import type { MetricSpread } from "./multirun.js";
/**
 * Baselines for "did that change actually help" comparisons, persisted under
 * ~/.pagespeed-mcp/baselines.json keyed by url+strategy. The first call on a
 * URL records the baseline; later calls compare against it. Verdicts are only
 * given where the two min-max ranges do NOT overlap — comparing medians alone
 * reports improvements that are just the instrument moving.
 */
interface Snapshot {
    recorded: string;
    lighthouseVersion?: string;
    scores: Record<string, MetricSpread>;
    metrics: Record<string, MetricSpread>;
}
export declare function getBaseline(url: string, strategy: string): Snapshot | null;
export declare function saveBaseline(url: string, strategy: string, multirun: {
    stats: any;
    scores: Record<string, MetricSpread | null>;
    metrics: Record<string, MetricSpread | null>;
}, lighthouseVersion?: string): Snapshot;
export declare function clearBaseline(url: string, strategy: string): void;
export interface RangeVerdict {
    metric: string;
    before: MetricSpread;
    after: MetricSpread;
    verdict: "improved" | "regressed" | "no-verdict";
    medianDelta: number;
    guaranteedDelta: number;
}
/**
 * Compare two snapshots. A verdict is only given where the ranges are
 * completely disjoint; `guaranteedDelta` is the smaller figure the gap
 * actually guarantees (max(before.min - after.max, 0) style) and is the one
 * to quote.
 */
export declare function compareBaselines(before: Snapshot, after: Snapshot): RangeVerdict[];
export {};