/**
 * Pure metric folding for dsh-eval: one pass over a session trace produces
 * the automatic metric set, and pricing converts provider token buckets into
 * USD. The fold mirrors session-stats wall-time semantics and adds the
 * eval-owned failure and retry counters.
 *
 * @module dsh-eval/metrics
 */
import type { SessionEvent } from '@deepseek-ai/dsh-session';
import type { BenchmarkPricing, EvalCaseMetrics, EvalTokenUsage } from './types.ts';
/**
 * Fold a session trace into automatic metrics without pricing.
 * @param events - the trace's durable events in log order.
 * @returns the folded metrics with `costUsd: null`.
 */
export declare function foldMetrics(events: readonly SessionEvent[]): EvalCaseMetrics;
/**
 * Convert token buckets into USD using per-million-token prices.
 * @param tokens - summed token buckets.
 * @param pricing - per-million-token USD prices.
 * @returns the estimated cost in USD.
 */
export declare function computeCost(tokens: EvalTokenUsage, pricing: BenchmarkPricing): number;
/**
 * Fold metrics and attach cost when a pricing table entry exists.
 * @param events - the trace's durable events in log order.
 * @param pricing - the benchmark model's pricing, or undefined for no cost.
 * @returns the folded metrics.
 */
export declare function computeMetrics(events: readonly SessionEvent[], pricing: BenchmarkPricing | undefined): EvalCaseMetrics;
/**
 * Aggregate per-trial metrics: arithmetic means for counts and wall times,
 * pooled success rate, and the mean cost when every trial priced it.
 * @param items - completed trials' metrics.
 * @returns the aggregate, or null when no trial is included.
 */
export declare function aggregateMetrics(items: readonly EvalCaseMetrics[]): EvalCaseMetrics | null;