import type { MapMarkerData } from './map-marker';
export interface MapClusterConfig {
    /**
     * Groups markers by a key you derive — a municipality, a unit, a case number.
     * Records sharing a key collapse into one marker carrying a count.
     */
    by?: (marker: MapMarkerData, index: number) => string;
    /** Above this zoom the cluster splits back into individual markers. */
    maxZoom?: number;
    /**
     * Proximity threshold in pixels. Markers closer than this merge even when
     * `by` did not group them. Requires a projection to be meaningful.
     */
    radiusPx?: number;
}
/** A marker that stands for several records. */
export interface MapClusterResult {
    /** The marker to render — either the original, or a synthesized cluster. */
    marker: MapMarkerData;
    /** Indices into the source array that this marker represents. */
    memberIndices: number[];
}
/**
 * Collapses co-located records into counted markers.
 *
 * @description
 * Several records at the same position used to draw several pins on top of each
 * other, which reads as one point and undercounts the data. A cluster carries a
 * `badge` with the number it stands for.
 *
 * This is also the anonymization hook: `minAggregation` forces grouping whenever
 * a group holds fewer than N records, so a single individual is never exposed as
 * an isolated point. That is **display** anonymization — it changes what the
 * screen shows, not what the payload contains. Coordinates precise enough to
 * identify someone must be withheld server-side; this cannot do that for you.
 *
 * @param minAggregation - Groups smaller than this are merged into the nearest
 *   remaining group rather than plotted individually. `0` disables it.
 */
export declare function clusterMarkers(markers: MapMarkerData[], cluster: MapClusterConfig | undefined, minAggregation?: number): MapClusterResult[];