feat(frontend): add responsive design, form validation, toast service and error handling

- Responsive navigation with mobile hamburger menu
- Reactive forms with real-time validation on profile page
- Toast service for success/error/warning messages
- HTTP error interceptor for 401/403/500 handling
- Loading states with spinner animations

eeg_frontend/src/app/app.config.ts

@@ -4,13 +4,14 @@ import {routes} from './app.routes';
 import {provideHttpClient, withFetch, withInterceptors} from '@angular/common/http';
 import {BASE_PATH} from './api';
 import {jwtInterceptor} from './interceptors/jwt.interceptor';
+import {errorInterceptor} from './interceptors/error.interceptor';
 
 export const appConfig: ApplicationConfig = {
   providers: [
     provideZoneChangeDetection({ eventCoalescing: true }),
     provideRouter(routes),
     provideHttpClient(withFetch(),
-      withInterceptors([jwtInterceptor])),
+      withInterceptors([jwtInterceptor, errorInterceptor])),
     { provide: BASE_PATH, useValue: 'http://localhost:8080' }
   ]
 };

eeg_frontend/src/app/app.html

@@ -4,3 +4,4 @@
 <main class="min-h-[calc(100vh-4rem)] bg-gray-50">
   <router-outlet></router-outlet>
 </main>
+<app-toast></app-toast>

eeg_frontend/src/app/app.ts

@@ -1,10 +1,11 @@
 import {Component, signal} from '@angular/core';
 import {NavigationEnd, Router, RouterOutlet} from '@angular/router';
 import {HeaderComponent} from './layout/header/header';
+import {ToastComponent} from './components/toast/toast';
 
 @Component({
   selector: 'app-root',
-  imports: [RouterOutlet, HeaderComponent],
+  imports: [RouterOutlet, HeaderComponent, ToastComponent],
   templateUrl: './app.html',
   styleUrl: './app.scss',
 })

eeg_frontend/src/app/components/toast/toast.ts

@@ -0,0 +1,44 @@
+import { Component, inject } from '@angular/core';
+import { ToastService } from '../../services/toast';
+
+@Component({
+  selector: 'app-toast',
+  standalone: true,
+  template: `
+    <div class="fixed bottom-4 right-4 z-50 space-y-2">
+      @for (toast of toastService.toasts$(); track toast.id) {
+        <div
+          class="px-4 py-3 rounded-lg shadow-lg text-white text-sm font-medium max-w-sm animate-slide-in"
+          [class]="getToastClass(toast.type)">
+          {{ toast.message }}
+          <button
+            (click)="toastService.dismiss(toast.id)"
+            class="ml-2 text-white opacity-70 hover:opacity-100">
+            ×
+          </button>
+        </div>
+      }
+    </div>
+  `,
+  styles: [`
+    @keyframes slide-in {
+      from { transform: translateX(100%); opacity: 0; }
+      to { transform: translateX(0); opacity: 1; }
+    }
+    .animate-slide-in {
+      animation: slide-in 0.3s ease-out;
+    }
+  `]
+})
+export class ToastComponent {
+  toastService = inject(ToastService);
+
+  getToastClass(type: string): string {
+    switch (type) {
+      case 'success': return 'bg-green-500';
+      case 'error': return 'bg-red-500';
+      case 'warning': return 'bg-yellow-500';
+      default: return 'bg-blue-500';
+    }
+  }
+}

eeg_frontend/src/app/interceptors/error.interceptor.ts

@@ -0,0 +1,31 @@
+import { HttpInterceptorFn } from '@angular/common/http';
+import { inject } from '@angular/core';
+import { Router } from '@angular/router';
+import { catchError, throwError } from 'rxjs';
+import { AuthService } from '../services/auth';
+import { ToastService } from '../services/toast';
+
+export const errorInterceptor: HttpInterceptorFn = (req, next) => {
+  const router = inject(Router);
+  const authService = inject(AuthService);
+  const toastService = inject(ToastService);
+
+  return next(req).pipe(
+    catchError(error => {
+      if (error.status === 401) {
+        // Unauthorized - auto logout
+        authService.logout();
+        router.navigate(['/login']);
+        toastService.error('Sitzung abgelaufen. Bitte erneut einloggen.');
+      } else if (error.status === 403) {
+        toastService.error('Keine Berechtigung für diese Aktion.');
+      } else if (error.status === 404) {
+        toastService.error('Ressource nicht gefunden.');
+      } else if (error.status >= 500) {
+        toastService.error('Ein Serverfehler ist aufgetreten. Bitte versuchen Sie es später erneut.');
+      }
+
+      return throwError(() => error);
+    })
+  );
+};

eeg_frontend/src/app/layout/dashboard-layout/dashboard-layout.html

@@ -1,6 +1,15 @@
 <div class="flex h-screen bg-slate-50">
 
-  <aside class="w-64 bg-white border-r border-slate-200 flex flex-col z-10 shrink-0">
+  <!-- Mobile Overlay -->
+  @if (isMobileMenuOpen()) {
+    <div class="fixed inset-0 bg-black bg-opacity-50 z-20 md:hidden"
+         (click)="closeMobileMenu()"></div>
+  }
+
+  <!-- Sidebar -->
+  <aside [class]="isMobileMenuOpen()
+    ? 'fixed inset-y-0 left-0 w-64 bg-white border-r border-slate-200 flex flex-col z-30 transform transition-transform duration-200 ease-in-out'
+    : 'fixed inset-y-0 left-0 w-64 bg-white border-r border-slate-200 flex flex-col z-30 transform transition-transform duration-200 ease-in-out -translate-x-full md:translate-x-0 md:static md:z-10'">
     <div class="h-16 flex items-center px-6 border-b border-slate-200 shrink-0">
       <a routerLink="/" class="flex items-center space-x-2 group">
         <svg class="h-7 w-7 text-emerald-600" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2">
@@ -17,6 +26,7 @@
         <a [routerLink]="item.path"
            routerLinkActive="bg-emerald-50 text-emerald-700 font-medium"
            [routerLinkActiveOptions]="{exact: item.path === '/dashboard'}"
+           (click)="closeMobileMenu()"
            class="block px-4 py-2.5 rounded-lg text-slate-600 hover:bg-slate-50 hover:text-slate-900 transition-colors">
           {{ item.label }}
         </a>
@@ -26,13 +36,21 @@
 
   <main class="flex-1 flex flex-col min-w-0 overflow-hidden">
 
-    <header class="h-16 bg-white border-b border-slate-200 flex items-center px-8 justify-between shrink-0">
+    <header class="h-16 bg-white border-b border-slate-200 flex items-center px-4 md:px-8 justify-between shrink-0">
-      <h1 class="text-lg font-semibold text-slate-800">
+      <!-- Mobile Menu Button -->
+      <button (click)="toggleMobileMenu()"
+              class="md:hidden p-2 rounded-md text-slate-600 hover:text-slate-900 hover:bg-slate-100">
+        <svg class="h-6 w-6" fill="none" viewBox="0 0 24 24" stroke="currentColor">
+          <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 6h16M4 12h16M4 18h16" />
+        </svg>
+      </button>
+
+      <h1 class="text-lg font-semibold text-slate-800 hidden md:block">
         {{ authService.currentUserRole() === 'ADMIN' ? 'Verwaltung' : 'Mein Bereich' }}
       </h1>
 
       <div class="flex items-center gap-4">
-    <span class="text-sm text-gray-500">
+        <span class="text-sm text-gray-500 hidden sm:inline">
           Rolle: <span class="font-semibold text-gray-700">{{ authService.currentUserRole() }}</span>
         </span>
         <button (click)="onLogout()"
@@ -42,7 +60,7 @@
       </div>
     </header>
 
-    <div class="flex-1 overflow-auto p-8">
+    <div class="flex-1 overflow-auto p-4 md:p-8">
       <router-outlet></router-outlet>
     </div>
 

eeg_frontend/src/app/layout/dashboard-layout/dashboard-layout.ts

@@ -1,4 +1,4 @@
-import {Component, computed, inject} from '@angular/core';
+import {Component, computed, inject, signal} from '@angular/core';
 import {Router, RouterLink, RouterLinkActive, RouterOutlet} from '@angular/router';
 import {AuthService} from '../../services/auth';
 import {NAV_ITEMS} from './dashboard-nav-items';
@@ -14,11 +14,21 @@ export class DashboardLayout {
   authService = inject(AuthService);
   private router = inject(Router);
 
+  isMobileMenuOpen = signal(false);
+
   visibleNavItems = computed(() => {
     const role = this.authService.currentUserRole();
     return NAV_ITEMS.filter(item => role !== null && item.roles.includes(role));
   });
 
+  toggleMobileMenu() {
+    this.isMobileMenuOpen.update(v => !v);
+  }
+
+  closeMobileMenu() {
+    this.isMobileMenuOpen.set(false);
+  }
+
   onLogout() {
     this.authService.logout();
     this.router.navigate(['/']);

eeg_frontend/src/app/pages/profile/profile.html

@@ -1,48 +1,46 @@
-<div class="max-w-2xl mx-auto p-6">
+<div class="max-w-2xl mx-auto p-4 md:p-6">
   <h1 class="text-2xl font-bold mb-6">Mein Profil</h1>
 
   @if (isLoading()) {
-    <div class="text-center py-8 text-gray-500">Lade Profil...</div>
+    <div class="text-center py-8 text-gray-500">
+      <div class="inline-block animate-spin rounded-full h-8 w-8 border-b-2 border-gray-900 mb-2"></div>
+      <div>Lade Profil...</div>
+    </div>
   } @else if (profile()) {
-    <!-- Erfolg/Fehler-Meldungen -->
-    @if (successMessage()) {
-      <div class="bg-green-100 border border-green-400 text-green-700 px-4 py-3 rounded mb-4">
-        {{ successMessage() }}
-      </div>
-    }
-    @if (errorMessage()) {
-      <div class="bg-red-100 border border-red-400 text-red-700 px-4 py-3 rounded mb-4">
-        {{ errorMessage() }}
-      </div>
-    }
-
     <!-- Profil-Informationen -->
     <div class="bg-white shadow rounded-lg p-6 mb-6">
       <h2 class="text-lg font-semibold mb-4">Persönliche Daten</h2>
 
-      <div class="grid grid-cols-2 gap-4">
+      <form [formGroup]="profileForm" (ngSubmit)="updateProfile()">
+        <div class="grid grid-cols-1 md:grid-cols-2 gap-4">
           <div>
-          <label class="block text-sm font-medium text-gray-700 mb-1">Vorname</label>
+            <label class="block text-sm font-medium text-gray-700 mb-1">Vorname *</label>
-          <input type="text" [(ngModel)]="editFirstName"
+            <input type="text" formControlName="firstName"
-                 class="w-full border border-gray-300 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500" />
+                   [class]="isFieldInvalid(profileForm, 'firstName') ? 'w-full border border-red-500 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-red-500' : 'w-full border border-gray-300 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500'" />
+            @if (isFieldInvalid(profileForm, 'firstName')) {
+              <p class="text-red-500 text-xs mt-1">Vorname ist erforderlich (min. 2 Zeichen)</p>
+            }
           </div>
           <div>
-          <label class="block text-sm font-medium text-gray-700 mb-1">Nachname</label>
+            <label class="block text-sm font-medium text-gray-700 mb-1">Nachname *</label>
-          <input type="text" [(ngModel)]="editLastName"
+            <input type="text" formControlName="lastName"
-                 class="w-full border border-gray-300 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500" />
+                   [class]="isFieldInvalid(profileForm, 'lastName') ? 'w-full border border-red-500 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-red-500' : 'w-full border border-gray-300 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500'" />
+            @if (isFieldInvalid(profileForm, 'lastName')) {
+              <p class="text-red-500 text-xs mt-1">Nachname ist erforderlich (min. 2 Zeichen)</p>
+            }
           </div>
           <div>
             <label class="block text-sm font-medium text-gray-700 mb-1">Teilnehmertyp</label>
-          <select [(ngModel)]="editParticipantType"
+            <select formControlName="participantType"
                     class="w-full border border-gray-300 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500">
               <option value="PRIVATE">Privatperson</option>
               <option value="COMPANY">Juristische Person</option>
             </select>
           </div>
-        @if (editParticipantType === 'COMPANY') {
+          @if (profileForm.get('participantType')?.value === 'COMPANY') {
             <div>
               <label class="block text-sm font-medium text-gray-700 mb-1">Organisationsname</label>
-            <input type="text" [(ngModel)]="editOrganizationName"
+              <input type="text" formControlName="organizationName"
                      class="w-full border border-gray-300 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500" />
             </div>
           }
@@ -53,54 +51,65 @@
           <div class="text-gray-900">{{ profile()!.email }}</div>
         </div>
 
-      <button (click)="updateProfile()" [disabled]="isSaving()"
+        <button type="submit" [disabled]="isSaving() || profileForm.invalid"
                 class="mt-4 bg-blue-600 text-white px-4 py-2 rounded-md hover:bg-blue-700 disabled:opacity-50">
           {{ isSaving() ? 'Speichere...' : 'Profil speichern' }}
         </button>
+      </form>
     </div>
 
     <!-- Passwort ändern -->
     <div class="bg-white shadow rounded-lg p-6 mb-6">
       <h2 class="text-lg font-semibold mb-4">Passwort ändern</h2>
 
+      <form [formGroup]="passwordForm" (ngSubmit)="changePassword()">
         <div class="space-y-4">
           <div>
-          <label class="block text-sm font-medium text-gray-700 mb-1">Aktuelles Passwort</label>
+            <label class="block text-sm font-medium text-gray-700 mb-1">Aktuelles Passwort *</label>
-          <input type="password" [(ngModel)]="currentPassword"
+            <input type="password" formControlName="currentPassword"
-                 class="w-full border border-gray-300 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500" />
+                   [class]="isFieldInvalid(passwordForm, 'currentPassword') ? 'w-full border border-red-500 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-red-500' : 'w-full border border-gray-300 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500'" />
           </div>
           <div>
-          <label class="block text-sm font-medium text-gray-700 mb-1">Neues Passwort</label>
+            <label class="block text-sm font-medium text-gray-700 mb-1">Neues Passwort *</label>
-          <input type="password" [(ngModel)]="newPassword"
+            <input type="password" formControlName="newPassword"
-                 class="w-full border border-gray-300 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500" />
+                   [class]="isFieldInvalid(passwordForm, 'newPassword') ? 'w-full border border-red-500 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-red-500' : 'w-full border border-gray-300 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500'" />
+            @if (isFieldInvalid(passwordForm, 'newPassword')) {
+              <p class="text-red-500 text-xs mt-1">Passwort muss mindestens 8 Zeichen lang sein</p>
+            }
           </div>
           <div>
-          <label class="block text-sm font-medium text-gray-700 mb-1">Neues Passwort bestätigen</label>
+            <label class="block text-sm font-medium text-gray-700 mb-1">Neues Passwort bestätigen *</label>
-          <input type="password" [(ngModel)]="newPasswordConfirm"
+            <input type="password" formControlName="newPasswordConfirm"
-                 class="w-full border border-gray-300 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500" />
+                   [class]="isFieldInvalid(passwordForm, 'newPasswordConfirm') ? 'w-full border border-red-500 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-red-500' : 'w-full border border-gray-300 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500'" />
           </div>
         </div>
 
-      <button (click)="changePassword()" [disabled]="isSaving()"
+        <button type="submit" [disabled]="isSaving() || passwordForm.invalid"
                 class="mt-4 bg-blue-600 text-white px-4 py-2 rounded-md hover:bg-blue-700 disabled:opacity-50">
           {{ isSaving() ? 'Ändere...' : 'Passwort ändern' }}
         </button>
+      </form>
     </div>
 
     <!-- E-Mail ändern -->
     <div class="bg-white shadow rounded-lg p-6">
       <h2 class="text-lg font-semibold mb-4">E-Mail-Adresse ändern</h2>
 
+      <form [formGroup]="emailForm" (ngSubmit)="changeEmail()">
         <div>
-        <label class="block text-sm font-medium text-gray-700 mb-1">Neue E-Mail-Adresse</label>
+          <label class="block text-sm font-medium text-gray-700 mb-1">Neue E-Mail-Adresse *</label>
-        <input type="email" [(ngModel)]="newEmail" placeholder="neu@example.com"
+          <input type="email" formControlName="newEmail" placeholder="neu@example.com"
-               class="w-full border border-gray-300 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500" />
+                 [class]="isFieldInvalid(emailForm, 'newEmail') ? 'w-full border border-red-500 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-red-500' : 'w-full border border-gray-300 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500'" />
+          @if (isFieldInvalid(emailForm, 'newEmail')) {
+            <p class="text-red-500 text-xs mt-1">Bitte geben Sie eine gültige E-Mail-Adresse ein</p>
+          }
         </div>
 
-      <button (click)="changeEmail()" [disabled]="isSaving()"
+        <button type="submit" [disabled]="isSaving() || emailForm.invalid"
                 class="mt-4 bg-blue-600 text-white px-4 py-2 rounded-md hover:bg-blue-700 disabled:opacity-50">
           {{ isSaving() ? 'Ändere...' : 'E-Mail ändern' }}
         </button>
+      </form>
     </div>
   }
 </div>

eeg_frontend/src/app/pages/profile/profile.ts

@@ -1,32 +1,39 @@
 import {Component, inject, OnInit, signal} from '@angular/core';
-import {FormsModule} from '@angular/forms';
+import {ReactiveFormsModule, FormBuilder, FormGroup, Validators} from '@angular/forms';
 import {UserService, UserProfile, UpdateProfileRequest} from '../../services/user';
+import {ToastService} from '../../services/toast';
 
 @Component({
   selector: 'app-profile',
   standalone: true,
-  imports: [FormsModule],
+  imports: [ReactiveFormsModule],
   templateUrl: './profile.html'
 })
 export class ProfileComponent implements OnInit {
   private userService = inject(UserService);
+  private fb = inject(FormBuilder);
+  private toastService = inject(ToastService);
 
   profile = signal<UserProfile | null>(null);
   isLoading = signal(true);
   isSaving = signal(false);
-  successMessage = signal('');
-  errorMessage = signal('');
 
-  editFirstName = '';
+  profileForm: FormGroup = this.fb.group({
-  editLastName = '';
+    firstName: ['', [Validators.required, Validators.minLength(2)]],
-  editOrganizationName = '';
+    lastName: ['', [Validators.required, Validators.minLength(2)]],
-  editParticipantType = 'PRIVATE';
+    organizationName: [''],
+    participantType: ['PRIVATE']
+  });
 
-  currentPassword = '';
+  passwordForm: FormGroup = this.fb.group({
-  newPassword = '';
+    currentPassword: ['', [Validators.required]],
-  newPasswordConfirm = '';
+    newPassword: ['', [Validators.required, Validators.minLength(8)]],
+    newPasswordConfirm: ['', [Validators.required]]
+  });
 
-  newEmail = '';
+  emailForm: FormGroup = this.fb.group({
+    newEmail: ['', [Validators.required, Validators.email]]
+  });
 
   ngOnInit() {
     this.loadProfile();
@@ -36,10 +43,12 @@ export class ProfileComponent implements OnInit {
     this.userService.getProfile().subscribe({
       next: profile => {
         this.profile.set(profile);
-        this.editFirstName = profile.firstName || '';
+        this.profileForm.patchValue({
-        this.editLastName = profile.lastName || '';
+          firstName: profile.firstName || '',
-        this.editOrganizationName = profile.organizationName || '';
+          lastName: profile.lastName || '',
-        this.editParticipantType = profile.participantType;
+          organizationName: profile.organizationName || '',
+          participantType: profile.participantType
+        });
         this.isLoading.set(false);
       },
       error: () => this.isLoading.set(false)
@@ -47,76 +56,69 @@ export class ProfileComponent implements OnInit {
   }
 
   updateProfile() {
-    if (this.isSaving()) return;
+    if (this.isSaving() || this.profileForm.invalid) return;
     this.isSaving.set(true);
-    this.successMessage.set('');
-    this.errorMessage.set('');
 
-    const request: UpdateProfileRequest = {
+    const request: UpdateProfileRequest = this.profileForm.value;
-      firstName: this.editFirstName,
-      lastName: this.editLastName,
-      organizationName: this.editOrganizationName || undefined,
-      participantType: this.editParticipantType as 'PRIVATE' | 'COMPANY'
-    };
 
     this.userService.updateProfile(request).subscribe({
       next: profile => {
         this.profile.set(profile);
         this.isSaving.set(false);
-        this.successMessage.set('Profil erfolgreich aktualisiert.');
+        this.toastService.success('Profil erfolgreich aktualisiert.');
       },
       error: (err) => {
         this.isSaving.set(false);
-        this.errorMessage.set(err.error?.message || 'Fehler beim Aktualisieren.');
+        this.toastService.error(err.error?.message || 'Fehler beim Aktualisieren.');
       }
     });
   }
 
   changePassword() {
-    if (this.isSaving() || !this.currentPassword || !this.newPassword) return;
+    if (this.isSaving() || this.passwordForm.invalid) return;
-    if (this.newPassword !== this.newPasswordConfirm) {
+
-      this.errorMessage.set('Passwörter stimmen nicht überein.');
+    if (this.passwordForm.value.newPassword !== this.passwordForm.value.newPasswordConfirm) {
+      this.toastService.warning('Passwörter stimmen nicht überein.');
       return;
     }
 
     this.isSaving.set(true);
-    this.successMessage.set('');
-    this.errorMessage.set('');
 
     this.userService.changePassword({
-      currentPassword: this.currentPassword,
+      currentPassword: this.passwordForm.value.currentPassword,
-      newPassword: this.newPassword
+      newPassword: this.passwordForm.value.newPassword
     }).subscribe({
       next: () => {
         this.isSaving.set(false);
-        this.successMessage.set('Passwort erfolgreich geändert.');
+        this.toastService.success('Passwort erfolgreich geändert.');
-        this.currentPassword = '';
+        this.passwordForm.reset();
-        this.newPassword = '';
-        this.newPasswordConfirm = '';
       },
       error: (err) => {
         this.isSaving.set(false);
-        this.errorMessage.set(err.error?.message || 'Fehler beim Ändern des Passworts.');
+        this.toastService.error(err.error?.message || 'Fehler beim Ändern des Passworts.');
       }
     });
   }
 
   changeEmail() {
-    if (this.isSaving() || !this.newEmail) return;
+    if (this.isSaving() || this.emailForm.invalid) return;
     this.isSaving.set(true);
-    this.successMessage.set('');
-    this.errorMessage.set('');
 
-    this.userService.changeEmail({newEmail: this.newEmail}).subscribe({
+    this.userService.changeEmail({newEmail: this.emailForm.value.newEmail}).subscribe({
       next: () => {
         this.isSaving.set(false);
-        this.successMessage.set('E-Mail-Adresse geändert. Bitte neue Adresse verifizieren.');
+        this.toastService.success('E-Mail-Adresse geändert. Bitte neue Adresse verifizieren.');
-        this.newEmail = '';
+        this.emailForm.reset();
       },
       error: (err) => {
         this.isSaving.set(false);
-        this.errorMessage.set(err.error?.message || 'Fehler beim Ändern der E-Mail.');
+        this.toastService.error(err.error?.message || 'Fehler beim Ändern der E-Mail.');
       }
     });
   }
+
+  isFieldInvalid(form: FormGroup, fieldName: string): boolean {
+    const field = form.get(fieldName);
+    return !!(field && field.invalid && (field.dirty || field.touched));
+  }
 }

eeg_frontend/src/app/services/toast.ts

@@ -0,0 +1,50 @@
+import { Injectable, signal } from '@angular/core';
+
+export interface Toast {
+  id: number;
+  message: string;
+  type: 'success' | 'error' | 'warning' | 'info';
+}
+
+@Injectable({ providedIn: 'root' })
+export class ToastService {
+  private toasts = signal<Toast[]>([]);
+  private nextId = 0;
+
+  get toasts$() {
+    return this.toasts.asReadonly();
+  }
+
+  show(message: string, type: Toast['type'] = 'info', duration = 3000) {
+    const id = this.nextId++;
+    const toast: Toast = { id, message, type };
+
+    this.toasts.update(toasts => [...toasts, toast]);
+
+    if (duration > 0) {
+      setTimeout(() => this.dismiss(id), duration);
+    }
+
+    return id;
+  }
+
+  success(message: string, duration = 3000) {
+    return this.show(message, 'success', duration);
+  }
+
+  error(message: string, duration = 5000) {
+    return this.show(message, 'error', duration);
+  }
+
+  warning(message: string, duration = 4000) {
+    return this.show(message, 'warning', duration);
+  }
+
+  dismiss(id: number) {
+    this.toasts.update(toasts => toasts.filter(t => t.id !== id));
+  }
+
+  clear() {
+    this.toasts.set([]);
+  }
+}