/**
 * TTS engine contract.
 *
 * The shared types and event names for Kokoro speech synthesis, implemented by
 * kokoro.ts and consumed by tts-stream.ts. Nothing else lives here.
 */
import type { GatewayEmit } from "../shared/gateway-events.js";
/** WebSocket event names emitted during synthesis (envelope: { event, payload, ts }). */
export declare const TALK_EVENTS: {
    readonly audio: "talk:audio";
    readonly ttsDownloadProgress: "talk:tts:download:progress";
    readonly ttsDownloadComplete: "talk:tts:download:complete";
    readonly ttsDownloadError: "talk:tts:download:error";
};
/** Broadcast function injected everywhere (matches gateway server's `emit`). */
export type Emit = GatewayEmit;
/** Kokoro-82M TTS engine (sidecar-backed). Implemented by kokoro.ts. */
export interface Tts {
    /**
     * Synthesize `text`, sentence-chunked, streaming talk:audio events; resolves
     * with the number of chunks emitted. `seqStart` continues a per-turn monotonic
     * sequence across calls; `final:false` suppresses the `last:true` flag so a
     * turn streamed sentence-by-sentence only signals end-of-audio on the flush.
     */
    speak(sessionId: string, text: string, emit: Emit, opts?: {
        seqStart?: number;
        final?: boolean;
    }): Promise<number>;
    /**
     * One-shot synthesis of arbitrary `text` into a single WAV buffer (no WS
     * streaming). Backs the standalone POST /api/tts read-aloud surface. Rejects if
     * the engine is unavailable (missing venv/weights).
     */
    synthesize(text: string): Promise<Buffer>;
    status(): {
        available: boolean;
        downloading: boolean;
        progress: number;
        voice: string;
        ready: boolean;
    };
    /** Pre-spawn the sidecar and load the model so the first real speak is fast. No-op if weights/venv are missing. */
    warm?(): Promise<void>;
    /** Download Kokoro weights on first use, emitting talk:tts:download:* events. */
    download(emit: Emit): Promise<void>;
    shutdown(): void;
}
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