title: Why does Google OAuth2 re-ask user for permission when i send them to auth url again
body: <p>With the old google openid, when i sent a user (who had previously opted-in to my app) to the auth url, it would immediately redirect them back to my app.</p>
  
  <p>Now, with OAuth2, the auth url keeps asking the user for permission. I read some of the docs on this, but what I dont get is how this flow i supposed to work:</p>
  
  <ol>
  <li>User logs into google via my app and clicks ALLOW for permissions</li>
  <li>Days later, cookies are cleared, user comes back to my site, clicks "Login to google"</li>
  <li>User is not asked for permission again and they are immediately logged in.</li>
  </ol>
  
  <p>I think it has something to do with storing the auth token or refresh token in step 1,
  but in Step 3, I don't know who they are, so how can i match them with the proper auth or refresh token to gain a valid access token.</p>
  
  <p>In my tests, when I send them to the original auth url in step 1, they are asked for permissions again.</p>
  
  <p><strong>EDIT: Found the solution</strong></p>
  
  <p>The google-api puts "approval_prompt=force" by default when creating the auth url.</p>