start-core/middleware

You can create type-safe middleware in TanStack Start using createMiddleware, which enforces proper method order and safe context handling. Attach the middleware to individual handlers or entire routes to apply processing logic like authentication or logging.

Request middleware runs on all server requests including SSR and routes, while server function middleware runs on both client and server phases. Server function middleware enables pre and post processing alongside context injection for client-server interactions.

You pass context through a middleware chain by calling next with a context object: next({ context }). This propagates data through the middleware chain directly to your downstream handlers in a type-safe manner.

Yes, you can configure global middleware in the src/start.ts file. This establishes universal behavior across the entire application, ensuring consistent processing like logging or validation for all server requests and functions.

You enforce authentication or feature flags by attaching middleware to your server functions. The middleware processes the request, validates policies, and injects context before the main server function logic executes.

Yes, TanStack Start server function middleware explicitly supports both client and server phases. This allows you to run pre-processing logic on the client and continue context passing or post-processing on the server.