Cache-Control headers optimized for hashed assets

Hashed assets are designed for aggressive caching — the filename changes only when the file content changes, so browsers can safely cache them forever. Without immutable, max-age=31536000, browsers re-validate these files on every visit, adding a round-trip for each asset even when the content is identical. Conversely, if HTML files are cached with a long max-age, users miss updates entirely until the cache expires. ISO 25010:2011 time-behaviour frames the latency; the business impact is repeat visitors waiting on unnecessary network round-trips.

Set Cache-Control: public, immutable, max-age=31536000 for hashed assets and no-cache for HTML in your deployment config.

// vercel.json
{
  "headers": [
    {
      "source": "/_next/static/(.*)",
      "headers": [{ "key": "Cache-Control", "value": "public, immutable, max-age=31536000" }]
    },
    {
      "source": "/(.*)\.html",
      "headers": [{ "key": "Cache-Control", "value": "public, no-cache" }]
    }
  ]
}