/** Append a timestamped line to the log file. */
export declare function logToFile(message: string): Promise<void>;
/** Rotate log if over size limit. Keeps one previous (.1) file. */
export declare function rotateLogIfNeeded(): Promise<void>;
/** Open a file descriptor for the log (for spawn stdio redirect). Caller must closeSync(fd). */
export declare function openLogFd(): number;