/**
 * Performance metrics collector — captures Core Web Vitals and navigation timing
 * for pages visited during crawl runs.
 * Collects LCP, CLS, INP, TTFB, long tasks, and slow resources via PerformanceObserver
 * and the Navigation/Resource Timing APIs.
 */
import type { Page } from 'playwright';
export type CwvScore = 'good' | 'needs-improvement' | 'poor';
export interface LcpMetric {
    value: number;
    score: CwvScore;
    elementTag: string | null;
    url: string | null;
}
export interface ClsMetric {
    value: number;
    score: CwvScore;
    shiftCount: number;
}
export interface InpMetric {
    p75: number;
    score: CwvScore;
    sampleCount: number;
}
export interface NavTimingMetric {
    ttfb: number;
    ttfbScore: CwvScore;
    domContentLoaded: number;
    domComplete: number;
    loadComplete: number;
    transferSizeBytes: number;
    protocol: string;
}
export interface SlowResource {
    path: string;
    durationMs: number;
    transferSizeBytes: number;
    initiatorType: string;
}
export interface PerformanceMetricsResult {
    lcp: LcpMetric | null;
    cls: ClsMetric | null;
    inp: InpMetric | null;
    navTiming: NavTimingMetric | null;
    slowResources: SlowResource[];
    longTaskCount: number;
    captureSuccess: boolean;
}
export declare function injectPerformanceObservers(page: Page): Promise<void>;
export declare function collectPagePerformance(page: Page): Promise<PerformanceMetricsResult>;