chore: initial import

apps/visualizer/src/app/hooks/useInterval.ts

@@ -0,0 +1,15 @@
+import { useEffect, useRef } from 'react';
+
+export function useInterval(callback: () => void, delayMs: number | null) {
+  const cbRef = useRef(callback);
+  cbRef.current = callback;
+
+  useEffect(() => {
+    if (delayMs == null) return;
+    if (!Number.isFinite(delayMs) || delayMs < 0) return;
+
+    const id = window.setInterval(() => cbRef.current(), delayMs);
+    return () => window.clearInterval(id);
+  }, [delayMs]);
+}
+

apps/visualizer/src/app/hooks/useLocalStorageState.ts

@@ -0,0 +1,24 @@
+import { useEffect, useState } from 'react';
+
+export function useLocalStorageState<T>(key: string, initialValue: T) {
+  const [value, setValue] = useState<T>(() => {
+    try {
+      const raw = window.localStorage.getItem(key);
+      if (raw == null) return initialValue;
+      return JSON.parse(raw) as T;
+    } catch {
+      return initialValue;
+    }
+  });
+
+  useEffect(() => {
+    try {
+      window.localStorage.setItem(key, JSON.stringify(value));
+    } catch {
+      // ignore
+    }
+  }, [key, value]);
+
+  return [value, setValue] as const;
+}
+