/**
 * Cartesia TTS Handler (synchronous /tts/bytes endpoint)
 *
 * Implements the standard `TTSHandler` synchronous-request contract on top
 * of Cartesia's REST `/tts/bytes` endpoint. The pre-existing
 * `adapters/tts/cartesiaHandler.ts` (`CartesiaStream`) targets the
 * realtime WebSocket flow used by the voice server and does NOT implement
 * `TTSHandler`; this file fills the gap so `nl.generate({ tts: { provider:
 * "cartesia" } })` works through the same `TTSProcessor` dispatch as
 * every other shipped TTS provider.
 *
 * @module voice/providers/CartesiaTTS
 * @see https://docs.cartesia.ai/api-reference/tts/bytes
 */
import type { TTSHandler, TTSOptions, TTSResult } from "../../types/index.js";
/**
 * Cartesia synchronous TTS handler.
 *
 * Auth: `X-API-Key: ${CARTESIA_API_KEY}` + `Cartesia-Version` header.
 */
export declare class CartesiaTTS implements TTSHandler {
    readonly maxTextLength = 5000;
    private readonly apiKey;
    private readonly baseUrl;
    private readonly apiVersion;
    constructor(apiKey?: string);
    isConfigured(): boolean;
    synthesize(text: string, options?: TTSOptions): Promise<TTSResult>;
    private mapOutputFormat;
    private effectiveFormat;
}
