/** A letter with its marks, so a cut never parts `e` from the accent a decomposed `ệ` carries. */
export declare const LETTER: RegExp;
/** A type's extension: a dot and a short run of letters and figures, never a sentence's full stop. */
export declare const EXTENSION: RegExp;
/** A name's extension with its dot ("" for none) — never the whole name: a leading dot is a hidden file's name, not
 *  its type. A rename keeps it (`@lotics/shared/file_rename`'s rule, pinned by `file_rename_parity.test.ts`). */
export declare function filenameExtension(filename: string): string;
/**
 * A FILENAME AS THE HEAD A NARROW LINE CUTS AND THE TAIL IT NEVER DOES — the extension and the letters before it,
 * `TAIL` at least — so "seal-2024-contract.pdf" cut reads "seal-20…ct.pdf", never "seal-…".
 */
export declare function filenameEnds(filename: string): {
    head: string;
    tail: string;
};