diff --git a/A00_Common/spreadsheet/spreadsheet.ts b/A00_Common/spreadsheet/spreadsheet.ts
index ba56a878..05764e6f 100644
--- a/A00_Common/spreadsheet/spreadsheet.ts
+++ b/A00_Common/spreadsheet/spreadsheet.ts
@@ -6,7 +6,7 @@
  * 키 · 마우스)을 잇음. 한글 조합 = 숨은 textarea 에 늘 초점 · compositionstart 로 편집 시작(keydown 글자 방식 금지).
  * ⚠ M02 만 `import()` 로 불러옴 — 정적 import 금지(다른 페이지 번들에 안 섞이게).
  * 저장은 부른 쪽 몫(`onChange` 로 문서 · 자동저장 없음 · [저장] 때 서버가 Node 로 다시 풂).
- * 화면 차례: 도구 모음(E) · 주소 상자 + 수식 입력줄(D) · 격자(C) · 시트 탭(E).
+ * 화면 차례: 도구 모음(E) · 주소 상자 + 수식 입력줄(D) · 격자(C) · 시트 탭(E) · 상태 표시줄(sub4).
  * 2단계 부품(찾기 · 메모 · 서식 붓 · 골라 붙여넣기)은 `spreadsheet_extras.ts` 로 이음.
  * ========================================================================== */
 
@@ -24,6 +24,7 @@ import { attachKeys } from "./spreadsheet_keys";
 import { attachMenu } from "./spreadsheet_menu";
 import { attachMouse } from "./spreadsheet_mouse";
 import { LAST_C, LAST_R, selectCell } from "./spreadsheet_selection";
+import { createStatusBar } from "./spreadsheet_statusbar";
 import { mountTabs } from "./spreadsheet_tabs";
 import { mountToolbar } from "./spreadsheet_toolbar";
 import type {
@@ -128,10 +129,12 @@ export function createSpreadsheet(
   const tabs = mountTabs(ctx);
   const menu: PartHandle | null = readOnly ? null : attachMenu(ctx);
   const clip = attachClipboard(ctx);
-  const others = [toolbar, tabs, menu, clip].filter((p): p is PartHandle => !!p);
+  const status = createStatusBar(ctx);
+  const others = [toolbar, tabs, menu, clip, status].filter((p): p is PartHandle => !!p);
 
   grid.root.classList.add("ss-grid-host");
-  for (const node of [toolbar?.root, ed.bar, grid.root, tabs.root]) if (node) root.append(node);
+  for (const node of [toolbar?.root, ed.bar, grid.root, tabs.root, status.root])
+    if (node) root.append(node);
   const extras = attachExtras(ctx, ed, toolbar?.root ?? null);
   others.push(...extras.parts);
   const detachKeys = attachKeys(ctx, ed, extras.keys);
diff --git a/A00_Common/spreadsheet/spreadsheet_data_menu.ts b/A00_Common/spreadsheet/spreadsheet_data_menu.ts
index 4b023d90..63721d63 100644
--- a/A00_Common/spreadsheet/spreadsheet_data_menu.ts
+++ b/A00_Common/spreadsheet/spreadsheet_data_menu.ts
@@ -2,18 +2,24 @@
  * spreadsheet_data_menu.ts  (주인 D)
  * 데이터 단추 · 메뉴 잇기 — 수식 입력줄 앞 [↑] [↓] [필터] [데이터 ▾].
  *   정렬 · 자동 필터(sub3 `spreadsheet_sort_dialog` · `spreadsheet_filter`) ·
- *   조건부 서식 · 데이터 유효성 · 이름 관리(sub4 패널 — 부품 오른위 창에 띄움) · 눈금선 보이기/숨기기.
+ *   조건부 서식 · 데이터 유효성 · 이름 관리 · 시트 숨김/탭 색(sub4 패널 — 부품 오른위 창에 띄움) · 눈금선 ·
+ *   수식 분석(sub3 — 선행 · 종속 추적 화살표 · 화살표 지우기 · 수식 계산 · 오류 ⚠ 풍선) · 자동 합계(Σ · Alt+=).
  * 유효성 목록 칸은 고르면 칸 옆 ▼ · Alt+↓ 로 값 목록(필터 머리 칸이면 필터 목록이 먼저).
  * ========================================================================== */
 
 import "./spreadsheet_stage3.css"; // sub4 패널 스타일(잇는 쪽이 붙임)
-import { createMapContextMenu } from "@ui/ui_template_context_menu";
-import { el } from "@ui/ui_template_elements";
-import { parseRange, toA1 } from "./spreadsheet_address";
+import { createMapContextMenu, type MapContextMenuItem } from "@ui/ui_template_context_menu";
+import { el, showToast } from "@ui/ui_template_elements";
+import { parseRange, rangeToA1, toA1 } from "./spreadsheet_address";
+import { autoSumRange } from "./spreadsheet_autosum";
 import { createCondFmtPanel } from "./spreadsheet_condfmt";
+import { attachErrorTip } from "./spreadsheet_errcheck";
+import { openEvalSteps } from "./spreadsheet_eval_steps";
 import { attachFilter, toggleFilter } from "./spreadsheet_filter";
 import { createNameManagerPanel } from "./spreadsheet_names";
+import { createSheetExtraPanel } from "./spreadsheet_sheet_extra";
 import { openSortDialog, sortSelection } from "./spreadsheet_sort_dialog";
+import { attachTrace } from "./spreadsheet_trace";
 import {
   createValidationDropdown,
   createValidationPanel,
@@ -35,17 +41,32 @@ const TEXT = {
   grid: "눈금선 보이기 · 숨기기",
   close: "닫기",
   list: "값 목록(Alt+↓)",
+  sheets: "시트 숨기기 · 탭 색…",
+  audit: "수식 분석",
+  prec: "선행 참조 추적",
+  dep: "종속 참조 추적",
+  clear: "화살표 지우기",
+  steps: "수식 계산…",
+  noMore: "더 추적할 칸 없음",
+  sum: "자동 합계(Alt+=)",
 };
 
 export interface DataMenu {
   /** 수식 입력줄 앞에 둘 단추들 */
   buttons: HTMLElement[];
-  keys: Pick<KeyHooks, "filter" | "dropdown">;
+  keys: Pick<KeyHooks, "filter" | "dropdown" | "autosum">;
   part: PartHandle;
 }
 
 export function mountDataMenu(ctx: SpreadsheetContext, back: () => void): DataMenu {
   const filter = attachFilter(ctx);
+  const trace = attachTrace(ctx);
+  const tip = attachErrorTip(ctx, trace);
+  let closeSteps: (() => void) | null = null;
+  const traced = (more: boolean): void => {
+    if (!more) showToast(TEXT.noMore, "info");
+    back();
+  };
   const menu = createMapContextMenu("ss");
   ctx.root.append(menu.element);
   let closeSort: (() => void) | null = null;
@@ -97,13 +118,23 @@ export function mountDataMenu(ctx: SpreadsheetContext, back: () => void): DataMe
 
   function openMenu(anchor: HTMLElement): void {
     const r = anchor.getBoundingClientRect();
-    const items: [string, () => void][] = [
+    const items: MapContextMenuItem[] = [
       [TEXT.sort, () => ((closeSort = openSortDialog(ctx)), undefined)],
       [TEXT.filterItem, () => (toggleFilter(ctx), back())],
       [TEXT.condfmt, () => openPanel(TEXT.condfmt, createCondFmtPanel)],
       [TEXT.validation, () => openPanel(TEXT.validation, createValidationPanel)],
       [TEXT.names, () => openPanel(TEXT.names, createNameManagerPanel)],
+      [TEXT.sheets, () => openPanel(TEXT.sheets, createSheetExtraPanel)],
       [TEXT.grid, () => (toggleGridlines(), back())],
+      {
+        label: TEXT.audit,
+        children: [
+          [TEXT.prec, () => traced(trace.precedents())],
+          [TEXT.dep, () => traced(trace.dependents())],
+          [TEXT.clear, () => (trace.clear(), back())],
+          [TEXT.steps, () => (closeSteps?.(), (closeSteps = openEvalSteps(ctx)))],
+        ],
+      },
     ];
     if (!ctx.readOnly) menu.open(r.left, r.bottom, items);
   }
@@ -161,12 +192,19 @@ export function mountDataMenu(ctx: SpreadsheetContext, back: () => void): DataMe
   };
   document.addEventListener("mousedown", onOutside, true);
 
+  /** 자동 합계 — 엑셀처럼 =SUM(잡은 범위) 로 편집을 열고 Enter 는 사용자 몫 */
+  function autosum(): void {
+    const g = autoSumRange(ctx);
+    ctx.editor.begin(g ? `=SUM(${rangeToA1(g)})` : "=SUM()");
+  }
+
   const buttons = ctx.readOnly
     ? []
     : [
         button("↑", TEXT.asc, () => sortSelection(ctx, false)),
         button("↓", TEXT.desc, () => sortSelection(ctx, true)),
         button("필터", TEXT.filter, () => toggleFilter(ctx)),
+        button("Σ", TEXT.sum, autosum, true),
         button(TEXT.menu, TEXT.menu, openMenu, true),
       ];
 
@@ -174,6 +212,7 @@ export function mountDataMenu(ctx: SpreadsheetContext, back: () => void): DataMe
     buttons,
     keys: {
       filter: () => toggleFilter(ctx),
+      autosum,
       dropdown() {
         const f = ctx.sheet().필터;
         const g = f && parseRange(f.범위);
@@ -186,6 +225,8 @@ export function mountDataMenu(ctx: SpreadsheetContext, back: () => void): DataMe
       root: null,
       refresh() {
         filter.refresh();
+        trace.refresh();
+        tip.refresh();
         panel?.refresh();
         closeDrop();
         const { r, c } = ctx.selection.활성;
@@ -203,6 +244,9 @@ export function mountDataMenu(ctx: SpreadsheetContext, back: () => void): DataMe
         closePanel();
         closeDrop();
         filter.destroy();
+        closeSteps?.();
+        trace.destroy();
+        tip.destroy();
         menu.element.remove();
         dialog.remove();
         arrow.remove();
diff --git a/A00_Common/spreadsheet/spreadsheet_keys.ts b/A00_Common/spreadsheet/spreadsheet_keys.ts
index b90a88b0..ed815923 100644
--- a/A00_Common/spreadsheet/spreadsheet_keys.ts
+++ b/A00_Common/spreadsheet/spreadsheet_keys.ts
@@ -43,6 +43,8 @@ export interface KeyHooks {
   escape?(): void;
   /** Ctrl+1 셀 서식 창 */
   formatDialog?(): void;
+  /** Alt+= 자동 합계 */
+  autosum?(): void;
   /** Ctrl+Shift+L 필터 켜기 · 끄기 */
   filter?(): void;
   /** Alt+↓ — 필터 머리 칸이면 값 목록을 열고 true */
@@ -106,6 +108,7 @@ export function attachKeys(ctx: SpreadsheetContext, ed: Editor, hooks: KeyHooks
     const sel = ctx.selection;
     const arrow = ARROWS[e.key];
     if (e.altKey && e.key === "ArrowDown" && hooks.dropdown?.()) return true;
+    if (e.altKey && e.key === "=" && hooks.autosum && !ctx.readOnly) return (hooks.autosum(), true);
     if (arrow && !e.altKey) {
       go(move(sheet, sel, arrow[0], arrow[1], { extend: e.shiftKey, jump: ctrl }));
       return true;