/**
 * One-line hints for files that arrive with a chat message.
 *
 * A Slack voice message reaches the agent as `[Slack File: /…/F123-Audio_Clip.m4a
 * (audio/mp4, 214KB)]`. One agent knew to run `transcribe-audio`; another said
 * "I can't transcribe audio" and stopped. The path alone does not say which
 * skill reads the file, so the bridge adds a hint naming it — and what to do
 * when that skill is not set up yet (specs/skill-auto-install.md).
 *
 * PDFs already get their text extracted inline by the Slack bridge; a hint is
 * added only when that extraction failed or was cut short, so the agent is not
 * told twice about content it already has.
 *
 * @module utils/inbound-file-hint.utils
 */
/** File extensions treated as audio/video even when the MIME type is generic. */
export declare const AUDIO_VIDEO_EXTENSIONS: readonly ["m4a", "mp3", "wav", "aac", "ogg", "oga", "opus", "flac", "amr", "webm", "mp4", "m4v", "mov", "mkv", "caf"];
/** Marker the Slack bridge appends when it cuts extracted PDF text. */
export declare const EXTRACTED_TEXT_TRUNCATED_MARKER = "[truncated]";
/** The fields of an inbound file the hint needs. */
export interface InboundFile {
    name: string;
    mimetype: string;
    localPath: string;
    /** Text already extracted inline (PDFs) */
    extractedText?: string;
}
/**
 * Whether a file is audio or video.
 *
 * @param file - Inbound file
 * @returns True for audio/* or video/* MIME types or a known extension
 */
export declare function isAudioOrVideo(file: Pick<InboundFile, 'name' | 'mimetype'>): boolean;
/**
 * Whether a file is a PDF.
 *
 * @param file - Inbound file
 * @returns True for application/pdf or a .pdf name
 */
export declare function isPdf(file: Pick<InboundFile, 'name' | 'mimetype'>): boolean;
/**
 * The hint line for one inbound file, or null when none is needed.
 *
 * @param file - Inbound file
 * @returns e.g. `[Hint: voice/audio or video file — transcribe it with the transcribe-audio skill …]`
 *
 * @example
 * ```ts
 * inboundFileHint({ name: 'Audio Clip.m4a', mimetype: 'audio/mp4', localPath: '/tmp/a.m4a' });
 * // '[Hint: voice/audio or video file — use the transcribe-audio skill: {"audioFile":"/tmp/a.m4a"} …]'
 * ```
 */
export declare function inboundFileHint(file: InboundFile): string | null;
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