region_centre_latitude_deg mapped row 0 to the north pole with lat_frac
clamped [0,1] while the derive core floor-divides equator-anchored signed
world metres — every northern-hemisphere region clamped to +90 (polar
everywhere) and the southern hemisphere read as compressed northern
tropics. Now mirrors the derive core's exact inverse mapping (lat_frac =
centre_y/meridian clamped [-0.5,0.5], lat = -frac*180). The ticket's
in-the-wild datapoint flips as predicted: GJ338Bd region (136,43), old
baseline +13.94N/26.8C -> new -76.06S/10.3C; the 76S district cell now
derives Lake/2.07C/Light glaciation. Goldens regenerated (believability +
window derivation, stable on rerun); two region_profile unit tests
repositioned — their probe coordinates meant different places under the
old convention. step_canvas rung-0 already used the correct signed
convention; layer_proxy's pole-anchored pseudo-grid stays deferred to
T-1181's rung-0 rebuild per D-256(f).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
jpmschweitzerandClaude Fable 5
07f0fa307f