Up in the Cascade Mountains, 90 miles east of Seattle, a group of high-ranking Amazon engineers gather for a private off-site. They hail from the company’s North America Stores division, and they’re here at this Hyatt resort on a crisp September morning to brainstorm new ways to power Amazon’s retail experiences. Passing the hotel lobby’s IMAX-like mountain views, they filter into windowless meeting rooms.Down the hall, the off-site’s keynote speaker—Byron Cook, vice president and distinguished ...