/**
 * Runtime Detection
 *
 * Utilities for detecting whether code is running in Node.js or browser environment.
 */
/**
 * Check if running in Node.js environment.
 */
export declare function isNode(): boolean;
/**
 * Check if running in a browser-like environment with Web Crypto API.
 */
export declare function isBrowser(): boolean;
/**
 * Assert that code is running in Node.js.
 * @throws Error if not in Node.js environment
 */
export declare function assertNode(feature: string): void;