Conditional typing of locals on different routes

[einarpersson]

Consider an app that has three top level routes
/(public)/**
/user/**
/admin/**

Consider now that both user and admin has authentication, and that there are two distinct types of users. The user is added to locals as

declare global {
	namespace App {
		interface Locals {
			user?: User | Admin
		}
	}
}

or perhaps

declare global {
	namespace App {
		interface Locals {
			user?: User
			admin?: Admin
		}
	}
}

I am checking for user etc in hooks.server.ts (and I am also using +page.server.ts on each protected page).

I would like to have it so that when I am in /user/*** the locals.user has type User and has type Admin when in /admin/*** (or, have it as separate properties on locals as shown in the second example above).

Is this possible somehow? Right now there is a lot of code duplication for me with typeguards everywhere...

[einarpersson]

I could add a typeguard /admin/+layout.server.ts and /user/+layout.server.ts which would reduce duplication somewhat, but it still won't help for all these sveltekit action handlers and server endpoints.