react-start/server-components

To implement React Server Components in TanStack Start, use primitives like createCompositeComponent and renderServerComponent to build server-rendered fragments while maintaining server-only boundaries. This approach ensures data stays on the server and exposes interactive slots for client controls.

Stale data in TanStack Start RSC typically occurs due to incorrect cache ownership or missing invalidation paths. You must explicitly invalidate the correct cache layer—Router, Query, or HTTP cache—responsible for the mutated route data to force a fresh server fetch.

Choose Router cache for route-shaped data tied to navigation, Query cache for reusable fragments, and HTTP cache for cross-request reuse. Selecting the correct cache owner prevents data ownership conflicts and ensures proper invalidation paths during mutations.

Yes, you can migrate from Next.js App Router to TanStack Start RSC. The process involves diagnosing migration gaps, remapping loader ownership, and selecting the correct SSR mode to satisfy current Flight-serializable slot contracts and server function requirements.

Fix SSR mode mismatches and serialization issues by ensuring your React 19 server components adhere to Flight-serializable slot contracts and validate server function inputs. Correctly configuring the SSR mode prevents hydration errors and client-server data structure inconsistencies.