Every uncaught error in a Flutter app lands on the same sink — with a severity floor so a phone on a metered connection is not billed for telemetry nobody reads.
runGuarded wires FlutterError.onError, PlatformDispatcher.onError, the zone's own handler and Isolate.addErrorListener to one reporting function. Anything less means a class of crash never reaches the logs.
The guarded zone
Only records at or above the floor are exported. An error or critical record brings the records that preceded it along as one breadcrumb record, so volume scales with faults, not with taps.
The export floor
Android's ApplicationExitInfo and JVM handler, iOS's MetricKit and NSException handler, read on the next launch over one Pigeon channel and exported as FATAL records that name, when known, the build and screen that died.
Native crashes
start() never throws, safely() swallows instrumentation that would, and the observers are only built when the SDK is up. A failed span costs a span, never a feature.
Failure isolation
otel_zone was extracted from the Vaam Store mobile app, where all of it was measured against a real collector and a real prepaid network in Cameroon. Every default in the package is the value that app ships, and the reasoning for each lives in the doc comment next to it.
The number that shaped it: 7,715 records off one set of release builds, and 96.5% of them chatter — one record per provider initialisation, per provider state change, per navigation. A cost that scales with how much someone uses the app, paid on a prepaid metered connection. The export floor is the answer, and the rest of the package exists so the floor can be trusted.
final OtelZone observability = OtelZone(
const OtelZoneConfig(
serviceName: 'my-app',
endpoint: 'http://localhost:4318',
),
);
Future<void> main() => observability.runGuarded(() async {
WidgetsFlutterBinding.ensureInitialized();
await observability.start(serviceVersion: '1.2.3');
runApp(const MyApp());
});That is the whole contract: build the OtelZone at the top level, open the zone, start the SDK inside it, run the app. Getting started covers installing it and wiring the observers.
Not on pub.dev
otel_zone is published as a Git dependency pinned to a commit (publish_to: 'none' in its pubspec.yaml). It is MIT-licensed.