debug block

Top-layer placeholder for generated architecture. The clearest example is temple-town's top story decoration, which fills most of its cap with this slot instead of committing to one hard-coded finished block in the serialized voxel data.

Wells, towers, work stations, and larger brick houses also place it on rooflines or pinnacle points. Read it as a worldgen capstone marker: meaningful inside prefab assembly, empty of purpose when spawned by itself.