export type Release = () => void;
/**
 * Shared by run_agent and run_workflow so one global cap bounds all subagents. Released
 * slots pass directly to FIFO waiters, preventing tryAcquire() from claiming a
 * slot during an asynchronous handoff and exceeding the cap.
 */
export declare class ConcurrencyLimiter {
    readonly max: number;
    private active;
    private readonly waiters;
    constructor(max: number);
    get activeCount(): number;
    get pendingCount(): number;
    /** Acquires synchronously without blocking, or returns null at capacity. */
    tryAcquire(): Release | null;
    /** Acquires a slot or queues until one is available; rejects if aborted. */
    acquire(signal?: AbortSignal): Promise<Release>;
    private makeRelease;
    private handOffOrDecrement;
}