DeviceCg::new_device: level 0 by refresh_device, level 1's operator
coarsened on the device (Level::coarsen per coarse cell, children in
ascending index order) and brought down, levels 1.. by Hierarchy's loop
(Hierarchy::chain_below, export_levels), level 0's children lists on the
device. Falls back to DeviceCg::new when the hierarchy would stop at level 0.
RTX_E3_BAND_CHECK=1: every level against export_hierarchy, the fine
structures as refresh_device's check, the raw components' singular flag.
DeviceCg::new gains profile laps; DeviceVcycle::new split into upload_level +
from_levels, export_hierarchy into export_levels (same code).
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
