Next.js App Router Caching: Why Your Data Stayed Stale

Next.js caching confusion usually comes from treating rendering and data freshness as the same thing — they're not. By adding server render timestamps and API response timestamps as independent debug markers, you can clearly see whether a route re-rendered vs. whether fresh data arrived. From there, choosing between force-cache, no-store, and revalidate becomes a measurable engineering tradeoff, not a mystery.