Le vicende del rapporto di appalto, in Giur. comm. 2025, fasc. 1. Rassegna di giurisprudenza.

The contract for the execution of works or services has in common with continuous execution contracts the need for execution to develop over a certain period of time. However, the client's interest is satisfied only in the final moment of delivery of the work. In fact, this contract is an intermediate figure between instant execution contracts and duration contracts: hence the name "prolonged execution contract", according to an effective definition of the doctrine, accepted by jurisprudence. This nature justifies its most characteristic elements, starting with the special regulation of unforeseen or unforeseeable circumstances that modify the agreed economic balance (art. 1664 of the Civil Code). Again, it is the nature of a long-term contract that explains the ius variandi, also of the project (articles 1659-1661 of the Civil Code), and which justifies how, even if the contract is not a aleatory contract, the normal risk has value more pronounced than in the other contracts.