[IbrarIlyas]

The Navigator of every StatefulShellRoute branch is wrapped in a PopScope that
keeps the shell itself from being popped, for example by an iOS back gesture,
while the branch has an active sub-route.

Inactive branches stay mounted, so their PopScope stays registered as a pop
entry of the same enclosing route as the active one, and ModalRoute only allows
a pop if every registered entry allows it. Switching away from a branch that
still had a sub-route therefore suppressed the system back button for the whole
app: popRoute() reported the pop as handled without popping anything, so Android
never closed the activity.

The guard now only applies to the active branch. StatefulNavigationShell
publishes which of its branches is active through an ActiveBranchScope inherited
widget, and the PopScope depends on it, so canPop is also kept up to date when
the user switches branches without the route matches of a branch changing.
Behavior is unchanged for a plain ShellRoute, which has no enclosing
ActiveBranchScope.

Tests added to test/stateful_shell_route_system_back_test.dart, next to the
existing issue 120353 gesture tests: the issue's repro, back still popping the
sub-route once the branch is active again, and a per-branch canPop check
confirming the active branch still guards the shell. Also verified manually on
an Android 15 device.

Fixes flutter/flutter#193098

Replace this paragraph with a description of what this PR is changing or adding, and why. Consider including before/after screenshots.

List which issues are fixed by this PR. You must list at least one issue.

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[gemini-code-assist]

Code Review

This pull request introduces ActiveBranchScope, an InheritedWidget that tracks whether a subtree belongs to the currently active branch of a StatefulShellRoute. It updates _CustomNavigatorState and _BranchNavigatorProxy to utilize this scope, ensuring that only the active branch's PopScope can veto pops, which prevents inactive branches with active sub-routes from blocking system back navigation. Additionally, regression tests and a changelog entry are included. There are no review comments, so no further feedback is provided.

[elliette]

Thanks for the contribution! You haven’t completed all of the items in the PR checklist above, so I’m assuming this is a work in progress and am marking it as a Draft. Please review the checklist, updating the PR as appropriate, and when that’s complete please feel free to mark the PR as ready for review.

[gemini-code-assist]

Code Review

This pull request introduces ActiveBranchScope, an InheritedWidget that tracks whether a subtree belongs to the active branch of a StatefulShellRoute. This allows the PopScope of shell route navigators to only veto pops when their branch is active, resolving an issue where the system back button was ignored after switching branches. Regression tests and a changelog entry are also added. The review feedback recommends removing the generic type argument from the PopScope cast in the test file to prevent compilation errors on older Flutter versions.

[IbrarIlyas]

@elliette @ianloic @sethladd Checklist is done now, so this is ready for review. Its my first time 🙂

[IbrarIlyas]

Hi Flutter team,

I’m following up on this PR. I have addressed the review feedback, updated the test accordingly, and synced the branch with main.

The PR is currently waiting for the CICD label and tests to run. I would appreciate it if you could review the latest implementation whenever convenient.

Thank you for your time.

[IbrarIlyas]

can you guide me @Piinks what is the issue in this PR so that i can make sure to fix it.

[flutter-dashboard]

This pull request is not mergeable in its current state, likely because of a merge conflict. Pre-submit CI jobs were not triggered. Pushing a new commit to this branch that resolves the issue will result in pre-submit jobs being scheduled.

[Piinks]

Hi @IbrarIlyas, please refrain from tagging maintainers directly. This will be reviewed shortly.

[Piinks]

Can you also add this test in order to ensure coverage for preload: true?

Details

testWidgets(
  'Preloaded branch (preload: true) with deep initialLocation does not veto pop while inactive, and guards shell once activated',
  (WidgetTester tester) async {
    final router = GoRouter(
      initialLocation: '/home',
      routes: <RouteBase>[
        StatefulShellRoute.indexedStack(
          builder:
              (
                BuildContext context,
                GoRouterState state,
                StatefulNavigationShell shell,
              ) => Scaffold(
                body: shell,
                bottomNavigationBar: Row(
                  children: <Widget>[
                    FilledButton(
                      key: const Key('toHome'),
                      onPressed: () => shell.goBranch(0),
                      child: const Text('Home'),
                    ),
                    FilledButton(
                      key: const Key('toSettings'),
                      onPressed: () => shell.goBranch(1),
                      child: const Text('Settings'),
                    ),
                  ],
                ),
              ),
          branches: <StatefulShellBranch>[
            StatefulShellBranch(
              routes: <RouteBase>[
                GoRoute(
                  path: '/home',
                  builder: (BuildContext context, GoRouterState state) =>
                      const Scaffold(body: Text('Home Screen')),
                ),
              ],
            ),
            StatefulShellBranch(
              preload: true,
              initialLocation: '/settings/general',
              routes: <RouteBase>[
                GoRoute(
                  path: '/settings',
                  builder: (BuildContext context, GoRouterState state) =>
                      const Scaffold(body: Text('Settings Screen')),
                  routes: <RouteBase>[
                    GoRoute(
                      path: 'general',
                      builder: (BuildContext context, GoRouterState state) =>
                          const Scaffold(body: Text('General Screen')),
                    ),
                  ],
                ),
              ],
            ),
          ],
        ),
      ],
    );
    addTearDown(router.dispose);

    await tester.pumpWidget(MaterialApp.router(routerConfig: router));
    await tester.pumpAndSettle();

    expect(_branchCanPopValues(tester), <bool>[true, true]);
    expect(await tester.binding.handlePopRoute(), isFalse);

    await tester.tap(find.byKey(const Key('toSettings')));
    await tester.pumpAndSettle();
    expect(find.text('General Screen'), findsOneWidget);
    expect(_branchCanPopValues(tester), <bool>[true, false]);

    expect(await tester.binding.handlePopRoute(), isTrue);
    await tester.pumpAndSettle();
    expect(find.text('Settings Screen'), findsOneWidget);
    expect(_branchCanPopValues(tester), <bool>[true, true]);
  },
);

[IbrarIlyas]

Thanks for the review! I've updated the PR:

• Merged latest 'main' and resolved the conflict with [go_router] Expose Navigator clipBehavior on ShellRoute and StatefulShellBranch #12646 in 'builder.dart' (kept the new 'clipBehavior' argument).
• Annotated 'ActiveBranchScope' with '@internal'.
• Switched the test helper to a typed 'widgetList'.
• Added the 'preload: true' test. It passes with the current fix.

[Piinks]

LGTM thank you!

[Piinks]

Can you address the merge conflicts?

[IbrarIlyas]

Resolved the merge conflicts with latest main. Analyze and the go_router tests pass locally.

[elliette]

Thank you, LGTM!

[elliette]

(Note: Updated the branch to get #13544, which should fix the failures).