Is it permissible to profit from purchasing and contracting operations related to finishing items if there is a store or contracting office owned by one party, in addition to the agreed-upon supervision percentage?

It is not permissible for an agent to purchase for himself or to contract with an office he owns, unless authorized by the principal. This is because agency entails bringing the most advantageous outcome for the principal, whereas selling to oneself brings the most advantageous outcome for the agent. However, it is permissible if the principal grants permission and specifies the price.