How to access refresh_token from Strava in auth-astro (auth.js)?

Question

I'm working on a user authentication in an Astro project (using SSR). I'm using auth-astro and followed this tutorial to do basic auth (it works): https://blog.otterlord.dev/posts/auth-astro/

However, I'd like to store user's refresh_token returned by Strava in the backend for nightly data pulls. I can't figure out how to access raw HTTP response from Strava, containing the access_token, refresh_token and athlete object. I managed to log what is supposed to be the token using this video: https://www.youtube.com/watch?v=fYObrr3jf0w , but it does not match Strava response schema:

Strava response schema:

{
  "token_type": "Bearer",
  "expires_at": 1568775134,
  "expires_in": 21600,
  "refresh_token": "e5n567567...",
  "access_token": "a4b945687g...",
  "athlete": {
    #{summary athlete representation}
  }
}

My auth.config.ts:

import Strava, { type StravaProfile } from '@auth/core/providers/strava'
import { defineConfig } from 'auth-astro'

export default defineConfig({

    providers: [
        Strava({
            clientId: import.meta.env.STRAVA_CLIENT_ID,
            clientSecret: import.meta.env.STRAVA_CLIENT_SECRET,
            authorization: {
                params: {
                  scope: `read,read_all,profile:read_all,activity:read,activity:read_all`
                }}
        }),
    ],
    callbacks: {
        async session({ session, token }) {
            console.log(token)
            session.user = token as any;
            return session;
        },
    }
})

My logs:

17:31:35 [200] / 8ms
17:32:10 [watch] auth.config.ts
{
  name: 'Tomasz Łyszczyk',
  picture: 'https://lh3.googleusercontent.com/a/ACg8ocKSNH-BqDQkG0J-NwPaUFpjqDUf9MOF-YiufEJEfJD7g_c=s96-c',
  sub: '64390882',
  iat: 1704557624,
  exp: 1707149624,
  jti: 'acda374b-ccd5-4ac1-8691-683d83c8475d'
}
logowanie w index
{
  user: {
    name: 'Tomasz Łyszczyk',
    picture: 'https://lh3.googleusercontent.com/a/ACg8ocKSNH-BqDQkG0J-NwPaUFpjqDUf9MOF-YiufEJEfJD7g_c=s96-c',
    sub: '64390882',
    iat: 1704557624,
    exp: 1707149624,
    jti: 'acda374b-ccd5-4ac1-8691-683d83c8475d'
  },
  expires: '2024-02-05T16:32:10.308Z'
}
17:32:10 [200] / 9ms

I tried to access refresh_token in response from Strava using auth-astro (auth.js), logging the token, but can't figure out where it is stored.