tRPC 11 + Zod router with server-side caller: working versions (tested 2026-10-15)

{
  "name": "trpc-zod-router",
  "private": true,
  "type": "module",
  "scripts": {
    "test": "node --import tsx --test test/*.test.ts"
  },
  "dependencies": {
    "@trpc/server": "11.19.0",
    "zod": "4.6.7"
  },
  "devDependencies": {
    "tsx": "4.23.15",
    "@types/node": "24.19.2"
  }
}

import { initTRPC, TRPCError } from "@trpc/server";
import { z } from "zod";

type Context = { userId: string | null };
const t = initTRPC.context<Context>().create();

const authed = t.procedure.use(({ ctx, next }) => {
  if (!ctx.userId) throw new TRPCError({ code: "UNAUTHORIZED" });
  return next({ ctx: { userId: ctx.userId } });
});

const notes: { id: number; owner: string; text: string }[] = [];

export const appRouter = t.router({
  hello: t.procedure.input(z.object({ name: z.string() })).query(({ input }) => `hello ${input.name}`),
  addNote: authed.input(z.object({ text: z.string().min(1) })).mutation(({ ctx, input }) => {
    const note = { id: notes.length + 1, owner: ctx.userId, text: input.text };
    notes.push(note);
    return note;
  }),
});
export type AppRouter = typeof appRouter;
export const createCaller = t.createCallerFactory(appRouter);

import { test } from "node:test";
import assert from "node:assert/strict";
import { createCaller } from "../src/router.ts";

test("public query", async () => {
  assert.equal(await createCaller({ userId: null }).hello({ name: "dev" }), "hello dev");
});
test("authed mutation", async () => {
  const note = await createCaller({ userId: "u1" }).addNote({ text: "hi" });
  assert.equal(note.owner, "u1");
});
test("unauthorized and invalid input", async () => {
  await assert.rejects(createCaller({ userId: null }).addNote({ text: "x" }), /UNAUTHORIZED/);
  await assert.rejects(createCaller({ userId: "u1" }).addNote({ text: "" }));
});