diff --git a/M02_MasterTemplete/M02_MasterTemplete_TreePanel.ts b/M02_MasterTemplete/M02_MasterTemplete_TreePanel.ts
index 4fa07239..9a27f130 100644
--- a/M02_MasterTemplete/M02_MasterTemplete_TreePanel.ts
+++ b/M02_MasterTemplete/M02_MasterTemplete_TreePanel.ts
@@ -36,6 +36,7 @@ import {
   type TreeView,
 } from "./M02_MasterTemplete_Api_Fetch";
 import { askFolder, askNewItem, askText } from "./M02_MasterTemplete_TreePanel_Dialogs";
+import { attachTreeDrag } from "./M02_MasterTemplete_TreePanel_Drag";
 import {
   clipOf,
   keepClip,
@@ -286,49 +287,18 @@ export function createTreePanel(opt: TreePanelOptions): TreePanelHandle {
       },
       { capture: true },
     );
-    // 끌어다 옮기기(30-2) — 쓸 수 있는 층만 · 고른 것 안의 줄을 끌면 고른 것 전부
-    if (opt.canEdit) {
-      button.draggable = true;
-      button.addEventListener("dragstart", (event) => {
-        const own = targets.get(one.id);
-        dragging = picked.size > 1 && picked.has(one.id) ? pickedTargets() : own ? [own] : null;
-        event.dataTransfer?.setData("text/plain", one.id);
-        if (event.dataTransfer) event.dataTransfer.effectAllowed = "move";
-      });
-      button.addEventListener("dragend", () => {
-        dragging = null;
-        dropMark(null);
-      });
-    }
+    if (opt.canEdit) drag.arm(button, one.id); // 끌어다 옮기기(30-2) — 쓸 수 있는 층만
     return button;
   };
 
-  /* --- 끌어다 놓기: 폴더 줄 위 = 그 안 · 빈 자리 = 맨 위 · 제 안으로는 안 됨 --- */
-  let dragging: Target[] | null = null;
-  const dropDest = (event: DragEvent): string[] | null => {
-    const row = (event.target as HTMLElement).closest<HTMLElement>("[data-node]");
-    const target = row ? targets.get(row.dataset.node ?? "") : undefined;
-    const dest = !row ? [] : target?.kind === "folder" ? target.path : null;
-    const blocked = dragging?.some((t) => t.kind === "folder" && dest && isUnder(dest, t.path));
-    return dest && !blocked ? dest : null;
-  };
-  const dropMark = (row: HTMLElement | null): void => {
-    body.querySelectorAll(".is-drop").forEach((b) => b.classList.remove("is-drop"));
-    row?.classList.add("is-drop");
-  };
-  body.addEventListener("dragover", (event) => {
-    if (!dragging || !dropDest(event)) return;
-    event.preventDefault();
-    dropMark((event.target as HTMLElement).closest<HTMLElement>("[data-node]") ?? body);
-  });
-  body.addEventListener("drop", (event) => {
-    const dest = dragging && dropDest(event);
-    const list = dragging;
-    dragging = null;
-    dropMark(null);
-    if (!dest || !list) return;
-    event.preventDefault();
-    void dropMove(list, dest);
+  const drag = attachTreeDrag({
+    body,
+    targetOf: (id) => targets.get(id),
+    listFor: (id) => {
+      const own = targets.get(id);
+      return picked.size > 1 && picked.has(id) ? pickedTargets() : own ? [own] : null;
+    },
+    move: (list, dest) => void dropMove(list, dest),
   });
 
   /** 놓은 자리로 옮김 — 이미 그 자리인 것은 뺌 · 하나면 한 개 옮기기 · 여럿이면 한 번에 */
diff --git a/M02_MasterTemplete/M02_MasterTemplete_TreePanel_Drag.ts b/M02_MasterTemplete/M02_MasterTemplete_TreePanel_Drag.ts
new file mode 100644
index 00000000..67e137d2
--- /dev/null
+++ b/M02_MasterTemplete/M02_MasterTemplete_TreePanel_Drag.ts
@@ -0,0 +1,74 @@
+/* =============================================================================
+ * M02_MasterTemplete_TreePanel_Drag.ts
+ * 공용 나무 끌어다 옮기기(PLAN 30-2 · 31-5) — 같은 층 안 · 폴더 줄 위 = 그 안 · 빈 자리 = 맨 위 ·
+ * 제 안으로는 안 됨 · 고른 것 안의 줄을 끌면 고른 것 전부. 옮기는 일은 부르는 쪽(`move`).
+ * 놓을 자리 강조는 한 곳만 · 놓음 · 끝 · 칸 밖으로 나감에서 모두 지움(나무 칸 자신 포함).
+ * ========================================================================== */
+
+import type { Target } from "./M02_MasterTemplete_TreePanel_Pick";
+import { isUnder } from "./M02_MasterTemplete_TreePanel_Model";
+
+export interface TreeDragOptions {
+  /** 나무 칸(줄들의 부모 · 빈 자리 = 맨 위) */
+  body: HTMLElement;
+  targetOf: (id: string) => Target | undefined;
+  /** 이 줄을 끌 때 옮길 것 — 고른 것 안이면 고른 것 전부 */
+  listFor: (id: string) => Target[] | null;
+  move: (list: Target[], dest: string[]) => void;
+}
+
+/** 칸에 놓기를 달고 줄마다 끌기를 다는 손잡이(`arm`)를 돌려줌 */
+export function attachTreeDrag(opt: TreeDragOptions): {
+  arm: (row: HTMLElement, id: string) => void;
+} {
+  const { body } = opt;
+  let dragging: Target[] | null = null;
+
+  const dropDest = (event: DragEvent): string[] | null => {
+    const row = (event.target as HTMLElement).closest<HTMLElement>("[data-node]");
+    const target = row ? opt.targetOf(row.dataset.node ?? "") : undefined;
+    const dest = !row ? [] : target?.kind === "folder" ? target.path : null;
+    const blocked = dragging?.some((t) => t.kind === "folder" && dest && isUnder(dest, t.path));
+    return dest && !blocked ? dest : null;
+  };
+  /** 놓을 자리 강조 — 한 곳만 · null = 모두 지움(나무 칸 자신 = 맨 위 자리 포함 · PLAN 31-5 흠) */
+  const dropMark = (row: HTMLElement | null): void => {
+    body.classList.remove("is-drop");
+    body.querySelectorAll(".is-drop").forEach((b) => b.classList.remove("is-drop"));
+    row?.classList.add("is-drop");
+  };
+  // 나무 칸 밖으로 나가면 강조를 지움 — 칸 안 자식 위로 옮겨 갈 때는 그대로(깜빡임 막음)
+  body.addEventListener("dragleave", (event) => {
+    const to = event.relatedTarget as Node | null;
+    if (!to || !body.contains(to)) dropMark(null);
+  });
+  body.addEventListener("dragover", (event) => {
+    if (!dragging || !dropDest(event)) return;
+    event.preventDefault();
+    dropMark((event.target as HTMLElement).closest<HTMLElement>("[data-node]") ?? body);
+  });
+  body.addEventListener("drop", (event) => {
+    const dest = dragging && dropDest(event);
+    const list = dragging;
+    dragging = null;
+    dropMark(null);
+    if (!dest || !list) return;
+    event.preventDefault();
+    opt.move(list, dest);
+  });
+
+  return {
+    arm: (row, id) => {
+      row.draggable = true;
+      row.addEventListener("dragstart", (event) => {
+        dragging = opt.listFor(id);
+        event.dataTransfer?.setData("text/plain", id);
+        if (event.dataTransfer) event.dataTransfer.effectAllowed = "move";
+      });
+      row.addEventListener("dragend", () => {
+        dragging = null;
+        dropMark(null);
+      });
+    },
+  };
+}
diff --git a/M02_MasterTemplete/M02_MasterTemplete_UI_Side.ts b/M02_MasterTemplete/M02_MasterTemplete_UI_Side.ts
index d60cb45a..9c64b6b1 100644
--- a/M02_MasterTemplete/M02_MasterTemplete_UI_Side.ts
+++ b/M02_MasterTemplete/M02_MasterTemplete_UI_Side.ts
@@ -188,6 +188,8 @@ export function buildSide(opt: SideOptions): SideHandle {
     ],
   });
   attachCollapsible(listHost);
+  // 들어오면 「일위대가 조합」 · 「구조물 조합」 둘 다 펼친 채(PLAN 31-5 · 구조물 조합은 위에서 펼침)
+  labor?.body.closest("section")?.classList.remove("is-collapsed");
 
   const root = el("div", { className: "m02-side ui-sidebar-panel", children: [listHost] });
 
diff --git a/resources/tester/test_m02_layer_screen.py b/resources/tester/test_m02_layer_screen.py
index 233719bf..c7bb3f17 100644
--- a/resources/tester/test_m02_layer_screen.py
+++ b/resources/tester/test_m02_layer_screen.py
@@ -231,8 +231,9 @@ def test_켜진_층_단추는_목록으로_복사_끌기():
     labor = _text(M02 / "M02_MasterTemplete_Labor.ts")
     assert 'if (editor.isDirty() && !(await showConfirmDialog(tc("BackAsk")))) return;' in labor
     panel = _text(M02 / "M02_MasterTemplete_TreePanel.ts")
-    assert "if (opt.canEdit) {\n      button.draggable = true;" in panel
-    assert 'dragging?.some((t) => t.kind === "folder" && dest && isUnder(dest, t.path))' in panel
+    assert "if (opt.canEdit) drag.arm(button, one.id);" in panel
+    drag = _text(M02 / "M02_MasterTemplete_TreePanel_Drag.ts")
+    assert 'dragging?.some((t) => t.kind === "folder" && dest && isUnder(dest, t.path))' in drag
 
 
 def test_구조물_조합_제목_줄_새_항목():
@@ -255,3 +256,15 @@ def test_구조물_조합_제목_줄_새_항목():
     assert ".m02-main__new {\n  margin-left: auto;" in _text(
         M02 / "M02_MasterTemplete_UI_Style.css"
     )
+
+
+def test_들어오면_두_컨테이너_펼침_끌기_뒤_강조_지움():
+    """31-5 — 좌측 「일위대가 조합」 · 「구조물 조합」 둘 다 펼친 채 · 끌어 놓은 뒤 강조(나무 칸
+    자신 = 맨 위 자리 포함)를 모두 지움 · 칸 밖으로 나가면 지움(칸 안 자식 위로는 그대로)."""
+    side = _text(M02 / "M02_MasterTemplete_UI_Side.ts")
+    assert 'labor?.body.closest("section")?.classList.remove("is-collapsed");' in side
+    assert 'summary.classList.remove("is-collapsed");' in side
+    drag = _text(M02 / "M02_MasterTemplete_TreePanel_Drag.ts")
+    mark = drag.split("const dropMark = ")[1].split("};")[0]
+    assert 'body.classList.remove("is-drop");' in mark
+    assert "if (!to || !body.contains(to)) dropMark(null);" in drag