start-server-functions

Topics in the source

• TanStack Start Server Functions
• Agent Workflow (MANDATORY)
• Critical Rules (read first)
• Overview
• Architecture
• Reference Guide
• Concepts
• Templates

Covers createServerFn, TanStack Start's same-origin type-safe RPC mechanism: GET/POST methods, .validator() (Zod or a plain function), .handler(), the useServerFn hook, FormData input, Response output, strict serialization, throwing redirect()/notFound(), server context utilities, and CSRF protection. Server functions run only on the server but are callable from loaders, components, hooks, and other server functions. Targets @tanstack/react-start v1.169.5. Critical rules: a server function is an independent HTTP endpoint reachable directly, so a route's beforeLoad redirect protects the UI only — auth must live inside the handler or its middleware for every function touching private data; never use Next.js/Remix patterns ("use server", getServerSideProps, Remix loader/action); loaders are isomorphic, so DB/secrets/filesystem access belongs in a server function, never a loader; useServerFn is mandatory when a function throws redirect() or notFound() (optional otherwise); and strict serialization is on by default (FormData allowed as POST input, Response as output). Includes templates for a full CRUD module and for FormData submissions with Zod validation. Do NOT use this skill for ra

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