/** Accepted scalar values for a URL query parameter. */
export type QueryParamValue = string | number | boolean | undefined | null;
/**
 * Builds a URL query string from a flat key→value map.
 * Entries with `undefined` or `null` values are omitted.
 * Returns a string that starts with `"?"` when non-empty, or `""` when all values were omitted.
 *
 * @example
 * buildQueryString({ limit: 10, offset: undefined, subject: "hello" })
 * // => "?limit=10&subject=hello"
 */
export declare function buildQueryString(params: Record<string, QueryParamValue>): string;