A two-app Next.js system providing shielded ISR caching for multi-tenant platforms on Vercel. The shield layer provides cache protection during Core app deployments, enabling cache warming and preventing slow first requests.

Run the setup script: pnpm setup

This installs dependency and injects the project bin dir into your PATH, which allows you to use validation helpers.

"Normal" ISR (Incremental Static Regeneration) in Next.js caches pages tied to a deployment. When you deploy a new version, the ISR cache is replaced and must be rebuilt, causing slow first requests for pages not generated during build.

Shielded ISR solves this by providing a protective cache layer that serves content while the Core app warms its cache (via active reading) after deployment. This enables:

• Deferred prerendering: Defer static page generation until after build, then pre-warm by requesting each page
• Deployment Protection: Shield cache serves content while Core app ISR cache rebuilds
• Performance: Fast responses during the critical post-deployment period

See the architecture and data flow docs for more information.

Validating deployment behavior is done through the validator package. You can run pnpm validate from the root of the monorepo to test whether certain requests are being routed to the correct pages.

See the validation doc for more details.