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hooks/useShakeToShuffle.ts

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+/**
+ * useShakeToShuffle — accelerometer-based shake detection
+ * Triggers callback when device is shaken hard enough
+ */
+import { useEffect, useRef } from 'react';
+import { Accelerometer } from 'expo-sensors';
+import * as Haptics from 'expo-haptics';
+
+const SHAKE_THRESHOLD = 2.2;
+const SHAKE_COOLDOWN  = 1500; // ms
+
+export function useShakeToShuffle(onShake: () => void) {
+  const lastShake = useRef(0);
+
+  useEffect(() => {
+    Accelerometer.setUpdateInterval(100);
+    const sub = Accelerometer.addListener(({ x, y, z }) => {
+      const acc = Math.sqrt(x * x + y * y + z * z);
+      const now = Date.now();
+      if (acc > SHAKE_THRESHOLD && now - lastShake.current > SHAKE_COOLDOWN) {
+        lastShake.current = now;
+        Haptics.notificationAsync(Haptics.NotificationFeedbackType.Success);
+        onShake();
+      }
+    });
+    return () => sub.remove();
+  }, [onShake]);
+}