export type RowScrollScaling = {
    /** True when the true content height exceeds the cap and mapping applies. */
    readonly active: boolean;
    /** Height (px) the DOM scroll spacer should occupy - capped at maxDomHeight. */
    readonly domTotal: number;
    /** Map a DOM scrollTop into the virtualizer's logical scroll offset. */
    domToLogical(domTop: number): number;
    /** Map a virtualizer logical offset back into a DOM scrollTop. */
    logicalToDom(logical: number): number;
};
/**
 * Resolve the usable max element height from the two raw DOM signals.
 *
 * `layoutCap` is a tall probe's clamped `offsetHeight` - the height layout
 * assigns the element. `scrollCap` is the `scrollHeight` a real `overflow:auto`
 * container exposes for that same probe - the height the user can actually
 * scroll through. They differ on mobile / high-DPR engines, which report a
 * generous `offsetHeight` but then expose a SMALLER scrollable range (the
 * physical limit is in device px, so a 3x-DPR phone has ~1/3 the CSS-px scroll
 * cap). Trusting `offsetHeight` alone is exactly what strands the last rows of
 * a huge grid on a phone, so we take the smaller of the two.
 *
 * A junk reading (<= the sanity floor, or so large the browser clearly didn't
 * clamp) is dropped; if neither signal survives, the caller's conservative
 * `fallback` is returned unchanged.
 */
export declare function resolveMaxDomHeight(layoutCap: number, scrollCap: number, fallback: number): number;
/**
 * Build the scaling mapping for one axis.
 *
 * @param trueTotal     The real content height in logical px (count * rowH, or
 *                      the cumulative offset total for variable rows).
 * @param maxDomHeight  The browser's max element height (detected at runtime).
 * @param viewport      The scroll viewport height in px.
 *
 * Invariants (verified in scroll-scaling.test.ts):
 *  - Inert when `trueTotal <= maxDomHeight`: both maps are the identity.
 *  - `domTotal <= maxDomHeight` always, so the spacer never exceeds the cap.
 *  - Endpoints line up: domTop 0 -> logical 0, and the DOM max
 *    (`domTotal - viewport`) -> the logical max (`trueTotal - viewport`), so
 *    the very last row is always reachable.
 *  - `logicalToDom` is the inverse of `domToLogical` across the range.
 *  - Both maps are monotonic non-decreasing and clamp out-of-range inputs.
 */
export declare function createRowScrollScaling(trueTotal: number, maxDomHeight: number, viewport: number): RowScrollScaling;