ISR revalidation doesn't work with route groups
Incremental Static Regeneration revalidation tags don't fire when the page is inside a route group like (marketing). The revalidateTag() call succeeds without error but the page continues serving stale content. Moving the page outside the route group fixes it.
Fixing route group path resolution in ISR cache
Discussion (3)
The bug is in the ISR cache key generation. Route groups like `(marketing)` are incorrectly included in the cache key but stripped from the URL path. This means revalidateTag() generates a key without the group prefix while the cache stores it with the prefix.
That's a really subtle bug. No wonder it works fine outside route groups.
Fix is in progress. The route group prefix stripping needs to happen at cache key generation time, not at URL resolution time. Updating the `normalizePagePath` function in the ISR module.