Analytics script or SDK is present and loaded

Without an analytics SDK wired up, you cannot answer basic product questions: which acquisition channels convert, which pages drive signups, which features get used. You are shipping to production blind. Marketing spend gets allocated on gut feel, pricing experiments cannot be measured, and conversion regressions go undetected until revenue drops. Installing a package without wiring a measurement ID is worse than not installing it — it signals the job is done when zero data is flowing.

Pick one analytics provider and wire it end-to-end. For Vercel-hosted Next.js, the fastest path is npm install @vercel/analytics plus <Analytics /> in app/layout.tsx. For product telemetry, use PostHog with posthog-js initialized in a 'use client' provider. Store the measurement key in NEXT_PUBLIC_GA_MEASUREMENT_ID or equivalent and reference it from the initialization site.