export type MagicDetectedMimeType = 'image/png' | 'image/jpeg' | 'image/gif' | 'image/webp' | 'image/avif' | 'application/pdf' | 'application/vnd.openxmlformats-officedocument.wordprocessingml.document' | 'application/zip' | 'video/mp4' | 'video/webm' | 'video/quicktime' | 'audio/mpeg' | 'audio/mp4' | 'audio/flac' | 'audio/wav' | 'audio/ogg';
/**
 * Detects a conservative MIME type from file magic bytes only.
 *
 * This intentionally ignores caller-provided Content-Type headers because signed
 * upload clients control those headers. Unsupported or ambiguous signatures
 * return undefined so policy checks can fail closed.
 */
export declare function detectMimeTypeFromBuffer(buffer: Uint8Array | null | undefined): MagicDetectedMimeType | undefined;
export declare function bufferAsLatin1(buffer: Uint8Array, maxBytes?: number): string;
