TS error regarding inferred type of 'appRouter'

The inferred type of 'appRouter' cannot be named without a reference to '../../../../node_modules/zod/v4/core/util.d.cts'. This is likely not portable. A type annotation is necessary.ts(2742)

import type { inferRouterInputs, inferRouterOutputs } from "@trpc/server";
import { router } from "../alt";

export const appRouter = router({...})

import { TRPCError, initTRPC } from "@trpc/server";
import superjson from "superjson";
import type { Context } from "./context";

const t = initTRPC.context<Context>().create({
  transformer: superjson,
  errorFormatter({ shape }) {
    return shape;
  },
});

const isAuthed = t.middleware(({ next, ctx }) => {
  if (!ctx.auth?.userId) {
    throw new TRPCError({ code: "UNAUTHORIZED", message: "Not authenticated" });
  }
  return next({
    ctx: {
      ...ctx,
      auth: ctx.auth,
    },
  });
});

export const router = t.router;
export const publicProcedure = t.procedure;
export const protectedProcedure = t.procedure.use(isAuthed);