/**
 * File-based locking for state.json.
 *
 * Uses atomic mkdir() as the lock primitive (works across platforms).
 * Includes stale-lock detection: if the lock is older than STALE_MS
 * and the holding PID is dead, it's forcibly removed.
 *
 * Lock directory is passed in via setLockDir() from state.ts after initStateDir().
 */
/** Called by state.ts after initStateDir() to set the lock directory. */
export declare function setLockDir(dir: string): void;
/**
 * Execute `fn` while holding the state lock.
 * Handles stale lock cleanup and retries with backoff.
 */
export declare function withStateLock<T>(fn: () => Promise<T>): Promise<T>;