fetch

# File actionpack/lib/action_controller/metal/request_forgery_protection.rb, line 317
      def fetch(request)
        contents = request.cookie_jar.encrypted[@cookie_name]
        return nil if contents.nil?

        value = JSON.parse(contents)
        return nil unless value.dig("session_id", "public_id") == request.session.id_was&.public_id

        value["token"]
      rescue JSON::ParserError
        nil
      end