/**
 * @module infra/audio-player
 *
 * Cross-platform local audio playback — the Windows/Linux counterpart of
 * macOS `afplay`. One resolver feeds every audible feature: spoken replies
 * (tui-speak), the reply ping and composed chimes (infra/sound), and any
 * future file playback. Returns a killable ChildProcess so barge-in and
 * stopSpeaking semantics carry over unchanged.
 *
 * Resolution per platform:
 *   darwin: afplay (native, always present)
 *   win32:  ffplay when available (ships with the ffmpeg the voice listener
 *           already requires) → PowerShell PresentationCore MediaPlayer
 *           (dependency-free; handles mp3 + wav)
 *   linux:  ffplay → mpv → mpg123 (first available)
 */
import { type ChildProcess } from "node:child_process";
/**
 * Play an audio file (mp3/wav/aiff per platform player). Fire-and-forget by
 * default; `onExit` fires when playback ends or fails. Returns the process
 * (kill() stops playback) or null when no player exists on this system.
 */
export declare function playAudioFile(file: string, opts?: {
    volume?: number;
    rate?: number;
    onExit?: () => void;
}): ChildProcess | null;