/**
 * Atomically write `data` to `filePath` (async).
 *
 * Writes to a temp file then renames it into place. On any failure the temp
 * file is removed and the error is re-thrown so callers can handle it.
 */
export declare function atomicWriteFile(filePath: string, data: string): Promise<void>;
/**
 * Atomically write `data` to `filePath` (sync).
 *
 * Sync variant for callers that cannot await. Same temp-file-then-rename
 * strategy as {@link atomicWriteFile}.
 */
export declare function atomicWriteFileSync(filePath: string, data: string): void;