SvelteKit Paraglide-JS Reproduction Example

This is a reproduction example for the issue I'm facing with SvelteKit and Paraglide-JS.

Steps

1. Clone this repository
2. Run npm install
3. Run npm run build && npm run preview
4. Open the browser and navigate to http://localhost:4173/
5. Try to change the language and see what happens.

Expected behavior

The language should change and the text and URL should be updated.

Actual behavior

The language changes for a split of a second but then it reverts back to the previous language and doesn't change the URL.

It doesn't matter if you use the preferredLocale as a strategy or not, the behavior is the same. (Just the initial language is different)

Reason

The reason for all of this are the urlPatterns from the vite config. If you remove them, everything works as expected.

import { paraglideVitePlugin } from "@inlang/paraglide-js";

export default defineConfig({
  plugins: [
    // ...
    paraglideVitePlugin({
      // ...
      urlPatterns: [
        {
          pattern: "/:path(.*)?",
          localized: [
            ["en", "/:path(.*)?"],
            ["de", "/:path(.*)?"],
          ],
        },
      ],
    }),
  ],
  // ...
});

If you leave them there, the bug occurs. I've use two examples from the docs.

1. Locale Prefixing
2. Translated Pathnames