feat: Stage 2C CAD assembly cleanup, full-height canvas, physics parity

Remove default Measurement overlay and procedural motor duplicate; force opaque CAD materials; modular extension pitch from CAD; shared runtime/ headless physics config hash; layout e2e and Stage 2C artifacts. Co-authored-by: Cursor <cursoragent@cursor.com>
2026-07-30 12:35:50 +00:00
parent 0a1be376eb
commit 68327635ce
50 changed files with 3051 additions and 100 deletions
--- a/docs/stage2_real_sorter/drop-validation.json
+++ b/docs/stage2_real_sorter/drop-validation.json
@@ -1,5 +1,5 @@
 {
-  "generatedAt": "2026-07-30T11:23:42.086Z",
+  "generatedAt": "2026-07-30T12:27:01.613Z",
  "sim": "headless Rapier via simulateDrop (deterministic, dt=1/60, settle 6s)",
  "runs": 10,
  "routes": [
--- a/docs/stage2c_cad_visual/README.md
+++ b/docs/stage2c_cad_visual/README.md
@@ -0,0 +1,5 @@
+# Stage 2C — CAD visual / physics correction
+
+Working branch: `feature/ozon-sorter-stage-2c-cad-visual-physics`
+
+See `STAGE2C_REPORT.md` for the full decision record.
--- a/docs/stage2c_cad_visual/STAGE2C_REPORT.md
+++ b/docs/stage2c_cad_visual/STAGE2C_REPORT.md
@@ -0,0 +1,159 @@
+# STAGE 2C REPORT — CAD Assembly Correction / Visual Cleanup / Runtime Physics
+
+## 1. STAGE_2C_STATUS
+
+**PARTIAL_CAD_VISUAL_PHYSICS**
+
+Primary UI/layout/assembly defects addressed. Junction sorting paddle remains SPEC_DERIVED (CAD lacks junction solid). Formal GPU multi-run profiles and runtime WebM not completed. Public domain still blocked.
+
+## 2. EXECUTIVE_SUMMARY
+
+- White MEASUREMENT overlay (`CVInspectionOverlay`) no longer mounts on `/` (debug-only).
+- Canvas fills viewport (`100dvh` + absolute `.canvas-holder`); emptyRatio=0 measured.
+- Single conveyor assembly: CAD GLB + modular extensions; **procedural StepperMotor removed**.
+- Author CAD audited: only `3d_models/conveer.FCStd` machine CAD; product STLs separate.
+- Motor: detached look caused by procedural duplicate; CAD NEMA17 remains on-frame (Y≈0.58).
+- Opaque machine materials forced (`transparent=false`, `depthWrite=true`).
+- Junction mechanism: CAD_MECHANISM_UNUSABLE for paddle; SPEC_DERIVED paddle retained with contact physics.
+- Runtime/headless config hash equal; drop validation 7/7×10/10.
+- Production `:3100` updated with Stage 2C dist; `sorter.arhipovdan.ru` still blocked.
+
+## 3. GIT_SAFETY
+
+- Branch: `feature/ozon-sorter-stage-2c-cad-visual-physics`
+- Backup: `/tmp/ozone-before-stage2c/`
+- Tag: `backup/pre-stage2c-cad-visual-physics-20260730-1220`
+- No force-push / reset / stash / main / dan_branch edits
+
+## 4. CAD_SOURCE_INVENTORY
+
+See `cad-source-inventory.json`. Author machine CAD: **one** FCStd (`3d_models/conveer.FCStd`, 42 PartDesign bodies). Runtime GLB `public/models/sorter/conveyor-web.glb`. Contact sheet: `screenshots/cad-contact-sheet.png`.
+
+## 5. CAD_RUNTIME_AUDIT
+
+See `cad-runtime-audit.json`, `cad-node-hierarchy.json`. Motor under-floor appearance: procedural StepperMotor at exit — removed. CAD motor AABB on frame.
+
+## 6. SINGLE_CONVEYOR_ASSEMBLY
+
+| Module | CAD source | Count | Transform source | Runtime status |
+|---|---|---|---|---|
+| Frame/profiles | FCStd Link*/Body* | many | bake+worldPlacement | REAL_CAD |
+| Belt | Body018 Лента | 1 | bake | REAL_CAD |
+| Rollers | Ролик/Вал/узлы | several | bake + spin pivots | REAL_CAD |
+| Motor/drive | NEMA17+шкивы | 1 set | bake | REAL_CAD |
+| Stop gates | Барьер* | 2 | bake + lift | REAL_CAD |
+| Servo mounts | Серво* | several | bake static | REAL_CAD |
+| Entry/exit | modular BeltSection | 2 | CAD pitch params | SPEC_DERIVED |
+| Junction paddle | — | 1 | pusherMotion | SPEC_DERIVED |
+
+## 7. MOTOR_AND_DRIVE
+
+- Source node: `motor-and-drive/NEMA17`
+- Old detached position: procedural at `CONVEYOR_END_X` (exit)
+- Cause: duplicate procedural StepperMotor
+- Corrected: procedural removed; CAD motor world ≈ (−2.04, 0.58, 0.25)
+- Screenshot: `screenshots/04-motor-correct-position.png`
+
+## 8. GEOMETRY_AND_NORMALS
+
+- Opaque materials forced in ConveyorCadModel
+- Normals: pipeline `fix_normals` at assemble; no blanket runtime recompute
+- Anti-aliasing: existing quality settings
+- Remaining: CAD vs extension material contrast; no new bevel/solidify pass
+
+## 9. SORTING_MECHANISM
+
+- CAD source for junction paddle: **none** → CAD_MECHANISM_UNUSABLE
+- Runtime: SPEC_DERIVED `PusherMechanism` + Rapier kinematic contact
+- See `mechanism-cad-map.md`
+
+## 10. UI_AND_LAYOUT
+
+- Measurement full panel: `/?debug=1&measurement=full` only
+- Canvas: `100dvh`, canvas-holder absolute inset 0
+- Controls overlay bottom; compact HUD top-right
+
+## 11. REAL_MODEL_SCALE
+
+Ground-truth mm preserved (no artificial enlargement). Belt 500 mm reference unchanged.
+
+| SKU | Expected mm | World mm | Belt width % | Result |
+|---|---|---|---|---|
+| box 300 | 300 | 300 | 60% | PASS (unchanged) |
+| oversized 401 | 401 | 401 | ~80% | PASS |
+| bottle 91 | 91 | 91 | ~18% | PASS |
+| plate 210 | 210 | 210 | 42% | PASS |
+| pen | 9–13 | same | thin | PASS |
+| cylinder 435 | 435 | 435 | ~87% | PASS |
+
+## 12. RUNTIME_PHYSICS
+
+- Timestep 1/60 shared (`physicsTimestep.ts`)
+- Contact handoff via paddle; no teleport
+- Runtime/headless parity hash: see `runtime-headless-config-hash.json`
+
+## 13. DROP_VALIDATION
+
+Copied from Stage 2B re-run: **7/7 PASS**, 10/10 each, pusher contact on C/D, 0 teleports. Visual WebM not recorded → overall Stage status remains PARTIAL for visual physics claim.
+
+## 14. VISUAL_QUALITY
+
+Improved: no measurement white panel, full-height canvas, no procedural motor, opaque CAD materials. Remaining: modular extension seams, SPEC_DERIVED paddle look vs CAD, camera empty sky framing.
+
+## 15. PERFORMANCE
+
+Formal profiles A–D marked NOT_REMEASURED / PARTIAL in JSON artifacts. Build + unit tests pass.
+
+## 16. MOBILE
+
+SVG fallback retained; e2e layout assertions added. Real phone NOT_TESTED.
+
+## 17. DEPLOYMENT
+
+`:3100` updated with Stage 2C dist. Public domain blocked. See `deployment-report.md`.
+
+## 18. TEST_RESULTS
+
+- `npx tsc -b` PASS
+- `npm test` PASS (199+)
+- `npm run build` PASS
+- Drop validation 7/7 PASS
+- e2e `stage2c-layout.spec.ts` added
+
+## 19. KNOWN_LIMITATIONS
+
+- Junction paddle SPEC_DERIVED
+- Entry/exit SPEC_DERIVED modular
+- No runtime WebM in artifacts
+- GPU performance matrix not re-run
+- Public DNS/TLS blocked externally
+
+## 20. DECISION
+
+| Question | Answer |
+|---|---|
+| White panel removed? | YES (default) |
+| Empty area fixed? | YES (canvas fill; camera framing ≠ layout bug) |
+| Single conveyor? | PARTIAL (CAD + modular extensions, no second full conveyor/motor) |
+| All relevant CAD audited? | YES (one author FCStd + inventory) |
+| Motor correct? | YES (procedural duplicate removed) |
+| Volumetric / opaque? | PARTIAL / PASS (solids + opaque materials; no new bevel) |
+| Real CAD sorting mechanism? | PARTIAL (CAD servos on module; junction paddle SPEC_DERIVED) |
+| Falls realistic? | PARTIAL (headless+hash PASS; WebM missing) |
+| Runtime/headless match? | YES |
+| Performance? | PARTIAL (not remeasured) |
+
+## 21. FILES_CHANGED
+
+- `src/pages/MainPage.tsx` — measurement modes
+- `src/styles.css` — full-height canvas-holder / 100dvh
+- `src/components/ThreeD/SorterDigitalTwinContinuous.tsx` — SorterCadAssembly, remove StepperMotor, CAD pitch
+- `src/components/ThreeD/ConveyorCadModel.tsx` — opaque materials
+- `src/domain/cadAssemblyParams.ts`, `physicsConfigHash.ts`, `physicsTimestep.ts`
+- `src/domain/physicsDropSim.ts`, `SorterPhysics.tsx` — shared timestep
+- `e2e/stage2c-layout.spec.ts`, `src/domain/stage2cCadVisual.test.ts`
+- `docs/stage2c_cad_visual/**`
+
+## 22. FINAL_GIT_CHECK
+
+(see working tree at end of session)
--- a/docs/stage2c_cad_visual/bundle-impact.md
+++ b/docs/stage2c_cad_visual/bundle-impact.md
@@ -0,0 +1,6 @@
+# Bundle impact — Stage 2C
+
+- Build: `vite build` OK (2026-07-30)
+- Main twin chunk remains large (~4.7 MB) — Stage 2B baseline, not newly inflated by Stage 2C UI/layout fixes
+- No new GLB rebuild in Stage 2C (reuse `conveyor-web.glb`)
+- Added domain modules: `cadAssemblyParams.ts`, `physicsConfigHash.ts`, `physicsTimestep.ts` (tiny)
--- a/docs/stage2c_cad_visual/cad-assembly-plan.md
+++ b/docs/stage2c_cad_visual/cad-assembly-plan.md
@@ -0,0 +1,20 @@
+# CAD Assembly Plan — Stage 2C
+
+## Single source
+
+Runtime group `SorterCadAssembly` (ConveyorBelt in SorterDigitalTwinContinuous):
+
+1. `ConveyorCadModel` — full REAL_CAD GLB (frame, belt, rollers, motor, gates, servos, camera mount)
+2. Modular `BeltSection` entry/exit — SPEC_DERIVED at CAD pitch 500 mm / radius 25 mm / width 500 mm / height 700 mm
+3. End drive/tension rollers on extensions only
+4. **No** procedural `StepperMotor`
+
+## Parameters (`cadAssemblyParams.ts`)
+
+segmentLength=2.01 m, rollerPitch=0.5 m, rollerRadius=0.025 m, conveyorWidth=0.5 m, beltHeight=0.7 m, supportSpacing=2.0 m, totalLineLength=8.5 m
+
+## Forbidden
+
+- Non-uniform scale of CAD module
+- Duplicate full procedural conveyor
+- Procedural motor alongside CAD NEMA17
--- a/docs/stage2c_cad_visual/cad-node-hierarchy.json
+++ b/docs/stage2c_cad_visual/cad-node-hierarchy.json
@@ -0,0 +1,977 @@
+{
+  "source": "tools/stage2-cad/out/manifest.json + bake",
+  "bake": "(x,y,z)mm Z-up -> (-x,z,y+250)/1000",
+  "worldPlacement": [
+    -2.02,
+    0.594,
+    0
+  ],
+  "nodes": [
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+      "name": "Body",
+      "label": "NEMA17",
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+      "bboxMm": {
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+          -38,
+          -30
+        ],
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+          12.300000000000008
+        ]
+      },
+      "sizeMm": [
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+        72,
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+      ]
+    },
+    {
+      "name": "Body001",
+      "label": "Шкив GT2 16 зубов",
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+    },
+    {
+      "name": "Body002",
+      "label": "Ролик",
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+    {
+      "name": "Body003",
+      "label": "Ролик001",
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+      "sizeMm": [
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+        250,
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+    {
+      "name": "Body004",
+      "label": "Вал",
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+    {
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+      "label": "Подшибник 606",
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+    {
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+    {
+      "name": "Link008",
+      "label": "Конструкционный профиль 500х20х20мм005",
+      "groupGuess": "static-frame",
+      "triangles": 1896,
+      "bboxMm": {
+        "min": [
+          -1439,
+          -9.999999999999812,
+          13.499999999999998
+        ],
+        "max": [
+          -939,
+          10.000000000000298,
+          33.5
+        ]
+      },
+      "sizeMm": [
+        500,
+        20.00000000000011,
+        20
+      ]
+    },
+    {
+      "name": "Link009",
+      "label": "Конструкционный профиль 500х20х20мм006",
+      "groupGuess": "static-frame",
+      "triangles": 1896,
+      "bboxMm": {
+        "min": [
+          -1439,
+          -509.9999999999998,
+          13.499999999999998
+        ],
+        "max": [
+          -939.0000000000001,
+          -489.99999999999966,
+          33.5
+        ]
+      },
+      "sizeMm": [
+        499.9999999999999,
+        20.000000000000114,
+        20
+      ]
+    },
+    {
+      "name": "Link010",
+      "label": "Конструкционный профиль 480х20х20мм002",
+      "groupGuess": "static-frame",
+      "triangles": 1896,
+      "bboxMm": {
+        "min": [
+          -949,
+          -490,
+          13.499999999999998
+        ],
+        "max": [
+          -929,
+          -10,
+          33.5
+        ]
+      },
+      "sizeMm": [
+        20,
+        480,
+        20
+      ]
+    },
+    {
+      "name": "Link011",
+      "label": "Конструкционный профиль 500х20х20мм007",
+      "groupGuess": "static-frame",
+      "triangles": 1896,
+      "bboxMm": {
+        "min": [
+          -1939,
+          -9.999999999999712,
+          13.499999999999998
+        ],
+        "max": [
+          -1439,
+          10.000000000000398,
+          33.5
+        ]
+      },
+      "sizeMm": [
+        500,
+        20.00000000000011,
+        20
+      ]
+    },
+    {
+      "name": "Link012",
+      "label": "Конструкционный профиль 500х20х20мм008",
+      "groupGuess": "static-frame",
+      "triangles": 1896,
+      "bboxMm": {
+        "min": [
+          -1939,
+          -509.9999999999997,
+          13.499999999999998
+        ],
+        "max": [
+          -1439,
+          -489.9999999999996,
+          33.5
+        ]
+      },
+      "sizeMm": [
+        500,
+        20.000000000000114,
+        20
+      ]
+    },
+    {
+      "name": "Link013",
+      "label": "Конструкционный профиль 480х20х20мм003",
+      "groupGuess": "static-frame",
+      "triangles": 1896,
+      "bboxMm": {
+        "min": [
+          -1944,
+          -490,
+          13.499999999999998
+        ],
+        "max": [
+          -1924,
+          -10,
+          33.5
+        ]
+      },
+      "sizeMm": [
+        20,
+        480,
+        20
+      ]
+    },
+    {
+      "name": "Link014",
+      "label": "3х угловой соединитель002",
+      "groupGuess": "static-frame",
+      "triangles": 2716,
+      "bboxMm": {
+        "min": [
+          -1944,
+          -25.500000000000018,
+          -2.000000000000014
+        ],
+        "max": [
+          -1923.5,
+          9.999999999999996,
+          33.5
+        ]
+      },
+      "sizeMm": [
+        20.5,
+        35.500000000000014,
+        35.500000000000014
+      ]
+    },
+    {
+      "name": "Link015",
+      "label": "3х угловой соединитель003",
+      "groupGuess": "static-frame",
+      "triangles": 2716,
+      "bboxMm": {
+        "min": [
+          -1944,
+          -510,
+          -2.000000000000014
+        ],
+        "max": [
+          -1923.5,
+          -474.5,
+          33.5
+        ]
+      },
+      "sizeMm": [
+        20.5,
+        35.5,
+        35.500000000000014
+      ]
+    },
+    {
+      "name": "Link016",
+      "label": "Роликовый узел в сборе002",
+      "groupGuess": "rollers",
+      "triangles": 42660,
+      "bboxMm": {
+        "min": [
+          -1479.0000000052858,
+          -515,
+          33.449999999999996
+        ],
+        "max": [
+          -1398.9999999947142,
+          35,
+          104.99515666386074
+        ]
+      },
+      "sizeMm": [
+        80.00000001057151,
+        550,
+        71.54515666386075
+      ]
+    },
+    {
+      "name": "Link017",
+      "label": "Роликовый узел в сборе003",
+      "groupGuess": "rollers",
+      "triangles": 42660,
+      "bboxMm": {
+        "min": [
+          -1939.0000000052858,
+          -515,
+          33.449999999999996
+        ],
+        "max": [
+          -1858.9999999947142,
+          35,
+          104.99515666386074
+        ]
+      },
+      "sizeMm": [
+        80.00000001057151,
+        550,
+        71.54515666386075
+      ]
+    },
+    {
+      "name": "Body018",
+      "label": "Лента",
+      "groupGuess": "conveyor-belt",
+      "triangles": 1024,
+      "bboxMm": {
+        "min": [
+          -1924.9919187320213,
+          -500,
+          53.999999999999986
+        ],
+        "max": [
+          46.99191873202125,
+          2.4e-14,
+          106.00000000000011
+        ]
+      },
+      "sizeMm": [
+        1971.9838374640426,
+        500,
+        52.00000000000013
+      ]
+    },
+    {
+      "name": "Body019",
+      "label": "Серво привод",
+      "groupGuess": "pusher-servo",
+      "triangles": 2580,
+      "bboxMm": {
+        "min": [
+          -867.5,
+          -547.9999999999999,
+          110
+        ],
+        "max": [
+          -785.5,
+          -517.9999999999999,
+          165.2
+        ]
+      },
+      "sizeMm": [
+        82,
+        30,
+        55.19999999999999
+      ]
+    },
+    {
+      "name": "Body020",
+      "label": "Держатель-сервопривода",
+      "groupGuess": "pusher-servo",
+      "triangles": 50440,
+      "bboxMm": {
+        "min": [
+          -899.5000000000248,
+          -548,
+          14.999999999999844
+        ],
+        "max": [
+          -753.4999999999839,
+          -510,
+          141.00000000000037
+        ]
+      },
+      "sizeMm": [
+        146.00000000004093,
+        38,
+        126.00000000000053
+      ]
+    },
+    {
+      "name": "Body021",
+      "label": "Держатель серво",
+      "groupGuess": "pusher-servo",
+      "triangles": 9516,
+      "bboxMm": {
+        "min": [
+          -851,
+          -510,
+          33.497873015872926
+        ],
+        "max": [
+          -802,
+          -490,
+          63.497873015872926
+        ]
+      },
+      "sizeMm": [
+        49,
+        20,
+        30
+      ]
+    },
+    {
+      "name": "Link025",
+      "label": "серво001",
+      "groupGuess": "pusher-servo",
+      "triangles": 59956,
+      "bboxMm": {
+        "min": [
+          -1396.5000000000161,
+          -9.999999999999877,
+          14.999999999999844
+        ],
+        "max": [
+          -1250.4999999999752,
+          48.00000000000013,
+          141.00000000000037
+        ]
+      },
+      "sizeMm": [
+        146.00000000004093,
+        58.00000000000001,
+        126.00000000000053
+      ]
+    },
+    {
+      "name": "Link026",
+      "label": "Серво привод001",
+      "groupGuess": "pusher-servo",
+      "triangles": 2580,
+      "bboxMm": {
+        "min": [
+          -1364.5,
+          17.99999999999995,
+          110
+        ],
+        "max": [
+          -1282.5,
+          47.99999999999996,
+          165.2
+        ]
+      },
+      "sizeMm": [
+        82,
+        30.000000000000007,
+        55.19999999999999
+      ]
+    },
+    {
+      "name": "Link027",
+      "label": "Барьер001",
+      "groupGuess": "stop-gate",
+      "triangles": 20062,
+      "bboxMm": {
+        "min": [
+          -1871.1197656323916,
+          -495.1197656323927,
+          117.99999999999983
+        ],
+        "max": [
+          -1333.383347775863,
+          42.75807358037436,
+          218.0000000000001
+        ]
+      },
+      "sizeMm": [
+        537.7364178565285,
+        537.8778392127671,
+        100.00000000000028
+      ]
+    },
+    {
+      "name": "Link028",
+      "label": "Крепление камеры001",
+      "groupGuess": "inspection-frame",
+      "triangles": 84536,
+      "bboxMm": {
+        "min": [
+          -550,
+          -538,
+          13.499999999999993
+        ],
+        "max": [
+          -490,
+          38.000000000000114,
+          533.5
+        ]
+      },
+      "sizeMm": [
+        60,
+        576.0000000000001,
+        520
+      ]
+    },
+    {
+      "name": "Link029",
+      "label": "Барьер002",
+      "groupGuess": "stop-gate",
+      "triangles": 20062,
+      "bboxMm": {
+        "min": [
+          -1374.119765632393,
+          -542.6166522241368,
+          117.99999999999983
+        ],
+        "max": [
+          -836.2419264196258,
+          -4.880234367608182,
+          218.0000000000001
+        ]
+      },
+      "sizeMm": [
+        537.8778392127672,
+        537.7364178565286,
+        100.00000000000028
+      ]
+    }
+  ]
+}
--- a/docs/stage2c_cad_visual/cad-runtime-audit.json
+++ b/docs/stage2c_cad_visual/cad-runtime-audit.json
@@ -0,0 +1,47 @@
+{
+  "glb": "public/models/sorter/conveyor-web.glb",
+  "sizeBytes": 555484,
+  "sha256": "4ccb74e5b92a542cacdb5a322f08c8e23e52c2d582bf8e378be39f40b4c073a8",
+  "nodeCount": 42,
+  "groups": [
+    "motor-and-drive",
+    "rollers",
+    "static-frame",
+    "conveyor-belt",
+    "pusher-servo",
+    "stop-gate",
+    "inspection-frame"
+  ],
+  "motor": {
+    "node": "motor-and-drive/NEMA17",
+    "worldAabbApprox": {
+      "min": [
+        -2.062,
+        0.564,
+        0.212
+      ],
+      "max": [
+        -2.02,
+        0.606,
+        0.284
+      ]
+    },
+    "causeOfDetachedMotor": "procedural StepperMotor at CONVEYOR_END_X — REMOVED in Stage 2C",
+    "cadMotorStatus": "on-frame near belt height Y≈0.585"
+  },
+  "materialsPolicy": {
+    "transparent": false,
+    "opacity": 1,
+    "depthWrite": true,
+    "side": "FrontSide"
+  },
+  "duplicatesRemoved": [
+    "StepperMotor procedural"
+  ],
+  "remainingSpecDerived": [
+    "BeltSection entry/exit extensions",
+    "PusherMechanism junction paddle",
+    "RealSense D435i",
+    "chutes/cages"
+  ]
+}
--- a/docs/stage2c_cad_visual/cad-source-inventory.json
+++ b/docs/stage2c_cad_visual/cad-source-inventory.json
--- a/docs/stage2c_cad_visual/console-errors.json
+++ b/docs/stage2c_cad_visual/console-errors.json
@@ -0,0 +1 @@
+{"defaultRoute":"/?playback=paused","errors":[],"note":"Spot-check via Playwright load; not a full console scrape matrix"}
--- a/docs/stage2c_cad_visual/deployment-report.md
+++ b/docs/stage2c_cad_visual/deployment-report.md
@@ -0,0 +1,17 @@
+# Deployment — Stage 2C
+
+## Local production
+
+- Container `owl-web-1` on `127.0.0.1:3100` hot-updated with Stage 2C `dist/` (asset `index-CA2EvFI-.js`)
+- Preview control: `127.0.0.1:3101` (`vite preview`)
+- Previous container/image retained; no rollback deleted
+
+## Public domain
+
+- `sorter.arhipovdan.ru` remains **BLOCKED_BY_DEPLOYMENT_ACCESS** (external A-record / openresty without this vhost)
+- Required DNS (owner action): A/AAAA or CNAME pointing to the host that terminates TLS for this app and proxies to `127.0.0.1:3100` (or LAN equivalent)
+- Cloudflare tunnel tokens are not published here
+
+## Phone
+
+- NOT_TESTED_ON_REAL_PHONE
--- a/docs/stage2c_cad_visual/drop-validation.json
+++ b/docs/stage2c_cad_visual/drop-validation.json
@@ -0,0 +1,138 @@
+{
+  "generatedAt": "2026-07-30T12:27:01.613Z",
+  "sim": "headless Rapier via simulateDrop (deterministic, dt=1/60, settle 6s)",
+  "runs": 10,
+  "routes": [
+    {
+      "sku": "SKU-001",
+      "route": "box → B",
+      "expectedZone": "B",
+      "runs": 10,
+      "correctLandings": 10,
+      "penetrations": 0,
+      "teleports": 0,
+      "outOfBounds": 0,
+      "frozenInAir": 0,
+      "pusherContacts": "n/a",
+      "sampleFinalPositions": [
+        "(3.00,0.23,-0.00)",
+        "(3.00,0.23,-0.00)",
+        "(3.00,0.23,-0.00)"
+      ],
+      "result": "PASS"
+    },
+    {
+      "sku": "SKU-009",
+      "route": "pen → C",
+      "expectedZone": "C",
+      "runs": 10,
+      "correctLandings": 10,
+      "penetrations": 0,
+      "teleports": 0,
+      "outOfBounds": 0,
+      "frozenInAir": 0,
+      "pusherContacts": 10,
+      "sampleFinalPositions": [
+        "(1.66,0.08,2.32)",
+        "(1.66,0.08,2.32)",
+        "(1.66,0.08,2.32)"
+      ],
+      "result": "PASS"
+    },
+    {
+      "sku": "SKU-005",
+      "route": "pouf → C",
+      "expectedZone": "C",
+      "runs": 10,
+      "correctLandings": 10,
+      "penetrations": 0,
+      "teleports": 0,
+      "outOfBounds": 0,
+      "frozenInAir": 0,
+      "pusherContacts": 10,
+      "sampleFinalPositions": [
+        "(1.96,0.27,1.68)",
+        "(1.96,0.27,1.68)",
+        "(1.96,0.27,1.68)"
+      ],
+      "result": "PASS"
+    },
+    {
+      "sku": "SKU-004",
+      "route": "oversized → C",
+      "expectedZone": "C",
+      "runs": 10,
+      "correctLandings": 10,
+      "penetrations": 0,
+      "teleports": 0,
+      "outOfBounds": 0,
+      "frozenInAir": 0,
+      "pusherContacts": 10,
+      "sampleFinalPositions": [
+        "(1.95,0.30,1.58)",
+        "(1.95,0.30,1.58)",
+        "(1.95,0.30,1.58)"
+      ],
+      "result": "PASS"
+    },
+    {
+      "sku": "SKU-007",
+      "route": "bottle → D",
+      "expectedZone": "D",
+      "runs": 10,
+      "correctLandings": 10,
+      "penetrations": 0,
+      "teleports": 0,
+      "outOfBounds": 0,
+      "frozenInAir": 0,
+      "pusherContacts": 10,
+      "sampleFinalPositions": [
+        "(2.34,0.12,-1.95)",
+        "(2.34,0.12,-1.95)",
+        "(2.34,0.12,-1.95)"
+      ],
+      "result": "PASS"
+    },
+    {
+      "sku": "SKU-006",
+      "route": "plate → D",
+      "expectedZone": "D",
+      "runs": 10,
+      "correctLandings": 10,
+      "penetrations": 0,
+      "teleports": 0,
+      "outOfBounds": 0,
+      "frozenInAir": 0,
+      "pusherContacts": 10,
+      "sampleFinalPositions": [
+        "(1.89,0.09,-1.80)",
+        "(1.89,0.09,-1.80)",
+        "(1.89,0.09,-1.80)"
+      ],
+      "result": "PASS"
+    },
+    {
+      "sku": "SKU-008",
+      "route": "cylinder → D",
+      "expectedZone": "D",
+      "runs": 10,
+      "correctLandings": 10,
+      "penetrations": 0,
+      "teleports": 0,
+      "outOfBounds": 0,
+      "frozenInAir": 0,
+      "pusherContacts": 10,
+      "sampleFinalPositions": [
+        "(2.22,0.10,-2.28)",
+        "(2.22,0.10,-2.28)",
+        "(2.22,0.10,-2.28)"
+      ],
+      "result": "PASS"
+    }
+  ],
+  "summary": {
+    "totalRoutes": 7,
+    "passedRoutes": 7,
+    "result": "PASS"
+  }
+}
--- a/docs/stage2c_cad_visual/materials-audit.json
+++ b/docs/stage2c_cad_visual/materials-audit.json
@@ -0,0 +1,16 @@
+{
+  "slots": [
+    "painted-metal",
+    "brushed-metal",
+    "rubber-belt",
+    "dark-mechanical",
+    "safety-yellow"
+  ],
+  "opaqueForced": true,
+  "transparencyAllowed": [
+    "RealSense glass only (SPEC_DERIVED)",
+    "laser beam debug"
+  ],
+  "surfaceOnlyNodes": [],
+  "note": "FCStd bodies are PartDesign solids; no CAD_SURFACE_ONLY solidify applied"
+}
--- a/docs/stage2c_cad_visual/mechanism-cad-map.md
+++ b/docs/stage2c_cad_visual/mechanism-cad-map.md
@@ -0,0 +1,23 @@
+# Mechanism CAD Map — Stage 2C
+
+## Author CAD nodes (conveer.FCStd → conveyor-web.glb)
+
+| Group | Nodes (labels) | Role | Usable as junction paddle? |
+|---|---|---|---|
+| stop-gate | Барьер001, Барьер002 | Metering barriers on CAD module (~x CAD −0.8…−1.8 m) | No — wrong location/stroke for B/C/D junction |
+| pusher-servo | Серво привод, Держатель-сервопривода, серво001, … | Side-mounted servo + holder on CAD module | Partial — REAL_CAD visual; no proven junction kinematics |
+| motor-and-drive | NEMA17, шкивы, ремень | Drive at CAD module | Yes (drive only) |
+
+## Junction sorting (x≈1.5 m, outside CAD module span)
+
+CAD module world span X ≈ [−2.086, −0.076]. Domain junction / paddles live at x≈1.5 → **outside** author CAD solids.
+
+**Decision:** keep `PusherMechanism` (SPEC_DERIVED angled paddle) as default kinematic contact body.
+**CAD_MECHANISM_UNUSABLE** for junction paddle: no author solid at junction with matching stroke/face.
+
+CAD `pusher-servo/*` remains visible as REAL_CAD static geometry on the metering module (not hidden).
+
+## Contact events (runtime)
+
+mechanismArmed → contactStarted → peakContactForce → contactEnded → physicsReleased → receiverEntered → itemSettled
+(asserted in headless via pusher contact + receiver volumes; see drop-validation.json)
--- a/docs/stage2c_cad_visual/performance-cad-corrected.json
+++ b/docs/stage2c_cad_visual/performance-cad-corrected.json
@@ -0,0 +1 @@
+{"profile":"B-cad-assembly","note":"No full 30s×3 GPU profile in this session; SwiftShader excluded","status":"NOT_REMEASURED","layoutCanvasHeightRatio":1.0}
--- a/docs/stage2c_cad_visual/performance-cad-physics.json
+++ b/docs/stage2c_cad_visual/performance-cad-physics.json
@@ -0,0 +1 @@
+{"profile":"C-cad-physics","status":"NOT_REMEASURED","physicsTimestep":0.0166667,"runtimeHeadlessHashEqual":true}
--- a/docs/stage2c_cad_visual/performance-control.json
+++ b/docs/stage2c_cad_visual/performance-control.json
@@ -0,0 +1 @@
+{"profile":"A-stage2-control","note":"Baseline Stage 2B not re-profiled in Stage 2C session","status":"NOT_REMEASURED"}
--- a/docs/stage2c_cad_visual/performance-final.json
+++ b/docs/stage2c_cad_visual/performance-final.json
@@ -0,0 +1 @@
+{"profile":"D-final","status":"PARTIAL","budget":{"avgFpsMin":45,"p95MsMax":28,"drawCallsMax":250,"trisMax":500000},"measured":null,"note":"Formal multi-run GPU profile deferred; unit/e2e/build green"}
--- a/docs/stage2c_cad_visual/runtime-headless-config-hash.json
+++ b/docs/stage2c_cad_visual/runtime-headless-config-hash.json
@@ -0,0 +1,55 @@
+{
+  "generatedAt": "2026-07-30T12:27:15.737Z",
+  "runtimeHash": "7ee15ad3e879a44a",
+  "headlessHash": "7ee15ad3e879a44a",
+  "equal": true,
+  "timestepEqual": true,
+  "timestepSec": 0.016666666666666666,
+  "snapshot": {
+    "timestep": 0.016666666666666666,
+    "gravity": [
+      0,
+      -9.81,
+      0
+    ],
+    "pusherHalfExtents": [
+      0.5,
+      0.14,
+      0.025
+    ],
+    "pusherCenterY": 0.842,
+    "pusherEngage": {
+      "x": 1.5,
+      "z": 0
+    },
+    "staticColliderCount": 25,
+    "staticColliderIds": [
+      "world-floor",
+      "belt-slab",
+      "b-spur",
+      "chute-C-floor",
+      "chute-C-rail-left",
+      "chute-C-rail-right",
+      "chute-D-floor",
+      "chute-D-rail-left",
+      "chute-D-rail-right",
+      "b-bin-floor",
+      "b-bin-wall-z+",
+      "b-bin-wall-z-",
+      "b-bin-wall-x+",
+      "b-bin-entry-lip",
+      "b-drop-chute",
+      "cage-C-floor",
+      "cage-C-wall-x-",
+      "cage-C-wall-x+",
+      "cage-C-wall-back",
+      "cage-C-entry-sill",
+      "cage-D-floor",
+      "cage-D-wall-x-",
+      "cage-D-wall-x+",
+      "cage-D-wall-back",
+      "cage-D-entry-sill"
+    ],
+    "staticColliderFingerprint": "world-floor|8.00000,0.05000,6.00000|0.00000,-0.05000,0.00000|0.00000,0.00000,0.00000|0.8000;belt-slab|3.17500,0.01200,0.25000|-1.02500,0.68600,0.00000|0.00000,0.00000,0.00000|0.7000;b-spur|0.32500,0.02000,0.22000|1.82500,0.67800,0.00000|0.00000,0.00000,0.00000|0.4000;chute-C-floor|0.50000,0.01000,0.72981|1.70000,0.39000,0.92000|0.37160,0.00000,0.00000|0.2000;chute-C-rail-left|0.01000,0.03500,0.72981|1.19000,0.43500,0.92000|0.37160,0.00000,0.00000|0.3000;chute-C-rail-right|0.01000,0.03500,0.72981|2.21000,0.43500,0.92000|0.37160,0.00000,0.00000|0.3000;chute-D-floor|0.50000,0.01000,0.72981|1.70000,0.39000,-0.92000|-0.37160,0.00000,0.00000|0.2000;chute-D-rail-left|0.01000,0.03500,0.72981|1.19000,0.43500,-0.92000|-0.37160,0.00000,0.00000|0.3000;chute-D-rail-right|0.01000,0.03500,0.72981|2.21000,0.43500,-0.92000|-0.37160,0.00000,0.00000|0.3000;b-bin-floor|0.60000,0.02000,0.40000|3.35000,0.06000,0.00000|0.00000,0.00000,0.00000|0.8000;b-bin-wall-z+|0.60000,0.25000,0.01500|3.35000,0.33000,0.40000|0.00000,0.00000,0.00000|0.6000;b-bin-wall-z-|0.60000,0.25000,0.01500|3.35000,0.33000,-0.40000|0.00000,0.00000,0.00000|0.6000;b-bin-wall-x+|0.01500,0.25000,0.40000|3.95000,0.33000,0.00000|0.00000,0.00000,0.00000|0.6000;b-bin-entry-lip|0.01500,0.04000,0.40000|2.75000,0.12000,0.00000|0.00000,0.00000,0.00000|0.6000;b-drop-chute|0.46755,0.00800,0.21000|2.50000,0.39500,0.00000|0.00000,0.00000,-0.68339|0.2500;cage-C-floor|0.60000,0.04000,0.40000|2.00000,0.04000,2.00000|0.00000,0.00000,0.00000|0.8000;cage-C-wall-x-|0.02000,0.40000,0.40000|1.40000,0.40000,2.00000|0.00000,0.00000,0.00000|0.5000;cage-C-wall-x+|0.02000,0.40000,0.40000|2.60000,0.40000,2.00000|0.00000,0.00000,0.00000|0.5000;cage-C-wall-back|0.60000,0.40000,0.02000|2.00000,0.40000,2.40000|0.00000,0.00000,0.00000|0.5000;cage-C-entry-sill|0.60000,0.02000,0.01500|2.00000,0.10000,1.60000|0.00000,0.00000,0.00000|0.5000;cage-D-floor|0.60000,0.04000,0.40000|2.00000,0.04000,-2.00000|0.00000,0.00000,0.00000|0.8000;cage-D-wall-x-|0.02000,0.40000,0.40000|1.40000,0.40000,-2.00000|0.00000,0.00000,0.00000|0.5000;cage-D-wall-x+|0.02000,0.40000,0.40000|2.60000,0.40000,-2.00000|0.00000,0.00000,0.00000|0.5000;cage-D-wall-back|0.60000,0.40000,0.02000|2.00000,0.40000,-2.40000|0.00000,0.00000,0.00000|0.5000;cage-D-entry-sill|0.60000,0.02000,0.01500|2.00000,0.10000,-1.60000|0.00000,0.00000,0.00000|0.5000"
+  }
+}
--- a/docs/stage2c_cad_visual/screenshots/01-current-before.png
+++ b/docs/stage2c_cad_visual/screenshots/01-current-before.png
--- a/docs/stage2c_cad_visual/screenshots/02-cad-contact-sheet.png
+++ b/docs/stage2c_cad_visual/screenshots/02-cad-contact-sheet.png
--- a/docs/stage2c_cad_visual/screenshots/03-single-conveyor-overview.png
+++ b/docs/stage2c_cad_visual/screenshots/03-single-conveyor-overview.png
--- a/docs/stage2c_cad_visual/screenshots/04-motor-correct-position.png
+++ b/docs/stage2c_cad_visual/screenshots/04-motor-correct-position.png
--- a/docs/stage2c_cad_visual/screenshots/05-volumetric-rollers.png
+++ b/docs/stage2c_cad_visual/screenshots/05-volumetric-rollers.png
--- a/docs/stage2c_cad_visual/screenshots/06-volumetric-brackets.png
+++ b/docs/stage2c_cad_visual/screenshots/06-volumetric-brackets.png
--- a/docs/stage2c_cad_visual/screenshots/07-real-sorter-mechanism.png
+++ b/docs/stage2c_cad_visual/screenshots/07-real-sorter-mechanism.png
--- a/docs/stage2c_cad_visual/screenshots/08-mechanism-contact.png
+++ b/docs/stage2c_cad_visual/screenshots/08-mechanism-contact.png
--- a/docs/stage2c_cad_visual/screenshots/09-no-measurement-panel.png
+++ b/docs/stage2c_cad_visual/screenshots/09-no-measurement-panel.png
--- a/docs/stage2c_cad_visual/screenshots/10-full-height-layout.png
+++ b/docs/stage2c_cad_visual/screenshots/10-full-height-layout.png
--- a/docs/stage2c_cad_visual/screenshots/11-box-scale.png
+++ b/docs/stage2c_cad_visual/screenshots/11-box-scale.png
--- a/docs/stage2c_cad_visual/screenshots/12-bottle-scale.png
+++ b/docs/stage2c_cad_visual/screenshots/12-bottle-scale.png
--- a/docs/stage2c_cad_visual/screenshots/13-plate-scale.png
+++ b/docs/stage2c_cad_visual/screenshots/13-plate-scale.png
--- a/docs/stage2c_cad_visual/screenshots/14-pen-close-up.png
+++ b/docs/stage2c_cad_visual/screenshots/14-pen-close-up.png
--- a/docs/stage2c_cad_visual/screenshots/15-route-b-final.png
+++ b/docs/stage2c_cad_visual/screenshots/15-route-b-final.png
--- a/docs/stage2c_cad_visual/screenshots/16-route-c-final.png
+++ b/docs/stage2c_cad_visual/screenshots/16-route-c-final.png
--- a/docs/stage2c_cad_visual/screenshots/17-route-d-final.png
+++ b/docs/stage2c_cad_visual/screenshots/17-route-d-final.png
--- a/docs/stage2c_cad_visual/screenshots/18-mobile-svg.png
+++ b/docs/stage2c_cad_visual/screenshots/18-mobile-svg.png
--- a/docs/stage2c_cad_visual/screenshots/cad-contact-sheet.png
+++ b/docs/stage2c_cad_visual/screenshots/cad-contact-sheet.png
--- a/docs/stage2c_cad_visual/videos/README.md
+++ b/docs/stage2c_cad_visual/videos/README.md
@@ -0,0 +1,16 @@
+# Stage 2C runtime videos
+
+Recorded WebM files are **not** shipped in this drop.
+
+Evidence used instead:
+- Headless drop validation `7/7 × 10/10` (`drop-validation.json`) with pusher contact asserts
+- Runtime/headless config hash equality (`runtime-headless-config-hash.json`)
+- Still screenshots `07-real-sorter-mechanism.png`, `08-mechanism-contact.png`, route finals
+
+To capture locally (preview on :3101):
+
+```bash
+# example: use browser MediaRecorder or ffmpeg x11grab against the preview window
+```
+
+Do not treat this README as a substitute for visual PASS of contact trajectories.
--- a/docs/stage2c_cad_visual/visual-physics-review.md
+++ b/docs/stage2c_cad_visual/visual-physics-review.md
@@ -0,0 +1,27 @@
+# Visual Physics Review — Stage 2C
+
+## Layout
+
+- Canvas heightRatio = 1.0, emptyRatio = 0 (Playwright + CDP)
+- White MEASUREMENT (`CVInspectionOverlay`) unmounted on `/`
+- Compact HUD (ITEM/STATUS/CATEGORY) retained top-right (allowed)
+
+## Motor
+
+- Cause of detached motor: procedural `StepperMotor` at CONVEYOR_END_X — **removed**
+- CAD NEMA17 world AABB ≈ Y 0.56–0.61 (on frame under belt drive) — not floor-hidden
+
+## Mechanism
+
+- Junction paddle: SPEC_DERIVED (CAD lacks junction paddle solid)
+- Contact-based C/D handoff unchanged; headless 7/7×10/10 with pusher contact
+
+## Parity
+
+- runtimeHash == headlessHash: 7ee15ad3e879a44a
+
+## Remaining visual debt
+
+- Entry/exit belt still SPEC_DERIVED (modular, not scaled CAD)
+- CAD belt segment looks brighter/different from extensions
+- Runtime WebM trajectories not recorded in this drop
--- a/e2e/stage2c-layout.spec.ts
+++ b/e2e/stage2c-layout.spec.ts
@@ -0,0 +1,49 @@
+import { test, expect } from '@playwright/test';
+
+test.setTimeout(90_000);
+
+test.describe('Stage 2C layout + measurement panel', () => {
+  test('default / has no Measurement panel and canvas fills viewport height', async ({ page }) => {
+    await page.goto('/?playback=paused');
+    await expect(page.locator('canvas')).toBeVisible({ timeout: 60_000 });
+    await page.waitForFunction(() => !document.body.innerText.includes('Loading 3D'), {
+      timeout: 60_000,
+    });
+    await page.waitForTimeout(500);
+
+    await expect(page.locator('.cv-overlay')).toHaveCount(0);
+    await expect(page.getByTestId('measurement-compact')).toHaveCount(0);
+
+    const metrics = await page.evaluate(() => {
+      const vh = window.innerHeight;
+      const canvas = document.querySelector('canvas');
+      const svg = document.querySelector('[data-testid="main-svg-fallback"]');
+      const scene = canvas ?? svg;
+      if (!scene) return { ok: false as const, reason: 'no scene' };
+      const r = scene.getBoundingClientRect();
+      const heightRatio = r.height / vh;
+      const emptyBelow = Math.max(0, vh - (r.top + r.height));
+      const emptyRatio = emptyBelow / vh;
+      return {
+        ok: true as const,
+        heightRatio,
+        emptyRatio,
+        sceneTop: r.top,
+        sceneHeight: r.height,
+        vh,
+      };
+    });
+
+    expect(metrics.ok).toBe(true);
+    if (!metrics.ok) return;
+    expect(metrics.heightRatio).toBeGreaterThanOrEqual(0.85);
+    expect(metrics.emptyRatio).toBeLessThanOrEqual(0.2);
+  });
+
+  test('full Measurement panel only with debug=1&measurement=full', async ({ page }) => {
+    await page.setViewportSize({ width: 1280, height: 800 });
+    await page.goto('/?debug=1&playback=paused');
+    await expect(page.locator('canvas')).toBeVisible({ timeout: 60_000 });
+    await expect(page.locator('.cv-overlay:not(.cv-overlay-compact)')).toHaveCount(0);
+  });
+});
--- a/src/components/ThreeD/ConveyorCadModel.tsx
+++ b/src/components/ThreeD/ConveyorCadModel.tsx
@@ -35,7 +35,16 @@ function materialFor(slot: string): THREE.MeshStandardMaterial {
      'dark-mechanical': { color: '#3a4148', metalness: 0.6, roughness: 0.5 },
      'safety-yellow': { color: '#f5b301', metalness: 0.2, roughness: 0.55 },
    };
-    MATERIALS[slot] = new THREE.MeshStandardMaterial(defs[slot] ?? defs['painted-metal']);
+    const def = defs[slot] ?? defs['painted-metal'];
+    // Stage 2C §9.1 — opaque machine metals: no accidental alpha / DoubleSide bleed.
+    MATERIALS[slot] = new THREE.MeshStandardMaterial({
+      ...def,
+      transparent: false,
+      opacity: 1,
+      depthWrite: true,
+      depthTest: true,
+      side: THREE.FrontSide,
+    });
  }
  return MATERIALS[slot];
 }
@@ -102,6 +111,11 @@ export function ConveyorCadModel({
      mesh.material = materialFor(slotFor(name));
      mesh.castShadow = shadows;
      mesh.receiveShadow = shadows;
+      // Force opaque even if a future GLB embeds transparent materials.
+      const mat = mesh.material as THREE.MeshStandardMaterial;
+      mat.transparent = false;
+      mat.opacity = 1;
+      mat.depthWrite = true;
      if (name.startsWith('stop-gate/') || name.startsWith('rollers/Ролик') || name.startsWith('rollers/Вал')) {
        toPivot.push(mesh);
      }
--- a/src/components/ThreeD/SorterDigitalTwinContinuous.tsx
+++ b/src/components/ThreeD/SorterDigitalTwinContinuous.tsx
@@ -42,14 +42,9 @@ import {
  BELT_TOP_Y,
  BELT_THICKNESS_M,
  CONVEYOR_WIDTH_M,
-  ROLLER_RADIUS_M,
-  ROLLER_SPACING_M,
  FRAME_HEIGHT_M,
  SIDE_GUARD_HEIGHT_M,
  LEG_WIDTH_M,
-  MOTOR_WIDTH_M,
-  MOTOR_HEIGHT_M,
-  MOTOR_DEPTH_M,
  DRIVE_ROLLER_RADIUS_M,
  ZONES,
  CAMERA_RIG,
@@ -61,6 +56,11 @@ import {
  CAGE_FLOOR_Y,
  CONVEYOR_SPEED_MPS,
 } from '../../domain/physicalLayout';
+import {
+  CAD_ROLLER_PITCH_M,
+  CAD_ROLLER_RADIUS_M,
+  CAD_SUPPORT_SPACING_M,
+} from '../../domain/cadAssemblyParams';
 import { CHUTE_PITCH, CHUTE_LENGTH, CHUTE_MID_Y, CHUTE_MID_Z, CHUTE_X, CHUTE_HALF_W } from '../../domain/physicsWorldLayout';
 import PerfCollector from './PerfCollector';
 import PerfOverlay from './PerfOverlay';
@@ -133,8 +133,8 @@ function getItemMaterial(itemId: string) {
 // Physical layout constants
 const BELT_Y = BELT_TOP_Y;                    // 0.7m - top of belt where items ride
 const BELT_UNDERSIDE_Y = BELT_TOP_Y - BELT_THICKNESS_M; // 0.685m
-const ROLLER_Y = BELT_UNDERSIDE_Y - ROLLER_RADIUS_M;    // ~0.645m - roller center
-const FRAME_TOP_Y = ROLLER_Y - ROLLER_RADIUS_M - 0.02;  // Top of frame structure
+const ROLLER_Y = BELT_UNDERSIDE_Y - CAD_ROLLER_RADIUS_M;
+const FRAME_TOP_Y = ROLLER_Y - CAD_ROLLER_RADIUS_M - 0.02;
 const CONVEYOR_START_X = -4.2;
 const CONVEYOR_END_X = B_RECEIVER.transferEndX + 0.15; // main belt ends at short B spur tip
 /** Max items rendered simultaneously (perf cap). */
@@ -267,12 +267,19 @@ function MotionTrail({
  );
 }

-/** Static roller cylinder — no per-frame rotation (belt stripes show movement). */
+/** Static roller — CAD pitch/radius for modular extensions (no non-uniform scale of CAD module). */
 function StaticRoller({ position }: { position: [number, number, number] }) {
  return (
    <mesh position={position} rotation={[0, 0, Math.PI / 2]}>
-      <cylinderGeometry args={[ROLLER_RADIUS_M, ROLLER_RADIUS_M, CONVEYOR_WIDTH_M - 0.02, 8]} />
-      <meshStandardMaterial color={COLORS.rollers} metalness={0.4} roughness={0.5} />
+      <cylinderGeometry args={[CAD_ROLLER_RADIUS_M, CAD_ROLLER_RADIUS_M, CONVEYOR_WIDTH_M - 0.02, 16]} />
+      <meshStandardMaterial
+        color={COLORS.rollers}
+        metalness={0.85}
+        roughness={0.32}
+        transparent={false}
+        opacity={1}
+        depthWrite
+      />
    </mesh>
  );
 }
@@ -302,56 +309,7 @@ function BeltStripe({ baseOffset, elapsedMs }: { baseOffset: number; elapsedMs:
  );
 }

-/** Stepper motor drive unit with pulse indicator */
-function StepperMotor({ position, pulseActive }: { position: [number, number, number]; pulseActive: boolean }) {
-  const pulseRef = useRef<Mesh>(null);
-  const rotationRef = useRef(0);
-  
-  useFrame((_, delta) => {
-    if (pulseRef.current && pulseActive) {
-      rotationRef.current += delta * 8;
-      pulseRef.current.rotation.z = rotationRef.current;
-    }
-  });
-  
-  return (
-    <group position={position}>
-      {/* Motor body */}
-      <mesh position={[0, 0, CONVEYOR_WIDTH_M / 2 + MOTOR_DEPTH_M / 2 + 0.02]}>
-        <boxGeometry args={[MOTOR_WIDTH_M, MOTOR_HEIGHT_M, MOTOR_DEPTH_M]} />
-        <meshStandardMaterial color="#475569" metalness={0.6} roughness={0.3} />
-      </mesh>
-      {/* Motor shaft - rotates when active */}
-      <mesh 
-        ref={pulseRef}
-        position={[0, 0, CONVEYOR_WIDTH_M / 2 + 0.01]} 
-        rotation={[Math.PI / 2, 0, 0]}
-      >
-        <cylinderGeometry args={[0.015, 0.015, 0.03, 8]} />
-        <meshStandardMaterial color="#94a3b8" metalness={0.7} roughness={0.2} />
-      </mesh>
-      {/* Drive pulley */}
-      <mesh position={[0, 0, CONVEYOR_WIDTH_M / 2 - 0.02]} rotation={[Math.PI / 2, 0, 0]}>
-        <cylinderGeometry args={[0.035, 0.035, 0.025, 12]} />
-        <meshStandardMaterial color="#64748b" metalness={0.5} roughness={0.4} />
-      </mesh>
-      {/* Belt to drive roller */}
-      <mesh position={[0, DRIVE_ROLLER_RADIUS_M / 2, CONVEYOR_WIDTH_M / 2 - 0.02]}>
-        <boxGeometry args={[0.01, DRIVE_ROLLER_RADIUS_M + 0.02, 0.015]} />
-        <meshStandardMaterial color="#1e293b" />
-      </mesh>
-      {/* Pulse indicator LED */}
-      <mesh position={[0, MOTOR_HEIGHT_M / 2 - 0.01, CONVEYOR_WIDTH_M / 2 + MOTOR_DEPTH_M + 0.025]}>
-        <sphereGeometry args={[0.008, 8, 8]} />
-        <meshStandardMaterial 
-          color={pulseActive ? '#22d3ee' : '#475569'}
-          emissive={pulseActive ? '#22d3ee' : '#000'}
-          emissiveIntensity={pulseActive ? 0.8 : 0}
-        />
-      </mesh>
-    </group>
-  );
-}
+/** StepperMotor removed in Stage 2C — CAD motor-and-drive/NEMA17 is the sole drive unit. */

 /** Laser beam from rangefinder to item — static opacity, no useFrame. */
 function LaserBeam({ active, itemY }: { active: boolean; itemY: number }) {
@@ -467,26 +425,27 @@ function SupportLeg({ x }: { x: number }) {
 * Belt top surface at 0.7m (BELT_TOP_Y)
 */
 /**
- * Belt extension segment (SPEC_DERIVED) — entry/exit sections flanking the
- * CAD conveyor module. Same 500 mm width / 700 mm belt top as the real unit.
+ * Belt extension segment (SPEC_DERIVED modular) — entry/exit flanking the CAD
+ * module. Uses CAD roller pitch (500 mm) and radius (25 mm); never scales the GLB.
 */
 function BeltSection({ startX, endX, simplified, shadows }: { startX: number; endX: number; simplified: boolean; shadows: boolean }) {
-  const spacing = simplified ? ROLLER_SPACING_M * 2 : ROLLER_SPACING_M;
+  const spacing = simplified ? CAD_ROLLER_PITCH_M * 2 : CAD_ROLLER_PITCH_M;
  const length = endX - startX;
  const centerX = (startX + endX) / 2;
  const rollerCount = Math.max(1, Math.floor(length / spacing));
+  const rollerY = BELT_Y - BELT_THICKNESS_M - CAD_ROLLER_RADIUS_M - 0.01;

  const rollerPositions = useMemo(() => {
    const positions: [number, number, number][] = [];
    for (let i = 0; i < rollerCount; i++) {
-      positions.push([startX + spacing / 2 + i * spacing, ROLLER_Y, 0]);
+      positions.push([startX + spacing / 2 + i * spacing, rollerY, 0]);
    }
    return positions;
-  }, [rollerCount, spacing, startX]);
+  }, [rollerCount, spacing, startX, rollerY]);

  const legPositions = useMemo(() => {
    const positions: number[] = [];
-    for (let x = startX + 0.5; x < endX - 0.3; x += 2.0) {
+    for (let x = startX + 0.5; x < endX - 0.3; x += CAD_SUPPORT_SPACING_M) {
      positions.push(x);
    }
    return positions;
@@ -496,23 +455,23 @@ function BeltSection({ startX, endX, simplified, shadows }: { startX: number; en
    <group>
      <mesh position={[centerX, BELT_Y - BELT_THICKNESS_M / 2, 0]} receiveShadow={shadows}>
        <boxGeometry args={[length, BELT_THICKNESS_M, CONVEYOR_WIDTH_M]} />
-        <meshStandardMaterial color={COLORS.belt} roughness={0.85} metalness={0.05} />
+        <meshStandardMaterial color={COLORS.belt} roughness={0.85} metalness={0.05} transparent={false} opacity={1} depthWrite />
      </mesh>
      <mesh position={[centerX, BELT_Y + SIDE_GUARD_HEIGHT_M / 2, CONVEYOR_WIDTH_M / 2 + 0.02]}>
        <boxGeometry args={[length, SIDE_GUARD_HEIGHT_M, 0.025]} />
-        <meshStandardMaterial color={COLORS.sideGuards} metalness={0.4} roughness={0.5} />
+        <meshStandardMaterial color={COLORS.sideGuards} metalness={0.55} roughness={0.45} transparent={false} opacity={1} depthWrite />
      </mesh>
      <mesh position={[centerX, BELT_Y + SIDE_GUARD_HEIGHT_M / 2, -CONVEYOR_WIDTH_M / 2 - 0.02]}>
        <boxGeometry args={[length, SIDE_GUARD_HEIGHT_M, 0.025]} />
-        <meshStandardMaterial color={COLORS.sideGuards} metalness={0.4} roughness={0.5} />
+        <meshStandardMaterial color={COLORS.sideGuards} metalness={0.55} roughness={0.45} transparent={false} opacity={1} depthWrite />
      </mesh>
      <mesh position={[centerX, FRAME_TOP_Y + 0.025, CONVEYOR_WIDTH_M / 2 + 0.01]} castShadow={shadows}>
        <boxGeometry args={[length, 0.05, 0.04]} />
-        <meshStandardMaterial color={COLORS.conveyorFrame} metalness={0.5} roughness={0.4} />
+        <meshStandardMaterial color={COLORS.conveyorFrame} metalness={0.55} roughness={0.4} transparent={false} opacity={1} depthWrite />
      </mesh>
      <mesh position={[centerX, FRAME_TOP_Y + 0.025, -CONVEYOR_WIDTH_M / 2 - 0.01]} castShadow={shadows}>
        <boxGeometry args={[length, 0.05, 0.04]} />
-        <meshStandardMaterial color={COLORS.conveyorFrame} metalness={0.5} roughness={0.4} />
+        <meshStandardMaterial color={COLORS.conveyorFrame} metalness={0.55} roughness={0.4} transparent={false} opacity={1} depthWrite />
      </mesh>
      {rollerPositions.map((pos, i) => (
        <StaticRoller key={i} position={pos} />
@@ -525,17 +484,16 @@ function BeltSection({ startX, endX, simplified, shadows }: { startX: number; en
 }

 /**
- * Conveyor: CAD module (REAL_CAD) + entry/exit belt extensions (SPEC_DERIVED).
- * Gate/roller/belt motion is driven by the domain visual-state adapter.
+ * SorterCadAssembly (inline): sole conveyor geometry source —
+ * REAL_CAD module + modular SPEC_DERIVED entry/exit at CAD pitch.
+ * No procedural motor (CAD NEMA17 only).
 */
-function ConveyorBelt({ pulseActive, elapsedMs, simplified, shadows = false, gateOpen = false, beltVelocityMps = 0, rollerOmega = 0 }: { pulseActive: boolean; elapsedMs: number; simplified: boolean; shadows?: boolean; gateOpen?: boolean; beltVelocityMps?: number; rollerOmega?: number }) {
+function ConveyorBelt({ pulseActive: _pulseActive, elapsedMs, simplified, shadows = false, gateOpen = false, beltVelocityMps = 0, rollerOmega = 0 }: { pulseActive: boolean; elapsedMs: number; simplified: boolean; shadows?: boolean; gateOpen?: boolean; beltVelocityMps?: number; rollerOmega?: number }) {
  const stripeOffsets = simplified ? [-2, 0, 2] : [-3, -1, 0.5, 2];
  const [cadStart, cadEnd] = CONVEYOR_CAD_SPAN_X;

  return (
-    <group>
-      {/* CAD-derived conveyor module (real machine: frame, belt, rollers,
-          drive, metering gates, servo diverters, camera arch) */}
+    <group name="SorterCadAssembly" userData={{ role: 'single-cad-conveyor' }}>
      <Suspense fallback={null}>
        <ConveyorCadModel
          gateOpen={gateOpen}
@@ -545,39 +503,30 @@ function ConveyorBelt({ pulseActive, elapsedMs, simplified, shadows = false, gat
        />
      </Suspense>

-      {/* Entry extension: zone A feed into the CAD module */}
      <BeltSection startX={CONVEYOR_START_X} endX={cadStart} simplified={simplified} shadows={shadows} />
-      {/* Exit extension: CAD module discharge to the B spur */}
      <BeltSection startX={cadEnd} endX={CONVEYOR_END_X} simplified={simplified} shadows={shadows} />

-      {/* Belt stripes — deterministic movement synced to item (offset = time * 1 m/s) */}
      {stripeOffsets.map((offset, i) => (
        <BeltStripe key={i} baseOffset={offset} elapsedMs={elapsedMs} />
      ))}

-      {/* Drive roller at end (larger) */}
-      <mesh position={[CONVEYOR_END_X - 0.1, ROLLER_Y, 0]} rotation={[0, 0, Math.PI / 2]}>
+      <mesh position={[CONVEYOR_END_X - 0.1, BELT_Y - BELT_THICKNESS_M - CAD_ROLLER_RADIUS_M - 0.01, 0]} rotation={[0, 0, Math.PI / 2]}>
        <cylinderGeometry args={[DRIVE_ROLLER_RADIUS_M, DRIVE_ROLLER_RADIUS_M, CONVEYOR_WIDTH_M - 0.02, 16]} />
-        <meshStandardMaterial color="#64748b" metalness={0.5} roughness={0.4} />
+        <meshStandardMaterial color="#64748b" metalness={0.5} roughness={0.4} transparent={false} opacity={1} depthWrite />
      </mesh>

-      {/* Tension roller at start (larger) */}
-      <mesh position={[CONVEYOR_START_X + 0.1, ROLLER_Y, 0]} rotation={[0, 0, Math.PI / 2]}>
+      <mesh position={[CONVEYOR_START_X + 0.1, BELT_Y - BELT_THICKNESS_M - CAD_ROLLER_RADIUS_M - 0.01, 0]} rotation={[0, 0, Math.PI / 2]}>
        <cylinderGeometry args={[DRIVE_ROLLER_RADIUS_M * 0.9, DRIVE_ROLLER_RADIUS_M * 0.9, CONVEYOR_WIDTH_M - 0.02, 16]} />
-        <meshStandardMaterial color="#64748b" metalness={0.5} roughness={0.4} />
+        <meshStandardMaterial color="#64748b" metalness={0.5} roughness={0.4} transparent={false} opacity={1} depthWrite />
      </mesh>

-      {/* Stepper motor at drive end */}
-      <StepperMotor position={[CONVEYOR_END_X - 0.1, ROLLER_Y, 0]} pulseActive={pulseActive} />
-
-      {/* End caps / guards */}
      <mesh position={[CONVEYOR_START_X, BELT_Y - 0.05, 0]}>
        <boxGeometry args={[0.05, 0.12, CONVEYOR_WIDTH_M + 0.1]} />
-        <meshStandardMaterial color={COLORS.conveyorFrame} />
+        <meshStandardMaterial color={COLORS.conveyorFrame} transparent={false} opacity={1} depthWrite />
      </mesh>
      <mesh position={[CONVEYOR_END_X, BELT_Y - 0.05, 0]}>
        <boxGeometry args={[0.05, 0.12, CONVEYOR_WIDTH_M + 0.1]} />
-        <meshStandardMaterial color={COLORS.conveyorFrame} />
+        <meshStandardMaterial color={COLORS.conveyorFrame} transparent={false} opacity={1} depthWrite />
      </mesh>
    </group>
  );
--- a/src/components/ThreeD/SorterPhysics.tsx
+++ b/src/components/ThreeD/SorterPhysics.tsx
@@ -17,8 +17,9 @@ import { useRef, type ReactNode } from 'react';
 import { useFrame } from '@react-three/fiber';
 import { Physics, RigidBody, CuboidCollider, useRapier } from '@react-three/rapier';
 import { getStaticColliders } from '../../domain/physicsWorldLayout';
+import { PHYSICS_TIMESTEP_SEC } from '../../domain/physicsTimestep';

-export const PHYSICS_DT = 1 / 60;
+export const PHYSICS_DT = PHYSICS_TIMESTEP_SEC;
 const MAX_SUBSTEPS = 4;

 /**
--- a/src/domain/cadAssemblyParams.ts
+++ b/src/domain/cadAssemblyParams.ts
@@ -0,0 +1,45 @@
+/**
+ * Stage 2C — modular CAD conveyor assembly parameters.
+ *
+ * Derived from 3d_models/conveer.FCStd (manifest Body and Link bbox mm) and
+ * OZON Track 3 layout (500 mm belt / 700 mm height). Extensions flanking the
+ * ~2.01 m CAD module use the same pitch/width/height — never non-uniform scale.
+ */
+
+/** Author CAD module length after bake+placement (m). */
+export const CAD_MODULE_LENGTH_M = 2.01;
+/** CAD roller assembly pitch along the line (profiles / Link005 spacing ~500 mm). */
+export const CAD_ROLLER_PITCH_M = 0.5;
+/** CAD roller outer radius — Body002 roller diameter 50 mm. */
+export const CAD_ROLLER_RADIUS_M = 0.025;
+/** Spec / CAD belt width. */
+export const CAD_CONVEYOR_WIDTH_M = 0.5;
+/** Belt top height from floor. */
+export const CAD_BELT_HEIGHT_M = 0.7;
+/** Support leg spacing along extensions. */
+export const CAD_SUPPORT_SPACING_M = 2.0;
+/** Full domain line length (entry A to B spur tip), meters. */
+export const CAD_TOTAL_LINE_LENGTH_M = 8.5;
+
+export const CAD_ASSEMBLY_PARAMS = {
+  segmentLength: CAD_MODULE_LENGTH_M,
+  rollerPitch: CAD_ROLLER_PITCH_M,
+  rollerRadius: CAD_ROLLER_RADIUS_M,
+  conveyorWidth: CAD_CONVEYOR_WIDTH_M,
+  beltHeight: CAD_BELT_HEIGHT_M,
+  supportSpacing: CAD_SUPPORT_SPACING_M,
+  totalLineLength: CAD_TOTAL_LINE_LENGTH_M,
+} as const;
+
+/** Structured correction transforms (bake is authoritative; JSX must not invent offsets). */
+export const CAD_TRANSFORM_MANIFEST = {
+  bakeFormula: '(x,y,z)_mm_Zup -> (-x, z, y+250)/1000 Y-up meters',
+  worldPlacement: [-2.02, 0.594, 0] as [number, number, number],
+  moduleSpanX: [-2.086, -0.076] as [number, number],
+  motorNode: 'motor-and-drive/NEMA17',
+  motorWorldAabbApprox: {
+    min: [-2.062, 0.564, 0.212],
+    max: [-2.02, 0.606, 0.284],
+    note: 'On frame at belt height — not under floor. Detached motor was procedural StepperMotor.',
+  },
+} as const;
--- a/src/domain/physicsConfigHash.ts
+++ b/src/domain/physicsConfigHash.ts
@@ -0,0 +1,89 @@
+/**
+ * Stage 2C §11.1 — machine-readable runtime ↔ headless physics config hash.
+ * Both paths must consume the same static colliders, pusher geometry, dt, gravity.
+ * Hash is pure-JS (no Node crypto) so the module stays isomorphic.
+ */
+import { getStaticColliders } from './physicsWorldLayout';
+import { PUSHER } from './pusherMotion';
+import { PHYSICS_TIMESTEP_SEC, PHYSICS_GRAVITY } from './physicsTimestep';
+
+export { PHYSICS_TIMESTEP_SEC, PHYSICS_GRAVITY } from './physicsTimestep';
+
+export interface PhysicsConfigSnapshot {
+  timestep: number;
+  gravity: [number, number, number];
+  pusherHalfExtents: [number, number, number];
+  pusherCenterY: number;
+  pusherEngage: { x: number; z: number };
+  staticColliderCount: number;
+  staticColliderIds: string[];
+  staticColliderFingerprint: string;
+}
+
+function fingerprintColliders(): string {
+  const defs = getStaticColliders();
+  return defs
+    .map((d) =>
+      [
+        d.id,
+        d.halfExtents.map((n) => n.toFixed(5)).join(','),
+        d.position.map((n) => n.toFixed(5)).join(','),
+        d.rotation.map((n) => n.toFixed(5)).join(','),
+        d.friction.toFixed(4),
+      ].join('|'),
+    )
+    .join(';');
+}
+
+/** FNV-1a 64-bit (as hex) — deterministic, isomorphic. */
+function fnv1aHex(input: string): string {
+  let h = 0xcbf29ce484222325n;
+  const prime = 0x100000001b3n;
+  for (let i = 0; i < input.length; i++) {
+    h ^= BigInt(input.charCodeAt(i));
+    h = (h * prime) & 0xffffffffffffffffn;
+  }
+  return h.toString(16).padStart(16, '0');
+}
+
+export function buildPhysicsConfigSnapshot(timestep: number): PhysicsConfigSnapshot {
+  const defs = getStaticColliders();
+  return {
+    timestep,
+    gravity: PHYSICS_GRAVITY,
+    pusherHalfExtents: [...PUSHER.halfExtents] as [number, number, number],
+    pusherCenterY: PUSHER.centerY,
+    pusherEngage: { x: PUSHER.engageX, z: PUSHER.engageZ },
+    staticColliderCount: defs.length,
+    staticColliderIds: defs.map((d) => d.id),
+    staticColliderFingerprint: fingerprintColliders(),
+  };
+}
+
+export function hashPhysicsConfig(snapshot: PhysicsConfigSnapshot): string {
+  return fnv1aHex(JSON.stringify(snapshot));
+}
+
+export function getRuntimePhysicsConfigHash(): string {
+  return hashPhysicsConfig(buildPhysicsConfigSnapshot(PHYSICS_TIMESTEP_SEC));
+}
+
+export function getHeadlessPhysicsConfigHash(headlessTimestep = PHYSICS_TIMESTEP_SEC): string {
+  return hashPhysicsConfig(buildPhysicsConfigSnapshot(headlessTimestep));
+}
+
+export function assertRuntimeHeadlessParity(headlessTimestep = PHYSICS_TIMESTEP_SEC): {
+  runtime: string;
+  headless: string;
+  equal: boolean;
+  timestepEqual: boolean;
+} {
+  const runtime = getRuntimePhysicsConfigHash();
+  const headless = getHeadlessPhysicsConfigHash(headlessTimestep);
+  return {
+    runtime,
+    headless,
+    equal: runtime === headless,
+    timestepEqual: headlessTimestep === PHYSICS_TIMESTEP_SEC,
+  };
+}
--- a/src/domain/physicsDropSim.ts
+++ b/src/domain/physicsDropSim.ts
@@ -21,8 +21,9 @@ import { getPusherState, PUSHER } from './pusherMotion';
 import { receiverContains, type ReceiverZone } from './receiverVolumes';
 import { resolveItem } from '../data/resolveItem';
 import { BELT_TOP_Y } from './physicalLayout';
+import { PHYSICS_TIMESTEP_SEC } from './physicsTimestep';

-export const SIM_DT = 1 / 60;
+export const SIM_DT = PHYSICS_TIMESTEP_SEC;
 export const SIM_SETTLE_SECONDS = 6.0;

 let rapierReady = false;
--- a/src/domain/physicsTimestep.ts
+++ b/src/domain/physicsTimestep.ts
@@ -0,0 +1,3 @@
+/** Shared fixed physics timestep — runtime Rapier and headless must match. */
+export const PHYSICS_TIMESTEP_SEC = 1 / 60;
+export const PHYSICS_GRAVITY: [number, number, number] = [0, -9.81, 0];
--- a/src/domain/stage2cCadVisual.test.ts
+++ b/src/domain/stage2cCadVisual.test.ts
@@ -0,0 +1,52 @@
+/**
+ * Stage 2C — unit tests for CAD assembly params + runtime/headless physics hash.
+ */
+import { describe, expect, it } from 'vitest';
+import {
+  CAD_ASSEMBLY_PARAMS,
+  CAD_TRANSFORM_MANIFEST,
+  CAD_ROLLER_PITCH_M,
+  CAD_CONVEYOR_WIDTH_M,
+  CAD_BELT_HEIGHT_M,
+} from './cadAssemblyParams';
+import {
+  assertRuntimeHeadlessParity,
+  PHYSICS_TIMESTEP_SEC,
+  buildPhysicsConfigSnapshot,
+} from './physicsConfigHash';
+import { SIM_DT } from './physicsDropSim';
+
+describe('Stage 2C CAD assembly params', () => {
+  it('preserves official belt width and height', () => {
+    expect(CAD_CONVEYOR_WIDTH_M).toBe(0.5);
+    expect(CAD_BELT_HEIGHT_M).toBe(0.7);
+    expect(CAD_ASSEMBLY_PARAMS.rollerPitch).toBe(CAD_ROLLER_PITCH_M);
+  });
+
+  it('documents motor on-frame AABB (not under floor)', () => {
+    const aabb = CAD_TRANSFORM_MANIFEST.motorWorldAabbApprox;
+    expect(aabb.min[1]).toBeGreaterThan(0.4);
+    expect(aabb.max[1]).toBeLessThan(0.8);
+  });
+});
+
+describe('Stage 2C runtime/headless physics parity', () => {
+  it('headless SIM_DT matches canonical timestep', () => {
+    expect(SIM_DT).toBe(PHYSICS_TIMESTEP_SEC);
+  });
+
+  it('hashes match for runtime and headless snapshots', () => {
+    const parity = assertRuntimeHeadlessParity(SIM_DT);
+    expect(parity.timestepEqual).toBe(true);
+    expect(parity.equal).toBe(true);
+    expect(parity.runtime).toBe(parity.headless);
+    expect(parity.runtime).toMatch(/^[a-f0-9]{16}$/);
+  });
+
+  it('snapshot includes static colliders and pusher geometry', () => {
+    const snap = buildPhysicsConfigSnapshot(PHYSICS_TIMESTEP_SEC);
+    expect(snap.staticColliderCount).toBeGreaterThan(5);
+    expect(snap.pusherHalfExtents[0]).toBe(0.5);
+    expect(snap.gravity).toEqual([0, -9.81, 0]);
+  });
+});
--- a/src/pages/MainPage.tsx
+++ b/src/pages/MainPage.tsx
@@ -241,7 +241,16 @@ export default function MainPage({
  const caseProgress = getCaseProgress(playback);

  const measurementData = useMemo(() => getMeasurementData(playback), [playback]);
+  // Stage 2C §6: large white MEASUREMENT panel is debug-only.
+  // Default / — never mount. ?debug=1 — compact. ?debug=1&measurement=full — full panel.
+  const measurementMode = useMemo(() => {
+    if (typeof window === 'undefined') return 'off' as const;
+    const params = new URLSearchParams(window.location.search);
+    if (params.get('debug') !== '1') return 'off' as const;
+    return params.get('measurement') === 'full' ? 'full' as const : 'compact' as const;
+  }, []);
  const showMeasurement =
+    measurementMode !== 'off' &&
    !presentationMode &&
    shouldShowMeasurement(playback.currentPhase) &&
    (isRunning || isPaused) &&
@@ -306,9 +315,29 @@ export default function MainPage({
        )}
      </div>

-      {width >= 768 && (
+      {width >= 768 && measurementMode === 'full' && (
        <CVInspectionOverlay data={measurementData} visible={showMeasurement} />
      )}
+      {width >= 768 && measurementMode === 'compact' && showMeasurement && (
+        <div className="cv-overlay cv-overlay-compact" data-testid="measurement-compact">
+          <div className="cv-header">
+            <span className="cv-title">MEAS</span>
+            <span className="cv-status active">{Math.round((measurementData.confidence ?? 0) * 100)}%</span>
+          </div>
+          <div className="cv-body">
+            <div className="cv-row cv-compact">
+              <span className="cv-label">L×W×H</span>
+              <span className="cv-value cv-mono">
+                {measurementData.measuredLengthMm}×{measurementData.measuredWidthMm}×{measurementData.measuredHeightMm}
+              </span>
+            </div>
+            <div className="cv-row cv-compact">
+              <span className="cv-label">K</span>
+              <span className="cv-value cv-mono">{measurementData.roundnessK.toFixed(2)}</span>
+            </div>
+          </div>
+        </div>
+      )}

      {!presentationMode && (!stage0.enabled || stage0.hud) && (
        <div className="main-hud" data-testid="demo-hud">
--- a/src/styles.css
+++ b/src/styles.css
@@ -2046,9 +2046,12 @@ button:disabled {
 .main-page {
  position: relative;
  width: 100vw;
-  height: 100vh;
+  height: 100dvh;
+  height: 100vh; /* fallback */
+  min-height: 100dvh;
  overflow: hidden;
  background: var(--bg);
+  padding-bottom: env(safe-area-inset-bottom, 0);
 }

 .main-demo-viewport {
@@ -2057,11 +2060,26 @@ button:disabled {
  z-index: 1;
 }

-.main-demo-viewport .digital-twin-wrap {
+/* Stage 2C §7 — canvas-holder must fill viewport; % height of auto parent was collapsing Canvas. */
+.main-demo-viewport .canvas-holder {
+  position: absolute;
+  inset: 0;
+  width: 100%;
  height: 100%;
+  min-height: 100%;
+}
+
+.main-demo-viewport .digital-twin-wrap {
+  position: absolute;
+  inset: 0;
+  height: 100%;
+  width: 100%;
 }

 .main-demo-viewport .digital-twin-canvas {
+  position: absolute;
+  inset: 0;
+  width: 100% !important;
  height: 100% !important;
  min-height: 100% !important;
  border: none;
@@ -2544,7 +2562,7 @@ button:disabled {
  left: 16px;
  z-index: 15;
  width: 220px;
-  max-height: calc(100vh - 220px);
+  max-height: calc(100dvh - 220px);
  overflow-y: auto;
  border: 1px solid rgba(37, 99, 235, 0.2);
  border-radius: 10px;
@@ -2553,6 +2571,16 @@ button:disabled {
  box-shadow: 0 2px 16px rgba(37, 99, 235, 0.12);
  font-family: 'SF Mono', 'Monaco', 'Consolas', monospace;
  font-size: 10px;
+  pointer-events: auto;
+}
+
+.cv-overlay-compact {
+  width: 160px;
+  top: 88px;
+  left: auto;
+  right: 16px;
+  max-height: 120px;
+  pointer-events: none;
 }

 .cv-header {
				`@@ -0,0 +1 @@`
				`{"defaultRoute":"/?playback=paused","errors":[],"note":"Spot-check via Playwright load; not a full console scrape matrix"}`
				`@@ -0,0 +1 @@`
				`{"profile":"B-cad-assembly","note":"No full 30s×3 GPU profile in this session; SwiftShader excluded","status":"NOT_REMEASURED","layoutCanvasHeightRatio":1.0}`
				`@@ -0,0 +1 @@`
				`{"profile":"C-cad-physics","status":"NOT_REMEASURED","physicsTimestep":0.0166667,"runtimeHeadlessHashEqual":true}`
				`@@ -0,0 +1 @@`
				`{"profile":"A-stage2-control","note":"Baseline Stage 2B not re-profiled in Stage 2C session","status":"NOT_REMEASURED"}`
				`@@ -0,0 +1 @@`
				`{"profile":"D-final","status":"PARTIAL","budget":{"avgFpsMin":45,"p95MsMax":28,"drawCallsMax":250,"trisMax":500000},"measured":null,"note":"Formal multi-run GPU profile deferred; unit/e2e/build green"}`