/**
 * Right-edge rail for the managed viewport. Its first column is the copy icon
 * (or blank), the second is a visual gap, and the third is the scrollbar track.
 * All three columns are always reserved, so copy affordances and scrollability
 * never reflow chat content.
 *
 * The gap column doubles as the drag-selection highlight band: while a drag is
 * in progress, the subscribing component re-renders ONLY this rail (via
 * useSyncExternalStore on {@link SelectionBandStore}) — the history cards
 * never re-render, and because the band occupies the already-reserved gap
 * column the layout (and the fixed-height overflow-hidden viewport) cannot
 * change mid-drag.
 *
 * Extracted from scrollable-history.tsx.
 */
import type React from 'react';
import type { CopyHit } from './copy-geometry.js';
import { type SelectionBandStore } from './selection-band-store.js';
export declare function Scrollbar({ rows, offset, total, copyHits, copiedEntryId, selectionBandStore, }: {
    rows: number;
    offset: number;
    total: number;
    copyHits: readonly CopyHit[];
    copiedEntryId?: number | null | undefined;
    selectionBandStore?: SelectionBandStore | undefined;
}): React.ReactElement;
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