import type { MaybeRefOrGetter } from 'vue';
/**
 * `false` until `open` is first truthy, then `true` for good. Preloads the overlay once idle after mount.
 */
export declare function useLazyOverlay(open: MaybeRefOrGetter<boolean | undefined>, preload: () => Promise<unknown>): import("vue").Ref<boolean, boolean>;