title: How can I hook into an authentication callback during the login process with Meteor?
body: <p>Using meteor, I'd like to be able to augment a <code>user</code> record after they've logged in (authenticated) with an external service to get their authorization claims.</p>
  
  <p><strong>Update</strong>
  I am using the <code>{{loginButtons}}</code> handlebars helper widget.</p>
  
  <p>Currently, I see an <code>Accounts.validateNewUser</code> and an <code>Accounts.onCreateUser</code> that can be hooked into during the creation of a new user. These would be helpful initially, but my need is recurrent.</p>
  
  <p>I understand that there is the <code>allow</code> function that hangs off the <code>Meteor.Collection</code> as a means of authorizing a user's access to the collection -- which is precisely where I would use the <code>claims</code> that I intend to augment the user with to determine authorization.</p>
  
  <p>Does anyone know of a hook during the login process that would allow me to do this?</p>