# Lane A — progress log

## 2026-07-16 · Round 2 — crest law, TBN walls, the colorspace re-eyeball, stomach shape read

Two halves: the original session (cut off pre-NOTES; work rescued by F as `f0982e7` — crest
speed law + selfchecks, ±25 radius taper, schema-v2 `wave.amp` as per-vertex `aWaveA`,
colorspace law in the wall, TBN + matcap + dual detail, `sample(s,out)`) and this resuming
session, which closed out the lane's round-2 list:

- **Tint re-eyeball under the colorspace law: all six ART_BIBLE tints stand, `biomes.js`
  untouched.** The wash was the shader's round-1 constants, tuned on the raw framebuffer;
  post-law the rim flooded every grazing angle. Retuned in `wall_material.js` (rim pow/gain,
  both detail curves, sheen, matcap — values + rationale in-shader). Verified on a new
  six-biome contact sheet (`?lvl=biomes`, kept as permanent kit), the real L2 hiatus, and an
  arena interior; qa GREEN throughout. Evidence: `docs/shots/laneA/round2_tint_*.png` + two
  `*_retuned` frames.
- **Ruling #5 executed**: harness → `web/dev/laneA_world.html`, + `DBG.post()` to the house
  shot sink. `_fixture.js` stays — the spline selfcheck (qa gate) asserts against it; now
  documented in-file.
- **Stomach-arena shape read → C (task #7)**: recommend the spline-swept room (arena = "open"
  mode over an s-span, tube pipeline at room radii; fundus dome stays a welded icosphere;
  chained spheres rejected — crease rings + union collision math). Full argument in
  LANE_A_NOTES §→ Lane C; sketch `docs/shots/laneA/round2_stomach_arena_sketch.svg`. Triplanar
  deliberately skipped: the swept room would obsolete it where it matters.
- Housekeeping: `guts-a` dev server on 8145 in launch.json; sink 8144 reused.

Still open for A (round 3): swept-room implementation if C specs it, acid plane, villi band,
sphincter geometry, slug-map deletion on D's rename ping.

## 2026-07-16 · Round 1 — the canal, v0

Built `web/js/world/`: spline + parallel-transport frames + arclength LUTs, chunked streaming
tube, synthetic-scanner wall shader with vertex peristalsis, biome registry, arena shells v0,
noclip flycam, headless selfcheck, dev harness. Contract per TECH.md §THE WORLD CONTRACT,
drop-in for the stub.

**The game boots it.** `/?dbg=1` (no `?stub`) runs Lane A's world on C's `L2_esophagus`,
3600 units, hash `cefc4f83`, zero console errors. C's registry landing mid-round is what
unblocked `boot.js`'s `pickWorld()`; no shell change was needed.

Measured (dev.html, C's real L2 + D's real pack, 1920×1080, `renderer.info`):
draws **8** worst-frame over a full-canal sweep (budget ≤150) · tris **74,420** (≤500k) ·
geometries 6 → 6 across a full sweep and back, **no leak**, 0 after `dispose()` ·
load **<120 ms** (<2 s) · pinch ratio L2 3.32 / L3 1.89 (>1.5). fps deliberately **not**
claimed — the screenshot pane runs tabs hidden, which pauses rAF, and `gl.finish()` didn't
sync; needs a real window. Determinism: node and browser agree on the hash.

Three defects the checks caught that eyeballing would not have:
- **Tube folded through itself** on a wide+curvy join (turn radius 9.9 vs tube radius 17.2).
  Root cause: centreline amplitude authored in units. Fixed by solving amplitudes from a
  curvature budget, so `curviness` means "fraction of the pinch limit" and C can't author one.
- **Arena at 720 tris** — three's polyhedron `detail` is `20*(detail+1)^2`, not `20*4^detail`.
  Now solved for ~3u spacing from the arena's own radius.
- **Acid sea rendered as a black rectangle** — biome fog is tuned for 100u corridors, C's arena
  is 360u across. Arena fog is now sized to the room.

Also caught, and both would have rotted silently: the browser served a **stale cached
`biomes.js`**, so the first evidence set was shot at the old wave amplitude (re-shot); and D's
texture keys (`wall_smallint_a`) don't match my biome ids (`small_intestine`), which under the
assets-optional law fails to procedural forever with no error (slug map added, standardisation
proposed to D).

Decisions: peristalsis phase `K(s) = ∫k ds` with `k = OMEGA/flow(s)` ⇒ crest speed == local flow
(so "surf the crest" == "ride the current") · esophagus wave amp 0.9 → 1.4, measured, moves
`wallRho` for B · chunk seams align to biome joins, arenas own their span · one uv attribute,
tiling derived in-shader · colorspace left matching the stub, F to rule.

Evidence → `docs/shots/laneA/`: `round1_real_game_boot` (boot.js running Lane A's world),
`round1_L2_textured` / `round1_L2_procedural_fallback` (same pose, with and without D's pack —
the assets-optional law), `round1_L2_curve`, `round1_L2_wave_crest`, `round1_L3_arena_acid_sea`.

Open for round 2: triplanar arena shells + acid plane, villi band, normal/matcap TBN, sphincter
seam geometry. Full detail + per-lane asks in `LANE_A_NOTES.md`.