From 9c6cabe911e3ccbb578e2ee5b1c7306bcbdae16a Mon Sep 17 00:00:00 2001
From: ysCha <yscha@interplug.co.kr>
Date: Mon, 29 Jun 2026 13:09:06 +0900
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Co-Authored-By: Claude Opus 4 <noreply@anthropic.com>
---
 src/hooks/usePolygon.js | 75 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/src/hooks/usePolygon.js b/src/hooks/usePolygon.js
index 7582a390..87769390 100644
--- a/src/hooks/usePolygon.js
+++ b/src/hooks/usePolygon.js
@@ -1664,6 +1664,81 @@ export const usePolygon = () => {
       }
     }
 
+    // [INNER-TJUNCTION-SPLIT 2026-06-29] 내부선(추녀 hip / 용마루 ridge)의 끝점이 다른 내부선의 몸통(strict
+    //   interior)에 닿는 T-접합인데 그 내부선에 노드가 없으면, getPath 가 그 지점에서 꺾지 못해 한쪽 면이
+    //   통째로 누락된다. (A/B TYPE 박공→처마: ridge x=747(64.2→266.4) 의 내부 (747,236.4) 에 hip
+    //   (662.3,236.4)→(747,236.4) 끝점이 닿는데 ridge 가 안 잘려 우측 6각형 면이 안 생김 — GETSPLIT-IO 진단.)
+    //   MOVED-DIVIDER 는 auxiliaryLine 끝점만, 외곽 split 루프는 외곽선만 자른다 → inner-inner T-접합은 둘 다 미커버.
+    //   여기서 다른 내부선 끝점 위치에서 내부선을 split(노드 삽입)만 한다. merge 없음 — 정상 평면분할 노드를 추가만 하므로
+    //   기존에 닫히던 면은 불변(노드가 명시될 뿐).
+    {
+      const isInnerT = (l) => l.name === 'hip' || l.name === 'ridge'
+      const EPS_T = 2
+      const mkSegT = (proto, sp, ep) => ({
+        name: proto.name,
+        lineName: proto.lineName,
+        attributes: { ...proto.attributes },
+        startPoint: { x: sp.x, y: sp.y },
+        endPoint: { x: ep.x, y: ep.y },
+        x1: sp.x,
+        y1: sp.y,
+        x2: ep.x,
+        y2: ep.y,
+      })
+      const onBodyStrictT = (L, P) => {
+        const ax = L.startPoint.x
+        const ay = L.startPoint.y
+        const dx = L.endPoint.x - ax
+        const dy = L.endPoint.y - ay
+        const lenSq = dx * dx + dy * dy
+        if (lenSq < 1) return false
+        const t = ((P.x - ax) * dx + (P.y - ay) * dy) / lenSq
+        if (t <= 0.03 || t >= 0.97) return false
+        const px = ax + t * dx
+        const py = ay + t * dy
+        return (P.x - px) ** 2 + (P.y - py) ** 2 < EPS_T * EPS_T
+      }
+      const innerLinesT = allLines.filter(isInnerT)
+      if (innerLinesT.length > 1) {
+        const innerPts = []
+        innerLinesT.forEach((l) => {
+          innerPts.push(l.startPoint, l.endPoint)
+        })
+        let didTSplit = false
+        const afterT = []
+        allLines.forEach((L) => {
+          if (!isInnerT(L)) {
+            afterT.push(L)
+            return
+          }
+          const ax = L.startPoint.x
+          const ay = L.startPoint.y
+          const dx = L.endPoint.x - ax
+          const dy = L.endPoint.y - ay
+          const lenSq = dx * dx + dy * dy || 1
+          const tOf = (P) => ((P.x - ax) * dx + (P.y - ay) * dy) / lenSq
+          const cuts = [...new Map(innerPts.filter((P) => onBodyStrictT(L, P)).map((P) => [Math.round(tOf(P) * 1000), P])).values()].sort(
+            (p, q) => tOf(p) - tOf(q),
+          )
+          if (cuts.length === 0) {
+            afterT.push(L)
+            return
+          }
+          didTSplit = true
+          let cur = L.startPoint
+          cuts.forEach((P) => {
+            afterT.push(mkSegT(L, cur, P))
+            cur = P
+          })
+          afterT.push(mkSegT(L, cur, L.endPoint))
+        })
+        if (didTSplit) {
+          logger.log(`[INNER-TJUNCTION-SPLIT] inner-inner T-접합 노드 삽입 (allLines ${allLines.length}→${afterT.length})`)
+          allLines = afterT
+        }
+      }
+    }
+
     // 나눠서 중복 제거된 roof return
     let newRoofs = getSplitRoofsPoints(allLines)