rst9454/Auth_WebApplication — reverse-engineered prompt

Build me a simple web application for user authentication. I want people to be able to create an account, log in with their email and password, stay logged in while they use the site, and log out when they are done. The app should check their credentials against stored user records and only let logged in users see a protected page.

Please make it feel like a real small app, with clean login and signup screens, clear error messages when details are wrong, and a basic home page that changes depending on whether the user is signed in. Keep the code easy to understand and include whatever setup is needed so I can run it locally.

Use sensible security defaults, like hashing passwords and not exposing sensitive information. If you need to choose the stack, pick something common and straightforward. Look up current docs online if you need to.