import { type GatewayModelTarget } from "./types.js";
export type GatewayMetricOutcome = "success" | "error" | "cancelled" | "cache";
export interface GatewayMetricsSnapshot {
    inFlight: number;
    sampleCount: number;
    successes: number;
    errors: number;
    cancellations: number;
    p50LatencyMs?: number;
    p95LatencyMs?: number;
    p95TtftMs?: number;
    p50TokensPerSecond?: number;
    lastCompletedAt?: number;
}
export interface GatewayMetricsHandle {
    firstText(): void;
    end(outcome: GatewayMetricOutcome, outputTokens?: number): void;
}
export interface GatewayMetricsStore {
    begin(target: GatewayModelTarget): GatewayMetricsHandle | undefined;
    snapshot(target: GatewayModelTarget): GatewayMetricsSnapshot | undefined;
}
export interface GatewayMetricsOptions {
    windowMs?: number;
    maxTargets?: number;
    maxSamplesPerTarget?: number;
    now?: () => number;
}
/** Bounded, process-local metrics. New targets are untracked while every capacity slot is active. */
export declare const createGatewayMetrics: (options?: GatewayMetricsOptions) => GatewayMetricsStore;
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