/**
 * Validates lock ID format (22 base64url characters from 16 bytes CSPRNG).
 * Client-side validation for immediate feedback before backend operations.
 * Prevents round-trip latency for malformed inputs.
 *
 * @param lockId - Lock identifier to validate
 * @throws {LockError} InvalidArgument for format violations (empty, wrong length, invalid characters)
 * @see docs/specs/interface.md#acquire-operation-requirements - Normative lockId validation requirement
 * @see docs/specs/interface.md#security-considerations - Lock ID security and CSPRNG requirements
 */
export declare function validateLockId(lockId: string): void;
/**
 * Normalizes key to Unicode NFC and validates length constraints.
 * Prevents encoding-based key collisions (e.g., "café" vs "cafe\u0301").
 *
 * @param key - User-provided lock key
 * @returns Normalized key safe for backend storage
 * @throws {LockError} InvalidArgument for empty/oversized keys (max 512 bytes after NFC normalization)
 * @see docs/specs/interface.md#core-constants - Normative MAX_KEY_LENGTH_BYTES requirement
 * @see common/constants.ts - MAX_KEY_LENGTH_BYTES constant definition
 */
export declare function normalizeAndValidateKey(key: string): string;