export interface GspRegion {
    gsp_id: string;
    gsp_name: string;
    region_id: string;
    region_name: string;
}
export interface GspLookupResult extends GspRegion {
    distance_km: number;
}
/**
 * Find the nearest GSP to a given lat/lon using haversine distance.
 * Returns the nearest GSP within `radiusKm` (default 50), or null if none found.
 *
 * This is a nearest-GSP approximation, not polygon containment.
 */
export declare function lookupGspRegion(lat: number, lon: number, radiusKm?: number): Promise<GspLookupResult | null>;
/** Reset cache — exposed for tests. */
export declare function resetGspCacheForTests(): void;