/**
 * PKCE (RFC 7636) primitives implemented on top of the Web Crypto API so the
 * same module works under Node.js 20+ and in browser runtimes alike.
 */
/**
 * Generate a PKCE verifier and the matching S256 challenge.
 * Built on Web Crypto so it remains runtime-agnostic.
 */
export declare function generatePKCE(): Promise<{
    verifier: string;
    challenge: string;
}>;
