diff --git a/ts/AppSync.vue b/ts/AppSync.vue
index f6833fa5..1e68fc5f 100644
--- a/ts/AppSync.vue
+++ b/ts/AppSync.vue
@@ -1,14 +1,50 @@
+<style>
+.global-error-toast {
+	position: fixed;
+	top: 20px;
+	right: 20px;
+	background: #c00;
+	color: white;
+	padding: 16px 20px;
+	border-radius: 8px;
+	box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
+	z-index: 9999;
+	max-width: 400px;
+	animation: slideIn 0.3s ease;
+}
+
+@keyframes slideIn {
+	from {
+		transform: translateX(400px);
+		opacity: 0;
+	}
+	to {
+		transform: translateX(0);
+		opacity: 1;
+	}
+}
+</style>
+
 <template>
-	<router-view />
+	<div id="app">
+		<div v-if="error" class="global-error-toast">
+			{{ error.message }}
+			<button @click="errorClear">x</button>
+		</div>
+		<router-view />
+	</div>
 </template>
 
 <script setup lang="ts">
 import { onMounted } from "vue";
 import { apiClient } from "@/client";
 import router from "@/route/config";
+import { useErrorHandler } from "@/composable/error-handler";
 
 import { SSEManager, type SSEMessageResource } from "@/SSEManager";
 
+const { error, errorClear } = useErrorHandler();
+
 onMounted(() => {
 	SSEManager.connect("/api/events");
 	SSEManager.subscribe((msg: SSEMessageResource) => {
diff --git a/ts/composable/error-handler.ts b/ts/composable/error-handler.ts
new file mode 100644
index 00000000..30080a18
--- /dev/null
+++ b/ts/composable/error-handler.ts
@@ -0,0 +1,29 @@
+import { ref } from "vue";
+
+interface ErrorState {
+	hasError: boolean;
+	message: string;
+	timestamp: Date;
+}
+
+const globalError = ref<ErrorState | null>(null);
+
+export function useErrorHandler() {
+	const setError = (error: Error) => {
+		globalError.value = {
+			hasError: true,
+			message: error.message,
+			timestamp: new Date(),
+		};
+	};
+
+	const errorClear = () => {
+		globalError.value = null;
+	};
+
+	return {
+		error: globalError,
+		setError,
+		errorClear,
+	};
+}
diff --git a/vite/sync/main.ts b/vite/sync/main.ts
index 87c11b76..cef6be45 100644
--- a/vite/sync/main.ts
+++ b/vite/sync/main.ts
@@ -4,6 +4,7 @@ import App from "@/AppSync.vue";
 import * as config from "@/config";
 import router from "@/route/config";
 import * as sentry from "@/sentry";
+import { useErrorHandler } from "@/composable/error-handler";
 
 import "maplibre-gl/dist/maplibre-gl.css";
 
@@ -18,8 +19,24 @@ import "@/gen/custom-icons.scss";
 import * as bootstrap from "bootstrap";
 window.bootstrap = bootstrap;
 
+const { setError } = useErrorHandler();
+
 const pinia = createPinia();
 const app = createApp(App);
+app.config.errorHandler = (err, instance, info) => {
+	// err: the error object
+	// instance: the component instance where error occurred
+	// info: Vue-specific error info, e.g., lifecycle hook
+
+	console.error("Global error:", err);
+	console.error("Error info:", info);
+	console.error("Error instance:", instance);
+
+	// You could dispatch to a store, send to error tracking service, etc.
+	// For example, trigger a global error state
+	setError(err);
+};
+
 app.use(pinia);
 app.use(router);
 sentry.Init(app, pinia).then(() => {