HeightCurve (pure static, D-035): calibrated monotonic piecewise map —
identity at/below sea 0.15; ease-out toe to the orange ceiling 0.206
(75% coverage, knot t1=P75=0.628736 from batch-04's pooled flat-sea
land CDF, 340.6M samples); linear rise to red 0.27 (t2=P90); smooth
shoulder to the 50m plateau shelf 0.3492 (t3=P93); near-flat plateau
step (t4=P96); accelerating spike to the 220m peak cap 1.0265; linear
tail past the calibrated max. Strict monotonicity asserted numerically
at startup, loud throw on violation.
Applied in GenerateTopography AFTER noise+falloff+Trench, BEFORE the
crater carve (carve cuts curved terrain; rim/bowl untouched by the
curve). Biome oracle mechanism: a retained uncurved classify heightmap
(alias of _heightMap when off, zero cost) feeds biome rules, both
flood fills, and the shared water predicates — classification is
curve-invariant by construction. Towns/roads/diagnostics/exported
heights use curved terrain; town positions may legitimately move.
Config gate TerrainCurve: "off"|"v1" (default v1), unknown values
rejected loudly.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
