/**
 * Lightweight in-process metrics registry with zero external dependencies.
 *
 * Provides counters, gauges, and bucketed histograms for operational
 * observability of the dispatch subsystem. No HTTP server — snapshots are
 * consumed programmatically or exposed via other means (e.g., health check).
 *
 * Gated via ROLEBOX_METRICS env var. When unset or falsy, all methods are
 * NO-OPs and snapshot() returns an empty structure.
 */
export interface CounterSnapshot {
    value: number;
    labels?: Record<string, string>;
}
export interface GaugeSnapshot {
    value: number;
    labels?: Record<string, string>;
}
export interface HistogramSnapshot {
    buckets: Record<string, number>;
    sum: number;
    count: number;
    labels?: Record<string, string>;
}
export interface MetricsSnapshot {
    counters: Record<string, CounterSnapshot>;
    gauges: Record<string, GaugeSnapshot>;
    histograms: Record<string, HistogramSnapshot>;
}
/**
 * A monotonically increasing counter.
 *
 * Labels must be low-cardinality only (agent id, status, concurrency key).
 * Do NOT use high-cardinality labels like taskId or sessionId.
 */
export declare class Counter {
    private _value;
    inc(n?: number): void;
    peek(): number;
}
/**
 * A gauge that can go up and down.
 *
 * Same low-cardinality label constraint as Counter.
 */
export declare class Gauge {
    private _value;
    inc(n?: number): void;
    dec(n?: number): void;
    set(val: number): void;
    peek(): number;
}
/**
 * A histogram with fixed, named bucket boundaries (milliseconds).
 *
 * Buckets consume bounded memory regardless of observation count:
 * only the 11 predefined buckets are tracked.
 *
 * Labels must be low-cardinality only (agent id, status, concurrency key).
 * Do NOT use high-cardinality labels like taskId or sessionId.
 */
export declare class Histogram {
    private _buckets;
    private _sum;
    private _count;
    constructor();
    observe(value: number): void;
    peek(): HistogramSnapshot;
}
/**
 * In-process metrics registry.
 *
 * Creates counters, gauges, and histograms keyed by `name` + sorted labels
 * so that label sets like `{status: "ok"}` and `{status: "fail"}` produce
 * distinct metrics under the same name.
 *
 * When `enabled` is false (default: read from ROLEBOX_METRICS env var),
 * all metric creation returns NO-OP wrappers and snapshot() returns an
 * empty structure.
 */
export declare class MetricsRegistry {
    private readonly enabled;
    private counters;
    private gauges;
    private histograms;
    private coreCounters;
    private coreGauges;
    constructor(enabled?: boolean);
    counter(name: string, labels?: Record<string, string>): Counter;
    gauge(name: string, labels?: Record<string, string>): Gauge;
    histogram(name: string, labels?: Record<string, string>): Histogram;
    snapshot(): MetricsSnapshot;
    reset(): void;
}
/** Module-level metrics registry. Gated via ROLEBOX_METRICS env var. */
export declare const metrics: MetricsRegistry;
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