/**
 * @file metrics.service.ts
 * @description Core service backing the `/metrics` endpoint (issue #397).
 */
import type { MetricsOptionsInterface } from '../common';
interface CounterSnapshotEntry {
    name: string;
    count: number;
    attributes: Record<string, string>;
}
interface GaugeSnapshotEntry {
    name: string;
    value: number;
    attributes?: Record<string, string>;
    help?: string;
}
interface ProcessStatsCollector {
    collect(): GaugeSnapshotEntry[];
}
/**
 * Lazily build a `ProcessStatsCollector` when the metrics config selects the
 * `process` category (or omits `include` entirely, which means "every
 * category"). Returns `undefined` when process metrics are filtered out so
 * the per-scrape `process.cpuUsage()` / `monitorEventLoopDelay()` calls don't
 * run for nothing.
 *
 * Uses the same lazy `require('@frontmcp/observability')` as the snapshot
 * source so the SDK ↔ observability import cycle stays broken at module
 * init.
 */
export declare function createProcessStatsCollectorIfEnabled(config: MetricsOptionsInterface): ProcessStatsCollector | undefined;
/**
 * Resolved metrics body + content type, returned by `getMetrics()`.
 */
export interface MetricsResponse {
    contentType: string;
    body: string;
}
/**
 * Test-injection seam for the counter snapshot source — production callers
 * never set this.
 */
export interface MetricsServiceOptions {
    snapshotSource?: () => CounterSnapshotEntry[];
}
export declare class MetricsService {
    private readonly config;
    private readonly processCollector?;
    private readonly snapshotSource;
    private readonly resolvedToken?;
    constructor(config: MetricsOptionsInterface, processCollector?: ProcessStatsCollector, options?: MetricsServiceOptions);
    /**
     * Render the current metrics scrape in the configured format.
     */
    getMetrics(): MetricsResponse;
    /**
     * Check the supplied `Authorization` header against the configured auth
     * policy. Returns the HTTP status the route should respond with:
     *   - 200 — the request is allowed to read metrics
     *   - 401 — missing credentials when token auth is configured
     *   - 403 — wrong credentials
     */
    authorize(authorizationHeader: string | undefined): 200 | 401 | 403;
}
export {};
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