curl -X POST 'https://api.example.com/role-assignments/batch' \
  -H 'Authorization: Bearer YOUR_TOKEN' \
  -H 'Content-Type: application/json' \
  -d '[
    {"roleId": "role_editor", "membershipId": "membership_jane_eng"},
    {"roleId": "role_viewer", "membershipId": "membership_agent_eng"}
  ]'

[
  {
    "id": "role_assign_0190a1b2-c3d4-7e5f-8a9b-0c1d2e3f4a5b",
    "roleId": "role_editor",
    "membershipId": "membership_jane_eng"
  },
  {
    "id": "role_assign_0190a1b2-c3d4-7e5f-8a9b-0c1d2e3f4a5c",
    "roleId": "role_viewer",
    "membershipId": "membership_agent_eng"
  }
]