This is what google AI has to say.

Selling a project under construction, or Construction in Progress (CIP), requires special accounting treatment. The project's costs are accumulated in the CIP account until the project is completed, at which point they are transferred to the appropriate fixed asset account. If the project is sold before completion, the sale price is recorded as income, and the CIP account is cleared out, with the costs recorded as cost of goods sold, according to QuickBooks.