start-core/middleware

TanStack Start middleware is coordinated using createMiddleware to enforce execution order: middleware → inputValidator → client → server. Context passes via next(), integrating with start.ts global configuration for predictable SSR and server function behavior.

The correct middleware execution order is middleware → inputValidator → client → server. Enforcing this sequence ensures predictable behavior and security across client and server boundaries for server functions and routes.

You pass context through TanStack Start middleware using the next() function. This allows data and configuration to propagate sequentially through the middleware stack before reaching server routes or server functions.

Yes, you can apply middleware globally by integrating it with the start.ts global configuration. This centralizes middleware configuration to apply consistently across both server routes and server functions.

Yes, TanStack Start middleware supports optional input validation. It is positioned in the execution sequence between the initial middleware and the client and server phases to validate inputs before processing.

Server functions may run before client middleware completes if the definitive execution order is not enforced. Using createMiddleware ensures the sequence runs middleware → inputValidator → client → server to prevent boundary issues.