/** Provider-neutral speech synthesis contract (plan 061 Task 3).
 *  Text→audio bytes plus a streaming variant whose first chunk resolves as soon as the
 *  provider starts responding. Adapters enforce input caps with typed errors — they never
 *  silently truncate. Audio bytes use `Uint8Array`/`ReadableStream` (repo convention). */
import type { ModelCapabilities, ModelConfig } from "./content.js";
export interface SpeechRequest {
    readonly model: string;
    readonly input: string;
    /** Provider voice id, e.g. `alloy`. Adapter default when omitted. */
    readonly voice?: string;
    /** Audio container, e.g. `mp3`, `wav`, `opus`. Adapter default when omitted. */
    readonly format?: string;
    /** Playback speed multiplier (e.g. 0.25–4.0 on OpenAI). */
    readonly speed?: number;
    readonly signal?: AbortSignal;
}
export interface SpeechResult {
    readonly audio: Uint8Array;
    /** Actual audio container of `audio` (request value or provider default). */
    readonly format: string;
}
export interface SpeechStreamResult {
    /** Audio chunks in order; the first chunk is available as soon as the provider responds. */
    readonly audio: ReadableStream<Uint8Array>;
    /** Actual audio container of the stream (request value or provider default). */
    readonly format: string;
}
export interface SpeechProvider {
    readonly id: string;
    synthesize(request: SpeechRequest): Promise<SpeechResult>;
    synthesizeStream(request: SpeechRequest): Promise<SpeechStreamResult>;
}
export type SpeechErrorCode = "empty_input" | "input_too_large" | "request_failed" | "response_malformed" | "unsupported_model";
export declare class SpeechError extends Error {
    readonly code: SpeechErrorCode;
    constructor(code: SpeechErrorCode, message: string);
}
export declare function modelSupportsSpeech(capabilities?: ModelCapabilities): boolean;
export declare function assertSpeechSupported(model: ModelConfig): void;