export interface PeriodInput {
    /** Last N days, counted from local midnight N-1 days ago through now. */
    days?: number;
    /** Just today, in local time. */
    today?: boolean;
    /** Explicit ISO 8601 bounds; override `days`/`today`. */
    since?: string;
    until?: string;
}
export interface Period {
    since?: string;
    until?: string;
    /** Human-readable description, e.g. "last 7 days (local time)". */
    label: string;
    /**
     * The comparable window immediately before this one, when one exists.
     *
     * Resolved HERE rather than derived later from `since`/`until`, for two
     * reasons. It is aligned to the same local midnights the period itself uses,
     * so `--days 7` compares against the seven whole days before -- not against
     * "the 156 hours before", which is what subtracting an open window's elapsed
     * length gives. And it is a pure function of the request, so two processes
     * answering the same question describe the same window rather than differing
     * by however many milliseconds apart they read the clock.
     *
     * Absent for "all time", which has no window before it.
     */
    previous?: {
        since: string;
        until: string;
        label: string;
    };
}
/**
 * Asked to compare against a window that does not exist.
 *
 * Its own class so the CLI can report it as the usage error it is -- one line
 * and exit 2, like any other bad flag combination -- rather than as an
 * unexpected failure with a stack trace.
 */
export declare class ComparePeriodError extends RangeError {
}
/**
 * Resolves a period. Day boundaries are LOCAL, because "today" means the user's
 * today; the stored timestamps are UTC and converted here rather than at query time.
 */
export declare function resolvePeriod(input?: PeriodInput): Period;