/** Active Threads — number of distinct thread IDs observed in agent runs.
 *  Uses approximate `count_distinct` (HyperLogLog on ClickHouse,
 *  `approx_count_distinct` on DuckDB) so the query stays fast even on
 *  tens of millions of rows. */
export declare function useActiveThreadsKpiMetrics(): import('@tanstack/react-query').UseQueryResult<{
    value: number | null;
    estimatedCost?: number | null | undefined;
    costUnit?: string | null | undefined;
    previousEstimatedCost?: number | null | undefined;
    costChangePercent?: number | null | undefined;
    previousValue?: number | null | undefined;
    changePercent?: number | null | undefined;
}, Error>;
