clientContext empty when invoking identity-login

I just hit a similar/same issue.

Following the Docs here implies that I should be able to find a user object on the context.clientContext when a logged-in user accesses a Netlify Function.

However this:

exports.handler = async function (event, context) {
  const { identity, user } = context.clientContext;
  return {
    statusCode: 200,
    body: JSON.stringify({ message: `Hello ${ user }` })
  };
}

… returns

{ message: Hello undefined }

I have confirmed that the user is logged in and as @kristoferlund says there is user data available in the event payload.

Am I missing something about the way this works?