While operating my 2026 GMC Yukon AT4 (VIN [XXX] ) on [XXX] Pelahatchie, Mississippi, the panoramic moonroof spontaneously shattered at highway speed. No impact, no debris strike, no external cause. The failure produced a violent report and showered tempered glass into the cabin, forcing an emergency stop on the shoulder during heavy commercial truck traffic — a serious secondary-collision risk caused directly by the failure. I spent hours roadside clearing glass and duct-taping the open roof aperture to make the vehicle minimally drivable. Nighttime wind forced an unplanned overnight stay in north Alabama before a multi-hundred-mile drive back to Washington, DC with the vehicle compromised. In DC, I was forced to park the visibly compromised vehicle in a high-foot-traffic area with work valuables that could not be removed, then drive 20 miles to the dealer in heavy rain the next morning — exposing cabin, electrical systems, child seating positions, and headliner to water intrusion. The shattered glass fell directly above the second-row positions where my [XXX] and [XXX] daughters ride daily. They were not present. Had they been, close-range tempered glass would have created serious risk of injury to face, eyes, and airway, plus driver-distraction crash risk at highway speed. The vehicle is approximately [XXX] weeks old. This is the second manufacturing safety defect in under one month — the first a second-row driver-side captain's chair latch defect, filed separately. Re