DayNight.SunShadow returns a cell offset opposite the sun's east-west position, longest near sunrise/sunset (low sun) and zero at noon/night, tilted slightly south so shadows fall in front of occluders. LightmapBuilder gains a directional shadow pass (MaxShadowCells length cap, SunShadowStrength darkening); LightmapSystem feeds it the current sun shadow each rebuild. Tests cover SunShadow's day-arc behaviour and the builder's directional darkening.