/**
 * Read a JSON file, returning null if it doesn't exist or can't be parsed.
 */
export declare function readJSON<T>(filePath: string): Promise<T | null>;
/**
 * Atomically write a JSON file via tmp+rename. Optionally chmod to 0o600.
 */
export declare function writeJSONAtomic(filePath: string, value: unknown, options?: {
    chmod?: boolean;
}): Promise<void>;
/**
 * Create a simple promise-chain lock scoped to this module instance.
 * Returns { withLock } so each caller gets an independent lock.
 */
export declare function createLock(): <T>(fn: () => Promise<T>) => Promise<T>;