type ScreenConstructor<T> = {
    new (): T;
    screenIdentifier: string;
};
/**
 * Register a screen class. If its identifier matches the current screen,
 * instantiate it immediately and store as the singleton.
 * Returns the instance if created, or null otherwise.
 */
export declare function registerScreen<T>(Constructor: ScreenConstructor<T>): T | null;
/**
 * Get the current screen instance (throws if not initialized).
 */
export declare function getScreen<T>(): T;
/**
 * Clear the current instance.
 */
export declare function clearScreen(): void;
export {};