Client half — the cascade's district tier is now visible in the Atlas map.
- protocol.gd: decode the district_grid field from AtlasLayerResponse.
- atlas_viewer.gd: a gen_district ('MRPH') toggle in OVERLAY_DEFS + the
district-grid generation state (set/get) + wire it from the Ready response.
- atlas_marker_overlay.gd: _draw_gen_district() paints the coarse cols×rows grid,
each cell coloured by its MorphologyZone discriminant (D-239 §6, 17-zone
palette), semi-transparent under the Layer-1 line overlays. Planetary map view
(not the 2km on-demand districts — those are Phase 5 in-world).
gdUnit4 test: overlay registered + district grid round-trips through the viewer
and the protocol decode. Visual tuning of the palette can follow once eyeballed
in the running Atlas.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>