/**
 * Metrics Collection
 *
 * Counters and histograms for observability.
 */
import type { MetricStats } from './types.js';
export declare class Metrics {
    private counters;
    private histograms;
    private gauges;
    /**
     * Increment a counter.
     */
    increment(name: string, value?: number): void;
    /**
     * Decrement a counter.
     */
    decrement(name: string, value?: number): void;
    /**
     * Record a value in a histogram.
     */
    histogram(name: string, value: number): void;
    /**
     * Set a gauge value.
     */
    gauge(name: string, value: number): void;
    /**
     * Get a counter value.
     */
    getCounter(name: string): number;
    /**
     * Get a gauge value.
     */
    getGauge(name: string): number;
    /**
     * Get histogram statistics.
     */
    getHistogramStats(name: string): MetricStats | null;
    /**
     * Get all metrics.
     */
    getAll(): {
        counters: Record<string, number>;
        gauges: Record<string, number>;
        histograms: Record<string, MetricStats | null>;
    };
    /**
     * Reset all metrics.
     */
    reset(): void;
    /**
     * Reset a specific metric.
     */
    resetMetric(name: string): void;
    /**
     * Export metrics as Prometheus-style text.
     */
    toPrometheus(): string;
    /**
     * Calculate percentile from sorted array.
     */
    private percentile;
}
/**
 * Get or create global metrics instance.
 */
export declare function getMetrics(): Metrics;
/**
 * Create a new metrics instance.
 */
export declare function createMetrics(): Metrics;
export declare const METRIC_NAMES: {
    readonly REQUESTS_STARTED: "requests.started";
    readonly REQUESTS_SUCCESS: "requests.success";
    readonly REQUESTS_FAILURE: "requests.failure";
    readonly REQUESTS_TIMEOUT: "requests.timeout";
    readonly REQUESTS_CIRCUIT_BLOCKED: "requests.circuit_breaker_blocked";
    readonly REQUEST_DURATION_MS: "requests.duration_ms";
    readonly SPAWN_DURATION_MS: "spawn.duration_ms";
    readonly PROCESSES_ACTIVE: "processes.active";
    readonly PROCESSES_SPAWNED: "processes.spawned";
    readonly PROCESSES_KILLED: "processes.killed";
    readonly ERRORS_AUTH: "errors.auth";
    readonly ERRORS_RATE_LIMIT: "errors.rate_limit";
    readonly ERRORS_TIMEOUT: "errors.timeout";
    readonly ERRORS_NETWORK: "errors.network";
    readonly ERRORS_UNKNOWN: "errors.unknown";
    readonly RETRIES_ATTEMPTED: "retries.attempted";
    readonly RETRIES_SUCCESS: "retries.success";
};
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