(1) The provisions of sections 677 to 686 do not apply if a person performs work or services in connection with the affairs of another person in the belief that they are their own affairs.
(2) If a person treats work or services in connection with the affairs of another person as their own despite knowing that they are not entitled to do so, then the principal may assert claims resulting from sections 677, 678, 681 and 682. If the principal so asserts them, then they are under a duty to the voluntary agent under section 684 sentence 1.