go-router

Drive NavigationBar.selectedIndex from StatefulNavigationShell.currentIndex, never from a setState field or a copy made in initState. Measured on Flutter 3.44.8 and go_router 18.0.2: which patterns drift on deep links, context.go and cross-branch pushes, why location-based indexes lie, and how to react to tab changes with didUpdateWidget.

go_router and auto_route both sit on top of Navigator 2.0, so the real choice is declarative URL routing vs code-generated typed routes vs hand-rolling the Router API. A decision matrix with config for each, and when raw Navigator still wins.

Build a persistent shell with nested routes using ShellRoute and StatefulShellRoute, then wire up path-based deep links that rebuild the full page stack. Full config for Android and iOS, plus the gotchas that break the back stack.