The merchant decides what customer task the feature should handle and which business rules apply. The agency helps decide which parts of the prototype can be carried into the shop reliably. Together they agree how to accept the feature and who supports it after launch.
What carries over from the prototype?
A merchant has built an assistant that finds spare parts by machine model. The demo shows that customers can get somewhere quickly with a model number. In production, the team keeps that flow and connects the maintained compatibility data. It gives unknown model numbers and ambiguous matches a clear next step. The agency and merchant agree which cases to retest regularly and who corrects the underlying data.
What needs to be in place at launch?
Check the feature with real variants and safely prepared test data. Give business changes an owner and technical incidents a point of contact. Rehearse a shop update and switching the feature off. In everyday use the merchant should be able to see whether the assistant makes suitable suggestions and safely remove it from the journey if something goes wrong.