Minimal Reproduction Case for Supabase SSR Auth Issue

This project demonstrates an issue with @supabase/ssr where supabase.auth.getUser() fails with AuthSessionMissingError in Next.js (v15.2.4 tested) API Routes, despite a valid authentication cookie being present.

Related GitHub Issue: [Link do Twojego zgłoszenia na GitHubie - wstawisz później]

Steps to Reproduce

1. Clone this repository.
2. Create a .env.local file based on .env.local.example with your Supabase project credentials.
3. Run npm install.
4. Run npm run dev.
5. Open the application in your browser (e.g., http://localhost:3000/login) and log in with a valid user. You should be redirected to /dashboard.
6. Open browser developer tools, find the sb-<YOUR_PROJECT_REF>-auth-token cookie, and copy its value (ensure it's cleaned, without base64- prefix or quotes).
7. Open a terminal and run the following curl command (replace <PORT> and <PASTE_CLEANED_COOKIE_VALUE_HERE>):

   curl -X GET \
     -H "Cookie: sb-<YOUR_PROJECT_REF>-auth-token=<PASTE_CLEANED_COOKIE_VALUE_HERE>" \
     -v \
     http://localhost:<PORT>/api/test-auth
   
     Observe the curl output (shows 401 Unauthorized) and the server logs (npm run dev terminal shows AuthSessionMissingError).