diff --git a/apps/calendar/apps/web/src/routes/+layout.svelte b/apps/calendar/apps/web/src/routes/+layout.svelte
index fcbf8de56..72bb7bc61 100644
--- a/apps/calendar/apps/web/src/routes/+layout.svelte
+++ b/apps/calendar/apps/web/src/routes/+layout.svelte
@@ -3,7 +3,7 @@
 	import '$lib/i18n';
 	import { theme } from '$lib/stores/theme';
 	import { authStore } from '$lib/stores/auth.svelte';
-	import { ToastContainer } from '@manacore/shared-ui';
+	import { ToastContainer, setupGlobalErrorHandler } from '@manacore/shared-ui';
 	import { AppLoadingSkeleton } from '$lib/components/skeletons';
 	import { isLoading as i18nLoading } from 'svelte-i18n';
 	import { onMount } from 'svelte';
@@ -13,10 +13,16 @@
 	let loading = $state(true);
 	let appReady = $derived(!loading && !$i18nLoading);
 
-	onMount(async () => {
+	onMount(() => {
+		// Setup global error handling
+		const cleanupErrorHandler = setupGlobalErrorHandler();
+
 		theme.initialize();
-		await authStore.initialize();
-		loading = false;
+		authStore.initialize().then(() => {
+			loading = false;
+		});
+
+		return cleanupErrorHandler;
 	});
 </script>
 
diff --git a/apps/chat/apps/web/src/routes/+layout.svelte b/apps/chat/apps/web/src/routes/+layout.svelte
index 1e6853364..2c89e2faf 100644
--- a/apps/chat/apps/web/src/routes/+layout.svelte
+++ b/apps/chat/apps/web/src/routes/+layout.svelte
@@ -2,13 +2,18 @@
 	import '../app.css';
 	import { onMount } from 'svelte';
 	import { theme } from '$lib/stores/theme';
-	import { ToastContainer } from '@manacore/shared-ui';
+	import { ToastContainer, setupGlobalErrorHandler } from '@manacore/shared-ui';
 
 	let { children } = $props();
 
 	onMount(() => {
-		const cleanup = theme.initialize();
-		return cleanup;
+		const cleanupErrorHandler = setupGlobalErrorHandler();
+		const cleanupTheme = theme.initialize();
+
+		return () => {
+			cleanupErrorHandler();
+			cleanupTheme();
+		};
 	});
 </script>
 
diff --git a/apps/clock/apps/web/src/routes/+layout.svelte b/apps/clock/apps/web/src/routes/+layout.svelte
index ceaec48ce..489b4af31 100644
--- a/apps/clock/apps/web/src/routes/+layout.svelte
+++ b/apps/clock/apps/web/src/routes/+layout.svelte
@@ -5,24 +5,34 @@
 	import { theme } from '$lib/stores/theme.svelte';
 	import { authStore } from '$lib/stores/auth.svelte';
 	import { waitLocale } from '$lib/i18n';
-	import { ToastContainer } from '@manacore/shared-ui';
+	import { ToastContainer, setupGlobalErrorHandler } from '@manacore/shared-ui';
 	import { AppLoadingSkeleton } from '$lib/components/skeletons';
 
 	let { children } = $props();
 
 	let loading = $state(true);
 
-	onMount(async () => {
-		// Wait for locale to be loaded
-		await waitLocale();
+	onMount(() => {
+		// Setup global error handling
+		const cleanupErrorHandler = setupGlobalErrorHandler();
 
-		// Initialize theme
-		theme.initialize();
+		// Initialize async operations
+		const init = async () => {
+			// Wait for locale to be loaded
+			await waitLocale();
 
-		// Initialize auth
-		await authStore.initialize();
+			// Initialize theme
+			theme.initialize();
 
-		loading = false;
+			// Initialize auth
+			await authStore.initialize();
+
+			loading = false;
+		};
+
+		init();
+
+		return cleanupErrorHandler;
 	});
 </script>
 
diff --git a/apps/contacts/apps/web/src/routes/+layout.svelte b/apps/contacts/apps/web/src/routes/+layout.svelte
index 35cbef0d2..ef2718de6 100644
--- a/apps/contacts/apps/web/src/routes/+layout.svelte
+++ b/apps/contacts/apps/web/src/routes/+layout.svelte
@@ -2,11 +2,10 @@
 	import '../app.css';
 	import '$lib/i18n'; // Initialize i18n early
 	import { onMount } from 'svelte';
-	import { browser } from '$app/environment';
 	import { isLoading as i18nLoading } from 'svelte-i18n';
 	import { theme } from '$lib/stores/theme';
 	import { authStore } from '$lib/stores/auth.svelte';
-	import { toastStore, ToastContainer } from '@manacore/shared-ui';
+	import { ToastContainer, setupGlobalErrorHandler } from '@manacore/shared-ui';
 	import { AppLoadingSkeleton } from '$lib/components/skeletons';
 
 	let { children } = $props();
@@ -16,73 +15,19 @@
 	// Derived state: app is ready when auth is initialized AND i18n is loaded
 	let appReady = $derived(!loading && !$i18nLoading);
 
-	/**
-	 * Global error handler for unhandled promise rejections and API errors
-	 */
-	function setupGlobalErrorHandling() {
-		if (!browser) return;
-
-		// Handle unhandled promise rejections (e.g., failed API calls)
-		window.addEventListener('unhandledrejection', (event) => {
-			const error = event.reason;
-
-			// Extract error message
-			let message = 'Ein unerwarteter Fehler ist aufgetreten';
-
-			if (error instanceof Error) {
-				// Network errors
-				if (error.message === 'Failed to fetch' || error.name === 'TypeError') {
-					message = 'Netzwerkfehler: Server nicht erreichbar';
-				}
-				// Auth errors
-				else if (
-					error.message.includes('401') ||
-					error.message.toLowerCase().includes('unauthorized')
-				) {
-					message = 'Sitzung abgelaufen. Bitte erneut anmelden.';
-				}
-				// Other API errors
-				else if (error.message) {
-					message = error.message;
-				}
-			}
-
-			// Show toast notification
-			toastStore.error(message);
-
-			// Prevent default browser error handling
-			event.preventDefault();
-		});
-
-		// Handle general JavaScript errors
-		window.addEventListener('error', (event) => {
-			// Only handle non-script errors (network failures for resources, etc.)
-			if (event.message && !event.filename) {
-				toastStore.error('Ein Fehler ist aufgetreten');
-			}
-		});
-
-		// Handle offline/online status
-		window.addEventListener('offline', () => {
-			toastStore.warning('Keine Internetverbindung', 10000);
-		});
-
-		window.addEventListener('online', () => {
-			toastStore.success('Verbindung wiederhergestellt');
-		});
-	}
-
-	onMount(async () => {
-		// Setup global error handling
-		setupGlobalErrorHandling();
+	onMount(() => {
+		// Setup global error handling (German translations by default)
+		const cleanupErrorHandler = setupGlobalErrorHandler();
 
 		// Initialize theme
 		theme.initialize();
 
 		// Initialize auth
-		await authStore.initialize();
+		authStore.initialize().then(() => {
+			loading = false;
+		});
 
-		loading = false;
+		return cleanupErrorHandler;
 	});
 </script>
 
diff --git a/apps/matrix/apps/web/src/routes/+layout.svelte b/apps/matrix/apps/web/src/routes/+layout.svelte
index 44996b54e..fd716edc6 100644
--- a/apps/matrix/apps/web/src/routes/+layout.svelte
+++ b/apps/matrix/apps/web/src/routes/+layout.svelte
@@ -5,7 +5,7 @@
 	import type { Snippet } from 'svelte';
 	import { isLoading as i18nLoading, _ as t } from 'svelte-i18n';
 	import { theme } from '$lib/stores/theme';
-	import { ToastContainer } from '@manacore/shared-ui';
+	import { ToastContainer, setupGlobalErrorHandler } from '@manacore/shared-ui';
 
 	interface Props {
 		children: Snippet;
@@ -14,8 +14,13 @@
 	let { children }: Props = $props();
 
 	onMount(() => {
-		const cleanup = theme.initialize();
-		return cleanup;
+		const cleanupErrorHandler = setupGlobalErrorHandler();
+		const cleanupTheme = theme.initialize();
+
+		return () => {
+			cleanupErrorHandler();
+			cleanupTheme();
+		};
 	});
 </script>
 
diff --git a/apps/picture/apps/web/src/routes/+layout.svelte b/apps/picture/apps/web/src/routes/+layout.svelte
index 10de2e8ec..eece69687 100644
--- a/apps/picture/apps/web/src/routes/+layout.svelte
+++ b/apps/picture/apps/web/src/routes/+layout.svelte
@@ -2,7 +2,7 @@
 	import '../app.css';
 	import favicon from '$lib/assets/favicon.svg';
 	import { authStore } from '$lib/stores/auth.svelte';
-	import { ToastContainer } from '@manacore/shared-ui';
+	import { ToastContainer, setupGlobalErrorHandler } from '@manacore/shared-ui';
 	import { onMount } from 'svelte';
 
 	// Import and initialize theme
@@ -14,6 +14,9 @@
 	let { children, data } = $props();
 
 	onMount(() => {
+		// Setup global error handling
+		const cleanupErrorHandler = setupGlobalErrorHandler();
+
 		// Initialize theme (applies CSS variables and loads from localStorage)
 		const cleanupTheme = theme.initialize();
 
@@ -21,6 +24,7 @@
 		authStore.initialize();
 
 		return () => {
+			cleanupErrorHandler();
 			cleanupTheme();
 		};
 	});
diff --git a/apps/storage/apps/web/src/routes/+layout.svelte b/apps/storage/apps/web/src/routes/+layout.svelte
index 96addf775..41d8e1439 100644
--- a/apps/storage/apps/web/src/routes/+layout.svelte
+++ b/apps/storage/apps/web/src/routes/+layout.svelte
@@ -3,7 +3,7 @@
 	import { page } from '$app/stores';
 	import { onMount } from 'svelte';
 	import { locale } from 'svelte-i18n';
-	import { PillNavigation } from '@manacore/shared-ui';
+	import { PillNavigation, setupGlobalErrorHandler } from '@manacore/shared-ui';
 	import type { PillNavItem, PillDropdownItem } from '@manacore/shared-ui';
 	import { theme } from '$lib/stores/theme.svelte';
 	import { authStore } from '$lib/stores/auth.svelte';
@@ -140,31 +140,41 @@
 		goto('/login');
 	}
 
-	onMount(async () => {
-		// Initialize theme
-		theme.initialize();
+	onMount(() => {
+		// Setup global error handling
+		const cleanupErrorHandler = setupGlobalErrorHandler();
 
-		// Initialize auth
-		await authStore.initialize();
+		// Initialize async operations
+		const init = async () => {
+			// Initialize theme
+			theme.initialize();
 
-		// Load user settings
-		await userSettings.load();
+			// Initialize auth
+			await authStore.initialize();
 
-		// Initialize sidebar mode from localStorage
-		const savedSidebar = localStorage.getItem('storage-nav-sidebar');
-		if (savedSidebar === 'true') {
-			isSidebarMode = true;
-			sidebarModeStore.set(true);
-		}
+			// Load user settings
+			await userSettings.load();
 
-		// Initialize collapsed state from localStorage
-		const savedCollapsed = localStorage.getItem('storage-nav-collapsed');
-		if (savedCollapsed === 'true') {
-			isCollapsed = true;
-			collapsedStore.set(true);
-		}
+			// Initialize sidebar mode from localStorage
+			const savedSidebar = localStorage.getItem('storage-nav-sidebar');
+			if (savedSidebar === 'true') {
+				isSidebarMode = true;
+				sidebarModeStore.set(true);
+			}
 
-		loading = false;
+			// Initialize collapsed state from localStorage
+			const savedCollapsed = localStorage.getItem('storage-nav-collapsed');
+			if (savedCollapsed === 'true') {
+				isCollapsed = true;
+				collapsedStore.set(true);
+			}
+
+			loading = false;
+		};
+
+		init();
+
+		return cleanupErrorHandler;
 	});
 </script>
 
diff --git a/docs/CONSISTENCY_REPORT.md b/docs/CONSISTENCY_REPORT.md
index ca2bf53d0..cbb8b9adc 100644
--- a/docs/CONSISTENCY_REPORT.md
+++ b/docs/CONSISTENCY_REPORT.md
@@ -26,6 +26,7 @@ Nach eingehender Analyse aller Web-Apps im Monorepo wurden folgende Bereiche auf
 5. ✅ **@manacore/shared-api-client Package erstellt** - 10 Apps migriert (clock, todo, contacts, storage, calendar, picture, nutriphi, planta, questions, skilltree)
 6. ✅ **i18n zu 6 Apps hinzugefügt** - todo, skilltree, nutriphi, planta, questions, matrix (jeweils DE + EN)
 7. ✅ **AuthGateModal zentralisiert** - `@manacore/shared-auth-ui` für 4 Apps (chat, todo, contacts, calendar)
+8. ✅ **Global Error Handler zentralisiert** - `@manacore/shared-ui` für 7 Apps (calendar, chat, clock, contacts, matrix, picture, storage)
 
 ---
 
@@ -220,18 +221,24 @@ Alle Apps nutzen **Mana Core Auth** mit `@manacore/shared-auth`.
 - Jede App hat eigene Version
 - Könnte mit `@manacore/shared-ui` Skeletons vereinheitlicht werden
 
-#### Global Error Handler
+#### Global Error Handler ✅
 
-- Nur in Contacts App vollständig implementiert
-- Sollte extrahiert werden
+> **Status: Erledigt (29.01.2026)**
+
+- ✅ Zentraler Global Error Handler in `@manacore/shared-ui`
+- ✅ Migrierte Apps: calendar, chat, clock, contacts, matrix, picture, storage
+- Funktion: `setupGlobalErrorHandler(options?)`
+- Behandelt: Unhandled Promise Rejections, JS Errors, Offline/Online Status
+- i18n: DE + EN eingebaut, erweiterbar
+- Optional: `onAuthError` Callback für Redirect
 
 ### Empfehlungen (nach Priorität)
 
 #### Hoch
 
-1. **Toast Store & Component vereinheitlichen** - Svelte 5 Runes Standard
-2. **AuthGateModal nach shared-auth-ui** verschieben
-3. **Global Error Handler** als Composable extrahieren
+1. ~~**Toast Store & Component vereinheitlichen**~~ ✅ Erledigt
+2. ~~**AuthGateModal nach shared-auth-ui**~~ ✅ Erledigt
+3. ~~**Global Error Handler**~~ ✅ Erledigt
 
 #### Mittel
 
@@ -254,6 +261,7 @@ Alle Apps nutzen **Mana Core Auth** mit `@manacore/shared-auth`.
 | ~~API Client Package erstellen~~ | ✅ Erledigt (10 Apps migriert) |
 | ~~i18n zu 6 Apps hinzufügen~~ | ✅ Erledigt |
 | ~~AuthGateModal zentralisieren~~ | ✅ Erledigt (4 Apps migriert) |
+| ~~Global Error Handler extrahieren~~ | ✅ Erledigt (7 Apps migriert) |
 
 ### 🔴 Hohe Priorität
 
@@ -261,10 +269,7 @@ _(Keine offenen Aufgaben mit hoher Priorität)_
 
 ### 🟡 Mittlere Priorität
 
-| Aufgabe | Aufwand | Impact |
-|---------|---------|--------|
-| ~~AuthGateModal in Shared Package~~ | ~~Niedrig~~ | ✅ Erledigt |
-| Global Error Handler extrahieren | Niedrig | Error UX |
+_(Keine offenen Aufgaben mit mittlerer Priorität)_
 
 ### 🟢 Niedrige Priorität
 
@@ -280,8 +285,9 @@ _(Keine offenen Aufgaben mit hoher Priorität)_
 1. ~~**API Client Package** als nächstes angehen (höchster Impact)~~ ✅ Erledigt
 2. ~~**i18n** zu fehlenden Apps hinzufügen~~ ✅ Erledigt (6 Apps)
 3. ~~**AuthGateModal** in Shared Package extrahieren~~ ✅ Erledigt (4 Apps)
-4. **Global Error Handler** extrahieren
-5. Schrittweise weitere Punkte abarbeiten
+4. ~~**Global Error Handler** extrahieren~~ ✅ Erledigt (7 Apps)
+5. **App-Skeletons vereinheitlichen** (niedrige Priorität)
+6. **Auth Store Pattern dokumentieren** (niedrige Priorität)
 
 ---
 
diff --git a/packages/shared-ui/src/index.ts b/packages/shared-ui/src/index.ts
index 319814da4..8ba5222d4 100644
--- a/packages/shared-ui/src/index.ts
+++ b/packages/shared-ui/src/index.ts
@@ -196,6 +196,18 @@ export type {
 // Immersive Mode
 export { default as ImmersiveModeToggle } from './components/ImmersiveModeToggle.svelte';
 
-// Toast
-export { toastStore, toast, handleApiError, ToastContainer } from './toast';
-export type { Toast, ToastType } from './toast';
+// Toast & Global Error Handling
+export {
+	toastStore,
+	toast,
+	handleApiError,
+	ToastContainer,
+	setupGlobalErrorHandler,
+	GLOBAL_ERROR_TRANSLATIONS,
+} from './toast';
+export type {
+	Toast,
+	ToastType,
+	GlobalErrorHandlerOptions,
+	GlobalErrorHandlerTranslations,
+} from './toast';
diff --git a/packages/shared-ui/src/toast/globalErrorHandler.ts b/packages/shared-ui/src/toast/globalErrorHandler.ts
new file mode 100644
index 000000000..af8977ea2
--- /dev/null
+++ b/packages/shared-ui/src/toast/globalErrorHandler.ts
@@ -0,0 +1,180 @@
+/**
+ * Global Error Handler - Catches unhandled errors and shows toast notifications
+ *
+ * Usage:
+ * ```ts
+ * import { setupGlobalErrorHandler } from '@manacore/shared-ui';
+ * import { onMount } from 'svelte';
+ *
+ * onMount(() => {
+ *   const cleanup = setupGlobalErrorHandler();
+ *   return cleanup; // Optional: cleanup on unmount
+ * });
+ *
+ * // With custom translations:
+ * setupGlobalErrorHandler({
+ *   networkError: 'Network error: Server unreachable',
+ *   sessionExpired: 'Session expired. Please log in again.',
+ *   unexpectedError: 'An unexpected error occurred',
+ *   genericError: 'An error occurred',
+ *   offline: 'No internet connection',
+ *   online: 'Connection restored',
+ * });
+ * ```
+ */
+
+import { toastStore } from './toast.svelte';
+
+export interface GlobalErrorHandlerTranslations {
+	/** Message for network/fetch errors */
+	networkError: string;
+	/** Message for 401/unauthorized errors */
+	sessionExpired: string;
+	/** Fallback message for unhandled promise rejections */
+	unexpectedError: string;
+	/** Message for general JavaScript errors */
+	genericError: string;
+	/** Message when going offline */
+	offline: string;
+	/** Message when connection is restored */
+	online: string;
+}
+
+const DEFAULT_TRANSLATIONS_DE: GlobalErrorHandlerTranslations = {
+	networkError: 'Netzwerkfehler: Server nicht erreichbar',
+	sessionExpired: 'Sitzung abgelaufen. Bitte erneut anmelden.',
+	unexpectedError: 'Ein unerwarteter Fehler ist aufgetreten',
+	genericError: 'Ein Fehler ist aufgetreten',
+	offline: 'Keine Internetverbindung',
+	online: 'Verbindung wiederhergestellt',
+};
+
+const DEFAULT_TRANSLATIONS_EN: GlobalErrorHandlerTranslations = {
+	networkError: 'Network error: Server unreachable',
+	sessionExpired: 'Session expired. Please log in again.',
+	unexpectedError: 'An unexpected error occurred',
+	genericError: 'An error occurred',
+	offline: 'No internet connection',
+	online: 'Connection restored',
+};
+
+export const GLOBAL_ERROR_TRANSLATIONS = {
+	de: DEFAULT_TRANSLATIONS_DE,
+	en: DEFAULT_TRANSLATIONS_EN,
+} as const;
+
+export interface GlobalErrorHandlerOptions {
+	/** Custom translations (default: German) */
+	translations?: Partial<GlobalErrorHandlerTranslations>;
+	/** Locale key to use built-in translations (overridden by translations if provided) */
+	locale?: 'de' | 'en';
+	/** Duration for offline warning toast in ms (default: 10000) */
+	offlineDuration?: number;
+	/** Enable console logging for debugging (default: false) */
+	debug?: boolean;
+	/** Custom handler for auth errors (e.g., redirect to login) */
+	onAuthError?: () => void;
+}
+
+/**
+ * Sets up global error handling for unhandled promise rejections,
+ * JavaScript errors, and network connectivity changes.
+ *
+ * @param options - Configuration options
+ * @returns Cleanup function to remove event listeners
+ */
+export function setupGlobalErrorHandler(options: GlobalErrorHandlerOptions = {}): () => void {
+	// Don't run on server
+	if (typeof window === 'undefined') {
+		return () => {};
+	}
+
+	const {
+		translations: customTranslations,
+		locale = 'de',
+		offlineDuration = 10000,
+		debug = false,
+		onAuthError,
+	} = options;
+
+	// Merge built-in translations with custom overrides
+	const baseTranslations = GLOBAL_ERROR_TRANSLATIONS[locale] || DEFAULT_TRANSLATIONS_DE;
+	const translations: GlobalErrorHandlerTranslations = {
+		...baseTranslations,
+		...customTranslations,
+	};
+
+	const log = (msg: string, ...args: unknown[]) => {
+		if (debug) {
+			console.log(`[GlobalErrorHandler] ${msg}`, ...args);
+		}
+	};
+
+	// Handle unhandled promise rejections
+	const handleUnhandledRejection = (event: PromiseRejectionEvent) => {
+		const error = event.reason;
+		log('Unhandled rejection:', error);
+
+		let message = translations.unexpectedError;
+
+		if (error instanceof Error) {
+			// Network errors
+			if (error.message === 'Failed to fetch' || error.name === 'TypeError') {
+				message = translations.networkError;
+			}
+			// Auth errors
+			else if (
+				error.message.includes('401') ||
+				error.message.toLowerCase().includes('unauthorized')
+			) {
+				message = translations.sessionExpired;
+				onAuthError?.();
+			}
+			// Other errors with messages
+			else if (error.message) {
+				message = error.message;
+			}
+		}
+
+		toastStore.error(message);
+		event.preventDefault();
+	};
+
+	// Handle general JavaScript errors
+	const handleError = (event: ErrorEvent) => {
+		log('Error event:', event);
+		// Only handle non-script errors (network failures for resources, etc.)
+		if (event.message && !event.filename) {
+			toastStore.error(translations.genericError);
+		}
+	};
+
+	// Handle offline status
+	const handleOffline = () => {
+		log('Offline');
+		toastStore.warning(translations.offline, offlineDuration);
+	};
+
+	// Handle online status
+	const handleOnline = () => {
+		log('Online');
+		toastStore.success(translations.online);
+	};
+
+	// Add event listeners
+	window.addEventListener('unhandledrejection', handleUnhandledRejection);
+	window.addEventListener('error', handleError);
+	window.addEventListener('offline', handleOffline);
+	window.addEventListener('online', handleOnline);
+
+	log('Initialized');
+
+	// Return cleanup function
+	return () => {
+		window.removeEventListener('unhandledrejection', handleUnhandledRejection);
+		window.removeEventListener('error', handleError);
+		window.removeEventListener('offline', handleOffline);
+		window.removeEventListener('online', handleOnline);
+		log('Cleaned up');
+	};
+}
diff --git a/packages/shared-ui/src/toast/index.ts b/packages/shared-ui/src/toast/index.ts
index 67db8c244..6b262098f 100644
--- a/packages/shared-ui/src/toast/index.ts
+++ b/packages/shared-ui/src/toast/index.ts
@@ -1,3 +1,8 @@
 export { toastStore, toast, handleApiError } from './toast.svelte';
 export type { Toast, ToastType } from './toast.svelte';
 export { default as ToastContainer } from './ToastContainer.svelte';
+export { setupGlobalErrorHandler, GLOBAL_ERROR_TRANSLATIONS } from './globalErrorHandler';
+export type {
+	GlobalErrorHandlerOptions,
+	GlobalErrorHandlerTranslations,
+} from './globalErrorHandler';