NextEdu/src/app/api/web-vitals/route.ts

import { NextResponse } from "next/server";

/**
 * Web Vitals 上报端点
 *
 * 接收前端 navigator.sendBeacon 上报的 LCP/CLS/INP/FCP/TTFP 指标,
 * 当前实现:写入服务端日志(便于开发期查看),生产可接入监控系统。
 *
 * 性能预算基线(见 docs/architecture/audit/performance-budget-audit-report.md):
 * - LCP ≤ 2.5s,INP ≤ 200ms,CLS ≤ 0.05,TTFB ≤ 800ms,FCP ≤ 1.8s
 * - 超出预算的 "poor" 级别会以 warn 级别日志记录便于排查
 */
export const runtime = "edge";

type WebVitalEntry = {
  name: string;
  startTime: number;
  duration: number;
  entryType: string;
};

type WebVitalsPayload = {
  id: string;
  name: string;
  value: number;
  rating: "good" | "needs-improvement" | "poor";
  delta: number;
  entries: WebVitalEntry[];
  path: string;
  timestamp: number;
};

// 性能预算基线,超出即标记为 poor
const BUDGETS: Record<string, number> = {
  LCP: 2500,
  INP: 200,
  CLS: 0.05,
  FCP: 1800,
  TTFB: 800,
};

export async function POST(request: Request): Promise<NextResponse> {
  let payload: WebVitalsPayload;
  try {
    payload = (await request.json()) as WebVitalsPayload;
  } catch {
    return NextResponse.json({ ok: false }, { status: 400 });
  }

  const budget = BUDGETS[payload.name];
  const isOverBudget = budget !== undefined && payload.value > budget;

  // good/info 级别用 info,rating poor 或超预算用 warn
  if (payload.rating === "poor" || isOverBudget) {
    console.warn("[web-vitals] over-budget", {
      name: payload.name,
      value: payload.value,
      rating: payload.rating,
      budget,
      path: payload.path,
      id: payload.id,
    });
  } else {
    console.info("[web-vitals] reported", {
      name: payload.name,
      value: payload.value,
      rating: payload.rating,
      path: payload.path,
    });
  }

  return NextResponse.json({ ok: true });
}