diff --git a/B07_DesignDetail/B07_DesignDetail_Engine_Frame_Export.py b/B07_DesignDetail/B07_DesignDetail_Engine_Frame_Export.py
index e95c3b958..da64d98ee 100644
--- a/B07_DesignDetail/B07_DesignDetail_Engine_Frame_Export.py
+++ b/B07_DesignDetail/B07_DesignDetail_Engine_Frame_Export.py
@@ -195,6 +195,9 @@ def _add_entity(
         start_angle = shape.get("startAngle")
         end_angle = shape.get("endAngle")
         if isinstance(start_angle, (int, float)) and isinstance(end_angle, (int, float)):
+            # DXF 호는 늘 반시계 — 시계방향 호는 시작 · 끝을 바꿔야 같은 작은 호.
+            if shape.get("counterClockwise") is False:
+                start_angle, end_angle = end_angle, start_angle
             space.add_arc(
                 center,
                 radius,
diff --git a/B07_DesignDetail/openwebcad/src/entities/ArcEntity.test.ts b/B07_DesignDetail/openwebcad/src/entities/ArcEntity.test.ts
index c094d88b7..75114f281 100644
--- a/B07_DesignDetail/openwebcad/src/entities/ArcEntity.test.ts
+++ b/B07_DesignDetail/openwebcad/src/entities/ArcEntity.test.ts
@@ -1,7 +1,10 @@
 import { type Arc, Point } from '@flatten-js/core';
 import { describe, expect, it } from 'vitest';
 import { EPSILON } from '../App.consts.ts';
+import type { DrawController } from '../drawControllers/DrawController.ts';
+import { mirrorPointOverAxis } from '../helpers/mirror-point-over-axis.ts';
 import { ArcEntity } from './ArcEntity.ts';
+import { LineEntity } from './LineEntity.ts';
 
 describe('ArcEntity.distanceTo', () => {
 	/**
@@ -57,3 +60,62 @@ describe('ArcEntity.distanceTo', () => {
 		expect(distanceInfo[0]).toBeLessThan(1);
 	});
 });
+
+describe('ArcEntity 대칭 · 그리기 · 복제(84-3)', () => {
+	const middle = (entity: ArcEntity) => {
+		const arc = entity.getShape() as Arc;
+		return arc.pointAtLength(arc.length / 2) as Point;
+	};
+	const mirrorOver = (axisEnd: Point) => {
+		const arc = new ArcEntity('layer1', new Point(2, 1), 1, 0, Math.PI / 2, true);
+		const before = arc.getShape() as Arc;
+		const axis = new LineEntity('layer1', new Point(0, 0), axisEnd);
+		const expected = [before.start, middle(arc), before.end].map((point) =>
+			mirrorPointOverAxis(point, axis)
+		);
+		arc.mirror(axis);
+		const after = arc.getShape() as Arc;
+		return { expected, actual: [after.start, middle(arc), after.end], length: after.length };
+	};
+
+	for (const [name, axisEnd] of [
+		['세로축', new Point(0, 1)],
+		['가로축', new Point(1, 0)],
+		['45° 축', new Point(1, 1)],
+		['30° 축', new Point(Math.cos(Math.PI / 6), Math.sin(Math.PI / 6))],
+	] as const) {
+		it(`${name} 대칭 — 끝점 · 가운데 점이 대칭 자리 · 작은 호 그대로`, () => {
+			const { expected, actual, length } = mirrorOver(axisEnd);
+			for (let index = 0; index < 3; index++) {
+				expect(actual[index].x).toBeCloseTo(expected[index].x, 9);
+				expect(actual[index].y).toBeCloseTo(expected[index].y, 9);
+			}
+			expect(length).toBeCloseTo(Math.PI / 2, 9);
+		});
+	}
+
+	it('시작각이 음수 · 끝각 0 인 호 — 끝각을 2π 로 바꾸지 않음(온 원으로 안 그림)', () => {
+		const arc = new ArcEntity('layer1', new Point(0, 0), 1, -Math.PI / 2, 0, true);
+		const calls: number[][] = [];
+		const controller = {
+			setLineStyles: () => {},
+			drawArc: (_c: Point, _r: number, start: number, end: number) => calls.push([start, end]),
+		} as unknown as DrawController;
+		arc.draw(controller);
+		expect(calls[0][1] - calls[0][0]).toBeCloseTo(Math.PI / 2, 9);
+	});
+
+	it('복제 — 색 · 층 · 선 꼴 그대로', () => {
+		const arc = new ArcEntity('구조물', new Point(0, 0), 1, 0, 1, false);
+		arc.lineColor = '#ff0000';
+		arc.lineWidth = 3;
+		arc.lineDash = [2, 1];
+		const copy = arc.clone();
+		expect([copy.layerId, copy.lineColor, copy.lineWidth, copy.lineDash]).toEqual([
+			'구조물',
+			'#ff0000',
+			3,
+			[2, 1],
+		]);
+	});
+});
diff --git a/B07_DesignDetail/openwebcad/src/entities/ArcEntity.ts b/B07_DesignDetail/openwebcad/src/entities/ArcEntity.ts
index f5e9e49c8..43b522328 100644
--- a/B07_DesignDetail/openwebcad/src/entities/ArcEntity.ts
+++ b/B07_DesignDetail/openwebcad/src/entities/ArcEntity.ts
@@ -60,8 +60,9 @@ export class ArcEntity implements Entity, StartAndEndpointEntity {
 		drawController.drawArc(
 			this.arc.center,
 			this.arc.r.valueOf(),
-			this.arc?.startAngle || 0,
-			this.arc?.endAngle || 2 * Math.PI,
+			this.arc.startAngle,
+			// 끝각 = 시작각 ± 쓸어간 각 — 끝각 0 을 2π 로 바꾸면 시작각이 음수인 호(대칭 뒤)가 온 원으로 그려짐.
+			this.arc.startAngle + (this.arc.counterClockwise ? this.arc.sweep : -this.arc.sweep),
 			this.arc.counterClockwise
 		);
 	}
@@ -87,12 +88,13 @@ export class ArcEntity implements Entity, StartAndEndpointEntity {
 
 	public mirror(mirrorAxis: LineEntity) {
 		const mirroredCenter = mirrorPointOverAxis(this.arc.center, mirrorAxis);
-		mirrorAxis.getAngle();
+		// 축 각 θ 에 대한 대칭 — 각 α → 2θ − α · 도는 방향 반대.
+		const doubleAxisAngle = 2 * mirrorAxis.getAngle();
 		this.arc = new Arc(
 			mirroredCenter,
 			this.arc.r.valueOf(),
-			-this.arc.startAngle,
-			-this.arc.endAngle,
+			doubleAxisAngle - this.arc.startAngle,
+			doubleAxisAngle - this.arc.endAngle,
 			!this.arc.counterClockwise
 		);
 	}
@@ -100,14 +102,13 @@ export class ArcEntity implements Entity, StartAndEndpointEntity {
 	public clone(): Entity {
 		if (this.arc) {
 			const { center, r, startAngle, endAngle, counterClockwise } = this.arc;
-			return new ArcEntity(
-				getActiveLayerId(),
-				center,
-				r.valueOf(),
-				startAngle,
-				endAngle,
-				counterClockwise
-			);
+			// 색 · 층 · 선 꼴은 그대로 — 폴리선 자식도 이 길로 복제됨.
+			const copy = new ArcEntity(this.layerId, center, r.valueOf(), startAngle, endAngle, counterClockwise);
+			copy.lineColor = this.lineColor;
+			copy.lineWidth = this.lineWidth;
+			copy.lineDash = this.lineDash;
+			copy.opacity = this.opacity;
+			return copy;
 		}
 		return this;
 	}
diff --git a/B07_DesignDetail/openwebcad/src/entities/LineEntity.ts b/B07_DesignDetail/openwebcad/src/entities/LineEntity.ts
index 590a5d1bf..bed94b431 100644
--- a/B07_DesignDetail/openwebcad/src/entities/LineEntity.ts
+++ b/B07_DesignDetail/openwebcad/src/entities/LineEntity.ts
@@ -76,7 +76,13 @@ export class LineEntity implements Entity, StartAndEndpointEntity {
 	}
 
 	public clone(): LineEntity {
-		return new LineEntity(getActiveLayerId(), this.segment.clone());
+		// 색 · 층 · 선 꼴은 그대로 — 폴리선 자식도 이 길로 복제됨.
+		const copy = new LineEntity(this.layerId, this.segment.clone());
+		copy.lineColor = this.lineColor;
+		copy.lineWidth = this.lineWidth;
+		copy.lineDash = this.lineDash;
+		copy.opacity = this.opacity;
+		return copy;
 	}
 
 	public intersectsWithBox(box: Box): boolean {
diff --git a/B07_DesignDetail/openwebcad/src/tools/array-tool.ts b/B07_DesignDetail/openwebcad/src/tools/array-tool.ts
index 829a3454a..2fd83edff 100644
--- a/B07_DesignDetail/openwebcad/src/tools/array-tool.ts
+++ b/B07_DesignDetail/openwebcad/src/tools/array-tool.ts
@@ -16,6 +16,7 @@ import {
 } from '../state';
 import { Tool } from '../tools';
 import { CopyAction } from './copy-tool.ts';
+import { cloneKeepingLook } from './move-tool.helpers.ts';
 import { selectToolStateMachine } from './select-tool.ts';
 import type {
 	AbsolutePointInputEvent,
@@ -337,7 +338,7 @@ export const arrayToolStateMachine = createMachine(
 						const y = distanceVector.y * i;
 						resultEntities.push(
 							...getSelectedEntities().map((entity) => {
-								const clone = entity.clone();
+								const clone = cloneKeepingLook(entity);
 								clone.move(x, y);
 								return clone;
 							})
@@ -346,7 +347,7 @@ export const arrayToolStateMachine = createMachine(
 						const angleRad = context.angleStep * i * TO_RADIANS;
 						resultEntities.push(
 							...getSelectedEntities().map((entity) => {
-								const clone = entity.clone();
+								const clone = cloneKeepingLook(entity);
 								clone.rotate(context.pivotPoint as Point, angleRad);
 								return clone;
 							})
diff --git a/B07_DesignDetail/openwebcad/src/tools/copy-tool.ts b/B07_DesignDetail/openwebcad/src/tools/copy-tool.ts
index 7ef246f2f..73b6811fb 100644
--- a/B07_DesignDetail/openwebcad/src/tools/copy-tool.ts
+++ b/B07_DesignDetail/openwebcad/src/tools/copy-tool.ts
@@ -17,7 +17,7 @@ import type { Entity } from '../entities/Entity';
 import { compact } from 'es-toolkit';
 import { LineEntity } from '../entities/LineEntity';
 import { GUIDE_LINE_COLOR, GUIDE_LINE_STYLE, GUIDE_LINE_WIDTH } from '../App.consts';
-import { moveEntities } from './move-tool.helpers';
+import { cloneKeepingLook, moveEntities } from './move-tool.helpers';
 
 export interface CopyContext extends ToolContext {
 	startPoint: Point | null;
@@ -208,7 +208,7 @@ export const copyToolStateMachine = createMachine(
 				return {
 					startPoint: context.startPoint,
 					// Make a copy of the selected entities before copying them, so we can restore them when the user cancels the copy action
-					originalSelectedEntities: compact(selectedEntities.map((entity) => entity.clone())),
+					originalSelectedEntities: compact(selectedEntities.map((entity) => cloneKeepingLook(entity))),
 					copiedEntities: selectedEntities,
 				};
 			}),
@@ -221,7 +221,7 @@ export const copyToolStateMachine = createMachine(
 
 				// Copy the entities to the new location
 				// Draw all selected entities according to translation vector, so the user gets visual feedback of where the entities will be copied;
-				const movedEntities = context.originalSelectedEntities.map((entity) => entity.clone());
+				const movedEntities = context.originalSelectedEntities.map((entity) => cloneKeepingLook(entity));
 				moveEntities(
 					movedEntities,
 					endPointTemp.x - context.startPoint.x,
@@ -246,15 +246,15 @@ export const copyToolStateMachine = createMachine(
 
 				// Copy the entities one final time
 				const currentEndPoint = (event as MouseClickEvent).worldMouseLocation;
-				const copiedEntities = context.originalSelectedEntities.map((entity) => entity.clone());
+				const copiedEntities = context.originalSelectedEntities.map((entity) => cloneKeepingLook(entity));
 				moveEntities(
 					copiedEntities,
 					currentEndPoint.x - context.startPoint.x,
 					currentEndPoint.y - context.startPoint.y
 				);
 
-				// Switch the copied entities back from the ghost helper entities to the real entities
-				addEntities([...context.originalSelectedEntities, ...copiedEntities], true);
+				// 원본은 목록에 그대로 있음 — 복사본만 더함(원본까지 더하면 누를 때마다 원본이 겹겹이 쌓임).
+				addEntities(copiedEntities, true);
 			},
 			[CopyAction.DESELECT_ENTITIES]: assign(() => {
 				setGhostHelperEntities([]);
diff --git a/B07_DesignDetail/openwebcad/src/tools/move-tool.helpers.ts b/B07_DesignDetail/openwebcad/src/tools/move-tool.helpers.ts
index 97c15c503..c05b9451c 100644
--- a/B07_DesignDetail/openwebcad/src/tools/move-tool.helpers.ts
+++ b/B07_DesignDetail/openwebcad/src/tools/move-tool.helpers.ts
@@ -1,4 +1,5 @@
 import type { Entity } from '../entities/Entity';
+import { copyStyle } from './modify/modify.helpers';
 
 /**
  * Move entities by the difference between the start and end points
@@ -11,3 +12,17 @@ export function moveEntities(entities: Entity[], deltaX: number, deltaY: number)
 		entity.move(deltaX, deltaY);
 	}
 }
+
+/**
+ * 복제해도 색 · 층 · 선 꼴 · 투명도를 그대로 둔다(`clone()` 은 활성 층 · 흰색으로 새로 만듦).
+ * `inPlace` = 옮기기 · 크기 · 회전처럼 같은 도형을 갈아 끼울 때 — id · 묶음까지 그대로.
+ */
+export function cloneKeepingLook(entity: Entity, inPlace = false): Entity {
+	const copy = copyStyle(entity, entity.clone());
+	copy.opacity = entity.opacity;
+	if (inPlace) {
+		copy.id = entity.id;
+		copy.groupId = entity.groupId;
+	}
+	return copy;
+}
diff --git a/B07_DesignDetail/openwebcad/src/tools/move-tool.ts b/B07_DesignDetail/openwebcad/src/tools/move-tool.ts
index 346be9091..ba19c7073 100644
--- a/B07_DesignDetail/openwebcad/src/tools/move-tool.ts
+++ b/B07_DesignDetail/openwebcad/src/tools/move-tool.ts
@@ -16,7 +16,7 @@ import { assign, createMachine, sendTo } from 'xstate';
 import { selectToolStateMachine } from './select-tool';
 import type { Entity } from '../entities/Entity';
 import { compact } from 'es-toolkit';
-import { moveEntities } from './move-tool.helpers';
+import { cloneKeepingLook, moveEntities } from './move-tool.helpers';
 import { LineEntity } from '../entities/LineEntity';
 import { GUIDE_LINE_COLOR, GUIDE_LINE_STYLE, GUIDE_LINE_WIDTH } from '../App.consts';
 
@@ -211,7 +211,7 @@ export const moveToolStateMachine = createMachine(
 				return {
 					startPoint: context.startPoint,
 					// Make a copy of the selected entities before moving them, so we can restore them when the user cancels the move action
-					originalSelectedEntities: compact(selectedEntities.map((entity) => entity.clone())),
+					originalSelectedEntities: compact(selectedEntities.map((entity) => cloneKeepingLook(entity, true))),
 					movedEntities: selectedEntities,
 				};
 			}),
@@ -224,7 +224,7 @@ export const moveToolStateMachine = createMachine(
 
 				// Move the entities to the new location
 				// Draw all selected entities according to translation vector, so the user gets visual feedback of where the entities will be moved;
-				const movedEntities = context.originalSelectedEntities.map((entity) => entity.clone());
+				const movedEntities = context.originalSelectedEntities.map((entity) => cloneKeepingLook(entity, true));
 				moveEntities(
 					movedEntities,
 					endPointTemp.x - context.startPoint.x,
diff --git a/B07_DesignDetail/openwebcad/src/tools/rotate-tool.ts b/B07_DesignDetail/openwebcad/src/tools/rotate-tool.ts
index 0d792a54e..46888d7a5 100644
--- a/B07_DesignDetail/openwebcad/src/tools/rotate-tool.ts
+++ b/B07_DesignDetail/openwebcad/src/tools/rotate-tool.ts
@@ -16,6 +16,7 @@ import { selectToolStateMachine } from './select-tool';
 import type { Entity } from '../entities/Entity';
 import { compact } from 'es-toolkit';
 import { rotateEntities } from './rotate-tool.helpers';
+import { cloneKeepingLook } from './move-tool.helpers';
 
 export interface RotateContext extends ToolContext {
 	rotationOrigin: Point | null;
@@ -231,7 +232,7 @@ export const rotateToolStateMachine = createMachine(
 				return {
 					...context,
 					// Make a copy of the selected entities before rotating them, so we can restore them when the user cancels the rotate action
-					originalSelectedEntities: compact(selectedEntities.map((entity) => entity.clone())),
+					originalSelectedEntities: compact(selectedEntities.map((entity) => cloneKeepingLook(entity, true))),
 				};
 			}),
 			[RotateAction.DRAW_TEMP_ROTATE_ENTITIES]: ({ context, event }) => {
@@ -245,7 +246,7 @@ export const rotateToolStateMachine = createMachine(
 
 				// Draw all selected entities according to rotate vector, so the user gets visual feedback of where the entities will be end up after rotating
 				const rotatedEntities = compact(
-					context.originalSelectedEntities.map((entity) => entity.clone())
+					context.originalSelectedEntities.map((entity) => cloneKeepingLook(entity, true))
 				);
 				rotateEntities(
 					rotatedEntities,
@@ -264,7 +265,7 @@ export const rotateToolStateMachine = createMachine(
 
 				// Rotate the entities one final time
 				const rotatedEntities = compact(
-					context.originalSelectedEntities.map((entity) => entity.clone())
+					context.originalSelectedEntities.map((entity) => cloneKeepingLook(entity, true))
 				);
 				rotateEntities(
 					rotatedEntities,
diff --git a/B07_DesignDetail/openwebcad/src/tools/scale-tool.ts b/B07_DesignDetail/openwebcad/src/tools/scale-tool.ts
index 99b5ed11c..660a885b2 100644
--- a/B07_DesignDetail/openwebcad/src/tools/scale-tool.ts
+++ b/B07_DesignDetail/openwebcad/src/tools/scale-tool.ts
@@ -16,6 +16,7 @@ import { selectToolStateMachine } from './select-tool';
 import type { Entity } from '../entities/Entity';
 import { compact } from 'es-toolkit';
 import { scaleEntities } from './scale-tool.helpers';
+import { cloneKeepingLook } from './move-tool.helpers';
 
 export interface ScaleContext extends ToolContext {
 	baseVectorStartPoint: Point | null;
@@ -234,7 +235,7 @@ export const scaleToolStateMachine = createMachine(
 				return {
 					...context,
 					// Make a copy of the selected entities before scaling them, so we can restore them when the user cancels the scale action
-					originalSelectedEntities: compact(selectedEntities.map((entity) => entity.clone())),
+					originalSelectedEntities: compact(selectedEntities.map((entity) => cloneKeepingLook(entity, true))),
 				};
 			}),
 			[ScaleAction.DRAW_TEMP_SCALE_ENTITIES]: ({ context, event }) => {
@@ -248,7 +249,7 @@ export const scaleToolStateMachine = createMachine(
 
 				// Draw all selected entities according to scale vector, so the user gets visual feedback of where the entities will be end up after scaling
 				const scaledEntities = compact(
-					context.originalSelectedEntities.map((entity) => entity.clone())
+					context.originalSelectedEntities.map((entity) => cloneKeepingLook(entity, true))
 				);
 				scaleEntities(
 					scaledEntities,
@@ -267,7 +268,7 @@ export const scaleToolStateMachine = createMachine(
 
 				// Scale the entities one final time
 				const scaledEntities = compact(
-					context.originalSelectedEntities.map((entity) => entity.clone())
+					context.originalSelectedEntities.map((entity) => cloneKeepingLook(entity, true))
 				);
 				scaleEntities(
 					scaledEntities,
diff --git a/resources/tester/cad/clone-keeps-look.test.ts b/resources/tester/cad/clone-keeps-look.test.ts
new file mode 100644
index 000000000..bb39eeb68
--- /dev/null
+++ b/resources/tester/cad/clone-keeps-look.test.ts
@@ -0,0 +1,61 @@
+/**
+ * 옮기기 · 크기 · 회전 · 복사 · 배열 복제가 색 · 층 · 선 꼴을 지키는지(84-3).
+ * 실행: cd B07_DesignDetail/openwebcad && npx vitest run --config <include 를 이 파일로 바꾼 vitest.tmp.config.ts>
+ */
+import { Point } from "@flatten-js/core";
+import { describe, expect, it } from "vitest";
+import { LineEntity } from "../../../B07_DesignDetail/openwebcad/src/entities/LineEntity";
+import { PointEntity } from "../../../B07_DesignDetail/openwebcad/src/entities/PointEntity";
+import { PolyLineEntity } from "../../../B07_DesignDetail/openwebcad/src/entities/PolyLineEntity";
+import { TextEntity } from "../../../B07_DesignDetail/openwebcad/src/entities/TextEntity";
+import { cloneKeepingLook } from "../../../B07_DesignDetail/openwebcad/src/tools/move-tool.helpers";
+import type { Entity } from "../../../B07_DesignDetail/openwebcad/src/entities/Entity";
+
+const styled = <T extends Entity>(entity: T): T => {
+  entity.lineColor = "#ff0000";
+  entity.lineWidth = 2;
+  entity.lineDash = [4, 2];
+  entity.opacity = 0.5;
+  entity.groupId = "g1";
+  return entity;
+};
+const look = (entity: Entity) => [
+  entity.layerId,
+  entity.lineColor,
+  entity.lineWidth,
+  entity.lineDash,
+  entity.opacity,
+];
+const LOOK = ["구조물", "#ff0000", 2, [4, 2], 0.5];
+
+describe("cloneKeepingLook", () => {
+  const samples: [string, () => Entity][] = [
+    ["선", () => styled(new LineEntity("구조물", new Point(0, 0), new Point(1, 0)))],
+    ["점", () => styled(new PointEntity("구조물", new Point(1, 1)))],
+    ["글", () => styled(new TextEntity("구조물", "배수관", new Point(0, 0)))],
+  ];
+  for (const [name, make] of samples) {
+    it(`${name} — 옮기기(inPlace) 는 id · 묶음 · 색 · 층 그대로`, () => {
+      const source = make();
+      const copy = cloneKeepingLook(source, true);
+      copy.move(5, 5);
+      expect(look(copy)).toEqual(LOOK);
+      expect([copy.id, copy.groupId]).toEqual([source.id, "g1"]);
+    });
+    it(`${name} — 복사는 새 id · 색 · 층 그대로`, () => {
+      const source = make();
+      const copy = cloneKeepingLook(source);
+      expect(look(copy)).toEqual(LOOK);
+      expect(copy.id).not.toBe(source.id);
+    });
+  }
+
+  it("폴리선 — 자식 선까지 색 · 층 그대로(크기 바꿈 뒤)", () => {
+    const child = styled(new LineEntity("구조물", new Point(0, 0), new Point(1, 0)));
+    const polyline = styled(new PolyLineEntity("구조물", [child]));
+    const copy = cloneKeepingLook(polyline, true) as PolyLineEntity;
+    copy.scale(new Point(0, 0), 2);
+    expect(look(copy)).toEqual(LOOK);
+    expect(look(copy.getEntities()[0])).toEqual(LOOK);
+  });
+});