B1 (Ruling 5c): nature block split out of atlas_window_geometry.gd
(954/1000 cap pressure) into atlas_window_geometry_nature.gd; RIVER_
CLASS_VISIBLE_BY_RUNG replaced by SKELETON_CLASS_VISIBLE_BY_RUNG
(Region-only now) + COURSE_CLASS_VISIBLE_BY_RUNG (District trunk+
tributary; Quarter all three — the pre-announced Quarter-rivers-
return) with width/opacity companion tables as Araminta's single
revisit point; deliberately opposite unknown-tag fallbacks per reader
(skeleton->full, course->empty), documented.
B2 (Ruling 5a): Region dot-scatter upgraded to connected chords via
river_downstream — D8 direction decode (0-7 into drainage.rs's
(row,col) delta table, antimeridian wrap-aware), sentinel chain ends
(MOUTH=8 ring-on-land, EDGE_DRAIN=9 no ring, TERMINAL=10 reserved,
decodes like EDGE_DRAIN so the future endorheic server needs no
client change). Pure build_skeleton_chords() split from drawing for
render-free testability. Chord clip rule (3g pick): segment clips if
either endpoint OR midpoint is drawn water — three-point catches both
narrow-inlet and long-chord failure modes at one extra lookup;
documented. Self-caught during build: first draft misdecoded the
pointer as a river_cells INDEX; rewired to direction decode against
A1's real convention before leaving the branch. Dual revert-verified
(direction sabotage -> 6 named failures incl. the chain-threading
pin; midpoint-drop -> exactly the 1 named clip test). Suites:
geometry-nature 86/86, geometry 130/130, nature-overlay 24/24; full
sweep 3892 with only the 6 known pre-existing garment/gait failures
untouched by this batch; gdlint clean.
Tickets: T-1170
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
jpmschweitzerandClaude Fable 5
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