Closes the C1-polish carryover. The cause was confirmed by a read-only dump
BEFORE any code was written, per the filed note's discipline; the chat had
guessed twice from screenshots.
DIAGNOSIS. WBID is classified from the UNCURVED heightmap — the classify
path that keeps the biome/water oracle byte-identical through all of
Phase B — while the mesh renders the CURVED one. Outside the crater those
two agree EXACTLY, and provably so: the curve is identity at sea and
monotonic, so Apply(raw) < sea iff raw < sea. Inside the crater they do
not. The carve lerps two different bases toward one target --
classify from raw, rendered from Apply(raw) -- and Apply(raw) < raw
throughout the lowland band (the toe compresses raw 0.15..0.516 into
0.15..0.206). So the rendered surface sinks FASTER than the classify
surface, leaving an annulus that renders below the waterline while WBID
still calls it dry.
MEASURED, seed 1825907253, map-wide:
wet columns 32,799,866
WATER-OVER-DRY (wet, mesh above Y) 1,101 scattered, not the story
DRY-UNDER-WATER (dry, mesh below sea) 375,824 <- the seam
...of which inside the crater carve: 100 %
Dump across the gradient at z=905: at x=3800 the classify surface sits at
47.55 m while the mesh renders 22.38 m -- 25 m apart, no water drawn. The
ring is west of the Capitol, which is exactly the developer's "flush on
the right, lifted toward the left".
Neither of the task's two candidate causes, and worth saying so: the water
LEVEL is flat and correct at 37.65 everywhere it is drawn (rules out B),
and the per-cell flat sheet is a rounding error next to this (1,101 px vs
375,824). It is the filed note's classify-vs-render mismatch, with the
crater carve as the mechanism.
THE FIX. Presence now takes two clauses: the blueprint's classification,
OR the rendered ground actually being under the ocean's surface. The
second clause tests exactly what the mesh draws (exactSurfaceY) against the
OCEAN BODY'S OWN level from WBTB -- the runtime still derives nothing, it
only notices that the ground it is drawing is under a surface the
blueprint gave it. By the identity above that clause can only ever fire
inside the carve, which is precisely the flooded bay it exists for.
MEASURED after, same seed: 241,415 -> 358,576 water columns, 454 -> 648
chunks, 117,161 seam columns recovered in the loaded region. Each run now
reports its own seam count.
2D PIPELINE UNTOUCHED, verified rather than asserted: the only changed
file is the runtime chunk manager, and a regeneration is byte-identical to
task 13's in every section but PRMS (timestamp + git hash). All four
snapshot PNGs md5-identical.
Static flat sheet, no animation, no water DATA change.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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