/**
 * Encodes the original client filename into a random, filesystem-safe tmp
 * filename, so the dehydrate/hydrate round-trip needs zero extra snapshot
 * state to recover it later (same trick PHP's TemporaryUploadedFile uses,
 * embedding metadata in the filename rather than a sidecar).
 * PHP parity: TemporaryUploadedFile's temp-name generation
 */
export declare function encodeTmpFilename(originalClientName: string): string;
/**
 * Defense-in-depth guard: throws if the given tmp filename is malformed or contains
 * potential path-traversal sequence.
 */
export declare function assertValidTmpFilename(name: string): void;
/**
 * Inverse of encodeTmpFilename — recovers the original client filename and
 * extension from a generated tmp filename.
 */
export declare function decodeTmpFilename(tmpFilename: string): {
    originalClientName: string;
    extension: string;
};