feat(bearing): model C4/C5 and the front–back pair eccentricity (승인 2026-10-26)

- C4/C5 = distance from the coping edge to the bearing centre along the
  coping length, from the model; the drawing value is for comparison only.
- A pair is a front and back bearing of the same order within their row. A
  pair with an eccentricity above 100 mm forbids 일체 (분리 first).
- ② bearing card: read-only table of C4/C5 and the pair eccentricities.
- The 일체 block model is not built yet.

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

src/core/bearing-layout.ts

@@ -0,0 +1,55 @@
+import type { BlockModel, PierModel } from './geometry';
+
+/**
+ * 받침 배치 규칙 (승인 2026-10-26).
+ * - C4·C5: 코핑 가장자리와 받침 중심(받침좌표) 사이 거리, 교각축 방향 (s). 모델값을 쓰고 도면값과 비교한다.
+ * - 일체: 같은 순서끼리 (전열 1 · 후열 1, 전열 2 · 후열 2 …, 각 열의 번호 순) 두 받침의 편심거리가 100 mm를 넘으면 분리를 우선한다.
+ *   (P1 은 전열 1–5, 후열 6–10 으로 번호가 매겨져 있어서 번호 자체가 아니라 열 안의 순서로 짝짓는다.)
+ *   편심거리 = 두 받침 중심의 교각축 방향 차이 |s(전열) − s(후열)|.
+ */
+export const PAIR_ECCENTRICITY_LIMIT_MM = 100;
+
+export interface EdgeDistance {
+  no: number;
+  row: BlockModel['row'];
+  /** 코핑 시작(s = 0)에서 받침 중심까지 (mm). */
+  leftMm: number;
+  /** 받침 중심에서 코핑 끝(s = L)까지 (mm). */
+  rightMm: number;
+}
+
+export interface PairEccentricity {
+  /** 전열 번호 and 후열 번호 of the pair. */
+  frontNo: number;
+  backNo: number;
+  eccentricityMm: number;
+  /** true: 편심이 한계 이하, 일체 배치 가능. */
+  allowed: boolean;
+}
+
+/** C4·C5 from the model: distances from each coping edge to each bearing centre, along the coping length (mm). */
+export function bearingEdgeDistances(m: PierModel): EdgeDistance[] {
+  const L = m.copingL * 1000;
+  return m.blocks.map((b) => ({
+    no: b.no,
+    row: b.row,
+    leftMm: b.s * 1000,
+    rightMm: L - b.s * 1000,
+  }));
+}
+
+/**
+ * Pairs by order within each row (전열 1 · 후열 1, 2 · 2 …) with their eccentricity.
+ * A bearing left without a partner (the rows have different counts) is not paired.
+ */
+export function pairEccentricities(blocks: BlockModel[]): PairEccentricity[] {
+  const byNo = (a: BlockModel, b: BlockModel) => a.no - b.no;
+  const front = blocks.filter((b) => b.row === '전열').sort(byNo);
+  const back = blocks.filter((b) => b.row === '후열').sort(byNo);
+  const out: PairEccentricity[] = [];
+  for (let i = 0; i < Math.min(front.length, back.length); i++) {
+    const e = Math.abs(front[i].s - back[i].s) * 1000;
+    out.push({ frontNo: front[i].no, backNo: back[i].no, eccentricityMm: e, allowed: e <= PAIR_ECCENTRICITY_LIMIT_MM });
+  }
+  return out;
+}

src/main.ts

@@ -18,6 +18,7 @@ import { buildQuantity, quantityRows, type Quantity, type QuantityLine } from '.
 import { parseDrawingRows } from './core/drawing-import';
 import { groundElFor, parseGroundModel, strataRowsFor, type GroundModelFile } from './core/ground-model';
 import { CORROSION_ALLOWANCE_MM, parseNValue, SEA_DATUM, STRATA_NAMES } from './core/ground';
+import { bearingEdgeDistances, PAIR_ECCENTRICITY_LIMIT_MM, pairEccentricities } from './core/bearing-layout';
 import { groundSectionSvg } from './view/ground-svg';
 import { parseBearingElevationTable, parseSolplateTable, readDxfTexts } from './core/dxf-table';
 import { columnDiameterIssues } from './core/column-check';
@@ -1503,6 +1504,33 @@ function renderBearingBasis(wrap: HTMLDivElement, pier: Pier): void {
   }
 }
 
+/**
+ * 받침 배치 (승인 2026-10-26, read-only): C4·C5 from the model (coping edge ↔ bearing centre, 교각축 방향) and the
+ * eccentricity of each front–back pair (일체 allowed up to 100 mm, otherwise 분리 first).
+ */
+function renderBearingLayout(wrap: HTMLDivElement, pier: Pier): void {
+  if (!pier.model) return;
+  wrap.appendChild(el('p', `배치 규칙 (모델값 · 편심 한계 ${PAIR_ECCENTRICITY_LIMIT_MM} mm)`, 'lbl'));
+  const edges = bearingEdgeDistances(pier.model);
+  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));
+  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));
+    body.appendChild(tr);
+  }
+  table.appendChild(body);
+  wrap.appendChild(el('div', undefined, 'table-scroll')).appendChild(table);
+  const pairs = pairEccentricities(pier.model.blocks);
+  const forced = pairs.filter((p) => !p.allowed).length;
+  wrap.appendChild(el('p', `쌍 편심 (전열 k · 후열 k, 교각축 방향): 최대 ${Math.max(...pairs.map((p) => p.eccentricityMm)).toFixed(0)} mm · ${forced === 0 ? '모든 쌍 일체 가능' : `${forced}쌍은 편심 초과 → 분리 우선`}`, 'muted small'));
+}
+
 /** Text of one tracked value in the 변경 list. */
 function valueText(key: EditableKey, v: unknown): string {
   if (v === undefined || v === null) return '없음';
@@ -1776,6 +1804,7 @@ function renderBearingRef(box: HTMLDivElement, pier: Pier): void {
     renderAll();
   });
   wrap.appendChild(typeInput);
+  renderBearingLayout(wrap, pier);
   wrap.appendChild(el('p', '공통 규칙 (입력 · 기본값 = 도면값)', 'lbl'));
   const rules: [keyof BearingRules, string][] = [['h2', '모르타르 h2 (mm)'], ['h3', '받침 높이 h3 (mm)'], ['T', '솔플레이트 중심 T (mm)'], ['margin', '솔플 여유 (mm)']];
   const grid = el('div', undefined, 'edit-row');

tests/bearing-layout.test.ts

@@ -0,0 +1,48 @@
+import { describe, expect, it } from 'vitest';
+import { buildPier, type BlockModel } from '../src/core/geometry';
+import { bearingEdgeDistances, PAIR_ECCENTRICITY_LIMIT_MM, pairEccentricities } from '../src/core/bearing-layout';
+import { loadP1 } from './helpers';
+
+const model = buildPier(loadP1());
+
+function block(no: number, row: '전열' | '후열', s: number): BlockModel {
+  return { no, row, s, n: 0, k: 0, g: 0, bottom: 0, top: 0, padTop: 0, rowSkewDeg: 0 } as BlockModel;
+}
+
+describe('받침 배치 규칙 (승인 2026-10-26)', () => {
+  it('C4 and C5 from the model: distances from each coping edge to the bearing centre (P1 ≈ 943 / 950 mm)', () => {
+    const d = bearingEdgeDistances(model);
+    expect(d).toHaveLength(10);
+    const first = d.find((x) => x.no === 1 && x.row === '전열')!;
+    expect(first.leftMm).toBeCloseTo(943, 0);
+    expect(first.rightMm).toBeCloseTo(12000 - 943, 0);
+    // the two ends of one bearing sum to the coping length
+    for (const x of d) expect(x.leftMm + x.rightMm).toBeCloseTo(12000, 6);
+  });
+
+  it('the front and back bearings of one number are about 85 mm apart on P1, so 일체 is allowed', () => {
+    const pairs = pairEccentricities(model.blocks);
+    expect(pairs).toHaveLength(5);
+    for (const p of pairs) {
+      expect(p.eccentricityMm).toBeGreaterThan(80);
+      expect(p.eccentricityMm).toBeLessThan(90);
+      expect(p.allowed).toBe(true);
+    }
+  });
+
+  it('an eccentricity above 100 mm forbids 일체 for that pair (분리 우선)', () => {
+    expect(PAIR_ECCENTRICITY_LIMIT_MM).toBe(100);
+    const pairs = pairEccentricities([block(1, '전열', 1.0), block(1, '후열', 1.12), block(2, '전열', 3), block(2, '후열', 3.09)]);
+    expect(pairs.find((p) => p.frontNo === 1)!.allowed).toBe(false);
+    expect(pairs.find((p) => p.frontNo === 2)!.allowed).toBe(true);
+  });
+
+  it('pairs by order within each row, so 전열 1 pairs with 후열 6 on P1 (numbers run on across the rows)', () => {
+    const pairs = pairEccentricities(model.blocks);
+    expect(pairs[0]).toMatchObject({ frontNo: 1, backNo: 6 });
+  });
+
+  it('a bearing left without a partner (the rows have different counts) is not paired', () => {
+    expect(pairEccentricities([block(1, '전열', 1), block(2, '전열', 3), block(6, '후열', 1.05)])).toHaveLength(1);
+  });
+});