/**
 * Generates the chart header line (e.g., "[CHART: Alice]", "[SYNASTRY: Alice-Bob]").
 * @param chartName The name of the chart or chart combination.
 * @param prefix The prefix for the header (e.g., "CHART", "SYNASTRY", "TRANSIT").
 * @returns An array containing a single string for the header line.
 */
export declare function generateChartHeaderOutput(chartName: string | undefined, prefix?: string): string[];