The operator (poisson_operator + merge_small_cells), Level::new's activity,
masked couplings, z links and cell/colour lists, the link CSR, the
components' count and singular count (lock-free union-find), and the f32
fine export with its parent map, built on the device from DeviceCut's
projection tables into the CG's and V-cycle's persistent buffers
(e3_pset.cu, poisson/device_cg/setup.rs). RTX_E3_BAND_CHECK=1 compares every
structure against the host build bit for bit. Fallback to the host setup
(logged once) with gradient weights or a periodic z of <= 2 planes.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
