export declare function hasInputSource(filePath?: string): boolean;
/**
 * Read JSON input from a file path or stdin.
 * - If filePath is a string (not '-'): reads from that file
 * - If filePath is '-' or undefined: reads from stdin
 * - If stdin is a TTY and no file: throws with usage hint
 */
export declare function readInput(filePath?: string): Promise<unknown>;