A CohortMembership object looks like:

// One person's place in one cohort.
{
  // the ID of the membership
  "id": 9001,
  // the cohort the membership belongs to
  "cohort_id": 4002,
  // the member
  "user_id": 17,
  // the root account of the cohort
  "root_account_id": 1,
  // the status of the membership
  "workflow_state": "active",
  // the SIS import that last touched the membership, if any
  "sis_batch_id": 12,
  // when the user was added
  "created_at": "2026-01-15T10:00:00Z",
  // when the membership was last updated
  "updated_at": "2026-01-15T10:00:00Z",
  // the member's latest request in this root account; null without the view
  // analytics permission
  "last_activity_at": "2026-01-20T08:30:00Z",
  // whether the member leads this cohort or one of its ancestors
  "is_leader": false,
  // the member's active institutional tags visible from the cohort's account, as
  // id and name; empty unless institutional tags are enabled and the caller can
  // view them
  "institutional_tags": [{"id":5,"name":"Honors"}],
  // reserved; always null for now
  "role": null,
  // the member's display fields: id, name, sortable_name, short_name, email (null
  // without read_email_addresses), sis_user_id (null without read_sis or
  // manage_sis), login_id (null without view_user_logins), time_zone (a Rails
  // time zone name), last_login (null without the view analytics permission),
  // account_status (active, suspended or deleted, from logins in this root
  // account), and avatar_url when avatars are enabled
  "user": {"id":17,"name":"Dana Okafor","sortable_name":"Okafor, Dana","short_name":"Dana","email":"dana@example.com","sis_user_id":"S17","login_id":"dana","time_zone":"Mountain Time (US \u0026 Canada)","last_login":null,"account_status":"active"}
}