Performance regression alerts configured

A monitoring dashboard that collects LCP data but has no alert threshold for regression is a passive tool — it shows you that LCP increased from 1.8s to 3.2s only after someone manually checks the dashboard. ISO 25010:2011 time-behaviour requires measuring and acting on performance data; an alert on LCP regression > 200ms converts monitoring from a reporting artifact into an active safety net. Without alerts, performance regressions persist in production for days or weeks before anyone investigates.

Define alert thresholds in your monitoring service (Datadog, New Relic, Sentry, or Grafana) for each Core Web Vital. For code-defined thresholds, document them in a constants file and reference them in your alert configuration.

// lib/monitoring/thresholds.ts
export const PERFORMANCE_THRESHOLDS = {
  LCP_MS: 2500,      // alert if LCP regresses above this
  CLS: 0.1,          // alert if CLS exceeds this
  INP_MS: 200,       // alert if INP exceeds this
  LCP_DELTA_MS: 200, // alert if LCP worsens by more than this vs. 7-day baseline
}