/**
 * Safe custom element registration utility
 *
 * Prevents "NotSupportedError: the name X has already been used with this registry"
 * by checking if an element is already registered before defining it.
 *
 * Usage:
 * ```typescript
 * import { safeDefineElement } from './utils/safe-element-registry';
 *
 * // Instead of: customElements.define('my-element', MyElement);
 * safeDefineElement('my-element', MyElement);
 * ```
 */
/**
 * Safely define a custom element, checking if it's already registered
 * @param tagName - The custom element tag name (must include a hyphen)
 * @param elementClass - The custom element class (extends HTMLElement)
 * @returns The element class (whether newly registered or already existing)
 */
export declare function safeDefineElement(tagName: string, elementClass: CustomElementConstructor): CustomElementConstructor;
/**
 * Check if a custom element is already registered
 * @param tagName - The custom element tag name
 * @returns true if registered, false otherwise
 */
export declare function isElementDefined(tagName: string): boolean;