/** Deep equality for JSON-like sync payloads (objects, arrays, primitives). */
export default function isEqual(a: unknown, b: unknown): boolean {
  if (a === b) return true;
  if (a == null || b == null) return false;
  if (typeof a !== typeof b) return false;
  if (typeof a !== "object") return false;

  if (Array.isArray(a)) {
    if (!Array.isArray(b) || a.length !== b.length) return false;
    return a.every((v, i) => isEqual(v, b[i]));
  }

  if (Array.isArray(b)) return false;

  const aObj = a as Record<string, unknown>;
  const bObj = b as Record<string, unknown>;
  const aKeys = Object.keys(aObj);
  if (aKeys.length !== Object.keys(bObj).length) return false;
  return aKeys.every((k) => isEqual(aObj[k], bObj[k]));
}