Add $routes type alias

[vladshcherbin]

Describe the problem

I'd love to use route data directly in $lib/components instead of passing props to reduce type boilerplate. This is possible with page.data from $app/state, but it lacks proper types, requiring manual type assertions:

import { page } from '$app/state';
import type { PageData } from "../../routes/listings/$types";

const { carsCount } = $derived(page.data as PageData)

The main challenge is importing the correct PageData type, especially in deeply nested components and routes - path can quickly become cumbersome.

Describe the proposed solution

I'd love to have $routes alias which points directly to generated route types so I can use it in any part of the app:

import { page } from '$app/state';
import type { PageData } from "$routes/listings/$types";

const { carsCount } = $derived(page.data as PageData)

It's already working by providing alias in svelte.config.js:

export default {
  kit: {
    alias: {
      $routes: '.svelte-kit/types/src/routes'
    }
  }
}

Would be nice to have it right of the box 🥳

Alternatives considered

Some generic with route path param would also be fine

Importance

would make my life easier

Additional Information

No response

[elliott-with-the-longest-name-on-github]

I'd be down for this -- added the help wanted label. We'd need docs (same ones we have for existing aliases) and an implementation. I think this would be in github.com/sveltejs/cli, though.

[Zakrok09]

Greetings! Is this issue still under consideration or unresolved? I would love to give it a try and open my own PR if that is the case.

I see however that it could be perhaps already implemented. On the Svelte documentation about the aliases, an info note is written about the $lib alias itself:

The built-in $lib alias is controlled by config.kit.files.lib as it is used for packaging.

Going (hopefully) within the code for this interface, there is a TSDoc left about routes. Should a 'right-of-the-box' implementation also be controlled for what is written in the config?

Also if this alias is to be added, would the utility file for vite exports have to be edited to include the alias?

Also according to the CONTRIBUTING.md, one should write up the docs for this in this repo as well. Should documentation about a potential $route alias be written under the Reference section of the docs?

Thanks!