feat(vault): show mnemonic flow will show at first time ; or user reset vault state;

src/screens/VaultScreen.tsx

@@ -25,6 +25,8 @@ import { VaultAsset, VaultAssetType, Heir } from '../types';
 import BiometricModal from '../components/common/BiometricModal';
 import { useAuth } from '../context/AuthContext';
 import { useVaultAssets } from '../hooks/useVaultAssets';
+import { VAULT_STORAGE_KEYS } from '../config';
+import { mnemonicToEntropy, splitSecret, serializeShare } from '../utils/sss';
 
 // Asset type configuration with nautical theme
 const assetTypeConfig: Record<VaultAssetType, { icon: string; iconType: 'ionicons' | 'feather' | 'material' | 'fontawesome5'; label: string }> = {
@@ -168,6 +170,7 @@ export default function VaultScreen() {
   const [accountProvider, setAccountProvider] = useState<'bank' | 'steam' | 'facebook' | 'custom'>('bank');
   const [showMnemonic, setShowMnemonic] = useState(false);
   const [showLegacyAssignCta, setShowLegacyAssignCta] = useState(false);
+  const [hasS0, setHasS0] = useState<boolean | null>(null);
   const [mnemonicWords, setMnemonicWords] = useState<string[]>([]);
   const [mnemonicParts, setMnemonicParts] = useState<string[][]>([]);
   const [mnemonicStep, setMnemonicStep] = useState<1 | 2 | 3 | 4 | 5>(1);
@@ -185,15 +188,31 @@ export default function VaultScreen() {
   const mnemonicRef = useRef<View>(null);
   const progressTimerRef = useRef<ReturnType<typeof setInterval> | null>(null);
 
+  // Detect S0 (TEE/SE): if present, later open shows biometric only; if not, mnemonic flow
   useEffect(() => {
-    if (!isUnlocked) {
-      const timer = setTimeout(() => {
-        setShowBiometric(true);
-      }, 500);
-      return () => clearTimeout(timer);
-    }
+    let cancelled = false;
+    AsyncStorage.getItem(VAULT_STORAGE_KEYS.SHARE_DEVICE)
+      .then((v) => {
+        if (!cancelled) setHasS0(!!v);
+      })
+      .catch(() => {
+        if (!cancelled) setHasS0(false);
+      });
+    return () => { cancelled = true; };
   }, []);
 
+  // Only when S0 exists and vault not unlocked: show biometric after short delay.
+  // When hasS0 is false or null, never show biometric — go straight to mnemonic flow.
+  useEffect(() => {
+    if (hasS0 !== true) {
+      setShowBiometric(false);
+      return;
+    }
+    if (isUnlocked) return;
+    const timer = setTimeout(() => setShowBiometric(true), 500);
+    return () => clearTimeout(timer);
+  }, [isUnlocked, hasS0]);
+
   useEffect(() => {
     if (isUnlocked) {
       Animated.timing(fadeAnim, {
@@ -335,28 +354,49 @@ export default function VaultScreen() {
 
   const handleHeirDecision = (share: boolean) => {
     // Placeholder for future heir flow
-    setShowMnemonic(false);
-    setIsUnlocked(true);
+    finishMnemonicThenShowBiometric();
   };
 
   const handleSubmitAssignment = () => {
     // Placeholder for submitting assignment to API
-    setShowMnemonic(false);
-    setIsUnlocked(true);
+    finishMnemonicThenShowBiometric();
   };
 
   const handleHeirYes = () => {
-    setShowMnemonic(false);
-    setIsUnlocked(true);
+    finishMnemonicThenShowBiometric();
     setShowLegacyAssignCta(true);
   };
 
   const handleHeirNo = () => {
-    setShowMnemonic(false);
-    setIsUnlocked(true);
+    finishMnemonicThenShowBiometric();
     setShowLegacyAssignCta(true);
   };
 
+  /** After mnemonic flow: persist S0 (simulated TEE/SE via AsyncStorage), then show biometric; unlock on success */
+  const finishMnemonicThenShowBiometric = async () => {
+    try {
+      const wordList = bip39.wordlists.english;
+      const entropy = mnemonicToEntropy(mnemonicWords, wordList);
+      const shares = splitSecret(entropy);
+      const s0 = shares[0]; // device share (S0)
+      // S0 is stored in AsyncStorage under SHARE_DEVICE — app-level storage, not hardware TEE/SE
+      await AsyncStorage.setItem(VAULT_STORAGE_KEYS.SHARE_DEVICE, serializeShare(s0));
+      await AsyncStorage.setItem(VAULT_STORAGE_KEYS.INITIALIZED, '1');
+      setHasS0(true);
+      setShowMnemonic(false);
+      setShowBiometric(true);
+    } catch (e) {
+      if (__DEV__) console.warn('finishMnemonicThenShowBiometric', e);
+      setShowMnemonic(false);
+      setShowBiometric(true);
+    }
+  };
+
+  const handleBiometricSuccess = () => {
+    setShowBiometric(false);
+    setIsUnlocked(true);
+  };
+
   const handleOpenLegacyAssign = () => {
     setSelectedHeir(null);
     setSelectedHeirAsset(null);
@@ -888,7 +928,7 @@ export default function VaultScreen() {
               
               <TouchableOpacity
                 style={styles.unlockButton}
-                onPress={() => setShowBiometric(true)}
+                onPress={hasS0 ? () => setShowBiometric(true) : handleUnlock}
                 activeOpacity={0.8}
               >
                 <LinearGradient
@@ -897,8 +937,10 @@ export default function VaultScreen() {
                   start={{ x: 0, y: 0 }}
                   end={{ x: 1, y: 0 }}
                 >
-                  <Ionicons name="finger-print" size={20} color={colors.vault.background} />
-                  <Text style={styles.unlockButtonText}>Captain's Verification</Text>
+                  <Ionicons name={hasS0 ? 'finger-print' : 'key'} size={20} color={colors.vault.background} />
+                  <Text style={styles.unlockButtonText}>
+                    {hasS0 === true ? "Captain's Verification" : hasS0 === false ? 'Enter Vault' : 'Loading…'}
+                  </Text>
                 </LinearGradient>
               </TouchableOpacity>
             </View>
@@ -906,8 +948,8 @@ export default function VaultScreen() {
         </LinearGradient>
 
         <BiometricModal
-          visible={showBiometric}
-          onSuccess={handleUnlock}
+          visible={hasS0 === true && showBiometric}
+          onSuccess={handleBiometricSuccess}
           onCancel={() => setShowBiometric(false)}
           title="Enter the Vault"
           message="Verify your identity to access your treasures"