feat(rebar): 철근표 간격·실간격을 입력과 연동, 근거는 기본값/입력

- C1–C8: 간격 2 × 주철근 기본간격, 실간격 기본간격
- C9·C11 · C10 · C12·C13 · C14: 전단·측면·C14 간격 입력
- S1·S2: 블록 철근 간격 입력
- 근거: 관련 입력이 모두 기본값이면 '기본값', 하나라도 바뀌면 '입력'
- 입력이 없는 행(C15·C16, P3~P5, 커플러)은 기존 고정값 유지

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

src/core/rebar/summary.ts

@@ -1,5 +1,6 @@
 import type { PierModel } from '../geometry';
-import { barLength, bearingBlockRebar, totals } from './bearing-block';
+import { barLength, bearingBlockRebar, DEFAULT_BLOCK_REBAR, totals } from './bearing-block';
+import { DEFAULT_COPING_REBAR } from './coping-settings';
 import { bottomPiece, topBarLength, widthLayout } from './coping-main';
 import { shearBars, shearBarsMulti, copingSideBars, SIDE_HOOK_LEG, c14Bars, c14Length, stairBars, stepDevLength, undersideAt, shearULength, capLength, PIECES_PER_POSITION } from './coping';
 import { sideRowLevels } from '../coping-geom';
@@ -117,6 +118,37 @@ function footingBarList(Lf: number, Wf: number, Hf: number, columnX: number[]):
 
 type RawRow = Omit<RebarRow, 'spacing' | 'actual' | 'position' | 'direction' | 'shape' | 'basis'>;
 
+const MAIN_BARS = ['C1', 'C2', 'C3', 'C4', 'C5', 'C6', 'C7', 'C8'];
+
+/**
+ * 간격·실간격 and 근거 of the rows that have a spacing input (승인 2026-10-26). 간격 is the design spacing (the cycle
+ * pitch for C1–C8, which alternate, so 2 × 기본간격); 실간격 is the spacing of the bars themselves. The basis is '기본값'
+ * when every input behind the row is at its default, otherwise '입력'.
+ */
+export function linkedSpacing(name: string, model: PierModel): Pick<RebarRow, 'spacing' | 'actual' | 'basis'> | undefined {
+  const c = model.copingRebar;
+  const d = DEFAULT_COPING_REBAR;
+  const b = model.blockRebar;
+  const bd = DEFAULT_BLOCK_REBAR;
+  const basis = (changed: boolean): Basis => (changed ? 'input' : 'default');
+  if (MAIN_BARS.includes(name)) {
+    return { spacing: String(2 * c.mainSpacing), actual: String(c.mainSpacing), basis: basis(c.mainSpacing !== d.mainSpacing) };
+  }
+  if (name === 'C9' || name === 'C11') return { spacing: String(c.spacingS), actual: String(c.spacingS), basis: basis(c.spacingS !== d.spacingS) };
+  if (name === 'C10') return { spacing: String(c.spacingL), actual: String(c.spacingL), basis: basis(c.spacingL !== d.spacingL) };
+  if (name === 'C12' || name === 'C13') return { spacing: String(c.sideSpacing), actual: String(c.sideSpacing), basis: basis(c.sideSpacing !== d.sideSpacing) };
+  if (name === 'C14') {
+    return {
+      spacing: `${c.c14UpperSpacing} / ${c.c14LowerSpacing}`,
+      actual: String(c.c14UpperSpacing),
+      basis: basis(c.c14UpperSpacing !== d.c14UpperSpacing || c.c14LowerSpacing !== d.c14LowerSpacing),
+    };
+  }
+  if (name === 'S1') return { spacing: String(b.spacingS1), actual: String(b.spacingS1), basis: basis(b.spacingS1 !== bd.spacingS1) };
+  if (name === 'S2') return { spacing: String(b.spacingS2), actual: String(b.spacingS2), basis: basis(b.spacingS2 !== bd.spacingS2) };
+  return undefined;
+}
+
 export function rebarSummary(
   model: PierModel,
   common: Material = DEFAULT_MATERIAL,
@@ -256,7 +288,10 @@ export function rebarSummary(
   } else {
     warnings.push({ code: 'RB-F00', message: '현장타설말뚝은 확대기초가 없어 확대기초 철근을 만들지 않습니다.', target: 'footing' });
   }
-  // Table metadata per bar (구분·간격·실간격·위치·방향·형상·근거).
-  const withMeta = rows.map((r) => ({ ...r, ...(META[r.name] ?? FALLBACK) }));
+  // Table metadata per bar (구분·간격·실간격·위치·방향·형상·근거). The spacing rows take their values from the inputs (승인 2026-10-26).
+  const withMeta = rows.map((r) => {
+    const linked = linkedSpacing(r.name, model);
+    return { ...r, ...(META[r.name] ?? FALLBACK), ...(linked ?? {}) };
+  });
   return { rows: withMeta, warnings: warnings.map((w) => ({ ...w, target: w.target ?? 'common' })) };
 }

tests/rebar-coping-main.test.ts

@@ -34,6 +34,22 @@ describe('C1–C8 상·하면 주철근 (코핑철근.md §5, plan C3)', () => {
     expect(w120.count).toBe(25);
   });
 
+  it('철근표 간격: P1 기본값은 250 / 125 · 기본값 근거, 기본간격 140이면 280 / 140 · 입력 근거', () => {
+    const base = rebarSummary(buildPier(loadP1())).rows;
+    const c1 = base.find((r) => r.name === 'C1')!;
+    expect([c1.spacing, c1.actual, c1.basis]).toEqual(['250', '125', 'default']);
+    const c12 = base.find((r) => r.name === 'C12')!;
+    expect(c12.basis).toBe('default');
+
+    const m = buildPier({ ...loadP1(), copingRebar: { mainSpacing: 140 }, blockRebar: { spacingS1: 130 } });
+    const rows = rebarSummary(m).rows;
+    const c8 = rows.find((r) => r.name === 'C8')!;
+    expect([c8.spacing, c8.actual, c8.basis]).toEqual(['280', '140', 'input']);
+    expect(rows.find((r) => r.name === 'C12')!.basis).toBe('default');
+    const s1 = rows.find((r) => r.name === 'S1')!;
+    expect([s1.spacing, s1.actual, s1.basis]).toEqual(['130', '130', 'input']);
+  });
+
   it('CP04: the default P1 has an even count (no warning); 기본간격 120 gives an odd count and a CP04 warning', () => {
     const base = rebarSummary(buildPier(loadP1())).warnings.filter((w) => w.code === 'CP04');
     expect(base).toEqual([]);