/**
 * Input payload accepted by `decodeAttachmentAsText`.
 *
 * @private internal utility for shared text decoding
 */
export type DecodeAttachmentAsTextInput = {
    /**
     * Raw file bytes to inspect and decode.
     */
    readonly bytes: ArrayBuffer | ArrayBufferView;
    /**
     * Original filename used for diagnostics.
     */
    readonly filename: string;
    /**
     * Optional MIME type from transport or storage metadata.
     */
    readonly mimeType?: string | null;
};
/**
 * Optional settings for `decodeAttachmentAsText`.
 *
 * @private internal utility for shared text decoding
 */
export type DecodeAttachmentAsTextOptions = {
    /**
     * Max bytes to decode before truncating the payload.
     *
     * @default 524288
     */
    readonly maxBytes?: number;
    /**
     * Forces text decoding even when the bytes look binary.
     *
     * @default false
     */
    readonly forceText?: boolean;
};
/**
 * Best-effort text-decoding result for one attachment or file.
 *
 * @private internal utility for shared text decoding
 */
export type DecodeAttachmentAsTextResult = {
    /**
     * Decoded text. Empty string when decoding is skipped for binary content.
     */
    readonly text: string;
    /**
     * Encoding label used for decoding, or `binary` when decoding was skipped.
     */
    readonly encodingUsed: string;
    /**
     * Confidence score from `0` to `1`.
     */
    readonly confidence?: number;
    /**
     * Human-readable warnings describing truncation or guessed encodings.
     */
    readonly warnings: Array<string>;
    /**
     * Whether the payload was classified as binary and therefore not decoded.
     */
    readonly wasBinary: boolean;
    /**
     * Whether the byte payload had to be truncated before decoding.
     */
    readonly isTruncated: boolean;
};
/**
 * Default byte limit for one best-effort text decode.
 *
 * @private constant of decodeAttachmentAsText
 */
export declare const DEFAULT_ATTACHMENT_TEXT_DECODE_BYTES: number;
/**
 * Best-effort decoder for uploaded or remote file bytes whose extension or encoding may be unknown.
 *
 * @private internal utility for shared text decoding
 */
export declare function decodeAttachmentAsText(input: DecodeAttachmentAsTextInput, options?: DecodeAttachmentAsTextOptions): DecodeAttachmentAsTextResult;