oRPC

Wiring

import { RPCHandler } from "@orpc/server/fetch";
import {
  versionlessContext,
  versionlessClientInterceptor,
  versionlessAdapterInterceptor,
} from "@versionless/adapter-orpc";
import { v } from "./versionless";

const handler = new RPCHandler(router, {
  adapterInterceptors: [versionlessAdapterInterceptor(v)],  // sunset headers
  clientInterceptors: [versionlessClientInterceptor()],     // up/down per procedure
});

// wherever you handle the request:
const { matched, response } = await handler.handle(request, {
  prefix: "/rpc",
  context: { ...versionlessContext(v, { request }) },
});

This is exactly how the repo's demo app (apps/demo) wires its oRPC surface. Changes are keyed by procedure, exactly like the tRPC adapter:

v.change("2026-03-01", {
  describe: "user.create: name -> firstName/lastName",
  procedures: ["user.create"],
  request: { up: ... },
  response: { down: ... },
});

How it works

• Context stash. One HTTP request may batch several procedure calls, and the exchange is procedure-keyed — so versionlessContext stashes the instance + header getter on the context, and the client interceptor opens the per-procedure exchange itself, where path is known. Pass v to versionlessClientInterceptor(v) to override the stashed instance.
• clientInterceptors, not middleware. oRPC middleware cannot replace the input a handler receives. Client interceptors run after input decoding and before output encoding — exactly where up and down belong, and before .input() validation, so old-shape inputs pass current-shape schemas.
• Errors. A thrown ORPCError is rebuilt through error.down chains (its { code, status, message, data } shape is what your transforms see). A version past its sunset cutoff throws GONE (410) with the structured body as data; an invalid pin throws BAD_REQUEST.
• adapterInterceptors for sunset headers. Root interceptors run below oRPC's error-to-response conversion, so thrown errors would bypass them — the adapter-level interceptor sees the final web Response on every path and stamps Sunset / Deprecation onto it.

Telemetry

One event per procedure call, with route: "trpc:user.create"-style keys (procedure-keyed routes share the trpc: namespace) and adapter: "orpc". Under VERCEL the flush fires per call so events survive the function freezing.