app": on Android it calls finish() on the activity, which tears down the
Flutter engine and drops the radio connection. Backing out and reopening
therefore landed on a disconnected radio needing a fresh connect. Wrong call
for the job, and worse than the behaviour it replaced.
Backgrounding without finishing needs moveTaskToBack, which has no Flutter
equivalent, so it goes over a method channel:
- MainActivity exposes meshcore_open/app_lifecycle with a moveTaskToBack
method, alongside the existing USB channel.
- AppBackgrounder wraps it and is a no-op off Android, where programmatic
backgrounding either does not apply (desktop windows close by their own
chrome) or is forbidden (iOS). On those platforms back at the root stays
unhandled rather than doing something destructive.
- AppShell awaits it instead of calling SystemNavigator.pop().
The activity stays alive, so the connection survives and reopening returns to
where the user was.
flutter analyze clean, dart format clean, 469 tests pass.
Strycher
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