State restoration

Because raku(...) is a standard RouterConfig, the navigation location is restored across process death for free — just give MaterialApp.router a restorationScopeId:

MaterialApp.router(restorationScopeId: 'app', routerConfig: router);

Flutter saves the current RouteInformation and re-feeds it to a fresh delegate on restart, which reconstructs the stack from the URL — so a user who is killed deep in the app returns to the same screen (the active path; inactive tabs restore to their initial route, as with a cold link). Verified end-to-end with restartAndRestore, including a negative case without restoration.

Per-screen widget state

To restore a screen’s own widget state (a half-typed form, a scroll offset), use Flutter’s RestorationMixin in that screen and give its page a restorationId via a custom pageBuilder — the hook is plumbed through RakuPage. The router restores which screens are shown; each screen restores its own contents.