feat(core): haunch-and-Level-300 coping underside, steel pile 609.6, W03/W04 checks

- Multi-column coping (2·3주형): underside between columns drops 300 below
  Level with 300 × 300 haunches (spec §4.5, Q3 추천안).
- Steel pipe pile diameter 609.6 mm (spec §4.5, Q5 추천안).
- Direct foundation keeps the 100 mm blinding concrete (Q4 추천안, test added).
- W03: bearing centre closer than half a block width to a step boundary.
- W04: block footprint outside the coping plan.

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

src/core/geometry.ts

@@ -6,6 +6,8 @@ export const DIM = {
   copingH1: 1.0,
   copingH2: 1.5,
   levelWidth: 2.1,
+  /** Multi-column coping: underside between columns sits this far below Level, with 45° haunches of the same size (spec §4.5, Q3 추천안). */
+  haunch: 0.3,
   padThickness: 0.05,
   padSize: 1.0,
   blockSize: 1.2,
@@ -14,7 +16,8 @@ export const DIM = {
   footingH: 2.0,
   blindingMargin: 0.2,
   blindingT: 0.1,
-  pileDiameter: 0.6,
+  /** 강관 609.6 × 12 (spec §4.5 강관 type, Q5 추천안 적용). */
+  pileDiameter: 0.6096,
   pileEnd: 0.7,
   pileSpacing: 2.25,
   /** Front/back EL difference below this is treated as no lateral step (spec §4.3, Q2). */
@@ -204,12 +207,24 @@ export function buildPier(input: PierInput): PierModel {
   const levelEnd = Math.max(...colS) + DIM.levelWidth / 2;
   if (levelStart < 0 || levelEnd > L) throw new Error('코핑 길이가 Level 구간보다 짧습니다.');
 
+  // Underside from the right end to the left end. Between columns (2·3주형) it drops 300 below Level with 300 × 300 haunches (spec §4.5, Q3).
+  const underside: [number, number][] = [[L, endBottom]];
+  const levelZones = [...colS].sort((a, b) => b - a).map((s) => [s - DIM.levelWidth / 2, s + DIM.levelWidth / 2] as const);
+  levelZones.forEach(([zoneStart, zoneEnd], k) => {
+    underside.push([zoneEnd, levelBottom], [zoneStart, levelBottom]);
+    const next = levelZones[k + 1];
+    if (!next) return;
+    const gap = zoneStart - next[1];
+    if (gap <= 2 * DIM.haunch) throw new Error('기둥 사이 간격이 헌치(300 × 2)보다 좁아 코핑 하면을 만들 수 없습니다.');
+    const lowerEl = levelBottom - DIM.haunch;
+    underside.push([zoneStart - DIM.haunch, lowerEl], [next[1] + DIM.haunch, lowerEl], [next[1], levelBottom]);
+  });
+
   const profile: [number, number][] = [[0, endBottom]];
   for (const seg of segments) {
     profile.push([seg.s0, seg.top], [seg.s1, seg.top]);
   }
-  profile.push([L, endBottom], [levelEnd, levelBottom], [levelStart, levelBottom], [0, endBottom]);
-  profile.pop(); // the last point repeats the first one
+  profile.push(...underside);
 
   const footingTop = input.foundationType === '현장타설말뚝' ? input.footingBottomEl : input.footingBottomEl + DIM.footingH;
   const columns: ColumnModel[] = colS.map((s) => ({

src/core/validate.ts

@@ -6,11 +6,9 @@ const EXPECTED_COLUMNS: Record<PierType, number> = { 'T형': 1, '2주형': 2, '3
 /** Rules from spec §10 that are not implemented in this stage. Shown to the user, never silently skipped. */
 export const NOT_IMPLEMENTED_RULES = [
   'E04 fck 미입력 (배근 단계, 3단계)',
-  'W03 받침 중심 ~ 계단 경계 < 블럭 폭/2',
-  'W04 블럭이 코핑 평면 밖',
   'W06 속성 복사 건너뜀 (2단계)',
   'W08 솔플레이트 T1−T2 검사 (2단계)',
-  '다주형 코핑 헌치·Level−300 (Q3), 일체기초 판정 (2·3주형)',
+  '일체기초 판정 (2·3주형)',
 ] as const;
 
 /** Input-level checks (spec §10 E01, E02). Returns false when the pier must not be built. */
@@ -34,7 +32,7 @@ export function validateInput(input: PierInput, issues: Issue[]): boolean {
   return ok;
 }
 
-/** Geometry-level checks (spec §10 W01, W02, W05, W07, I01) on a built model. */
+/** Geometry-level checks (spec §10 W01–W05, W07, I01) on a built model. */
 export function validatePier(input: PierInput, model: PierModel, issues: Issue[]): void {
   const ip2Gap = Math.hypot(model.ip2Input.e - model.ip2Calc.e, model.ip2Input.n - model.ip2Calc.n);
   if (ip2Gap > 0.001) {
@@ -49,6 +47,32 @@ export function validatePier(input: PierInput, model: PierModel, issues: Issue[]
   if (minBlock <= 0) {
     issues.push({ code: 'W02', level: 'W', pier: input.name, message: '받침블럭 콘크리트 높이가 0 이하입니다. 블럭을 생략합니다.' });
   }
+  // W03: bearing centre closer than half a block width to a step boundary (interior boundaries only).
+  const halfBlock = DIM.blockSize / 2;
+  const stepBounds = model.segments.slice(1).map((seg) => seg.s0);
+  for (const b of model.bearings) {
+    const nearest = Math.min(...stepBounds.map((s) => Math.abs(b.s - s)));
+    if (nearest < halfBlock) {
+      issues.push({
+        code: 'W03',
+        level: 'W',
+        pier: input.name,
+        message: `${b.row} 받침 ${b.no}번 중심이 계단 경계에서 ${(nearest * 1000).toFixed(0)} mm 떨어져 블럭 폭의 절반(${(halfBlock * 1000).toFixed(0)} mm)보다 가깝습니다.`,
+      });
+    }
+  }
+  // W04: block footprint extends beyond the coping plan (s in [0, L], n in [−B/2, B/2]).
+  const planHalfB = model.copingB / 2;
+  const outside = model.blocks.some(
+    (b) =>
+      b.s - halfBlock < 0 ||
+      b.s + halfBlock > model.copingL ||
+      b.n - halfBlock < -planHalfB ||
+      b.n + halfBlock > planHalfB,
+  );
+  if (outside) {
+    issues.push({ code: 'W04', level: 'W', pier: input.name, message: '받침블럭이 코핑 평면 밖으로 나갑니다.' });
+  }
   if (input.foundationType !== '현장타설말뚝' && model.footings.some((f) => f.top > input.groundEl)) {
     issues.push({ code: 'W05', level: 'W', pier: input.name, message: '확대기초 상면이 지반고보다 높습니다.' });
   }