Fix trace ID mismatch in Sentry

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 - Span ids not re-generating for headers created from scope ([#3051](https://github.com/getsentry/sentry-dart/pull/3051))
 - `ScreenshotIntegration` not being added for web ([#3055](https://github.com/getsentry/sentry-dart/pull/3055))
+- `PropagationContext` not being set when `Scope` is cloned resulting in different trace ids when using `withScope` ([#3069](https://github.com/getsentry/sentry-dart/pull/3069))
 
 ### Enhancements
 

dart/lib/src/scope.dart

@@ -426,6 +426,7 @@ class Scope {
       .._transaction = _transaction
       ..span = span
       .._enableScopeSync = false
+      ..propagationContext = propagationContext
       .._replayId = _replayId;
 
     clone._setUserSync(user);

dart/test/hub_test.dart

@@ -779,6 +779,26 @@ void main() {
       expect(calls[2].scope?.user, isNull);
       expect(calls[2].formatted, 'foo bar 2');
     });
+
+    test(
+        'withScope should use the same propagation context as the current scope',
+        () async {
+      final hub = fixture.getSut();
+      late Scope clonedScope;
+      final currentScope = hub.scope;
+      await hub.captureEvent(SentryEvent(), withScope: (scope) async {
+        clonedScope = scope;
+      });
+
+      // Verify the propagation context is shared (same instance)
+      expect(
+          identical(
+              clonedScope.propagationContext, currentScope.propagationContext),
+          true,
+          reason: 'Propagation context should be the same instance');
+      expect(clonedScope.propagationContext.traceId,
+          currentScope.propagationContext.traceId);
+    });
   });
 
   group('ClientReportRecorder', () {

dart/test/scope_test.dart

@@ -411,6 +411,18 @@ void main() {
     expect(0, fixture.mockScopeObserver.numberOfSetContextsCalls);
   });
 
+  test('clone shares propagation context to maintain trace continuity', () {
+    final sut = fixture.getSut();
+
+    // Clone the scope
+    final clone = sut.clone();
+
+    // Verify the propagation context is shared (same instance)
+    expect(identical(sut.propagationContext, clone.propagationContext), true,
+        reason: 'Propagation context should be the same instance');
+    expect(clone.propagationContext.traceId, sut.propagationContext.traceId);
+  });
+
   group('Scope apply', () {
     final scopeUser = SentryUser(
       id: '800',