From 00a379595b0c5e3299f08165967731725b457f5d Mon Sep 17 00:00:00 2001
From: umsangdon <umsangdon@gmail.com>
Date: Fri, 16 Oct 2026 00:14:29 +0900
Subject: [PATCH] =?UTF-8?q?feat(CAD):=20337-4a=20=EB=8B=A4-1=20=EA=B3=A0?=
 =?UTF-8?q?=EC=B9=98=EA=B8=B0=207=20=E2=80=94=20OFFSET=20=C2=B7=20FILLET?=
 =?UTF-8?q?=20=C2=B7=20CHAMFER=20=C2=B7=20TRIM=20=C2=B7=20EXTEND=20=C2=B7?=
 =?UTF-8?q?=20BREAK=20=C2=B7=20JOIN=20=EC=98=A4=ED=86=A0=EC=BA=90=EB=93=9C?=
 =?UTF-8?q?=20=EB=AC=BC=EC=9D=8C=20=EC=B0=A8=EB=A1=80=20=C2=B7=20=EC=98=B5?=
 =?UTF-8?q?=EC=85=98=20=C2=B7=20=EA=B8=B0=EB=B3=B8=EA=B0=92=20=EA=B8=B0?=
 =?UTF-8?q?=EC=96=B5=20=C2=B7=20=EB=B9=88=20Enter=20=C2=B7=20Esc=20=C2=B7?=
 =?UTF-8?q?=20=EB=81=9D=EB=82=9C=20=EB=92=A4?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- OFFSET 새 파일(offset-tool.ts) — 거리 <통과점> · 통과점(T) · 지우기(E) 예/아니오 · 객체 → 면의 점 되풀이 · 다중(M) <다음 객체> · 명령 취소(U) · 기억 OFFSETDIST · OFFSETERASE
- FILLET · CHAMFER 한 꼴 — 객체 먼저 · 반지름(R) · 거리(D) 둘(둘째 기본 = 첫째) · 자르기(T) 모드 · 다중(M) · 명령 취소(U) · Shift = 구석 · 기억 FILLETRAD · CHAMFERA/B · TRIMMODE
- TRIM · EXTEND 빠른 모드 한 꼴 — 되풀이 · Shift = 반대 일 · 집기 반경 밖 무시 · 지우기(R) · 숨은 U · 사각형 변 원래 층 · 꼴(N9) · 자른 선 꼴 유지
- BREAK — 누른 점 = 첫 끊기점 · 첫 번째 점(F) · @0,0 = 같은 점 · JOIN 물음 글
- 시험 resources/tester/cad/modify-acad.test.ts 13

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013QyNXY2TUKXCFMwAca2APG
---
 .../src/commands/commands.modify.ts           |   2 +-
 .../src/tools/eraser-tool.helpers.ts          |  65 ++-
 .../openwebcad/src/tools/eraser-tool.ts       | 243 +++++++---
 .../src/tools/modify/corner-tools.ts          | 420 ++++++++++++++++--
 .../src/tools/modify/offset-tool.ts           | 219 +++++++++
 .../src/tools/modify/structure-tools.ts       |  34 +-
 resources/tester/cad/modify-acad.test.ts      | 374 ++++++++++++++++
 7 files changed, 1216 insertions(+), 141 deletions(-)
 create mode 100644 B07_DesignDetail/openwebcad/src/tools/modify/offset-tool.ts
 create mode 100644 resources/tester/cad/modify-acad.test.ts

diff --git a/B07_DesignDetail/openwebcad/src/commands/commands.modify.ts b/B07_DesignDetail/openwebcad/src/commands/commands.modify.ts
index 14e078a66..1efeadeaf 100644
--- a/B07_DesignDetail/openwebcad/src/commands/commands.modify.ts
+++ b/B07_DesignDetail/openwebcad/src/commands/commands.modify.ts
@@ -32,11 +32,11 @@ import {
 	extendToolStateMachine,
 	joinToolStateMachine,
 } from '../tools/modify/structure-tools';
+import { offsetToolStateMachine } from '../tools/modify/offset-tool';
 import {
 	alignToolStateMachine,
 	lengthenToolStateMachine,
 	mirrorToolStateMachine,
-	offsetToolStateMachine,
 	stretchToolStateMachine,
 } from '../tools/modify/transform-tools';
 import { moveToolStateMachine } from '../tools/move-tool';
diff --git a/B07_DesignDetail/openwebcad/src/tools/eraser-tool.helpers.ts b/B07_DesignDetail/openwebcad/src/tools/eraser-tool.helpers.ts
index 9238c284c..50475a2a9 100644
--- a/B07_DesignDetail/openwebcad/src/tools/eraser-tool.helpers.ts
+++ b/B07_DesignDetail/openwebcad/src/tools/eraser-tool.helpers.ts
@@ -1,15 +1,68 @@
-import { type Circle, Point, type Segment } from '@flatten-js/core';
+import { type Circle, Point, Segment } from '@flatten-js/core';
 import { compact } from 'es-toolkit';
 import { ArcEntity } from '../entities/ArcEntity';
 import type { CircleEntity } from '../entities/CircleEntity';
 import type { Entity } from '../entities/Entity';
-import type { LineEntity } from '../entities/LineEntity';
+import { LineEntity } from '../entities/LineEntity';
+import { findClosestEntity } from '../helpers/find-closest-entity';
 import { findNeighboringPointsOnArc } from '../helpers/find-neighboring-points-on-arc';
 import { findNeighboringPointsOnCircle } from '../helpers/find-neighboring-points-on-circle';
 import { findNeighboringPointsOnLine } from '../helpers/find-neighboring-points-on-line';
+import { sampleEntityPoints } from '../helpers/geometry/sample-entity';
+import { intersectLines } from '../helpers/geometry/shape-points';
 import { getAngleWithXAxis } from '../helpers/get-angle-with-x-axis.ts';
 import { isPointEqual } from '../helpers/is-point-equal';
-import { addEntities, deleteEntities, getActiveLayerId } from '../state';
+import { pickRadius } from '../helpers/pick-radius';
+import { queryEntitiesNearPoint } from '../helpers/spatial-index';
+import { addEntities, deleteEntities, getActiveLayerId, getLayerById } from '../state';
+import { copyStyle, isBetween } from './modify/modify.helpers';
+
+/** 누른 자리 집기 반경 안 가장 가까운 객체 — 잠금 도면층 뺌(순서 엔진과 같은 셈) */
+export function pickEntityAt(point: Point): Entity | null {
+	const radius = pickRadius();
+	const candidates = queryEntitiesNearPoint(point.x, point.y, radius).filter(
+		(entity) => !getLayerById(entity.layerId)?.isLocked
+	);
+	const { distance, entity } = findClosestEntity(point, candidates);
+	return entity && distance <= radius ? entity : null;
+}
+
+/** 점을 객체 위로 내림(가장 가까운 자리) */
+export const closestPointOn = (entity: Entity, point: Point): Point =>
+	findClosestEntity(point, [entity]).segment?.start ?? point;
+
+/** EXTEND 빠른 모드 — 누른 쪽 끝을 그 방향 가장 가까운 경계(다른 모든 객체)까지 · 선만 */
+export function extendLineEnd(line: Entity, pick: Point, boundaries: Entity[]): Entity | null {
+	const shape = line.getShape();
+	if (!(shape instanceof Segment)) return null;
+	const fromStart = pick.distanceTo(shape.start)[0] < pick.distanceTo(shape.end)[0];
+	const tip = fromStart ? shape.start : shape.end;
+	const tail = fromStart ? shape.end : shape.start;
+	const length = tail.distanceTo(tip)[0];
+	if (!length) return null;
+	const dx = (tip.x - tail.x) / length;
+	const dy = (tip.y - tail.y) / length;
+	let best = Number.POSITIVE_INFINITY;
+	let hit: Point | null = null;
+	for (const boundary of boundaries) {
+		if (boundary.id === line.id) continue;
+		const points = sampleEntityPoints(boundary);
+		for (let index = 1; index < points.length; index++) {
+			const crossing = intersectLines(tail, tip, points[index - 1], points[index]);
+			if (!crossing || !isBetween(crossing, points[index - 1], points[index])) continue;
+			const ahead = (crossing.x - tip.x) * dx + (crossing.y - tip.y) * dy;
+			if (ahead > 1e-9 && ahead < best) {
+				best = ahead;
+				hit = crossing;
+			}
+		}
+	}
+	if (!hit) return null;
+	return copyStyle(
+		line,
+		new LineEntity(line.layerId, fromStart ? hit : tail, fromStart ? tail : hit)
+	);
+}
 
 export function getAllIntersectionPoints(entity: Entity, entities: Entity[]): Point[] {
 	// TODO see if we need to make this list unique
@@ -39,8 +92,10 @@ export function eraseLineSegment(
 	);
 
 	const cutLines: Entity[] = line.cutAtPoints([firstCutPoint, secondCutPoint]);
-	// Remove the segment that has the clickedPointOnShape point on it
-	const remainingLines = cutLines.filter((line) => !line.containsPointOnShape(clickedPointOnShape));
+	// Remove the segment that has the clickedPointOnShape point on it — 남는 토막은 원래 층 · 꼴(N9)
+	const remainingLines = cutLines
+		.filter((piece) => !piece.containsPointOnShape(clickedPointOnShape))
+		.map((piece) => copyStyle(line, piece));
 	deleteEntities([line], false);
 
 	// Helper functions should never trigger an undo state, since they can be called multiple times during one user operation
diff --git a/B07_DesignDetail/openwebcad/src/tools/eraser-tool.ts b/B07_DesignDetail/openwebcad/src/tools/eraser-tool.ts
index 933a54d2e..ca2746b20 100644
--- a/B07_DesignDetail/openwebcad/src/tools/eraser-tool.ts
+++ b/B07_DesignDetail/openwebcad/src/tools/eraser-tool.ts
@@ -1,100 +1,91 @@
+/**
+ * TRIM · EXTEND 빠른 모드(337 설계 1-2) — 누를 때마다 자름(연장) · Shift+누름 = 반대 일 · 되풀이 ·
+ * 빈 Enter · Esc = 끝 · 집기 반경 밖 누름은 아무 일 없음(N9) · U = 이 명령 안 마지막 하나 ·
+ * TRIM 지우기(R) = 고르기 → Enter 로 지우고 돌아옴.
+ */
 import type { Point, Polygon } from '@flatten-js/core';
-import { assign, createMachine } from 'xstate';
+import { assign, createMachine, sendTo } from 'xstate';
+import {
+	OPT,
+	type OptionSpec,
+	type PromptSpec,
+	SELECT_OBJECTS,
+	rememberSelection,
+} from '../commands/prompt';
 import type { ArcEntity } from '../entities/ArcEntity';
 import type { CircleEntity } from '../entities/CircleEntity';
 import { EntityName } from '../entities/Entity';
 import { LineEntity } from '../entities/LineEntity';
 import type { RectangleEntity } from '../entities/RectangleEntity';
 import { findClosestEntity } from '../helpers/find-closest-entity';
+import { pickRadius } from '../helpers/pick-radius';
 import { polygonToSegments } from '../helpers/polygon-to-segments';
 import {
 	addEntities,
 	deleteEntities,
-	getActiveLayerId,
 	getEntities,
 	getPickableEntities,
+	getSelectedEntities,
 	setEntities,
 	setGhostHelperEntities,
+	setSelectedEntityIds,
 	setShouldDrawHelpers,
+	undo,
 } from '../state';
 import { Tool } from '../tools';
 import {
 	eraseArcSegment,
 	eraseCircleSegment,
 	eraseLineSegment,
+	extendLineEnd,
 	getAllIntersectionPoints,
+	pickEntityAt,
 } from './eraser-tool.helpers';
-import type { MouseClickEvent, StateEvent, ToolContext } from './tool.types';
+import { copyStyle } from './modify/modify.helpers';
+import { selectToolStateMachine } from './select-tool';
+import { END_STATE, type MouseClickEvent, type StateEvent, type ToolContext } from './tool.types';
 
 export interface EraserContext extends ToolContext {
-	startPoint: Point | null;
+	/** 이 명령에서 바꾼 횟수(U) */
+	made: number;
 }
 
 export enum EraserState {
 	INIT = 'INIT',
 	WAITING_FOR_FIRST_CLICK = 'WAITING_FOR_FIRST_CLICK',
+	ERASE_PICK = 'ERASE_PICK',
 }
 
-export enum EraserAction {
-	INIT_ERASER_TOOL = 'INIT_ERASER_TOOL',
-	HANDLE_MOUSE_CLICK = 'HANDLE_MOUSE_CLICK',
-}
+const absent = (key: string, kw: string, label: string): OptionSpec => ({
+	key,
+	kw,
+	en: key,
+	label,
+});
+const HIDDEN_UNDO: OptionSpec = { ...OPT.UNDO, hidden: true };
+const CROSSING = absent('CROSSING', 'C', '걸치기');
+const MODE = absent('MODE', 'O', '모드');
+const PROJECT = absent('PROJECT', 'P', '투영');
 
-export const eraserToolStateMachine = createMachine(
-	{
-		types: {} as {
-			context: EraserContext;
-			events: StateEvent;
-		},
-		context: {
-			startPoint: null,
-			type: Tool.ERASER,
-		},
-		initial: EraserState.INIT,
-		states: {
-			[EraserState.INIT]: {
-				description: 'Initializing the eraser tool',
-				always: {
-					actions: EraserAction.INIT_ERASER_TOOL,
-					target: EraserState.WAITING_FOR_FIRST_CLICK,
-				},
-			},
-			[EraserState.WAITING_FOR_FIRST_CLICK]: {
-				description: '지울 선 선택',
-				meta: {
-					instructions: '지울 선 선택',
-				},
-				on: {
-					// TODO implement a DRAW action to draw the segment that will be erased in dotted line
-					MOUSE_CLICK: {
-						actions: EraserAction.HANDLE_MOUSE_CLICK,
-						target: EraserState.WAITING_FOR_FIRST_CLICK,
-					},
-				},
-			},
-			// TODO implement rectangle selection to delete
-		},
-	},
-	{
-		actions: {
-			[EraserAction.INIT_ERASER_TOOL]: assign(() => {
-				setShouldDrawHelpers(false);
-				setGhostHelperEntities([]);
-				return {};
-			}),
-			[EraserAction.HANDLE_MOUSE_CLICK]: assign(({ context, event }) => {
-				handleMouseClick((event as MouseClickEvent).worldMouseLocation);
+const TRIM_PROMPT: PromptSpec = {
+	text: '자를 객체 선택 또는 Shift 키를 누른 채 선택하여 연장',
+	options: [{ key: 'ERASE', kw: 'R', en: 'ERASE', label: '지우기' }, HIDDEN_UNDO],
+	absent: [absent('CUTTINGEDGES', 'T', '절단 모서리'), CROSSING, MODE, PROJECT],
+};
+const EXTEND_PROMPT: PromptSpec = {
+	text: '연장할 객체 선택 또는 Shift 키를 누른 채 선택하여 자르기',
+	options: [HIDDEN_UNDO],
+	absent: [absent('BOUNDARYEDGES', 'B', '경계 모서리'), CROSSING, MODE, PROJECT],
+};
 
-				return context;
-			}),
-		},
-	}
-);
-
-export function handleMouseClick(worldMouseLocation: Point) {
+/** TRIM 한 번 — 누른 자리 반경 안 객체만(없으면 false) · 사각형 변은 원래 층 · 꼴 */
+export function handleMouseClick(
+	worldMouseLocation: Point,
+	radius = Number.POSITIVE_INFINITY
+): boolean {
 	const closestEntity = findClosestEntity(worldMouseLocation, getPickableEntities());
-	if (!closestEntity) {
-		return;
+	if (!closestEntity.entity || closestEntity.distance > radius) {
+		return false;
 	}
 
 	const clickedPointOnShape = closestEntity.segment.start;
@@ -125,8 +116,8 @@ export function handleMouseClick(worldMouseLocation: Point) {
 		case EntityName.Rectangle: {
 			const rectangle = closestEntity.entity as RectangleEntity;
 			const segments = polygonToSegments(rectangle.getShape() as Polygon);
-			const segmentEntities = segments.map(
-				(segment) => new LineEntity(getActiveLayerId(), segment)
+			const segmentEntities = segments.map((segment) =>
+				copyStyle(rectangle, new LineEntity(rectangle.layerId, segment))
 			);
 
 			// Find the closest segment to the clicked point
@@ -151,11 +142,129 @@ export function handleMouseClick(worldMouseLocation: Point) {
 			break;
 		}
 
-		case EntityName.Image: {
-			// TODO implement image eraser
-			// Switch to rectangle entity and delete the image and the line that was closest to the cursor
-		}
+		default:
+			return false;
 	}
 
 	setEntities(getEntities(), true); // Force a new undo state entry
+	return true;
 }
+
+/** EXTEND 한 번 — 누른 쪽 끝을 가장 가까운 경계까지 · 못 늘리면 false */
+export function extendAt(worldMouseLocation: Point): boolean {
+	const target = pickEntityAt(worldMouseLocation);
+	if (!target) return false;
+	const extended = extendLineEnd(target, worldMouseLocation, getPickableEntities());
+	if (!extended) return false;
+	deleteEntities([target], false);
+	addEntities([extended], true);
+	return true;
+}
+
+const trimAt = (location: Point) => handleMouseClick(location, pickRadius());
+
+type Ctx = { context: EraserContext; event: StateEvent };
+
+/** 빠른 자르기 · 연장 머신 — `act(점, shift)` 가 바꿨으면 true */
+function createQuickEditTool(
+	tool: Tool,
+	prompt: PromptSpec,
+	act: (location: Point, shift: boolean) => boolean
+) {
+	const undoLast = assign(({ context }: Ctx) => {
+		if (context.made === 0) return {};
+		undo();
+		return { made: context.made - 1 };
+	});
+	const end = { target: END_STATE };
+	const forward = { actions: sendTo('trimErase', ({ event }: Ctx) => event) };
+	const takesErase = prompt.options?.some((option) => option.key === 'ERASE');
+
+	return createMachine(
+		{
+			types: {} as { context: EraserContext; events: StateEvent },
+			context: { made: 0, type: tool },
+			initial: EraserState.INIT,
+			// biome-ignore lint/suspicious/noExplicitAny: 상태마다 사건 꼴이 달라 느슨하게(순서 엔진과 같음)
+			states: <Record<string, any>>{
+				[EraserState.INIT]: {
+					always: {
+						actions: () => {
+							setShouldDrawHelpers(false);
+							setGhostHelperEntities([]);
+						},
+						target: EraserState.WAITING_FOR_FIRST_CLICK,
+					},
+				},
+				[EraserState.WAITING_FOR_FIRST_CLICK]: {
+					meta: { kind: 'entity', prompt },
+					on: {
+						MOUSE_CLICK: {
+							actions: assign(({ context, event }: Ctx) => {
+								const click = event as MouseClickEvent;
+								return act(click.worldMouseLocation, !!click.holdingShift)
+									? { made: context.made + 1 }
+									: {};
+							}),
+						},
+						...(takesErase ? { 'OPTION.ERASE': { target: EraserState.ERASE_PICK } } : {}),
+						'OPTION.UNDO': { actions: undoLast },
+						ENTER: end,
+						ESC: end,
+					},
+				},
+				...(takesErase
+					? {
+							[EraserState.ERASE_PICK]: {
+								meta: {
+									kind: 'selection',
+									prompt: { text: '지울 객체 선택', options: SELECT_OBJECTS.options },
+								},
+								entry: () => setShouldDrawHelpers(false),
+								invoke: {
+									id: 'trimErase',
+									src: selectToolStateMachine,
+									onDone: {
+										actions: assign(({ context }: Ctx) => {
+											const picked = getSelectedEntities();
+											if (!picked.length) return {};
+											rememberSelection(picked.map((entity) => entity.id));
+											setSelectedEntityIds([]);
+											deleteEntities(picked, true);
+											return { made: context.made + 1 };
+										}),
+										target: EraserState.WAITING_FOR_FIRST_CLICK,
+									},
+								},
+								on: {
+									MOUSE_CLICK: forward,
+									ENTER: forward,
+									DRAW: forward,
+									'OPTION.*': forward,
+									ESC: { actions: () => setSelectedEntityIds([]), target: END_STATE },
+								},
+							},
+						}
+					: {}),
+				[END_STATE]: { type: 'final' },
+			},
+		},
+		{
+			// 고르기 자식(선택 도구)의 액션 구현을 함께 넘긴다
+			// biome-ignore lint/suspicious/noExplicitAny: 자식 머신의 컨텍스트 타입이 달라 그대로 넘긴다
+			actions: { ...(selectToolStateMachine.implementations.actions as any) },
+		}
+	);
+}
+
+export const eraserToolStateMachine = createQuickEditTool(
+	Tool.ERASER,
+	TRIM_PROMPT,
+	(location, shift) => (shift ? extendAt(location) : trimAt(location))
+);
+
+export const extendToolStateMachine = createQuickEditTool(
+	Tool.EXTEND,
+	EXTEND_PROMPT,
+	(location, shift) => (shift ? trimAt(location) : extendAt(location))
+);
diff --git a/B07_DesignDetail/openwebcad/src/tools/modify/corner-tools.ts b/B07_DesignDetail/openwebcad/src/tools/modify/corner-tools.ts
index 425b352a4..d971a1ea6 100644
--- a/B07_DesignDetail/openwebcad/src/tools/modify/corner-tools.ts
+++ b/B07_DesignDetail/openwebcad/src/tools/modify/corner-tools.ts
@@ -1,57 +1,290 @@
-/** 모깎기·모따기·곡선 혼합·끊기 (조사표 2절) */
+/**
+ * 모깎기·모따기·곡선 혼합·끊기 (조사표 2절 · 337 설계 1-2)
+ * FILLET · CHAMFER = 오토캐드 차례 — 첫 객체(또는 U · R/D · T · M) → 둘째 객체(Shift = 구석) · 값 · 자르기 모드 기억 ·
+ * 다중이면 쌍 되풀이 · 빈 Enter · Esc = 끝. BREAK = 누른 점이 첫 끊기점 · F = 첫 점 다시 · `@0,0` = 같은 점.
+ */
+import type { Point } from '@flatten-js/core';
 import { toast } from 'react-toastify';
+import { assign, createMachine } from 'xstate';
+import { OPT, type OptionSpec, type PromptSpec, recall, remember } from '../../commands/prompt';
 import type { Entity } from '../../entities/Entity';
-import { addEntities, deleteEntities } from '../../state';
+import { getPointFromEvent } from '../../helpers/get-point-from-event';
+import {
+	addEntities,
+	deleteEntities,
+	getEntities,
+	setAngleGuideOriginPoint,
+	setGhostHelperEntities,
+	setShouldDrawHelpers,
+	undo,
+} from '../../state';
 import { Tool } from '../../tools';
+import { closestPointOn, pickEntityAt } from '../eraser-tool.helpers';
 import { createSequenceTool } from '../factories/sequence-tool';
+import {
+	END_STATE,
+	type MouseClickEvent,
+	type PointInputEvent,
+	type StateEvent,
+	type ToolContext,
+} from '../tool.types';
 import { blendEntities, breakEntity, chamferLines, filletLines } from './corner.helpers';
 import type { CornerResult } from './corner.helpers';
 
-function applyCorner(first: Entity, second: Entity, result: CornerResult | null): void {
+const option = (key: string, kw: string, label: string): OptionSpec => ({
+	key,
+	kw,
+	en: key,
+	label,
+});
+const entityById = (id: string | null): Entity | undefined =>
+	getEntities().find((entity) => entity.id === id);
+
+// ---- FILLET · CHAMFER ----
+
+interface CornerContext extends ToolContext {
+	firstId: string | null;
+	firstPick: Point | null;
+	multiple: boolean;
+	/** 이 명령에서 만든 쌍 수(U) */
+	made: number;
+	/** 값 · 자르기 물음 뒤 돌아갈 물음 */
+	back: 'FIRST' | 'SECOND';
+	/** 방금 누른 쌍을 처리했는가 */
+	ok: boolean;
+}
+
+interface CornerSpec {
+	tool: Tool;
+	first: string;
+	second: string;
+	/** 반지름(R) · 거리(D) */
+	value: OptionSpec;
+	absentFirst: OptionSpec[];
+	absentSecond: OptionSpec[];
+	/** 값 물음 차례 — shown = 그 열쇠 값을 <기본> 으로 보임 */
+	values: Array<{ text: string; remember: string; shown?: string }>;
+	/** corner = Shift+누름(반지름 · 거리 0) */
+	apply(
+		first: Entity,
+		firstPick: Point,
+		second: Entity,
+		secondPick: Point,
+		corner: boolean
+	): CornerResult | null;
+}
+
+const TRIM_OPTION = option('TRIM', 'T', '자르기');
+const POLYLINE = option('POLYLINE', 'P', '폴리선');
+const TRIM_MODE_PROMPT = (): PromptSpec => ({
+	text: '자르기 모드 옵션 입력',
+	options: [TRIM_OPTION, option('NOTRIM', 'N', '자르지 않기')],
+	default: { kind: 'option', key: recall<string>('TRIMMODE') ?? 'TRIM' },
+});
+
+type CornerCtx = { context: CornerContext; event: StateEvent };
+
+function applyPair(spec: CornerSpec, context: CornerContext, click: MouseClickEvent): boolean {
+	const first = entityById(context.firstId);
+	const second = pickEntityAt(click.worldMouseLocation);
+	if (!first || !second || !context.firstPick) return false;
+	const result = spec.apply(
+		first,
+		context.firstPick,
+		second,
+		click.worldMouseLocation,
+		!!click.holdingShift
+	);
 	if (!result) {
 		toast.warn('두 직선을 선택해야 합니다. 두 선이 평행하면 처리할 수 없습니다.');
-		return;
+		return false;
+	}
+	if (recall('TRIMMODE') === 'NOTRIM') {
+		if (!result.corner) return false;
+		addEntities([result.corner], true);
+		return true;
 	}
 	deleteEntities([first, second], false);
 	addEntities([...result.trimmed, ...(result.corner ? [result.corner] : [])], true);
+	return true;
 }
 
-export const filletToolStateMachine = createSequenceTool({
+function createCornerTool(spec: CornerSpec) {
+	const end = { target: END_STATE };
+	const back = [
+		{ guard: ({ context }: CornerCtx) => context.back === 'SECOND', target: 'SECOND' },
+		{ target: 'FIRST' },
+	];
+	// 값 물음 — 마지막 값 뒤 = 돌아갈 물음
+	const valueStates = Object.fromEntries(
+		spec.values.map((value, index) => {
+			const store = {
+				actions: ({ event }: CornerCtx) =>
+					remember(value.remember, (event as { value: number }).value),
+			};
+			const isLast = index === spec.values.length - 1;
+			return [
+				`VALUE_${index}`,
+				{
+					meta: {
+						kind: 'number',
+						prompt: {
+							text: value.text,
+							default: { kind: 'value', remember: value.shown ?? value.remember, initial: 0 },
+							number: { min: 0 },
+						} satisfies PromptSpec,
+					},
+					on: {
+						NUMBER_INPUT: isLast
+							? back.map((transition) => ({ ...transition, ...store }))
+							: { ...store, target: `VALUE_${index + 1}` },
+						ESC: end,
+					},
+				},
+			];
+		})
+	);
+
+	return createMachine({
+		types: {} as { context: CornerContext; events: StateEvent },
+		context: {
+			firstId: null,
+			firstPick: null,
+			multiple: false,
+			made: 0,
+			back: 'FIRST',
+			ok: false,
+			type: spec.tool,
+		},
+		initial: 'INIT',
+		// biome-ignore lint/suspicious/noExplicitAny: 상태마다 사건 꼴이 달라 느슨하게(순서 엔진과 같음)
+		states: <Record<string, any>>{
+			INIT: {
+				always: {
+					actions: () => {
+						setShouldDrawHelpers(false);
+						setGhostHelperEntities([]);
+					},
+					target: 'FIRST',
+				},
+			},
+			FIRST: {
+				meta: {
+					kind: 'entity',
+					prompt: {
+						text: spec.first,
+						options: [OPT.UNDO, spec.value, TRIM_OPTION, OPT.MULTIPLE],
+						absent: spec.absentFirst,
+					} satisfies PromptSpec,
+				},
+				on: {
+					MOUSE_CLICK: {
+						guard: ({ event }: CornerCtx) =>
+							!!pickEntityAt((event as MouseClickEvent).worldMouseLocation),
+						actions: assign(({ event }: CornerCtx) => {
+							const location = (event as MouseClickEvent).worldMouseLocation;
+							return { firstId: pickEntityAt(location)?.id ?? null, firstPick: location };
+						}),
+						target: 'SECOND',
+					},
+					[`OPTION.${spec.value.key}`]: {
+						actions: assign({ back: 'FIRST' as const }),
+						target: 'VALUE_0',
+					},
+					'OPTION.TRIM': { target: 'TRIM_MODE' },
+					'OPTION.MULTIPLE': { actions: assign({ multiple: true }) },
+					'OPTION.UNDO': {
+						actions: assign(({ context }: CornerCtx) => {
+							if (context.made === 0) return {};
+							undo();
+							return { made: context.made - 1 };
+						}),
+					},
+					ENTER: end,
+					ESC: end,
+				},
+			},
+			SECOND: {
+				meta: {
+					kind: 'entity',
+					prompt: {
+						text: spec.second,
+						options: [spec.value],
+						absent: spec.absentSecond,
+					} satisfies PromptSpec,
+				},
+				on: {
+					MOUSE_CLICK: {
+						actions: assign(({ context, event }: CornerCtx) => {
+							const ok = applyPair(spec, context, event as MouseClickEvent);
+							return { ok, made: context.made + (ok ? 1 : 0) };
+						}),
+						target: 'APPLIED',
+					},
+					[`OPTION.${spec.value.key}`]: {
+						actions: assign({ back: 'SECOND' as const }),
+						target: 'VALUE_0',
+					},
+					ENTER: end,
+					ESC: end,
+				},
+			},
+			APPLIED: {
+				always: [
+					{ guard: ({ context }: CornerCtx) => !context.ok, target: 'SECOND' },
+					{ guard: ({ context }: CornerCtx) => context.multiple, target: 'FIRST' },
+					{ target: END_STATE },
+				],
+			},
+			TRIM_MODE: {
+				meta: { kind: 'keyword', prompt: TRIM_MODE_PROMPT },
+				on: {
+					'OPTION.TRIM': { actions: () => remember('TRIMMODE', 'TRIM'), target: 'FIRST' },
+					'OPTION.NOTRIM': { actions: () => remember('TRIMMODE', 'NOTRIM'), target: 'FIRST' },
+					ESC: end,
+				},
+			},
+			...valueStates,
+			[END_STATE]: { type: 'final' },
+		},
+	});
+}
+
+const radius = () => recall<number>('FILLETRAD') ?? 0;
+
+export const filletToolStateMachine = createCornerTool({
 	tool: Tool.FILLET,
-	helpers: false,
-	steps: [
-		{ kind: 'number', instructions: '모깎기 반지름을 입력하십시오 <0>.', defaultValue: 0 },
-		{ kind: 'entity', instructions: '첫 번째 객체를 남길 쪽에서 선택하십시오.' },
-		{ kind: 'entity', instructions: '두 번째 객체를 남길 쪽에서 선택하십시오.' },
-	],
-	commit: (input) => {
-		const first = input.entity(1);
-		const second = input.entity(2);
-		applyCorner(
-			first,
-			second,
-			filletLines(first, input.pick(1), second, input.pick(2), input.number(0))
-		);
-	},
+	first: '첫 번째 객체 선택',
+	second: '두 번째 객체 선택 또는 Shift 키를 누른 채 선택하여 구석 적용',
+	value: option('RADIUS', 'R', '반지름'),
+	absentFirst: [POLYLINE],
+	absentSecond: [],
+	values: [{ text: '모깎기 반지름 지정', remember: 'FILLETRAD' }],
+	apply: (first, firstPick, second, secondPick, corner) =>
+		filletLines(first, firstPick, second, secondPick, corner ? 0 : radius()),
 });
 
-export const chamferToolStateMachine = createSequenceTool({
+const ANGLE = option('ANGLE', 'A', '각도');
+const METHOD = option('METHOD', 'E', '방법');
+
+export const chamferToolStateMachine = createCornerTool({
 	tool: Tool.CHAMFER,
-	helpers: false,
-	steps: [
-		{ kind: 'number', instructions: '첫 번째 모따기 거리를 입력하십시오 <1>.', defaultValue: 1 },
-		{ kind: 'number', instructions: '두 번째 모따기 거리를 입력하십시오 <1>.', defaultValue: 1 },
-		{ kind: 'entity', instructions: '첫 번째 객체를 남길 쪽에서 선택하십시오.' },
-		{ kind: 'entity', instructions: '두 번째 객체를 남길 쪽에서 선택하십시오.' },
+	first: '첫 번째 선 선택',
+	second: '두 번째 선 선택 또는 Shift 키를 누른 채 선택하여 구석 적용',
+	value: option('DISTANCE', 'D', '거리'),
+	absentFirst: [POLYLINE, ANGLE, METHOD],
+	absentSecond: [ANGLE, METHOD],
+	values: [
+		{ text: '첫 번째 모따기 거리 지정', remember: 'CHAMFERA' },
+		{ text: '두 번째 모따기 거리 지정', remember: 'CHAMFERB', shown: 'CHAMFERA' },
 	],
-	commit: (input) => {
-		const first = input.entity(2);
-		const second = input.entity(3);
-		applyCorner(
-			first,
-			second,
-			chamferLines(first, input.pick(2), second, input.pick(3), input.number(0), input.number(1))
-		);
+	apply: (first, firstPick, second, secondPick, corner) => {
+		const a = recall<number>('CHAMFERA') ?? 0;
+		const b = recall<number>('CHAMFERB') ?? 0;
+		// 거리 0 · Shift = 구석(모깎기 반지름 0 과 같음)
+		return corner || (a === 0 && b === 0)
+			? filletLines(first, firstPick, second, secondPick, 0)
+			: chamferLines(first, firstPick, second, secondPick, a, b);
 	},
 });
 
@@ -72,18 +305,111 @@ export const blendToolStateMachine = createSequenceTool({
 	},
 });
 
-export const breakToolStateMachine = createSequenceTool({
-	tool: Tool.BREAK,
-	steps: [
-		{ kind: 'entity', instructions: '끊을 객체를 선택하십시오.' },
-		{ kind: 'point', instructions: '첫 번째 끊기 점을 지정하십시오.' },
-		{ kind: 'point', instructions: '두 번째 끊기 점을 지정하십시오.' },
-	],
-	commit: (input) => {
-		const entity = input.entity(0);
-		const pieces = breakEntity(entity, input.point(1), input.point(2));
-		deleteEntities([entity], false);
-		addEntities(pieces, true);
+// ---- BREAK ----
+
+interface BreakContext extends ToolContext {
+	entityId: string | null;
+	first: Point | null;
+}
+
+type BreakCtx = { context: BreakContext; event: StateEvent };
+
+/** 두 끊기점 사이를 지움 · 같은 점 = 틈 없이 둘로 */
+function breakNow(context: BreakContext, event: StateEvent) {
+	const entity = entityById(context.entityId);
+	if (!entity || !context.first) return;
+	const first = closestPointOn(entity, context.first);
+	const second = closestPointOn(entity, getPointFromEvent(context.first, event as PointInputEvent));
+	const same = Math.hypot(first.x - second.x, first.y - second.y) < 1e-9;
+	const pieces = same ? breakEntity(entity, first) : breakEntity(entity, first, second);
+	if (same && pieces.length < 2) return;
+	deleteEntities([entity], false);
+	addEntities(pieces, true);
+}
+
+const POINT_EVENTS = [
+	'MOUSE_CLICK',
+	'ABSOLUTE_POINT_INPUT',
+	'RELATIVE_POINT_INPUT',
+	'NUMBER_INPUT',
+];
+const onPoint = (transition: object) =>
+	Object.fromEntries(POINT_EVENTS.map((type) => [type, transition]));
+const FIRST_POINT = option('FIRST', 'F', '첫 번째 점');
+
+export const breakToolStateMachine = createMachine({
+	types: {} as { context: BreakContext; events: StateEvent },
+	context: { entityId: null, first: null, type: Tool.BREAK },
+	initial: 'INIT',
+	states: {
+		INIT: {
+			always: {
+				actions: () => {
+					setShouldDrawHelpers(false);
+					setGhostHelperEntities([]);
+				},
+				target: 'OBJECT',
+			},
+		},
+		OBJECT: {
+			meta: { kind: 'entity', prompt: { text: '객체 선택' } satisfies PromptSpec },
+			on: {
+				MOUSE_CLICK: {
+					guard: ({ event }: BreakCtx) =>
+						!!pickEntityAt((event as MouseClickEvent).worldMouseLocation),
+					actions: assign(({ event }: BreakCtx) => {
+						const location = (event as MouseClickEvent).worldMouseLocation;
+						const entity = pickEntityAt(location) as Entity;
+						const first = closestPointOn(entity, location);
+						setAngleGuideOriginPoint(first);
+						return { entityId: entity.id, first };
+					}),
+					target: 'SECOND',
+				},
+				ENTER: { target: END_STATE },
+				ESC: { target: END_STATE },
+			},
+		},
+		SECOND: {
+			meta: {
+				kind: 'point',
+				prompt: { text: '두 번째 끊기점 지정', options: [FIRST_POINT] } satisfies PromptSpec,
+			},
+			entry: () => setShouldDrawHelpers(true),
+			on: {
+				...onPoint({
+					actions: ({ context, event }: BreakCtx) => breakNow(context, event),
+					target: END_STATE,
+				}),
+				'OPTION.FIRST': { target: 'FIRST_POINT' },
+				ESC: { target: END_STATE },
+			},
+		},
+		FIRST_POINT: {
+			meta: { kind: 'point', prompt: { text: '첫 번째 끊기점 지정' } satisfies PromptSpec },
+			on: {
+				...onPoint({
+					actions: assign(({ context, event }: BreakCtx) => {
+						const first = getPointFromEvent(context.first, event as PointInputEvent);
+						setAngleGuideOriginPoint(first);
+						return { first };
+					}),
+					target: 'SECOND_POINT',
+				}),
+				ESC: { target: END_STATE },
+			},
+		},
+		SECOND_POINT: {
+			meta: { kind: 'point', prompt: { text: '두 번째 끊기점 지정' } satisfies PromptSpec },
+			on: {
+				...onPoint({
+					actions: ({ context, event }: BreakCtx) => breakNow(context, event),
+					target: END_STATE,
+				}),
+				ESC: { target: END_STATE },
+			},
+		},
+		[END_STATE]: { type: 'final' },
 	},
 });
 
diff --git a/B07_DesignDetail/openwebcad/src/tools/modify/offset-tool.ts b/B07_DesignDetail/openwebcad/src/tools/modify/offset-tool.ts
new file mode 100644
index 000000000..2d2a0d9ae
--- /dev/null
+++ b/B07_DesignDetail/openwebcad/src/tools/modify/offset-tool.ts
@@ -0,0 +1,219 @@
+/**
+ * OFFSET(337 설계 1-2) — 오토캐드 간격띄우기 차례: 거리(또는 통과점(T) · 지우기(E)) → 객체 → 면의 점 →
+ * 객체로 되풀이 · 다중(M) = 방금 만든 것을 같은 거리로 되풀이 · U = 이 명령 안 마지막 하나 · 빈 Enter · Esc = 끝.
+ * 거리 기억 = OFFSETDIST(처음 <통과점>) · 원본 지우기 기억 = OFFSETERASE.
+ */
+import { type Point, Segment } from '@flatten-js/core';
+import { toast } from 'react-toastify';
+import { assign, createMachine } from 'xstate';
+import { OPT, type OptionSpec, type PromptSpec, recall, remember } from '../../commands/prompt';
+import type { Entity } from '../../entities/Entity';
+import { findClosestEntity } from '../../helpers/find-closest-entity';
+import { getPointFromEvent } from '../../helpers/get-point-from-event';
+import {
+	addEntities,
+	deleteEntities,
+	getEntities,
+	setAngleGuideOriginPoint,
+	setGhostHelperEntities,
+	setShouldDrawHelpers,
+	undo,
+} from '../../state';
+import { Tool } from '../../tools';
+import { pickEntityAt } from '../eraser-tool.helpers';
+import {
+	type DrawEvent,
+	END_STATE,
+	type MouseClickEvent,
+	type PointInputEvent,
+	type StateEvent,
+	type ToolContext,
+} from '../tool.types';
+import { offsetEntity } from './modify.helpers';
+
+interface OffsetContext extends ToolContext {
+	/** 간격띄울 객체 */
+	sourceId: string | null;
+	/** 처음 고른 객체 — 원본 지우기는 이것만 */
+	pickedId: string | null;
+	multiple: boolean;
+	/** 이 명령에서 만든 수(U) */
+	made: number;
+}
+
+type Ctx = { context: OffsetContext; event: StateEvent };
+
+const option = (key: string, kw: string, label: string): OptionSpec => ({
+	key,
+	kw,
+	en: key,
+	label,
+});
+const THROUGH = option('THROUGH', 'T', '통과점');
+
+/** 기억한 거리 · null = 통과점 */
+const offsetDistance = (): number | null => {
+	const distance = recall('OFFSETDIST');
+	return typeof distance === 'number' ? distance : null;
+};
+
+const DISTANCE_PROMPT = (): PromptSpec => {
+	const distance = offsetDistance();
+	return {
+		text: '간격띄우기 거리 지정',
+		options: [THROUGH, option('ERASE', 'E', '지우기')],
+		absent: [option('LAYER', 'L', '도면층')],
+		default:
+			distance === null
+				? { kind: 'option', key: 'THROUGH' }
+				: { kind: 'value', remember: 'OFFSETDIST', initial: distance },
+		number: { positive: true },
+	};
+};
+const ERASE_PROMPT = (): PromptSpec => ({
+	text: '간격띄우기 후 원본 객체를 지우시겠습니까?',
+	options: [OPT.YES, OPT.NO],
+	default: { kind: 'option', key: recall('OFFSETERASE') ? 'YES' : 'NO' },
+});
+const OBJECT_PROMPT: PromptSpec = {
+	text: '간격띄우기할 객체 선택',
+	options: [OPT.EXIT, OPT.UNDO],
+	default: { kind: 'enter', label: '종료' },
+};
+const SIDE_PROMPT = (context: Partial<OffsetContext>): PromptSpec => ({
+	text: offsetDistance() === null ? '통과점 지정' : '간격띄우기할 면의 점 지정',
+	options: context.multiple ? [OPT.EXIT, OPT.UNDO] : [OPT.EXIT, OPT.MULTIPLE, OPT.UNDO],
+	default: { kind: 'enter', label: context.multiple ? '다음 객체' : '종료' },
+});
+
+/** 통과점까지 거리 — 선은 무한 직선까지(오토캐드) · 그 밖은 모양까지 */
+function throughDistance(entity: Entity, point: Point): number {
+	const shape = entity.getShape();
+	if (shape instanceof Segment) {
+		const { start, end } = shape;
+		const length = start.distanceTo(end)[0] || 1;
+		return (
+			Math.abs((end.x - start.x) * (point.y - start.y) - (end.y - start.y) * (point.x - start.x)) /
+			length
+		);
+	}
+	return findClosestEntity(point, [entity]).distance;
+}
+
+function offsetThrough(source: Entity, point: Point): Entity | null {
+	return offsetEntity(source, offsetDistance() ?? throughDistance(source, point), point);
+}
+
+const sourceOf = (context: OffsetContext) =>
+	getEntities().find((entity) => entity.id === context.sourceId);
+
+/** 면의 점 하나 → 새 객체 · 다중이면 그것이 다음 원본 */
+const placeOffset = assign(({ context, event }: Ctx): Partial<OffsetContext> => {
+	const source = sourceOf(context);
+	if (!source) return { sourceId: null };
+	const point = getPointFromEvent(null, event as PointInputEvent);
+	const result = offsetThrough(source, point);
+	setGhostHelperEntities([]);
+	if (!result) {
+		toast.warn('이 객체는 지정한 거리로 간격을 띄울 수 없습니다.');
+		return {};
+	}
+	if (recall('OFFSETERASE') && source.id === context.pickedId) deleteEntities([source], false);
+	addEntities([result], true);
+	return { made: context.made + 1, sourceId: context.multiple ? result.id : null };
+});
+
+const undoLast = assign(({ context }: Ctx): Partial<OffsetContext> => {
+	setGhostHelperEntities([]);
+	if (context.made === 0) return {};
+	undo();
+	return { made: context.made - 1, sourceId: null, multiple: false };
+});
+
+const end = { target: END_STATE };
+const toObject = { actions: assign({ sourceId: null, multiple: false }), target: 'OBJECT' };
+
+// biome-ignore lint/suspicious/noExplicitAny: 상태마다 사건 꼴이 달라 느슨하게(순서 엔진과 같음)
+const states: Record<string, any> = {
+	INIT: {
+		always: {
+			actions: () => {
+				setShouldDrawHelpers(false);
+				setGhostHelperEntities([]);
+				setAngleGuideOriginPoint(null);
+			},
+			target: 'DISTANCE',
+		},
+	},
+	DISTANCE: {
+		meta: { kind: 'number', prompt: DISTANCE_PROMPT },
+		on: {
+			NUMBER_INPUT: {
+				actions: ({ event }: Ctx) => remember('OFFSETDIST', (event as { value: number }).value),
+				target: 'OBJECT',
+			},
+			'OPTION.THROUGH': { actions: () => remember('OFFSETDIST', 'THROUGH'), target: 'OBJECT' },
+			'OPTION.ERASE': { target: 'ERASE' },
+			ESC: end,
+		},
+	},
+	ERASE: {
+		meta: { kind: 'keyword', prompt: ERASE_PROMPT },
+		on: {
+			'OPTION.YES': { actions: () => remember('OFFSETERASE', true), target: 'DISTANCE' },
+			'OPTION.NO': { actions: () => remember('OFFSETERASE', false), target: 'DISTANCE' },
+			ESC: end,
+		},
+	},
+	OBJECT: {
+		meta: { kind: 'entity', prompt: OBJECT_PROMPT },
+		entry: () => setShouldDrawHelpers(false),
+		on: {
+			MOUSE_CLICK: {
+				guard: ({ event }: Ctx) => !!pickEntityAt((event as MouseClickEvent).worldMouseLocation),
+				actions: assign(({ event }: Ctx) => {
+					const id = pickEntityAt((event as MouseClickEvent).worldMouseLocation)?.id ?? null;
+					return { sourceId: id, pickedId: id };
+				}),
+				target: 'SIDE',
+			},
+			'OPTION.EXIT': end,
+			'OPTION.UNDO': { actions: undoLast },
+			ENTER: end,
+			ESC: end,
+		},
+	},
+	SIDE: {
+		meta: { kind: 'point', prompt: SIDE_PROMPT },
+		entry: () => setShouldDrawHelpers(true),
+		on: {
+			DRAW: {
+				actions: ({ context, event }: Ctx) => {
+					const source = sourceOf(context);
+					const preview =
+						source && offsetThrough(source, getPointFromEvent(null, event as DrawEvent));
+					setGhostHelperEntities(preview ? [preview] : []);
+				},
+			},
+			MOUSE_CLICK: { actions: placeOffset, target: 'PLACED' },
+			ABSOLUTE_POINT_INPUT: { actions: placeOffset, target: 'PLACED' },
+			'OPTION.EXIT': end,
+			'OPTION.MULTIPLE': { actions: assign({ multiple: true }) },
+			'OPTION.UNDO': { actions: undoLast, target: 'OBJECT' },
+			ENTER: [{ guard: ({ context }: Ctx) => context.multiple, ...toObject }, end],
+			ESC: end,
+		},
+	},
+	/** 다중이면 같은 물음 · 아니면 객체로 */
+	PLACED: {
+		always: [{ guard: ({ context }: Ctx) => !!context.sourceId, target: 'SIDE' }, toObject],
+	},
+	[END_STATE]: { type: 'final' },
+};
+
+export const offsetToolStateMachine = createMachine({
+	types: {} as { context: OffsetContext; events: StateEvent },
+	context: { sourceId: null, pickedId: null, multiple: false, made: 0, type: Tool.OFFSET },
+	initial: 'INIT',
+	states,
+});
diff --git a/B07_DesignDetail/openwebcad/src/tools/modify/structure-tools.ts b/B07_DesignDetail/openwebcad/src/tools/modify/structure-tools.ts
index b49e1bd3f..a5535b388 100644
--- a/B07_DesignDetail/openwebcad/src/tools/modify/structure-tools.ts
+++ b/B07_DesignDetail/openwebcad/src/tools/modify/structure-tools.ts
@@ -1,35 +1,27 @@
 /** 연장·결합·분해·지우기 (조사표 2절) */
 import { toast } from 'react-toastify';
+import { SELECT_OBJECTS } from '../../commands/prompt';
 import type { Entity } from '../../entities/Entity';
 import { addEntities, deleteEntities, setSelectedEntityIds } from '../../state';
 import { Tool } from '../../tools';
 import { createSequenceTool } from '../factories/sequence-tool';
-import { explodeEntity, extendLineToBoundary, joinEntities } from './modify.helpers';
+import { explodeEntity, joinEntities } from './modify.helpers';
 
-export const extendToolStateMachine = createSequenceTool({
-	tool: Tool.EXTEND,
-	helpers: false,
-	steps: [
-		{ kind: 'entity', instructions: '경계로 쓸 객체를 선택하십시오.' },
-		{ kind: 'entity', instructions: '연장할 선을 선택하십시오.' },
-	],
-	commit: (input) => {
-		const boundary = input.entity(0);
-		const target = input.entity(1);
-		const extended = extendLineToBoundary(target, boundary);
-		if (!extended) {
-			toast.warn('경계와 만나도록 연장할 수 없습니다.');
-			return;
-		}
-		deleteEntities([target], false);
-		addEntities([extended], true);
-	},
-});
+/** EXTEND 빠른 모드는 TRIM 과 한 머신 꼴(eraser-tool.ts) */
+export { extendToolStateMachine } from '../eraser-tool';
 
 export const joinToolStateMachine = createSequenceTool({
 	tool: Tool.JOIN,
 	helpers: false,
-	steps: [{ kind: 'selection', instructions: '결합할 객체를 선택한 뒤 ENTER.' }],
+	steps: [
+		{
+			kind: 'selection',
+			prompt: {
+				text: '한 번에 결합할 원본 객체 또는 여러 객체 선택',
+				options: SELECT_OBJECTS.options,
+			},
+		},
+	],
 	commit: (input) => {
 		const entities = input.entities(0);
 		const joined = joinEntities(entities);
diff --git a/resources/tester/cad/modify-acad.test.ts b/resources/tester/cad/modify-acad.test.ts
new file mode 100644
index 000000000..844fafe23
--- /dev/null
+++ b/resources/tester/cad/modify-acad.test.ts
@@ -0,0 +1,374 @@
+/**
+ * 337 다-1 고치기 7 — OFFSET · FILLET · CHAMFER · TRIM · EXTEND · BREAK · JOIN 을 오토캐드 물음 차례 · 옵션 · 기본값 ·
+ * 빈 Enter · Esc · 끝난 뒤 동작으로(설계 `docs/raw/조사/2026-10-15_337_CAD오토캐드조작_설계.md` 1-2 · 6-3 다 줄).
+ * 기억(OFFSETDIST · FILLETRAD · CHAMFERA/B · TRIMMODE)은 파일 안 세션 하나 — 시험 차례대로 이어짐.
+ * 실행: cd B07_DesignDetail/openwebcad && npx vitest run --dir ../../resources/tester/cad modify-acad
+ */
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+vi.mock("react-toastify", () => ({
+  toast: Object.assign(vi.fn(), { error: vi.fn(), info: vi.fn(), warn: vi.fn(), success: vi.fn() }),
+}));
+
+import { Tool } from "../../../B07_DesignDetail/openwebcad/src/tools";
+import { activeTool, click, entities, initIdle, key, promptLine, type } from "./helpers/cad-drive";
+
+type Shape = { start: { x: number; y: number }; end: { x: number; y: number } };
+const enter = () => key("Enter");
+const r = (value: number) => Math.round(value * 1e4) / 1e4;
+/** 선 하나 — 쉼에서 그리고 Esc 로 끝 */
+const line = (a: string, b: string) => {
+  type("l");
+  type(a);
+  type(b);
+  key("Escape");
+};
+/** 선마다 [x1, y1, x2, y2] — 차례 무관(정렬) */
+const segs = () =>
+  entities("Line")
+    .map((entity) => {
+      const { start, end } = entity.getShape() as unknown as Shape;
+      return [r(start.x), r(start.y), r(end.x), r(end.y)];
+    })
+    .sort((a, b) => a[0] - b[0] || a[1] - b[1] || a[2] - b[2] || a[3] - b[3]);
+const ys = () =>
+  segs()
+    .map((s) => s[1])
+    .sort((a, b) => a - b);
+
+beforeEach(() => {
+  initIdle();
+});
+
+describe("OFFSET", () => {
+  it("처음 <통과점> · 통과점 · 되풀이 · 거리 기억 · T · 빈 Enter 끝", () => {
+    line("0,0", "100,0");
+    type("o");
+    expect(activeTool()).toBe(Tool.OFFSET);
+    expect(promptLine()).toBe("간격띄우기 거리 지정 또는 [통과점(T)/지우기(E)] <통과점>:");
+    enter(); // <통과점>
+    expect(promptLine()).toBe("간격띄우기할 객체 선택 또는 [종료(E)/명령 취소(U)] <종료>:");
+    click(50, 0);
+    expect(promptLine()).toBe("통과점 지정 또는 [종료(E)/다중(M)/명령 취소(U)] <종료>:");
+    type("30,20");
+    expect(ys()).toEqual([0, 20]);
+    expect(promptLine()).toBe("간격띄우기할 객체 선택 또는 [종료(E)/명령 취소(U)] <종료>:"); // 되풀이
+    key("Escape");
+    expect(activeTool()).toBe(Tool.SELECT);
+
+    type("o");
+    expect(promptLine()).toBe("간격띄우기 거리 지정 또는 [통과점(T)/지우기(E)] <통과점>:"); // 통과점 기억
+    type("0");
+    expect(activeTool()).toBe(Tool.OFFSET); // 0 거절
+    type("5");
+    click(50, 0);
+    expect(promptLine()).toBe(
+      "간격띄우기할 면의 점 지정 또는 [종료(E)/다중(M)/명령 취소(U)] <종료>:",
+    );
+    type("50,-10");
+    click(50, 20);
+    type("50,30");
+    expect(ys()).toEqual([-5, 0, 20, 25]);
+    enter(); // <종료>
+    expect(activeTool()).toBe(Tool.SELECT);
+
+    type("o");
+    expect(promptLine()).toBe("간격띄우기 거리 지정 또는 [통과점(T)/지우기(E)] <5.0000>:");
+    type("t");
+    click(50, 25);
+    expect(promptLine()).toBe("통과점 지정 또는 [종료(E)/다중(M)/명령 취소(U)] <종료>:");
+    type("e"); // 종료
+    expect(activeTool()).toBe(Tool.SELECT);
+    type("o");
+    expect(promptLine()).toBe("간격띄우기 거리 지정 또는 [통과점(T)/지우기(E)] <통과점>:");
+    key("Escape");
+  });
+
+  it("지우기(E) 예 · 다중(M) · 명령 취소(U) · 없는 옵션 L 안내", () => {
+    line("0,0", "100,0");
+    type("o");
+    type("l");
+    expect(activeTool()).toBe(Tool.OFFSET); // 도면층(L) = 이 CAD 에 없음
+    type("e");
+    expect(promptLine()).toBe(
+      "간격띄우기 후 원본 객체를 지우시겠습니까? [예(Y)/아니오(N)] <아니오>:",
+    );
+    type("y");
+    type("10");
+    click(50, 0);
+    type("50,5");
+    expect(ys()).toEqual([10]); // 원본 지움
+    key("Escape");
+
+    type("o");
+    type("e");
+    expect(promptLine()).toBe("간격띄우기 후 원본 객체를 지우시겠습니까? [예(Y)/아니오(N)] <예>:");
+    type("n");
+    enter(); // <10.0000>
+    click(50, 10);
+    type("m");
+    expect(promptLine()).toBe("간격띄우기할 면의 점 지정 또는 [종료(E)/명령 취소(U)] <다음 객체>:");
+    type("50,100");
+    type("50,100");
+    expect(ys()).toEqual([10, 20, 30]); // 방금 만든 것에서 되풀이 · 원본 둠
+    type("u");
+    expect(ys()).toEqual([10, 20]);
+    expect(promptLine()).toBe("간격띄우기할 객체 선택 또는 [종료(E)/명령 취소(U)] <종료>:");
+    type("u");
+    type("u"); // 이 명령에서 만든 것 없음 = 그대로
+    expect(ys()).toEqual([10]);
+    enter();
+    expect(activeTool()).toBe(Tool.SELECT);
+  });
+});
+
+/** ㄱ 자 — 가로 (0,0)~(100,0) · 세로 (80,−20)~(80,100) · 구석 (80, 0) */
+const corner = () => {
+  line("0,0", "100,0");
+  line("80,-20", "80,100");
+};
+
+describe("FILLET", () => {
+  it("물음 글 · R 기억 · 쌍 하나 뒤 끝", () => {
+    corner();
+    type("f");
+    expect(promptLine()).toBe("첫 번째 객체 선택 또는 [명령 취소(U)/반지름(R)/자르기(T)/다중(M)]:");
+    type("r");
+    expect(promptLine()).toBe("모깎기 반지름 지정 <0.0000>:");
+    type("10");
+    expect(promptLine()).toBe("첫 번째 객체 선택 또는 [명령 취소(U)/반지름(R)/자르기(T)/다중(M)]:");
+    click(30, 0);
+    expect(promptLine()).toBe(
+      "두 번째 객체 선택 또는 Shift 키를 누른 채 선택하여 구석 적용 또는 [반지름(R)]:",
+    );
+    click(80, 60);
+    expect(segs()).toEqual([
+      [0, 0, 70, 0],
+      [80, 100, 80, 10],
+    ]);
+    expect(entities("Arc")).toHaveLength(1);
+    expect(activeTool()).toBe(Tool.SELECT);
+
+    type("f");
+    type("r");
+    expect(promptLine()).toBe("모깎기 반지름 지정 <10.0000>:");
+    key("Escape");
+    expect(activeTool()).toBe(Tool.SELECT);
+  });
+
+  it("다중(M) · Shift = 반지름 0 구석 · 명령 취소(U) · 자르기(T) 자르지 않기 · 빈 Enter 끝", () => {
+    corner();
+    const before = segs();
+    type("f");
+    type("m");
+    click(30, 0);
+    click(80, 60, { shiftKey: true });
+    expect(segs()).toEqual([
+      [0, 0, 80, 0],
+      [80, 100, 80, 0],
+    ]);
+    expect(entities("Arc")).toHaveLength(0);
+    expect(promptLine()).toBe("첫 번째 객체 선택 또는 [명령 취소(U)/반지름(R)/자르기(T)/다중(M)]:"); // 다중 되풀이
+    type("u");
+    expect(segs()).toEqual(before);
+    type("t");
+    expect(promptLine()).toBe("자르기 모드 옵션 입력 [자르기(T)/자르지 않기(N)] <자르기>:");
+    type("n");
+    click(30, 0);
+    click(80, 60);
+    expect(segs()).toEqual(before); // 안 자름
+    expect(entities("Arc")).toHaveLength(1);
+    enter();
+    expect(activeTool()).toBe(Tool.SELECT);
+
+    type("f");
+    type("t");
+    expect(promptLine()).toBe("자르기 모드 옵션 입력 [자르기(T)/자르지 않기(N)] <자르지 않기>:");
+    type("t");
+    key("Escape");
+  });
+});
+
+describe("CHAMFER", () => {
+  it("D 기억(둘째 기본 = 첫째) · 모따기 선 · 한 번 뒤 끝", () => {
+    corner();
+    type("cha");
+    expect(activeTool()).toBe(Tool.CHAMFER);
+    expect(promptLine()).toBe("첫 번째 선 선택 또는 [명령 취소(U)/거리(D)/자르기(T)/다중(M)]:");
+    type("d");
+    expect(promptLine()).toBe("첫 번째 모따기 거리 지정 <0.0000>:");
+    type("10");
+    expect(promptLine()).toBe("두 번째 모따기 거리 지정 <10.0000>:");
+    enter();
+    click(30, 0);
+    expect(promptLine()).toBe(
+      "두 번째 선 선택 또는 Shift 키를 누른 채 선택하여 구석 적용 또는 [거리(D)]:",
+    );
+    click(80, 60);
+    expect(segs()).toEqual([
+      [0, 0, 70, 0],
+      [70, 0, 80, 10],
+      [80, 100, 80, 10],
+    ]);
+    expect(activeTool()).toBe(Tool.SELECT);
+
+    type("cha");
+    type("d");
+    expect(promptLine()).toBe("첫 번째 모따기 거리 지정 <10.0000>:");
+    type("4");
+    expect(promptLine()).toBe("두 번째 모따기 거리 지정 <4.0000>:");
+    key("Escape");
+  });
+
+  it("Shift = 거리 0 구석", () => {
+    corner();
+    type("cha");
+    click(30, 0);
+    click(80, 60, { shiftKey: true });
+    expect(segs()).toEqual([
+      [0, 0, 80, 0],
+      [80, 100, 80, 0],
+    ]);
+  });
+});
+
+describe("TRIM", () => {
+  /** 가로 (0,0)~(100,0) · 세로 둘 x = 30 · 70 */
+  const fence = () => {
+    line("0,0", "100,0");
+    line("30,-20", "30,20");
+    line("70,-20", "70,20");
+  };
+
+  it("되풀이 · 반경 밖 무시 · U · 지우기(R) · 빈 Enter 끝", () => {
+    fence();
+    type("tr");
+    expect(activeTool()).toBe(Tool.ERASER);
+    expect(promptLine()).toBe(
+      "자를 객체 선택 또는 Shift 키를 누른 채 선택하여 연장 또는 [지우기(R)]:",
+    );
+    click(50, 0);
+    expect(segs()).toContainEqual([0, 0, 30, 0]);
+    expect(segs()).toContainEqual([70, 0, 100, 0]);
+    expect(segs()).toHaveLength(4);
+    click(50, 50); // 집기 반경 밖
+    expect(segs()).toHaveLength(4);
+    type("u");
+    expect(segs()).toContainEqual([0, 0, 100, 0]);
+    click(50, 0);
+    click(30, 15);
+    expect(segs()).toContainEqual([30, -20, 30, 0]);
+    expect(activeTool()).toBe(Tool.ERASER); // 되풀이
+    type("r");
+    expect(promptLine()).toBe("지울 객체 선택:");
+    click(70, 10);
+    enter();
+    expect(segs().some((s) => s[0] === 70 && s[2] === 70)).toBe(false);
+    expect(promptLine()).toBe(
+      "자를 객체 선택 또는 Shift 키를 누른 채 선택하여 연장 또는 [지우기(R)]:",
+    );
+    type("c");
+    expect(activeTool()).toBe(Tool.ERASER); // 걸치기(C) = 이 CAD 에 없음
+    enter();
+    expect(activeTool()).toBe(Tool.SELECT);
+  });
+
+  it("Esc 한 번 = 끝 · Shift = 연장", () => {
+    line("0,0", "50,0");
+    line("80,-20", "80,20");
+    type("tr");
+    click(40, 0, { shiftKey: true });
+    expect(segs()).toContainEqual([0, 0, 80, 0]);
+    key("Escape");
+    expect(activeTool()).toBe(Tool.SELECT);
+  });
+
+  it("사각형 변 = 원래 도면층 · 꼴(N9)", () => {
+    type("rec");
+    type("0,0");
+    type("100,40");
+    key("Escape");
+    const rectangle = entities("Rectangle")[0];
+    rectangle.layerId = "L2";
+    rectangle.lineColor = "#ff0000";
+    line("20,-10", "20,50");
+    type("tr");
+    click(60, 40);
+    const sides = entities("Line").filter((entity) => entity.layerId === "L2");
+    expect(sides.length).toBe(4);
+    expect(sides.every((entity) => entity.lineColor === "#ff0000")).toBe(true);
+    expect(segs()).toContainEqual([0, 40, 20, 40]);
+  });
+});
+
+describe("EXTEND", () => {
+  it("빠른 연장 · 되풀이 · Shift = 자르기 · 빈 Enter 끝", () => {
+    line("0,0", "50,0");
+    line("80,-20", "80,20");
+    type("ex");
+    expect(activeTool()).toBe(Tool.EXTEND);
+    expect(promptLine()).toBe("연장할 객체 선택 또는 Shift 키를 누른 채 선택하여 자르기:");
+    click(40, 0);
+    expect(segs()).toContainEqual([0, 0, 80, 0]);
+    click(80, 10, { shiftKey: true });
+    expect(segs()).toContainEqual([80, -20, 80, 0]);
+    expect(activeTool()).toBe(Tool.EXTEND);
+    enter();
+    expect(activeTool()).toBe(Tool.SELECT);
+  });
+});
+
+describe("BREAK", () => {
+  it("누른 점 = 첫 끊기점 · 둘째 점 · 한 번 뒤 끝", () => {
+    line("0,0", "100,0");
+    type("br");
+    expect(promptLine()).toBe("객체 선택:");
+    click(20, 0);
+    expect(promptLine()).toBe("두 번째 끊기점 지정 또는 [첫 번째 점(F)]:");
+    type("60,0");
+    expect(segs()).toEqual([
+      [0, 0, 20, 0],
+      [60, 0, 100, 0],
+    ]);
+    expect(activeTool()).toBe(Tool.SELECT);
+  });
+
+  it("첫 번째 점(F) · `@0,0` = 같은 점(틈 없이 둘)", () => {
+    line("0,0", "100,0");
+    type("br");
+    click(50, 0);
+    type("f");
+    expect(promptLine()).toBe("첫 번째 끊기점 지정:");
+    type("10,0");
+    expect(promptLine()).toBe("두 번째 끊기점 지정:");
+    type("30,0");
+    expect(segs()).toEqual([
+      [0, 0, 10, 0],
+      [30, 0, 100, 0],
+    ]);
+
+    type("br");
+    click(60, 0);
+    type("@0,0");
+    expect(segs()).toEqual([
+      [0, 0, 10, 0],
+      [30, 0, 60, 0],
+      [60, 0, 100, 0],
+    ]);
+  });
+});
+
+describe("JOIN", () => {
+  it("고르기 물음 글 · 빈 Enter = 결합 · 한 번 뒤 끝", () => {
+    line("0,0", "40,0");
+    line("40,0", "40,40");
+    type("j");
+    expect(promptLine()).toBe("한 번에 결합할 원본 객체 또는 여러 객체 선택:");
+    click(20, 0);
+    click(40, 20);
+    enter();
+    expect(entities("Line")).toHaveLength(0);
+    expect(entities("PolyLine")).toHaveLength(1);
+    expect(activeTool()).toBe(Tool.SELECT);
+  });
+});