first implementation finished

app/lib/core/extension/result_async_extension.dart

@@ -0,0 +1,15 @@
+import 'package:exceptions/exceptions.dart';
+import 'package:riverpod/riverpod.dart';
+
+extension AsyncExtension<T> on Result<T> {
+  AsyncValue<T> toAsyncValue() {
+    return switch (this) {
+      Success(value: final value) => AsyncValue.data(value),
+      // TODO: Handle this case.
+      Failure(
+        error: final error,
+      ) =>
+        AsyncError(error.message, error.stackTrace ?? StackTrace.empty),
+    };
+  }
+}

app/lib/core/http_error_handler.dart

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+import 'package:exceptions/exceptions.dart';
+import 'package:http/http.dart';
+import 'package:universal_io/io.dart';
+
+ErrorMessage handleHttpError(
+  Exception exception,
+  StackTrace stackTrace,
+) {
+  return switch (exception) {
+    SocketException() => const ErrorMessage(
+        source: 'http',
+        message: 'Could not contact remote service',
+      ),
+    HttpException() => const ErrorMessage(
+        source: 'http',
+        message: 'Web request returned error',
+      ),
+    FormatException() => const ErrorMessage(
+        source: 'http',
+        message: 'Bad response format',
+      ),
+    ClientException() => const ErrorMessage(
+        source: 'http',
+        message: 'Could not contact remote service',
+      ),
+    _ => ErrorMessage.fromException(
+        exception,
+        stackTrace,
+      )
+  };
+}

app/lib/core/logger.dart

@@ -0,0 +1,3 @@
+import 'package:logger/logger.dart';
+
+final logger = Logger();

app/lib/core/providers.dart

@@ -0,0 +1,11 @@
+import 'package:go_router/go_router.dart';
+import 'package:kagi_bang_bang/core/routing/routes.dart';
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+
+part 'providers.g.dart';
+
+@Riverpod(keepAlive: true)
+GoRouter router(RouterRef ref) => GoRouter(
+      debugLogDiagnostics: true,
+      routes: $appRoutes,
+    );

app/lib/core/providers.g.dart

@@ -0,0 +1,24 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'providers.dart';
+
+// **************************************************************************
+// RiverpodGenerator
+// **************************************************************************
+
+String _$routerHash() => r'4ad45f430b1f43e427e21122d16bd761ca04ae0e';
+
+/// See also [router].
+@ProviderFor(router)
+final routerProvider = Provider<GoRouter>.internal(
+  router,
+  name: r'routerProvider',
+  debugGetCreateSourceHash:
+      const bool.fromEnvironment('dart.vm.product') ? null : _$routerHash,
+  dependencies: null,
+  allTransitiveDependencies: null,
+);
+
+typedef RouterRef = ProviderRef<GoRouter>;
+// ignore_for_file: type=lint
+// ignore_for_file: subtype_of_sealed_class, invalid_use_of_internal_member, invalid_use_of_visible_for_testing_member

app/lib/core/routing/routes.dart

@@ -0,0 +1,43 @@
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:kagi_bang_bang/features/search_browser/presentation/screens/browser.dart';
+import 'package:kagi_bang_bang/features/settings/data/repositories/settings_repository.dart';
+import 'package:kagi_bang_bang/features/settings/presentation/screens/settings.dart';
+
+part 'routes.g.dart';
+
+@TypedGoRoute<KagiRoute>(
+  path: '/',
+)
+class KagiRoute extends GoRouteData {
+  KagiRoute();
+
+  @override
+  Future<String?> redirect(BuildContext context, GoRouterState state) async {
+    final hasKagiSession = await ProviderScope.containerOf(context)
+        .read(settingsRepositoryProvider.future)
+        .then((value) => value.kagiSession?.isNotEmpty ?? false);
+
+    if (!hasKagiSession) {
+      return SettingsRoute().location;
+    }
+
+    return null;
+  }
+
+  @override
+  Widget build(BuildContext context, GoRouterState state) {
+    return const KagiScreen();
+  }
+}
+
+@TypedGoRoute<SettingsRoute>(
+  path: '/settings',
+)
+class SettingsRoute extends GoRouteData {
+  @override
+  Widget build(BuildContext context, GoRouterState state) {
+    return const SettingsScreen();
+  }
+}

app/lib/core/routing/routes.g.dart

@@ -0,0 +1,56 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'routes.dart';
+
+// **************************************************************************
+// GoRouterGenerator
+// **************************************************************************
+
+List<RouteBase> get $appRoutes => [
+      $kagiRoute,
+      $settingsRoute,
+    ];
+
+RouteBase get $kagiRoute => GoRouteData.$route(
+      path: '/',
+      factory: $KagiRouteExtension._fromState,
+    );
+
+extension $KagiRouteExtension on KagiRoute {
+  static KagiRoute _fromState(GoRouterState state) => KagiRoute();
+
+  String get location => GoRouteData.$location(
+        '/',
+      );
+
+  void go(BuildContext context) => context.go(location);
+
+  Future<T?> push<T>(BuildContext context) => context.push<T>(location);
+
+  void pushReplacement(BuildContext context) =>
+      context.pushReplacement(location);
+
+  void replace(BuildContext context) => context.replace(location);
+}
+
+RouteBase get $settingsRoute => GoRouteData.$route(
+      path: '/settings',
+      factory: $SettingsRouteExtension._fromState,
+    );
+
+extension $SettingsRouteExtension on SettingsRoute {
+  static SettingsRoute _fromState(GoRouterState state) => SettingsRoute();
+
+  String get location => GoRouteData.$location(
+        '/settings',
+      );
+
+  void go(BuildContext context) => context.go(location);
+
+  Future<T?> push<T>(BuildContext context) => context.push<T>(location);
+
+  void pushReplacement(BuildContext context) =>
+      context.pushReplacement(location);
+
+  void replace(BuildContext context) => context.replace(location);
+}