/**
 * Scrollbar math and card-span geometry — pure functions for thumb position,
 * track-cell-to-offset mapping, and mounted card viewport spans.
 *
 * Extracted from scrollable-history.tsx.
 */
import type { EntryHeightCache } from '../../height-cache.js';
import { type RenderGroup } from './tool-group.js';
/** Pure thumb geometry for the scrollbar: where the thumb starts and how many
 *  cells it spans, given the track height, scroll offset, and total content
 *  height. Exported for testing. */
export declare function scrollbarThumb(rows: number, offset: number, total: number): {
    top: number;
    size: number;
    scrollable: boolean;
};
/** Inverse of {@link scrollbarThumb}: given a clicked/dragged 0-based cell on a
 *  track of `rows` height, return the scroll offset (rows up from the bottom)
 *  that lands the visible window there. Cell 0 (top) → oldest content (max
 *  offset); cell rows-1 (bottom) → newest (offset 0). Exported for testing. */
export declare function scrollOffsetForTrackRow(rows: number, total: number, cell: number): number;
/**
 * Per-card viewport span for the currently-mounted groups. Mirrors
 * {@link buildCopyRegistry}'s visibleClip math so the drag-select gesture asks
 * the same geometry question the copy-hit registry already answers.
 */
export interface MountedCardSpan {
    entryId: number;
    /** 0-based viewport row of the first VISIBLE row of the card. */
    viewportStartRow: number;
    /** 0-based viewport row one past the last VISIBLE row of the card. */
    viewportEndRow: number;
    /** Card's geometry in rows; visibleClip + scrolled-clip aware. */
    totalRows: number;
    entryIds?: readonly number[];
}
/**
 * Build per-card viewport spans for every mounted render group. Pure — given
 * the same render-group list, height cache, scroll state, and viewport size,
 * the result is deterministic and matches the copy-hit registry. Exported so
 * tests can verify the span map without mounting the full component.
 */
export declare function buildMountedCardSpans(opts: {
    renderGroups: readonly RenderGroup[];
    heightCache: EntryHeightCache;
    scrolled: boolean;
    clip: number;
    tailRows: number;
    viewportRows: number;
    showModelReasoning?: boolean | undefined;
}): MountedCardSpan[];
/**
 * Find the card whose viewport row range contains `row`. Pure.
 * Returns null when the row is in a blank gap or outside the viewport.
 */
export declare function selectionHitAt(row: number, spans: readonly MountedCardSpan[]): {
    entryId: number;
    entryIds?: readonly number[];
} | null;
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