feat(abut): ③ 교대 반투명 보기 · 교대 저판 전용 fck

- ③ 철근배근에서 교대 부재·지반도 교각처럼 반투명(0.5, 깊이 쓰기 끔). setRebarViewOn으로 공통화, 끄면 원래 불투명도 복원(지반 0.35 유지)
- 교대 저판 fck(abutFooting, 기본 27)를 교각 기초 fck와 분리. ② 확대기초·말뚝 카드에 입력, ③ 저판 배근·이음 길이에 반영
- 테스트 713개 통과

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/abut-scene.test.ts

@@ -8,6 +8,7 @@ import { parseAbutments, toAbutInput } from '../src/core/abut/parse';
 import { buildMembers } from '../src/core/abut/members';
 import { buildWings } from '../src/core/abut/wings';
 import { abutPlacement, buildAbutGroup, cameraForBox, covers } from '../src/view/abut-scene';
+import { setRebarViewOn } from '../src/view/scene';
 import type { TerrainGrid } from '../src/core/ground-model';
 
 const RAG = fileURLToPath(new URL('../../../RAG/운곡교P1입력.xlsx', import.meta.url));
@@ -132,3 +133,37 @@ describe('교대 선택 시 카메라', () => {
     expect(cam.position.distanceTo(cam.target)).toBeGreaterThan(12);
   });
 });
+
+describe('③ 배근 보기 반투명 (교각과 같음, 2026-11-04)', () => {
+  const g = buildAbutGroup(model, members, wings, undefined, GROUND_EL);
+  const mats = () => {
+    const out: THREE.MeshStandardMaterial[] = [];
+    g.traverse((o) => {
+      if (o instanceof THREE.Mesh) out.push(o.material as THREE.MeshStandardMaterial);
+    });
+    return out;
+  };
+  const ground = () => (g.getObjectByName('ground') as THREE.Group).children[0] as THREE.Mesh;
+
+  it('turns every member and the ground to half opacity with depth writes off', () => {
+    setRebarViewOn(g, true);
+    for (const m of mats()) {
+      expect(m.opacity).toBe(0.5);
+      expect(m.transparent).toBe(true);
+      expect(m.depthWrite).toBe(false);
+    }
+  });
+
+  it('restores each part: members opaque, the ground at 0.35 without depth writes', () => {
+    setRebarViewOn(g, false);
+    const groundMat = ground().material as THREE.MeshStandardMaterial;
+    for (const m of mats()) {
+      if (m === groundMat) continue;
+      expect(m.opacity).toBe(1);
+      expect(m.transparent).toBe(false);
+      expect(m.depthWrite).toBe(true);
+    }
+    expect(groundMat.opacity).toBe(0.35);
+    expect(groundMat.depthWrite).toBe(false);
+  });
+});

tests/member-fck.test.ts

@@ -1,15 +1,15 @@
 import { describe, expect, it } from 'vitest';
-import { fckChanged, IMPORTED_FCK } from '../src/core/rebar/common';
+import { DEFAULT_MATERIAL, fckChanged, IMPORTED_FCK, materialFor } from '../src/core/rebar/common';
 
-describe('IMPORTED_FCK (교각도 기준 부재별 기본 fck)', () => {
-  it('is 40 for 기둥·코핑 and 27 for 확대기초', () => {
-    expect(IMPORTED_FCK).toEqual({ column: 40, coping: 40, footing: 27 });
+describe('IMPORTED_FCK (교각도 · 교대도 기준 부재별 기본 fck)', () => {
+  it('is 40 for 기둥·코핑, 27 for 확대기초 and 27 for 교대 저판', () => {
+    expect(IMPORTED_FCK).toEqual({ column: 40, coping: 40, footing: 27, abutFooting: 27 });
   });
 });
 
 describe('fckChanged (기본과 다르면 주황색)', () => {
   it('is false at the imported default', () => {
-    expect(fckChanged({ column: 40, coping: 40, footing: 27 }, 'coping')).toBe(false);
+    expect(fckChanged({ column: 40, coping: 40, footing: 27, abutFooting: 27 }, 'coping')).toBe(false);
   });
 
   it('is true when the member differs from its imported default', () => {
@@ -21,3 +21,15 @@ describe('fckChanged (기본과 다르면 주황색)', () => {
     expect(fckChanged({}, 'column')).toBe(false);
   });
 });
+
+describe('교대 저판 fck (교각 기초와 별도, 2026-11-04)', () => {
+  it('follows abutFooting, not the pier footing', () => {
+    const byMember = { footing: 30, abutFooting: 35 };
+    expect(materialFor(DEFAULT_MATERIAL, byMember, 'abutFooting').fck).toBe(35);
+    expect(materialFor(DEFAULT_MATERIAL, byMember, 'footing').fck).toBe(30);
+  });
+
+  it('falls back to the 공통 fck when unset (old project files)', () => {
+    expect(materialFor({ ...DEFAULT_MATERIAL, fck: 24 }, { footing: 30 }, 'abutFooting').fck).toBe(24);
+  });
+});