An assistant is only useful if people finish what they started.
Experience design for AI services is the practice of making an assistant usable enough that people complete the task, measured by completion rate rather than by satisfaction with the technology. An assistant that is technically correct and practically abandoned has solved nothing. The failure is rarely the model. It is an interface that assumes the user already knows the vocabulary of the organisation, a journey that restarts when a document is missing, or an Arabic experience that was translated rather than designed.