look ahead

lib/widgets/shell_tab_scope.dart

@@ -0,0 +1,27 @@
+/// Provides the active bottom-nav tab index for [MainShell].
+library;
+
+import 'package:flutter/material.dart';
+
+class ShellTabScope extends InheritedWidget {
+  const ShellTabScope({
+    super.key,
+    required this.index,
+    required super.child,
+  });
+
+  final int index;
+
+  static int of(BuildContext context) {
+    final scope = context.dependOnInheritedWidgetOfExactType<ShellTabScope>();
+    assert(scope != null, 'ShellTabScope not found');
+    return scope!.index;
+  }
+
+  static int? maybeOf(BuildContext context) {
+    return context.dependOnInheritedWidgetOfExactType<ShellTabScope>()?.index;
+  }
+
+  @override
+  bool updateShouldNotify(ShellTabScope oldWidget) => index != oldWidget.index;
+}