PMP Practice: Optimize alignment between stakeholder needs, expectations, and project objectives

Birch Volkov is leading a mobile app development project for Swift Pulse Labs, a startup creating a peer-to-peer marketplace for local artisans. The executive sponsor, who comes from a traditional manufacturing background, insists on detailed upfront requirements and a comprehensive project plan with fixed milestones before any development begins. However, user research indicates the target market's needs are still evolving, and early beta testers have provided conflicting feedback about core features. The development team has strong agile experience and has expressed concern that a rigid plan will prevent them from incorporating market learning. The sponsor has allocated budget for the next six months but needs to see a working product within three months to secure additional Series A funding. Birch has already facilitated an initial product vision workshop with key stakeholders. Which approach should Birch take to address the sponsor's concerns while best serving the project's success?