fix(bearing): show only the outer block margins as C4 and C5

- A 일체 pair's inner sides face the other bearing, so they are not C4 or C5:
  they are null and shown as "—" in the 배치 규칙 table.
- The table headings now describe the 교축 margins (bearing to the outer block edge).

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

src/core/bearing-layout.ts

@@ -12,10 +12,10 @@ export const PAIR_ECCENTRICITY_LIMIT_MM = 100;
 export interface EdgeDistance {
   no: number;
   row: BlockModel['row'];
-  /** 교축 방향: 받침 중심에서 블록의 낮은 쪽(−n) 연단까지 (mm) = C4. */
-  leftMm: number;
-  /** 교축 방향: 받침 중심에서 블록의 높은 쪽(+n) 연단까지 (mm) = C5. */
-  rightMm: number;
+  /** 교축 방향: 받침 중심에서 블록의 낮은 쪽(−n) 연단까지 (mm) = C4. null = 쌍 안쪽 (C4·C5 아님). */
+  leftMm: number | null;
+  /** 교축 방향: 받침 중심에서 블록의 높은 쪽(+n) 연단까지 (mm) = C5. null = 쌍 안쪽 (C4·C5 아님). */
+  rightMm: number | null;
 }
 
 export interface PairEccentricity {
@@ -37,10 +37,18 @@ export function bearingEdgeDistances(m: PierModel): EdgeDistance[] {
   const HALF_INTEGRATED = 1.25; // 2500 / 2, m
   return m.blocks.map((b) => {
     const host = m.integratedBlocks.find((x) => (b.row === '전열' ? x.frontNo : x.backNo) === b.no);
-    const half = host ? HALF_INTEGRATED : HALF_SEPARATE;
-    const low = host ? host.n - half : b.n - half;
-    const high = host ? host.n + half : b.n + half;
-    return { no: b.no, row: b.row, leftMm: (b.n - low) * 1000, rightMm: (high - b.n) * 1000 };
+    if (!host) {
+      return { no: b.no, row: b.row, leftMm: (HALF_SEPARATE) * 1000, rightMm: HALF_SEPARATE * 1000 };
+    }
+    // 일체: only the outer edges are C4 (front, low side) and C5 (back, high side); the inner side faces the other bearing.
+    const low = host.n - HALF_INTEGRATED;
+    const high = host.n + HALF_INTEGRATED;
+    return {
+      no: b.no,
+      row: b.row,
+      leftMm: b.row === '전열' ? (b.n - low) * 1000 : null,
+      rightMm: b.row === '후열' ? (high - b.n) * 1000 : null,
+    };
   });
 }
 

src/main.ts

@@ -1576,13 +1576,14 @@ function renderBearingLayout(wrap: HTMLDivElement, pier: Pier): void {
   const table = el('table', undefined, 'grid-table rebar-table');
   const head = el('thead');
   const hr = el('tr');
-  for (const h of ['받침', '열', 'C4 (코핑 시작 ↔ 받침, mm)', 'C5 (받침 ↔ 코핑 끝, mm)']) hr.appendChild(el('th', h));
+  for (const h of ['받침', '열', 'C4 (교축 · 받침 ↔ 블록 바깥 연단, mm)', 'C5 (교축 · 받침 ↔ 블록 바깥 연단, mm)']) hr.appendChild(el('th', h));
   head.appendChild(hr);
   table.appendChild(head);
   const body = el('tbody');
   for (const e of edges) {
     const tr = el('tr');
-    for (const v of [String(e.no), e.row, e.leftMm.toFixed(0), e.rightMm.toFixed(0)]) tr.appendChild(el('td', v));
+    const fmt = (v: number | null) => (v === null ? '—' : v.toFixed(0));
+    for (const v of [String(e.no), e.row, fmt(e.leftMm), fmt(e.rightMm)]) tr.appendChild(el('td', v));
     body.appendChild(tr);
   }
   table.appendChild(body);

src/view/bearing-plan-svg.ts

@@ -61,8 +61,8 @@ export function bearingPlanSvg(m: PierModel, pairIndex: number, overlay?: Bearin
   const dist = bearingEdgeDistances(m);
   const d = (no: number) => dist.find((x) => x.no === no)!;
   parts.push(`<text x="${(X(f.n) + X(k.n)) / 2}" y="${Y(f.s) + 180}" text-anchor="middle" font-size="90" fill="#18212B">C2 ${Math.round(Math.abs(k.n - f.n) * 1000)}</text>`);
-  parts.push(`<text x="${X(f.n) - 760}" y="${Y(f.s)}" text-anchor="end" font-size="90" fill="#18212B">C4 ${Math.round(d(f.no).leftMm)}</text>`);
-  parts.push(`<text x="${X(k.n) + 760}" y="${Y(k.s)}" font-size="90" fill="#18212B">C5 ${Math.round(d(k.no).rightMm)}</text>`);
+  parts.push(`<text x="${X(f.n) - 760}" y="${Y(f.s)}" text-anchor="end" font-size="90" fill="#18212B">C4 ${Math.round(d(f.no).leftMm ?? 0)}</text>`);
+  parts.push(`<text x="${X(k.n) + 760}" y="${Y(k.s)}" font-size="90" fill="#18212B">C5 ${Math.round(d(k.no).rightMm ?? 0)}</text>`);
 
   return `<svg viewBox="-1800 -1000 3600 2000" width="100%" style="max-width: 560px; height: auto" role="img" aria-label="교량받침 상세 평면: 쌍 ${pair.frontNo}·${pair.backNo}, 블록 윤곽, 솔플레이트, 도면값 겹쳐 보기">${parts.join('')}</svg>`;
 }

tests/bearing-layout.test.ts

@@ -28,6 +28,9 @@ describe('받침 배치 규칙 (승인 2026-10-26)', () => {
     // The 2500 block is centred on the pair midpoint, so the outer margins are 601 (within the 5 mm drawing tolerance of 600).
     expect(d.find((x) => x.no === 1 && x.row === '전열')!.leftMm).toBeCloseTo(600, -1);
     expect(d.find((x) => x.no === 6 && x.row === '후열')!.rightMm).toBeCloseTo(600, -1);
+    // the inner sides face the other bearing of the pair: no C4 or C5 there
+    expect(d.find((x) => x.no === 1 && x.row === '전열')!.rightMm).toBeNull();
+    expect(d.find((x) => x.no === 6 && x.row === '후열')!.leftMm).toBeNull();
   });
 
   it('the front and back bearings of one number are about 85 mm apart on P1, so 일체 is allowed', () => {