export interface HarnessMetric {
    avg_cost_usd: number | null;
    avg_duration_ms: number | null;
    samples: number;
    /**
     * Auth route the harness's LAST settled attempt actually ran under
     * (adapter-disclosed route evidence, not a manifest capability guess).
     * Economy routing may consume settled cost as evidence; no quality prior is
     * inferred. Null until any attempt disclosed a route.
     */
    last_auth_mode: "local_session" | "api_key" | null;
}
export type HarnessMetrics = Record<string, HarnessMetric>;
export declare function metricsPath(configDir: string): string;
export declare function loadHarnessMetrics(configDir: string): HarnessMetrics;
/**
 * Record one settled attempt (EMA update; atomic tmp+rename write).
 * `authMode` is route evidence and updates independently of the performance
 * sample: an auth-only record (no cost/duration) refreshes `last_auth_mode`
 * WITHOUT counting a sample, so errored attempts can still disclose the route
 * they burned without earning a flattering latency average.
 * An explicit null cost means the settled attempt was unpriced and invalidates
 * the prior cost average; an omitted cost leaves compatible history unchanged.
 */
export declare function recordHarnessMetric(configDir: string, harnessId: string, sample: {
    costUsd?: number | null;
    durationMs?: number | null;
    authMode?: "local_session" | "api_key" | null;
}): void;
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