A rung used to fix the gridunit SPACING, with the canvas extent falling out
of spacing x cell count. That is why the top of the ladder was unusable: at
REGION_M spacing a viewport-sized canvas spanned ~251,658 km — six times
around a rocky body — so the Region rung capped to the body and redrew the
Global picture pixel-for-pixel. "Global and region look the same" was not a
rendering bug; it was this relation, stated in metres.
Inverted: a rung fixes the EXTENT and the spacing falls out of the canvas
size. The shorter viewport axis spans exactly one cell of the rung's level,
so a widescreen window shows more ground on the long axis rather than less
on the short one. Every rung now shows the ground its name promises —
Region 262x466 km, District 4.1x7.3 km — and the canvas cell count is
viewport-driven and identical at every rung, so derive cost no longer varies
with depth and resize is free.
Consequences that fell out of the inversion rather than being chosen:
- Region leaves the orbital derive set. It was envelope-only because at
251,658 km nothing finer made sense; at 262 km it is a genuine provincial
map and takes the full courses-aware derive. Region having no rivers at
all was much of why the top of the ladder read flat. It also joins the
deep display ratio for the same reason.
- The S2 station-spacing floor is deleted, not retuned. It guarded an
O(1/spacing) blowup that the inversion makes structurally impossible (the
canvas cell count is now constant across rungs, so stations-per-course is
bounded however deep you scroll). Kept, it would do active harm in the
opposite direction: a 2,048 m pitch across a 3.6 km District canvas places
two stations and draws every river as a straight line. Station placement
gets its own generator pass.
- cap_extent_to_body is superseded and now a documented no-op. A canvas can
no longer over-request a body by construction. The residual question —
whether a rung's cell exceeds the whole body — is liveness, not capping,
and is_rung_live_on_body() answers it by omitting the rung. Empirically it
never fires on inhabited content: all six rungs are live on all 271
populated bodies with a radius.
- snap_to_gridunit no longer truncates its multiplier to int. Post-inversion
the deep rungs run sub-metre (Chunk ~0.12 m at a 1080 px short axis), where
int(spacing) floors to zero and would collapse every request centre onto
the origin.
Both sides derive spacing from the same three inputs (rung, echoed cell
extent, body radius) rather than one telling the other, so there is nothing
to keep in sync beyond the constant table itself. Body radius already
reaches the viewer via enter(); no wire change.
Pair session with Jeroen, 2026-07-26. D-243/D-255 amendments to be backfiled.
Co-Authored-By: Claude <noreply@anthropic.com>
Five findings from the araminta+hoshe round. Tapering now fires only on
a TRUE upstream source: the course's first raw world point is tested
against the canvas's own world bounds (conservative 1m epsilon) —
exact detection because the server crop keeps one point beyond the
window (layer_proxy crop_course_to_window lo = first_in-1, contract
documented), so crop passthroughs draw the old flat full-width cut and
never a false headwater. The averaged-normal joint is replaced by a
real mitre (half_w/cos(theta/2) recovered trig-free via the bisector
normal), clamped by a 2x mitre limit AND 0.45x the shorter adjacent
segment — restoring true perpendicular width at bends (the 29% pinch at
confluences is gone) and preventing the hairpin bowtie; the winding doc
now states the actual bounded guarantee. Antialiasing restored via the
hybrid: only the varying-width taper head draws as a ribbon; the
constant-width ~85% of every course keeps the original antialiased
draw_polyline (byte-identical for untapered courses), split at an
interpolated arc-length point sharing position and width — junction
capture evidence in .cache/screenshots/t1175-fix-round/. Flat-fill
single-element color array. Suite 24 -> 48 tests.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The single large polish pass Jeroen requested off the T-1170 captures,
benchmarked against RimWorld's world-map fluency. Courses now draw as
source-tapered ribbons: per-vertex width ramps from a hairline at the
upstream source to full class width over 15% of the course's arc length
(arc-length parameterized, not vertex-indexed, so point density doesn't
change the read), built as one draw_polygon ribbon with mitred joins.
Class width table retuned 0.9/1.4/2.2 -> 0.6/1.2/2.4: a clean ~2x
per-class ladder so a tributary-joins-trunk confluence reads as a join,
trunk held at its visually-proven weight, stream thinner per the
benchmark's thin/consistent/restrained grammar. Opacity untouched
(Araminta's T-1170 ruling stands). Coast-gradient item resolved as
already-correct (the coastal transition zones + elevation lightness
render the shoreline band; capture-verified) — no wire change. Stipple
assessment filed as T-1194. Eight new taper-geometry tests.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The two-layer client rebuild per D-255(a)(b)(e), replacing the
_canvas.scale continuous-zoom model with one viewer, one path, all six
rungs:
- step_canvas_protocol.gd: StepCanvasRequest/Response codec against
the T-1181 wire contract — incl. the discovered png_bytes subtlety
(rmp_serde without serde_bytes emits a msgpack int-array, not bin;
decode repacks via PackedByteArray before load_png_from_buffer) and
the extent-echo rule (read the server-clamped extent, never assume
the requested one).
- step_canvas/ component: transport (six-rung ladder, cursor-anchored
scroll steps, edge-scroll/WASD pan with re-request on edge crossing,
hard reset-to-Global), RTT terrain layer (Image.set_pixel colorize
per the c1 measured ruling, texture.update reuse on step-cross,
NEAREST coarse / LINEAR fine per rung), unscaled screen-space
annotation sibling (courses + settlement markers at literal px),
in-memory LRU cache (Tier 1; T-1183 layers the disk tiers beneath),
request lifecycle (pending retry, staleness gate, extent echo).
- Full _canvas.scale retirement in the same change: the zoom-scaled
canvas model, the _zs compensation family, select_rung /
MAX_COVERAGE_M / compute_tile_grid, the orbital-mosaic-vs-window
two-path split, _view_zoom/_canonical_fit_zoom — 10 source files
deleted; their 14 test suites deleted with them (T-1157 dead-goldens
rule; replacement visual-capture coverage is re-scoped T-1157).
- Surviving surfaces kept per the ticket: atlas_window_cache.gd's LRU
shape (the ticket's named file atlas_window_tile_set.gd was the
retiring orchestrator; the real LRU shape lives in
atlas_window_cache.gd — cited in step_canvas_cache.gd), overlay
colors, legend/overlay-bar chrome, AtlasViewer descend geometry.
Determinism boundary per D-255(e): the client interpolates only within
the closed server-supplied input set. 7 new gdUnit suites (164 cases)
incl. a real extent-echo bug caught by its own test during
implementation. Full client suite green (exit 0) with the live-gated
suites running against a worktree server build.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
jpmschweitzerandClaude