Call tRPC procedures directly from server code using t.createCallerFactory() and router.createCaller(context) for integration testing, internal server logic, and custom API endpoints. Catch TRPCError and extract HTTP status with getHTTPStatusCodeFromError(). Error handling via onError option.
Break a tRPC backend into multiple services with custom routing links that split on the first path segment (op.path.split('.')) to route to different backend service URLs. Define a faux gateway router that merges service routers for the AppRouter type without running them in the same process. Share procedure and…
Set up real-time event streams with async generator subscriptions using .subscription(async function() { yield }). SSE via httpSubscriptionLink is recommended over WebSocket. Use tracked(id, data) from @trpc/server for reconnection recovery with lastEventId. WebSocket via wsLink and createWSClient from @trpc/client…
Configure input and output validation with .input() and .output() using Zod, Yup, Superstruct, ArkType, Valibot, Effect, or custom validator functions. Chain multiple .input() calls to merge object schemas. Standard Schema protocol support. Output validation returns INTERNALSERVERERROR on failure.
Migrate from @trpc/react-query (classic) to @trpc/tanstack-react-query. Run npx @trpc/upgrade CLI for automated codemod. Manually migrate remaining patterns: hook-based to options-factory, utils.invalidate to queryClient.invalidateQueries with queryFilter, provider changes.
Set up @trpc/tanstack-react-query with createTRPCContext(), TRPCProvider, useTRPC() hook, queryOptions/mutationOptions factories, query invalidation via queryClient.invalidateQueries with queryFilter, and type inference with inferInput/inferOutput.