apps/frontend/src/app/app.config.ts

@@ -2,6 +2,7 @@ import {
   ApplicationConfig,
   provideBrowserGlobalErrorListeners,
   APP_INITIALIZER,
+  ErrorHandler,
 } from '@angular/core';
 import { provideRouter } from '@angular/router';
 import { provideHttpClient, withInterceptors, HTTP_INTERCEPTORS } from '@angular/common/http';
@@ -9,12 +10,17 @@ import { appRoutes } from './app.routes';
 import { AuthService } from './services/auth.service';
 import { AuthInterceptor } from './interceptors/auth.interceptor';
 import { initializeAuth } from './initializers/auth.initializer';
+import { GlobalErrorHandler } from './services/global-error-handler.service';
 
 export const appConfig: ApplicationConfig = {
   providers: [
     provideBrowserGlobalErrorListeners(),
     provideRouter(appRoutes),
     provideHttpClient(),
+    {
+      provide: ErrorHandler,
+      useClass: GlobalErrorHandler
+    },
     {
       provide: HTTP_INTERCEPTORS,
       useClass: AuthInterceptor,

apps/frontend/src/app/app.html

@@ -3,3 +3,4 @@
   <router-outlet></router-outlet>
 </main>
 <app-footer></app-footer>
+<app-toast></app-toast>

apps/frontend/src/app/app.ts

@@ -2,10 +2,11 @@ import { Component, inject, OnInit } from '@angular/core';
 import { RouterModule } from '@angular/router';
 import { HeaderComponent } from './components/header/header.component';
 import { FooterComponent } from './components/footer/footer.component';
+import { ToastComponent } from './components/toast/toast.component';
 import { AnalyticsService } from './services/analytics.service';
 
 @Component({
-  imports: [RouterModule, HeaderComponent, FooterComponent],
+  imports: [RouterModule, HeaderComponent, FooterComponent, ToastComponent],
   selector: 'app-root',
   templateUrl: './app.html',
   styleUrl: './app.scss',

apps/frontend/src/app/components/toast/toast.component.css

@@ -0,0 +1,91 @@
+/**
+ * @copyright 2026 NHCarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+.toast-container {
+  position: fixed;
+  top: 80px;
+  right: 20px;
+  z-index: 9999;
+  display: flex;
+  flex-direction: column;
+  gap: 10px;
+  max-width: 400px;
+}
+
+.toast {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  padding: 16px;
+  border-radius: 8px;
+  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
+  cursor: pointer;
+  animation: slideIn 0.3s ease-out;
+  border: 2px solid;
+  background-color: var(--witch-purple);
+  color: var(--moon-white);
+}
+
+.toast-error {
+  border-color: #ff4444;
+  background-color: rgba(255, 68, 68, 0.4);
+}
+
+.toast-success {
+  border-color: #44ff88;
+  background-color: rgba(68, 255, 136, 0.4);
+}
+
+.toast-info {
+  border-color: var(--witch-lavender);
+  background-color: rgba(200, 162, 200, 0.4);
+}
+
+.toast-warning {
+  border-color: #ffaa44;
+  background-color: rgba(255, 170, 68, 0.4);
+}
+
+.toast-icon {
+  font-size: 20px;
+  flex-shrink: 0;
+}
+
+.toast-message {
+  flex: 1;
+  word-wrap: break-word;
+}
+
+.toast-close {
+  background: none;
+  border: none;
+  color: var(--moon-white);
+  font-size: 24px;
+  cursor: pointer;
+  padding: 0;
+  width: 24px;
+  height: 24px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  flex-shrink: 0;
+  transition: transform 0.2s ease;
+}
+
+.toast-close:hover {
+  transform: scale(1.2);
+}
+
+@keyframes slideIn {
+  from {
+    transform: translateX(400px);
+    opacity: 0;
+  }
+  to {
+    transform: translateX(0);
+    opacity: 1;
+  }
+}

apps/frontend/src/app/components/toast/toast.component.html

@@ -0,0 +1,22 @@
+<!--
+  @copyright 2026 NHCarrigan
+  @license Naomi's Public License
+  @author Naomi Carrigan
+-->
+
+<div class="toast-container">
+  @for (toast of toastService.toastList(); track toast.id) {
+    <div class="toast toast-{{ toast.type }}" (click)="toastService.remove(toast.id)">
+      <div class="toast-icon">
+        @switch (toast.type) {
+          @case ('error') { ❌ }
+          @case ('success') { ✅ }
+          @case ('info') { ℹ️ }
+          @case ('warning') { ⚠️ }
+        }
+      </div>
+      <div class="toast-message">{{ toast.message }}</div>
+      <button class="toast-close" (click)="toastService.remove(toast.id)">×</button>
+    </div>
+  }
+</div>

apps/frontend/src/app/components/toast/toast.component.ts

@@ -0,0 +1,18 @@
+/**
+ * @copyright 2026 NHCarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+import { Component, inject } from '@angular/core';
+import { ToastService } from '../../services/toast.service';
+
+@Component({
+  selector: 'app-toast',
+  standalone: true,
+  templateUrl: './toast.component.html',
+  styleUrls: ['./toast.component.css']
+})
+export class ToastComponent {
+  public toastService = inject(ToastService);
+}

apps/frontend/src/app/interceptors/auth.interceptor.ts

@@ -16,11 +16,13 @@ import {
 import { Observable, catchError, throwError, switchMap, BehaviorSubject, filter, take } from 'rxjs';
 import { Router } from '@angular/router';
 import { environment } from '../../environments/environment';
+import { ToastService } from '../services/toast.service';
 
 @Injectable()
 export class AuthInterceptor implements HttpInterceptor {
   private router = inject(Router);
   private http = inject(HttpClient);
+  private toast = inject(ToastService);
 
   private isRefreshing = false;
   private refreshTokenSubject = new BehaviorSubject<boolean | null>(null);
@@ -36,6 +38,9 @@ export class AuthInterceptor implements HttpInterceptor {
         if (error.status === 401 && !request.url.includes('/auth/refresh') && !request.url.includes('/auth/logout')) {
           return this.handle401Error(authReq, next);
         }
+
+        // Show toast for other HTTP errors
+        this.showErrorToast(error);
         return throwError(() => error);
       })
     );
@@ -59,6 +64,7 @@ export class AuthInterceptor implements HttpInterceptor {
         catchError((err) => {
           this.isRefreshing = false;
           this.refreshTokenSubject.next(false);
+          this.toast.error('Your session has expired. Please log in again.');
           this.router.navigate(['/']);
           return throwError(() => err);
         })
@@ -76,4 +82,28 @@ export class AuthInterceptor implements HttpInterceptor {
       })
     );
   }
+
+  private showErrorToast(error: HttpErrorResponse): void {
+    let message = 'Something went wrong. Please try again.';
+
+    switch (error.status) {
+      case 400:
+        message = error.error?.message || 'Invalid request. Please check your input.';
+        break;
+      case 403:
+        message = 'You do not have permission to perform this action.';
+        break;
+      case 404:
+        message = 'Resource not found.';
+        break;
+      case 500:
+        message = 'Server error. Please try again later.';
+        break;
+      case 0:
+        message = 'Network error. Please check your connection.';
+        break;
+    }
+
+    this.toast.error(message);
+  }
 }

apps/frontend/src/app/services/global-error-handler.service.ts

@@ -0,0 +1,43 @@
+/**
+ * @copyright 2026 NHCarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+import { ErrorHandler, Injectable, inject } from '@angular/core';
+import { ToastService } from './toast.service';
+
+@Injectable()
+export class GlobalErrorHandler implements ErrorHandler {
+  private toast = inject(ToastService);
+
+  handleError(error: Error): void {
+    console.error('Global error caught:', error);
+
+    // Show user-friendly error message
+    const message = this.getUserFriendlyMessage(error);
+    this.toast.error(message);
+  }
+
+  private getUserFriendlyMessage(error: Error): string {
+    // Check for common error types
+    if (error.message.includes('Http failure')) {
+      return 'Network error. Please check your connection.';
+    }
+
+    if (error.message.includes('401') || error.message.includes('403')) {
+      return 'Your session has expired. Please refresh the page.';
+    }
+
+    if (error.message.includes('404')) {
+      return 'Resource not found.';
+    }
+
+    if (error.message.includes('500')) {
+      return 'Server error. Please try again later.';
+    }
+
+    // Generic error message
+    return 'Something went wrong. Please try again.';
+  }
+}

apps/frontend/src/app/services/toast.service.ts

@@ -0,0 +1,70 @@
+/**
+ * @copyright 2026 NHCarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+import { Injectable, signal } from '@angular/core';
+
+export interface Toast {
+  id: number;
+  message: string;
+  type: 'error' | 'success' | 'info' | 'warning';
+  duration: number;
+}
+
+@Injectable({
+  providedIn: 'root'
+})
+export class ToastService {
+  private toasts = signal<Toast[]>([]);
+  public readonly toastList = this.toasts.asReadonly();
+  private nextId = 0;
+
+  /**
+   * Show an error toast notification.
+   */
+  error(message: string, duration = 5000): void {
+    this.addToast(message, 'error', duration);
+  }
+
+  /**
+   * Show a success toast notification.
+   */
+  success(message: string, duration = 3000): void {
+    this.addToast(message, 'success', duration);
+  }
+
+  /**
+   * Show an info toast notification.
+   */
+  info(message: string, duration = 3000): void {
+    this.addToast(message, 'info', duration);
+  }
+
+  /**
+   * Show a warning toast notification.
+   */
+  warning(message: string, duration = 4000): void {
+    this.addToast(message, 'warning', duration);
+  }
+
+  /**
+   * Remove a toast by ID.
+   */
+  remove(id: number): void {
+    this.toasts.update(toasts => toasts.filter(t => t.id !== id));
+  }
+
+  private addToast(message: string, type: Toast['type'], duration: number): void {
+    const id = this.nextId++;
+    const toast: Toast = { id, message, type, duration };
+
+    this.toasts.update(toasts => [...toasts, toast]);
+
+    // Auto-remove after duration
+    setTimeout(() => {
+      this.remove(id);
+    }, duration);
+  }
+}