/**
 * Split a date interval into sub-intervals of `amount × unit`.
 *
 * - Returns an array of `{ start, end }` records that tile the interval.
 * - The final sub-interval is trimmed so its `end` never exceeds the original `end`.
 * - Returns `[{ start, end }]` when `start === end` (zero-length interval).
 * - Returns `[]` on invalid input (unparseable start/end, unsupported unit, non-positive amount,
 *   or a unit that has no effect on `PlainDate`, e.g. `"hours"`).
 * - Accepts GMT calendar-annotated PlainDate strings — E5 (issue #78). When `start` and `end`
 *   carry the *same* calendar tag, stepping (and each slice's boundaries) happens in that
 *   calendar — a Hebrew leap year splits into 13 month-slices, not 12 (E5 decision of record
 *   D5); otherwise (or if either is bare ISO) it falls back to Gregorian. Each boundary's tag is
 *   re-derived from the actual stepped date, never copied — a month-by-month step can cross a
 *   leap-month or era boundary mid-split.
 *
 * @param start ISO PlainDate string for the interval start, optionally calendar-annotated
 * @param end ISO PlainDate string for the interval end, optionally calendar-annotated
 * @param unit duration unit string — `"years" | "months" | "weeks" | "days"` (time units are ignored by PlainDate and return [])
 * @param amount positive number of units per step
 * @returns array of `{ start, end }` records, or [] on invalid input
 *
 * @example splitIntervalByUnitDate("2024-01-01", "2024-01-10", "day", 2) // [{ start: "2024-01-01", end: "2024-01-03" }, { start: "2024-01-03", end: "2024-01-05" }, { start: "2024-01-05", end: "2024-01-07" }, { start: "2024-01-07", end: "2024-01-09" }, { start: "2024-01-09", end: "2024-01-10" }]
 * @example splitIntervalByUnitDate("2024-01-01", "2024-01-09", "day", 2) // [{ start: "2024-01-01", end: "2024-01-03" }, { start: "2024-01-03", end: "2024-01-05" }, { start: "2024-01-05", end: "2024-01-07" }, { start: "2024-01-07", end: "2024-01-09" }]
 * @example splitIntervalByUnitDate("2024-01-01", "2024-01-01", "day", 2) // [{ start: "2024-01-01", end: "2024-01-01" }]
 * @example splitIntervalByUnitDate("2024-01-01", "2024-01-10", "day", 0) // []
 * @example splitIntervalByUnitDate("invalid", "2024-01-10", "day", 2) // []
 * @example splitIntervalByUnitDate("5784-01-01[u-ca=hebrew]", "5785-01-01[u-ca=hebrew]", "month", 1) // 13 slices, tiling the Hebrew leap year (including Adar I)
 */
export declare function splitIntervalByUnitDate(start: string, end: string, unit: string, amount: number): Array<{
    start: string;
    end: string;
}>;