Clear mnemonic seed phrase from clipboard after import

src/app/wallet-setup/import-wallet.tsx

@@ -17,11 +17,13 @@ import {
 } from 'react-native';
 import { useSafeAreaInsets } from 'react-native-safe-area-context';
 import { toast } from 'sonner-native';
+import { useMnemonicClipboardCleanup } from '@/hooks/useMnemonicClipboardCleanup';
 
 export default function ImportWalletScreen() {
   const router = useDebouncedNavigation();
   const insets = useSafeAreaInsets();
   const [secretWords, setSecretWords] = useState<string[]>(Array(12).fill(''));
+  const { scheduleClearClipboard } = useMnemonicClipboardCleanup();
 
   const handleWordChange = (index: number, text: string) => {
     const newWords = [...secretWords];
@@ -56,6 +58,7 @@ export default function ImportWalletScreen() {
       setSecretWords(newWords);
 
       toast.success('12 words have been pasted from clipboard');
+      scheduleClearClipboard(words.join(' '));
     } catch (error) {
       console.error('Paste error:', error);
       toast.error('Could not paste from clipboard');
@@ -69,7 +72,7 @@ export default function ImportWalletScreen() {
   };
 
   const isFormValid = () => {
-    return secretWords.every(word => word.trim().length > 0);
+    return secretWords.every((word) => word.trim().length > 0);
   };
 
   const validateSeedPhrase = (phrase: string): boolean => {

src/hooks/useMnemonicClipboardCleanup.ts

@@ -0,0 +1,45 @@
+import * as Clipboard from 'expo-clipboard';
+import { useEffect, useRef } from 'react';
+
+const CLEAR_CLIPBOARD_AFTER_MS = 5 * 60 * 1000; //5 mins
+
+const normalizePhrase = (s: string) => s.trim().toLowerCase().replace(/\s+/g, ' ');
+
+const checkIsMnemonic = (s: string) => {
+  const words = normalizePhrase(s).split(' ');
+  return words.length === 12 && words.every(Boolean);
+};
+
+export function useMnemonicClipboardCleanup() {
+  const timerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
+  const lastMnemonicRef = useRef<string | null>(null);
+
+  const scheduleClearClipboard = (mnemonic: string) => {
+    if (timerRef.current) clearTimeout(timerRef.current);
+
+    lastMnemonicRef.current = normalizePhrase(mnemonic);
+
+    timerRef.current = setTimeout(async () => {
+      try {
+        const current = await Clipboard.getStringAsync();
+        const normalizedCurrent = normalizePhrase(current);
+
+        if (
+          lastMnemonicRef.current &&
+          normalizedCurrent === lastMnemonicRef.current &&
+          checkIsMnemonic(normalizedCurrent)
+        ) {
+          await Clipboard.setStringAsync('');
+        }
+      } catch {}
+    }, CLEAR_CLIPBOARD_AFTER_MS);
+  };
+
+  useEffect(() => {
+    return () => {
+      if (timerRef.current) clearTimeout(timerRef.current);
+    };
+  }, []);
+
+  return { scheduleClearClipboard };
+}