nextjs app router `fetchRequestHandler`'s createContext doesn't run.

// /src/app/api/trpc/[trpc]/route.ts
import { fetchRequestHandler } from '@trpc/server/adapters/fetch';
import { appRouter } from '~/trpc/root';
import { ENV } from '~/env';
import { createTRPCContext } from '~/trpc/trpc';

const handler = (req: Request) =>
  fetchRequestHandler({
    req,
    router: appRouter,
    endpoint: '/api/trpc',
    onError: ({ path, error }) => {
      if (ENV.NODE_ENV !== 'development') return;
      console.error(
        `❌ tRPC failed on ${path ?? '<no-path>'}: ${error.message} `
      );
    },
    createContext: createTRPCContext,
  });

export { handler as GET, handler as POST };

// /src/app/api/trpc/[trpc]/route.ts
import { fetchRequestHandler } from '@trpc/server/adapters/fetch';
import { appRouter } from '~/trpc/root';
import { ENV } from '~/env';
import { createTRPCContext } from '~/trpc/trpc';

const handler = (req: Request) =>
  fetchRequestHandler({
    req,
    router: appRouter,
    endpoint: '/api/trpc',
    onError: ({ path, error }) => {
      if (ENV.NODE_ENV !== 'development') return;
      console.error(
        `❌ tRPC failed on ${path ?? '<no-path>'}: ${error.message} `
      );
    },
    createContext: createTRPCContext,
  });

export { handler as GET, handler as POST };

// /src/trpc/trpc.ts
import { initTRPC, TRPCError } from '@trpc/server';
import superjson from 'superjson';
import { ZodError } from 'zod';
import { getServerAuthSession } from '~/auth/auth';

export const createTRPCContext = async () => {
  console.log('Context');
  return await getServerAuthSession();
};

const t = initTRPC.context<typeof createTRPCContext>().create({
  transformer: superjson,
  errorFormatter({ shape, error }) {
    return {
      ...shape,
      data: {
        ...shape.data,
        zodError:
          error.cause instanceof ZodError ? error.cause.flatten() : null,
      },
    };
  },
});

export const createTRPCRouter = t.router;

const enforceUserIsAuthed = t.middleware(({ ctx, next }) => {
  console.log(ctx);
  if (!ctx.session?.user) {
    throw new TRPCError({ code: 'UNAUTHORIZED' });
  }
  return next({
    ctx: {
      session: { ...ctx.session, user: ctx.session.user },
    },
  });
});

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

// /src/trpc/trpc.ts
import { initTRPC, TRPCError } from '@trpc/server';
import superjson from 'superjson';
import { ZodError } from 'zod';
import { getServerAuthSession } from '~/auth/auth';

export const createTRPCContext = async () => {
  console.log('Context');
  return await getServerAuthSession();
};

const t = initTRPC.context<typeof createTRPCContext>().create({
  transformer: superjson,
  errorFormatter({ shape, error }) {
    return {
      ...shape,
      data: {
        ...shape.data,
        zodError:
          error.cause instanceof ZodError ? error.cause.flatten() : null,
      },
    };
  },
});

export const createTRPCRouter = t.router;

const enforceUserIsAuthed = t.middleware(({ ctx, next }) => {
  console.log(ctx);
  if (!ctx.session?.user) {
    throw new TRPCError({ code: 'UNAUTHORIZED' });
  }
  return next({
    ctx: {
      session: { ...ctx.session, user: ctx.session.user },
    },
  });
});

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