THE PAYOFF: rivers now carry water. Each carved main river becomes a chain of
stepped flat water-body reaches — a new reach every RiverStepDropM (2 m) of bed
descent, sitting RiverWaterDepthM (1.2 m) above its bed, strictly descending to
the outlet. Reaches are ordinary water bodies (WBID cells + WBTB type 2 'river',
fresh; WSRF derives from body levels as ever), so river water renders through
the C1 path with the task-15 presence rule at its banks, untouched. Existing
bodies are never overwritten — a river MEETS its lake or the sea. Measured on
1280587109: 298 reaches across 6 rivers, 184,620 wet px, levels stepping 278 m
down to 39.5 m; in-engine, one valley frame renders surfaces 46.2-114.5 m.
Beds widened (RiverWidthScale default 1.75). Lake-enders: the stem's pooling
terminal IS a local minimum, so the first extension attempt (blind steepest
descent) dead-ended in 0 steps — replaced with the lowground Dijkstra to the
nearest classify-water cell; the E-lagoon river now joins its lake (87 px).
Smoothing is applied ONLY to lowland routes: smoothing upland stems moved them
off their carved valley floors into the walls (max cut 14.6 -> 27.3 m measured;
split restores valley-floor fidelity). TYPE_RIVER added to the WBTB registry
(parser validation extended; doc updated in the docs commit).
Task-22 nits fixed: max-cut is now CUMULATIVE vs the pre-pass surface (the
honest number: p95 carve 7.0 m; 339 cells island-wide exceed 20 m — localized
outlet-gorge notches where stems cross deposit ridges, deepest 26 m); and
0_height/0_water are re-drawn and re-captured AFTER the river pass so the
exported snapshots show beds and water.
Guards: flood guard holds (water pixels unchanged around the carve; the water
stage touches no heights), BIOME oracle md5-identical to the task-22 baseline,
0_water changed (that IS the river water), island top 457.65 m exact, crater
core excluded.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
LOWGROUND is the gate verdict and the locked default ('short' stays available
behind the dial for the record). Every river polyline (upland stem + lowland
reach) is now decimated with RDP(4.0) and rounded with 4 Chaikin passes —
numerically mirroring MapGenerator.SmoothPath, since this pass is Godot-free —
before the bed profile is built, so the carved centreline carries none of the
8-connected Dijkstra 45° kinks (task-22 §4 caveat a). The monotone-descent and
sea-clamp constraints are applied to the smoothed course, unchanged.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Executes the frozen task-21b plan as real terrain — the first river pass to
modify the render map. NO WATER (part 2b waters the gated routing style).
RiverCarvePass (D-035 numeric): reruns DrainageAnalysis in-pipeline
(deterministic — same seed, same eroded surface, same plan), routes each routed
giant's lowland reach to the nearest ocean by deterministic Dijkstra under two
config-gated cost models — 'short' (distance + uphill penalty; heads direct) vs
'lowground' (cost ~ elevation above sea; follows the lowest ground and
meanders) — then carves every promoted course as a parabolic channel with a
smoothstep shoulder. Width/depth grow downstream with sqrt(drainage); bed
profile forced monotone non-increasing toward the outlet (water must flow) and
clamped to sea + RiverSeaMargin EVERYWHERE, with below-sea cells read-only and
the crater core excluded — the erosion flood-guard discipline, asserted per
generation by the water-pixel A/B (throws on any change).
Pipeline slot: AFTER GenerateTowns (towns read the render map for land/slope/
water checks — carving first would move towns and destabilise every A/B) and
BEFORE roads (a full run's A* should see the beds).
ISLA_SERVER_CONFIG env override added to ConfigManager: batch/A-B tooling loads
an alternate config file and the developer's live ServerConfig.json is never
written by tooling again (the task-19 restore near-miss class is retired).
Measured, seed 1280587109 (both variants): oracle md5-identical to baseline
(BIOM/WBID bitwise equal), 0 newly-below-sea cells, below-sea untouched, island
top 457.65 m exact, lowest carved cell exactly sea+margin (37.85 m), and
Rivers='off' is bitwise identical to the task-19 blueprint. All routed giants
reach the ocean in both styles. Wander (polyline/straight): SHORT 1.02-1.06 vs
LOWGROUND 1.24-1.38; SHORT carves 811k m3 (cuts through rises, max cumulative
cut 14.6 m), LOWGROUND 481k m3 (goes around, 14.3 m). Pass cost ~25 s (plan
21 s, routing 1.4-2.5 s, carve 0.3 s).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
