/**
 * OOXML `t` attribute values. Note that 'inlineStr' is treated
 * separately — the writer chooses between 's' (shared string) and
 * 'inlineStr' based on workbook settings, not the value itself.
 */
export type CellDataType = 'n' | 's' | 'b' | 'd' | 'f' | 'e';
/** Excel error tokens. Anything outside this set is treated as a string. */
export declare const ERROR_CODES: ReadonlySet<string>;
/**
 * Infer the cell `t` attribute for a runtime value.
 *
 * - `boolean` → 'b'
 * - `number` → 'n' (incl. integer numerics; date inference is left to
 *   the caller because Excel decides on type via the cell's number
 *   format, not the raw value)
 * - `Date` → 'd'
 * - string starting with `=` → 'f' (formula)
 * - string in {@link ERROR_CODES} → 'e'
 * - any other string → 's'
 * - `null` / `undefined` → 'n' (empty)
 *
 * Throws nothing — returns 'n' as the no-information fallback.
 */
export declare function inferCellType(value: unknown): CellDataType;