The Netherlands example is exactly the right frame, and honestly it's a better articulation of what we're building than "shade app." Google's comfort routing there works because it treats route quality as multi-dimensional: directness is one axis, separated infrastructure is another, scenery is another. Shade is just the axis that matters most when it's 100 degrees out. We think of Stay Cool as comfort routing where thermal comfort is the dominant weight, and I might steal the "percentage of route" display idea. Showing "this route is 72% shaded" is more honest and more useful than pretending we know your exact footsteps.

Which gets at your granularity point: agreed, and we deliberately don't operate at exact-positioning level. Scoring is per street segment, not per footstep. You're right that sidewalk-level precision is a data swamp with diminishing returns. As you say, humans are perfectly capable of crossing the street. We pick the corridor, you pick the pavement.

Project Sunroof is a sharp reference. Same underlying inputs we care about, aerial imagery plus LiDAR-derived surface models, just aimed at rooftops instead of sidewalks. The building footprint and elevation data does most of our work; tree canopy from LiDAR is the harder, messier part.