chat2/02 dissolved the terraces and lost two thirds of the mountain with them, then
concluded the loss was structural and needed a Phase-1 noise change. That conclusion
was wrong, and this commit is the refutation.
A monotone curve is a free reparametrization: it may be gentle in one place and steep
in another, and can lift bottom-heavy input into a substantial massif without ever
going flat. The area above a height is set by where the percentile->height mapping
crosses it, and that mapping is entirely ours to choose. The 02 sweep that "proved"
the loss structural varied climbFeather, which shapes the JOIN, not the mass
distribution — the wrong knob, and too strong a conclusion drawn from it.
Core/ClimbCalibration — the climb's control points are now MEASURED off the staircase
instead of invented from shape knobs. For p in {10,30,50,70,85,95} of above-ceiling
land, take that percentile's raw height and its staircase output height; PCHIP through
the pairs. That reproduces the staircase's elevation envelope, so the mountain mass
returns, while MinNormalizedSecant floors every grade so the flat bench and plateau
interiors become slope. The floor bites on exactly one segment — the plateau — which
is precisely where the staircase was flat.
ContinuousCurve.BuildCalibrated joins it to the same pinned lowland handover, the same
C1 join and the same per-seed spikeMax. The 02 analytic path survives unchanged as the
"before" contrast, and deliberately keeps its strictly-increasing-secant rule: a
calibrated curve is WAVY by design, so convexity is the wrong invariant for it and the
secant floor is the right one.
peakSharpness replaces summitDrama and fixes its bad trade. Drama steepened the peak by
pulling the summit ONSET down, dragging the whole massif with it (p99 199 -> 121 m).
Sharpness reshapes only above the last measured percentile, leaving that height fixed,
so peak and massif are independent: raising it leaves p90, >100 m and >220 m untouched
and only moves land within the summit.
Measured, both seeds, 2048:
variant >100 m >220 m p90
staircase (target) 16.05% 4.53% 127.4 m
continuous_02default 4.80% 0.63% 58.4 m
continuous_restored 14.25% 3.45% 123.2 m
continuous_bigger 19.70% 5.80% 163.5 m
Oracle all hard checks pass, including (a2) staircase still bit-identical to task 01's
dump and (d) lowlands bit-identical across every calibrated variant. New (g) reports
land above 100/220 m per variant and is deliberately NOT gated — it is a taste target
the developer tunes, and gating it would make mountainLift unusable. What it must never
do is stay silent, which is how 02 lost the mountain unnoticed.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DCWNaDZPfTiAy3meGNGgqt
rev 3 of the curve redesign. The developer's verdict on the 01 baseline was that the
LOWLANDS ARE GOOD; the fault is the terracing above them. So this adds a second curve
mode that preserves the low plain bit-for-bit and replaces everything above the flood
line with one smooth monotone climb.
Core/ContinuousCurve — piecewise, and the pieces have different loyalties:
- at/below sea: identity, as ever.
- above sea to K2: DELEGATES to HeightCurve's own toe+red branches. Not "equivalent" —
the same code path, so the same floats. Oracle (d) holds it to that.
- above the ceiling: a Fritsch-Carlson (PCHIP) monotone spline to the 420 m cap,
C1-joined to the red band's exit slope. Monotone by construction for any ordered
control points, which retires the 24-corner sweep; a 10k strict-increase sample runs
per seed anyway, because "cannot fail" is worth a millisecond.
- Build() REFUSES rather than degrades: a ceiling near the old bench, a drama that folds
the summit under its own onset, control-point secants that are not strictly increasing
(the no-magnet rule, enforced rather than hoped for).
Only BENCH_*/PLATEAU_* are dropped. SEA/ORANGE_CEIL/RED_CEIL survive because they are
the storm-ladder FLOOD TIERS and they live inside the preserved lowland; PEAK_CAP and
the per-seed spikeMax normalization survive as the summit.
Shelf detail is forced off in continuous mode: the flat benches it de-slabbed no longer
exist, and painting noise on the climb now would pre-judge what erosion should carve.
Oracle, all hard checks passing:
- (a1) curve off is bit-identical to Phase 1's dump.
- (a2) staircase mode is bit-identical to TASK 01's dump — the control is provably the
control, not a re-derivation. (CurveBaselineTool is pinned to Staircase so the config
default moving to Continuous cannot drift it.)
- (d) lowlands bit-identical to the staircase over 3.6M cells, every continuous variant,
both seeds. The lifted_WRONG bookend fails it on 1.6M cells, as intended.
- (f) sea identity per CELL, not per count, including 67M cells at 8192.
The finding, measured and recorded in the batch scratch: the massif SHRANK. Land above
100 m goes 14.9% -> 4.8%, above 220 m 4.5% -> 0.6%. A feather sweep to the practical
floor recovers ~1.3 points, so this is structural, not a tuning miss: the staircase's
highland area was an artifact of the bench and plateau acting as magnets, and a curve
with no magnets preserves the raw distribution's bottom-heavy shape. "No terraces" and
"the same land up high" are not both available from curve work alone.
Exploration batch, not convergence. A tuning pass follows once a direction is picked.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DCWNaDZPfTiAy3meGNGgqt
