/**
 * @file Generate a unique filepath by appending `-1`, `-2`, … before the
 *   extension until the path is free. Useful for "save next to existing" flows
 *   where overwriting silently would be wrong (PDF reports, exports, etc.).
 */
import type { PathLike } from 'node:fs';
/**
 * Generate a unique filepath by adding number suffix if the path exists.
 * Appends `-1`, `-2`, etc. before the file extension until a non-existent path
 * is found. Useful for creating files without overwriting existing ones.
 *
 * @example
 *   ;```ts
 *   // If 'report.pdf' exists, returns 'report-1.pdf'
 *   const uniquePath = uniqueSync('./report.pdf')
 *
 *   // If 'data.json' and 'data-1.json' exist, returns 'data-2.json'
 *   const path = uniqueSync('./data.json')
 *
 *   // If 'backup' doesn't exist, returns 'backup' unchanged
 *   const backupPath = uniqueSync('./backup')
 *   ```
 *
 * @param filepath - Desired file path.
 *
 * @returns Normalized unique filepath (original if it doesn't exist, or with
 *   number suffix)
 */
export declare function uniqueSync(filepath: PathLike): string;
