| name | tanstack-start-server-functions |
| description | Implement, secure, review, or debug TanStack Start server functions. Use for createServerFn handlers, input validation, request context, redirects, not-found results, raw responses, progressive enhancement, streaming, static functions, cancellation, serialization, or server-only data access. |
TanStack Start Server Functions
Confirm the boundary
Read ../../docs/server-functions.md and ../../docs/execution-boundaries.md. Use a server function for application RPC. Use a server route when an external caller needs an ordinary HTTP contract.
Build the request pipeline
- Define one explicit serializable input object.
- Validate it before domain work.
- Resolve request context and session per request.
- Authenticate and authorize access to the concrete resource or tenant.
- Call server-only domain or data modules.
- Return an explicit serializable result, framework redirect/not-found value, or intentional raw
Response.
Preserve Start's same-origin protection. Never move secrets or trusted authorization decisions into client-callable code.
Keep code focused
Keep handlers thin and put reusable domain logic in server-only modules. Use middleware only for repeated cross-cutting context. Do not add generic error swallowing, hidden defaults, or a fallback value that masks a failed dependency.
Verify
Test malformed input, anonymous access, unauthorized resource access, success, domain failure, redirect, and not-found behavior. Inspect client output when a server-only import or secret could leak. Run a production build to exercise function ID generation and import protection.
Report the endpoint contract, security checks, serialization choices, and tests run.
