diff --git a/M02_MasterTemplete/M02_MasterTemplete_Api_Fetch.ts b/M02_MasterTemplete/M02_MasterTemplete_Api_Fetch.ts
index df250b19..9fe59d66 100644
--- a/M02_MasterTemplete/M02_MasterTemplete_Api_Fetch.ts
+++ b/M02_MasterTemplete/M02_MasterTemplete_Api_Fetch.ts
@@ -35,7 +35,8 @@ async function call<T>(path: string, init: RequestInit = {}): Promise<T> {
     ...init,
   });
   const body = (await response.json().catch(() => ({}))) as { detail?: unknown } & T;
-  if (response.status === 409) throw new StaleError(String(body.detail ?? "409"));
+  if (response.status === 409)
+    throw new StaleError(typeof body.detail === "string" ? body.detail : "409");
   if (!response.ok) {
     const detail = body.detail;
     throw new Error(typeof detail === "string" ? detail : `HTTP ${response.status}`);
@@ -82,6 +83,14 @@ export const saveTemplate = (
 export const deleteTemplate = (kind: Kind, name: string, 판: string): Promise<{ ok: boolean }> =>
   call(`/templates/${kind}/${enc(name)}?판=${enc(판)}`, { method: "DELETE" });
 
+/** 개인·회사 층에서 지움 — 서버 길은 sub4 (없으면 404) */
+export const deleteLayerTemplate = (
+  layer: Layer,
+  kind: Kind,
+  name: string,
+): Promise<{ ok: boolean }> =>
+  call(`/layers/${layer}/templates/${kind}/${enc(name)}`, { method: "DELETE" });
+
 /* --- 프로젝트 층 단추 다섯 --- */
 const project = (id: string, tail: string): string => `/projects/${enc(id)}/templates/${tail}`;
 const post = (path: string, body: object = {}): Promise<unknown> =>
diff --git a/M02_MasterTemplete/M02_MasterTemplete_Drawing.ts b/M02_MasterTemplete/M02_MasterTemplete_Drawing.ts
index b3bbbecb..4b441c12 100644
--- a/M02_MasterTemplete/M02_MasterTemplete_Drawing.ts
+++ b/M02_MasterTemplete/M02_MasterTemplete_Drawing.ts
@@ -34,6 +34,8 @@ export interface DrawingTemplateOptions {
   layer?: string;
   /** 프로젝트 층이면 프로젝트 id — 칸이 `m02:project:프로젝트id:이름` 이 된다. */
   projectId?: string | null;
+  /** 저장 안 한 고침이 생기면 true — CAD 편집 · 작도 영역 값 바꿈. */
+  onChanged?: (dirty: boolean) => void;
 }
 
 const RECOVERY_PREFIX = "OPEN_WEB_CAD__RECOVERY__";
@@ -128,6 +130,7 @@ export function mountDrawingTemplate(
   const areaInputs = AREA_LABELS.map((label, index) => {
     const field = createInputField({ label, type: "number", value: String(start[index]) });
     field.input.disabled = readOnly;
+    field.input.addEventListener("input", () => options.onChanged?.(true));
     return field;
   });
   area.append(areaTitle, ...areaInputs.map((field) => field.root));
@@ -167,7 +170,10 @@ export function mountDrawingTemplate(
       showToast(error instanceof Error ? error.message : "자리표 목록을 받지 못했습니다.", "error"),
     );
 
-  const cad = createCadHost<DrawingTemplateDoc>({ title: "도면 양식" });
+  const cad = createCadHost<DrawingTemplateDoc>({
+    title: "도면 양식",
+    onChanged: (dirty) => options.onChanged?.(dirty),
+  });
   const load = (drawing: DrawingTemplateDoc): void => {
     cad.beginLoading();
     cad.load(
diff --git a/M02_MasterTemplete/M02_MasterTemplete_Store.py b/M02_MasterTemplete/M02_MasterTemplete_Store.py
index 5ee4c9e7..3573c1d4 100644
--- a/M02_MasterTemplete/M02_MasterTemplete_Store.py
+++ b/M02_MasterTemplete/M02_MasterTemplete_Store.py
@@ -18,7 +18,7 @@ from common_util.common_util_json import atomic_write_json
 
 FOLDER: Path = Path(__file__).resolve().parent.parent / "resources" / "master_template"
 KINDS = ("table", "drawing")  # 시험은 FOLDER 를 사본으로 바꿈
-_BAD_NAME = re.compile(r'[\/:*?"<>|\x00-\x1f]')
+_BAD_NAME = re.compile(r'[\\/:*?"<>|\x00-\x1f]|\.\.')
 # ponytail: 저장은 한 번에 하나(프로세스 안 잠금) · 서버를 여럿 띄우면 파일 잠금으로
 _LOCK = threading.Lock()
 
@@ -37,7 +37,7 @@ def _path(kind: str, name: str) -> Path:
     if kind not in KINDS:
         raise StoreError(404, f"없는 종류 「{kind}」")
     if not name or name != name.strip() or name.startswith(".") or _BAD_NAME.search(name):
-        raise StoreError(422, f"쓸 수 없는 이름 「{name}」")
+        raise StoreError(400, f"쓸 수 없는 글자가 있는 이름 「{name}」")
     return FOLDER / kind / f"{name}.json"
 
 
diff --git a/M02_MasterTemplete/M02_MasterTemplete_UI_Main.ts b/M02_MasterTemplete/M02_MasterTemplete_UI_Main.ts
index 8df33ece..516c1bae 100644
--- a/M02_MasterTemplete/M02_MasterTemplete_UI_Main.ts
+++ b/M02_MasterTemplete/M02_MasterTemplete_UI_Main.ts
@@ -4,7 +4,7 @@
  * 부품 파일이 없거나 못 읽어도 페이지는 뜸 — 빈 자리 글.
  * ========================================================================== */
 
-import { createButton, el, showToast } from "@ui/ui_template_elements";
+import { createButton, el, showConfirmDialog, showToast } from "@ui/ui_template_elements";
 import { t as L } from "@ui/ui_template_locale";
 import {
   readFilled,
@@ -48,6 +48,8 @@ export interface MainHandle {
   root: HTMLElement;
   open: (sel: Selection | null) => Promise<void>;
   current: () => Selection | null;
+  /** 저장 안 한 고침이 있으면 버릴지 물음 — 취소면 false */
+  confirmLeave: () => Promise<boolean>;
 }
 
 /** 이 층에서 고칠 수 있나 — 시스템은 관리자만 · 회사는 여기서 못 고침(공식으로 저장으로만) */
@@ -75,6 +77,21 @@ export function createMain(isAdmin: boolean, onSaved?: () => void): MainHandle {
   let loaded: unknown = null;
   let editor: EditorHandle | null = null;
   let seq = 0;
+  let dirty = false;
+
+  const guard = (event: BeforeUnloadEvent): void => {
+    if (!root.isConnected) return window.removeEventListener("beforeunload", guard);
+    if (!dirty) return;
+    event.preventDefault();
+    event.returnValue = "";
+  };
+  window.addEventListener("beforeunload", guard);
+  const confirmLeave = async (): Promise<boolean> => {
+    if (!dirty) return true;
+    if (!(await showConfirmDialog(L("M02_DiscardConfirm")))) return false;
+    dirty = false;
+    return true;
+  };
 
   const showNotice = (nodes: (HTMLElement | string)[]): void => {
     notice.replaceChildren(...nodes);
@@ -102,7 +119,10 @@ export function createMain(isAdmin: boolean, onSaved?: () => void): MainHandle {
         "createSheet",
       );
       if (create) {
-        editor = create(host, doc, { mode: at.layer === "project" ? "project" : "master" });
+        editor = create(host, doc, {
+          mode: at.layer === "project" ? "project" : "master",
+          onChange: () => (dirty = !readOnly),
+        });
         return;
       }
       return empty(L("M02_NoSheet"));
@@ -118,6 +138,7 @@ export function createMain(isAdmin: boolean, onSaved?: () => void): MainHandle {
         name: at.name,
         layer: at.layer,
         projectId: at.projectId,
+        onChanged: (d: boolean) => (dirty = d && !readOnly),
       });
       return;
     }
@@ -126,6 +147,7 @@ export function createMain(isAdmin: boolean, onSaved?: () => void): MainHandle {
 
   async function open(next: Selection | null): Promise<void> {
     const mine = ++seq;
+    dirty = false;
     drop();
     showNotice([]);
     sel = next;
@@ -166,6 +188,7 @@ export function createMain(isAdmin: boolean, onSaved?: () => void): MainHandle {
       const info = await saveTemplate(at.layer, at.kind, at.name, at.projectId, version, doc);
       version = info.판;
       loaded = doc;
+      dirty = false;
       showNotice([]);
       showToast(L("M02_Saved"), "success");
       onSaved?.(); // 좌측 목록의 판을 새 판으로
@@ -182,8 +205,10 @@ export function createMain(isAdmin: boolean, onSaved?: () => void): MainHandle {
   }
 
   save.addEventListener("click", () => void doSave());
-  reload.addEventListener("click", () => sel && void open(sel));
+  reload.addEventListener("click", async () => {
+    if (sel && (await confirmLeave())) void open(sel);
+  });
   bar();
   empty("");
-  return { root, open, current: () => sel };
+  return { root, open, current: () => sel, confirmLeave };
 }
diff --git a/M02_MasterTemplete/M02_MasterTemplete_UI_Page.ts b/M02_MasterTemplete/M02_MasterTemplete_UI_Page.ts
index 640f0dd4..f52b511b 100644
--- a/M02_MasterTemplete/M02_MasterTemplete_UI_Page.ts
+++ b/M02_MasterTemplete/M02_MasterTemplete_UI_Page.ts
@@ -20,9 +20,11 @@ export async function renderM02MasterTemplate(root: HTMLElement): Promise<void>
   const main = createMain(isAdmin, () => void side.refresh());
   const side = buildSide({
     isAdmin,
+    isCompanyAdmin: isAdmin || user?.role === "ADMIN" || !!user?.is_master,
     userName: user?.name,
     onOpen: (sel) => void main.open(sel),
     getOpen: main.current,
+    confirmLeave: main.confirmLeave,
   });
 
   const layout = el("div", { className: "ui-workflow-layout m02-master" });
diff --git a/M02_MasterTemplete/M02_MasterTemplete_UI_Side.ts b/M02_MasterTemplete/M02_MasterTemplete_UI_Side.ts
index 8a618795..b9474ecc 100644
--- a/M02_MasterTemplete/M02_MasterTemplete_UI_Side.ts
+++ b/M02_MasterTemplete/M02_MasterTemplete_UI_Side.ts
@@ -17,6 +17,7 @@ import { openModal } from "@ui/ui_template_modal";
 import { fetchUserProjects, type ProjectItem } from "../B01_Dashboard/B01_Dashboard_Api_Fetch";
 import {
   applyToProject,
+  deleteLayerTemplate,
   deleteTemplate,
   fetchSources,
   listTemplates,
@@ -24,6 +25,7 @@ import {
   resetProject,
   saveProjectAs,
   saveTemplate,
+  StaleError,
   type Kind,
   type Layer,
   type TemplateInfo,
@@ -78,10 +80,14 @@ const store = {
 
 export interface SideOptions {
   isAdmin: boolean;
+  /** 회사 관리자(회사 층 지우기 · 회사 공식으로 저장) */
+  isCompanyAdmin?: boolean;
   /** 로그인한 사용자 이름 — 프로젝트 기본값(내가 만든 최근 것)에 씀 */
   userName?: string;
   onOpen: (sel: Selection | null) => void;
   getOpen: () => Selection | null;
+  /** 저장 안 한 고침을 버릴지 확인 — 취소면 false */
+  confirmLeave: () => Promise<boolean>;
 }
 
 export interface SideHandle {
@@ -89,6 +95,10 @@ export interface SideHandle {
   refresh: () => Promise<void>;
 }
 
+/** 서버 이름 규칙과 같게 — 화면에서 먼저 막음 */
+const badName = (name: string): boolean =>
+  /[\\/:*?"<>|\x00-\x1f]|\.\./.test(name) || name.startsWith(".");
+
 const why = (error: unknown): string => (error instanceof Error ? error.message : "");
 const failed = (error: unknown): void =>
   showToast(L("M02_ActionFailed").replace("{value}", why(error)), "error");
@@ -144,7 +154,8 @@ export function buildSide(opt: SideOptions): SideHandle {
   const layerButtons = LAYERS.map(({ layer: id, label }) => {
     const button = createButton({ label: label(), variant: "ghost" });
     button.disabled = id === "system" && !opt.isAdmin;
-    button.addEventListener("click", () => {
+    button.addEventListener("click", async () => {
+      if (id !== layer && !(await opt.confirmLeave())) return;
       layer = id;
       store.set(LAYER_KEY, id);
       opt.onOpen(null);
@@ -173,7 +184,11 @@ export function buildSide(opt: SideOptions): SideHandle {
   };
 
   const projectField = createSelectField({ label: L("M02_Project"), options: [] });
-  projectField.select.addEventListener("change", () => {
+  projectField.select.addEventListener("change", async () => {
+    if (!(await opt.confirmLeave())) {
+      projectField.select.value = projectId;
+      return;
+    }
     projectId = projectField.select.value;
     remember(projectId);
     opt.onOpen(null);
@@ -221,7 +236,7 @@ export function buildSide(opt: SideOptions): SideHandle {
                     text: info.이름,
                     attrs: { type: "button", title: info.수정일 },
                   });
-                  b.addEventListener("click", () => select(info));
+                  b.addEventListener("click", () => void select(info));
                   return b;
                 })
               : [el("p", { className: "m02-side__empty", text: L("M02_NoTemplates") })]),
@@ -235,14 +250,19 @@ export function buildSide(opt: SideOptions): SideHandle {
     layerButtons.forEach(({ id, button }) => button.classList.toggle("is-active", id === layer));
     projectField.root.hidden = !isProject();
     const editable = layer === "system" && canEdit(layer, opt.isAdmin);
-    editRow.hidden = layer !== "system";
+    const canDelete =
+      editable || layer === "personal" || (layer === "company" && !!opt.isCompanyAdmin);
+    editRow.hidden = isProject();
+    btnNew.hidden = btnCopy.hidden = layer !== "system";
     btnNew.disabled = !editable;
-    btnCopy.disabled = btnDel.disabled = !editable || !currentInfo();
+    btnCopy.disabled = !editable || !currentInfo();
+    btnDel.disabled = !canDelete || !currentInfo();
     projectRow.hidden = !isProject();
     projectRow.querySelectorAll("button").forEach((b) => (b.disabled = !projectId));
   }
 
-  function select(info: TemplateInfo): void {
+  async function select(info: TemplateInfo): Promise<void> {
+    if (!isOpen(info) && !(await opt.confirmLeave())) return;
     opt.onOpen({ layer, projectId: pid(), kind: info.종류, name: info.이름 });
     paintList();
     paintButtons();
@@ -298,11 +318,16 @@ export function buildSide(opt: SideOptions): SideHandle {
         ok.addEventListener("click", async () => {
           const text = name.input.value.trim();
           if (!text) return showToast(L("M02_NameNeeded"), "error");
+          if (badName(text)) return showToast(L("M02_BadName"), "error");
+          ok.disabled = true; // 연달아 눌러도 한 번만
           try {
             await onOk(kind.select.value as Kind, text);
             close();
           } catch (error) {
-            failed(error);
+            if (error instanceof StaleError) showToast(L("M02_NameExists"), "error");
+            else failed(error);
+          } finally {
+            ok.disabled = false;
           }
         });
         body.append(...(withKind ? [kind.root] : []), name.root, ok);
@@ -315,7 +340,7 @@ export function buildSide(opt: SideOptions): SideHandle {
     showToast(L("M02_Created"), "success");
     await refresh();
     const info = items.find((i) => i.종류 === kind && i.이름 === name);
-    if (info) select(info);
+    if (info) await select(info);
   };
 
   btnNew.addEventListener("click", () =>
@@ -339,7 +364,8 @@ export function buildSide(opt: SideOptions): SideHandle {
     if (!info) return;
     if (!(await showConfirmDialog(L("M02_DeleteConfirm").replace("{value}", info.이름)))) return;
     try {
-      await deleteTemplate(info.종류, info.이름, info.판);
+      if (layer === "system") await deleteTemplate(info.종류, info.이름, info.판);
+      else await deleteLayerTemplate(layer, info.종류, info.이름);
       showToast(L("M02_Deleted"), "success");
       opt.onOpen(null);
       await refresh();
@@ -350,6 +376,7 @@ export function buildSide(opt: SideOptions): SideHandle {
 
   /* --- 프로젝트 층 단추 다섯 — 길은 계약 · 아직 없으면 404 를 토스트로 --- */
   const act = async (run: () => Promise<unknown>): Promise<void> => {
+    if (!(await opt.confirmLeave())) return;
     try {
       await run();
       showToast(L("M02_Done"), "success");
@@ -364,9 +391,21 @@ export function buildSide(opt: SideOptions): SideHandle {
     b.addEventListener("click", onClick);
     projectRow.append(b);
   };
-  const saveOpenAs = (to: "personal" | "company"): void => {
+  const saveOpenAs = async (to: "personal" | "company"): Promise<void> => {
     const cur = opt.getOpen();
     if (!cur) return void showToast(L("M02_PickTemplate"), "error");
+    try {
+      const rows = await listTemplates(to, null);
+      const same = rows.some((r) => r.종류 === cur.kind && r.이름 === cur.name);
+      if (
+        same &&
+        !(await showConfirmDialog(L("M02_OverwriteConfirm").replace("{value}", cur.name)))
+      ) {
+        return;
+      }
+    } catch (error) {
+      return failed(error);
+    }
     void act(() => saveProjectAs(projectId, to, cur.kind, cur.name));
   };
   projectButton(L("M02_ProjectReset"), async () => {
@@ -407,8 +446,8 @@ export function buildSide(opt: SideOptions): SideHandle {
       },
     });
   });
-  projectButton(L("M02_ProjectSavePersonal"), () => saveOpenAs("personal"));
-  projectButton(L("M02_ProjectSaveCompany"), () => saveOpenAs("company"));
+  projectButton(L("M02_ProjectSavePersonal"), () => void saveOpenAs("personal"));
+  projectButton(L("M02_ProjectSaveCompany"), () => void saveOpenAs("company"));
 
   void refresh();
   return { root, refresh };
diff --git a/resources/tester/test_m02_store.py b/resources/tester/test_m02_store.py
index c6090378..53f01325 100644
--- a/resources/tester/test_m02_store.py
+++ b/resources/tester/test_m02_store.py
@@ -47,13 +47,9 @@ def test_new_save_reopen_delete_and_stale(client):
 
 
 def test_bad_names_and_kinds(client):
-    assert (
-        client.put("/api/m02/templates/table/a..b", json={"판": "", "문서": {"열": []}}).status_code
-        == 200
-    )
-    assert (
-        client.put("/api/m02/templates/table/.숨김", json={"판": "", "문서": {}}).status_code == 422
-    )
+    for bad in ("a..b", ".숨김", "a%5Cb", "a%3Ab"):
+        got = client.put(f"/api/m02/templates/table/{bad}", json={"판": "", "문서": {"열": []}})
+        assert got.status_code == 400 and "쓸 수 없는" in got.json()["detail"]
     assert client.put("/api/m02/templates/other/x", json={"판": "", "문서": {}}).status_code == 404
 
 
diff --git a/ui_template/ui_template_locale_m2.ts b/ui_template/ui_template_locale_m2.ts
index cb4a8225..47757e43 100644
--- a/ui_template/ui_template_locale_m2.ts
+++ b/ui_template/ui_template_locale_m2.ts
@@ -59,6 +59,16 @@ export const ui_locales_m2 = {
   ],
   M02_ImportTitle: ["양식 가져오기", "Import template"],
   M02_ImportNone: ["가져올 양식 없음", "Nothing to import"],
+  M02_NameExists: ["이미 있는 이름", "That name already exists"],
+  M02_BadName: [
+    '쓸 수 없는 글자 — / \\ : * ? " < > | 와 .. · 앞의 점은 안 됨',
+    'Invalid name — no / \\ : * ? " < > | or .. or leading dot',
+  ],
+  M02_DiscardConfirm: [
+    "저장 안 한 고침이 있음 — 버리고 넘어갈까?",
+    "Unsaved changes — discard and continue?",
+  ],
+  M02_OverwriteConfirm: ["「{value}」 이(가) 이미 있음 — 덮을까?", "“{value}” exists — overwrite?"],
   M02_Done: ["했음", "Done"],
   M02_ActionFailed: ["안 됨 — {value}", "Failed — {value}"],
 } as const;