/**
 * Copyright © 2026 Anonyome Labs, Inc. All rights reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 */
/**
 * Calculate the UTF-8 byte length of a string in a cross-environment manner.
 * Uses `Buffer.byteLength` when available (Node.js), otherwise falls back
 * to `TextEncoder` (browser).
 */
export declare function utf8ByteLength(str: string): number;