import type { AppendRecord, ReadRecord } from "./lib/stream/types.js";
/**
 * Calculate the UTF-8 byte length of a string.
 * Handles all Unicode characters including surrogate pairs correctly.
 *
 * @param str The string to measure
 * @returns The byte length when encoded as UTF-8
 */
export declare function utf8ByteLength(str: string): number;
/**
 * Calculate the metered size in bytes of a record (append or read).
 * This includes the body and headers, but not metadata like timestamp.
 *
 * This function calculates how many bytes the record will occupy
 * after being received and deserialized as raw bytes on the S2 side.
 * For strings, it calculates UTF-8 byte length. For Uint8Array, it uses
 * the array length directly (same value as would be used when encoding
 * to base64 for transmission).
 *
 * @param record The record to measure
 * @returns The size in bytes
 */
export declare function meteredBytes<Format extends "string" | "bytes">(record: AppendRecord | ReadRecord<Format>): number;
/**
 * Whether this is a command record.
 * Command records have exactly one header with an empty name.
 */
export declare function isCommandRecord(record: {
    headers?: ReadonlyArray<readonly [string, string]> | ReadonlyArray<readonly [Uint8Array, Uint8Array]> | Array<[string, string]> | Array<[Uint8Array, Uint8Array]> | null;
}): boolean;
export declare function computeAppendRecordFormat(record: AppendRecord): "string" | "bytes";
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