import { CollectionSubscription } from '../../collection/subscription.js';
import { LazyDemandPlan } from '../compiler/joins.js';
export type DemandUpdate = {
    changed: boolean;
    empty: boolean;
    ready: Promise<void> | true;
};
/**
 * Keeps lazy subset requests aligned with the current relation of demanded
 * keys. Additions load only new coverage. Removals release and rebuild only
 * request segments that covered a removed key.
 */
export declare class SubsetDemandController {
    private readonly states;
    private readonly warnedPlans;
    setDemand(subscription: CollectionSubscription, plan: LazyDemandPlan, keys: Set<unknown>): DemandUpdate;
    clear(): void;
    private warnUnoptimized;
}