fix: report a user-requested stop as stopped rather than failed

Stopping a test shuts down the control socket, so iperf_run_client() returns
-1 with "unable to send control message ... Broken pipe". That is the
expected consequence of the stop, not a fault, but the bridge read the
negative return as a failure — so pressing STOP left the UI showing
"Error (exit 1)" above a broken-pipe message.

The bridge now consults its own g_stop flag before classifying the outcome,
and the distinction travels up as Iperf3Result.stopped so the status line can
say "Stopped". A stop is reported with exit code 0: the run ended the way the
user asked it to.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

android/app/src/main/cpp/iperf_jni.c

@@ -251,8 +251,14 @@ static void iperf_cleanup_and_signal(JNIEnv *env,
     retire_test();
     free_argv(argv, argc);
 
+    /* A user-requested stop shuts down the control socket, so
+     * iperf_run_client() returns -1 with "Broken pipe" — expected, not a
+     * failure. Check g_stop so that path is reported as a stop, not an error. */
+    int user_stopped = stopped || g_stop;
+    g_stop = 0;
+
     /* Signal result to Java */
-    if (stopped) {
+    if (user_stopped) {
         signal_output(env, state, "[iPerf JNI] Test was stopped by user.\n");
     } else if (ret < 0) {
         char errbuf[256];

lib/data/services/iperf3_service.dart

@@ -54,9 +54,13 @@ class Iperf3Service {
   /// Whether the native layer reported an error during this run.
   bool _sawError = false;
 
+  /// Whether [stop] was called for the current run.
+  bool _stopRequested = false;
+
   /// Cancel any running test.
   Future<void> stop() async {
     if (!_isRunning) return;
+    _stopRequested = true;
     try {
       await _channel.invokeMethod('stopIperf');
     } catch (e) {
@@ -83,6 +87,7 @@ class Iperf3Service {
 
     _isRunning = true;
     _sawError = false;
+    _stopRequested = false;
     _outputBuffer.clear();
 
     final args = config.toCliArgs();
@@ -157,7 +162,10 @@ class Iperf3Service {
           completer.complete(
             Iperf3Result(
               rawOutput: _transcript(),
-              exitCode: _sawError ? exitCodeNativeError : 0,
+              // A user-requested stop is a normal outcome, not a failure.
+              exitCode:
+                  (_sawError && !_stopRequested) ? exitCodeNativeError : 0,
+              stopped: _stopRequested,
             ),
           );
         }

lib/domain/models/iperf3_result.dart

@@ -3,8 +3,13 @@ class Iperf3Result {
   final String rawOutput;
   final int exitCode;
 
+  /// Whether the run ended because the user asked it to stop, rather than
+  /// finishing its configured duration or failing.
+  final bool stopped;
+
   const Iperf3Result({
     required this.rawOutput,
     required this.exitCode,
+    this.stopped = false,
   });
 }

lib/ui/features/test_run/test_run_screen.dart

@@ -166,7 +166,10 @@ class _TestRunContentState extends State<_TestRunContent> {
                 final (String label, Color color) = switch (vm.state) {
                   TestRunState.idle => ('Ready', scheme.onSurfaceVariant),
                   TestRunState.running => ('Running…', scheme.primary),
-                  TestRunState.completed => ('Test complete', scheme.primary),
+                  TestRunState.completed => (
+                      vm.wasStopped ? 'Stopped' : 'Test complete',
+                      vm.wasStopped ? scheme.onSurfaceVariant : scheme.primary,
+                    ),
                   TestRunState.error => (
                       'Error${vm.result != null ? ' (exit ${vm.result!.exitCode})' : ''}',
                       scheme.error,

lib/ui/features/test_run/test_run_view_model.dart

@@ -39,6 +39,9 @@ class TestRunViewModel extends ChangeNotifier {
   /// Whether a test is currently in flight.
   bool get isRunning => _state == TestRunState.running;
 
+  /// Whether the most recent finished run ended because the user stopped it.
+  bool get wasStopped => _result?.stopped ?? false;
+
   /// Start a test with the given configuration.
   Future<void> runTest(TestConfiguration config) async {
     if (_state == TestRunState.running) return;

test/domain/models/iperf3_result_test.dart

@@ -11,5 +11,15 @@ void main() {
       expect(result.rawOutput, equals('Test complete'));
       expect(result.exitCode, equals(0));
     });
+
+    test('stopped defaults to false', () {
+      const result = Iperf3Result(rawOutput: 'x', exitCode: 0);
+      expect(result.stopped, isFalse);
+    });
+
+    test('stopped is preserved when set', () {
+      const result = Iperf3Result(rawOutput: 'x', exitCode: 0, stopped: true);
+      expect(result.stopped, isTrue);
+    });
   });
 }

test/ui/features/test_run/test_run_view_model_test.dart

@@ -120,6 +120,31 @@ void main() {
       await run;
     });
 
+    test('wasStopped reflects a user-requested stop', () async {
+      final mock = _MockIperf3Service(
+        onRun: (_) async => const Iperf3Result(
+          rawOutput: 'stopped early',
+          exitCode: 0,
+          stopped: true,
+        ),
+      );
+      final vm = TestRunViewModel(iperf3Service: mock);
+      await vm.runTest(const TestConfiguration(server: '192.168.1.1'));
+      // A user stop is a normal outcome: completed, not error.
+      expect(vm.state, equals(TestRunState.completed));
+      expect(vm.wasStopped, isTrue);
+    });
+
+    test('wasStopped is false for a run that finished on its own', () async {
+      final mock = _MockIperf3Service(
+        onRun: (_) async =>
+            const Iperf3Result(rawOutput: 'done', exitCode: 0),
+      );
+      final vm = TestRunViewModel(iperf3Service: mock);
+      await vm.runTest(const TestConfiguration(server: '192.168.1.1'));
+      expect(vm.wasStopped, isFalse);
+    });
+
     test('a second runTest while running is ignored', () async {
       final mock = _MockIperf3Service();
       final gate = Completer<Iperf3Result>();