/**
 * Emitted when VAD detects the start of speech (endpointing=vad only).
 */
export interface RealtimeVadSpeechStart {
    event: "vad.speech_start";
    /** Zero-based utterance counter for the session */
    utterance_idx: number;
    /** VAD confidence (0.0–1.0) */
    confidence?: number | undefined;
}