diff --git a/package-lock.json b/package-lock.json
index dbfcfe7..fec8202 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -61,7 +61,7 @@
         "tailwind-merge": "^2.5.2",
         "tailwindcss-animate": "^1.0.7",
         "vaul": "^0.9.3",
-        "zod": "^3.23.8"
+        "zod": "^3.25.71"
       },
       "devDependencies": {
         "@eslint/js": "^9.9.0",
@@ -8244,9 +8244,9 @@
       }
     },
     "node_modules/zod": {
-      "version": "3.24.3",
-      "resolved": "https://registry.npmjs.org/zod/-/zod-3.24.3.tgz",
-      "integrity": "sha512-HhY1oqzWCQWuUqvBFnsyrtZRhyPeR7SUGv+C4+MsisMuVfSPx8HpwWqH8tRahSlt6M3PiFAcoeFhZAqIXTxoSg==",
+      "version": "3.25.71",
+      "resolved": "https://registry.npmjs.org/zod/-/zod-3.25.71.tgz",
+      "integrity": "sha512-BsBc/NPk7h8WsUWYWYL+BajcJPY8YhjelaWu2NMLuzgraKAz4Lb4/6K11g9jpuDetjMiqhZ6YaexFLOC0Ogi3Q==",
       "license": "MIT",
       "funding": {
         "url": "https://github.com/sponsors/colinhacks"
diff --git a/package.json b/package.json
index eefa69c..94d0460 100644
--- a/package.json
+++ b/package.json
@@ -63,7 +63,7 @@
     "tailwind-merge": "^2.5.2",
     "tailwindcss-animate": "^1.0.7",
     "vaul": "^0.9.3",
-    "zod": "^3.23.8"
+    "zod": "^3.25.71"
   },
   "devDependencies": {
     "@eslint/js": "^9.9.0",
diff --git a/src/components/AppProvider.tsx b/src/components/AppProvider.tsx
index d571e24..ebbbbe4 100644
--- a/src/components/AppProvider.tsx
+++ b/src/components/AppProvider.tsx
@@ -1,4 +1,5 @@
 import { ReactNode, useEffect } from 'react';
+import { z } from 'zod';
 import { useLocalStorage } from '@/hooks/useLocalStorage';
 import { AppContext, type AppConfig, type AppContextType, type Theme } from '@/contexts/AppContext';
 
@@ -12,6 +13,12 @@ interface AppProviderProps {
   presetRelays?: { name: string; url: string }[];
 }
 
+// Zod schema for AppConfig validation
+const AppConfigSchema: z.ZodType<AppConfig> = z.object({
+  theme: z.enum(['dark', 'light', 'system']),
+  relayUrl: z.string().url(),
+});
+
 export function AppProvider(props: AppProviderProps) {
   const {
     children,
@@ -21,7 +28,17 @@ export function AppProvider(props: AppProviderProps) {
   } = props;
 
   // App configuration state with localStorage persistence
-  const [config, setConfig] = useLocalStorage<AppConfig>(storageKey, defaultConfig);
+  const [config, setConfig] = useLocalStorage<AppConfig>(
+    storageKey,
+    defaultConfig,
+    {
+      serialize: JSON.stringify,
+      deserialize: (value: string) => {
+        const parsed = JSON.parse(value);
+        return AppConfigSchema.parse(parsed);
+      }
+    }
+  );
 
   // Generic config updater with callback pattern
   const updateConfig = (updater: (currentConfig: AppConfig) => AppConfig) => {