/**
 * Internal custom overlay registry.
 *
 * The public overlay-state schema version 1 wire format supports custom
 * overlays with namespaced customType values. This internal registry leaves
 * room for future public registration without making Fabric object JSON part
 * of the persistence API.
 *
 * @module
 */
import type { OverlaySerializerRegistryEntry } from './overlay-state-types.js';
export declare function registerOverlaySerializer(customType: string, entry: OverlaySerializerRegistryEntry): void;
export declare function getOverlaySerializer(customType: string): OverlaySerializerRegistryEntry | undefined;