/**
 * src/core/ConcurrencyQueue.ts
 *
 * Priority queue manager for the Society. Ensures work is prioritised, slots
 * are respected, and no request starves.
 *
 * Implements docs/architecture/concurrency-and-queues.md:
 * - Priority levels: USER (2), SCHEDULED (1), BACKGROUND (0)
 * - Configurable slots (default 3, max 10)
 * - Queue depth cap = 10× slots
 * - Starvation escalation at 60s
 * - USER-displacement when queue is full
 */
export type Priority = 'USER' | 'SCHEDULED' | 'BACKGROUND';
export interface QueuedTask {
    id: string;
    label: string;
    priority: Priority;
    priorityValue: number;
    enqueuedAt: number;
    execute: () => Promise<void>;
}
export interface QueueStatus {
    running: number;
    queued: number;
    paused: number;
    slotsTotal: number;
}
export declare class ConcurrencyQueue {
    private queue;
    private running;
    private paused;
    private slotCount;
    private readonly maxDepth;
    private readonly starvationMs;
    private timerId;
    constructor(slots?: number, starvationMs?: number);
    /**
     * Enqueue a task for execution. Returns true if the task was accepted,
     * false if it was rejected (BACKGROUND when queue full).
     *
     * Throws if the queue is full and the request cannot be admitted even
     * via displacement.
     */
    enqueue(task: QueuedTask): boolean;
    /** Process the next task if a slot is available. */
    private tryProcess;
    private execute;
    /**
     * Displace the lowest-priority item from the queue to make room for
     * a USER request.
     */
    private displaceLowestPriority;
    /**
     * Starvation prevention: boost priority of tasks that have been waiting
     * longer than the threshold. Call periodically or automatically.
     */
    private checkStarvation;
    /** Start the starvation checker background timer. */
    start(): void;
    /** Stop the starvation checker. */
    stop(): void;
    getStatus(): QueueStatus;
    statusLine(): string;
}
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