feat(auth): add registration, check-email and email-link screens

Implements KTO-01 criteria 1-4, 10 and 11 (client part).

Refs #1

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

app/lib/core/config/auth_config.dart

@@ -0,0 +1,9 @@
+/// Auth settings the client has to know. They mirror the server configuration.
+abstract final class AuthConfig {
+  /// Validity of confirmation and reset links (AUTH-CFG-07,
+  /// `GOTRUE_MAILER_OTP_EXP=3600`, see `docs/auth-konfiguration.md`).
+  ///
+  /// The text `authCheckEmailValidityOneHour` is only correct while this is
+  /// one hour; a test pins the value.
+  static const linkValidity = Duration(hours: 1);
+}

app/lib/core/platform/platform_info.dart

@@ -0,0 +1,14 @@
+import 'package:flutter/foundation.dart';
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+
+part 'platform_info.g.dart';
+
+/// `true` for the web app in a mobile browser (iOS or Android user agent).
+///
+/// Kept in one provider so that platform checks are not scattered over the
+/// UI; tests override it.
+@Riverpod(keepAlive: true)
+bool isMobileWeb(Ref ref) =>
+    kIsWeb &&
+    (defaultTargetPlatform == TargetPlatform.iOS ||
+        defaultTargetPlatform == TargetPlatform.android);

app/lib/core/platform/platform_info.g.dart

@@ -0,0 +1,63 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'platform_info.dart';
+
+// **************************************************************************
+// RiverpodGenerator
+// **************************************************************************
+
+// GENERATED CODE - DO NOT MODIFY BY HAND
+// ignore_for_file: type=lint, type=warning
+/// `true` for the web app in a mobile browser (iOS or Android user agent).
+///
+/// Kept in one provider so that platform checks are not scattered over the
+/// UI; tests override it.
+
+@ProviderFor(isMobileWeb)
+final isMobileWebProvider = IsMobileWebProvider._();
+
+/// `true` for the web app in a mobile browser (iOS or Android user agent).
+///
+/// Kept in one provider so that platform checks are not scattered over the
+/// UI; tests override it.
+
+final class IsMobileWebProvider extends $FunctionalProvider<bool, bool, bool>
+    with $Provider<bool> {
+  /// `true` for the web app in a mobile browser (iOS or Android user agent).
+  ///
+  /// Kept in one provider so that platform checks are not scattered over the
+  /// UI; tests override it.
+  IsMobileWebProvider._()
+    : super(
+        from: null,
+        argument: null,
+        retry: null,
+        name: r'isMobileWebProvider',
+        isAutoDispose: false,
+        dependencies: null,
+        $allTransitiveDependencies: null,
+      );
+
+  @override
+  String debugGetCreateSourceHash() => _$isMobileWebHash();
+
+  @$internal
+  @override
+  $ProviderElement<bool> $createElement($ProviderPointer pointer) =>
+      $ProviderElement(pointer);
+
+  @override
+  bool create(Ref ref) {
+    return isMobileWeb(ref);
+  }
+
+  /// {@macro riverpod.override_with_value}
+  Override overrideWithValue(bool value) {
+    return $ProviderOverride(
+      origin: this,
+      providerOverride: $SyncValueProvider<bool>(value),
+    );
+  }
+}
+
+String _$isMobileWebHash() => r'd287a0a13cb71abe06b3d01885723f1d3ac520b1';

app/lib/core/platform/url_opener.dart

@@ -0,0 +1,21 @@
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+import 'package:shuffle/core/logging/app_logger.dart';
+import 'package:url_launcher/url_launcher.dart';
+
+part 'url_opener.g.dart';
+
+/// Opens [uri] outside the app (browser). Returns whether it worked.
+typedef UrlOpener = Future<bool> Function(Uri uri);
+
+final _log = AppLogger('UrlOpener');
+
+/// The only place that touches `url_launcher`. Tests override this provider.
+@Riverpod(keepAlive: true)
+UrlOpener urlOpener(Ref ref) => (uri) async {
+  try {
+    return await launchUrl(uri, mode: LaunchMode.externalApplication);
+  } on Object catch (error) {
+    _log.warning('launchUrl failed: ${error.runtimeType}');
+    return false;
+  }
+};

app/lib/core/platform/url_opener.g.dart

@@ -0,0 +1,55 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'url_opener.dart';
+
+// **************************************************************************
+// RiverpodGenerator
+// **************************************************************************
+
+// GENERATED CODE - DO NOT MODIFY BY HAND
+// ignore_for_file: type=lint, type=warning
+/// The only place that touches `url_launcher`. Tests override this provider.
+
+@ProviderFor(urlOpener)
+final urlOpenerProvider = UrlOpenerProvider._();
+
+/// The only place that touches `url_launcher`. Tests override this provider.
+
+final class UrlOpenerProvider
+    extends $FunctionalProvider<UrlOpener, UrlOpener, UrlOpener>
+    with $Provider<UrlOpener> {
+  /// The only place that touches `url_launcher`. Tests override this provider.
+  UrlOpenerProvider._()
+    : super(
+        from: null,
+        argument: null,
+        retry: null,
+        name: r'urlOpenerProvider',
+        isAutoDispose: false,
+        dependencies: null,
+        $allTransitiveDependencies: null,
+      );
+
+  @override
+  String debugGetCreateSourceHash() => _$urlOpenerHash();
+
+  @$internal
+  @override
+  $ProviderElement<UrlOpener> $createElement($ProviderPointer pointer) =>
+      $ProviderElement(pointer);
+
+  @override
+  UrlOpener create(Ref ref) {
+    return urlOpener(ref);
+  }
+
+  /// {@macro riverpod.override_with_value}
+  Override overrideWithValue(UrlOpener value) {
+    return $ProviderOverride(
+      origin: this,
+      providerOverride: $SyncValueProvider<UrlOpener>(value),
+    );
+  }
+}
+
+String _$urlOpenerHash() => r'f5f1e650e073776595fac2981548a91f815c66ca';

app/lib/core/routing/app_router.dart

@@ -3,7 +3,7 @@ import 'package:riverpod_annotation/riverpod_annotation.dart';
 import 'package:shuffle/core/routing/app_routes.dart';
 import 'package:shuffle/core/routing/not_found_screen.dart';
 import 'package:shuffle/core/routing/redirect_source.dart';
-import 'package:shuffle/features/auth/presentation/auth_route_placeholder.dart';
+import 'package:shuffle/features/auth/presentation/auth_routes.dart';
 import 'package:shuffle/features/home/presentation/home_screen.dart';
 
 part 'app_router.g.dart';

app/lib/core/widgets/app_text_field.dart

@@ -27,6 +27,7 @@ class AppTextField extends StatelessWidget {
     this.suffixIcon,
     this.maxLength,
     this.showCounter = false,
+    this.counterText,
     this.inputFormatters,
     this.enabled = true,
     this.autofocus = false,
@@ -57,6 +58,11 @@ class AppTextField extends StatelessWidget {
 
   /// Shows a `n/max` counter (needs [maxLength]).
   final bool showCounter;
+
+  /// Optional text for the counter (e.g. "4/30"). Use it when the counted
+  /// unit differs from the default (graphemes of the raw text). Only shown
+  /// when [showCounter] is set.
+  final String? counterText;
   final List<TextInputFormatter>? inputFormatters;
   final bool enabled;
   final bool autofocus;
@@ -115,6 +121,7 @@ class AppTextField extends StatelessWidget {
             onEditingComplete: onEditingComplete,
             decoration: InputDecoration(
               suffixIcon: suffixIcon,
+              counterText: showCounter ? counterText : null,
               error: hasError ? AppFieldError(errorText!) : null,
               helper: !hasError && helper != null && helper.isNotEmpty
                   ? Text(

app/lib/features/auth/domain/email_link_request.dart

@@ -0,0 +1,19 @@
+import 'package:shuffle/features/auth/domain/email_link_type.dart';
+
+/// Parameters of a mail link `/auth/confirm?token_hash=…&type=…`.
+class EmailLinkRequest {
+  const EmailLinkRequest({required this.tokenHash, required this.type});
+
+  final String tokenHash;
+  final EmailLinkType type;
+
+  /// `null` if the token is missing or the type is unknown.
+  static EmailLinkRequest? tryParse(String? tokenHash, String? type) {
+    final parsedType = EmailLinkType.tryParse(type);
+    final token = tokenHash?.trim();
+    if (token == null || token.isEmpty || parsedType == null) {
+      return null;
+    }
+    return EmailLinkRequest(tokenHash: token, type: parsedType);
+  }
+}

app/lib/features/auth/presentation/auth_failure_texts.dart

@@ -0,0 +1,38 @@
+import 'package:shuffle/core/l10n/l10n.dart';
+import 'package:shuffle/features/auth/domain/auth_failure.dart';
+
+/// User-facing text of an [AuthFailure] (Spec #1 § 4.4, texts from
+/// `docs/design/auth-screens.md`).
+///
+/// `emailSendLimited` has no text of its own: screens treat it as success
+/// (F12) or convert it to `rateLimited` beforehand.
+String authFailureMessage(AppLocalizations l10n, AuthFailure failure) =>
+    switch (failure) {
+      InvalidCredentials() => l10n.authErrorInvalidCredentials,
+      EmailNotConfirmed() => l10n.authErrorEmailNotConfirmed,
+      EmailSendLimited() || RateLimited() => l10n.authErrorRateLimited,
+      WeakPassword(:final reasons) => weakPasswordMessage(l10n, reasons),
+      SamePassword() => l10n.authErrorSamePassword,
+      LinkInvalidOrExpired() => l10n.authErrorLinkInvalidOrExpired,
+      InvalidEmail() => l10n.authErrorEmailInvalid,
+      RegistrationRejected() => l10n.authErrorRegistrationRejected,
+      NetworkFailure() => l10n.authErrorNetwork,
+      Unexpected() => l10n.authErrorUnexpected,
+    };
+
+/// One sentence per distinct reason; an empty list gets the generic text.
+String weakPasswordMessage(
+  AppLocalizations l10n,
+  List<WeakPasswordReason> reasons,
+) {
+  final texts = <String>{
+    for (final reason in reasons)
+      switch (reason) {
+        WeakPasswordReason.length => l10n.authErrorWeakPasswordLength,
+        WeakPasswordReason.pwned => l10n.authErrorWeakPasswordPwned,
+        WeakPasswordReason.characters ||
+        WeakPasswordReason.unknown => l10n.authErrorWeakPasswordCharacters,
+      },
+  };
+  return texts.isEmpty ? l10n.authErrorWeakPasswordCharacters : texts.join(' ');
+}

app/lib/features/auth/presentation/auth_route_placeholder.dart

@@ -1,9 +1,8 @@
 import 'package:flutter/material.dart';
 import 'package:go_router/go_router.dart';
-import 'package:shuffle/core/routing/app_routes.dart';
 
-/// Platzhalter für Auth-Seiten, bis A2 bis A4 die Screens liefern. Ohne
-/// sichtbare Texte (keine hartkodierten UI-Strings).
+/// Placeholder for auth pages that 01b and 01c still deliver. Without visible
+/// texts (no hard-coded UI strings).
 class AuthRoutePlaceholder extends StatelessWidget {
   const AuthRoutePlaceholder({required this.routeKey, super.key});
 
@@ -14,27 +13,7 @@ class AuthRoutePlaceholder extends StatelessWidget {
       Scaffold(key: Key('auth_placeholder_$routeKey'), body: const SizedBox());
 }
 
-/// Routen der Auth-Seiten nach Spec #1 § 5.3. A2 bis A4 ersetzen die Builder.
-final List<RouteBase> authRoutes = [
-  _placeholder(AppRoutes.login, 'login'),
-  GoRoute(
-    path: AppRoutes.register,
-    builder: (context, state) =>
-        const AuthRoutePlaceholder(routeKey: 'register'),
-    routes: [
-      GoRoute(
-        path: 'check-email',
-        builder: (context, state) =>
-            const AuthRoutePlaceholder(routeKey: 'check_email'),
-      ),
-    ],
-  ),
-  _placeholder(AppRoutes.forgotPassword, 'forgot_password'),
-  _placeholder(AppRoutes.authConfirm, 'auth_confirm'),
-  _placeholder(AppRoutes.resetPassword, 'reset_password'),
-];
-
-GoRoute _placeholder(String path, String key) => GoRoute(
+GoRoute authPlaceholderRoute(String path, String key) => GoRoute(
   path: path,
   builder: (context, state) => AuthRoutePlaceholder(routeKey: key),
 );

app/lib/features/auth/presentation/auth_routes.dart

@@ -0,0 +1,36 @@
+import 'package:go_router/go_router.dart';
+import 'package:shuffle/core/routing/app_routes.dart';
+import 'package:shuffle/features/auth/presentation/auth_route_placeholder.dart';
+import 'package:shuffle/features/auth/presentation/check_email/check_email_screen.dart';
+import 'package:shuffle/features/auth/presentation/email_link/email_link_screen.dart';
+import 'package:shuffle/features/auth/presentation/register/register_screen.dart';
+
+/// Routes of the auth pages (Spec #1 § 5.3). Login, forgot and reset password
+/// are placeholders until 01b and 01c.
+final List<RouteBase> authRoutes = [
+  authPlaceholderRoute(AppRoutes.login, 'login'),
+  GoRoute(
+    path: AppRoutes.register,
+    builder: (context, state) => const RegisterScreen(),
+    routes: [
+      GoRoute(
+        path: 'check-email',
+        builder: (context, state) {
+          // The address travels as `extra`, never in the URL. After a web
+          // reload it is gone; the screen then asks for it.
+          final extra = state.extra;
+          return CheckEmailScreen(email: extra is String ? extra : null);
+        },
+      ),
+    ],
+  ),
+  authPlaceholderRoute(AppRoutes.forgotPassword, 'forgot_password'),
+  GoRoute(
+    path: AppRoutes.authConfirm,
+    builder: (context, state) => EmailLinkScreen(
+      tokenHash: state.uri.queryParameters['token_hash'],
+      type: state.uri.queryParameters['type'],
+    ),
+  ),
+  authPlaceholderRoute(AppRoutes.resetPassword, 'reset_password'),
+];

app/lib/features/auth/presentation/check_email/check_email_screen.dart

@@ -0,0 +1,145 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:go_router/go_router.dart';
+import 'package:shuffle/core/config/auth_config.dart';
+import 'package:shuffle/core/l10n/l10n.dart';
+import 'package:shuffle/core/routing/app_routes.dart';
+import 'package:shuffle/core/theme/app_spacing.dart';
+import 'package:shuffle/core/widgets/app_banner.dart';
+import 'package:shuffle/core/widgets/app_form_scaffold.dart';
+import 'package:shuffle/core/widgets/app_primary_button.dart';
+import 'package:shuffle/core/widgets/app_text_field.dart';
+import 'package:shuffle/features/auth/domain/resend_origin.dart';
+import 'package:shuffle/features/auth/presentation/auth_failure_texts.dart';
+import 'package:shuffle/features/auth/presentation/check_email/resend_controller.dart';
+import 'package:shuffle/features/auth/presentation/widgets/auth_screen_title.dart';
+
+/// "Check your inbox" after the registration (`/register/check-email`,
+/// KTO-01 Kriterium 1, 4 und 6).
+///
+/// The text is neutral: it does not reveal whether the address already has an
+/// account (Kriterium 4). [email] comes from the router `extra`; after a web
+/// reload it is missing and the user types it in for "resend".
+class CheckEmailScreen extends ConsumerStatefulWidget {
+  const CheckEmailScreen({this.email, super.key});
+
+  final String? email;
+
+  @override
+  ConsumerState<CheckEmailScreen> createState() => _CheckEmailScreenState();
+}
+
+class _CheckEmailScreenState extends ConsumerState<CheckEmailScreen> {
+  final _emailController = TextEditingController();
+
+  bool get _hasKnownEmail => (widget.email ?? '').trim().isNotEmpty;
+
+  @override
+  void dispose() {
+    _emailController.dispose();
+    super.dispose();
+  }
+
+  void _resend() {
+    final email = _hasKnownEmail ? widget.email! : _emailController.text;
+    ref
+        .read(resendControllerProvider.notifier)
+        .resend(email, origin: ResendOrigin.checkEmail);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final state = ref.watch(resendControllerProvider);
+    final l10n = context.l10n;
+    final theme = Theme.of(context);
+    final failure = state.failure;
+
+    return AppFormScaffold(
+      key: const Key('check_email_screen'),
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.stretch,
+        children: [
+          AuthScreenTitle(l10n.authCheckEmailTitle),
+          const SizedBox(height: AppSpacing.lg),
+          Text(
+            l10n.authCheckEmailBody,
+            key: const Key('check_email_body'),
+            style: theme.textTheme.bodyLarge,
+          ),
+          const SizedBox(height: AppSpacing.sm),
+          Text(
+            l10n.authCheckEmailValidity(_validityText(l10n)),
+            key: const Key('check_email_validity'),
+            style: theme.textTheme.bodyMedium,
+          ),
+          const SizedBox(height: AppSpacing.sm),
+          Text(
+            l10n.authCheckEmailDelayHint,
+            key: const Key('check_email_delay_hint'),
+            style: theme.textTheme.bodyMedium,
+          ),
+          if (state.sent) ...[
+            const SizedBox(height: AppSpacing.lg),
+            AppBanner(
+              key: const Key('check_email_resent_banner'),
+              type: AppBannerType.info,
+              typeLabel: l10n.authBannerTypeInfo,
+              message: l10n.authCheckEmailResent,
+            ),
+          ],
+          if (failure != null) ...[
+            const SizedBox(height: AppSpacing.lg),
+            AppBanner(
+              key: const Key('check_email_error_banner'),
+              type: AppBannerType.error,
+              typeLabel: l10n.authBannerTypeError,
+              message: authFailureMessage(l10n, failure),
+            ),
+          ],
+          if (!_hasKnownEmail) ...[
+            const SizedBox(height: AppSpacing.xl),
+            AppTextField(
+              key: const Key('check_email_email'),
+              label: l10n.authFieldEmailLabel,
+              controller: _emailController,
+              keyboardType: TextInputType.emailAddress,
+              textInputAction: TextInputAction.done,
+              autofillHints: const [AutofillHints.email],
+              autocorrect: false,
+              enableSuggestions: false,
+              enabled: !state.isSending,
+              errorText: state.emailError == null
+                  ? null
+                  : l10n.authErrorEmailInvalid,
+              onChanged: (_) =>
+                  ref.read(resendControllerProvider.notifier).clearEmailError(),
+              onSubmitted: (_) => _resend(),
+            ),
+          ],
+          const SizedBox(height: AppSpacing.xl),
+          AppPrimaryButton(
+            key: const Key('check_email_resend'),
+            label: l10n.authCheckEmailResend,
+            loadingLabel: l10n.authSubmitting,
+            isLoading: state.isSending,
+            onPressed: _resend,
+          ),
+          const SizedBox(height: AppSpacing.sm),
+          TextButton(
+            key: const Key('check_email_back_to_login'),
+            onPressed: () => context.go(AppRoutes.login),
+            child: Text(l10n.authBackToLogin),
+          ),
+        ],
+      ),
+    );
+  }
+
+  String _validityText(AppLocalizations l10n) {
+    assert(
+      AuthConfig.linkValidity == const Duration(hours: 1),
+      'Update authCheckEmailValidityOneHour (AUTH-CFG-07 changed).',
+    );
+    return l10n.authCheckEmailValidityOneHour;
+  }
+}

app/lib/features/auth/presentation/check_email/resend_controller.dart

@@ -0,0 +1,66 @@
+import 'package:freezed_annotation/freezed_annotation.dart';
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+import 'package:shuffle/features/auth/domain/auth_failure.dart';
+import 'package:shuffle/features/auth/domain/resend_origin.dart';
+import 'package:shuffle/features/auth/domain/validation/email_format.dart';
+import 'package:shuffle/features/auth/presentation/providers/auth_providers.dart';
+
+part 'resend_controller.freezed.dart';
+part 'resend_controller.g.dart';
+
+@freezed
+abstract class ResendState with _$ResendState {
+  const factory ResendState({
+    @Default(false) bool isSending,
+
+    /// The last request counts as sent (also for `emailSendLimited` from the
+    /// check-email screen, F12).
+    @Default(false) bool sent,
+    AuthFailure? failure,
+
+    /// Only for an address typed in by the user.
+    EmailError? emailError,
+  }) = _ResendState;
+}
+
+/// "Resend email" for the confirmation (KTO-01 Kriterium 6, F12).
+///
+/// The caller states where the request comes from: only there the controller
+/// decides whether `emailSendLimited` is shown (login) or treated as success
+/// (check-email screen).
+@riverpod
+class ResendController extends _$ResendController {
+  @override
+  ResendState build() => const ResendState();
+
+  void clearEmailError() {
+    if (state.emailError != null) {
+      state = state.copyWith(emailError: null);
+    }
+  }
+
+  Future<void> resend(String email, {required ResendOrigin origin}) async {
+    if (state.isSending) {
+      return;
+    }
+    final normalized = EmailFormat.normalize(email);
+    final emailError = EmailFormat.validate(normalized);
+    if (emailError != null) {
+      state = ResendState(emailError: emailError);
+      return;
+    }
+
+    state = const ResendState(isSending: true);
+    final result = await ref
+        .read(authRepositoryProvider)
+        .resendConfirmation(normalized);
+    if (!ref.mounted) {
+      return;
+    }
+    final raw = result.errorOrNull;
+    final failure = raw == null ? null : resendFailureFor(raw, origin);
+    state = failure == null
+        ? const ResendState(sent: true)
+        : ResendState(failure: failure);
+  }
+}

app/lib/features/auth/presentation/check_email/resend_controller.freezed.dart

@@ -0,0 +1,318 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+// coverage:ignore-file
+// ignore_for_file: type=lint, type=warning, deprecated_member_use, deprecated_member_use_from_same_package
+// ignore_for_file: unused_element, deprecated_member_use, deprecated_member_use_from_same_package, use_function_type_syntax_for_parameters, unnecessary_const, avoid_init_to_null, invalid_override_different_default_values_named, prefer_expression_function_bodies, annotate_overrides, invalid_annotation_target, unnecessary_question_mark
+
+part of 'resend_controller.dart';
+
+// **************************************************************************
+// FreezedGenerator
+// **************************************************************************
+
+// GENERATED CODE - DO NOT MODIFY BY HAND
+// dart format off
+T _$identity<T>(T value) => value;
+/// @nodoc
+mixin _$ResendState {
+
+ bool get isSending;/// The last request counts as sent (also for `emailSendLimited` from the
+/// check-email screen, F12).
+ bool get sent; AuthFailure? get failure;/// Only for an address typed in by the user.
+ EmailError? get emailError;
+/// Create a copy of ResendState
+/// with the given fields replaced by the non-null parameter values.
+@JsonKey(includeFromJson: false, includeToJson: false)
+@pragma('vm:prefer-inline')
+$ResendStateCopyWith<ResendState> get copyWith => _$ResendStateCopyWithImpl<ResendState>(this as ResendState, _$identity);
+
+
+
+@override
+bool operator ==(Object other) {
+  final _this = this as ResendState;
+  return identical(this, other) || (other.runtimeType == runtimeType&&other is ResendState&&(identical(other.isSending, _this.isSending) || other.isSending == _this.isSending)&&(identical(other.sent, _this.sent) || other.sent == _this.sent)&&(identical(other.failure, _this.failure) || other.failure == _this.failure)&&(identical(other.emailError, _this.emailError) || other.emailError == _this.emailError));
+}
+
+
+@override
+int get hashCode {
+  final _this = this as ResendState;
+  return Object.hash(runtimeType,_this.isSending,_this.sent,_this.failure,_this.emailError);
+}
+
+@override
+String toString() {
+  final _this = this as ResendState;
+  return 'ResendState(isSending: ${_this.isSending}, sent: ${_this.sent}, failure: ${_this.failure}, emailError: ${_this.emailError})';
+}
+
+
+}
+
+/// @nodoc
+abstract mixin class $ResendStateCopyWith<$Res>  {
+  factory $ResendStateCopyWith(ResendState value, $Res Function(ResendState) _then) = _$ResendStateCopyWithImpl;
+@useResult
+$Res call({
+ bool isSending, bool sent, AuthFailure? failure, EmailError? emailError
+});
+
+
+$AuthFailureCopyWith<$Res>? get failure;
+
+}
+/// @nodoc
+class _$ResendStateCopyWithImpl<$Res>
+    implements $ResendStateCopyWith<$Res> {
+  _$ResendStateCopyWithImpl(this._self, this._then);
+
+  final ResendState _self;
+  final $Res Function(ResendState) _then;
+
+/// Create a copy of ResendState
+/// with the given fields replaced by the non-null parameter values.
+@pragma('vm:prefer-inline') @override $Res call({Object? isSending = null,Object? sent = null,Object? failure = freezed,Object? emailError = freezed,}) {
+  return _then(ResendState(
+isSending: null == isSending ? _self.isSending : isSending // ignore: cast_nullable_to_non_nullable
+as bool,sent: null == sent ? _self.sent : sent // ignore: cast_nullable_to_non_nullable
+as bool,failure: freezed == failure ? _self.failure : failure // ignore: cast_nullable_to_non_nullable
+as AuthFailure?,emailError: freezed == emailError ? _self.emailError : emailError // ignore: cast_nullable_to_non_nullable
+as EmailError?,
+  ));
+}
+/// Create a copy of ResendState
+/// with the given fields replaced by the non-null parameter values.
+@override
+@pragma('vm:prefer-inline')
+$AuthFailureCopyWith<$Res>? get failure {
+    if (_self.failure == null) {
+    return null;
+  }
+
+  return $AuthFailureCopyWith<$Res>(_self.failure!, (value) {
+    return _then(_self.copyWith(failure: value));
+  });
+}
+}
+
+
+/// Adds pattern-matching-related methods to [ResendState].
+extension ResendStatePatterns on ResendState {
+/// A variant of `map` that fallback to returning `orElse`.
+///
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case final Subclass value:
+///     return ...;
+///   case _:
+///     return orElse();
+/// }
+/// ```
+
+@optionalTypeArgs TResult maybeMap<TResult extends Object?>(TResult Function( _ResendState value)?  $default,{required TResult orElse(),}){
+final _that = this;
+switch (_that) {
+case _ResendState() when $default != null:
+return $default(_that);case _:
+  return orElse();
+
+}
+}
+/// A `switch`-like method, using callbacks.
+///
+/// Callbacks receives the raw object, upcasted.
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case final Subclass value:
+///     return ...;
+///   case final Subclass2 value:
+///     return ...;
+/// }
+/// ```
+
+@optionalTypeArgs TResult map<TResult extends Object?>(TResult Function( _ResendState value)  $default,){
+final _that = this;
+switch (_that) {
+case _ResendState():
+return $default(_that);case _:
+  throw StateError('Unexpected subclass');
+
+}
+}
+/// A variant of `map` that fallback to returning `null`.
+///
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case final Subclass value:
+///     return ...;
+///   case _:
+///     return null;
+/// }
+/// ```
+
+@optionalTypeArgs TResult? mapOrNull<TResult extends Object?>(TResult? Function( _ResendState value)?  $default,){
+final _that = this;
+switch (_that) {
+case _ResendState() when $default != null:
+return $default(_that);case _:
+  return null;
+
+}
+}
+/// A variant of `when` that fallback to an `orElse` callback.
+///
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case Subclass(:final field):
+///     return ...;
+///   case _:
+///     return orElse();
+/// }
+/// ```
+
+@optionalTypeArgs TResult maybeWhen<TResult extends Object?>(TResult Function( bool isSending,  bool sent,  AuthFailure? failure,  EmailError? emailError)?  $default,{required TResult orElse(),}) {final _that = this;
+switch (_that) {
+case _ResendState() when $default != null:
+return $default(_that.isSending,_that.sent,_that.failure,_that.emailError);case _:
+  return orElse();
+
+}
+}
+/// A `switch`-like method, using callbacks.
+///
+/// As opposed to `map`, this offers destructuring.
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case Subclass(:final field):
+///     return ...;
+///   case Subclass2(:final field2):
+///     return ...;
+/// }
+/// ```
+
+@optionalTypeArgs TResult when<TResult extends Object?>(TResult Function( bool isSending,  bool sent,  AuthFailure? failure,  EmailError? emailError)  $default,) {final _that = this;
+switch (_that) {
+case _ResendState():
+return $default(_that.isSending,_that.sent,_that.failure,_that.emailError);case _:
+  throw StateError('Unexpected subclass');
+
+}
+}
+/// A variant of `when` that fallback to returning `null`
+///
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case Subclass(:final field):
+///     return ...;
+///   case _:
+///     return null;
+/// }
+/// ```
+
+@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>(TResult? Function( bool isSending,  bool sent,  AuthFailure? failure,  EmailError? emailError)?  $default,) {final _that = this;
+switch (_that) {
+case _ResendState() when $default != null:
+return $default(_that.isSending,_that.sent,_that.failure,_that.emailError);case _:
+  return null;
+
+}
+}
+
+}
+
+/// @nodoc
+
+
+class _ResendState implements ResendState {
+  const _ResendState({this.isSending = false, this.sent = false, this.failure, this.emailError});
+  
+
+@override@JsonKey() final  bool isSending;
+/// The last request counts as sent (also for `emailSendLimited` from the
+/// check-email screen, F12).
+@override@JsonKey() final  bool sent;
+@override final  AuthFailure? failure;
+/// Only for an address typed in by the user.
+@override final  EmailError? emailError;
+
+/// Create a copy of ResendState
+/// with the given fields replaced by the non-null parameter values.
+@override @JsonKey(includeFromJson: false, includeToJson: false)
+@pragma('vm:prefer-inline')
+_$ResendStateCopyWith<_ResendState> get copyWith => __$ResendStateCopyWithImpl<_ResendState>(this, _$identity);
+
+
+
+@override
+bool operator ==(Object other) {
+    return identical(this, other) || (other.runtimeType == runtimeType&&other is _ResendState&&(identical(other.isSending, isSending) || other.isSending == isSending)&&(identical(other.sent, sent) || other.sent == sent)&&(identical(other.failure, failure) || other.failure == failure)&&(identical(other.emailError, emailError) || other.emailError == emailError));
+}
+
+
+@override
+int get hashCode {
+    return Object.hash(runtimeType,isSending,sent,failure,emailError);
+}
+
+@override
+String toString() {
+    return 'ResendState(isSending: $isSending, sent: $sent, failure: $failure, emailError: $emailError)';
+}
+
+
+}
+
+/// @nodoc
+abstract mixin class _$ResendStateCopyWith<$Res> implements $ResendStateCopyWith<$Res> {
+  factory _$ResendStateCopyWith(_ResendState value, $Res Function(_ResendState) _then) = __$ResendStateCopyWithImpl;
+@override @useResult
+$Res call({
+ bool isSending, bool sent, AuthFailure? failure, EmailError? emailError
+});
+
+
+@override $AuthFailureCopyWith<$Res>? get failure;
+
+}
+/// @nodoc
+class __$ResendStateCopyWithImpl<$Res>
+    implements _$ResendStateCopyWith<$Res> {
+  __$ResendStateCopyWithImpl(this._self, this._then);
+
+  final _ResendState _self;
+  final $Res Function(_ResendState) _then;
+
+/// Create a copy of ResendState
+/// with the given fields replaced by the non-null parameter values.
+@override @pragma('vm:prefer-inline') $Res call({Object? isSending = null,Object? sent = null,Object? failure = freezed,Object? emailError = freezed,}) {
+  return _then(_ResendState(
+isSending: null == isSending ? _self.isSending : isSending // ignore: cast_nullable_to_non_nullable
+as bool,sent: null == sent ? _self.sent : sent // ignore: cast_nullable_to_non_nullable
+as bool,failure: freezed == failure ? _self.failure : failure // ignore: cast_nullable_to_non_nullable
+as AuthFailure?,emailError: freezed == emailError ? _self.emailError : emailError // ignore: cast_nullable_to_non_nullable
+as EmailError?,
+  ));
+}
+
+/// Create a copy of ResendState
+/// with the given fields replaced by the non-null parameter values.
+@override
+@pragma('vm:prefer-inline')
+$AuthFailureCopyWith<$Res>? get failure {
+    if (_self.failure == null) {
+    return null;
+  }
+
+  return $AuthFailureCopyWith<$Res>(_self.failure!, (value) {
+    return _then(_self.copyWith(failure: value));
+  });
+}
+}
+
+// dart format on

app/lib/features/auth/presentation/check_email/resend_controller.g.dart

@@ -0,0 +1,83 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'resend_controller.dart';
+
+// **************************************************************************
+// RiverpodGenerator
+// **************************************************************************
+
+// GENERATED CODE - DO NOT MODIFY BY HAND
+// ignore_for_file: type=lint, type=warning
+/// "Resend email" for the confirmation (KTO-01 Kriterium 6, F12).
+///
+/// The caller states where the request comes from: only there the controller
+/// decides whether `emailSendLimited` is shown (login) or treated as success
+/// (check-email screen).
+
+@ProviderFor(ResendController)
+final resendControllerProvider = ResendControllerProvider._();
+
+/// "Resend email" for the confirmation (KTO-01 Kriterium 6, F12).
+///
+/// The caller states where the request comes from: only there the controller
+/// decides whether `emailSendLimited` is shown (login) or treated as success
+/// (check-email screen).
+final class ResendControllerProvider
+    extends $NotifierProvider<ResendController, ResendState> {
+  /// "Resend email" for the confirmation (KTO-01 Kriterium 6, F12).
+  ///
+  /// The caller states where the request comes from: only there the controller
+  /// decides whether `emailSendLimited` is shown (login) or treated as success
+  /// (check-email screen).
+  ResendControllerProvider._()
+    : super(
+        from: null,
+        argument: null,
+        retry: null,
+        name: r'resendControllerProvider',
+        isAutoDispose: true,
+        dependencies: null,
+        $allTransitiveDependencies: null,
+      );
+
+  @override
+  String debugGetCreateSourceHash() => _$resendControllerHash();
+
+  @$internal
+  @override
+  ResendController create() => ResendController();
+
+  /// {@macro riverpod.override_with_value}
+  Override overrideWithValue(ResendState value) {
+    return $ProviderOverride(
+      origin: this,
+      providerOverride: $SyncValueProvider<ResendState>(value),
+    );
+  }
+}
+
+String _$resendControllerHash() => r'cab54661555bb641d3dc0fb1b06486b10f2e59e8';
+
+/// "Resend email" for the confirmation (KTO-01 Kriterium 6, F12).
+///
+/// The caller states where the request comes from: only there the controller
+/// decides whether `emailSendLimited` is shown (login) or treated as success
+/// (check-email screen).
+
+abstract class _$ResendController extends $Notifier<ResendState> {
+  ResendState build();
+  @$mustCallSuper
+  @override
+  WhenComplete runBuild() {
+    final ref = this.ref as $Ref<ResendState, ResendState>;
+    final element =
+        ref.element
+            as $ClassProviderElement<
+              AnyNotifier<ResendState, ResendState>,
+              ResendState,
+              Object?,
+              Object?
+            >;
+    return element.handleCreate(ref, build);
+  }
+}

app/lib/features/auth/presentation/email_link/email_link_controller.dart

@@ -0,0 +1,63 @@
+import 'package:freezed_annotation/freezed_annotation.dart';
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+import 'package:shuffle/features/auth/domain/auth_failure.dart';
+import 'package:shuffle/features/auth/domain/email_link_request.dart';
+import 'package:shuffle/features/auth/presentation/providers/auth_providers.dart';
+
+part 'email_link_controller.freezed.dart';
+part 'email_link_controller.g.dart';
+
+enum EmailLinkPhase {
+  /// Waiting for the click.
+  ready,
+  submitting,
+  success,
+
+  /// Link missing, invalid, expired or used.
+  invalid,
+}
+
+@freezed
+abstract class EmailLinkState with _$EmailLinkState {
+  const factory EmailLinkState({
+    required EmailLinkPhase phase,
+    EmailLinkRequest? request,
+
+    /// Failure that allows another try (network, rate limit, unexpected).
+    AuthFailure? failure,
+  }) = _EmailLinkState;
+}
+
+/// Redeems a mail link (KTO-01 Kriterium 1, 8). The link is redeemed only
+/// by [confirm] (a button press), never when the screen opens, so mail
+/// scanners cannot use up the one-time token (Spec #1, E3).
+@riverpod
+class EmailLinkController extends _$EmailLinkController {
+  @override
+  EmailLinkState build(String? tokenHash, String? type) {
+    final request = EmailLinkRequest.tryParse(tokenHash, type);
+    return request == null
+        ? const EmailLinkState(phase: EmailLinkPhase.invalid)
+        : EmailLinkState(phase: EmailLinkPhase.ready, request: request);
+  }
+
+  Future<void> confirm() async {
+    final request = state.request;
+    if (request == null || state.phase != EmailLinkPhase.ready) {
+      return;
+    }
+    state = state.copyWith(phase: EmailLinkPhase.submitting, failure: null);
+    final result = await ref
+        .read(authRepositoryProvider)
+        .verifyEmailLink(request.tokenHash, request.type);
+    if (!ref.mounted) {
+      return;
+    }
+    final failure = result.errorOrNull;
+    state = switch (failure) {
+      null => state.copyWith(phase: EmailLinkPhase.success),
+      LinkInvalidOrExpired() => state.copyWith(phase: EmailLinkPhase.invalid),
+      _ => state.copyWith(phase: EmailLinkPhase.ready, failure: failure),
+    };
+  }
+}

app/lib/features/auth/presentation/email_link/email_link_controller.freezed.dart

@@ -0,0 +1,311 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+// coverage:ignore-file
+// ignore_for_file: type=lint, type=warning, deprecated_member_use, deprecated_member_use_from_same_package
+// ignore_for_file: unused_element, deprecated_member_use, deprecated_member_use_from_same_package, use_function_type_syntax_for_parameters, unnecessary_const, avoid_init_to_null, invalid_override_different_default_values_named, prefer_expression_function_bodies, annotate_overrides, invalid_annotation_target, unnecessary_question_mark
+
+part of 'email_link_controller.dart';
+
+// **************************************************************************
+// FreezedGenerator
+// **************************************************************************
+
+// GENERATED CODE - DO NOT MODIFY BY HAND
+// dart format off
+T _$identity<T>(T value) => value;
+/// @nodoc
+mixin _$EmailLinkState {
+
+ EmailLinkPhase get phase; EmailLinkRequest? get request;/// Failure that allows another try (network, rate limit, unexpected).
+ AuthFailure? get failure;
+/// Create a copy of EmailLinkState
+/// with the given fields replaced by the non-null parameter values.
+@JsonKey(includeFromJson: false, includeToJson: false)
+@pragma('vm:prefer-inline')
+$EmailLinkStateCopyWith<EmailLinkState> get copyWith => _$EmailLinkStateCopyWithImpl<EmailLinkState>(this as EmailLinkState, _$identity);
+
+
+
+@override
+bool operator ==(Object other) {
+  final _this = this as EmailLinkState;
+  return identical(this, other) || (other.runtimeType == runtimeType&&other is EmailLinkState&&(identical(other.phase, _this.phase) || other.phase == _this.phase)&&(identical(other.request, _this.request) || other.request == _this.request)&&(identical(other.failure, _this.failure) || other.failure == _this.failure));
+}
+
+
+@override
+int get hashCode {
+  final _this = this as EmailLinkState;
+  return Object.hash(runtimeType,_this.phase,_this.request,_this.failure);
+}
+
+@override
+String toString() {
+  final _this = this as EmailLinkState;
+  return 'EmailLinkState(phase: ${_this.phase}, request: ${_this.request}, failure: ${_this.failure})';
+}
+
+
+}
+
+/// @nodoc
+abstract mixin class $EmailLinkStateCopyWith<$Res>  {
+  factory $EmailLinkStateCopyWith(EmailLinkState value, $Res Function(EmailLinkState) _then) = _$EmailLinkStateCopyWithImpl;
+@useResult
+$Res call({
+ EmailLinkPhase phase, EmailLinkRequest? request, AuthFailure? failure
+});
+
+
+$AuthFailureCopyWith<$Res>? get failure;
+
+}
+/// @nodoc
+class _$EmailLinkStateCopyWithImpl<$Res>
+    implements $EmailLinkStateCopyWith<$Res> {
+  _$EmailLinkStateCopyWithImpl(this._self, this._then);
+
+  final EmailLinkState _self;
+  final $Res Function(EmailLinkState) _then;
+
+/// Create a copy of EmailLinkState
+/// with the given fields replaced by the non-null parameter values.
+@pragma('vm:prefer-inline') @override $Res call({Object? phase = null,Object? request = freezed,Object? failure = freezed,}) {
+  return _then(EmailLinkState(
+phase: null == phase ? _self.phase : phase // ignore: cast_nullable_to_non_nullable
+as EmailLinkPhase,request: freezed == request ? _self.request : request // ignore: cast_nullable_to_non_nullable
+as EmailLinkRequest?,failure: freezed == failure ? _self.failure : failure // ignore: cast_nullable_to_non_nullable
+as AuthFailure?,
+  ));
+}
+/// Create a copy of EmailLinkState
+/// with the given fields replaced by the non-null parameter values.
+@override
+@pragma('vm:prefer-inline')
+$AuthFailureCopyWith<$Res>? get failure {
+    if (_self.failure == null) {
+    return null;
+  }
+
+  return $AuthFailureCopyWith<$Res>(_self.failure!, (value) {
+    return _then(_self.copyWith(failure: value));
+  });
+}
+}
+
+
+/// Adds pattern-matching-related methods to [EmailLinkState].
+extension EmailLinkStatePatterns on EmailLinkState {
+/// A variant of `map` that fallback to returning `orElse`.
+///
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case final Subclass value:
+///     return ...;
+///   case _:
+///     return orElse();
+/// }
+/// ```
+
+@optionalTypeArgs TResult maybeMap<TResult extends Object?>(TResult Function( _EmailLinkState value)?  $default,{required TResult orElse(),}){
+final _that = this;
+switch (_that) {
+case _EmailLinkState() when $default != null:
+return $default(_that);case _:
+  return orElse();
+
+}
+}
+/// A `switch`-like method, using callbacks.
+///
+/// Callbacks receives the raw object, upcasted.
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case final Subclass value:
+///     return ...;
+///   case final Subclass2 value:
+///     return ...;
+/// }
+/// ```
+
+@optionalTypeArgs TResult map<TResult extends Object?>(TResult Function( _EmailLinkState value)  $default,){
+final _that = this;
+switch (_that) {
+case _EmailLinkState():
+return $default(_that);case _:
+  throw StateError('Unexpected subclass');
+
+}
+}
+/// A variant of `map` that fallback to returning `null`.
+///
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case final Subclass value:
+///     return ...;
+///   case _:
+///     return null;
+/// }
+/// ```
+
+@optionalTypeArgs TResult? mapOrNull<TResult extends Object?>(TResult? Function( _EmailLinkState value)?  $default,){
+final _that = this;
+switch (_that) {
+case _EmailLinkState() when $default != null:
+return $default(_that);case _:
+  return null;
+
+}
+}
+/// A variant of `when` that fallback to an `orElse` callback.
+///
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case Subclass(:final field):
+///     return ...;
+///   case _:
+///     return orElse();
+/// }
+/// ```
+
+@optionalTypeArgs TResult maybeWhen<TResult extends Object?>(TResult Function( EmailLinkPhase phase,  EmailLinkRequest? request,  AuthFailure? failure)?  $default,{required TResult orElse(),}) {final _that = this;
+switch (_that) {
+case _EmailLinkState() when $default != null:
+return $default(_that.phase,_that.request,_that.failure);case _:
+  return orElse();
+
+}
+}
+/// A `switch`-like method, using callbacks.
+///
+/// As opposed to `map`, this offers destructuring.
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case Subclass(:final field):
+///     return ...;
+///   case Subclass2(:final field2):
+///     return ...;
+/// }
+/// ```
+
+@optionalTypeArgs TResult when<TResult extends Object?>(TResult Function( EmailLinkPhase phase,  EmailLinkRequest? request,  AuthFailure? failure)  $default,) {final _that = this;
+switch (_that) {
+case _EmailLinkState():
+return $default(_that.phase,_that.request,_that.failure);case _:
+  throw StateError('Unexpected subclass');
+
+}
+}
+/// A variant of `when` that fallback to returning `null`
+///
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case Subclass(:final field):
+///     return ...;
+///   case _:
+///     return null;
+/// }
+/// ```
+
+@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>(TResult? Function( EmailLinkPhase phase,  EmailLinkRequest? request,  AuthFailure? failure)?  $default,) {final _that = this;
+switch (_that) {
+case _EmailLinkState() when $default != null:
+return $default(_that.phase,_that.request,_that.failure);case _:
+  return null;
+
+}
+}
+
+}
+
+/// @nodoc
+
+
+class _EmailLinkState implements EmailLinkState {
+  const _EmailLinkState({required this.phase, this.request, this.failure});
+  
+
+@override final  EmailLinkPhase phase;
+@override final  EmailLinkRequest? request;
+/// Failure that allows another try (network, rate limit, unexpected).
+@override final  AuthFailure? failure;
+
+/// Create a copy of EmailLinkState
+/// with the given fields replaced by the non-null parameter values.
+@override @JsonKey(includeFromJson: false, includeToJson: false)
+@pragma('vm:prefer-inline')
+_$EmailLinkStateCopyWith<_EmailLinkState> get copyWith => __$EmailLinkStateCopyWithImpl<_EmailLinkState>(this, _$identity);
+
+
+
+@override
+bool operator ==(Object other) {
+    return identical(this, other) || (other.runtimeType == runtimeType&&other is _EmailLinkState&&(identical(other.phase, phase) || other.phase == phase)&&(identical(other.request, request) || other.request == request)&&(identical(other.failure, failure) || other.failure == failure));
+}
+
+
+@override
+int get hashCode {
+    return Object.hash(runtimeType,phase,request,failure);
+}
+
+@override
+String toString() {
+    return 'EmailLinkState(phase: $phase, request: $request, failure: $failure)';
+}
+
+
+}
+
+/// @nodoc
+abstract mixin class _$EmailLinkStateCopyWith<$Res> implements $EmailLinkStateCopyWith<$Res> {
+  factory _$EmailLinkStateCopyWith(_EmailLinkState value, $Res Function(_EmailLinkState) _then) = __$EmailLinkStateCopyWithImpl;
+@override @useResult
+$Res call({
+ EmailLinkPhase phase, EmailLinkRequest? request, AuthFailure? failure
+});
+
+
+@override $AuthFailureCopyWith<$Res>? get failure;
+
+}
+/// @nodoc
+class __$EmailLinkStateCopyWithImpl<$Res>
+    implements _$EmailLinkStateCopyWith<$Res> {
+  __$EmailLinkStateCopyWithImpl(this._self, this._then);
+
+  final _EmailLinkState _self;
+  final $Res Function(_EmailLinkState) _then;
+
+/// Create a copy of EmailLinkState
+/// with the given fields replaced by the non-null parameter values.
+@override @pragma('vm:prefer-inline') $Res call({Object? phase = null,Object? request = freezed,Object? failure = freezed,}) {
+  return _then(_EmailLinkState(
+phase: null == phase ? _self.phase : phase // ignore: cast_nullable_to_non_nullable
+as EmailLinkPhase,request: freezed == request ? _self.request : request // ignore: cast_nullable_to_non_nullable
+as EmailLinkRequest?,failure: freezed == failure ? _self.failure : failure // ignore: cast_nullable_to_non_nullable
+as AuthFailure?,
+  ));
+}
+
+/// Create a copy of EmailLinkState
+/// with the given fields replaced by the non-null parameter values.
+@override
+@pragma('vm:prefer-inline')
+$AuthFailureCopyWith<$Res>? get failure {
+    if (_self.failure == null) {
+    return null;
+  }
+
+  return $AuthFailureCopyWith<$Res>(_self.failure!, (value) {
+    return _then(_self.copyWith(failure: value));
+  });
+}
+}
+
+// dart format on

app/lib/features/auth/presentation/email_link/email_link_controller.g.dart

@@ -0,0 +1,130 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'email_link_controller.dart';
+
+// **************************************************************************
+// RiverpodGenerator
+// **************************************************************************
+
+// GENERATED CODE - DO NOT MODIFY BY HAND
+// ignore_for_file: type=lint, type=warning
+/// Redeems a mail link (KTO-01 Kriterium 1, 8). The link is redeemed only
+/// by [confirm] (a button press), never when the screen opens, so mail
+/// scanners cannot use up the one-time token (Spec #1, E3).
+
+@ProviderFor(EmailLinkController)
+final emailLinkControllerProvider = EmailLinkControllerFamily._();
+
+/// Redeems a mail link (KTO-01 Kriterium 1, 8). The link is redeemed only
+/// by [confirm] (a button press), never when the screen opens, so mail
+/// scanners cannot use up the one-time token (Spec #1, E3).
+final class EmailLinkControllerProvider
+    extends $NotifierProvider<EmailLinkController, EmailLinkState> {
+  /// Redeems a mail link (KTO-01 Kriterium 1, 8). The link is redeemed only
+  /// by [confirm] (a button press), never when the screen opens, so mail
+  /// scanners cannot use up the one-time token (Spec #1, E3).
+  EmailLinkControllerProvider._({
+    required EmailLinkControllerFamily super.from,
+    required (String?, String?) super.argument,
+  }) : super(
+         retry: null,
+         name: r'emailLinkControllerProvider',
+         isAutoDispose: true,
+         dependencies: null,
+         $allTransitiveDependencies: null,
+       );
+
+  @override
+  String debugGetCreateSourceHash() => _$emailLinkControllerHash();
+
+  @override
+  String toString() {
+    return r'emailLinkControllerProvider'
+        ''
+        '$argument';
+  }
+
+  @$internal
+  @override
+  EmailLinkController create() => EmailLinkController();
+
+  /// {@macro riverpod.override_with_value}
+  Override overrideWithValue(EmailLinkState value) {
+    return $ProviderOverride(
+      origin: this,
+      providerOverride: $SyncValueProvider<EmailLinkState>(value),
+    );
+  }
+
+  @override
+  bool operator ==(Object other) {
+    return other is EmailLinkControllerProvider && other.argument == argument;
+  }
+
+  @override
+  int get hashCode {
+    return argument.hashCode;
+  }
+}
+
+String _$emailLinkControllerHash() =>
+    r'90d3746ab8aa2ceb60122ee09c942cac6dd49249';
+
+/// Redeems a mail link (KTO-01 Kriterium 1, 8). The link is redeemed only
+/// by [confirm] (a button press), never when the screen opens, so mail
+/// scanners cannot use up the one-time token (Spec #1, E3).
+
+final class EmailLinkControllerFamily extends $Family
+    with
+        $ClassFamilyOverride<
+          EmailLinkController,
+          EmailLinkState,
+          EmailLinkState,
+          EmailLinkState,
+          (String?, String?)
+        > {
+  EmailLinkControllerFamily._()
+    : super(
+        retry: null,
+        name: r'emailLinkControllerProvider',
+        dependencies: null,
+        $allTransitiveDependencies: null,
+        isAutoDispose: true,
+      );
+
+  /// Redeems a mail link (KTO-01 Kriterium 1, 8). The link is redeemed only
+  /// by [confirm] (a button press), never when the screen opens, so mail
+  /// scanners cannot use up the one-time token (Spec #1, E3).
+
+  EmailLinkControllerProvider call(String? tokenHash, String? type) =>
+      EmailLinkControllerProvider._(argument: (tokenHash, type), from: this);
+
+  @override
+  String toString() => r'emailLinkControllerProvider';
+}
+
+/// Redeems a mail link (KTO-01 Kriterium 1, 8). The link is redeemed only
+/// by [confirm] (a button press), never when the screen opens, so mail
+/// scanners cannot use up the one-time token (Spec #1, E3).
+
+abstract class _$EmailLinkController extends $Notifier<EmailLinkState> {
+  late final _$args = ref.$arg as (String?, String?);
+  String? get tokenHash => _$args.$1;
+  String? get type => _$args.$2;
+
+  EmailLinkState build(String? tokenHash, String? type);
+  @$mustCallSuper
+  @override
+  WhenComplete runBuild() {
+    final ref = this.ref as $Ref<EmailLinkState, EmailLinkState>;
+    final element =
+        ref.element
+            as $ClassProviderElement<
+              AnyNotifier<EmailLinkState, EmailLinkState>,
+              EmailLinkState,
+              Object?,
+              Object?
+            >;
+    return element.handleCreate(ref, () => build(_$args.$1, _$args.$2));
+  }
+}

app/lib/features/auth/presentation/email_link/email_link_screen.dart

@@ -0,0 +1,135 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:go_router/go_router.dart';
+import 'package:shuffle/core/l10n/l10n.dart';
+import 'package:shuffle/core/platform/platform_info.dart';
+import 'package:shuffle/core/routing/app_routes.dart';
+import 'package:shuffle/core/theme/app_spacing.dart';
+import 'package:shuffle/core/widgets/app_banner.dart';
+import 'package:shuffle/core/widgets/app_form_scaffold.dart';
+import 'package:shuffle/core/widgets/app_primary_button.dart';
+import 'package:shuffle/features/auth/domain/email_link_type.dart';
+import 'package:shuffle/features/auth/presentation/auth_failure_texts.dart';
+import 'package:shuffle/features/auth/presentation/email_link/email_link_controller.dart';
+import 'package:shuffle/features/auth/presentation/widgets/auth_screen_title.dart';
+
+/// Landing page of the mail links (`/auth/confirm?token_hash=…&type=…`,
+/// KTO-01 Kriterium 1 und 8).
+///
+/// Redeeming needs a button press (Spec #1, E3): mail scanners that only open
+/// the URL must not use up the one-time token.
+class EmailLinkScreen extends ConsumerWidget {
+  const EmailLinkScreen({this.tokenHash, this.type, super.key});
+
+  final String? tokenHash;
+  final String? type;
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final provider = emailLinkControllerProvider(tokenHash, type);
+    final state = ref.watch(provider);
+    final controller = ref.read(provider.notifier);
+    final l10n = context.l10n;
+    final theme = Theme.of(context);
+    final linkType = state.request?.type ?? EmailLinkType.tryParse(type);
+    final isRecovery = linkType == EmailLinkType.recovery;
+    final title = isRecovery ? l10n.authRecoveryTitle : l10n.authConfirmTitle;
+
+    final Widget content;
+    switch (state.phase) {
+      case EmailLinkPhase.invalid:
+        content = AppBanner(
+          key: const Key('email_link_invalid_banner'),
+          type: AppBannerType.error,
+          typeLabel: l10n.authBannerTypeError,
+          message: l10n.authErrorLinkInvalidOrExpired,
+          actionLabel: l10n.authActionRequestNewLink,
+          onAction: () => context.go(
+            isRecovery ? AppRoutes.forgotPassword : AppRoutes.login,
+          ),
+        );
+      case EmailLinkPhase.success:
+        content = _Success(isRecovery: isRecovery);
+      case EmailLinkPhase.ready || EmailLinkPhase.submitting:
+        final failure = state.failure;
+        content = Column(
+          crossAxisAlignment: CrossAxisAlignment.stretch,
+          children: [
+            if (failure != null) ...[
+              AppBanner(
+                key: const Key('email_link_error_banner'),
+                type: AppBannerType.error,
+                typeLabel: l10n.authBannerTypeError,
+                message: authFailureMessage(l10n, failure),
+              ),
+              const SizedBox(height: AppSpacing.lg),
+            ],
+            Text(
+              isRecovery ? l10n.authRecoveryBody : l10n.authConfirmBody,
+              key: const Key('email_link_body'),
+              style: theme.textTheme.bodyLarge,
+            ),
+            const SizedBox(height: AppSpacing.xl),
+            AppPrimaryButton(
+              key: const Key('email_link_submit'),
+              label: isRecovery
+                  ? l10n.authRecoverySubmit
+                  : l10n.authConfirmSubmit,
+              loadingLabel: l10n.authSubmitting,
+              isLoading: state.phase == EmailLinkPhase.submitting,
+              onPressed: controller.confirm,
+            ),
+          ],
+        );
+    }
+
+    return AppFormScaffold(
+      key: const Key('email_link_screen'),
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.stretch,
+        children: [
+          AuthScreenTitle(title),
+          const SizedBox(height: AppSpacing.lg),
+          content,
+        ],
+      ),
+    );
+  }
+}
+
+class _Success extends ConsumerWidget {
+  const _Success({required this.isRecovery});
+
+  final bool isRecovery;
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final l10n = context.l10n;
+    final mobileWeb = ref.watch(isMobileWebProvider);
+    // Recovery continues automatically: the status change sends the user to
+    // the "new password" page (router redirect).
+    if (isRecovery) {
+      return const SizedBox.shrink();
+    }
+    final message = mobileWeb
+        ? '${l10n.authConfirmSuccess} ${l10n.authConfirmSuccessMobileWeb}'
+        : l10n.authConfirmSuccess;
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.stretch,
+      children: [
+        AppBanner(
+          key: const Key('email_link_success_banner'),
+          type: AppBannerType.info,
+          typeLabel: l10n.authBannerTypeInfo,
+          message: message,
+        ),
+        const SizedBox(height: AppSpacing.xl),
+        AppPrimaryButton(
+          key: const Key('email_link_continue'),
+          label: l10n.authConfirmContinue,
+          onPressed: () => context.go(AppRoutes.home),
+        ),
+      ],
+    );
+  }
+}

app/lib/features/auth/presentation/providers/auth_providers.dart

@@ -25,9 +25,13 @@ AuthRepository authRepository(Ref ref) {
 Stream<AuthStatus> authStatus(Ref ref) =>
     ref.watch(authRepositoryProvider).watchStatus();
 
+Duration? _noRetry(int retryCount, Object error) => null;
+
 /// Liste häufiger Passwörter. Lazy: lädt erst beim ersten Lesen (Öffnen eines
-/// Passwortfeldes), nicht beim App-Start.
-@Riverpod(keepAlive: true)
+/// Passwortfeldes), nicht beim App-Start. Ohne automatische Wiederholung:
+/// Schlägt das Laden fehl, prüft der Client nur die Länge (der Server
+/// erzwingt sie ebenfalls), statt das Absenden zu blockieren.
+@Riverpod(keepAlive: true, retry: _noRetry)
 Future<CommonPasswordList> commonPasswordList(Ref ref) =>
     const AssetCommonPasswordList().load();
 

app/lib/features/auth/presentation/providers/auth_providers.g.dart

@@ -94,13 +94,17 @@ final class AuthStatusProvider
 String _$authStatusHash() => r'4dc863db6fda2e17d84d0c3ed5c9bc1808630293';
 
 /// Liste häufiger Passwörter. Lazy: lädt erst beim ersten Lesen (Öffnen eines
-/// Passwortfeldes), nicht beim App-Start.
+/// Passwortfeldes), nicht beim App-Start. Ohne automatische Wiederholung:
+/// Schlägt das Laden fehl, prüft der Client nur die Länge (der Server
+/// erzwingt sie ebenfalls), statt das Absenden zu blockieren.
 
 @ProviderFor(commonPasswordList)
 final commonPasswordListProvider = CommonPasswordListProvider._();
 
 /// Liste häufiger Passwörter. Lazy: lädt erst beim ersten Lesen (Öffnen eines
-/// Passwortfeldes), nicht beim App-Start.
+/// Passwortfeldes), nicht beim App-Start. Ohne automatische Wiederholung:
+/// Schlägt das Laden fehl, prüft der Client nur die Länge (der Server
+/// erzwingt sie ebenfalls), statt das Absenden zu blockieren.
 
 final class CommonPasswordListProvider
     extends
@@ -113,12 +117,14 @@ final class CommonPasswordListProvider
         $FutureModifier<CommonPasswordList>,
         $FutureProvider<CommonPasswordList> {
   /// Liste häufiger Passwörter. Lazy: lädt erst beim ersten Lesen (Öffnen eines
-  /// Passwortfeldes), nicht beim App-Start.
+  /// Passwortfeldes), nicht beim App-Start. Ohne automatische Wiederholung:
+  /// Schlägt das Laden fehl, prüft der Client nur die Länge (der Server
+  /// erzwingt sie ebenfalls), statt das Absenden zu blockieren.
   CommonPasswordListProvider._()
     : super(
         from: null,
         argument: null,
-        retry: null,
+        retry: _noRetry,
         name: r'commonPasswordListProvider',
         isAutoDispose: false,
         dependencies: null,
@@ -141,7 +147,7 @@ final class CommonPasswordListProvider
 }
 
 String _$commonPasswordListHash() =>
-    r'964e79d4dc152c38ca77a55919cef3c14e5d3533';
+    r'39cdcf2bcde25bc7f4720c77feb7119febd2927f';
 
 @ProviderFor(registrationInputFactory)
 final registrationInputFactoryProvider = RegistrationInputFactoryProvider._();

app/lib/features/auth/presentation/register/register_controller.dart

@@ -0,0 +1,164 @@
+import 'dart:async';
+
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+import 'package:shuffle/core/config/app_config_provider.dart';
+import 'package:shuffle/core/logging/app_logger.dart';
+import 'package:shuffle/core/platform/url_opener.dart';
+import 'package:shuffle/features/auth/domain/auth_failure.dart';
+import 'package:shuffle/features/auth/domain/resend_origin.dart';
+import 'package:shuffle/features/auth/domain/validation/display_name_rule.dart';
+import 'package:shuffle/features/auth/domain/validation/email_format.dart';
+import 'package:shuffle/features/auth/presentation/providers/auth_providers.dart';
+import 'package:shuffle/features/auth/presentation/register/register_state.dart';
+
+part 'register_controller.g.dart';
+
+/// Legal texts linked from the consent checkbox.
+enum LegalDocument { privacy, terms }
+
+final _log = AppLogger('RegisterController');
+
+/// Logic of the registration form (KTO-01 Kriterien 1 bis 4 und 10).
+@riverpod
+class RegisterController extends _$RegisterController {
+  Future<void>? _commonPasswordsLoad;
+
+  @override
+  RegisterState build() => const RegisterState();
+
+  void emailChanged(String value) {
+    state = state.copyWith(email: value, serverEmailInvalid: false);
+  }
+
+  void passwordChanged(String value) {
+    // The password is checked while typing (Kriterium 3).
+    state = state.copyWith(
+      password: value,
+      visibleFields: {...state.visibleFields, RegisterField.password},
+      serverPasswordReasons: null,
+    );
+    unawaited(loadCommonPasswords());
+  }
+
+  void displayNameChanged(String value) {
+    state = state.copyWith(displayName: value);
+  }
+
+  void ageConfirmedChanged({required bool value}) {
+    state = state.copyWith(ageConfirmed: value);
+  }
+
+  void termsAcceptedChanged({required bool value}) {
+    state = state.copyWith(termsAccepted: value);
+  }
+
+  /// Field left: show its error (text fields only).
+  void fieldBlurred(RegisterField field) {
+    if (field == RegisterField.ageConfirmation ||
+        field == RegisterField.termsAcceptance) {
+      return;
+    }
+    state = state.copyWith(visibleFields: {...state.visibleFields, field});
+  }
+
+  /// Starts loading the list of common passwords (lazy, once). Called when
+  /// the password field is used.
+  Future<void> loadCommonPasswords() => _commonPasswordsLoad ??= _load();
+
+  Future<void> _load() async {
+    try {
+      final list = await ref.read(commonPasswordListProvider.future);
+      if (!ref.mounted) {
+        return;
+      }
+      state = state.copyWith(commonPasswords: list);
+    } on Object catch (error) {
+      // Fallback: only the length rule runs in the client; the server
+      // enforces the minimum length as well.
+      _log.warning('common password list unavailable: ${error.runtimeType}');
+    }
+  }
+
+  /// Validates and submits. Returns `true` if the screen should continue to
+  /// "check your inbox" (every 200 response, and `emailSendLimited`, F12).
+  Future<bool> submit() async {
+    if (state.isSubmitting) {
+      return false;
+    }
+    await loadCommonPasswords();
+    if (!ref.mounted) {
+      return false;
+    }
+
+    state = state.copyWith(
+      visibleFields: RegisterField.values.toSet(),
+      bannerFailure: null,
+      serverPasswordReasons: null,
+      serverEmailInvalid: false,
+      focusField: null,
+    );
+    final invalid = state.firstInvalidField;
+    if (invalid != null) {
+      state = state.copyWith(
+        focusField: invalid,
+        focusRequest: state.focusRequest + 1,
+      );
+      return false;
+    }
+
+    state = state.copyWith(status: RegisterStatus.submitting);
+    final input = ref.read(registrationInputFactoryProvider)(
+      email: EmailFormat.normalize(state.email),
+      password: state.password,
+      displayName: DisplayNameRule.normalize(state.displayName),
+      ageConfirmed: state.ageConfirmed,
+      termsAccepted: state.termsAccepted,
+    );
+    final result = await ref.read(authRepositoryProvider).signUp(input);
+    if (!ref.mounted) {
+      return false;
+    }
+
+    final failure = result.errorOrNull;
+    state = state.copyWith(status: RegisterStatus.editing);
+    if (failure == null || openEmailInputFailureFor(failure) == null) {
+      return true;
+    }
+    _showFailure(failure);
+    return false;
+  }
+
+  void _showFailure(AuthFailure failure) {
+    switch (failure) {
+      case WeakPassword(:final reasons):
+        state = state.copyWith(
+          serverPasswordReasons: reasons,
+          focusField: RegisterField.password,
+          focusRequest: state.focusRequest + 1,
+        );
+      case InvalidEmail():
+        state = state.copyWith(
+          serverEmailInvalid: true,
+          focusField: RegisterField.email,
+          focusRequest: state.focusRequest + 1,
+        );
+      default:
+        state = state.copyWith(bannerFailure: failure);
+    }
+  }
+
+  /// Opens a legal text in the browser. `false` if that did not work.
+  Future<bool> openLegalDocument(LegalDocument document) async {
+    final config = ref.read(appConfigProvider);
+    final url = switch (document) {
+      LegalDocument.privacy => config.legalPrivacyUrl,
+      LegalDocument.terms => config.legalTermsUrl,
+    };
+    final uri = Uri.tryParse(url);
+    if (uri == null || !uri.hasScheme) {
+      _log.warning('invalid legal url for ${document.name}');
+      return false;
+    }
+    return ref.read(urlOpenerProvider)(uri);
+  }
+}

app/lib/features/auth/presentation/register/register_controller.g.dart

@@ -0,0 +1,68 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'register_controller.dart';
+
+// **************************************************************************
+// RiverpodGenerator
+// **************************************************************************
+
+// GENERATED CODE - DO NOT MODIFY BY HAND
+// ignore_for_file: type=lint, type=warning
+/// Logic of the registration form (KTO-01 Kriterien 1 bis 4 und 10).
+
+@ProviderFor(RegisterController)
+final registerControllerProvider = RegisterControllerProvider._();
+
+/// Logic of the registration form (KTO-01 Kriterien 1 bis 4 und 10).
+final class RegisterControllerProvider
+    extends $NotifierProvider<RegisterController, RegisterState> {
+  /// Logic of the registration form (KTO-01 Kriterien 1 bis 4 und 10).
+  RegisterControllerProvider._()
+    : super(
+        from: null,
+        argument: null,
+        retry: null,
+        name: r'registerControllerProvider',
+        isAutoDispose: true,
+        dependencies: null,
+        $allTransitiveDependencies: null,
+      );
+
+  @override
+  String debugGetCreateSourceHash() => _$registerControllerHash();
+
+  @$internal
+  @override
+  RegisterController create() => RegisterController();
+
+  /// {@macro riverpod.override_with_value}
+  Override overrideWithValue(RegisterState value) {
+    return $ProviderOverride(
+      origin: this,
+      providerOverride: $SyncValueProvider<RegisterState>(value),
+    );
+  }
+}
+
+String _$registerControllerHash() =>
+    r'25930050b4b5fbaff535c3a09abe4ca15c860759';
+
+/// Logic of the registration form (KTO-01 Kriterien 1 bis 4 und 10).
+
+abstract class _$RegisterController extends $Notifier<RegisterState> {
+  RegisterState build();
+  @$mustCallSuper
+  @override
+  WhenComplete runBuild() {
+    final ref = this.ref as $Ref<RegisterState, RegisterState>;
+    final element =
+        ref.element
+            as $ClassProviderElement<
+              AnyNotifier<RegisterState, RegisterState>,
+              RegisterState,
+              Object?,
+              Object?
+            >;
+    return element.handleCreate(ref, build);
+  }
+}

app/lib/features/auth/presentation/register/register_screen.dart

@@ -0,0 +1,309 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:go_router/go_router.dart';
+import 'package:shuffle/core/l10n/l10n.dart';
+import 'package:shuffle/core/routing/app_routes.dart';
+import 'package:shuffle/core/theme/app_spacing.dart';
+import 'package:shuffle/core/widgets/app_banner.dart';
+import 'package:shuffle/core/widgets/app_checkbox_field.dart';
+import 'package:shuffle/core/widgets/app_form_scaffold.dart';
+import 'package:shuffle/core/widgets/app_password_field.dart';
+import 'package:shuffle/core/widgets/app_primary_button.dart';
+import 'package:shuffle/core/widgets/app_text_field.dart';
+import 'package:shuffle/features/auth/domain/auth_failure.dart';
+import 'package:shuffle/features/auth/domain/validation/display_name_rule.dart';
+import 'package:shuffle/features/auth/domain/validation/email_format.dart';
+import 'package:shuffle/features/auth/domain/validation/password_policy.dart';
+import 'package:shuffle/features/auth/presentation/auth_failure_texts.dart';
+import 'package:shuffle/features/auth/presentation/register/register_controller.dart';
+import 'package:shuffle/features/auth/presentation/register/register_state.dart';
+import 'package:shuffle/features/auth/presentation/widgets/auth_screen_title.dart';
+
+/// Registration (`/register`, KTO-01 Kriterien 1 bis 4 und 10, QUE-04
+/// Kriterium 1). Only shows state and forwards input to the
+/// [RegisterController].
+class RegisterScreen extends ConsumerStatefulWidget {
+  const RegisterScreen({super.key});
+
+  @override
+  ConsumerState<RegisterScreen> createState() => _RegisterScreenState();
+}
+
+class _RegisterScreenState extends ConsumerState<RegisterScreen> {
+  final _email = TextEditingController();
+  final _password = TextEditingController();
+  final _displayName = TextEditingController();
+  final _emailFocus = FocusNode();
+  final _passwordFocus = FocusNode();
+  final _displayNameFocus = FocusNode();
+
+  @override
+  void initState() {
+    super.initState();
+    _emailFocus.addListener(
+      () => _onFocusChange(_emailFocus, RegisterField.email),
+    );
+    _passwordFocus.addListener(() {
+      if (_passwordFocus.hasFocus) {
+        // The list of common passwords loads lazily on first use.
+        unawaited(
+          ref.read(registerControllerProvider.notifier).loadCommonPasswords(),
+        );
+      }
+      _onFocusChange(_passwordFocus, RegisterField.password);
+    });
+    _displayNameFocus.addListener(
+      () => _onFocusChange(_displayNameFocus, RegisterField.displayName),
+    );
+  }
+
+  void _onFocusChange(FocusNode node, RegisterField field) {
+    if (!node.hasFocus) {
+      ref.read(registerControllerProvider.notifier).fieldBlurred(field);
+    }
+  }
+
+  @override
+  void dispose() {
+    _email.dispose();
+    _password.dispose();
+    _displayName.dispose();
+    _emailFocus.dispose();
+    _passwordFocus.dispose();
+    _displayNameFocus.dispose();
+    super.dispose();
+  }
+
+  Future<void> _submit() async {
+    final controller = ref.read(registerControllerProvider.notifier);
+    final succeeded = await controller.submit();
+    if (!mounted || !succeeded) {
+      return;
+    }
+    final email = EmailFormat.normalize(
+      ref.read(registerControllerProvider).email,
+    );
+    TextInput.finishAutofillContext();
+    context.go(AppRoutes.registerCheckEmail, extra: email);
+  }
+
+  Future<void> _openLegal(LegalDocument document) async {
+    final opened = await ref
+        .read(registerControllerProvider.notifier)
+        .openLegalDocument(document);
+    if (!mounted || opened) {
+      return;
+    }
+    ScaffoldMessenger.of(
+      context,
+    ).showSnackBar(SnackBar(content: Text(context.l10n.authErrorUnexpected)));
+  }
+
+  void _requestFocus(RegisterField? field) {
+    final node = switch (field) {
+      RegisterField.email => _emailFocus,
+      RegisterField.password => _passwordFocus,
+      RegisterField.displayName => _displayNameFocus,
+      _ => null,
+    };
+    node?.requestFocus();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    ref.listen(registerControllerProvider, (previous, next) {
+      if (previous?.focusRequest != next.focusRequest) {
+        _requestFocus(next.focusField);
+      }
+    });
+    final state = ref.watch(registerControllerProvider);
+    final controller = ref.read(registerControllerProvider.notifier);
+    final l10n = context.l10n;
+    final busy = state.isSubmitting;
+
+    return AppFormScaffold(
+      key: const Key('register_screen'),
+      child: AutofillGroup(
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.stretch,
+          children: [
+            AuthScreenTitle(l10n.authRegisterTitle),
+            if (state.bannerFailure case final failure?) ...[
+              const SizedBox(height: AppSpacing.lg),
+              _FailureBanner(
+                key: const Key('register_banner'),
+                failure: failure,
+                onRetry: busy ? null : _submit,
+              ),
+            ],
+            const SizedBox(height: AppSpacing.xl),
+            AppTextField(
+              key: const Key('register_email'),
+              label: l10n.authFieldEmailLabel,
+              controller: _email,
+              focusNode: _emailFocus,
+              keyboardType: TextInputType.emailAddress,
+              textInputAction: TextInputAction.next,
+              autofillHints: const [AutofillHints.email],
+              autocorrect: false,
+              enableSuggestions: false,
+              enabled: !busy,
+              errorText: _emailError(l10n, state),
+              onChanged: controller.emailChanged,
+            ),
+            const SizedBox(height: AppSpacing.lg),
+            AppPasswordField(
+              key: const Key('register_password'),
+              label: l10n.authFieldPasswordLabel,
+              showPasswordLabel: l10n.authPasswordShow,
+              hidePasswordLabel: l10n.authPasswordHide,
+              controller: _password,
+              focusNode: _passwordFocus,
+              isNewPassword: true,
+              textInputAction: TextInputAction.next,
+              enabled: !busy,
+              ruleHint: l10n.authPasswordRule,
+              errorText: _passwordError(l10n, state),
+              onChanged: controller.passwordChanged,
+            ),
+            const SizedBox(height: AppSpacing.lg),
+            AppTextField(
+              key: const Key('register_display_name'),
+              label: l10n.authFieldDisplayNameLabel,
+              controller: _displayName,
+              focusNode: _displayNameFocus,
+              textInputAction: TextInputAction.done,
+              textCapitalization: TextCapitalization.words,
+              autofillHints: const [AutofillHints.nickname],
+              maxLength: DisplayNameRule.maxLength,
+              showCounter: true,
+              counterText: l10n.authDisplayNameCounter(
+                state.displayNameLength,
+                DisplayNameRule.maxLength,
+              ),
+              enabled: !busy,
+              errorText: _displayNameError(l10n, state),
+              onChanged: controller.displayNameChanged,
+              onSubmitted: (_) {
+                if (!busy) {
+                  unawaited(_submit());
+                }
+              },
+            ),
+            const SizedBox(height: AppSpacing.lg),
+            AppCheckboxField(
+              key: const Key('register_age_checkbox'),
+              value: state.ageConfirmed,
+              label: l10n.authCheckboxAgeLabel,
+              enabled: !busy,
+              errorText: state.shownAgeError ? l10n.authAgeNotConfirmed : null,
+              onChanged: (value) =>
+                  controller.ageConfirmedChanged(value: value),
+            ),
+            AppCheckboxField.rich(
+              key: const Key('register_terms_checkbox'),
+              value: state.termsAccepted,
+              enabled: !busy,
+              segments: _termsSegments(l10n),
+              errorText: state.shownTermsError
+                  ? l10n.authTermsNotAccepted
+                  : null,
+              onChanged: (value) =>
+                  controller.termsAcceptedChanged(value: value),
+            ),
+            const SizedBox(height: AppSpacing.xl),
+            AppPrimaryButton(
+              key: const Key('register_submit'),
+              label: l10n.authRegisterSubmit,
+              loadingLabel: l10n.authSubmitting,
+              isLoading: busy,
+              onPressed: _submit,
+            ),
+            const SizedBox(height: AppSpacing.sm),
+            TextButton(
+              key: const Key('register_login_link'),
+              onPressed: busy ? null : () => context.go(AppRoutes.login),
+              child: Text(l10n.authRegisterHaveAccount),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  List<AppLabelSegment> _termsSegments(AppLocalizations l10n) {
+    final suffix = l10n.authCheckboxTermsSuffix;
+    return [
+      AppLabelSegment.text('${l10n.authCheckboxTermsPrefix} '),
+      AppLabelSegment.link(
+        l10n.authCheckboxTermsPrivacyLink,
+        () => _openLegal(LegalDocument.privacy),
+      ),
+      AppLabelSegment.text(' ${l10n.authCheckboxTermsMiddle} '),
+      AppLabelSegment.link(
+        l10n.authCheckboxTermsTermsLink,
+        () => _openLegal(LegalDocument.terms),
+      ),
+      if (suffix.isNotEmpty) AppLabelSegment.text(' $suffix'),
+    ];
+  }
+
+  String? _emailError(AppLocalizations l10n, RegisterState state) {
+    if (state.serverEmailInvalid || state.shownEmailError != null) {
+      return l10n.authErrorEmailInvalid;
+    }
+    return null;
+  }
+
+  String? _passwordError(AppLocalizations l10n, RegisterState state) {
+    if (state.serverPasswordReasons case final reasons?) {
+      return weakPasswordMessage(l10n, reasons);
+    }
+    if (state.shownPasswordRequired) {
+      return l10n.authPasswordRequired;
+    }
+    return switch (state.shownPasswordError) {
+      PasswordTooShort(:final missing) => l10n.authPasswordTooShort(missing),
+      PasswordCommon() => l10n.authPasswordCommon,
+      null => null,
+    };
+  }
+
+  String? _displayNameError(AppLocalizations l10n, RegisterState state) =>
+      switch (state.shownDisplayNameError) {
+        DisplayNameError.empty => l10n.authDisplayNameEmpty,
+        DisplayNameError.tooLong => l10n.authDisplayNameTooLong(
+          DisplayNameRule.maxLength,
+        ),
+        // U+200B: same message as "invalid" (Spec #1 § 5.4).
+        DisplayNameError.invalidCharacter => l10n.authDisplayNameInvalid,
+        null => null,
+      };
+}
+
+class _FailureBanner extends StatelessWidget {
+  const _FailureBanner({
+    required this.failure,
+    required this.onRetry,
+    super.key,
+  });
+
+  final AuthFailure failure;
+  final VoidCallback? onRetry;
+
+  @override
+  Widget build(BuildContext context) {
+    final l10n = context.l10n;
+    final retryable = failure is NetworkFailure || failure is Unexpected;
+    return AppBanner(
+      type: AppBannerType.error,
+      typeLabel: l10n.authBannerTypeError,
+      message: authFailureMessage(l10n, failure),
+      actionLabel: retryable && onRetry != null ? l10n.authActionRetry : null,
+      onAction: retryable ? onRetry : null,
+    );
+  }
+}

app/lib/features/auth/presentation/register/register_state.dart

@@ -0,0 +1,115 @@
+import 'package:freezed_annotation/freezed_annotation.dart';
+import 'package:shuffle/features/auth/domain/auth_failure.dart';
+import 'package:shuffle/features/auth/domain/validation/common_passwords.dart';
+import 'package:shuffle/features/auth/domain/validation/display_name_rule.dart';
+import 'package:shuffle/features/auth/domain/validation/email_format.dart';
+import 'package:shuffle/features/auth/domain/validation/password_policy.dart';
+
+part 'register_state.freezed.dart';
+
+/// Form fields of the registration, in reading order.
+enum RegisterField {
+  email,
+  password,
+  displayName,
+  ageConfirmation,
+  termsAcceptance,
+}
+
+enum RegisterStatus { editing, submitting }
+
+/// Values, visibility of errors and submit state of the registration form.
+///
+/// Errors are derived from the values by the domain rules. Which of them are
+/// shown is decided by [visibleFields] (blur, typing in the password field,
+/// submit attempt).
+@freezed
+abstract class RegisterState with _$RegisterState {
+  const factory RegisterState({
+    @Default('') String email,
+    @Default('') String password,
+    @Default('') String displayName,
+    @Default(false) bool ageConfirmed,
+    @Default(false) bool termsAccepted,
+    @Default(<RegisterField>{}) Set<RegisterField> visibleFields,
+    @Default(RegisterStatus.editing) RegisterStatus status,
+
+    /// Loaded lazily with the first use of the password field.
+    CommonPasswordList? commonPasswords,
+
+    /// General failure shown as banner.
+    AuthFailure? bannerFailure,
+
+    /// `weak_password` reasons reported by the server, shown at the password.
+    List<WeakPasswordReason>? serverPasswordReasons,
+
+    /// The server rejected the address syntax; shown at the email field.
+    @Default(false) bool serverEmailInvalid,
+
+    /// Field that should receive focus after a failed submit.
+    RegisterField? focusField,
+
+    /// Incremented whenever [focusField] is set, so the screen can react
+    /// to repeated requests for the same field.
+    @Default(0) int focusRequest,
+  }) = _RegisterState;
+
+  const RegisterState._();
+
+  bool get isSubmitting => status == RegisterStatus.submitting;
+
+  EmailError? get emailError => EmailFormat.validate(email);
+
+  PasswordError? get passwordError =>
+      PasswordPolicy.validate(password, common: commonPasswords);
+
+  DisplayNameError? get displayNameError =>
+      DisplayNameRule.validate(displayName);
+
+  int get displayNameLength => DisplayNameRule.length(displayName);
+
+  bool get ageError => !ageConfirmed;
+
+  bool get termsError => !termsAccepted;
+
+  bool isVisible(RegisterField field) => visibleFields.contains(field);
+
+  /// Local error of [field] (ignoring visibility).
+  bool hasError(RegisterField field) => switch (field) {
+    RegisterField.email => emailError != null,
+    RegisterField.password => password.isEmpty || passwordError != null,
+    RegisterField.displayName => displayNameError != null,
+    RegisterField.ageConfirmation => ageError,
+    RegisterField.termsAcceptance => termsError,
+  };
+
+  RegisterField? get firstInvalidField {
+    for (final field in RegisterField.values) {
+      if (hasError(field)) {
+        return field;
+      }
+    }
+    return null;
+  }
+
+  // Errors as the screen shows them.
+
+  EmailError? get shownEmailError =>
+      isVisible(RegisterField.email) ? emailError : null;
+
+  /// Empty password is "required", otherwise the policy error.
+  bool get shownPasswordRequired =>
+      isVisible(RegisterField.password) && password.isEmpty;
+
+  PasswordError? get shownPasswordError =>
+      isVisible(RegisterField.password) ? passwordError : null;
+
+  DisplayNameError? get shownDisplayNameError =>
+      isVisible(RegisterField.displayName) ? displayNameError : null;
+
+  bool get shownAgeError =>
+      isVisible(RegisterField.ageConfirmation) && ageError;
+
+  bool get shownTermsError =>
+      isVisible(RegisterField.termsAcceptance) && termsError;
+}

app/lib/features/auth/presentation/register/register_state.freezed.dart

@@ -0,0 +1,368 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+// coverage:ignore-file
+// ignore_for_file: type=lint, type=warning, deprecated_member_use, deprecated_member_use_from_same_package
+// ignore_for_file: unused_element, deprecated_member_use, deprecated_member_use_from_same_package, use_function_type_syntax_for_parameters, unnecessary_const, avoid_init_to_null, invalid_override_different_default_values_named, prefer_expression_function_bodies, annotate_overrides, invalid_annotation_target, unnecessary_question_mark
+
+part of 'register_state.dart';
+
+// **************************************************************************
+// FreezedGenerator
+// **************************************************************************
+
+// GENERATED CODE - DO NOT MODIFY BY HAND
+// dart format off
+T _$identity<T>(T value) => value;
+/// @nodoc
+mixin _$RegisterState {
+
+ String get email; String get password; String get displayName; bool get ageConfirmed; bool get termsAccepted; Set<RegisterField> get visibleFields; RegisterStatus get status;/// Loaded lazily with the first use of the password field.
+ CommonPasswordList? get commonPasswords;/// General failure shown as banner.
+ AuthFailure? get bannerFailure;/// `weak_password` reasons reported by the server, shown at the password.
+ List<WeakPasswordReason>? get serverPasswordReasons;/// The server rejected the address syntax; shown at the email field.
+ bool get serverEmailInvalid;/// Field that should receive focus after a failed submit.
+ RegisterField? get focusField;/// Incremented whenever [focusField] is set, so the screen can react
+/// to repeated requests for the same field.
+ int get focusRequest;
+/// Create a copy of RegisterState
+/// with the given fields replaced by the non-null parameter values.
+@JsonKey(includeFromJson: false, includeToJson: false)
+@pragma('vm:prefer-inline')
+$RegisterStateCopyWith<RegisterState> get copyWith => _$RegisterStateCopyWithImpl<RegisterState>(this as RegisterState, _$identity);
+
+
+
+@override
+bool operator ==(Object other) {
+  final _this = this as RegisterState;
+  return identical(this, other) || (other.runtimeType == runtimeType&&other is RegisterState&&(identical(other.email, _this.email) || other.email == _this.email)&&(identical(other.password, _this.password) || other.password == _this.password)&&(identical(other.displayName, _this.displayName) || other.displayName == _this.displayName)&&(identical(other.ageConfirmed, _this.ageConfirmed) || other.ageConfirmed == _this.ageConfirmed)&&(identical(other.termsAccepted, _this.termsAccepted) || other.termsAccepted == _this.termsAccepted)&&const DeepCollectionEquality().equals(other.visibleFields, _this.visibleFields)&&(identical(other.status, _this.status) || other.status == _this.status)&&(identical(other.commonPasswords, _this.commonPasswords) || other.commonPasswords == _this.commonPasswords)&&(identical(other.bannerFailure, _this.bannerFailure) || other.bannerFailure == _this.bannerFailure)&&const DeepCollectionEquality().equals(other.serverPasswordReasons, _this.serverPasswordReasons)&&(identical(other.serverEmailInvalid, _this.serverEmailInvalid) || other.serverEmailInvalid == _this.serverEmailInvalid)&&(identical(other.focusField, _this.focusField) || other.focusField == _this.focusField)&&(identical(other.focusRequest, _this.focusRequest) || other.focusRequest == _this.focusRequest));
+}
+
+
+@override
+int get hashCode {
+  final _this = this as RegisterState;
+  return Object.hash(runtimeType,_this.email,_this.password,_this.displayName,_this.ageConfirmed,_this.termsAccepted,const DeepCollectionEquality().hash(_this.visibleFields),_this.status,_this.commonPasswords,_this.bannerFailure,const DeepCollectionEquality().hash(_this.serverPasswordReasons),_this.serverEmailInvalid,_this.focusField,_this.focusRequest);
+}
+
+@override
+String toString() {
+  final _this = this as RegisterState;
+  return 'RegisterState(email: ${_this.email}, password: ${_this.password}, displayName: ${_this.displayName}, ageConfirmed: ${_this.ageConfirmed}, termsAccepted: ${_this.termsAccepted}, visibleFields: ${_this.visibleFields}, status: ${_this.status}, commonPasswords: ${_this.commonPasswords}, bannerFailure: ${_this.bannerFailure}, serverPasswordReasons: ${_this.serverPasswordReasons}, serverEmailInvalid: ${_this.serverEmailInvalid}, focusField: ${_this.focusField}, focusRequest: ${_this.focusRequest})';
+}
+
+
+}
+
+/// @nodoc
+abstract mixin class $RegisterStateCopyWith<$Res>  {
+  factory $RegisterStateCopyWith(RegisterState value, $Res Function(RegisterState) _then) = _$RegisterStateCopyWithImpl;
+@useResult
+$Res call({
+ String email, String password, String displayName, bool ageConfirmed, bool termsAccepted, Set<RegisterField> visibleFields, RegisterStatus status, CommonPasswordList? commonPasswords, AuthFailure? bannerFailure, List<WeakPasswordReason>? serverPasswordReasons, bool serverEmailInvalid, RegisterField? focusField, int focusRequest
+});
+
+
+$AuthFailureCopyWith<$Res>? get bannerFailure;
+
+}
+/// @nodoc
+class _$RegisterStateCopyWithImpl<$Res>
+    implements $RegisterStateCopyWith<$Res> {
+  _$RegisterStateCopyWithImpl(this._self, this._then);
+
+  final RegisterState _self;
+  final $Res Function(RegisterState) _then;
+
+/// Create a copy of RegisterState
+/// with the given fields replaced by the non-null parameter values.
+@pragma('vm:prefer-inline') @override $Res call({Object? email = null,Object? password = null,Object? displayName = null,Object? ageConfirmed = null,Object? termsAccepted = null,Object? visibleFields = null,Object? status = null,Object? commonPasswords = freezed,Object? bannerFailure = freezed,Object? serverPasswordReasons = freezed,Object? serverEmailInvalid = null,Object? focusField = freezed,Object? focusRequest = null,}) {
+  return _then(RegisterState(
+email: null == email ? _self.email : email // ignore: cast_nullable_to_non_nullable
+as String,password: null == password ? _self.password : password // ignore: cast_nullable_to_non_nullable
+as String,displayName: null == displayName ? _self.displayName : displayName // ignore: cast_nullable_to_non_nullable
+as String,ageConfirmed: null == ageConfirmed ? _self.ageConfirmed : ageConfirmed // ignore: cast_nullable_to_non_nullable
+as bool,termsAccepted: null == termsAccepted ? _self.termsAccepted : termsAccepted // ignore: cast_nullable_to_non_nullable
+as bool,visibleFields: null == visibleFields ? _self.visibleFields : visibleFields // ignore: cast_nullable_to_non_nullable
+as Set<RegisterField>,status: null == status ? _self.status : status // ignore: cast_nullable_to_non_nullable
+as RegisterStatus,commonPasswords: freezed == commonPasswords ? _self.commonPasswords : commonPasswords // ignore: cast_nullable_to_non_nullable
+as CommonPasswordList?,bannerFailure: freezed == bannerFailure ? _self.bannerFailure : bannerFailure // ignore: cast_nullable_to_non_nullable
+as AuthFailure?,serverPasswordReasons: freezed == serverPasswordReasons ? _self.serverPasswordReasons : serverPasswordReasons // ignore: cast_nullable_to_non_nullable
+as List<WeakPasswordReason>?,serverEmailInvalid: null == serverEmailInvalid ? _self.serverEmailInvalid : serverEmailInvalid // ignore: cast_nullable_to_non_nullable
+as bool,focusField: freezed == focusField ? _self.focusField : focusField // ignore: cast_nullable_to_non_nullable
+as RegisterField?,focusRequest: null == focusRequest ? _self.focusRequest : focusRequest // ignore: cast_nullable_to_non_nullable
+as int,
+  ));
+}
+/// Create a copy of RegisterState
+/// with the given fields replaced by the non-null parameter values.
+@override
+@pragma('vm:prefer-inline')
+$AuthFailureCopyWith<$Res>? get bannerFailure {
+    if (_self.bannerFailure == null) {
+    return null;
+  }
+
+  return $AuthFailureCopyWith<$Res>(_self.bannerFailure!, (value) {
+    return _then(_self.copyWith(bannerFailure: value));
+  });
+}
+}
+
+
+/// Adds pattern-matching-related methods to [RegisterState].
+extension RegisterStatePatterns on RegisterState {
+/// A variant of `map` that fallback to returning `orElse`.
+///
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case final Subclass value:
+///     return ...;
+///   case _:
+///     return orElse();
+/// }
+/// ```
+
+@optionalTypeArgs TResult maybeMap<TResult extends Object?>(TResult Function( _RegisterState value)?  $default,{required TResult orElse(),}){
+final _that = this;
+switch (_that) {
+case _RegisterState() when $default != null:
+return $default(_that);case _:
+  return orElse();
+
+}
+}
+/// A `switch`-like method, using callbacks.
+///
+/// Callbacks receives the raw object, upcasted.
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case final Subclass value:
+///     return ...;
+///   case final Subclass2 value:
+///     return ...;
+/// }
+/// ```
+
+@optionalTypeArgs TResult map<TResult extends Object?>(TResult Function( _RegisterState value)  $default,){
+final _that = this;
+switch (_that) {
+case _RegisterState():
+return $default(_that);case _:
+  throw StateError('Unexpected subclass');
+
+}
+}
+/// A variant of `map` that fallback to returning `null`.
+///
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case final Subclass value:
+///     return ...;
+///   case _:
+///     return null;
+/// }
+/// ```
+
+@optionalTypeArgs TResult? mapOrNull<TResult extends Object?>(TResult? Function( _RegisterState value)?  $default,){
+final _that = this;
+switch (_that) {
+case _RegisterState() when $default != null:
+return $default(_that);case _:
+  return null;
+
+}
+}
+/// A variant of `when` that fallback to an `orElse` callback.
+///
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case Subclass(:final field):
+///     return ...;
+///   case _:
+///     return orElse();
+/// }
+/// ```
+
+@optionalTypeArgs TResult maybeWhen<TResult extends Object?>(TResult Function( String email,  String password,  String displayName,  bool ageConfirmed,  bool termsAccepted,  Set<RegisterField> visibleFields,  RegisterStatus status,  CommonPasswordList? commonPasswords,  AuthFailure? bannerFailure,  List<WeakPasswordReason>? serverPasswordReasons,  bool serverEmailInvalid,  RegisterField? focusField,  int focusRequest)?  $default,{required TResult orElse(),}) {final _that = this;
+switch (_that) {
+case _RegisterState() when $default != null:
+return $default(_that.email,_that.password,_that.displayName,_that.ageConfirmed,_that.termsAccepted,_that.visibleFields,_that.status,_that.commonPasswords,_that.bannerFailure,_that.serverPasswordReasons,_that.serverEmailInvalid,_that.focusField,_that.focusRequest);case _:
+  return orElse();
+
+}
+}
+/// A `switch`-like method, using callbacks.
+///
+/// As opposed to `map`, this offers destructuring.
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case Subclass(:final field):
+///     return ...;
+///   case Subclass2(:final field2):
+///     return ...;
+/// }
+/// ```
+
+@optionalTypeArgs TResult when<TResult extends Object?>(TResult Function( String email,  String password,  String displayName,  bool ageConfirmed,  bool termsAccepted,  Set<RegisterField> visibleFields,  RegisterStatus status,  CommonPasswordList? commonPasswords,  AuthFailure? bannerFailure,  List<WeakPasswordReason>? serverPasswordReasons,  bool serverEmailInvalid,  RegisterField? focusField,  int focusRequest)  $default,) {final _that = this;
+switch (_that) {
+case _RegisterState():
+return $default(_that.email,_that.password,_that.displayName,_that.ageConfirmed,_that.termsAccepted,_that.visibleFields,_that.status,_that.commonPasswords,_that.bannerFailure,_that.serverPasswordReasons,_that.serverEmailInvalid,_that.focusField,_that.focusRequest);case _:
+  throw StateError('Unexpected subclass');
+
+}
+}
+/// A variant of `when` that fallback to returning `null`
+///
+/// It is equivalent to doing:
+/// ```dart
+/// switch (sealedClass) {
+///   case Subclass(:final field):
+///     return ...;
+///   case _:
+///     return null;
+/// }
+/// ```
+
+@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>(TResult? Function( String email,  String password,  String displayName,  bool ageConfirmed,  bool termsAccepted,  Set<RegisterField> visibleFields,  RegisterStatus status,  CommonPasswordList? commonPasswords,  AuthFailure? bannerFailure,  List<WeakPasswordReason>? serverPasswordReasons,  bool serverEmailInvalid,  RegisterField? focusField,  int focusRequest)?  $default,) {final _that = this;
+switch (_that) {
+case _RegisterState() when $default != null:
+return $default(_that.email,_that.password,_that.displayName,_that.ageConfirmed,_that.termsAccepted,_that.visibleFields,_that.status,_that.commonPasswords,_that.bannerFailure,_that.serverPasswordReasons,_that.serverEmailInvalid,_that.focusField,_that.focusRequest);case _:
+  return null;
+
+}
+}
+
+}
+
+/// @nodoc
+
+
+class _RegisterState extends RegisterState {
+  const _RegisterState({this.email = '', this.password = '', this.displayName = '', this.ageConfirmed = false, this.termsAccepted = false,  Set<RegisterField> visibleFields = const <RegisterField>{}, this.status = RegisterStatus.editing, this.commonPasswords, this.bannerFailure,  List<WeakPasswordReason>? serverPasswordReasons, this.serverEmailInvalid = false, this.focusField, this.focusRequest = 0}): _visibleFields = visibleFields,_serverPasswordReasons = serverPasswordReasons,super._();
+  
+
+@override@JsonKey() final  String email;
+@override@JsonKey() final  String password;
+@override@JsonKey() final  String displayName;
+@override@JsonKey() final  bool ageConfirmed;
+@override@JsonKey() final  bool termsAccepted;
+ final  Set<RegisterField> _visibleFields;
+@override@JsonKey() Set<RegisterField> get visibleFields {
+  if (_visibleFields is EqualUnmodifiableSetView) return _visibleFields;
+  // ignore: implicit_dynamic_type
+  return EqualUnmodifiableSetView(_visibleFields);
+}
+
+@override@JsonKey() final  RegisterStatus status;
+/// Loaded lazily with the first use of the password field.
+@override final  CommonPasswordList? commonPasswords;
+/// General failure shown as banner.
+@override final  AuthFailure? bannerFailure;
+/// `weak_password` reasons reported by the server, shown at the password.
+ final  List<WeakPasswordReason>? _serverPasswordReasons;
+/// `weak_password` reasons reported by the server, shown at the password.
+@override List<WeakPasswordReason>? get serverPasswordReasons {
+  final value = _serverPasswordReasons;
+  if (value == null) return null;
+  if (_serverPasswordReasons is EqualUnmodifiableListView) return _serverPasswordReasons;
+  // ignore: implicit_dynamic_type
+  return EqualUnmodifiableListView(value);
+}
+
+/// The server rejected the address syntax; shown at the email field.
+@override@JsonKey() final  bool serverEmailInvalid;
+/// Field that should receive focus after a failed submit.
+@override final  RegisterField? focusField;
+/// Incremented whenever [focusField] is set, so the screen can react
+/// to repeated requests for the same field.
+@override@JsonKey() final  int focusRequest;
+
+/// Create a copy of RegisterState
+/// with the given fields replaced by the non-null parameter values.
+@override @JsonKey(includeFromJson: false, includeToJson: false)
+@pragma('vm:prefer-inline')
+_$RegisterStateCopyWith<_RegisterState> get copyWith => __$RegisterStateCopyWithImpl<_RegisterState>(this, _$identity);
+
+
+
+@override
+bool operator ==(Object other) {
+    return identical(this, other) || (other.runtimeType == runtimeType&&other is _RegisterState&&(identical(other.email, email) || other.email == email)&&(identical(other.password, password) || other.password == password)&&(identical(other.displayName, displayName) || other.displayName == displayName)&&(identical(other.ageConfirmed, ageConfirmed) || other.ageConfirmed == ageConfirmed)&&(identical(other.termsAccepted, termsAccepted) || other.termsAccepted == termsAccepted)&&const DeepCollectionEquality().equals(other.visibleFields, _visibleFields)&&(identical(other.status, status) || other.status == status)&&(identical(other.commonPasswords, commonPasswords) || other.commonPasswords == commonPasswords)&&(identical(other.bannerFailure, bannerFailure) || other.bannerFailure == bannerFailure)&&const DeepCollectionEquality().equals(other.serverPasswordReasons, _serverPasswordReasons)&&(identical(other.serverEmailInvalid, serverEmailInvalid) || other.serverEmailInvalid == serverEmailInvalid)&&(identical(other.focusField, focusField) || other.focusField == focusField)&&(identical(other.focusRequest, focusRequest) || other.focusRequest == focusRequest));
+}
+
+
+@override
+int get hashCode {
+    return Object.hash(runtimeType,email,password,displayName,ageConfirmed,termsAccepted,const DeepCollectionEquality().hash(_visibleFields),status,commonPasswords,bannerFailure,const DeepCollectionEquality().hash(_serverPasswordReasons),serverEmailInvalid,focusField,focusRequest);
+}
+
+@override
+String toString() {
+    return 'RegisterState(email: $email, password: $password, displayName: $displayName, ageConfirmed: $ageConfirmed, termsAccepted: $termsAccepted, visibleFields: $visibleFields, status: $status, commonPasswords: $commonPasswords, bannerFailure: $bannerFailure, serverPasswordReasons: $serverPasswordReasons, serverEmailInvalid: $serverEmailInvalid, focusField: $focusField, focusRequest: $focusRequest)';
+}
+
+
+}
+
+/// @nodoc
+abstract mixin class _$RegisterStateCopyWith<$Res> implements $RegisterStateCopyWith<$Res> {
+  factory _$RegisterStateCopyWith(_RegisterState value, $Res Function(_RegisterState) _then) = __$RegisterStateCopyWithImpl;
+@override @useResult
+$Res call({
+ String email, String password, String displayName, bool ageConfirmed, bool termsAccepted, Set<RegisterField> visibleFields, RegisterStatus status, CommonPasswordList? commonPasswords, AuthFailure? bannerFailure, List<WeakPasswordReason>? serverPasswordReasons, bool serverEmailInvalid, RegisterField? focusField, int focusRequest
+});
+
+
+@override $AuthFailureCopyWith<$Res>? get bannerFailure;
+
+}
+/// @nodoc
+class __$RegisterStateCopyWithImpl<$Res>
+    implements _$RegisterStateCopyWith<$Res> {
+  __$RegisterStateCopyWithImpl(this._self, this._then);
+
+  final _RegisterState _self;
+  final $Res Function(_RegisterState) _then;
+
+/// Create a copy of RegisterState
+/// with the given fields replaced by the non-null parameter values.
+@override @pragma('vm:prefer-inline') $Res call({Object? email = null,Object? password = null,Object? displayName = null,Object? ageConfirmed = null,Object? termsAccepted = null,Object? visibleFields = null,Object? status = null,Object? commonPasswords = freezed,Object? bannerFailure = freezed,Object? serverPasswordReasons = freezed,Object? serverEmailInvalid = null,Object? focusField = freezed,Object? focusRequest = null,}) {
+  return _then(_RegisterState(
+email: null == email ? _self.email : email // ignore: cast_nullable_to_non_nullable
+as String,password: null == password ? _self.password : password // ignore: cast_nullable_to_non_nullable
+as String,displayName: null == displayName ? _self.displayName : displayName // ignore: cast_nullable_to_non_nullable
+as String,ageConfirmed: null == ageConfirmed ? _self.ageConfirmed : ageConfirmed // ignore: cast_nullable_to_non_nullable
+as bool,termsAccepted: null == termsAccepted ? _self.termsAccepted : termsAccepted // ignore: cast_nullable_to_non_nullable
+as bool,visibleFields: null == visibleFields ? _self._visibleFields : visibleFields // ignore: cast_nullable_to_non_nullable
+as Set<RegisterField>,status: null == status ? _self.status : status // ignore: cast_nullable_to_non_nullable
+as RegisterStatus,commonPasswords: freezed == commonPasswords ? _self.commonPasswords : commonPasswords // ignore: cast_nullable_to_non_nullable
+as CommonPasswordList?,bannerFailure: freezed == bannerFailure ? _self.bannerFailure : bannerFailure // ignore: cast_nullable_to_non_nullable
+as AuthFailure?,serverPasswordReasons: freezed == serverPasswordReasons ? _self._serverPasswordReasons : serverPasswordReasons // ignore: cast_nullable_to_non_nullable
+as List<WeakPasswordReason>?,serverEmailInvalid: null == serverEmailInvalid ? _self.serverEmailInvalid : serverEmailInvalid // ignore: cast_nullable_to_non_nullable
+as bool,focusField: freezed == focusField ? _self.focusField : focusField // ignore: cast_nullable_to_non_nullable
+as RegisterField?,focusRequest: null == focusRequest ? _self.focusRequest : focusRequest // ignore: cast_nullable_to_non_nullable
+as int,
+  ));
+}
+
+/// Create a copy of RegisterState
+/// with the given fields replaced by the non-null parameter values.
+@override
+@pragma('vm:prefer-inline')
+$AuthFailureCopyWith<$Res>? get bannerFailure {
+    if (_self.bannerFailure == null) {
+    return null;
+  }
+
+  return $AuthFailureCopyWith<$Res>(_self.bannerFailure!, (value) {
+    return _then(_self.copyWith(bannerFailure: value));
+  });
+}
+}
+
+// dart format on

app/lib/features/auth/presentation/widgets/auth_screen_title.dart

@@ -0,0 +1,16 @@
+import 'package:flutter/material.dart';
+
+/// Screen title as heading for screen readers (design: `headlineSmall`).
+class AuthScreenTitle extends StatelessWidget {
+  const AuthScreenTitle(this.title, {super.key});
+
+  final String title;
+
+  @override
+  Widget build(BuildContext context) {
+    return Semantics(
+      header: true,
+      child: Text(title, style: Theme.of(context).textTheme.headlineSmall),
+    );
+  }
+}

app/lib/l10n/app_de.arb

@@ -4,5 +4,64 @@
   "homePlaceholderMessage": "Willkommen bei Shuffle. Der Brettspielkatalog folgt in Kürze.",
   "notFoundTitle": "Seite nicht gefunden",
   "notFoundMessage": "Diese Seite existiert nicht oder wurde verschoben.",
-  "notFoundBackHome": "Zurück zum Start"
+  "notFoundBackHome": "Zurück zum Start",
+  "authErrorInvalidCredentials": "E-Mail-Adresse oder Passwort ist nicht korrekt.",
+  "authErrorEmailNotConfirmed": "Bestätige zuerst deine E-Mail-Adresse. Wir haben dir dazu eine E-Mail geschickt.",
+  "authActionResendConfirmation": "Bestätigungs-E-Mail erneut senden",
+  "authErrorRateLimited": "Zu viele Versuche. Bitte warte einige Minuten und versuche es erneut.",
+  "authErrorWeakPasswordLength": "Das Passwort ist zu kurz.",
+  "authErrorWeakPasswordCharacters": "Das Passwort ist zu einfach. Wähle ein anderes.",
+  "authErrorWeakPasswordPwned": "Dieses Passwort ist sehr verbreitet und leicht zu erraten. Wähle ein anderes.",
+  "authErrorSamePassword": "Wähle ein anderes als dein bisheriges Passwort.",
+  "authErrorLinkInvalidOrExpired": "Der Link ist abgelaufen oder wurde schon benutzt.",
+  "authActionRequestNewLink": "Neuen Link anfordern",
+  "authErrorEmailInvalid": "Gib eine gültige E-Mail-Adresse ein.",
+  "authErrorRegistrationRejected": "Registrierung nicht möglich. Bitte prüfe deine Angaben.",
+  "authErrorNetwork": "Keine Verbindung. Für diesen Schritt brauchst du Internet.",
+  "authErrorUnexpected": "Etwas ist schiefgelaufen. Bitte versuche es erneut.",
+  "authActionRetry": "Erneut versuchen",
+  "authPasswordTooShort": "Mindestens 10 Zeichen – es fehlen noch {missing}.",
+  "authPasswordCommon": "Dieses Passwort ist sehr verbreitet und leicht zu erraten. Wähle ein anderes.",
+  "authPasswordRule": "Mindestens 10 Zeichen. Kein sehr verbreitetes Passwort.",
+  "authPasswordRequired": "Gib ein Passwort ein.",
+  "authDisplayNameEmpty": "Gib einen Anzeigenamen ein.",
+  "authDisplayNameTooLong": "Der Anzeigename darf höchstens {max} Zeichen lang sein.",
+  "authDisplayNameInvalid": "Dieser Anzeigename ist nicht erlaubt. Verwende sichtbare Zeichen.",
+  "authDisplayNameCounter": "{count}/{max}",
+  "authAgeNotConfirmed": "Shuffle ist erst ab 16 Jahren nutzbar.",
+  "authTermsNotAccepted": "Bitte stimme Datenschutzerklärung und Nutzungsbedingungen zu.",
+  "authFieldEmailLabel": "E-Mail-Adresse",
+  "authFieldPasswordLabel": "Passwort",
+  "authFieldDisplayNameLabel": "Anzeigename",
+  "authPasswordShow": "Passwort anzeigen",
+  "authPasswordHide": "Passwort verbergen",
+  "authCheckboxAgeLabel": "Ich bin mindestens 16 Jahre alt",
+  "authCheckboxTermsPrefix": "Ich habe die",
+  "authCheckboxTermsPrivacyLink": "Datenschutzerklärung",
+  "authCheckboxTermsMiddle": "gelesen und stimme den",
+  "authCheckboxTermsTermsLink": "Nutzungsbedingungen",
+  "authCheckboxTermsSuffix": "zu",
+  "authBannerTypeError": "Fehler",
+  "authBannerTypeInfo": "Hinweis",
+  "authSubmitting": "Bitte warten …",
+  "authRegisterTitle": "Konto erstellen",
+  "authRegisterSubmit": "Konto erstellen",
+  "authRegisterHaveAccount": "Schon ein Konto? Anmelden",
+  "authCheckEmailTitle": "Prüfe dein Postfach",
+  "authCheckEmailBody": "Wir haben dir eine E-Mail geschickt, falls die Adresse noch nicht registriert ist. Folge dem Link darin, um fortzufahren.",
+  "authCheckEmailDelayHint": "Die E-Mail kann einige Minuten dauern. Schau auch im Spam-Ordner nach.",
+  "authCheckEmailValidity": "Der Link ist {duration} gültig.",
+  "authCheckEmailValidityOneHour": "1 Stunde",
+  "authCheckEmailResend": "E-Mail erneut senden",
+  "authCheckEmailResent": "Wir haben die E-Mail erneut gesendet, falls es zu dieser Adresse etwas zu senden gibt.",
+  "authBackToLogin": "Zurück zur Anmeldung",
+  "authConfirmTitle": "E-Mail-Adresse bestätigen",
+  "authConfirmBody": "Ein Klick genügt, um deine E-Mail-Adresse zu bestätigen.",
+  "authConfirmSubmit": "E-Mail-Adresse bestätigen",
+  "authConfirmSuccess": "E-Mail bestätigt.",
+  "authConfirmSuccessMobileWeb": "Du kannst dich jetzt auch in der App anmelden.",
+  "authConfirmContinue": "Weiter",
+  "authRecoveryTitle": "Neues Passwort festlegen",
+  "authRecoveryBody": "Ein Klick genügt, um ein neues Passwort festzulegen.",
+  "authRecoverySubmit": "Weiter zum neuen Passwort"
 }

app/lib/l10n/app_en.arb

@@ -19,5 +19,95 @@
   "notFoundBackHome": "Back to start",
   "@notFoundBackHome": {
     "description": "Button on the 404 page that navigates to the start page"
-  }
+  },
+  "authErrorInvalidCredentials": "Email address or password is incorrect.",
+  "authErrorEmailNotConfirmed": "Please confirm your email address first. We sent you an email for this.",
+  "authActionResendConfirmation": "Resend confirmation email",
+  "authErrorRateLimited": "Too many attempts. Please wait a few minutes and try again.",
+  "authErrorWeakPasswordLength": "The password is too short.",
+  "authErrorWeakPasswordCharacters": "The password is too simple. Choose a different one.",
+  "authErrorWeakPasswordPwned": "This password is very common and easy to guess. Choose a different one.",
+  "authErrorSamePassword": "Choose a password different from your current one.",
+  "authErrorLinkInvalidOrExpired": "The link has expired or has already been used.",
+  "authActionRequestNewLink": "Request a new link",
+  "authErrorEmailInvalid": "Enter a valid email address.",
+  "authErrorRegistrationRejected": "Registration is not possible. Please check your details.",
+  "authErrorNetwork": "No connection. You need internet access for this step.",
+  "authErrorUnexpected": "Something went wrong. Please try again.",
+  "authActionRetry": "Try again",
+  "authPasswordTooShort": "At least 10 characters – {missing} more needed.",
+  "@authPasswordTooShort": {
+    "placeholders": {
+      "missing": {
+        "type": "int"
+      }
+    }
+  },
+  "authPasswordCommon": "This password is very common and easy to guess. Choose a different one.",
+  "authPasswordRule": "At least 10 characters. Not a very common password.",
+  "authPasswordRequired": "Enter a password.",
+  "authDisplayNameEmpty": "Enter a display name.",
+  "authDisplayNameTooLong": "The display name can be at most {max} characters long.",
+  "@authDisplayNameTooLong": {
+    "placeholders": {
+      "max": {
+        "type": "int"
+      }
+    }
+  },
+  "authDisplayNameInvalid": "This display name is not allowed. Use visible characters.",
+  "authDisplayNameCounter": "{count}/{max}",
+  "@authDisplayNameCounter": {
+    "placeholders": {
+      "count": {
+        "type": "int"
+      },
+      "max": {
+        "type": "int"
+      }
+    }
+  },
+  "authAgeNotConfirmed": "Shuffle can only be used from age 16.",
+  "authTermsNotAccepted": "Please agree to the privacy policy and the terms of use.",
+  "authFieldEmailLabel": "Email address",
+  "authFieldPasswordLabel": "Password",
+  "authFieldDisplayNameLabel": "Display name",
+  "authPasswordShow": "Show password",
+  "authPasswordHide": "Hide password",
+  "authCheckboxAgeLabel": "I am at least 16 years old",
+  "authCheckboxTermsPrefix": "I have read the",
+  "authCheckboxTermsPrivacyLink": "privacy policy",
+  "authCheckboxTermsMiddle": "and agree to the",
+  "authCheckboxTermsTermsLink": "terms of use",
+  "authCheckboxTermsSuffix": "",
+  "authBannerTypeError": "Error",
+  "authBannerTypeInfo": "Note",
+  "authSubmitting": "Please wait …",
+  "authRegisterTitle": "Create account",
+  "authRegisterSubmit": "Create account",
+  "authRegisterHaveAccount": "Already have an account? Sign in",
+  "authCheckEmailTitle": "Check your inbox",
+  "authCheckEmailBody": "We sent you an email if the address is not registered yet. Follow the link in it to continue.",
+  "authCheckEmailDelayHint": "The email can take a few minutes. Also check your spam folder.",
+  "authCheckEmailValidity": "The link is valid for {duration}.",
+  "@authCheckEmailValidity": {
+    "placeholders": {
+      "duration": {
+        "type": "String"
+      }
+    }
+  },
+  "authCheckEmailValidityOneHour": "1 hour",
+  "authCheckEmailResend": "Resend email",
+  "authCheckEmailResent": "We resent the email, if there is something to send for this address.",
+  "authBackToLogin": "Back to sign in",
+  "authConfirmTitle": "Confirm email address",
+  "authConfirmBody": "One click is enough to confirm your email address.",
+  "authConfirmSubmit": "Confirm email address",
+  "authConfirmSuccess": "Email confirmed.",
+  "authConfirmSuccessMobileWeb": "You can now also sign in in the app.",
+  "authConfirmContinue": "Continue",
+  "authRecoveryTitle": "Set a new password",
+  "authRecoveryBody": "One click is enough to set a new password.",
+  "authRecoverySubmit": "Continue to new password"
 }

app/lib/l10n/app_localizations.dart

@@ -127,6 +127,360 @@ abstract class AppLocalizations {
   /// In en, this message translates to:
   /// **'Back to start'**
   String get notFoundBackHome;
+
+  /// No description provided for @authErrorInvalidCredentials.
+  ///
+  /// In en, this message translates to:
+  /// **'Email address or password is incorrect.'**
+  String get authErrorInvalidCredentials;
+
+  /// No description provided for @authErrorEmailNotConfirmed.
+  ///
+  /// In en, this message translates to:
+  /// **'Please confirm your email address first. We sent you an email for this.'**
+  String get authErrorEmailNotConfirmed;
+
+  /// No description provided for @authActionResendConfirmation.
+  ///
+  /// In en, this message translates to:
+  /// **'Resend confirmation email'**
+  String get authActionResendConfirmation;
+
+  /// No description provided for @authErrorRateLimited.
+  ///
+  /// In en, this message translates to:
+  /// **'Too many attempts. Please wait a few minutes and try again.'**
+  String get authErrorRateLimited;
+
+  /// No description provided for @authErrorWeakPasswordLength.
+  ///
+  /// In en, this message translates to:
+  /// **'The password is too short.'**
+  String get authErrorWeakPasswordLength;
+
+  /// No description provided for @authErrorWeakPasswordCharacters.
+  ///
+  /// In en, this message translates to:
+  /// **'The password is too simple. Choose a different one.'**
+  String get authErrorWeakPasswordCharacters;
+
+  /// No description provided for @authErrorWeakPasswordPwned.
+  ///
+  /// In en, this message translates to:
+  /// **'This password is very common and easy to guess. Choose a different one.'**
+  String get authErrorWeakPasswordPwned;
+
+  /// No description provided for @authErrorSamePassword.
+  ///
+  /// In en, this message translates to:
+  /// **'Choose a password different from your current one.'**
+  String get authErrorSamePassword;
+
+  /// No description provided for @authErrorLinkInvalidOrExpired.
+  ///
+  /// In en, this message translates to:
+  /// **'The link has expired or has already been used.'**
+  String get authErrorLinkInvalidOrExpired;
+
+  /// No description provided for @authActionRequestNewLink.
+  ///
+  /// In en, this message translates to:
+  /// **'Request a new link'**
+  String get authActionRequestNewLink;
+
+  /// No description provided for @authErrorEmailInvalid.
+  ///
+  /// In en, this message translates to:
+  /// **'Enter a valid email address.'**
+  String get authErrorEmailInvalid;
+
+  /// No description provided for @authErrorRegistrationRejected.
+  ///
+  /// In en, this message translates to:
+  /// **'Registration is not possible. Please check your details.'**
+  String get authErrorRegistrationRejected;
+
+  /// No description provided for @authErrorNetwork.
+  ///
+  /// In en, this message translates to:
+  /// **'No connection. You need internet access for this step.'**
+  String get authErrorNetwork;
+
+  /// No description provided for @authErrorUnexpected.
+  ///
+  /// In en, this message translates to:
+  /// **'Something went wrong. Please try again.'**
+  String get authErrorUnexpected;
+
+  /// No description provided for @authActionRetry.
+  ///
+  /// In en, this message translates to:
+  /// **'Try again'**
+  String get authActionRetry;
+
+  /// No description provided for @authPasswordTooShort.
+  ///
+  /// In en, this message translates to:
+  /// **'At least 10 characters – {missing} more needed.'**
+  String authPasswordTooShort(int missing);
+
+  /// No description provided for @authPasswordCommon.
+  ///
+  /// In en, this message translates to:
+  /// **'This password is very common and easy to guess. Choose a different one.'**
+  String get authPasswordCommon;
+
+  /// No description provided for @authPasswordRule.
+  ///
+  /// In en, this message translates to:
+  /// **'At least 10 characters. Not a very common password.'**
+  String get authPasswordRule;
+
+  /// No description provided for @authPasswordRequired.
+  ///
+  /// In en, this message translates to:
+  /// **'Enter a password.'**
+  String get authPasswordRequired;
+
+  /// No description provided for @authDisplayNameEmpty.
+  ///
+  /// In en, this message translates to:
+  /// **'Enter a display name.'**
+  String get authDisplayNameEmpty;
+
+  /// No description provided for @authDisplayNameTooLong.
+  ///
+  /// In en, this message translates to:
+  /// **'The display name can be at most {max} characters long.'**
+  String authDisplayNameTooLong(int max);
+
+  /// No description provided for @authDisplayNameInvalid.
+  ///
+  /// In en, this message translates to:
+  /// **'This display name is not allowed. Use visible characters.'**
+  String get authDisplayNameInvalid;
+
+  /// No description provided for @authDisplayNameCounter.
+  ///
+  /// In en, this message translates to:
+  /// **'{count}/{max}'**
+  String authDisplayNameCounter(int count, int max);
+
+  /// No description provided for @authAgeNotConfirmed.
+  ///
+  /// In en, this message translates to:
+  /// **'Shuffle can only be used from age 16.'**
+  String get authAgeNotConfirmed;
+
+  /// No description provided for @authTermsNotAccepted.
+  ///
+  /// In en, this message translates to:
+  /// **'Please agree to the privacy policy and the terms of use.'**
+  String get authTermsNotAccepted;
+
+  /// No description provided for @authFieldEmailLabel.
+  ///
+  /// In en, this message translates to:
+  /// **'Email address'**
+  String get authFieldEmailLabel;
+
+  /// No description provided for @authFieldPasswordLabel.
+  ///
+  /// In en, this message translates to:
+  /// **'Password'**
+  String get authFieldPasswordLabel;
+
+  /// No description provided for @authFieldDisplayNameLabel.
+  ///
+  /// In en, this message translates to:
+  /// **'Display name'**
+  String get authFieldDisplayNameLabel;
+
+  /// No description provided for @authPasswordShow.
+  ///
+  /// In en, this message translates to:
+  /// **'Show password'**
+  String get authPasswordShow;
+
+  /// No description provided for @authPasswordHide.
+  ///
+  /// In en, this message translates to:
+  /// **'Hide password'**
+  String get authPasswordHide;
+
+  /// No description provided for @authCheckboxAgeLabel.
+  ///
+  /// In en, this message translates to:
+  /// **'I am at least 16 years old'**
+  String get authCheckboxAgeLabel;
+
+  /// No description provided for @authCheckboxTermsPrefix.
+  ///
+  /// In en, this message translates to:
+  /// **'I have read the'**
+  String get authCheckboxTermsPrefix;
+
+  /// No description provided for @authCheckboxTermsPrivacyLink.
+  ///
+  /// In en, this message translates to:
+  /// **'privacy policy'**
+  String get authCheckboxTermsPrivacyLink;
+
+  /// No description provided for @authCheckboxTermsMiddle.
+  ///
+  /// In en, this message translates to:
+  /// **'and agree to the'**
+  String get authCheckboxTermsMiddle;
+
+  /// No description provided for @authCheckboxTermsTermsLink.
+  ///
+  /// In en, this message translates to:
+  /// **'terms of use'**
+  String get authCheckboxTermsTermsLink;
+
+  /// No description provided for @authCheckboxTermsSuffix.
+  ///
+  /// In en, this message translates to:
+  /// **''**
+  String get authCheckboxTermsSuffix;
+
+  /// No description provided for @authBannerTypeError.
+  ///
+  /// In en, this message translates to:
+  /// **'Error'**
+  String get authBannerTypeError;
+
+  /// No description provided for @authBannerTypeInfo.
+  ///
+  /// In en, this message translates to:
+  /// **'Note'**
+  String get authBannerTypeInfo;
+
+  /// No description provided for @authSubmitting.
+  ///
+  /// In en, this message translates to:
+  /// **'Please wait …'**
+  String get authSubmitting;
+
+  /// No description provided for @authRegisterTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'Create account'**
+  String get authRegisterTitle;
+
+  /// No description provided for @authRegisterSubmit.
+  ///
+  /// In en, this message translates to:
+  /// **'Create account'**
+  String get authRegisterSubmit;
+
+  /// No description provided for @authRegisterHaveAccount.
+  ///
+  /// In en, this message translates to:
+  /// **'Already have an account? Sign in'**
+  String get authRegisterHaveAccount;
+
+  /// No description provided for @authCheckEmailTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'Check your inbox'**
+  String get authCheckEmailTitle;
+
+  /// No description provided for @authCheckEmailBody.
+  ///
+  /// In en, this message translates to:
+  /// **'We sent you an email if the address is not registered yet. Follow the link in it to continue.'**
+  String get authCheckEmailBody;
+
+  /// No description provided for @authCheckEmailDelayHint.
+  ///
+  /// In en, this message translates to:
+  /// **'The email can take a few minutes. Also check your spam folder.'**
+  String get authCheckEmailDelayHint;
+
+  /// No description provided for @authCheckEmailValidity.
+  ///
+  /// In en, this message translates to:
+  /// **'The link is valid for {duration}.'**
+  String authCheckEmailValidity(String duration);
+
+  /// No description provided for @authCheckEmailValidityOneHour.
+  ///
+  /// In en, this message translates to:
+  /// **'1 hour'**
+  String get authCheckEmailValidityOneHour;
+
+  /// No description provided for @authCheckEmailResend.
+  ///
+  /// In en, this message translates to:
+  /// **'Resend email'**
+  String get authCheckEmailResend;
+
+  /// No description provided for @authCheckEmailResent.
+  ///
+  /// In en, this message translates to:
+  /// **'We resent the email, if there is something to send for this address.'**
+  String get authCheckEmailResent;
+
+  /// No description provided for @authBackToLogin.
+  ///
+  /// In en, this message translates to:
+  /// **'Back to sign in'**
+  String get authBackToLogin;
+
+  /// No description provided for @authConfirmTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'Confirm email address'**
+  String get authConfirmTitle;
+
+  /// No description provided for @authConfirmBody.
+  ///
+  /// In en, this message translates to:
+  /// **'One click is enough to confirm your email address.'**
+  String get authConfirmBody;
+
+  /// No description provided for @authConfirmSubmit.
+  ///
+  /// In en, this message translates to:
+  /// **'Confirm email address'**
+  String get authConfirmSubmit;
+
+  /// No description provided for @authConfirmSuccess.
+  ///
+  /// In en, this message translates to:
+  /// **'Email confirmed.'**
+  String get authConfirmSuccess;
+
+  /// No description provided for @authConfirmSuccessMobileWeb.
+  ///
+  /// In en, this message translates to:
+  /// **'You can now also sign in in the app.'**
+  String get authConfirmSuccessMobileWeb;
+
+  /// No description provided for @authConfirmContinue.
+  ///
+  /// In en, this message translates to:
+  /// **'Continue'**
+  String get authConfirmContinue;
+
+  /// No description provided for @authRecoveryTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'Set a new password'**
+  String get authRecoveryTitle;
+
+  /// No description provided for @authRecoveryBody.
+  ///
+  /// In en, this message translates to:
+  /// **'One click is enough to set a new password.'**
+  String get authRecoveryBody;
+
+  /// No description provided for @authRecoverySubmit.
+  ///
+  /// In en, this message translates to:
+  /// **'Continue to new password'**
+  String get authRecoverySubmit;
 }
 
 class _AppLocalizationsDelegate

app/lib/l10n/app_localizations_de.dart

@@ -25,4 +25,210 @@ class AppLocalizationsDe extends AppLocalizations {
 
   @override
   String get notFoundBackHome => 'Zurück zum Start';
+
+  @override
+  String get authErrorInvalidCredentials =>
+      'E-Mail-Adresse oder Passwort ist nicht korrekt.';
+
+  @override
+  String get authErrorEmailNotConfirmed =>
+      'Bestätige zuerst deine E-Mail-Adresse. Wir haben dir dazu eine E-Mail geschickt.';
+
+  @override
+  String get authActionResendConfirmation =>
+      'Bestätigungs-E-Mail erneut senden';
+
+  @override
+  String get authErrorRateLimited =>
+      'Zu viele Versuche. Bitte warte einige Minuten und versuche es erneut.';
+
+  @override
+  String get authErrorWeakPasswordLength => 'Das Passwort ist zu kurz.';
+
+  @override
+  String get authErrorWeakPasswordCharacters =>
+      'Das Passwort ist zu einfach. Wähle ein anderes.';
+
+  @override
+  String get authErrorWeakPasswordPwned =>
+      'Dieses Passwort ist sehr verbreitet und leicht zu erraten. Wähle ein anderes.';
+
+  @override
+  String get authErrorSamePassword =>
+      'Wähle ein anderes als dein bisheriges Passwort.';
+
+  @override
+  String get authErrorLinkInvalidOrExpired =>
+      'Der Link ist abgelaufen oder wurde schon benutzt.';
+
+  @override
+  String get authActionRequestNewLink => 'Neuen Link anfordern';
+
+  @override
+  String get authErrorEmailInvalid => 'Gib eine gültige E-Mail-Adresse ein.';
+
+  @override
+  String get authErrorRegistrationRejected =>
+      'Registrierung nicht möglich. Bitte prüfe deine Angaben.';
+
+  @override
+  String get authErrorNetwork =>
+      'Keine Verbindung. Für diesen Schritt brauchst du Internet.';
+
+  @override
+  String get authErrorUnexpected =>
+      'Etwas ist schiefgelaufen. Bitte versuche es erneut.';
+
+  @override
+  String get authActionRetry => 'Erneut versuchen';
+
+  @override
+  String authPasswordTooShort(int missing) {
+    return 'Mindestens 10 Zeichen – es fehlen noch $missing.';
+  }
+
+  @override
+  String get authPasswordCommon =>
+      'Dieses Passwort ist sehr verbreitet und leicht zu erraten. Wähle ein anderes.';
+
+  @override
+  String get authPasswordRule =>
+      'Mindestens 10 Zeichen. Kein sehr verbreitetes Passwort.';
+
+  @override
+  String get authPasswordRequired => 'Gib ein Passwort ein.';
+
+  @override
+  String get authDisplayNameEmpty => 'Gib einen Anzeigenamen ein.';
+
+  @override
+  String authDisplayNameTooLong(int max) {
+    return 'Der Anzeigename darf höchstens $max Zeichen lang sein.';
+  }
+
+  @override
+  String get authDisplayNameInvalid =>
+      'Dieser Anzeigename ist nicht erlaubt. Verwende sichtbare Zeichen.';
+
+  @override
+  String authDisplayNameCounter(int count, int max) {
+    return '$count/$max';
+  }
+
+  @override
+  String get authAgeNotConfirmed => 'Shuffle ist erst ab 16 Jahren nutzbar.';
+
+  @override
+  String get authTermsNotAccepted =>
+      'Bitte stimme Datenschutzerklärung und Nutzungsbedingungen zu.';
+
+  @override
+  String get authFieldEmailLabel => 'E-Mail-Adresse';
+
+  @override
+  String get authFieldPasswordLabel => 'Passwort';
+
+  @override
+  String get authFieldDisplayNameLabel => 'Anzeigename';
+
+  @override
+  String get authPasswordShow => 'Passwort anzeigen';
+
+  @override
+  String get authPasswordHide => 'Passwort verbergen';
+
+  @override
+  String get authCheckboxAgeLabel => 'Ich bin mindestens 16 Jahre alt';
+
+  @override
+  String get authCheckboxTermsPrefix => 'Ich habe die';
+
+  @override
+  String get authCheckboxTermsPrivacyLink => 'Datenschutzerklärung';
+
+  @override
+  String get authCheckboxTermsMiddle => 'gelesen und stimme den';
+
+  @override
+  String get authCheckboxTermsTermsLink => 'Nutzungsbedingungen';
+
+  @override
+  String get authCheckboxTermsSuffix => 'zu';
+
+  @override
+  String get authBannerTypeError => 'Fehler';
+
+  @override
+  String get authBannerTypeInfo => 'Hinweis';
+
+  @override
+  String get authSubmitting => 'Bitte warten …';
+
+  @override
+  String get authRegisterTitle => 'Konto erstellen';
+
+  @override
+  String get authRegisterSubmit => 'Konto erstellen';
+
+  @override
+  String get authRegisterHaveAccount => 'Schon ein Konto? Anmelden';
+
+  @override
+  String get authCheckEmailTitle => 'Prüfe dein Postfach';
+
+  @override
+  String get authCheckEmailBody =>
+      'Wir haben dir eine E-Mail geschickt, falls die Adresse noch nicht registriert ist. Folge dem Link darin, um fortzufahren.';
+
+  @override
+  String get authCheckEmailDelayHint =>
+      'Die E-Mail kann einige Minuten dauern. Schau auch im Spam-Ordner nach.';
+
+  @override
+  String authCheckEmailValidity(String duration) {
+    return 'Der Link ist $duration gültig.';
+  }
+
+  @override
+  String get authCheckEmailValidityOneHour => '1 Stunde';
+
+  @override
+  String get authCheckEmailResend => 'E-Mail erneut senden';
+
+  @override
+  String get authCheckEmailResent =>
+      'Wir haben die E-Mail erneut gesendet, falls es zu dieser Adresse etwas zu senden gibt.';
+
+  @override
+  String get authBackToLogin => 'Zurück zur Anmeldung';
+
+  @override
+  String get authConfirmTitle => 'E-Mail-Adresse bestätigen';
+
+  @override
+  String get authConfirmBody =>
+      'Ein Klick genügt, um deine E-Mail-Adresse zu bestätigen.';
+
+  @override
+  String get authConfirmSubmit => 'E-Mail-Adresse bestätigen';
+
+  @override
+  String get authConfirmSuccess => 'E-Mail bestätigt.';
+
+  @override
+  String get authConfirmSuccessMobileWeb =>
+      'Du kannst dich jetzt auch in der App anmelden.';
+
+  @override
+  String get authConfirmContinue => 'Weiter';
+
+  @override
+  String get authRecoveryTitle => 'Neues Passwort festlegen';
+
+  @override
+  String get authRecoveryBody =>
+      'Ein Klick genügt, um ein neues Passwort festzulegen.';
+
+  @override
+  String get authRecoverySubmit => 'Weiter zum neuen Passwort';
 }

app/lib/l10n/app_localizations_en.dart

@@ -24,4 +24,207 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get notFoundBackHome => 'Back to start';
+
+  @override
+  String get authErrorInvalidCredentials =>
+      'Email address or password is incorrect.';
+
+  @override
+  String get authErrorEmailNotConfirmed =>
+      'Please confirm your email address first. We sent you an email for this.';
+
+  @override
+  String get authActionResendConfirmation => 'Resend confirmation email';
+
+  @override
+  String get authErrorRateLimited =>
+      'Too many attempts. Please wait a few minutes and try again.';
+
+  @override
+  String get authErrorWeakPasswordLength => 'The password is too short.';
+
+  @override
+  String get authErrorWeakPasswordCharacters =>
+      'The password is too simple. Choose a different one.';
+
+  @override
+  String get authErrorWeakPasswordPwned =>
+      'This password is very common and easy to guess. Choose a different one.';
+
+  @override
+  String get authErrorSamePassword =>
+      'Choose a password different from your current one.';
+
+  @override
+  String get authErrorLinkInvalidOrExpired =>
+      'The link has expired or has already been used.';
+
+  @override
+  String get authActionRequestNewLink => 'Request a new link';
+
+  @override
+  String get authErrorEmailInvalid => 'Enter a valid email address.';
+
+  @override
+  String get authErrorRegistrationRejected =>
+      'Registration is not possible. Please check your details.';
+
+  @override
+  String get authErrorNetwork =>
+      'No connection. You need internet access for this step.';
+
+  @override
+  String get authErrorUnexpected => 'Something went wrong. Please try again.';
+
+  @override
+  String get authActionRetry => 'Try again';
+
+  @override
+  String authPasswordTooShort(int missing) {
+    return 'At least 10 characters – $missing more needed.';
+  }
+
+  @override
+  String get authPasswordCommon =>
+      'This password is very common and easy to guess. Choose a different one.';
+
+  @override
+  String get authPasswordRule =>
+      'At least 10 characters. Not a very common password.';
+
+  @override
+  String get authPasswordRequired => 'Enter a password.';
+
+  @override
+  String get authDisplayNameEmpty => 'Enter a display name.';
+
+  @override
+  String authDisplayNameTooLong(int max) {
+    return 'The display name can be at most $max characters long.';
+  }
+
+  @override
+  String get authDisplayNameInvalid =>
+      'This display name is not allowed. Use visible characters.';
+
+  @override
+  String authDisplayNameCounter(int count, int max) {
+    return '$count/$max';
+  }
+
+  @override
+  String get authAgeNotConfirmed => 'Shuffle can only be used from age 16.';
+
+  @override
+  String get authTermsNotAccepted =>
+      'Please agree to the privacy policy and the terms of use.';
+
+  @override
+  String get authFieldEmailLabel => 'Email address';
+
+  @override
+  String get authFieldPasswordLabel => 'Password';
+
+  @override
+  String get authFieldDisplayNameLabel => 'Display name';
+
+  @override
+  String get authPasswordShow => 'Show password';
+
+  @override
+  String get authPasswordHide => 'Hide password';
+
+  @override
+  String get authCheckboxAgeLabel => 'I am at least 16 years old';
+
+  @override
+  String get authCheckboxTermsPrefix => 'I have read the';
+
+  @override
+  String get authCheckboxTermsPrivacyLink => 'privacy policy';
+
+  @override
+  String get authCheckboxTermsMiddle => 'and agree to the';
+
+  @override
+  String get authCheckboxTermsTermsLink => 'terms of use';
+
+  @override
+  String get authCheckboxTermsSuffix => '';
+
+  @override
+  String get authBannerTypeError => 'Error';
+
+  @override
+  String get authBannerTypeInfo => 'Note';
+
+  @override
+  String get authSubmitting => 'Please wait …';
+
+  @override
+  String get authRegisterTitle => 'Create account';
+
+  @override
+  String get authRegisterSubmit => 'Create account';
+
+  @override
+  String get authRegisterHaveAccount => 'Already have an account? Sign in';
+
+  @override
+  String get authCheckEmailTitle => 'Check your inbox';
+
+  @override
+  String get authCheckEmailBody =>
+      'We sent you an email if the address is not registered yet. Follow the link in it to continue.';
+
+  @override
+  String get authCheckEmailDelayHint =>
+      'The email can take a few minutes. Also check your spam folder.';
+
+  @override
+  String authCheckEmailValidity(String duration) {
+    return 'The link is valid for $duration.';
+  }
+
+  @override
+  String get authCheckEmailValidityOneHour => '1 hour';
+
+  @override
+  String get authCheckEmailResend => 'Resend email';
+
+  @override
+  String get authCheckEmailResent =>
+      'We resent the email, if there is something to send for this address.';
+
+  @override
+  String get authBackToLogin => 'Back to sign in';
+
+  @override
+  String get authConfirmTitle => 'Confirm email address';
+
+  @override
+  String get authConfirmBody =>
+      'One click is enough to confirm your email address.';
+
+  @override
+  String get authConfirmSubmit => 'Confirm email address';
+
+  @override
+  String get authConfirmSuccess => 'Email confirmed.';
+
+  @override
+  String get authConfirmSuccessMobileWeb =>
+      'You can now also sign in in the app.';
+
+  @override
+  String get authConfirmContinue => 'Continue';
+
+  @override
+  String get authRecoveryTitle => 'Set a new password';
+
+  @override
+  String get authRecoveryBody => 'One click is enough to set a new password.';
+
+  @override
+  String get authRecoverySubmit => 'Continue to new password';
 }

app/pubspec.lock

@@ -851,7 +851,7 @@ packages:
     source: hosted
     version: "1.4.0"
   url_launcher:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: url_launcher
       sha256: e8cc955c97e06df9879140a1fe301f3d493f01b7c62dec7f46834be31d7e9fda

app/pubspec.yaml

@@ -23,6 +23,7 @@ dependencies:
   json_annotation: 4.12.0
   logging: 1.3.0
   intl: 0.20.3
+  url_launcher: 6.3.3
 
 dev_dependencies:
   flutter_test:

app/test/core/config/auth_config_test.dart

@@ -0,0 +1,10 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shuffle/core/config/auth_config.dart';
+
+void main() {
+  test('KTO-01 Kriterium 8, AUTH-CFG-07: link validity is 3600 s', () {
+    // The text "1 Stunde / 1 hour" (authCheckEmailValidityOneHour) is only
+    // correct as long as this holds.
+    expect(AuthConfig.linkValidity.inSeconds, 3600);
+  });
+}

app/test/core/widgets/app_text_field_test.dart

@@ -30,6 +30,20 @@ void main() {
       expect(find.byIcon(Icons.error_outline), findsOneWidget);
     });
 
+    testWidgets('counterText replaces the default counter', (tester) async {
+      await pumpWidgetUnderTest(
+        tester,
+        const AppTextField(
+          label: 'Name',
+          maxLength: 30,
+          showCounter: true,
+          counterText: '2/30',
+        ),
+      );
+      expect(find.text('2/30'), findsOneWidget);
+      expect(find.text('0/30'), findsNothing);
+    });
+
     testWidgets('exposes the label as semantics label of the text field', (
       tester,
     ) async {

app/test/features/auth/presentation/auth_router_test.dart

@@ -115,25 +115,24 @@ void main() {
       expect(currentPath(router), '/');
     });
 
-    testWidgets('placeholder routes of spec 5.3 exist', (tester) async {
-      final (container: _, :router) = await start(tester);
+    testWidgets(
+      'routes of spec 5.3 exist (01a: real screens, rest placeholders)',
+      (tester) async {
+        final (container: _, :router) = await start(tester);
 
-      for (final (path, key) in [
-        ('/login', 'login'),
-        ('/register', 'register'),
-        ('/register/check-email', 'check_email'),
-        ('/forgot-password', 'forgot_password'),
-        ('/auth/confirm?token_hash=x&type=email', 'auth_confirm'),
-      ]) {
-        router.go(path);
-        await tester.pumpAndSettle();
-        expect(
-          find.byKey(Key('auth_placeholder_$key')),
-          findsOneWidget,
-          reason: path,
-        );
-      }
-    });
+        for (final (path, key) in [
+          ('/login', 'auth_placeholder_login'),
+          ('/register', 'register_screen'),
+          ('/register/check-email', 'check_email_screen'),
+          ('/forgot-password', 'auth_placeholder_forgot_password'),
+          ('/auth/confirm?token_hash=x&type=email', 'email_link_screen'),
+        ]) {
+          router.go(path);
+          await tester.pumpAndSettle();
+          expect(find.byKey(Key(key)), findsOneWidget, reason: path);
+        }
+      },
+    );
   });
 
   group('KTO-01 Kriterium 8, 9: recovery guard and sign-out hook', () {

app/test/features/auth/presentation/auth_ui_support.dart

@@ -0,0 +1,126 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_riverpod/misc.dart' show Override;
+import 'package:flutter_riverpod/misc.dart' show ProviderListenable;
+import 'package:flutter_test/flutter_test.dart';
+import 'package:go_router/go_router.dart';
+import 'package:mocktail/mocktail.dart';
+import 'package:shuffle/core/l10n/app_locale.dart';
+import 'package:shuffle/core/platform/platform_info.dart';
+import 'package:shuffle/core/platform/url_opener.dart';
+import 'package:shuffle/core/result/result.dart';
+import 'package:shuffle/features/auth/domain/auth_failure.dart';
+import 'package:shuffle/features/auth/domain/auth_repository.dart';
+import 'package:shuffle/features/auth/domain/email_link_type.dart';
+import 'package:shuffle/features/auth/domain/registration_input.dart';
+import 'package:shuffle/features/auth/domain/validation/common_passwords.dart';
+import 'package:shuffle/features/auth/presentation/auth_routes.dart';
+import 'package:shuffle/features/auth/presentation/providers/auth_providers.dart';
+
+import '../../../helpers/fakes.dart';
+import '../../../helpers/pump_app.dart';
+
+class MockAuthRepository extends Mock implements AuthRepository {}
+
+class FakeRegistrationInput extends Fake implements RegistrationInput {}
+
+/// [AppLocale] with a fixed language (tests do not depend on the device).
+class FixedAppLocale extends AppLocale {
+  FixedAppLocale(this.locale);
+
+  final Locale locale;
+
+  @override
+  Locale build() => locale;
+}
+
+const commonTestPasswords = SetCommonPasswordList({'passwort1234'});
+
+void registerAuthFallbacks() {
+  registerFallbackValue(FakeRegistrationInput());
+  registerFallbackValue(EmailLinkType.confirmation);
+}
+
+Result<void, AuthFailure> ok() => const Result.success(null);
+
+Result<void, AuthFailure> failed(AuthFailure value) => Result.failure(value);
+
+/// Overrides for auth UI tests: repository mock, fixed language, common
+/// password list, URL opener and platform.
+List<Override> authUiOverrides(
+  MockAuthRepository repository, {
+  Locale locale = const Locale('de'),
+  UrlOpener? urlOpener,
+  bool mobileWeb = false,
+  Future<CommonPasswordList> Function()? commonPasswords,
+  List<Override> extra = const [],
+}) => testOverrides(
+  overrides: [
+    authRepositoryProvider.overrideWithValue(repository),
+    appLocaleProvider.overrideWith(() => FixedAppLocale(locale)),
+    commonPasswordListProvider.overrideWith(
+      (ref) => commonPasswords?.call() ?? Future.value(commonTestPasswords),
+    ),
+    urlOpenerProvider.overrideWithValue(urlOpener ?? (_) async => true),
+    isMobileWebProvider.overrideWithValue(mobileWeb),
+    ...extra,
+  ],
+);
+
+/// The text field inside an `AppTextField`/`AppPasswordField` with [key].
+Finder fieldOf(String key) =>
+    find.descendant(of: find.byKey(Key(key)), matching: find.byType(TextField));
+
+/// Keeps an auto-dispose provider alive during a controller test.
+void keepAlive(ProviderContainer container, ProviderListenable<Object?> p) {
+  container.listen(p, (_, _) {});
+}
+
+typedef AuthUiHandle = ({ProviderContainer container, GoRouter router});
+
+/// Pumps the real auth routes (register, check-email, confirm; the others are
+/// placeholders) at [location] on a phone-sized screen.
+Future<AuthUiHandle> pumpAuthRoute(
+  WidgetTester tester,
+  MockAuthRepository repository, {
+  String location = '/register',
+  Object? extra,
+  Locale locale = const Locale('de'),
+  ThemeMode themeMode = ThemeMode.light,
+  double? textScale,
+  Size size = const Size(400, 800),
+  UrlOpener? urlOpener,
+  bool mobileWeb = false,
+  bool settle = true,
+}) async {
+  tester.view.physicalSize = size;
+  tester.view.devicePixelRatio = 1;
+  addTearDown(tester.view.reset);
+  final router = GoRouter(
+    initialLocation: location,
+    initialExtra: extra,
+    routes: authRoutes,
+  );
+  addTearDown(router.dispose);
+  final container = await pumpApp(
+    tester,
+    router: router,
+    locale: locale,
+    themeMode: themeMode,
+    textScale: textScale,
+    settle: settle,
+    overrides: authUiOverrides(
+      repository,
+      locale: locale,
+      urlOpener: urlOpener,
+      mobileWeb: mobileWeb,
+    ),
+  );
+  return (container: container, router: router);
+}
+
+/// All texts currently visible (for comparing two screens exactly).
+List<String> visibleTexts(WidgetTester tester) => [
+  for (final text in tester.widgetList<Text>(find.byType(Text)))
+    if (text.data != null) text.data!,
+];

app/test/features/auth/presentation/check_email/check_email_screen_test.dart

@@ -0,0 +1,223 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:mocktail/mocktail.dart';
+import 'package:shuffle/core/result/result.dart';
+import 'package:shuffle/features/auth/domain/auth_failure.dart';
+import 'package:shuffle/l10n/app_localizations_de.dart';
+import 'package:shuffle/l10n/app_localizations_en.dart';
+
+import '../../../../helpers/router_helpers.dart';
+import '../auth_ui_support.dart';
+
+final _de = AppLocalizationsDe();
+final _en = AppLocalizationsEn();
+
+void main() {
+  late MockAuthRepository repository;
+
+  setUpAll(registerAuthFallbacks);
+
+  setUp(() {
+    repository = MockAuthRepository();
+    when(() => repository.resendConfirmation(any()))
+        .thenAnswer((_) async => ok());
+  });
+
+  Future<AuthUiHandle> open(
+    WidgetTester tester, {
+    Object? extra = 'anna@example.com',
+    Locale locale = const Locale('de'),
+    ThemeMode themeMode = ThemeMode.light,
+    double? textScale,
+    Size size = const Size(400, 800),
+  }) => pumpAuthRoute(
+    tester,
+    repository,
+    location: '/register/check-email',
+    extra: extra,
+    locale: locale,
+    themeMode: themeMode,
+    textScale: textScale,
+    size: size,
+  );
+
+  Future<void> tapResend(WidgetTester tester) async {
+    await tester.ensureVisible(find.byKey(const Key('check_email_resend')));
+    await tester.tap(find.byKey(const Key('check_email_resend')));
+    await tester.pumpAndSettle();
+  }
+
+  group('KTO-01 Kriterium 1, 4: neutral message', () {
+    testWidgets('shows body, validity and the delay hint always', (
+      tester,
+    ) async {
+      await open(tester);
+
+      expect(find.text(_de.authCheckEmailTitle), findsOneWidget);
+      expect(find.text(_de.authCheckEmailBody), findsOneWidget);
+      expect(find.text(_de.authCheckEmailValidity('1 Stunde')), findsOneWidget);
+      expect(find.text(_de.authCheckEmailDelayHint), findsOneWidget);
+      expect(find.byKey(const Key('check_email_email')), findsNothing);
+    });
+
+    testWidgets('the text does not contain the address', (tester) async {
+      await open(tester);
+      expect(find.textContaining('anna@example.com'), findsNothing);
+    });
+  });
+
+  group('KTO-01 Kriterium 6: resend', () {
+    testWidgets('sends to the known address and confirms', (tester) async {
+      await open(tester);
+
+      await tapResend(tester);
+
+      verify(() => repository.resendConfirmation('anna@example.com')).called(1);
+      expect(find.text(_de.authCheckEmailResent), findsOneWidget);
+    });
+
+    testWidgets('F12: emailSendLimited gives exactly the same feedback', (
+      tester,
+    ) async {
+      await open(tester);
+      await tapResend(tester);
+      final success = visibleTexts(tester);
+      await tester.pumpWidget(const SizedBox.shrink());
+      await tester.pumpAndSettle();
+
+      when(
+        () => repository.resendConfirmation(any()),
+      ).thenAnswer((_) async => failed(const AuthFailure.emailSendLimited()));
+      await open(tester);
+      await tapResend(tester);
+      final limited = visibleTexts(tester);
+
+      expect(limited, success);
+      expect(limited, isNot(contains(_de.authErrorRateLimited)));
+      expect(limited, contains(_de.authCheckEmailResent));
+    });
+
+    testWidgets('IP rate limit shows the rate-limit hint', (tester) async {
+      when(() => repository.resendConfirmation(any()))
+          .thenAnswer((_) async => failed(const AuthFailure.rateLimited()));
+      await open(tester);
+
+      await tapResend(tester);
+
+      expect(find.text(_de.authErrorRateLimited), findsOneWidget);
+      expect(find.text(_de.authCheckEmailResent), findsNothing);
+    });
+
+    testWidgets('offline shows the offline hint', (tester) async {
+      when(() => repository.resendConfirmation(any()))
+          .thenAnswer((_) async => failed(const AuthFailure.network()));
+      await open(tester);
+
+      await tapResend(tester);
+
+      expect(find.text(_de.authErrorNetwork), findsOneWidget);
+    });
+
+    testWidgets('the button is locked while sending (no double tap)', (
+      tester,
+    ) async {
+      final completer = Completer<Result<void, AuthFailure>>();
+      when(() => repository.resendConfirmation(any()))
+          .thenAnswer((_) => completer.future);
+      await open(tester);
+
+      await tester.tap(find.byKey(const Key('check_email_resend')));
+      await tester.pump();
+      await tester.tap(find.byKey(const Key('check_email_resend')));
+      await tester.pump();
+
+      expect(find.byType(CircularProgressIndicator), findsOneWidget);
+      verify(() => repository.resendConfirmation(any())).called(1);
+      completer.complete(ok());
+      await tester.pumpAndSettle();
+    });
+  });
+
+  group('KTO-01 Kriterium 6: address missing after a web reload', () {
+    testWidgets('asks for the address and validates it', (tester) async {
+      await open(tester, extra: null);
+
+      expect(find.byKey(const Key('check_email_email')), findsOneWidget);
+      await tapResend(tester);
+      expect(find.text(_de.authErrorEmailInvalid), findsOneWidget);
+      verifyNever(() => repository.resendConfirmation(any()));
+
+      await tester.enterText(
+        fieldOf('check_email_email'),
+        ' berta@example.com ',
+      );
+      await tester.pump();
+      expect(find.text(_de.authErrorEmailInvalid), findsNothing);
+      await tapResend(tester);
+
+      verify(() => repository.resendConfirmation('berta@example.com'))
+          .called(1);
+      expect(find.text(_de.authCheckEmailResent), findsOneWidget);
+    });
+
+    testWidgets('an extra of the wrong type counts as missing', (tester) async {
+      await open(tester, extra: 42);
+      expect(find.byKey(const Key('check_email_email')), findsOneWidget);
+    });
+  });
+
+  testWidgets('back to sign in leads to /login', (tester) async {
+    final (:container, :router) = await open(tester);
+
+    await tester.ensureVisible(
+      find.byKey(const Key('check_email_back_to_login')),
+    );
+    await tester.tap(find.byKey(const Key('check_email_back_to_login')));
+    await tester.pumpAndSettle();
+
+    expect(currentPath(router), '/login');
+  });
+
+  testWidgets('QUE-05 Kriterium 2: english texts', (tester) async {
+    await open(tester, locale: const Locale('en'));
+
+    expect(find.text(_en.authCheckEmailBody), findsOneWidget);
+    expect(find.text(_en.authCheckEmailValidity('1 hour')), findsOneWidget);
+    expect(find.text(_en.authCheckEmailDelayHint), findsOneWidget);
+    expect(find.text(_en.authCheckEmailResend), findsOneWidget);
+  });
+
+  group('QUE-06 Kriterien 1-4: accessibility', () {
+    for (final mode in [ThemeMode.light, ThemeMode.dark]) {
+      for (final withEmail in [true, false]) {
+        testWidgets('meets the guidelines ($mode, address known: $withEmail)', (
+          tester,
+        ) async {
+          final handle = tester.ensureSemantics();
+          await open(
+            tester,
+            themeMode: mode,
+            extra: withEmail ? 'anna@example.com' : null,
+          );
+          await tapResend(tester);
+
+          await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
+          await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
+          await expectLater(tester, meetsGuideline(textContrastGuideline));
+          handle.dispose();
+        });
+      }
+    }
+
+    testWidgets('text scale 2.0 on a small phone does not overflow', (
+      tester,
+    ) async {
+      await open(tester, extra: null, textScale: 2, size: const Size(320, 640));
+      await tapResend(tester);
+
+      expect(tester.takeException(), isNull);
+    });
+  });
+}

app/test/features/auth/presentation/check_email/resend_controller_test.dart

@@ -0,0 +1,122 @@
+import 'dart:async';
+
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:mocktail/mocktail.dart';
+import 'package:shuffle/core/result/result.dart';
+import 'package:shuffle/features/auth/domain/auth_failure.dart';
+import 'package:shuffle/features/auth/domain/resend_origin.dart';
+import 'package:shuffle/features/auth/domain/validation/email_format.dart';
+import 'package:shuffle/features/auth/presentation/check_email/resend_controller.dart';
+
+import '../auth_ui_support.dart';
+
+void main() {
+  late MockAuthRepository repository;
+  late ProviderContainer container;
+
+  setUpAll(registerAuthFallbacks);
+
+  setUp(() {
+    repository = MockAuthRepository();
+    container = ProviderContainer.test(overrides: authUiOverrides(repository));
+    keepAlive(container, resendControllerProvider);
+  });
+
+  ResendController notifier() =>
+      container.read(resendControllerProvider.notifier);
+  ResendState state() => container.read(resendControllerProvider);
+
+  void stub(Result<void, AuthFailure> result) =>
+      when(() => repository.resendConfirmation(any()))
+          .thenAnswer((_) async => result);
+
+  group('KTO-01 Kriterium 6: resend', () {
+    test('sends to the trimmed address and reports success', () async {
+      stub(ok());
+
+      await notifier().resend(' anna@example.com ', origin: ResendOrigin.login);
+
+      verify(() => repository.resendConfirmation('anna@example.com')).called(1);
+      expect(state().sent, isTrue);
+      expect(state().failure, isNull);
+    });
+
+    test('an invalid address is not sent', () async {
+      await notifier().resend('anna', origin: ResendOrigin.checkEmail);
+
+      verifyNever(() => repository.resendConfirmation(any()));
+      expect(state().emailError, EmailError.invalid);
+      notifier().clearEmailError();
+      expect(state().emailError, isNull);
+    });
+
+    test('the button is locked while a request runs', () async {
+      final completer = Completer<Result<void, AuthFailure>>();
+      when(() => repository.resendConfirmation(any()))
+          .thenAnswer((_) => completer.future);
+
+      final first = notifier().resend(
+        'anna@example.com',
+        origin: ResendOrigin.checkEmail,
+      );
+      await Future<void>.delayed(Duration.zero);
+      expect(state().isSending, isTrue);
+      await notifier().resend(
+        'anna@example.com',
+        origin: ResendOrigin.checkEmail,
+      );
+      completer.complete(ok());
+      await first;
+
+      verify(() => repository.resendConfirmation(any())).called(1);
+      expect(state().sent, isTrue);
+    });
+  });
+
+  group('KTO-01 Kriterium 4, 6 (F12): emailSendLimited', () {
+    test('from the check-email screen counts as sent', () async {
+      stub(failed(const AuthFailure.emailSendLimited()));
+
+      await notifier().resend(
+        'anna@example.com',
+        origin: ResendOrigin.checkEmail,
+      );
+
+      expect(state().sent, isTrue);
+      expect(state().failure, isNull);
+    });
+
+    test('from the login screen becomes the rate-limit failure', () async {
+      stub(failed(const AuthFailure.emailSendLimited()));
+
+      await notifier().resend('anna@example.com', origin: ResendOrigin.login);
+
+      expect(state().sent, isFalse);
+      expect(state().failure, const AuthFailure.rateLimited());
+    });
+
+    test('over_request_rate_limit is shown from both origins', () async {
+      stub(failed(const AuthFailure.rateLimited()));
+
+      await notifier().resend(
+        'anna@example.com',
+        origin: ResendOrigin.checkEmail,
+      );
+
+      expect(state().failure, const AuthFailure.rateLimited());
+    });
+
+    test('Zustände Kriterium 2: network failure is reported', () async {
+      stub(failed(const AuthFailure.network()));
+
+      await notifier().resend(
+        'anna@example.com',
+        origin: ResendOrigin.checkEmail,
+      );
+
+      expect(state().failure, const AuthFailure.network());
+      expect(state().isSending, isFalse);
+    });
+  });
+}

app/test/features/auth/presentation/email_link/email_link_controller_test.dart

@@ -0,0 +1,121 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:mocktail/mocktail.dart';
+import 'package:shuffle/features/auth/domain/auth_failure.dart';
+import 'package:shuffle/features/auth/domain/email_link_request.dart';
+import 'package:shuffle/features/auth/domain/email_link_type.dart';
+import 'package:shuffle/features/auth/presentation/email_link/email_link_controller.dart';
+
+import '../auth_ui_support.dart';
+
+void main() {
+  late MockAuthRepository repository;
+  late ProviderContainer container;
+
+  setUpAll(registerAuthFallbacks);
+
+  setUp(() {
+    repository = MockAuthRepository();
+    container = ProviderContainer.test(overrides: authUiOverrides(repository));
+  });
+
+  EmailLinkController start(String? token, String? type) {
+    final provider = emailLinkControllerProvider(token, type);
+    keepAlive(container, provider);
+    return container.read(provider.notifier);
+  }
+
+  EmailLinkState stateOf(String? token, String? type) =>
+      container.read(emailLinkControllerProvider(token, type));
+
+  group('KTO-01 Kriterium 8: parameters', () {
+    test('email and signup mean confirmation, recovery stays recovery', () {
+      expect(
+        EmailLinkRequest.tryParse('t', 'email')?.type,
+        EmailLinkType.confirmation,
+      );
+      expect(
+        EmailLinkRequest.tryParse('t', 'signup')?.type,
+        EmailLinkType.confirmation,
+      );
+      expect(
+        EmailLinkRequest.tryParse('t', 'recovery')?.type,
+        EmailLinkType.recovery,
+      );
+    });
+
+    test('missing token or unknown type give no request', () {
+      expect(EmailLinkRequest.tryParse(null, 'email'), isNull);
+      expect(EmailLinkRequest.tryParse('  ', 'email'), isNull);
+      expect(EmailLinkRequest.tryParse('t', null), isNull);
+      expect(EmailLinkRequest.tryParse('t', 'magiclink'), isNull);
+    });
+
+    test(
+      'invalid parameters start in the invalid state and never verify',
+      () async {
+        final controller = start(null, 'email');
+        expect(stateOf(null, 'email').phase, EmailLinkPhase.invalid);
+
+        await controller.confirm();
+
+        verifyNever(() => repository.verifyEmailLink(any(), any()));
+      },
+    );
+  });
+
+  group('KTO-01 Kriterium 1, 8: redeeming', () {
+    test('creating the controller does not redeem the link (E3)', () {
+      start('hash', 'email');
+
+      verifyNever(() => repository.verifyEmailLink(any(), any()));
+      expect(stateOf('hash', 'email').phase, EmailLinkPhase.ready);
+    });
+
+    test('confirm redeems once with token and type', () async {
+      when(() => repository.verifyEmailLink(any(), any()))
+          .thenAnswer((_) async => ok());
+      final controller = start('hash', 'signup');
+
+      await controller.confirm();
+      await controller.confirm();
+
+      verify(
+        () => repository.verifyEmailLink('hash', EmailLinkType.confirmation),
+      ).called(1);
+      expect(stateOf('hash', 'signup').phase, EmailLinkPhase.success);
+    });
+
+    test('an expired or used link ends in the invalid state', () async {
+      when(() => repository.verifyEmailLink(any(), any())).thenAnswer(
+        (_) async => failed(const AuthFailure.linkInvalidOrExpired()),
+      );
+      final controller = start('hash', 'email');
+
+      await controller.confirm();
+
+      expect(stateOf('hash', 'email').phase, EmailLinkPhase.invalid);
+    });
+
+    test(
+      'Zustände Kriterium 2: a network failure allows another try',
+      () async {
+        when(() => repository.verifyEmailLink(any(), any()))
+            .thenAnswer((_) async => failed(const AuthFailure.network()));
+        final controller = start('hash', 'email');
+
+        await controller.confirm();
+
+        final state = stateOf('hash', 'email');
+        expect(state.phase, EmailLinkPhase.ready);
+        expect(state.failure, const AuthFailure.network());
+
+        when(() => repository.verifyEmailLink(any(), any()))
+            .thenAnswer((_) async => ok());
+        await controller.confirm();
+        expect(stateOf('hash', 'email').phase, EmailLinkPhase.success);
+        expect(stateOf('hash', 'email').failure, isNull);
+      },
+    );
+  });
+}

app/test/features/auth/presentation/email_link/email_link_screen_test.dart

@@ -0,0 +1,243 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:mocktail/mocktail.dart';
+import 'package:shuffle/core/result/result.dart';
+import 'package:shuffle/features/auth/domain/auth_failure.dart';
+import 'package:shuffle/features/auth/domain/email_link_type.dart';
+import 'package:shuffle/l10n/app_localizations_de.dart';
+import 'package:shuffle/l10n/app_localizations_en.dart';
+
+import '../../../../helpers/router_helpers.dart';
+import '../auth_ui_support.dart';
+
+final _de = AppLocalizationsDe();
+final _en = AppLocalizationsEn();
+
+void main() {
+  late MockAuthRepository repository;
+
+  setUpAll(registerAuthFallbacks);
+
+  setUp(() {
+    repository = MockAuthRepository();
+    when(() => repository.verifyEmailLink(any(), any()))
+        .thenAnswer((_) async => ok());
+  });
+
+  Future<AuthUiHandle> open(
+    WidgetTester tester, {
+    String location = '/auth/confirm?token_hash=abc123&type=email',
+    Locale locale = const Locale('de'),
+    ThemeMode themeMode = ThemeMode.light,
+    double? textScale,
+    Size size = const Size(400, 800),
+    bool mobileWeb = false,
+  }) => pumpAuthRoute(
+    tester,
+    repository,
+    location: location,
+    locale: locale,
+    themeMode: themeMode,
+    textScale: textScale,
+    size: size,
+    mobileWeb: mobileWeb,
+  );
+
+  Future<void> tapSubmit(WidgetTester tester) async {
+    await tester.ensureVisible(find.byKey(const Key('email_link_submit')));
+    await tester.tap(find.byKey(const Key('email_link_submit')));
+    await tester.pumpAndSettle();
+  }
+
+  group('KTO-01 Kriterium 1, 8: nothing happens before the click (E3)', () {
+    testWidgets('opening the page does not redeem the link', (tester) async {
+      await open(tester);
+
+      // Title and button share the text "E-Mail-Adresse bestätigen".
+      expect(find.text(_de.authConfirmTitle), findsNWidgets(2));
+      expect(find.text(_de.authConfirmBody), findsOneWidget);
+      verifyNever(() => repository.verifyEmailLink(any(), any()));
+    });
+
+    testWidgets('type=signup is accepted as confirmation', (tester) async {
+      await open(
+        tester,
+        location: '/auth/confirm?token_hash=abc123&type=signup',
+      );
+
+      await tapSubmit(tester);
+
+      verify(
+        () => repository.verifyEmailLink('abc123', EmailLinkType.confirmation),
+      ).called(1);
+    });
+  });
+
+  group('KTO-01 Kriterium 1: confirmation', () {
+    testWidgets('the click redeems the link and shows the success', (
+      tester,
+    ) async {
+      await open(tester);
+
+      await tapSubmit(tester);
+
+      verify(
+        () => repository.verifyEmailLink('abc123', EmailLinkType.confirmation),
+      ).called(1);
+      expect(find.text(_de.authConfirmSuccess), findsOneWidget);
+      expect(find.text(_de.authConfirmSuccessMobileWeb), findsNothing);
+      expect(find.byKey(const Key('email_link_submit')), findsNothing);
+    });
+
+    testWidgets('mobile web adds the hint about the app', (tester) async {
+      await open(tester, mobileWeb: true);
+
+      await tapSubmit(tester);
+
+      expect(
+        find.text(
+          '${_de.authConfirmSuccess} ${_de.authConfirmSuccessMobileWeb}',
+        ),
+        findsOneWidget,
+      );
+    });
+
+    testWidgets('continue leads to the start page', (tester) async {
+      final (:container, :router) = await open(tester);
+      await tapSubmit(tester);
+
+      await tester.tap(find.byKey(const Key('email_link_continue')));
+      await tester.pumpAndSettle();
+
+      expect(currentPath(router), '/');
+    });
+
+    testWidgets('while redeeming the button is locked', (tester) async {
+      final completer = Completer<Result<void, AuthFailure>>();
+      when(() => repository.verifyEmailLink(any(), any()))
+          .thenAnswer((_) => completer.future);
+      await open(tester);
+
+      await tester.tap(find.byKey(const Key('email_link_submit')));
+      await tester.pump();
+      await tester.tap(find.byKey(const Key('email_link_submit')));
+      await tester.pump();
+
+      expect(find.byType(CircularProgressIndicator), findsOneWidget);
+      verify(() => repository.verifyEmailLink(any(), any())).called(1);
+      completer.complete(ok());
+      await tester.pumpAndSettle();
+    });
+  });
+
+  group('KTO-01 Kriterium 8: invalid links', () {
+    testWidgets('an expired or used link shows the error and a way out', (
+      tester,
+    ) async {
+      when(() => repository.verifyEmailLink(any(), any())).thenAnswer(
+        (_) async => failed(const AuthFailure.linkInvalidOrExpired()),
+      );
+      final (:container, :router) = await open(tester);
+
+      await tapSubmit(tester);
+
+      expect(find.text(_de.authErrorLinkInvalidOrExpired), findsOneWidget);
+      expect(find.byKey(const Key('email_link_submit')), findsNothing);
+
+      await tester.tap(find.text(_de.authActionRequestNewLink));
+      await tester.pumpAndSettle();
+      expect(currentPath(router), '/login');
+    });
+
+    for (final location in [
+      '/auth/confirm',
+      '/auth/confirm?type=email',
+      '/auth/confirm?token_hash=abc',
+      '/auth/confirm?token_hash=abc&type=magiclink',
+    ]) {
+      testWidgets('missing or unknown parameters: $location', (tester) async {
+        await open(tester, location: location);
+
+        expect(find.text(_de.authErrorLinkInvalidOrExpired), findsOneWidget);
+        expect(find.byKey(const Key('email_link_submit')), findsNothing);
+        verifyNever(() => repository.verifyEmailLink(any(), any()));
+      });
+    }
+
+    testWidgets('Zustände Kriterium 2: offline allows another try', (
+      tester,
+    ) async {
+      when(() => repository.verifyEmailLink(any(), any()))
+          .thenAnswer((_) async => failed(const AuthFailure.network()));
+      await open(tester);
+
+      await tapSubmit(tester);
+
+      expect(find.text(_de.authErrorNetwork), findsOneWidget);
+      expect(find.byKey(const Key('email_link_submit')), findsOneWidget);
+
+      when(() => repository.verifyEmailLink(any(), any()))
+          .thenAnswer((_) async => ok());
+      await tapSubmit(tester);
+      expect(find.text(_de.authConfirmSuccess), findsOneWidget);
+    });
+  });
+
+  testWidgets('recovery links show their own texts and redeem as recovery', (
+    tester,
+  ) async {
+    await open(
+      tester,
+      location: '/auth/confirm?token_hash=abc123&type=recovery',
+    );
+
+    expect(find.text(_de.authRecoveryTitle), findsOneWidget);
+    expect(find.text(_de.authRecoverySubmit), findsOneWidget);
+    await tapSubmit(tester);
+    verify(() => repository.verifyEmailLink('abc123', EmailLinkType.recovery))
+        .called(1);
+  });
+
+  testWidgets('QUE-05 Kriterium 2: english texts', (tester) async {
+    await open(tester, locale: const Locale('en'));
+
+    expect(find.text(_en.authConfirmTitle), findsNWidgets(2));
+    expect(find.text(_en.authConfirmBody), findsOneWidget);
+  });
+
+  group('QUE-06 Kriterien 1-4: accessibility', () {
+    for (final mode in [ThemeMode.light, ThemeMode.dark]) {
+      testWidgets('meets the guidelines ($mode)', (tester) async {
+        final handle = tester.ensureSemantics();
+        await open(tester, themeMode: mode);
+
+        await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
+        await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
+        await expectLater(tester, meetsGuideline(textContrastGuideline));
+
+        handle.dispose();
+      });
+    }
+
+    testWidgets('the error state meets the guidelines', (tester) async {
+      final handle = tester.ensureSemantics();
+      await open(tester, location: '/auth/confirm?token_hash=x&type=bad');
+
+      await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
+      await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
+      await expectLater(tester, meetsGuideline(textContrastGuideline));
+      handle.dispose();
+    });
+
+    testWidgets('text scale 2.0 on a small phone does not overflow', (
+      tester,
+    ) async {
+      await open(tester, textScale: 2, size: const Size(320, 640));
+      await tapSubmit(tester);
+
+      expect(tester.takeException(), isNull);
+    });
+  });
+}

app/test/features/auth/presentation/register/register_controller_test.dart

@@ -0,0 +1,408 @@
+import 'dart:async';
+
+import 'package:flutter/widgets.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:mocktail/mocktail.dart';
+import 'package:shuffle/core/result/result.dart';
+import 'package:shuffle/features/auth/domain/auth_failure.dart';
+import 'package:shuffle/features/auth/domain/registration_input.dart';
+import 'package:shuffle/features/auth/domain/validation/common_passwords.dart';
+import 'package:shuffle/features/auth/domain/validation/display_name_rule.dart';
+import 'package:shuffle/features/auth/domain/validation/email_format.dart';
+import 'package:shuffle/features/auth/domain/validation/password_policy.dart';
+import 'package:shuffle/features/auth/presentation/providers/auth_providers.dart';
+import 'package:shuffle/features/auth/presentation/register/register_controller.dart';
+import 'package:shuffle/features/auth/presentation/register/register_state.dart';
+
+import '../../../../helpers/fakes.dart';
+import '../auth_ui_support.dart';
+
+void main() {
+  late MockAuthRepository repository;
+  late List<Uri> opened;
+  late bool openResult;
+
+  setUpAll(registerAuthFallbacks);
+
+  setUp(() {
+    repository = MockAuthRepository();
+    opened = [];
+    openResult = true;
+    when(() => repository.signUp(any())).thenAnswer((_) async => ok());
+  });
+
+  ProviderContainer makeContainer({
+    Locale locale = const Locale('de'),
+    Future<CommonPasswordList> Function()? commonPasswords,
+  }) {
+    final container = ProviderContainer.test(
+      overrides: authUiOverrides(
+        repository,
+        locale: locale,
+        urlOpener: (uri) async {
+          opened.add(uri);
+          return openResult;
+        },
+        commonPasswords: commonPasswords,
+      ),
+    );
+    keepAlive(container, registerControllerProvider);
+    return container;
+  }
+
+  RegisterController notifier(ProviderContainer c) =>
+      c.read(registerControllerProvider.notifier);
+
+  RegisterState stateOf(ProviderContainer c) =>
+      c.read(registerControllerProvider);
+
+  void fillValid(
+    RegisterController controller, {
+    String email = ' anna@example.com ',
+    String password = 'geheim-und-lang',
+    String name = '  Anna  ',
+  }) {
+    controller
+      ..emailChanged(email)
+      ..passwordChanged(password)
+      ..displayNameChanged(name)
+      ..ageConfirmedChanged(value: true)
+      ..termsAcceptedChanged(value: true);
+  }
+
+  group('KTO-01 Kriterium 1: submit', () {
+    test('KTO-01 Kriterium 11 (Client): sends all data, terms version and locale to signUp', () async {
+      final container = makeContainer(locale: const Locale('en'));
+      fillValid(notifier(container));
+
+      final result = await notifier(container).submit();
+
+      expect(result, isTrue);
+      final input =
+          verify(() => repository.signUp(captureAny())).captured.single
+              as RegistrationInput;
+      expect(input.email, 'anna@example.com');
+      expect(input.password, 'geheim-und-lang');
+      expect(input.displayName, 'Anna');
+      expect(input.ageConfirmed, isTrue);
+      expect(input.termsAccepted, isTrue);
+      expect(input.termsVersion, testAppConfig().termsVersion);
+      expect(input.locale, 'en');
+      expect(stateOf(container).isSubmitting, isFalse);
+    });
+
+    test('KTO-01 Kriterium 11 (Client): mail language follows the active UI language', () async {
+      final container = makeContainer();
+      fillValid(notifier(container));
+
+      await notifier(container).submit();
+
+      final input =
+          verify(() => repository.signUp(captureAny())).captured.single
+              as RegistrationInput;
+      expect(input.locale, 'de');
+    });
+
+    test('ignores a second submit while one is running', () async {
+      final completer = Completer<Result<void, AuthFailure>>();
+      when(() => repository.signUp(any())).thenAnswer((_) => completer.future);
+      final container = makeContainer();
+      fillValid(notifier(container));
+
+      final first = notifier(container).submit();
+      await Future<void>.delayed(Duration.zero);
+      expect(stateOf(container).isSubmitting, isTrue);
+      expect(await notifier(container).submit(), isFalse);
+      completer.complete(ok());
+      expect(await first, isTrue);
+      verify(() => repository.signUp(any())).called(1);
+    });
+  });
+
+  group('KTO-01 Kriterium 2: minimum age', () {
+    test(
+      'without the age confirmation nothing is sent and the error shows',
+      () async {
+        final container = makeContainer();
+        fillValid(notifier(container));
+        notifier(container).ageConfirmedChanged(value: false);
+
+        expect(await notifier(container).submit(), isFalse);
+
+        verifyNever(() => repository.signUp(any()));
+        expect(stateOf(container).shownAgeError, isTrue);
+        expect(stateOf(container).focusField, RegisterField.ageConfirmation);
+      },
+    );
+
+    test('QUE-04 Kriterium 1: without consent nothing is sent', () async {
+      final container = makeContainer();
+      fillValid(notifier(container));
+      notifier(container).termsAcceptedChanged(value: false);
+
+      expect(await notifier(container).submit(), isFalse);
+
+      verifyNever(() => repository.signUp(any()));
+      expect(stateOf(container).shownTermsError, isTrue);
+    });
+
+    test('the error disappears when the box is ticked', () async {
+      final container = makeContainer();
+      await notifier(container).submit();
+      expect(stateOf(container).shownAgeError, isTrue);
+
+      notifier(container).ageConfirmedChanged(value: true);
+
+      expect(stateOf(container).shownAgeError, isFalse);
+    });
+  });
+
+  group('KTO-01 Kriterium 3: password', () {
+    test('is checked while typing: too short names the missing count', () {
+      final container = makeContainer();
+
+      notifier(container).passwordChanged('123456789');
+
+      expect(
+        stateOf(container).shownPasswordError,
+        const PasswordError.tooShort(1),
+      );
+    });
+
+    test('10 characters are enough', () {
+      final container = makeContainer();
+      notifier(container).passwordChanged('1234567890');
+      expect(stateOf(container).shownPasswordError, isNull);
+    });
+
+    test('a common password is rejected once the list is loaded', () async {
+      final container = makeContainer();
+
+      notifier(container).passwordChanged(' PassWort1234 ');
+      await notifier(container).loadCommonPasswords();
+
+      expect(stateOf(container).shownPasswordError, isA<PasswordCommon>());
+      expect(await notifier(container).submit(), isFalse);
+      verifyNever(() => repository.signUp(any()));
+    });
+
+    test('an empty password is shown as required after blur', () {
+      final container = makeContainer();
+      notifier(container).fieldBlurred(RegisterField.password);
+      expect(stateOf(container).shownPasswordRequired, isTrue);
+    });
+
+    test(
+      'weak_password from the server is mapped to the password field',
+      () async {
+        when(() => repository.signUp(any())).thenAnswer(
+          (_) async => failed(
+            const AuthFailure.weakPassword([WeakPasswordReason.length]),
+          ),
+        );
+        final container = makeContainer();
+        fillValid(notifier(container));
+
+        expect(await notifier(container).submit(), isFalse);
+
+        expect(stateOf(container).serverPasswordReasons, [
+          WeakPasswordReason.length,
+        ]);
+        expect(stateOf(container).bannerFailure, isNull);
+        expect(stateOf(container).focusField, RegisterField.password);
+
+        notifier(container).passwordChanged('anderes-passwort');
+        expect(stateOf(container).serverPasswordReasons, isNull);
+      },
+    );
+
+    test('Zustände Kriterium 3: if the list cannot be loaded, only the length rule runs', () async {
+      final container = makeContainer(
+        commonPasswords: () => Future.error(StateError('asset missing')),
+      );
+      fillValid(notifier(container), password: 'passwort1234');
+
+      expect(await notifier(container).submit(), isTrue);
+    });
+  });
+
+  group('KTO-01 Kriterium 4: no hint whether the account exists', () {
+    test('emailSendLimited counts as success (F12)', () async {
+      when(
+        () => repository.signUp(any()),
+      ).thenAnswer((_) async => failed(const AuthFailure.emailSendLimited()));
+      final container = makeContainer();
+      fillValid(notifier(container));
+
+      expect(await notifier(container).submit(), isTrue);
+      expect(stateOf(container).bannerFailure, isNull);
+    });
+
+    test('plain success leads to the same result', () async {
+      final container = makeContainer();
+      fillValid(notifier(container));
+
+      expect(await notifier(container).submit(), isTrue);
+      expect(stateOf(container).bannerFailure, isNull);
+    });
+
+    test('over_request_rate_limit stays a visible rate-limit banner', () async {
+      when(() => repository.signUp(any()))
+          .thenAnswer((_) async => failed(const AuthFailure.rateLimited()));
+      final container = makeContainer();
+      fillValid(notifier(container));
+
+      expect(await notifier(container).submit(), isFalse);
+      expect(stateOf(container).bannerFailure, const AuthFailure.rateLimited());
+    });
+  });
+
+  group('KTO-01 Kriterium 10: display name', () {
+    Future<DisplayNameError?> errorFor(String name) async {
+      final container = makeContainer();
+      notifier(container)
+        ..displayNameChanged(name)
+        ..fieldBlurred(RegisterField.displayName);
+      return stateOf(container).shownDisplayNameError;
+    }
+
+    test('empty and whitespace only are rejected', () async {
+      expect(await errorFor(''), DisplayNameError.empty);
+      expect(await errorFor('   '), DisplayNameError.empty);
+    });
+
+    test('30 code points are valid, 31 are too long', () async {
+      expect(await errorFor('a' * 30), isNull);
+      expect(await errorFor('a' * 31), DisplayNameError.tooLong);
+    });
+
+    test('counts code points, not UTF-16 units', () async {
+      expect(await errorFor('😀' * 30), isNull);
+      expect(await errorFor('😀' * 31), DisplayNameError.tooLong);
+    });
+
+    test('the counter uses the trimmed code point length', () {
+      final container = makeContainer();
+      notifier(container).displayNameChanged('  😀😀  ');
+      expect(stateOf(container).displayNameLength, 2);
+    });
+
+    test('U+200B anywhere is invalid', () async {
+      expect(await errorFor('A​B'), DisplayNameError.invalidCharacter);
+      expect(await errorFor('​'), DisplayNameError.invalidCharacter);
+    });
+
+    test('an invalid name blocks the submit', () async {
+      final container = makeContainer();
+      fillValid(notifier(container), name: '   ');
+
+      expect(await notifier(container).submit(), isFalse);
+
+      verifyNever(() => repository.signUp(any()));
+      expect(stateOf(container).focusField, RegisterField.displayName);
+    });
+  });
+
+  group('KTO-01 Kriterium 1: email', () {
+    test(
+      'an invalid address is shown after blur and blocks the submit',
+      () async {
+        final container = makeContainer();
+        notifier(container)
+          ..emailChanged('anna')
+          ..fieldBlurred(RegisterField.email);
+
+        expect(stateOf(container).shownEmailError, EmailError.invalid);
+        expect(await notifier(container).submit(), isFalse);
+      },
+    );
+
+    test('invalid email from the server goes to the email field', () async {
+      when(() => repository.signUp(any()))
+          .thenAnswer((_) async => failed(const AuthFailure.invalidEmail()));
+      final container = makeContainer();
+      fillValid(notifier(container));
+
+      await notifier(container).submit();
+
+      expect(stateOf(container).serverEmailInvalid, isTrue);
+      expect(stateOf(container).focusField, RegisterField.email);
+    });
+  });
+
+  group('Zustände Kriterium 2, 3: failures keep the input', () {
+    for (final failure in [
+      const AuthFailure.network(),
+      const AuthFailure.unexpected(),
+      const AuthFailure.registrationRejected(),
+    ]) {
+      test('${failure.runtimeType} becomes a banner', () async {
+        when(() => repository.signUp(any()))
+            .thenAnswer((_) async => failed(failure));
+        final container = makeContainer();
+        fillValid(notifier(container));
+
+        expect(await notifier(container).submit(), isFalse);
+
+        final state = stateOf(container);
+        expect(state.bannerFailure, failure);
+        expect(state.isSubmitting, isFalse);
+        expect(state.password, 'geheim-und-lang');
+        expect(state.displayName, '  Anna  ');
+        expect(state.ageConfirmed, isTrue);
+      });
+    }
+
+    test('a new attempt clears the banner', () async {
+      when(() => repository.signUp(any()))
+          .thenAnswer((_) async => failed(const AuthFailure.network()));
+      final container = makeContainer();
+      fillValid(notifier(container));
+      await notifier(container).submit();
+
+      when(() => repository.signUp(any())).thenAnswer((_) async => ok());
+      expect(await notifier(container).submit(), isTrue);
+      expect(stateOf(container).bannerFailure, isNull);
+    });
+  });
+
+  group('QUE-04 Kriterium 1: legal texts', () {
+    test('open the URLs from the app config', () async {
+      final container = makeContainer();
+
+      expect(
+        await notifier(container).openLegalDocument(LegalDocument.privacy),
+        isTrue,
+      );
+      await notifier(container).openLegalDocument(LegalDocument.terms);
+
+      expect(opened, [
+        Uri.parse(testAppConfig().legalPrivacyUrl),
+        Uri.parse(testAppConfig().legalTermsUrl),
+      ]);
+    });
+
+    test('report a failure to open', () async {
+      openResult = false;
+      final container = makeContainer();
+      expect(
+        await notifier(container).openLegalDocument(LegalDocument.terms),
+        isFalse,
+      );
+    });
+  });
+
+  test('factory provider reads terms version and locale', () {
+    final container = makeContainer();
+    final input = container.read(registrationInputFactoryProvider)(
+      email: 'a@b.de',
+      password: 'x',
+      displayName: 'n',
+      ageConfirmed: true,
+      termsAccepted: true,
+    );
+    expect(input.termsVersion, 'test-1');
+    expect(input.locale, 'de');
+  });
+}

app/test/features/auth/presentation/register/register_screen_test.dart

@@ -0,0 +1,480 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:mocktail/mocktail.dart';
+import 'package:shuffle/core/platform/url_opener.dart';
+import 'package:shuffle/core/result/result.dart';
+import 'package:shuffle/features/auth/domain/auth_failure.dart';
+import 'package:shuffle/features/auth/domain/registration_input.dart';
+import 'package:shuffle/l10n/app_localizations_de.dart';
+import 'package:shuffle/l10n/app_localizations_en.dart';
+
+import '../../../../helpers/fakes.dart';
+import '../../../../helpers/router_helpers.dart';
+import '../auth_ui_support.dart';
+
+final _de = AppLocalizationsDe();
+final _en = AppLocalizationsEn();
+
+void main() {
+  late MockAuthRepository repository;
+
+  setUpAll(registerAuthFallbacks);
+
+  setUp(() {
+    repository = MockAuthRepository();
+    when(() => repository.signUp(any())).thenAnswer((_) async => ok());
+  });
+
+  Future<AuthUiHandle> open(
+    WidgetTester tester, {
+    Locale locale = const Locale('de'),
+    ThemeMode themeMode = ThemeMode.light,
+    double? textScale,
+    Size size = const Size(400, 800),
+    UrlOpener? urlOpener,
+  }) => pumpAuthRoute(
+    tester,
+    repository,
+    locale: locale,
+    themeMode: themeMode,
+    textScale: textScale,
+    size: size,
+    urlOpener: urlOpener,
+  );
+
+  Future<void> type(WidgetTester tester, String key, String text) async {
+    await tester.ensureVisible(fieldOf(key));
+    await tester.enterText(fieldOf(key), text);
+    await tester.pump();
+  }
+
+  Future<void> tapKey(WidgetTester tester, String key) async {
+    final finder = find.byKey(Key(key));
+    await tester.ensureVisible(finder);
+    await tester.tap(finder);
+    await tester.pump();
+  }
+
+  Future<void> fillValid(WidgetTester tester) async {
+    await type(tester, 'register_email', 'anna@example.com');
+    await type(tester, 'register_password', 'geheim-und-lang');
+    await type(tester, 'register_display_name', 'Anna');
+    await tapKey(tester, 'register_age_checkbox');
+    await tapKey(tester, 'register_terms_checkbox');
+  }
+
+  Future<void> submit(WidgetTester tester) async {
+    await tapKey(tester, 'register_submit');
+    await tester.pumpAndSettle();
+  }
+
+  group('KTO-01 Kriterium 1: valid registration', () {
+    testWidgets('sends the data and shows the check-email page', (
+      tester,
+    ) async {
+      final (:container, :router) = await open(tester);
+
+      await fillValid(tester);
+      await submit(tester);
+
+      final input =
+          verify(() => repository.signUp(captureAny())).captured.single
+              as RegistrationInput;
+      expect(input.email, 'anna@example.com');
+      expect(input.displayName, 'Anna');
+      expect(input.locale, 'de');
+      expect(input.termsVersion, testAppConfig().termsVersion);
+      expect(currentPath(router), '/register/check-email');
+      expect(find.byKey(const Key('check_email_screen')), findsOneWidget);
+      expect(find.text(_de.authCheckEmailBody), findsOneWidget);
+    });
+
+    testWidgets('the enter key in the last field submits', (tester) async {
+      final (:container, :router) = await open(tester);
+      await fillValid(tester);
+
+      await tester.showKeyboard(fieldOf('register_display_name'));
+      await tester.testTextInput.receiveAction(TextInputAction.done);
+      await tester.pumpAndSettle();
+
+      verify(() => repository.signUp(any())).called(1);
+      expect(currentPath(router), '/register/check-email');
+    });
+
+    testWidgets('the fields carry autofill hints and keyboard types', (
+      tester,
+    ) async {
+      await open(tester);
+
+      final email = tester.widget<TextField>(fieldOf('register_email'));
+      expect(email.autofillHints, contains(AutofillHints.email));
+      expect(email.keyboardType, TextInputType.emailAddress);
+      expect(email.textInputAction, TextInputAction.next);
+      final password = tester.widget<TextField>(fieldOf('register_password'));
+      expect(password.autofillHints, contains(AutofillHints.newPassword));
+      expect(password.obscureText, isTrue);
+      final name = tester.widget<TextField>(fieldOf('register_display_name'));
+      expect(name.textInputAction, TextInputAction.done);
+    });
+  });
+
+  group('KTO-01 Kriterium 2: minimum age', () {
+    testWidgets(
+      'without the confirmation the reason shows and nothing is sent',
+      (tester) async {
+        await open(tester);
+        await type(tester, 'register_email', 'anna@example.com');
+        await type(tester, 'register_password', 'geheim-und-lang');
+        await type(tester, 'register_display_name', 'Anna');
+        await tapKey(tester, 'register_terms_checkbox');
+
+        await submit(tester);
+
+        expect(find.text(_de.authAgeNotConfirmed), findsOneWidget);
+        verifyNever(() => repository.signUp(any()));
+      },
+    );
+
+    testWidgets('QUE-04 Kriterium 1: without consent the error shows', (
+      tester,
+    ) async {
+      await open(tester);
+      await fillValid(tester);
+      await tapKey(tester, 'register_terms_checkbox');
+
+      await submit(tester);
+
+      expect(find.text(_de.authTermsNotAccepted), findsOneWidget);
+      verifyNever(() => repository.signUp(any()));
+    });
+  });
+
+  group('KTO-01 Kriterium 3: password at the field', () {
+    testWidgets('shows the missing characters while typing', (tester) async {
+      await open(tester);
+
+      await type(tester, 'register_password', 'abc');
+
+      expect(find.text(_de.authPasswordTooShort(7)), findsOneWidget);
+      await type(tester, 'register_password', 'abcdefghi');
+      expect(find.text(_de.authPasswordTooShort(1)), findsOneWidget);
+      await type(tester, 'register_password', 'abcdefghij');
+      expect(find.textContaining('Mindestens 10 Zeichen –'), findsNothing);
+    });
+
+    testWidgets('names a common password', (tester) async {
+      await open(tester);
+
+      await type(tester, 'register_password', 'Passwort1234');
+      await tester.pumpAndSettle();
+
+      expect(find.text(_de.authPasswordCommon), findsOneWidget);
+    });
+
+    testWidgets('shows the rule as hint before any error', (tester) async {
+      await open(tester);
+      expect(find.text(_de.authPasswordRule), findsOneWidget);
+    });
+
+    testWidgets('a weak_password answer shows at the field', (tester) async {
+      when(() => repository.signUp(any())).thenAnswer(
+        (_) async =>
+            failed(const AuthFailure.weakPassword([WeakPasswordReason.length])),
+      );
+      await open(tester);
+      await fillValid(tester);
+
+      await submit(tester);
+
+      expect(find.text(_de.authErrorWeakPasswordLength), findsOneWidget);
+      expect(find.byKey(const Key('register_banner')), findsNothing);
+    });
+  });
+
+  group('KTO-01 Kriterium 10: display name at the field', () {
+    testWidgets('empty name shows the error on submit', (tester) async {
+      await open(tester);
+      await type(tester, 'register_email', 'anna@example.com');
+      await type(tester, 'register_password', 'geheim-und-lang');
+
+      await submit(tester);
+
+      expect(find.text(_de.authDisplayNameEmpty), findsOneWidget);
+      verifyNever(() => repository.signUp(any()));
+    });
+
+    testWidgets('31 characters are too long, the counter follows', (
+      tester,
+    ) async {
+      await open(tester);
+
+      await type(tester, 'register_display_name', 'a' * 31);
+      await tester.testTextInput.receiveAction(TextInputAction.done);
+      await tester.pumpAndSettle();
+
+      expect(find.text(_de.authDisplayNameTooLong(30)), findsOneWidget);
+      expect(find.text('31/30'), findsOneWidget);
+    });
+
+    testWidgets('the counter counts trimmed code points', (tester) async {
+      await open(tester);
+
+      await type(tester, 'register_display_name', '  😀😀  ');
+
+      expect(find.text('2/30'), findsOneWidget);
+    });
+
+    testWidgets('U+200B shows the same message as an invalid name', (
+      tester,
+    ) async {
+      await open(tester);
+
+      await type(tester, 'register_display_name', 'A​B');
+      await tester.testTextInput.receiveAction(TextInputAction.done);
+      await tester.pumpAndSettle();
+
+      expect(find.text(_de.authDisplayNameInvalid), findsOneWidget);
+    });
+  });
+
+  group('KTO-01 Kriterium 1: email at the field', () {
+    testWidgets('an invalid address shows after leaving the field', (
+      tester,
+    ) async {
+      await open(tester);
+
+      await type(tester, 'register_email', 'anna');
+      await tester.tap(fieldOf('register_password'));
+      await tester.pumpAndSettle();
+
+      expect(find.text(_de.authErrorEmailInvalid), findsOneWidget);
+    });
+
+    testWidgets('after a failed submit the first invalid field has focus', (
+      tester,
+    ) async {
+      await open(tester);
+
+      await submit(tester);
+
+      final email = tester.widget<TextField>(fieldOf('register_email'));
+      expect(email.focusNode?.hasFocus, isTrue);
+    });
+  });
+
+  group('KTO-01 Kriterium 4 (F12): same screen for every answer', () {
+    Future<List<String>> textsAfterSubmit(
+      WidgetTester tester,
+      Result<void, AuthFailure> answer,
+    ) async {
+      when(() => repository.signUp(any())).thenAnswer((_) async => answer);
+      final (:container, :router) = await open(tester);
+      await fillValid(tester);
+      await submit(tester);
+      expect(currentPath(router), '/register/check-email');
+      final texts = visibleTexts(tester);
+      // Unmount so that provider disposal timers run before the next pump.
+      await tester.pumpWidget(const SizedBox.shrink());
+      await tester.pumpAndSettle();
+      return texts;
+    }
+
+    testWidgets('success and emailSendLimited show identical texts', (
+      tester,
+    ) async {
+      final success = await textsAfterSubmit(tester, ok());
+      final limited = await textsAfterSubmit(
+        tester,
+        failed(const AuthFailure.emailSendLimited()),
+      );
+
+      expect(limited, success);
+      expect(limited, isNot(contains(_de.authErrorRateLimited)));
+      expect(limited, contains(_de.authCheckEmailDelayHint));
+    });
+  });
+
+  group('Zustände Kriterium 2, 3: loading, errors, offline', () {
+    testWidgets('while sending the button and fields are locked', (
+      tester,
+    ) async {
+      final completer = Completer<Result<void, AuthFailure>>();
+      when(() => repository.signUp(any())).thenAnswer((_) => completer.future);
+      await open(tester);
+      await fillValid(tester);
+
+      await tapKey(tester, 'register_submit');
+      await tester.pump();
+
+      expect(find.byType(CircularProgressIndicator), findsOneWidget);
+      expect(
+        tester.widget<TextField>(fieldOf('register_email')).enabled,
+        false,
+      );
+      final button = tester.widget<FilledButton>(
+        find.descendant(
+          of: find.byKey(const Key('register_submit')),
+          matching: find.byType(FilledButton),
+        ),
+      );
+      expect(button.onPressed, isNull);
+
+      completer.complete(ok());
+      await tester.pumpAndSettle();
+    });
+
+    testWidgets('offline: shows the hint, keeps the input, can retry', (
+      tester,
+    ) async {
+      when(() => repository.signUp(any()))
+          .thenAnswer((_) async => failed(const AuthFailure.network()));
+      final (:container, :router) = await open(tester);
+      await fillValid(tester);
+
+      await submit(tester);
+
+      expect(find.text(_de.authErrorNetwork), findsOneWidget);
+      expect(currentPath(router), '/register');
+      expect(
+        tester.widget<TextField>(fieldOf('register_email')).controller?.text,
+        'anna@example.com',
+      );
+      expect(
+        tester.widget<TextField>(fieldOf('register_password')).controller?.text,
+        'geheim-und-lang',
+      );
+
+      when(() => repository.signUp(any())).thenAnswer((_) async => ok());
+      await tester.tap(find.text(_de.authActionRetry));
+      await tester.pumpAndSettle();
+      expect(currentPath(router), '/register/check-email');
+    });
+
+    testWidgets('a rejected registration shows the general message', (
+      tester,
+    ) async {
+      when(() => repository.signUp(any())).thenAnswer(
+        (_) async => failed(const AuthFailure.registrationRejected()),
+      );
+      await open(tester);
+      await fillValid(tester);
+
+      await submit(tester);
+
+      expect(find.text(_de.authErrorRegistrationRejected), findsOneWidget);
+    });
+  });
+
+  group('QUE-04 Kriterium 1: legal links', () {
+    testWidgets('privacy and terms open the configured URLs', (tester) async {
+      final opened = <Uri>[];
+      await open(
+        tester,
+        urlOpener: (uri) async {
+          opened.add(uri);
+          return true;
+        },
+      );
+
+      await tester.ensureVisible(find.text(_de.authCheckboxTermsPrivacyLink));
+      await tester.tap(find.text(_de.authCheckboxTermsPrivacyLink));
+      await tester.tap(find.text(_de.authCheckboxTermsTermsLink));
+      await tester.pump();
+
+      expect(opened, [
+        Uri.parse(testAppConfig().legalPrivacyUrl),
+        Uri.parse(testAppConfig().legalTermsUrl),
+      ]);
+      // Opening a link does not tick the box.
+      final handle = tester.ensureSemantics();
+      expect(
+        tester.getSemantics(find.byKey(const Key('register_terms_checkbox'))),
+        isNot(matchesSemantics(isChecked: true)),
+      );
+      handle.dispose();
+    });
+
+    testWidgets('a failing launch shows a hint', (tester) async {
+      await open(tester, urlOpener: (_) async => false);
+
+      await tester.ensureVisible(find.text(_de.authCheckboxTermsTermsLink));
+      await tester.tap(find.text(_de.authCheckboxTermsTermsLink));
+      await tester.pump();
+
+      expect(find.text(_de.authErrorUnexpected), findsOneWidget);
+    });
+  });
+
+  group('QUE-05 Kriterium 2: de and en', () {
+    testWidgets(
+      'KTO-01 Kriterium 11 (Client): english texts and english mail language',
+      (tester) async {
+        await open(tester, locale: const Locale('en'));
+
+        expect(find.text(_en.authRegisterTitle), findsWidgets);
+        expect(find.text(_en.authFieldDisplayNameLabel), findsOneWidget);
+        expect(find.text(_en.authCheckboxAgeLabel), findsOneWidget);
+        expect(find.text(_de.authCheckboxAgeLabel), findsNothing);
+
+        await fillValid(tester);
+        await submit(tester);
+        final input =
+            verify(() => repository.signUp(captureAny())).captured.single
+                as RegistrationInput;
+        expect(input.locale, 'en');
+        expect(find.text(_en.authCheckEmailTitle), findsWidgets);
+      },
+    );
+
+    testWidgets('german texts and the sentence with both links', (
+      tester,
+    ) async {
+      await open(tester);
+
+      expect(find.text(_de.authFieldPasswordLabel), findsOneWidget);
+      final handle = tester.ensureSemantics();
+      expect(
+        find.bySemanticsLabel(
+          'Ich habe die Datenschutzerklärung gelesen und stimme den '
+          'Nutzungsbedingungen zu',
+        ),
+        findsOneWidget,
+      );
+      handle.dispose();
+    });
+  });
+
+  group('QUE-06 Kriterien 1-4: accessibility', () {
+    for (final mode in [ThemeMode.light, ThemeMode.dark]) {
+      testWidgets('meets the guidelines ($mode)', (tester) async {
+        final handle = tester.ensureSemantics();
+        await open(tester, themeMode: mode);
+        await submit(tester);
+
+        await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
+        await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
+        await expectLater(tester, meetsGuideline(textContrastGuideline));
+        handle.dispose();
+      });
+    }
+
+    testWidgets('text scale 2.0 on a small phone does not overflow', (
+      tester,
+    ) async {
+      await open(tester, textScale: 2, size: const Size(320, 640));
+      await submit(tester);
+
+      expect(tester.takeException(), isNull);
+    });
+
+    testWidgets('wide screens show a centered card', (tester) async {
+      await open(tester, size: const Size(1200, 900));
+
+      final card = tester.getRect(find.byType(Card).first);
+      expect(card.width, lessThanOrEqualTo(480));
+      expect(card.center.dx, closeTo(600, 1));
+    });
+  });
+}

docs/design-system.md

@@ -71,7 +71,7 @@ getestet; Tests liegen in `app/test/core/widgets/` und dienen als lauffähige Vo
 
 | Komponente | Zweck und API (Kurzform) |
 |---|---|
-| `AppTextField` | `label` (sichtbar über dem Feld, umbrechend, auch Semantics-Label), `helperText`, `errorText` (ersetzt Hilfetext), `controller`, `focusNode`, `keyboardType`, `textInputAction`, `autofillHints`, `maxLength` + `showCounter` (weiche Grenze: Eingabe wird nicht abgeschnitten, damit der Fehler am Feld erscheint), `inputFormatters`, `enabled`, `onChanged`, `onSubmitted`. |
+| `AppTextField` | `label` (sichtbar über dem Feld, umbrechend, auch Semantics-Label), `helperText`, `errorText` (ersetzt Hilfetext), `controller`, `focusNode`, `keyboardType`, `textInputAction`, `autofillHints`, `maxLength` + `showCounter` (weiche Grenze: Eingabe wird nicht abgeschnitten, damit der Fehler am Feld erscheint), `counterText` (eigener Zählertext, wenn die Zähleinheit vom Standard abweicht, z. B. getrimmte Codepoints beim Anzeigenamen), `inputFormatters`, `enabled`, `onChanged`, `onSubmitted`. |
 | `AppPasswordField` | Wie `AppTextField`, dazu `showPasswordLabel` / `hidePasswordLabel` (Pflicht; Tooltip + Semantics des 48-dp-Schalters), `ruleHint` (Regelhinweis, solange kein Fehler), `isNewPassword` (Autofill `newPassword` statt `password`), `autofillHints` zum Überschreiben. Startet verdeckt, Autokorrektur und Vorschläge aus. |
 | `AppCheckboxField` | `AppCheckboxField(value, onChanged, label)` bzw. `.rich(segments: [AppLabelSegment.text(..), AppLabelSegment.link(text, onTap)])`, `errorText`. Ganze Zeile (Checkbox + Label) ist Touch-Ziel >= 48 dp. Links sind per Tastatur fokussierbar und für Screenreader als benutzerdefinierte Aktionen verfügbar; Semantics-Knoten meldet Zustand und den vollen Labeltext. |
 | `AppPrimaryButton` | `label`, `onPressed`, `isLoading` (deaktiviert + Spinner, kein Doppelsenden), `loadingLabel` (gesprochener Text im Ladezustand), `icon`, `expand` (Standard: volle Breite). |