Handle redirection in async calls

I have an app where on initial load the user is redirected to sign in page. Once the user is authenticated, he is then taken to homepage. While verifying the user, an HttpOnly cookie is also set to the browser. So now to remove the hassle for user to login every time he refreshes the app or opens it in another tab. I'm sending a authenticate request back to the server inside beforeModel hook of my application route. This will verify the user and page loads as expected. However if the server response has 401 (either because user logged out or cookie expired) the app will redirect him to login page. Everything works fine and as expected.

But there are few things tricky to resolve.

1. If the user gives path as /login I need to wait for the authenticate request to complete before deciding on to render the login template or to redirect to home screen if he is already logged in.

2. Also wait for validate call to complete before executing the model hook in target url. I saw the modal request going to server even when the response was 401 for authenticate call.

A good example is in github page, where once you log in and go to /login page they take you to your home page.