export interface SectionNavHandle<K extends string> {
    /** The scroller or any box inside it; the hook finds the nearest scrolling ancestor, so a surface that
     *  does not own its scroller hands its root. */
    scrollRef: (node: HTMLElement | null) => void;
    /** The section the scroll sits in (the rail item's `current`); none without sections. */
    activeKey: K | undefined;
    /** The reader has left the head — scrolled, or jumped: a rail marking the work's step marks the reader's place
     *  from then on, so at the head one item stands out. */
    moved: boolean;
    /** `ref={register(key)}` on each section's heading, the jump target and spy's measure; stable per key,
     *  so re-renders never re-attach. */
    register: (key: K) => (node: HTMLElement | null) => void;
    /** The reader's jump, smooth, and the only scroll this hook makes: a section near the end lands as far as
     *  the content reaches, since padding the surface to seat it at the top moves the scroll the reader is
     *  making. */
    jumpTo: (key: K) => void;
}
/** Scroll-spy for a long surface with an outline rail: sections register headings, the rail jumps to them,
 *  and `activeKey` follows the scroll. Pass keys in page order. Jump and highlight read live DOM
 *  positions, so async growth above never stales them; an unmounted section keeps its last offset. It only
 *  reads the scroll, never moves it unasked. `inset` is the px a sticky band (a phone's section strip)
 *  covers at the scroller's top: a jump lands under it, and the spy's line moves down by it. */
export declare function useSectionNav<K extends string>(keys: readonly K[], inset?: number): SectionNavHandle<K>;