The unfurl has to be buttery — there are a million spinning globes

There are a million spinning globes on the internet. The only reason to build another one is if the transition from sphere to flat map feels like unrolling paper, not like a GPU having a bad day. First attempt at the unfold: interpolate D3's clipAngle from 90° to 180° while blending the orthographic and equirectangular projection math. Result: "striations, almost like threads attached to parts of the globe." D3 inserts vertices along the clip circle boundary, and the blended projection maps those clip-edge vertices to wildly wrong positions. The fix was to abandon clip interpolation entirely. Remove clipAngle during the transition, split countries into front and back hemispheres manually, fade the back hemisphere in with distance-based opacity, and delay the clipAngle(90) restoration until the projection is 99.8% orthographic. No more threads. No more artifacts. Just coastlines dissolving from sphere to rectangle over 2.2 seconds with cubic ease-in-out.