Describe the problem

I'd like to enhance a remote function with additional but optional behavior.

In my remote function, I'm getting the user's session. By default, this function validates the session based on local JWT information from a cookie (i.e. no additional network request). However, there may be scenarios where I still want the session data but also need to verify the user of that session against a third-party backend server (they could have been banned, signed out globally from another device, etc, but their JWT is still valid).

import { getRequestEvent, query } from "$app/server"
import type { Session } from "@supabase/supabase-js"
import { getValidatedSession } from "./shared.js"
import * as v from "valibot"

export const getSession = query(
  v.optional(v.boolean()),
  async (validate_user): Promise<Session | null> => {
    const { locals } = getRequestEvent()

    return await getValidatedSession(locals.supabase, validate_user)
  }
)

The code works, but throws a type error whenever I'm not passing an argument.

Describe the proposed solution

This can be resolved if we make a change to the type (used AI here):

export type RemoteQueryFunction<Input, Output> = (
-  arg: Input
+  ...args: undefined extends Input ? [arg?: Input] : [arg: Input]
) => RemoteQuery<Output>;

Which yields no type error when passing in no arg,

but still, correctly, shows a type error if a passed-in arg doesn't match the schema

Rinse and repeat for any other remote function types this should apply to.

Importance

would make my life easier