Jeroen's same-day corollary to the zoom-ladder condition: no zoom level displays the authored heightmaps directly — even the orbital/planetary map is derived output, sampled at canvas resolution (continuous field, not fixed rasters). Kills zoom over/undersampling by construction and makes the map viewport-adaptive. import_heightmaps survives as input storage only; AtlasViewer's texture display path retires when the derived planetary rung lands. T-1143 design pass extended with items (e)-(g).