sure/app/models/enable_banking_item/provided.rb

module EnableBankingItem::Provided
  extend ActiveSupport::Concern

  def enable_banking_provider
    return nil unless credentials_configured?

    Provider::EnableBanking.new(
      application_id: application_id,
      client_certificate: client_certificate
    )
  end

  # Build PSU context headers for data endpoint calls.
  # The Enable Banking API spec mandates: "either all required PSU headers or none".
  # We can only provide Psu-Ip-Address (from last_psu_ip stored at request time).
  # If the ASPSP requires other PSU headers we cannot satisfy server-side, we send none
  # to avoid a PSU_HEADER_NOT_PROVIDED error for partially-supplied headers.
  def build_psu_headers
    return {} if aspsp_required_psu_headers.blank?

    required = aspsp_required_psu_headers.map(&:downcase)

    # Only attempt to satisfy the headers if the only required one is Psu-Ip-Address
    # (the one we can populate from stored data)
    satisfiable = required.all? { |h| h == "psu-ip-address" }
    return {} unless satisfiable && last_psu_ip.present?

    { "Psu-Ip-Address" => last_psu_ip }
  end
end