/**
 * Prometheus Metrics
 *
 * Proper Prometheus exposition format. Auto-tracks:
 *
 *   forge_http_request_duration_seconds  — histogram, per route + status + tenant
 *   forge_http_requests_total            — counter, per route + status + tenant
 *   forge_http_active_requests           — gauge, current in-flight
 *   forge_rpc_duration_seconds           — histogram, per target + method
 *   forge_rpc_total                      — counter, per target + method + success/error
 *   forge_circuit_breaker_state          — gauge, 0=closed 1=open 2=half-open
 *   forge_concurrency_limit              — gauge, per-service adaptive limit
 *   forge_concurrency_in_flight          — gauge, per-service in-flight
 *   forge_ws_connections_active          — gauge, current WebSocket connections
 *   forge_ws_messages_total              — counter, WebSocket messages
 *   forge_event_loop_lag_seconds         — gauge with percentiles (p50, p95, p99)
 *
 * GET /metrics → text/plain Prometheus format
 *
 * Usage:
 *   const metrics = new PrometheusMetrics('users', 0);
 *   metrics.httpRequestDuration(0.045, { method: 'GET', path: '/users/:id', status: 200, tenant_id: 't_acme' });
 *   metrics.expose() → "# HELP forge_http_request_duration_seconds ..."
 */
import { monitorEventLoopDelay } from "node:perf_hooks";
interface ErrorLike {
    code?: string;
    statusCode?: number;
}
type LabelValue = string | number | boolean | null | undefined;
interface Labels {
    [key: string]: LabelValue;
}
interface HistogramEntry {
    count: number;
    sum: number;
    buckets: number[];
    bucketBounds: number[];
}
/** P2: Normalize error codes to a finite set to prevent cardinality bombs */
export declare function normalizeErrorCode(err: ErrorLike): string;
export declare class PrometheusMetrics {
    serviceName: string;
    workerId: number;
    startTime: number;
    httpBuckets: number[];
    rpcBuckets: number[];
    _counters: Map<string, number>;
    _gauges: Map<string, number>;
    _histograms: Map<string, HistogramEntry>;
    _eventLoopMonitor: ReturnType<typeof monitorEventLoopDelay> | null;
    constructor(serviceName: string, workerId: number);
    httpRequestStart(): void;
    httpRequestEnd(durationSecs: number, labels?: Labels): void;
    rpcCall(durationSecs: number, labels?: Labels): void;
    wsConnectionOpen(): void;
    wsConnectionClose(): void;
    wsMessage(direction?: string): void;
    concurrencyUpdate(target: string, limit: number, inFlight: number): void;
    circuitBreakerState(target: string, state: string): void;
    counter(name: string, value?: number, labels?: Labels): void;
    gauge(name: string, value: number, labels?: Labels): void;
    histogram(name: string, value: number, labels?: Labels, buckets?: number[]): void;
    /**
     * Render all metrics in Prometheus text exposition format.
     */
    expose(): string;
    _labelStr(labels: Labels): string;
    _counterInc(name: string, labels?: Labels, value?: number): void;
    _gaugeSet(name: string, value: number, labels?: Labels): void;
    _gaugeInc(name: string, labels?: Labels): void;
    _gaugeDec(name: string, labels?: Labels): void;
    _histogramObserve(name: string, value: number, labels: Labels | undefined, buckets: number[]): void;
    /**
     * OPS-8: Cleanup event loop monitor when metrics instance is no longer needed
     */
    cleanup(): void;
}
export {};
//# sourceMappingURL=Prometheus.d.ts.map