add files listing

mobile/hooks/useFileWatcher.ts

@@ -0,0 +1,32 @@
+import { useEffect, useState, useCallback } from 'react';
+import { Platform } from 'react-native';
+import { ExpoDownloadDetectModule, FileDetectedEvent } from '../modules/expo-download-detect';
+
+export function useFileWatcher() {
+  const [newFiles, setNewFiles] = useState<FileDetectedEvent[]>([]);
+  const [isSupported] = useState(() => Platform.OS === 'android');
+
+  const clearNewFiles = useCallback(() => {
+    setNewFiles([]);
+  }, []);
+
+  useEffect(() => {
+    if (!isSupported) return;
+
+    ExpoDownloadDetectModule.startWatching();
+
+    const subscription = ExpoDownloadDetectModule.addListener('onNewFile', (event: FileDetectedEvent) => {
+      setNewFiles((prev) => {
+        if (prev.some((f) => f.id === event.id)) return prev;
+        return [...prev, event];
+      });
+    });
+
+    return () => {
+      subscription.remove();
+      ExpoDownloadDetectModule.stopWatching();
+    };
+  }, [isSupported]);
+
+  return { newFiles, clearNewFiles, isSupported };
+}