import type { CollectionReference, Firestore } from "@google-cloud/firestore";
import { type KeyOp } from "../../common/backend.js";
import type { FirestoreConfig } from "../types.js";
/**
 * Creates isLocked operation for Firestore backend.
 * Uses transactional cleanup with safety guard when enabled.
 * @see ../../common/time-predicates.ts for expiration logic
 */
export declare function createIsLockedOperation(db: Firestore, locksCollection: CollectionReference, config: FirestoreConfig): (opts: KeyOp) => Promise<boolean>;