Two caches, one invalidation (edited 16:14:52)

Varnish holds the API responses, Next.js holds the rendered routes.

Saving a node has to reach both. Varnish gets a BAN keyed on the tag; Next.js gets a webhook that maps the tag back to the routes that depend on it. Miss one and the site shows two different versions of the truth depending on which cache answered.

data fetched at	`2026-08-09T16:14:53.867Z`
content changed	`2026-08-09T16:14:52.000Z`
page rendered at	`2026-08-09T16:30:47.541Z`
Drupal cache tags	`node:2`
route tag	`drupal_250f1b896c851301`
Varnish	`X-Cache: MISS`
rendered by	`nextjs-856c764f7f-xs62t`

This page depends on node:2 and nothing else. Saving a different node must not change the “rendered at” stamp above.