9  Grid geometry and weights

For rectilinear grids, cube_cell_area() returns horizontal area, cube_layer_thickness() derives vertical thickness, and cube_cell_volume() combines both. cube_polygon_weights() returns sparse intersections suitable for downstream aggregation.

CRS must be known and compatible. Curvilinear/unstructured grids and general antimeridian handling are outside the current core. Polygon weights remain experimental during the 0.x series.