/**
 * Returns the in-flight request for `key`, or starts and tracks a new one.
 *
 * Settled requests are removed only when they are still the request registered
 * for the key, so an older request cannot delete a newer replacement.
 *
 * @param requests - In-flight requests indexed by their logical operation
 * @param key - Stable identity for the operation
 * @param createRequest - Starts the operation when no request is in flight
 * @returns The existing or newly tracked request
 */
export declare function coalesceInFlight<Result>(requests: Map<string, Promise<Result>>, key: string, createRequest: () => Promise<Result>): Promise<Result>;