/**
 * ConcurrencyManager — enforces global and per-model concurrency limits
 * for background tasks.  Tasks that exceed the limit stay `pending` until
 * a running slot frees up.
 */
import type { BackgroundManager } from './manager';
export interface ConcurrencyLimits {
    maxConcurrent: number;
    perModelLimit: number;
}
export declare class ConcurrencyManager {
    private readonly bgManager;
    private readonly maxConcurrent;
    private readonly perModelLimit;
    constructor(bgManager: BackgroundManager, limits?: Partial<ConcurrencyLimits>);
    /**
     * Can a task with the given model start right now?
     * Checks both global running count and per-model running count.
     */
    canStart(model: string): boolean;
    /**
     * Try to promote as many pending tasks to running as the limits allow.
     * Returns the IDs of tasks that should be started.
     */
    drainPending(): string[];
    /** Current utilisation snapshot. */
    utilisation(): {
        running: number;
        pending: number;
        maxConcurrent: number;
        perModelLimit: number;
    };
}
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