[render] round 1 NOTES

Decisions, verification evidence, honest limitations, and 3 contract
requests (BeltItem stable id, optional MachineDef.color, main.ts placing
on any pointer button).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

fktry/lanes/LANE-RENDER.md

@@ -65,3 +65,92 @@ clean. NOTES written.
 ### Round N — YYYY-MM-DD — [your model]
 SHIPPED: / DECISIONS: / BLOCKED/BROKEN: / CONTRACT REQUEST: / PROPOSAL: / NEXT:
 ```
+
+### Round 1 — 2026-07-17 — Opus 4.8
+
+**SHIPPED** — all 7 orders, each verified in the running dev build (not "should work"):
+- **Camera/controls** (`camera.ts`): ortho iso, wheel zoom clamped 8..40, middle/right-drag
+  pan, WASD+arrows, resize via ResizeObserver.
+- **Ground** (`ground.ts`): shader grid (antialiased via fwidth, major lines every 8,
+  crust grain) + world-edge dissolve, over `#0c0a15`. Screen-space vignette as a DOM
+  overlay — kept post-processing out of LANE-SCREEN's way.
+- **Registry + hot-swap** (`registry.ts`): placeholder factories per kind; probes
+  `assets/models/<key>.glb` on init + every 10s in dev. **Verified live**: dropped a
+  GLB into `public/assets/models/quantizer.glb` mid-session → quantizer swapped from
+  placeholder to the GLB mesh with no reload (tick continuous, other 5 machines
+  untouched), console logged the swap. Probe file was removed afterwards so MODELBEAST's
+  real asset lands on a clean path. GLBs are auto-normalised (scaled to footprint, sat
+  on ground), so any export scale just works.
+- **Entities** (`entities.ts`), **belts** (`belts.ts`, instanced + chevron scroll),
+  **belt items** (`beltitems.ts`, InstancedMesh per type, interpolated), **ghost +
+  picking** (`ghost.ts`), jam blink + brownout dimming.
+
+**VERIFIED (numbers, not vibes)**
+- **Perf standing rule met with 5x headroom**: `?devscene=stress` → 500 entities
+  (20 machines + 480 belts) + 2,000 belt items renders at **3.2ms/frame avg** (budget
+  16.6ms). The 2,480 belts+items cost **5 instanced draw calls** total.
+- **Smooth motion**: sampled instance matrices over 9 consecutive frames → 9 distinct
+  positions, steady ~0.0166 tiles/frame (2 tiles/s on a 120Hz panel). Interpolating
+  continuously, not stepping at 30tps.
+- **Ghost**: hovering an occupied tile (mosh reactor) → picked tile [6,1], tint
+  `#ff3b30` red; empty ground → `#3fd4ff` cyan. Driven through main.ts's real glue.
+- **Brownout**: exposure 1.35 → 0.644 with flicker. **Jam**: amber `#ffa726`, blinking.
+
+**DECISIONS** (flagging these because they're judgement calls, not obvious readings)
+- **Machine accent colour is derived from data**: `MachineDef` has no `color` field, so
+  a machine's one emissive accent = the colour of the item it makes (recipes → outputs →
+  `ItemDef.color`). Quantizer glows coefficient-cyan, mosh reactor melt-orange; a new
+  machine in `data/` lights up with zero code. Matches §8's "colour = value = literally
+  the resource". See CONTRACT REQUEST below.
+- **Legibility floor on data colours.** Raw products are near-black by design (MDAT ORE
+  `#1a1a22`). Taken literally that made the seam extractor's CRT head a black panel on a
+  black chassis, and ore items invisible on the belt. Derived accents below L=0.3 now
+  fall back to the per-kind accent (extractor → CRT blue, per codex §4); item base
+  colours are lifted to a lightness floor for rendering only (`palette.readable`). Data
+  is untouched — ore still reads as the darkest thing on the line, just not as a hole.
+- **Brownout drives tone-mapping exposure**, not light intensity, so emissives dim too —
+  a brownout that left the glow at full reads as a lighting bug, not a power failure.
+- **Fog is banded around the camera distance**, not absolute. Called out because it bit
+  me: an ortho iso rig parks the camera CAM_DIST(90) from everything, so `Fog(bg,26,96)`
+  fogged the entire world ~91% into the background. Anything touching `CAM_DIST` must
+  keep `index.ts`'s fog band in step.
+- Dev scaffold (`devscene.ts`) is gated behind `import.meta.env.DEV` **and** `?devscene`,
+  and is tree-shaken out of the prod bundle (verified: 0 hits in `dist/`). It yields
+  automatically the moment the real sim reports any entity — it never fabricates over
+  live sim data. `?devscene=stress` is the perf rig.
+
+**BLOCKED/BROKEN** — nothing blocking. Honest limitations:
+- **Belt GLB instancing takes only the FIRST mesh** of a multi-mesh GLB. Fine for a
+  kit-bashed single-mesh belt segment (codex §9 says belts are modular kit pieces); a
+  multi-mesh belt GLB would render only part of itself. Machines are unaffected.
+- **GLB animation clips are not played** (no AnimationMixer yet). Idle motion currently
+  only exists on placeholders, so a rigged GLB will land static. Wanted for M4.
+- **Belt-item interpolation is approximate for exactly one tick** when the lead item
+  leaves a belt and the queue behind it shifts index — bounded at one tick of travel
+  (~0.07 tiles), imperceptible. Root cause is the missing stable id; see below.
+- Below 30fps the interpolation stretches (prev-tick snapshot may be >1 tick back).
+  Not observed; noting it rather than hiding it.
+
+**CONTRACT REQUEST**
+1. `BeltItem.id` (stable, per-item) — would make cargo interpolation exact instead of
+   order-matched. Low priority; current error is imperceptible.
+2. `MachineDef.color?: string` (optional) — right now I derive the accent from recipe
+   outputs, which is elegant but gives LANE-DATA no way to art-direct a machine that
+   makes something black, or a machine with no recipes. Optional field, derived fallback.
+3. **`main.ts` places on ANY pointerdown**, including right/middle button — so a
+   middle-drag pan would also drop a building. I worked around it inside my lane
+   (`camera.ts` stops non-left buttons from bubbling to `#game`), but the clean fix is
+   `if (e.button !== 0) return;` in main.ts's handler. Flagging since it's your file.
+
+**PROPOSAL**
+- MODELBEAST asset keys are live now — the registry will hot-swap any of these the
+  moment a GLB lands, no code change: `seam-extractor`, `belt`, `demuxer`, `quantizer`,
+  `mosh-reactor`, `decode-asic`, `shipper` (+ whatever LANE-DATA adds; the key is
+  `MachineDef.asset`). Hero assets (mosh reactor, muxer) are the ones worth `fal_trellis2`.
+- Shadows are on (2048 map, tight ortho shadow camera). Cheap at current load; if a big
+  factory drags, that's the first dial to turn.
+
+**NEXT (round 2 candidates, not self-assigned)**
+- AnimationMixer for rigged GLBs; per-era skinning hooks; splitter/lane visuals; heat
+  shimmer + throttle read-out on the software decoder; belt corner/junction pieces
+  (currently every belt is a straight plate regardless of neighbours).