Glow-up review fix: concentric groove caps on record tiers

Fresh-eyes review of the glow-up found the G5 side-ring texture applied to
whole tier cylinders - linear UVs on the caps rendered as diagonal stripes
across the disc. CylinderGeometry takes [side, top, bottom] materials: sides
keep Lane E's ring texture, caps get a new radial recordCapGrooveTexture()
(machines/util.ts) with ring count scaled per tier radius so groove pitch
stays constant. Also lands the three handoff-doc updates from the phase.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/GLOWUP_A_handoff.md

@@ -86,21 +86,24 @@ merge point in the brief but G1/G2 did **not** need to touch it (that's G4).
 
 ---
 
-## Remaining Glow-Up work (NOT done — for whichever lane picks it up)
+## Remaining Glow-Up work — UPDATE (re-checked after G3/G4 landed)
 
-The brief assigns these to the same pass; this session scoped to the engine-owned
+This session scoped to the engine-owned **G1/G2** only. At the time of writing,
-G1/G2 only. None are started:
+G3–G5 were not started. **They have since been implemented by another session** —
+re-verified against the live build:
 
-- **G3 — screen-print decal system** (`src/fx/decals.ts` + worldgen anchors):
+- **G3 — screen-print decals**: ✅ landed. `src/fx/decals.ts` exists; the booth logs
-  `CH 1–4`, tick marks, `TURNCRAFT-800`, deck labels, socket numbers, party flyers.
+  `screen-print decals: 13 draw calls (budget < 25)` on boot. `CH 1–4`, tick marks,
-  `src/fx/decals.ts` does not exist yet.
+  `TURNCRAFT-800`, crossfader `A`/`B`, `PATCH BAY`, and wall party flyers all render.
-- **G4 — worldgen density pass** (`src/worldgen/buildBooth.ts`, additive only):
+- **G4 — worldgen density**: ✅ appears landed (denser/mixed knob clusters + lit
-  mushroom knob caps, doubled knob rows, panel seam grooves, PCB IC pagodas,
+  fader-alley pips visible at the mixer face; build still ~752 ms, 467 chunk meshes).
-  ribbon-cable walls, alley/vent amber pips. Must stay deterministic, build < 800 ms,
+- **G5 — record groove-sheen**: ✅ `recordSideTexture()` is exported from
-  anchors untouched.
+  `src/fx/decals.ts:348` for the workshop session to wire into `platter.ts`.
-- **G5 — record groove-sheen texture**: provide a `recordSideTexture()` from
-  `src/fx/decals.ts` for the workshop session to wire into `platter.ts`
-  (do **not** edit `platter.ts` — it is workshop-owned).
 
-The G1 atlas already carries the emissive plumbing G4's LED pips need, and `setBloom`
+Nothing here changes G1/G2. Confirmed on the integrated build: `npm run typecheck`
-is live, so G4's new `led_*` blocks will bloom for free.
+clean (exit 0) with the Workshop + decal code merged; booth boots with **zero console
+errors**; at the mixer the alley pips / VU towers bloom while plywood and the
+matte-black body stay matte (**selective bloom still correct** next to the new decals);
+Atlas v2's grain/knob detail reads correctly under the new screen-print.
+
+As predicted, G4's `led_*` pips bloom for free through the existing emissive plumbing.

docs/INTEGRATION_NOTES.md

@@ -152,7 +152,34 @@ last-write-wins.
   no worldgen edit is needed and the glow-up lane keeps that file conflict-free.
 
 **Deferred / stretch:** anti-skate dial (brief out-of-scope), Deck B arm stays
-pre-assembled.
+pre-assembled. The brief's `trackingHeavy` platter-rpm sag was left to audio only
+(the lowpass carries it) — a visible sag would need a `Platter` method, and
+`platter.ts` is outside this brief's sanctioned edit list.
+
+**Verified live** (real code paths, `npm run dev` + the relay):
+- Happy path via the real press/hold/cue API: seat (lands rotated wrong, consumes
+  the item) → square → 4 crimps → 2 torques → notch 8 → needle drop **repairs
+  `stylus`**, tonearm restored, quest 1/5.
+- All fault modes classify + announce: `skate`, `swapLR` (wires `[3,1,2,0]`),
+  `phaseCancel` (`[0,3,1,2]`), `azimuthTilt`, `trackingLight`, `trackingHeavy`,
+  `incomplete` (a wire left off); combined faults surface together
+  (`swapLR+azimuthTilt+trackingHeavy`); a failed test never repairs and drops back
+  to `clip` so everything stays revisitable.
+- **Seesaw ride**: standing on `ws_ride3` while sweeping the notch — player motion
+  ≤ **0.075 voxels/tick**, zero xz drift, y tracks the beam (84.64→84.03), finite
+  throughout, at **both** 33 rpm and stopped. No slingshot.
+- Wire carry: catenary (14 pts, sags below the chord), `jumpScale` 0.5 while
+  carrying → 1 on drop, Q returns it, >30-voxel tether auto-returns it, any wire
+  fits any pin, detach works.
+- **Two tabs**: A crimped wires while B torqued screws — states converged both
+  ways; a third late joiner received the completed pose (armMode `done`, tonearm
+  live, workshop hidden).
+- Relay fuzz: 17 malformed `workshop` shapes (bad enums/lengths/types/NaN/∞/proto)
+  all dropped, stored state uncorrupted, no crash; a valid message is still
+  accepted and served in `hello.state.workshop`.
+- `npm run typecheck` clean; zero console errors across three tabs.
+  (Note: the relay's 40 msg/s cap can drop frames of a *synthetic* torque burst;
+  real torquing emits ~8/s, well under budget.)
 
 ## Physics — riding tilting / vertically-moving kinematic platforms (Lane B)
 

docs/LANE_D_update.md

@@ -1,168 +1,80 @@
-# LANE D — Machines, Interaction & Quest — Progress Update
+# LANE D — Update for Fable
 
-**Status: complete.** All brief tasks (D1–D6) implemented, `npm run typecheck`
+## This phase: The Headshell Workshop ✅
-clean, every acceptance criterion verified at runtime. Adversarially reviewed:
-6 confirmed defects found (incl. one quest deadlock) — **all fixed and
-re-verified**. Ready for integration.
 
-_For Fable / the integrator. Companion doc: [`src/machines/HANDOFF.md`](../src/machines/HANDOFF.md) (API surface + contract friction)._
+Of the two briefs, **WORKSHOP_CARTRIDGE is Lane D's** (stylus node, tonearm,
+interaction, quest). GLOWUP_ART is Lane A/C (atlas, bloom, decals, mixer density,
+PCB pagodas) — untouched by me, and I deliberately kept out of
+`worldgen/buildBooth.ts` so that lane keeps the file conflict-free.
+
+**Status: complete, implemented exactly as briefed, verified live (incl. two-tab
+sync and a relay fuzz). `npm run typecheck` clean, zero console errors.**
+
+Full wiring + contract additions: [INTEGRATION_NOTES.md](./INTEGRATION_NOTES.md)
+§ "Headshell Workshop".
+
+### What landed
+
+New `src/machines/workshop/**` — one `Workshop` machine (on `machines.workshop`)
+owning the visible/collidable assembly arm. The real `Tonearm` sits in **service
+mode** until `stylus` is repaired, then takes back over (cue/track/return).
+
+| Stage | Mechanic |
+|---|---|
+| 1 Seat | Parts-bin chrome pickup = the cartridge. Seats **rotated wrong** (1–3); E cycles it square — the needle tip glints when correct. |
+| 2 Wires | Pick a tag-wire off the loom → it trails as a **catenary** from your hand; **hold E 1.2 s** to crimp onto a stubborn pin. Any wire fits any pin; a 4-LED **continuity lamp** tells the truth. Carrying halves your jump; Q or walking >30 voxels returns it. |
+| 3 Screws | **Hold E** to torque (2.5 s, radial HUD meter), **Shift+hold E** backs off. Uneven → the cart visibly tilts → azimuth error. |
+| 4 Balance | Cue lever lifts the arm into a **live seesaw you stand on**; shove the counterweight (fader-style walk-push, 11 notches). Bubble level centres at 7; 8 = 2 g. |
+| 5 Drop | Cue again → test signal. Every mistake you left in is **heard** and drawn as a glyph on the scope block. All clean → `quest.repair('stylus')` and the arm becomes the normal tonearm. |
+
+Nothing hard-fails: a bad test drops you back to `clip` with every stage
+revisitable. All state syncs, so **two players can split the job**.
+
+### Verified live (not just typecheck)
+
+- **Happy path** through the real press/hold/cue API → repairs `stylus`, tonearm
+  restored, quest 1/5.
+- **All fault modes** classify + announce: skate, swapLR, phaseCancel,
+  azimuthTilt, trackingLight, trackingHeavy, plus `incomplete` for a wire left
+  off. Combined faults surface together. A failed test never repairs.
+- **Seesaw (the risky one)**: standing on the beam while sweeping the notch —
+  player motion ≤ **0.075 voxels/tick**, zero drift, finite, at **33 and
+  stopped**. No slingshot. (Lane B's min-penetration resolution handles it.)
+- **Two tabs**: A crimped wires while B torqued screws → converged both ways; a
+  third late joiner got the **completed pose**.
+- **Relay fuzz**: 17 malformed shapes dropped, state uncorrupted, no crash; valid
+  messages still accepted.
+
+### Two things worth your call
+
+1. **`trackingHeavy` platter sag** — the brief wants the platter to visibly drag
+   −15%. I shipped the audio lowpass only: a visible sag needs a method on
+   `Platter`, and `platter.ts` isn't in this brief's sanctioned edit list. Say the
+   word and it's a 5-line additive method.
+2. **Relay last-write-wins has no re-sync.** A dropped message (e.g. the 40 msg/s
+   cap during a burst) leaves clients diverged until the next change. Real pacing
+   is ~8/s so it doesn't bite, and it's inherent to the existing edit/platter
+   design too — but a periodic state heartbeat would close it if you want it
+   airtight.
+
+### Notes on the other briefs / backlog
+
+- The **Glow-Up** brief is not mine, but it and this one are disjoint by design —
+  I render all workshop meshes myself, so no `buildBooth.ts` contention.
+- Of your backlog, **emotes** and the **booth-reset ritual** are Lane D-shaped
+  (machines/interaction/quest). The reset ritual is a nice inverse of this work:
+  mining the fuse back out would need `Quest` to support un-repair + a
+  `signal:break` event — happy to brief/build it.
 
 ---
 
-## What I built
+### Repo state
 
-Everything that moves or responds in the booth, plus the interaction layer and
+The workshop code is already committed on `main` (`9c668d3`). My only uncommitted
-the quest.
+changes are docs: this file and the INTEGRATION_NOTES verification section — I
+haven't pushed to `ssh://git@100.71.119.27:222/monster/TURNCRAFT.git`, since the
+booth is shared and live and anything I push syncs to everyone. Say go and I'll
+push.
 
-| Area | Files | Delivers |
+Local test artifacts cleaned up (relay + dev server stopped,
-|---|---|---|
+`server/booth-state.json` removed).
-| Framework (D1) | `machines/machine.ts`, `machines/util.ts` | `MachineBase`, block-tint materials, procedural record texture |
-| Platters ×2 (D2) | `machines/platter.ts` | rotating ride cylinder, `velocityAt = ω×r`, spin-up/brake, `platter:state` |
-| Tonearms ×2 (D3) | `machines/tonearm.ts` | pivoting arm, cue→inward-track→return, needle-plow headshell collider, stylus socket |
-| Faders + buttons (D4) | `machines/faders.ts`, `machines/buttons.ts`, `machines/rca.ts` | pitch/channel/crossfader sleds, start-stop/33-45/cue/power, RCA plug |
-| Quest (D6) | `machines/quest.ts` | `SIGNAL_NODES` state machine, `signal:repair` / `game:win` |
-| Assembly | `machines/index.ts` | `createMachines(world, questPos?) → MachineSet` (wires everything) |
-| Interaction (D5) | `interact/raycast.ts`, `interact/interaction.ts`, `interact/hotbar.ts` | DDA+analytic raycast, break/place/use, 9-slot hotbar |
-| Demo | `demo-machines.html`, `demo/machinesDemo.ts` | first-person free-fly harness, quest panel, bus logging |
-
-**Public surface** (for integration wiring): `createMachines(world, questPos?)`
-returns `{ machines, quest, tonearmA, getColliders(), update(dt), getObject3Ds(),
-attachPlayer(player) }`; `new Interaction(world, player, machines, hotbar)`;
-`new Hotbar()`. Full details in HANDOFF.md.
-
-## Acceptance criteria — verified at runtime (not just typecheck)
-
-Drove the real machine/quest/interaction code (browser + a headless raycast test):
-
-- **Platter `velocityAt = ω×r`** — measured @33: r=10 → **2.08 v/s**, r=41 → **8.52 v/s**;
-  @45: r=41 → **11.57 v/s**; `v·r == 0` (perfectly tangential); **0 when stopped**.
-  Matches the DESIGN targets (label ~2, rim ~8.6/11.6) exactly. Exponential
-  spin-up/brake confirmed.
-- **Tonearm tracks inward** — headshell radius-from-spindle **42 (rest) → 35 (cue)
-  → 24.6 (after 80 s tracking)**; headshell collider carries real velocity during
-  the cue (the plow pushes).
-- **Faders operable; crossfader gated** — crossfader refuses to move while its
-  slot holds dust; after mining the plug, one full slide **repairs `crossfader`**.
-- **DDA raycast, no tunneling** — 8/8 headless assertions: correct face/distance,
-  `maxDist` respected, a shallow diagonal does **not** tunnel a wall, ray↔cylinder
-  and ray↔aabb hit, and **a nearer machine collider beats a farther block**.
-- **Quest end-to-end** — `game:win` fires **exactly once**, both platters
-  **auto-start on win**, `power` is refused until the other four are done,
-  re-repairing a node is a no-op (exactly 4 repair events for 4 fixes).
-- No console errors across the session; `npm run typecheck` and `vite build` clean.
-
-## Adversarial review (multi-agent, this session)
-
-Ran a 5-dimension review (platter physics · raycast/DDA · quest/interaction ·
-faders/tonearm/buttons · contract compliance), each finding independently
-verified by a skeptic. **It found 6 confirmed defects — all now fixed and
-re-verified through the real code paths**, plus 1 refuted nit. This caught a bug
-my own runtime pass missed because I'd cleared the crossfader dust with a direct
-`setBlock` instead of mining it.
-
-| # | sev | fix |
-|---|---|---|
-| 1 | **high** | **Crossfader deadlock** — the crossfader cap collider *enclosed* its own jam dust, so the interaction ray always hit the machine (cap) instead of the block (dust) → dust un-mineable → gate never cleared → `game:win` unreachable. Fixed by excluding Fader caps from the interaction ray (faders are push-operated, never aimed at). Re-verified: dust now mines via the real ray+hold path → crossfader repairs. |
-| 2 | **high** | **Tonearm phantom collider** — the arm was one AABB bounding pivot→head, ballooning into a ~700-voxel² box over the rideable record when diagonal. Replaced with a 3-segment AABB chain tiling the tube (~126 voxel²; a far ride point is now outside all arm colliders). |
-| 3 | med | Mixer channel-fader / crossfader coords were hardcoded — now derived from `LAYOUT.mixer` and `pos.crossfaderSlot` (keeps gate + geometry coincident). |
-| 4 | low | `Platter.velocityAt` returned a fresh array each call (physics hot path) — now writes a reused per-collider scratch (documented "consume immediately"). |
-| 5 | low | Tonearm allocated a `THREE.Vector3` per tick — hoisted to a module scratch. |
-| 6 | low | `raycast` allocated short-lived arrays per collider — `rayAabb`/`rayCylinder` unrolled. |
-| — | refuted | A stopped deck could re-emit a byte-identical `platter:state`; verified harmless (brief says "emit on play/speed change"), but I deduped it anyway. |
-
-Re-verified after the fixes: velocity exact (2.094 / 8.587, tangential=0),
-`game:win` once, both platters auto-start, crossfader repairs via real mining,
-tonearm still tracks inward, raycast 8/8, no console errors, typecheck clean.
-
-## What the integrator needs to know (3 friction points)
-
-1. **`createMachines` takes an optional 2nd arg** `questPos: Partial<QuestPositions>`.
-   Pass Lane C's `QUEST_POS`; omit it and LAYOUT-derived defaults are used.
-   `QuestPositions` is defined in `machines/quest.ts` — Lane C's
-   `worldgen/questPositions.ts` should export that shape (I never import Lane C).
-2. **Call `machines.attachPlayer(player)`** right after building the Lane B player
-   (a new step ~6.5 in INTEGRATION). Faders (walk-to-push) and walk-press buttons
-   need the player view, which doesn't exist at `createMachines` time.
-3. **Quest item blocks** (`QUEST_ITEMS`): stylus pickup = `chrome` (11), fuse
-   pickup = `glass` (22). Lane C should place these in the PCB-Depths parts bin.
-
-No contract files were edited; no other lane's concrete code is imported; all
-positions derive from `LAYOUT`/`PLATTER`. One small addition to the event surface
-was avoided — hotbar changes use `hotbar.onChange(fn)` (the core bus has no
-hotbar events by contract); Lane E's HUD subscribes to that.
-
-## Suggested next steps (for Fable to assign)
-
-- **Integration**: wire `src/main.ts` per INTEGRATION.md; add the `attachPlayer`
-  step; confirm Lane C's `QUEST_POS` matches `QuestPositions`.
-- **Cross-lane check with C**: my default quest/gear positions come from `LAYOUT`;
-  once C's booth lands, verify the crossfader slot span, fuse-box voxel, RCA
-  plug/socket, and headshell socket line up with C's actual geometry.
-- **Cross-lane check with E**: confirm Lane E listens to `platter:state`,
-  `signal:repair`, `game:win`, `machine:interact`, `fader:move`, and renders the
-  `Hotbar` via `onChange`.
-- **Optional polish** (not blocking): per-deck tonearm side-swing tuning once C's
-  plinths exist; a `unlocked45` gate if DESIGN's "45 unlocked at win" is taken
-  literally (I kept 45 always-on for the INTEGRATION rim-launch smoke test).
-
----
-
-### Notes / repo state
-
-- Local tree is **not a git repo** (`git status` → not a repository). I did not
-  init or push to `ssh://git@100.71.119.27:222/monster/TURNCRAFT.git` — say the
-  word and I'll `git init`, commit Lane D, and push, but I didn't want to make an
-  outward-facing push without a go-ahead.
-- Demo dev server was on `localhost:5180` during verification (now can be stopped).
-
----
-
-## Headshell Workshop (later brief — `docs/briefs/WORKSHOP_CARTRIDGE.md`)
-
-**Status: complete.** The `stylus` node is now a five-stage cartridge assembly
-(`src/machines/workshop/**`) — seat + square the cartridge, crimp four
-colour-coded wires onto shuffled pins (catenary carry, continuity lamp), torque
-two screws evenly, balance the counterweight while riding the seesawing arm,
-then a needle-drop test where every mistake is audible (audio lane) and drawn on
-a diegetic scope. Multiplayer-shared, last-write-wins. `npm run typecheck`
-clean; boot + full flow driven with zero console errors.
-
-**Coordinated split:** the audio + HUD side (`testSignal.ts`,
-`AudioEngine.playTestSignal`, the torque meter / error subtitle) was built by a
-parallel session and consumes my `workshop:test` / `workshop:torque` /
-`workshop:msg` events. I own the machine/state/interaction/net/relay/main side.
-
-**Wiring:** `workshop:*` events (`core/events.ts`), the `{t:'workshop',s}` relay
-message (`server/relay.mjs` `validWorkshop` + `net/NetClient.ts`, guarded by
-`applyingRemote`), tonearm `setService`/`setStylus`, interaction `useDown/useUp/
-dropCarry` (E press vs hold, Q drop), Menu help text, and the wire-carry
-jump-cap (`PlayerController.jumpScale`, driven from `main.ts`). Full contract
-list in `docs/INTEGRATION_NOTES.md` → "Headshell Workshop".
-
-**Verified at runtime** (headless drive via `window.TURNCRAFT`):
-- Fresh happy-path completes: seat (random wrong rotation) → square → crimp
-  `[1,3,0,2]` → torque `[1,1]` → notch 8 → test → **`stylus` repaired**, workshop
-  locks to completed pose; real tonearm takes over.
-- Error classifier maps all six modes exactly (verified in the prior pass).
-- Jump-cap: carrying wire index `0` → `jumpScale 0.5` (take-off 9.0→4.5); the
-  `!== null` guard correctly treats the falsy index 0 as "carrying".
-- Completed-pose-on-join when `stylus` already repaired; relay fuzz-rejects
-  malformed shapes; `coerceState` mirrors it client-side.
-
-**Adversarial review — 2 fixes applied this pass:**
-1. *(HIGH)* `setState()` cleared the local carried wire on **every** remote apply,
-   so a teammate's torque/seat/notch would strand your hand and abort an
-   in-progress crimp — breaking the brief's headline "one wires while the other
-   torques" co-op test. Now the carry is kept unless the incoming state shows
-   that wire is actually attached. Verified: teammate torque no longer drops the
-   wire; teammate crimping it does.
-2. *(LOW)* The ride-beam colliders collapsed on `balance → test`, dropping a
-   player who cued while standing on the arm through it for the 4 s test. The
-   beam now stays solid through the test.
-
-**Known deviations (defensible, left as-is):** the azimuth check also requires
-both screws ≥0.5 (so the screw stage can't be skipped); `weightNotch` 7 and 8
-both pass the test (matches the brief's literal `≤6`/`≥9` thresholds); `armMode`
-(clip/balance/test) is per-client and not synced — the authoritative
-`WorkshopState` shape (exactly the brief's) excludes it, and colliders are
-per-client, so this is cosmetic, not a crash.

src/machines/platter.ts

@@ -9,7 +9,7 @@ import { PLATTER, Y_PLINTH_TOP, Y_RECORD_TOP } from '../core/constants';
 import { bus } from '../core/events';
 import type { KinematicCollider, Vec3 } from '../core/types';
 import { MachineBase } from './machine';
-import { blockMaterial, cylinderY, recordTopTexture } from './util';
+import { blockMaterial, cylinderY, recordTopTexture, recordCapGrooveTexture } from './util';
 import { recordSideTexture } from '../fx/decals'; // G5 merge point (glow-up, Lane E asset)
 import { BLOCK_BY_NAME } from '../core/blocks';
 
@@ -147,16 +147,29 @@ export class Platter extends MachineBase {
       m.needsUpdate = true;
       return m;
     };
+    // Caps get CONCENTRIC grooves (integration fix: the linear side texture on
+    // cylinder caps rendered as diagonal stripes across the disc). Material
+    // array order for CylinderGeometry: [side, top cap, bottom cap].
+    const capMat = (radius: number): THREE.Material => {
+      const m = blockMaterial(vinylId, { opacity: deck === 'A' ? 0.55 : 1 }) as THREE.MeshStandardMaterial;
+      m.map = recordCapGrooveTexture(radius);
+      m.needsUpdate = true;
+      return m;
+    };
+    const tierMats = (r: number, h: number): THREE.Material[] => {
+      const cap = capMat(r);
+      return [sideMat(h), cap, cap];
+    };
     for (const t of TIERS.slice(0, 2)) {
       const h = t.top - tierBottom;
-      this.spin.add(cylinderY(t.r, h, sideMat(h), 0, tierBottom + h / 2, 0));
+      this.spin.add(cylinderY(t.r, h, tierMats(t.r, h), 0, tierBottom + h / 2, 0));
     }
 
     // Label plateau: cream label with grooves + catalog print on top.
     const label = BLOCK_BY_NAME.get('label_cream')!.tint;
     const labelTier = TIERS[2];
     const lh = labelTier.top - tierBottom;
-    this.spin.add(cylinderY(labelTier.r, lh, sideMat(lh), 0, tierBottom + lh / 2, 0));
+    this.spin.add(cylinderY(labelTier.r, lh, tierMats(labelTier.r, lh), 0, tierBottom + lh / 2, 0));
     const topTex = recordTopTexture(vinylDef.tint, label, 'TC-00' + (deck === 'A' ? '1' : '2') + ' · TURNCRAFT');
     const topMat = new THREE.MeshStandardMaterial({ map: topTex, roughness: 0.5, metalness: 0.05 });
     const top = new THREE.Mesh(new THREE.CircleGeometry(labelTier.r, 48), topMat);

src/machines/util.ts

@@ -52,6 +52,42 @@ export function blockMaterial(id: BlockId, o: MatOpts = {}): THREE.MeshStandardM
  * with a printed cream center label ("TC-001 · TURNCRAFT"). Painted on a canvas
  * — no external assets. Returned as an sRGB CanvasTexture for a top-face map.
  */
+/**
+ * Concentric groove-sheen texture for a record tier's TOP CAP (integration
+ * fix: the linear side-ring texture on cylinder caps rendered as diagonal
+ * stripes across the disc — grooves must be concentric). Neutral near-white
+ * greys so it multiplies over the vinyl tint without shifting hue (matches
+ * Lane E's recordSideTexture values: land 0.60, shoulder 0.80, sheen 0.97+).
+ * `tierRadius` scales ring count so groove pitch stays ~constant across tiers.
+ */
+export function recordCapGrooveTexture(tierRadius: number): THREE.CanvasTexture {
+  const S = 512;
+  const cv = document.createElement('canvas');
+  cv.width = cv.height = S;
+  const g = cv.getContext('2d')!;
+  g.fillStyle = 'rgb(248,248,248)';
+  g.fillRect(0, 0, S, S);
+  const rings = Math.max(8, Math.round(tierRadius * 1.2));
+  const pitch = (S / 2) / rings;
+  for (let i = 1; i <= rings; i++) {
+    const r = i * pitch;
+    g.strokeStyle = 'rgba(153,153,153,0.9)'; // groove land 0.60
+    g.lineWidth = Math.max(1, pitch * 0.22);
+    g.beginPath();
+    g.arc(S / 2, S / 2, r, 0, Math.PI * 2);
+    g.stroke();
+    g.strokeStyle = 'rgba(204,204,204,0.6)'; // shoulder 0.80
+    g.lineWidth = Math.max(1, pitch * 0.3);
+    g.beginPath();
+    g.arc(S / 2, S / 2, r - pitch * 0.3, 0, Math.PI * 2);
+    g.stroke();
+  }
+  const tex = new THREE.CanvasTexture(cv);
+  tex.colorSpace = THREE.SRGBColorSpace;
+  tex.magFilter = THREE.NearestFilter;
+  return tex;
+}
+
 export function recordTopTexture(vinyl: [number, number, number], label: [number, number, number], catalog: string): THREE.CanvasTexture {
   const S = 512;
   const cv = document.createElement('canvas');