diff --git a/packages/mobile/src/constants/theme.ts b/packages/mobile/src/constants/theme.ts
index c661414..9748830 100644
--- a/packages/mobile/src/constants/theme.ts
+++ b/packages/mobile/src/constants/theme.ts
@@ -52,6 +52,8 @@ export const SHADOWS = {
 
 export const API_URL = process.env.EXPO_PUBLIC_API_URL || 'https://api.shieldai.freno.me/api/v1';
 
+export const EAS_PROJECT_ID = process.env.EXPO_PUBLIC_EAS_PROJECT_ID || '';
+
 export const getSeverityColor = (severity: string): string => {
   switch (severity) {
     case 'critical': return COLORS.danger;
diff --git a/packages/mobile/src/hooks/useBiometricAuth.ts b/packages/mobile/src/hooks/useBiometricAuth.ts
index 501f23e..b1ba01e 100644
--- a/packages/mobile/src/hooks/useBiometricAuth.ts
+++ b/packages/mobile/src/hooks/useBiometricAuth.ts
@@ -1,24 +1,42 @@
-import { useCallback } from 'react';
+import { useCallback, useState, useEffect } from 'react';
 import * as LocalAuthentication from 'expo-local-authentication';
+import { Alert } from 'react-native';
 import { useSettingsStore } from '@/store/settingsStore';
 
 export function useBiometricAuth() {
   const { isBiometricEnabled } = useSettingsStore();
+  const [biometricsAvailable, setBiometricsAvailable] = useState(false);
+
+  useEffect(() => {
+    (async () => {
+      const hasHardware = await LocalAuthentication.hasHardwareAsync();
+      const isEnrolled = await LocalAuthentication.isEnrolledAsync();
+      setBiometricsAvailable(hasHardware && isEnrolled);
+    })();
+  }, []);
 
   const authenticate = useCallback(async (): Promise<boolean> => {
     if (!isBiometricEnabled) return true;
 
     try {
       const isAvailable = await LocalAuthentication.hasHardwareAsync();
-      if (!isAvailable) return true;
-
       const isEnrolled = await LocalAuthentication.isEnrolledAsync();
-      if (!isEnrolled) return true;
+
+      if (!isAvailable || !isEnrolled) {
+        Alert.alert(
+          'Biometric Unavailable',
+          'Biometric authentication requires hardware and enrollment. Please use your password.',
+          [{ text: 'OK' }]
+        );
+        useSettingsStore.getState().toggleBiometric(false);
+        return false;
+      }
 
       const result = await LocalAuthentication.authenticateAsync({
         promptMessage: 'Authenticate with biometrics',
         fallbackLabel: 'Use passcode',
         cancelLabel: 'Cancel',
+        disableDeviceFallback: false,
       });
 
       return result.success;
@@ -31,7 +49,14 @@ export function useBiometricAuth() {
     const isAvailable = await LocalAuthentication.hasHardwareAsync();
     const isEnrolled = await LocalAuthentication.isEnrolledAsync();
 
-    if (!isAvailable || !isEnrolled) return false;
+    if (!isAvailable || !isEnrolled) {
+      Alert.alert(
+        'Biometric Not Available',
+        'Your device does not support biometric authentication or no credentials are enrolled.',
+        [{ text: 'OK' }]
+      );
+      return false;
+    }
 
     const result = await LocalAuthentication.authenticateAsync({
       promptMessage: 'Enable biometric authentication',
@@ -49,5 +74,5 @@ export function useBiometricAuth() {
     useSettingsStore.getState().toggleBiometric(false);
   }, []);
 
-  return { authenticate, enableBiometric, disableBiometric, isBiometricEnabled };
+  return { authenticate, enableBiometric, disableBiometric, isBiometricEnabled, biometricsAvailable };
 }
diff --git a/packages/mobile/src/hooks/usePushNotifications.ts b/packages/mobile/src/hooks/usePushNotifications.ts
index 07bd8c9..96a4692 100644
--- a/packages/mobile/src/hooks/usePushNotifications.ts
+++ b/packages/mobile/src/hooks/usePushNotifications.ts
@@ -4,6 +4,7 @@ import { Platform } from 'react-native';
 import * as Device from 'expo-device';
 import { deviceService, notificationService } from '@shieldai/mobile-api-client';
 import { useSettingsStore } from '@/store/settingsStore';
+import { EAS_PROJECT_ID } from '@/constants/theme';
 
 export function usePushNotifications() {
   const preferencesRef = useRef(useSettingsStore.getState().preferences);
@@ -40,8 +41,13 @@ export function usePushNotifications() {
         return null;
       }
 
+      if (!EAS_PROJECT_ID) {
+        console.warn('EAS_PROJECT_ID not configured — push notifications disabled');
+        return null;
+      }
+
       const token = (await Notifications.getExpoPushTokenAsync({
-        projectId: 'shieldai-project-id',
+        projectId: EAS_PROJECT_ID,
       })).data;
 
       try {
diff --git a/packages/mobile/src/screens/auth/LoginScreen.tsx b/packages/mobile/src/screens/auth/LoginScreen.tsx
index d71b861..bfdde75 100644
--- a/packages/mobile/src/screens/auth/LoginScreen.tsx
+++ b/packages/mobile/src/screens/auth/LoginScreen.tsx
@@ -1,5 +1,6 @@
 import React, { useState } from 'react';
 import { StyleSheet, Text, View, SafeAreaView, KeyboardAvoidingView, Platform, ScrollView, Alert } from 'react-native';
+import AsyncStorage from '@react-native-async-storage/async-storage';
 import { useNavigation, NavigationProp } from '@react-navigation/native';
 import { useAuthStore } from '@/store/authStore';
 import { Button, Input } from '@/components';
@@ -10,6 +11,10 @@ type RootStackParamList = {
   Register: undefined;
 };
 
+const LOGIN_ATTEMPT_KEY = '@shieldai_login_attempts';
+const MAX_ATTEMPTS = 5;
+const LOCKOUT_MS = 5 * 60 * 1000;
+
 export function LoginScreen() {
   const navigation = useNavigation<NavigationProp<RootStackParamList>>();
   const { login, isLoading, clearError } = useAuthStore();
@@ -27,11 +32,43 @@ export function LoginScreen() {
       return;
     }
 
+    const now = Date.now();
+    const stored = await AsyncStorage.getItem(LOGIN_ATTEMPT_KEY);
+    let attempts = { count: 0, lockedUntil: 0 };
+    if (stored) {
+      try {
+        attempts = JSON.parse(stored);
+      } catch { /* ignore corrupt data */ }
+    }
+
+    if (attempts.lockedUntil > now) {
+      const remaining = Math.ceil((attempts.lockedUntil - now) / 1000 / 60);
+      setFormError(`Too many failed attempts. Try again in ${remaining} minute${remaining !== 1 ? 's' : ''}.`);
+      return;
+    }
+
+    if (attempts.count >= MAX_ATTEMPTS && attempts.lockedUntil <= now) {
+      attempts.lockedUntil = now + LOCKOUT_MS;
+      attempts.count = 0;
+      await AsyncStorage.setItem(LOGIN_ATTEMPT_KEY, JSON.stringify(attempts));
+      const remaining = Math.ceil(LOCKOUT_MS / 1000 / 60);
+      setFormError(`Too many failed attempts. Locked for ${remaining} minutes.`);
+      return;
+    }
+
     try {
       await login(email, password);
+      await AsyncStorage.removeItem(LOGIN_ATTEMPT_KEY);
     } catch (err: any) {
-      setFormError(err.message || 'Login failed. Please try again.');
-      Alert.alert('Login Failed', err.message || 'Please check your credentials and try again.');
+      attempts.count = (attempts.count || 0) + 1;
+      if (attempts.count >= MAX_ATTEMPTS) {
+        attempts.lockedUntil = Date.now() + LOCKOUT_MS;
+      }
+      await AsyncStorage.setItem(LOGIN_ATTEMPT_KEY, JSON.stringify(attempts));
+      const remaining = MAX_ATTEMPTS - attempts.count;
+      const warning = remaining > 0 ? ` ${remaining} attempt${remaining !== 1 ? 's' : ''} remaining.` : '';
+      setFormError(err.message || 'Login failed. Please try again.' + warning);
+      Alert.alert('Login Failed', err.message || 'Please check your credentials and try again.' + warning);
     }
   };
 
diff --git a/packages/mobile/src/screens/darkwatch/DarkWatchScreen.tsx b/packages/mobile/src/screens/darkwatch/DarkWatchScreen.tsx
index af646df..e55573b 100644
--- a/packages/mobile/src/screens/darkwatch/DarkWatchScreen.tsx
+++ b/packages/mobile/src/screens/darkwatch/DarkWatchScreen.tsx
@@ -11,9 +11,28 @@ export function DarkWatchScreen() {
   const [newItemName, setNewItemName] = useState('');
   const [newItemValue, setNewItemValue] = useState('');
   const [newItemType, setNewItemType] = useState<WatchListItem['entityType']>('person');
+  const [validationError, setValidationError] = useState('');
+
+  const validateWatchItem = (name: string, value: string, type: string): string | null => {
+    if (!name.trim() || !value.trim()) return 'Name and value are required';
+    if (name.length > 100) return 'Name must be 100 characters or less';
+    if (value.length > 200) return 'Value must be 200 characters or less';
+    if (type === 'email' && !/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(value)) {
+      return 'Enter a valid email address';
+    }
+    if (type === 'phone' && !/^\+?[\d\s-()]{7,20}$/.test(value)) {
+      return 'Enter a valid phone number';
+    }
+    return null;
+  };
 
   const handleAddItem = async () => {
-    if (!newItemName || !newItemValue) return;
+    const error = validateWatchItem(newItemName, newItemValue, newItemType);
+    if (error) {
+      setValidationError(error);
+      return;
+    }
+    setValidationError('');
 
     await addWatchItem({
       name: newItemName,
@@ -125,6 +144,12 @@ export function DarkWatchScreen() {
           <View style={styles.modalContent}>
             <Text style={styles.modalTitle}>Add Watch Item</Text>
 
+            {validationError && (
+              <Text style={{ color: COLORS.danger, fontSize: FONT_SIZES.sm, marginBottom: SPACING.sm }}>
+                {validationError}
+              </Text>
+            )}
+
             <Input
               label="Name"
               placeholder="e.g., John Doe"
diff --git a/packages/mobile/src/screens/settings/SettingsScreen.tsx b/packages/mobile/src/screens/settings/SettingsScreen.tsx
index 776c676..8e25d64 100644
--- a/packages/mobile/src/screens/settings/SettingsScreen.tsx
+++ b/packages/mobile/src/screens/settings/SettingsScreen.tsx
@@ -80,7 +80,18 @@ export function SettingsScreen() {
               value={features.maxExposures === -1 ? 'Unlimited' : `${features.maxExposures}`}
             />
           </View>
-          <Button title="Upgrade Plan" onPress={() => {}} variant="secondary" fullWidth />
+          <Button
+              title="Upgrade Plan"
+              onPress={() =>
+                Alert.alert(
+                  'Upgrade Plan',
+                  'Billing integration coming soon. Contact support@shieldai.freno.me to upgrade.',
+                  [{ text: 'OK' }]
+                )
+              }
+              variant="secondary"
+              fullWidth
+            />
         </Card>
 
         <Card title="Notifications">
diff --git a/packages/mobile/src/services/api.ts b/packages/mobile/src/services/api.ts
index c39a29f..115b39f 100644
--- a/packages/mobile/src/services/api.ts
+++ b/packages/mobile/src/services/api.ts
@@ -1,6 +1,11 @@
 import { createApiClient } from '@shieldai/mobile-api-client';
 import { API_URL } from '@/constants/theme';
 
+// TODO SEC-007: Add certificate pinning for production builds.
+// For Expo managed workflow, use expo-config-plugin with
+// react-native-config or implement via EAS build post-install hook.
+// Reference: https://docs.expo.dev/guides/using-network-security/
+
 createApiClient({
   baseURL: API_URL,
   timeout: 30000,
diff --git a/packages/mobile/src/services/encryptedStorage.ts b/packages/mobile/src/services/encryptedStorage.ts
new file mode 100644
index 0000000..d12da87
--- /dev/null
+++ b/packages/mobile/src/services/encryptedStorage.ts
@@ -0,0 +1,27 @@
+import AsyncStorage from '@react-native-async-storage/async-storage';
+import type { StateStorage } from 'zustand/middleware';
+import { createJSONStorage } from 'zustand/middleware';
+import { encryptText, decryptText } from './secureStorage';
+
+function createEncryptedAsyncStorage(): StateStorage {
+  return {
+    getItem: async (name: string): Promise<string | null> => {
+      const encrypted = await AsyncStorage.getItem(name);
+      if (encrypted === null) return null;
+      try {
+        return await decryptText(encrypted);
+      } catch {
+        return null;
+      }
+    },
+    setItem: async (name: string, value: string): Promise<void> => {
+      const encrypted = await encryptText(value);
+      await AsyncStorage.setItem(name, encrypted);
+    },
+    removeItem: async (name: string): Promise<void> => {
+      await AsyncStorage.removeItem(name);
+    },
+  };
+}
+
+export const encryptedStorage = createJSONStorage(() => createEncryptedAsyncStorage());
diff --git a/packages/mobile/src/services/index.ts b/packages/mobile/src/services/index.ts
index b1c13e7..38f6c71 100644
--- a/packages/mobile/src/services/index.ts
+++ b/packages/mobile/src/services/index.ts
@@ -1 +1,2 @@
 export * from './api';
+export * from './secureStorage';
diff --git a/packages/mobile/src/services/secureStorage.ts b/packages/mobile/src/services/secureStorage.ts
new file mode 100644
index 0000000..65b3e88
--- /dev/null
+++ b/packages/mobile/src/services/secureStorage.ts
@@ -0,0 +1,75 @@
+import * as SecureStore from 'expo-secure-store';
+import { randomUUID } from 'expo-crypto';
+
+const ACCESS_TOKEN_KEY = '@shieldai_access_token';
+const REFRESH_TOKEN_KEY = '@shieldai_refresh_token';
+
+export async function getAccessToken(): Promise<string | null> {
+  return SecureStore.getItemAsync(ACCESS_TOKEN_KEY);
+}
+
+export async function setAccessToken(token: string): Promise<void> {
+  await SecureStore.setItemAsync(ACCESS_TOKEN_KEY, token);
+}
+
+export async function getRefreshToken(): Promise<string | null> {
+  return SecureStore.getItemAsync(REFRESH_TOKEN_KEY);
+}
+
+export async function setRefreshToken(token: string): Promise<void> {
+  await SecureStore.setItemAsync(REFRESH_TOKEN_KEY, token);
+}
+
+export async function clearTokens(): Promise<void> {
+  try {
+    await SecureStore.deleteItemAsync(ACCESS_TOKEN_KEY);
+  } catch { /* may not exist */ }
+  try {
+    await SecureStore.deleteItemAsync(REFRESH_TOKEN_KEY);
+  } catch { /* may not exist */ }
+}
+
+// XOR cipher for PII in AsyncStorage.
+// Key stored in SecureStore (Keychain/Keystore).
+const CIPHER_KEY_FILE = '@shieldai_cipher_key';
+
+async function getCipherKey(): Promise<number[]> {
+  let keyStr = await SecureStore.getItemAsync(CIPHER_KEY_FILE);
+  if (!keyStr) {
+    keyStr = randomUUID();
+    await SecureStore.setItemAsync(CIPHER_KEY_FILE, keyStr);
+  }
+  return keyStr.split('').map((c) => c.charCodeAt(0));
+}
+
+function xorEncode(str: string, key: number[]): string {
+  const codePoints: number[] = [];
+  for (let i = 0; i < str.length; i++) {
+    codePoints.push(str.charCodeAt(i) ^ key[i % key.length]);
+  }
+  // Encode as base64 using Buffer (available in RN)
+  return Buffer.from(codePoints).toString('base64');
+}
+
+function xorDecode(encoded: string, key: number[]): string {
+  try {
+    const codePoints = Array.from(Buffer.from(encoded, 'base64'));
+    const chars: string[] = [];
+    for (let i = 0; i < codePoints.length; i++) {
+      chars.push(String.fromCharCode(codePoints[i] ^ key[i % key.length]));
+    }
+    return chars.join('');
+  } catch {
+    return '';
+  }
+}
+
+export async function encryptText(plain: string): Promise<string> {
+  const key = await getCipherKey();
+  return xorEncode(plain, key);
+}
+
+export async function decryptText(encrypted: string): Promise<string> {
+  const key = await getCipherKey();
+  return xorDecode(encrypted, key);
+}
diff --git a/packages/mobile/src/store/authStore.ts b/packages/mobile/src/store/authStore.ts
index 43cf190..96ea903 100644
--- a/packages/mobile/src/store/authStore.ts
+++ b/packages/mobile/src/store/authStore.ts
@@ -1,13 +1,19 @@
 import { create } from 'zustand';
-import { persist, createJSONStorage } from 'zustand/middleware';
-import AsyncStorage from '@react-native-async-storage/async-storage';
+import { persist } from 'zustand/middleware';
 import type { User } from '@/types';
 import { authService } from '@shieldai/mobile-api-client';
 import { AUTH_STORAGE_KEY } from '@/constants';
+import {
+  getAccessToken,
+  setAccessToken,
+  getRefreshToken,
+  setRefreshToken,
+  clearTokens,
+} from '@/services/secureStorage';
+import { encryptedStorage } from '@/services/encryptedStorage';
 
 interface AuthState {
   user: User | null;
-  accessToken: string | null;
   isAuthenticated: boolean;
   isLoading: boolean;
   error: string | null;
@@ -16,6 +22,8 @@ interface AuthState {
   logout: () => Promise<void>;
   clearError: () => void;
   setUser: (user: User | null) => void;
+  refreshSession: () => Promise<boolean>;
+  hydrateTokens: () => Promise<void>;
 }
 
 const toAppUser = (apiUser: any): User => ({
@@ -31,7 +39,6 @@ export const useAuthStore = create<AuthState>()(
   persist(
     (set, get) => ({
       user: null,
-      accessToken: null,
       isAuthenticated: false,
       isLoading: false,
       error: null,
@@ -40,9 +47,12 @@ export const useAuthStore = create<AuthState>()(
         set({ isLoading: true, error: null });
         try {
           const { user: apiUser, tokens } = await authService.login({ email, password });
+          await setAccessToken(tokens.accessToken);
+          if (tokens.refreshToken) {
+            await setRefreshToken(tokens.refreshToken);
+          }
           set({
             user: toAppUser(apiUser),
-            accessToken: tokens.accessToken,
             isAuthenticated: true,
             isLoading: false,
           });
@@ -64,9 +74,12 @@ export const useAuthStore = create<AuthState>()(
             firstName,
             lastName,
           });
+          await setAccessToken(tokens.accessToken);
+          if (tokens.refreshToken) {
+            await setRefreshToken(tokens.refreshToken);
+          }
           set({
             user: toAppUser(apiUser),
-            accessToken: tokens.accessToken,
             isAuthenticated: true,
             isLoading: false,
           });
@@ -83,24 +96,55 @@ export const useAuthStore = create<AuthState>()(
         try {
           await authService.logout();
         } finally {
+          await clearTokens();
           set({
             user: null,
-            accessToken: null,
             isAuthenticated: false,
             error: null,
           });
         }
       },
 
+      refreshSession: async (): Promise<boolean> => {
+        const refreshToken = await getRefreshToken();
+        if (!refreshToken) return false;
+        try {
+          const newTokens = await authService.refreshToken();
+          await setAccessToken(newTokens.accessToken);
+          if (newTokens.refreshToken) {
+            await setRefreshToken(newTokens.refreshToken);
+          }
+          return true;
+        } catch {
+          await clearTokens();
+          set({ user: null, isAuthenticated: false });
+          return false;
+        }
+      },
+
+      hydrateTokens: async () => {
+        const token = await getAccessToken();
+        if (token) {
+          try {
+            const user = await authService.getCurrentUser();
+            if (user) {
+              set({ user: toAppUser(user), isAuthenticated: true });
+            }
+          } catch {
+            await clearTokens();
+            set({ user: null, isAuthenticated: false });
+          }
+        }
+      },
+
       clearError: () => set({ error: null }),
       setUser: (user) => set({ user, isAuthenticated: !!user }),
     }),
     {
       name: AUTH_STORAGE_KEY,
-      storage: createJSONStorage(() => AsyncStorage),
+      storage: encryptedStorage,
       partialize: (state) => ({
         user: state.user,
-        accessToken: state.accessToken,
         isAuthenticated: state.isAuthenticated,
       }),
     }
diff --git a/packages/mobile/src/store/darkWatchStore.ts b/packages/mobile/src/store/darkWatchStore.ts
index 839ebe1..54c9de6 100644
--- a/packages/mobile/src/store/darkWatchStore.ts
+++ b/packages/mobile/src/store/darkWatchStore.ts
@@ -1,8 +1,8 @@
 import { create } from 'zustand';
-import { persist, createJSONStorage } from 'zustand/middleware';
-import AsyncStorage from '@react-native-async-storage/async-storage';
+import { persist } from 'zustand/middleware';
 import { randomUUID } from 'expo-crypto';
 import type { WatchListItem, Exposure } from '@/types';
+import { encryptedStorage } from '@/services/encryptedStorage';
 
 /**
  * TODO: Wire store operations to @shieldai/mobile-api-client for production.
@@ -62,7 +62,7 @@ export const useDarkWatchStore = create<DarkWatchState>()(
     }),
     {
       name: '@shieldai_darkwatch',
-      storage: createJSONStorage(() => AsyncStorage),
+      storage: encryptedStorage,
     }
   )
 );
diff --git a/packages/mobile/src/store/settingsStore.ts b/packages/mobile/src/store/settingsStore.ts
index ac1223c..e5787cb 100644
--- a/packages/mobile/src/store/settingsStore.ts
+++ b/packages/mobile/src/store/settingsStore.ts
@@ -1,7 +1,7 @@
 import { create } from 'zustand';
-import { persist, createJSONStorage } from 'zustand/middleware';
-import AsyncStorage from '@react-native-async-storage/async-storage';
+import { persist } from 'zustand/middleware';
 import type { NotificationPreference } from '@/types';
+import { encryptedStorage } from '@/services/encryptedStorage';
 
 /**
  * TODO: Wire updatePreferences to notificationService.updatePreferences() for production.
@@ -39,7 +39,7 @@ export const useSettingsStore = create<SettingsState>()(
     }),
     {
       name: '@shieldai_settings',
-      storage: createJSONStorage(() => AsyncStorage),
+      storage: encryptedStorage,
     }
   )
 );
diff --git a/packages/mobile/src/store/spamShieldStore.ts b/packages/mobile/src/store/spamShieldStore.ts
index 9d4d661..4df4058 100644
--- a/packages/mobile/src/store/spamShieldStore.ts
+++ b/packages/mobile/src/store/spamShieldStore.ts
@@ -1,7 +1,7 @@
 import { create } from 'zustand';
-import { persist, createJSONStorage } from 'zustand/middleware';
-import AsyncStorage from '@react-native-async-storage/async-storage';
+import { persist } from 'zustand/middleware';
 import type { SpamRecord } from '@/types';
+import { encryptedStorage } from '@/services/encryptedStorage';
 
 /**
  * TODO: Wire store operations to @shieldai/mobile-api-client for production.
@@ -57,7 +57,7 @@ export const useSpamShieldStore = create<SpamShieldState>()(
     }),
     {
       name: '@shieldai_spamshield',
-      storage: createJSONStorage(() => AsyncStorage),
+      storage: encryptedStorage,
     }
   )
 );
diff --git a/packages/mobile/src/store/voicePrintStore.ts b/packages/mobile/src/store/voicePrintStore.ts
index 096c9ac..e3e85aa 100644
--- a/packages/mobile/src/store/voicePrintStore.ts
+++ b/packages/mobile/src/store/voicePrintStore.ts
@@ -1,8 +1,8 @@
 import { create } from 'zustand';
-import { persist, createJSONStorage } from 'zustand/middleware';
-import AsyncStorage from '@react-native-async-storage/async-storage';
+import { persist } from 'zustand/middleware';
 import { randomUUID } from 'expo-crypto';
 import type { VoiceProfile, VoiceAnalysis } from '@/types';
+import { encryptedStorage } from '@/services/encryptedStorage';
 
 /**
  * TODO: Wire store operations to @shieldai/mobile-api-client for production.
@@ -50,7 +50,7 @@ export const useVoicePrintStore = create<VoicePrintState>()(
     }),
     {
       name: '@shieldai_voiceprint',
-      storage: createJSONStorage(() => AsyncStorage),
+      storage: encryptedStorage,
     }
   )
 );