/**
 * Efficiently checks if a React directive (e.g., "use server", "use client")
 * is present in the code.
 *
 * This function is optimized for performance by only checking the first few
 * lines of the code, as directives must appear at the very top of a file.
 * It handles comments, whitespace, and any valid directive prologue
 * (e.g., "use strict").
 */
export declare function hasDirective(code: string, directive: string): boolean;