/**
 * Burst policy, detects rapid notification floods within a short observation
 * window and collapses them into a batch group key.
 *
 * Unlike the rolling BatchPolicy (which uses a fixed time window), the burst
 * policy measures the event rate within a sliding observation window and
 * activates only when the rate exceeds a configured threshold. Once activated,
 * subsequent notifications in the group are collapsed until the burst subsides.
 *
 * A burst group key is `{domain}:{level}`, matching the BatchPolicy scheme
 * so downstream consumers can coalesce both batch types uniformly.
 */
import type { Notification } from '../types.js';
/**
 * BurstPolicy tracks notification arrival rates per domain:level group and
 * activates burst suppression when the rate exceeds the threshold.
 */
export declare class BurstPolicy {
    /** Active burst group entries keyed by `{domain}:{level}`. */
    private readonly groups;
    /** Observation window in ms. */
    private readonly observationWindowMs;
    /** Number of events within the window before burst activates. */
    private readonly burstThreshold;
    /** Cooldown in ms after last event before the burst group resets. */
    private readonly cooldownMs;
    constructor(observationWindowMs?: number, burstThreshold?: number, cooldownMs?: number);
    /**
     * Builds the burst group key for a notification.
     *
     * @param notification - The notification to key.
     * @returns A string key in the form `{domain}:{level}`.
     */
    private buildKey;
    /**
     * Prune timestamps outside the current observation window.
     */
    private pruneWindow;
    /**
     * Evaluates a notification against the burst policy.
     *
     * @param notification - Incoming notification to evaluate.
     * @returns The burst group key if the notification is being burst-collapsed,
     *          or undefined if it should proceed to the next policy stage.
     */
    evaluate(notification: Notification): string | undefined;
    /**
     * Returns the number of notifications collapsed in a burst group.
     *
     * @param key - The burst group key (`{domain}:{level}`).
     * @returns The collapsed count, or 0 if no group exists.
     */
    getCollapsedCount(key: string): number;
    /**
     * Resets a specific burst group, clearing its state.
     * Call this when the burst window expires and the group is ready to
     * surface its summary.
     *
     * @param key - The burst group key to reset.
     */
    resetGroup(key: string): void;
    /**
     * Returns all currently active burst group keys.
     *
     * Callers can use this to surface summary notifications for each active
     * burst group at flush time.
     */
    getActiveGroups(): string[];
}
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