/**
 * Map `items` through an async `fn` with at most `limit` calls in flight.
 *
 * Results come back in input order. The first rejection wins: in-flight
 * calls are allowed to settle, but no NEW items are claimed after a
 * failure, and the original error propagates to the caller. This mirrors
 * fail-fast sequential semantics — callers that want per-item error
 * tolerance catch inside `fn`.
 */
export declare function mapWithConcurrency<T, R>(items: readonly T[], limit: number, fn: (item: T, index: number) => Promise<R>): Promise<R[]>;