diff --git a/lib/screens/settings/atmos_diagnostics_screen.dart b/lib/screens/settings/atmos_diagnostics_screen.dart
index 8ecb7e9a..4935bb18 100644
--- a/lib/screens/settings/atmos_diagnostics_screen.dart
+++ b/lib/screens/settings/atmos_diagnostics_screen.dart
@@ -29,6 +29,7 @@ class _AtmosDiagnosticsScreenState extends State<AtmosDiagnosticsScreen> {
   Timer? _poll;
   Map<Object?, Object?> _status = const {};
   String? _activeMode;
+  bool _stopping = false;
 
   @override
   void initState() {
@@ -40,7 +41,7 @@ class _AtmosDiagnosticsScreenState extends State<AtmosDiagnosticsScreen> {
   @override
   void dispose() {
     _poll?.cancel();
-    _channel.invokeMethod('stop').ignore();
+    if (!_stopping) _channel.invokeMethod('stop').ignore();
     super.dispose();
   }
 
@@ -70,9 +71,18 @@ class _AtmosDiagnosticsScreenState extends State<AtmosDiagnosticsScreen> {
   }
 
   Future<void> _stop() async {
-    await _channel.invokeMethod('stop');
-    setState(() => _activeMode = null);
-    await _refreshStatus();
+    if (_stopping) return;
+    _stopping = true;
+    try {
+      await _channel.invokeMethod('stop');
+      if (!mounted) return;
+      setState(() => _activeMode = null);
+      await _refreshStatus();
+    } on PlatformException catch (e) {
+      if (mounted) showErrorSnackBar(context, e.message ?? e.code);
+    } finally {
+      _stopping = false;
+    }
   }
 
   Widget _testTile({required String mode, required IconData icon, required String title, required String subtitle}) {
diff --git a/test/screens/settings/atmos_diagnostics_screen_test.dart b/test/screens/settings/atmos_diagnostics_screen_test.dart
new file mode 100644
index 00000000..16e6aa7f
--- /dev/null
+++ b/test/screens/settings/atmos_diagnostics_screen_test.dart
@@ -0,0 +1,80 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:plezy/i18n/strings.g.dart';
+import 'package:plezy/screens/settings/atmos_diagnostics_screen.dart';
+import 'package:plezy/services/settings_service.dart';
+import 'package:plezy/theme/mono_theme.dart';
+
+import '../../test_helpers/prefs.dart';
+
+void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+
+  const channel = MethodChannel('plezy/atmos_probe');
+  final messenger = TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger;
+
+  setUp(() async {
+    resetSharedPreferencesForTest();
+    SettingsService.resetForTesting();
+    await SettingsService.getInstance();
+    LocaleSettings.setLocaleSync(AppLocale.en);
+  });
+
+  tearDown(() {
+    messenger.setMockMethodCallHandler(channel, null);
+  });
+
+  Future<void> pumpScreen(WidgetTester tester) async {
+    await tester.pumpWidget(MaterialApp(theme: monoTheme(dark: true), home: const AtmosDiagnosticsScreen()));
+    await tester.pump();
+    await tester.ensureVisible(find.text(t.settings.atmosTestStop));
+  }
+
+  testWidgets('unmounting during stop does not set state or stop twice', (tester) async {
+    final stopCompleter = Completer<void>();
+    var stopCalls = 0;
+    messenger.setMockMethodCallHandler(channel, (call) async {
+      if (call.method == 'stop') {
+        stopCalls++;
+        await stopCompleter.future;
+      }
+      return call.method == 'getStatus' ? <Object?, Object?>{} : null;
+    });
+
+    await pumpScreen(tester);
+    await tester.tap(find.text(t.settings.atmosTestStop));
+    await tester.pump();
+    expect(stopCalls, 1);
+
+    await tester.pumpWidget(const MaterialApp(home: SizedBox()));
+    expect(stopCalls, 1);
+
+    stopCompleter.complete();
+    await tester.pump();
+
+    expect(tester.takeException(), isNull);
+    expect(stopCalls, 1);
+  });
+
+  testWidgets('native stop failure is shown without escaping', (tester) async {
+    var stopCalls = 0;
+    messenger.setMockMethodCallHandler(channel, (call) async {
+      if (call.method == 'stop') {
+        stopCalls++;
+        throw PlatformException(code: 'stop_failed', message: 'Native stop failed');
+      }
+      return call.method == 'getStatus' ? <Object?, Object?>{} : null;
+    });
+
+    await pumpScreen(tester);
+    await tester.tap(find.text(t.settings.atmosTestStop));
+    await tester.pump();
+
+    expect(stopCalls, 1);
+    expect(find.text('Native stop failed'), findsOneWidget);
+    expect(tester.takeException(), isNull);
+  });
+}