diff --git a/A00_Common/spreadsheet/spreadsheet.css b/A00_Common/spreadsheet/spreadsheet.css
index 9f068cd6..067f5f1a 100644
--- a/A00_Common/spreadsheet/spreadsheet.css
+++ b/A00_Common/spreadsheet/spreadsheet.css
@@ -257,3 +257,52 @@
 .ss-hint__item.is-on {
   background: #ddf4ff;
 }
+
+/* 데이터 메뉴 — 패널 창 · 유효성 목록 ▼ */
+.ss-dialog {
+  position: absolute;
+  top: 4px;
+  right: 16px;
+  z-index: 21;
+  max-height: calc(100% - 8px);
+  overflow: auto;
+  border: 1px solid #d0d7de;
+  border-radius: 6px;
+  background: #fff;
+  box-shadow: 0 4px 12px rgb(0 0 0 / 15%);
+}
+
+.ss-dialog[hidden],
+.ss-list-arrow[hidden] {
+  display: none;
+}
+
+.ss-dialog__head {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 8px;
+  padding: 6px 8px;
+  border-bottom: 1px solid #d0d7de;
+  font-weight: bold;
+}
+
+.ss-dialog__body {
+  padding: 8px;
+}
+
+.ss-list-arrow {
+  position: absolute;
+  z-index: 8;
+  width: 16px;
+  padding: 0;
+  border: 1px solid #8c959f;
+  background: #f6f8fa;
+  font-size: 9px;
+  cursor: pointer;
+}
+
+.ss-validation__dropdown {
+  position: absolute;
+  z-index: 20;
+}
diff --git a/A00_Common/spreadsheet/spreadsheet.ts b/A00_Common/spreadsheet/spreadsheet.ts
index f53be2df..ba56a878 100644
--- a/A00_Common/spreadsheet/spreadsheet.ts
+++ b/A00_Common/spreadsheet/spreadsheet.ts
@@ -74,7 +74,7 @@ export interface SpreadsheetHandle {
 
 /** 움직이는 끝(닻에서 먼 쪽) — 행열 전체면 활성 칸 쪽 */
 function farCorner(sel: Selection): { r: number; c: number } {
-  const g = sel.범위[0];
+  const g = sel.범위[sel.범위.length - 1];
   const a = sel.기준;
   const whole = (lo: number, hi: number, last: number): boolean => lo === 0 && hi === last;
   return {
@@ -222,6 +222,7 @@ export function createSpreadsheet(
     const sheet = ctx.book.시트.find((s) => s.id === sheetId);
     if (!sheet || sheetId === ctx.selection.시트) return;
     ed.commit();
+    if (ed.editing()) return; // 유효성에 막힘
     ctx.book.활성 = sheetId;
     ctx.selection = memory.get(sheetId) ?? selectCell(sheet, 0, 0);
     grid.render();
diff --git a/A00_Common/spreadsheet/spreadsheet_analysis.css b/A00_Common/spreadsheet/spreadsheet_analysis.css
new file mode 100644
index 00000000..47541bbd
--- /dev/null
+++ b/A00_Common/spreadsheet/spreadsheet_analysis.css
@@ -0,0 +1,187 @@
+/* spreadsheet_analysis.css (주인 A) — 추적 화살표 겹판 · 수식 계산 창 · 오류 ⚠ 단추 */
+
+/* 추적 화살표 — 크기 0 겹판(격자 조작을 막지 않음) */
+.ss-trace {
+  position: absolute;
+  left: 0;
+  top: 0;
+  width: 1px;
+  height: 1px;
+  overflow: visible;
+  pointer-events: none;
+}
+
+.ss-trace__line {
+  stroke-width: 1.5;
+}
+
+.ss-trace__line.is-plain,
+.ss-trace__dot.is-plain,
+.ss-trace__head.is-plain {
+  stroke: var(--color-info);
+  fill: var(--color-info);
+}
+
+.ss-trace__line.is-error,
+.ss-trace__dot.is-error,
+.ss-trace__head.is-error {
+  stroke: var(--color-danger);
+  fill: var(--color-danger);
+}
+
+.ss-trace__line.is-sheet,
+.ss-trace__dot.is-sheet,
+.ss-trace__head.is-sheet {
+  stroke: var(--color-text-body);
+  fill: var(--color-text-body);
+}
+
+.ss-trace__line.is-sheet {
+  stroke-dasharray: 4 3;
+}
+
+.ss-trace__box {
+  fill: none;
+  stroke-width: 2;
+  stroke: var(--color-info);
+}
+
+.ss-trace__box.is-error {
+  stroke: var(--color-danger);
+}
+
+.ss-trace__sheet {
+  fill: var(--color-surface);
+  stroke: var(--color-text-body);
+}
+
+/* 수식 계산 창 */
+.ss-steps {
+  position: absolute;
+  inset: 0;
+  z-index: var(--z-dropdown);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  background: rgb(0 0 0 / 18%);
+}
+
+.ss-steps__box {
+  display: flex;
+  flex-direction: column;
+  gap: var(--spacing-8);
+  min-width: 420px;
+  max-width: 90%;
+  padding: var(--spacing-12);
+  background: var(--color-surface-raised);
+  color: var(--color-text-body);
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-cards);
+  box-shadow: var(--shadow-lg);
+  font-size: 13px;
+}
+
+.ss-steps__title {
+  font-weight: 600;
+}
+
+.ss-steps__meta {
+  color: var(--color-text-secondary);
+}
+
+.ss-steps__text {
+  min-height: 60px;
+  padding: var(--spacing-8);
+  font-family: var(--font-mono, monospace);
+  white-space: pre-wrap;
+  word-break: break-all;
+  background: var(--color-canvas);
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-sm);
+}
+
+.ss-steps__foot {
+  display: flex;
+  justify-content: flex-end;
+  gap: var(--spacing-8);
+}
+
+/* 오류 ⚠ 단추 · 풍선 · 메뉴 */
+.ss-errtip {
+  position: absolute;
+  z-index: var(--z-dropdown);
+  width: 0;
+  height: 0;
+  overflow: visible;
+}
+
+.ss-errtip__btn {
+  position: absolute;
+  width: 18px;
+  height: 18px;
+  padding: 0;
+  font-size: 11px;
+  line-height: 16px;
+  cursor: pointer;
+  color: var(--color-warning);
+  background: var(--color-surface);
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-sm);
+}
+
+.ss-errtip__balloon {
+  display: none;
+  position: absolute;
+  left: 0;
+  top: 22px;
+  z-index: var(--z-dropdown);
+  width: max-content;
+  max-width: 320px;
+  padding: var(--spacing-4) var(--spacing-8);
+  font-size: 12px;
+  color: var(--color-text-body);
+  background: var(--color-surface-raised);
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-sm);
+  box-shadow: var(--shadow-lg);
+}
+
+.ss-errtip__btn:hover + .ss-errtip__balloon {
+  display: block;
+}
+
+.ss-errtip__menu {
+  position: absolute;
+  left: 0;
+  top: 22px;
+  z-index: var(--z-dropdown);
+  display: flex;
+  flex-direction: column;
+  min-width: 200px;
+  max-width: 320px;
+  padding: var(--spacing-4);
+  font-size: 13px;
+  color: var(--color-text-body);
+  background: var(--color-surface-raised);
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-sm);
+  box-shadow: var(--shadow-lg);
+}
+
+.ss-errtip__head {
+  padding: var(--spacing-4);
+  font-weight: 600;
+}
+
+.ss-errtip__item {
+  padding: var(--spacing-4);
+  text-align: left;
+  color: inherit;
+  background: none;
+  border: none;
+  cursor: pointer;
+}
+
+.ss-errtip__item:hover {
+  background: var(--color-surface-sunken);
+}
diff --git a/A00_Common/spreadsheet/spreadsheet_autosum.ts b/A00_Common/spreadsheet/spreadsheet_autosum.ts
new file mode 100644
index 00000000..defa1eda
--- /dev/null
+++ b/A00_Common/spreadsheet/spreadsheet_autosum.ts
@@ -0,0 +1,70 @@
+/* =============================================================================
+ * spreadsheet_autosum.ts  (3단계 · 주인 sub_laptop_4)
+ * 자동 합계(Alt+= · 도구 단추 Σ) — 엑셀 규칙: 활성 칸 바로 위가 숫자면 그 위 연속 숫자 칸을
+ * 위로 죽 잡고, 아니면 바로 왼쪽이 숫자면 왼쪽으로 죽 잡음. 여러 칸을 고른 채면 그 고름
+ * 안에서(활성 칸 위 또는 왼쪽만) 잡음. 아무것도 못 찾으면 빈 `=SUM()`.
+ *
+ * 잇는 법(D · E · sub7 — 지금은 하나도 안 이어짐):
+ *   1) `spreadsheet_keys.ts` 에 Alt+= 를 매핑해 `applyAutoSum(ctx)` 를 부름.
+ *   2) `spreadsheet_toolbar.ts` 에 Σ 단추를 두고 눌리면 `applyAutoSum(ctx)` 를 부름.
+ *   3) 지금은 칸에 식 글만 바로 넣음(편집기를 안 거침) — 사용자가 범위를 눈으로 고쳐 잡게 하려면
+ *      `ctx.editor.begin("=SUM(...)")` 로 편집 상태로 열고 커밋은 사용자가 Enter.
+ * ========================================================================== */
+
+import { rangeToA1, toA1 } from "./spreadsheet_address";
+import { isFrac } from "./spreadsheet_functions_math";
+import type { CellRange } from "./spreadsheet_types";
+import type { SpreadsheetContext } from "./spreadsheet_view_types";
+
+function isNumericCell(ctx: SpreadsheetContext, sheet: string, r: number, c: number): boolean {
+  if (r < 0 || c < 0) return false;
+  return isFrac(ctx.engine.value(sheet, r, c));
+}
+
+function verticalRun(
+  ctx: SpreadsheetContext,
+  sheet: string,
+  r: number,
+  c: number,
+  top: number,
+): CellRange | null {
+  if (r - 1 < top || !isNumericCell(ctx, sheet, r - 1, c)) return null;
+  let start = r - 1;
+  while (start - 1 >= top && isNumericCell(ctx, sheet, start - 1, c)) start--;
+  return { r0: start, c0: c, r1: r - 1, c1: c };
+}
+
+function horizontalRun(
+  ctx: SpreadsheetContext,
+  sheet: string,
+  r: number,
+  c: number,
+  left: number,
+): CellRange | null {
+  if (c - 1 < left || !isNumericCell(ctx, sheet, r, c - 1)) return null;
+  let start = c - 1;
+  while (start - 1 >= left && isNumericCell(ctx, sheet, r, start - 1)) start--;
+  return { r0: r, c0: start, r1: r, c1: c - 1 };
+}
+
+/** 활성 칸 기준 합산 범위를 찾음 — 없으면 null(빈 `=SUM()`). */
+export function autoSumRange(ctx: SpreadsheetContext): CellRange | null {
+  const sheet = ctx.selection.시트;
+  const { r, c } = ctx.selection.활성;
+  const sel = ctx.selection.범위[0];
+
+  if (sel && (sel.r1 > sel.r0 || sel.c1 > sel.c0)) {
+    if (r > sel.r0) return { r0: sel.r0, c0: c, r1: r - 1, c1: c };
+    if (c > sel.c0) return { r0: r, c0: sel.c0, r1: r, c1: c - 1 };
+  }
+
+  return verticalRun(ctx, sheet, r, c, 0) ?? horizontalRun(ctx, sheet, r, c, 0);
+}
+
+/** 활성 칸에 `=SUM(...)` 을 바로 넣음(칸 명령 — 편집기를 안 거침). */
+export function applyAutoSum(ctx: SpreadsheetContext): void {
+  const range = autoSumRange(ctx);
+  const { r, c } = ctx.selection.활성;
+  const 식 = range ? `SUM(${rangeToA1(range)})` : "SUM()";
+  ctx.dispatch({ 종류: "칸", 시트: ctx.selection.시트, 칸: { [toA1(r, c)]: { 식 } } });
+}
diff --git a/A00_Common/spreadsheet/spreadsheet_data_menu.ts b/A00_Common/spreadsheet/spreadsheet_data_menu.ts
new file mode 100644
index 00000000..4b023d90
--- /dev/null
+++ b/A00_Common/spreadsheet/spreadsheet_data_menu.ts
@@ -0,0 +1,213 @@
+/* =============================================================================
+ * 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.
+ * 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 { createCondFmtPanel } from "./spreadsheet_condfmt";
+import { attachFilter, toggleFilter } from "./spreadsheet_filter";
+import { createNameManagerPanel } from "./spreadsheet_names";
+import { openSortDialog, sortSelection } from "./spreadsheet_sort_dialog";
+import {
+  createValidationDropdown,
+  createValidationPanel,
+  findValidation,
+} from "./spreadsheet_validation";
+import type { KeyHooks } from "./spreadsheet_keys";
+import type { PartHandle, SpreadsheetContext } from "./spreadsheet_view_types";
+
+const TEXT = {
+  asc: "오름차순 정렬(활성 칸 열 기준)",
+  desc: "내림차순 정렬(활성 칸 열 기준)",
+  filter: "자동 필터 켜기 · 끄기(Ctrl+Shift+L · 머리 칸에서 Alt+↓ 값 목록)",
+  menu: "데이터 ▾",
+  sort: "정렬…",
+  filterItem: "자동 필터 켜기 · 끄기",
+  condfmt: "조건부 서식…",
+  validation: "데이터 유효성…",
+  names: "이름 관리…",
+  grid: "눈금선 보이기 · 숨기기",
+  close: "닫기",
+  list: "값 목록(Alt+↓)",
+};
+
+export interface DataMenu {
+  /** 수식 입력줄 앞에 둘 단추들 */
+  buttons: HTMLElement[];
+  keys: Pick<KeyHooks, "filter" | "dropdown">;
+  part: PartHandle;
+}
+
+export function mountDataMenu(ctx: SpreadsheetContext, back: () => void): DataMenu {
+  const filter = attachFilter(ctx);
+  const menu = createMapContextMenu("ss");
+  ctx.root.append(menu.element);
+  let closeSort: (() => void) | null = null;
+
+  const button = (text: string, title: string, run: (b: HTMLElement) => void, keep = false) => {
+    const b = el("button", { className: "ss-brush", text, attrs: { type: "button", title } });
+    b.addEventListener("click", () => {
+      run(b);
+      if (!keep) back();
+    });
+    return b;
+  };
+
+  // ── 패널 창(조건부 서식 · 유효성 · 이름) — 한 번에 하나 ─────────────────────
+  const title = el("span", { className: "ss-dialog__title" });
+  const body = el("div", { className: "ss-dialog__body" });
+  const shut = el("button", {
+    className: "ss-find__btn",
+    text: "×",
+    attrs: { type: "button", title: TEXT.close },
+  });
+  const dialog = el("div", {
+    className: "ss-dialog",
+    attrs: { hidden: "" },
+    children: [el("div", { className: "ss-dialog__head", children: [title, shut] }), body],
+  });
+  ctx.root.append(dialog);
+  let panel: PartHandle | null = null;
+  const closePanel = (): void => {
+    panel?.destroy();
+    panel = null;
+    body.replaceChildren();
+    dialog.setAttribute("hidden", "");
+  };
+  shut.addEventListener("click", () => (closePanel(), back()));
+  dialog.addEventListener("keydown", (e) => {
+    if (e.key !== "Escape") return;
+    e.stopPropagation();
+    closePanel();
+    back();
+  });
+  function openPanel(name: string, make: (c: SpreadsheetContext) => PartHandle): void {
+    closePanel();
+    panel = make(ctx);
+    title.textContent = name.replace("…", "");
+    if (panel.root) body.append(panel.root);
+    dialog.removeAttribute("hidden");
+  }
+
+  function openMenu(anchor: HTMLElement): void {
+    const r = anchor.getBoundingClientRect();
+    const items: [string, () => void][] = [
+      [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.grid, () => (toggleGridlines(), back())],
+    ];
+    if (!ctx.readOnly) menu.open(r.left, r.bottom, items);
+  }
+
+  function toggleGridlines(): void {
+    const s = ctx.sheet();
+    ctx.dispatch({ 종류: "눈금선", 시트: s.id, 보임: s.보기?.눈금선 === false });
+  }
+
+  // ── 유효성 목록 — ▼ 단추 · Alt+↓ ─────────────────────────────────────────
+  let drop: HTMLElement | null = null;
+  const closeDrop = (): void => {
+    drop?.remove();
+    drop = null;
+  };
+  const arrow = el("button", {
+    className: "ss-list-arrow",
+    text: "▼",
+    attrs: { type: "button", hidden: "", title: TEXT.list },
+  });
+  arrow.addEventListener("mousedown", (e) => e.preventDefault());
+  arrow.addEventListener("click", () => openList());
+  ctx.root.append(arrow);
+  /** 칸 자리(부품 뿌리 기준) */
+  const at = (r: number, c: number) => {
+    const { box } = ctx.grid.editorSlot(r, c);
+    const g = ctx.grid.root.getBoundingClientRect();
+    const o = ctx.root.getBoundingClientRect();
+    return { x: box.x + g.left - o.left, y: box.y + g.top - o.top, w: box.w, h: box.h };
+  };
+  function openList(): boolean {
+    const { r, c } = ctx.selection.활성;
+    const rule = findValidation(ctx.sheet(), r, c);
+    if (ctx.readOnly || !rule) return false;
+    closeDrop();
+    drop = createValidationDropdown(ctx, r, c, rule, (value) => {
+      closeDrop();
+      const key = toA1(r, c);
+      const n = Number(value);
+      const 값 = value !== "" && Number.isFinite(n) ? n : value;
+      const 서식 = ctx.sheet().칸[key]?.서식;
+      const cell = 서식 === undefined ? { 값 } : { 값, 서식 };
+      ctx.dispatch({ 종류: "칸", 시트: ctx.selection.시트, 칸: { [key]: cell } });
+      back();
+    });
+    if (!drop) return false;
+    const p = at(r, c);
+    drop.style.left = `${p.x}px`; // cellBox(스크롤 전 내용 좌표) 자리를 화면 자리로 고침
+    drop.style.top = `${p.y + p.h}px`;
+    ctx.root.append(drop);
+    return true;
+  }
+  const onOutside = (e: MouseEvent): void => {
+    if (drop && !drop.contains(e.target as Node) && e.target !== arrow) closeDrop();
+  };
+  document.addEventListener("mousedown", onOutside, true);
+
+  const buttons = ctx.readOnly
+    ? []
+    : [
+        button("↑", TEXT.asc, () => sortSelection(ctx, false)),
+        button("↓", TEXT.desc, () => sortSelection(ctx, true)),
+        button("필터", TEXT.filter, () => toggleFilter(ctx)),
+        button(TEXT.menu, TEXT.menu, openMenu, true),
+      ];
+
+  return {
+    buttons,
+    keys: {
+      filter: () => toggleFilter(ctx),
+      dropdown() {
+        const f = ctx.sheet().필터;
+        const g = f && parseRange(f.범위);
+        const { r, c } = ctx.selection.활성;
+        if (g && r === g.r0 && c >= g.c0 && c <= g.c1) return (filter.open(c), true);
+        return openList();
+      },
+    },
+    part: {
+      root: null,
+      refresh() {
+        filter.refresh();
+        panel?.refresh();
+        closeDrop();
+        const { r, c } = ctx.selection.활성;
+        const list = !ctx.readOnly && findValidation(ctx.sheet(), r, c)?.규칙.종류 === "목록";
+        arrow.hidden = !list || ctx.editor.editing();
+        if (!list) return;
+        const p = at(r, c);
+        arrow.style.left = `${p.x + p.w + 1}px`;
+        arrow.style.top = `${p.y}px`;
+        arrow.style.height = `${p.h}px`;
+      },
+      destroy() {
+        document.removeEventListener("mousedown", onOutside, true);
+        closeSort?.();
+        closePanel();
+        closeDrop();
+        filter.destroy();
+        menu.element.remove();
+        dialog.remove();
+        arrow.remove();
+        buttons.forEach((b) => b.remove());
+      },
+    },
+  };
+}
diff --git a/A00_Common/spreadsheet/spreadsheet_editor.ts b/A00_Common/spreadsheet/spreadsheet_editor.ts
index ed3b9e90..5d5736b8 100644
--- a/A00_Common/spreadsheet/spreadsheet_editor.ts
+++ b/A00_Common/spreadsheet/spreadsheet_editor.ts
@@ -8,12 +8,14 @@
  * 수식 입력줄(방향키가 글자 사이를 옮김). F2 가 둘을 바꿈.
  * ========================================================================== */
 
-import { el } from "@ui/ui_template_elements";
+import { el, showToast } from "@ui/ui_template_elements";
 import { moveFormula } from "./spreadsheet_refshift";
 import { colName, parseA1, parseRange, rangeToA1, toA1 } from "./spreadsheet_address";
 import { funcHelp, suggestFunctions, type FuncHelp } from "./spreadsheet_func_help";
+import { defineName, resolveName } from "./spreadsheet_names";
 import { tokenize } from "./spreadsheet_parser";
 import { cellsOf, move, selectCell } from "./spreadsheet_selection";
+import { checkValue, findValidation } from "./spreadsheet_validation";
 import type { Cell, CellAddress, CellStyle, Sheet } from "./spreadsheet_types";
 import type {
   CellBox,
@@ -329,10 +331,12 @@ export function createEditor(ctx: SpreadsheetContext): Editor {
     focus();
   }
 
-  function write(cells: CellAddress[], value: string, from: CellAddress): void {
-    if (!st) return;
+  /** 칸에 적음 — 유효성(sub4) 「막음」 을 어기면 안 적고 false(편집 그대로 · 엑셀처럼 다시 치게) */
+  function write(cells: CellAddress[], value: string, from: CellAddress): boolean {
+    if (!st) return true;
     const sheet = sheetOf(st.sheet);
     const out: Record<string, Cell | null> = {};
+    const warn = new Set<string>();
     for (const a of cells) {
       let v = value;
       if (v.length > 1 && v[0] === "=" && (a.r !== from.r || a.c !== from.c))
@@ -340,21 +344,29 @@ export function createEditor(ctx: SpreadsheetContext): Editor {
       const key = toA1(a.r, a.c);
       const next = textToCell(v, sheet.칸[key]);
       if (next === null && !sheet.칸[key]) continue;
+      const rule = next?.값 !== undefined ? findValidation(sheet, a.r, a.c) : undefined;
+      const check = rule && checkValue(rule, next!.값!);
+      if (check && !check.ok) {
+        if (check.어기면 === "막음") return (showToast(check.메시지, "error"), false);
+        warn.add(check.메시지);
+      }
       out[key] = next;
     }
+    for (const m of warn) showToast(m, "warning");
     if (Object.keys(out).length) ctx.dispatch({ 종류: "칸", 시트: sheet.id, 칸: out });
+    return true;
   }
 
   function commit(): void {
     if (!st) return;
     const value = text();
-    if (value !== st.original) write([st.at], value, st.at);
+    if (value !== st.original && !write([st.at], value, st.at)) return;
     end();
   }
 
   function commitAll(): void {
     if (!st) return;
-    write(cellsOf(sheetOf(st.sheet), ctx.selection), text(), st.at);
+    if (!write(cellsOf(sheetOf(st.sheet), ctx.selection), text(), st.at)) return;
     end();
   }
 
@@ -441,6 +453,19 @@ export function createEditor(ctx: SpreadsheetContext): Editor {
     focus();
   });
 
+  /** 이름 상자(sub4) — 있는 이름이면 그 범위로 · 없으면 지금 고름에 이름을 붙임(엑셀) */
+  function nameBox(name: string): void {
+    const hit = resolveName(ctx.book, ctx.selection.시트, name);
+    if (hit) {
+      if (hit.시트 !== ctx.selection.시트) ctx.showSheet(hit.시트);
+      const at = { r: hit.범위.r0, c: hit.범위.c0 };
+      return ctx.select({ 시트: hit.시트, 범위: [hit.범위], 활성: at, 기준: { ...at } }, true);
+    }
+    const why = ctx.readOnly ? null : defineName(ctx, name, ctx.selection.범위[0]);
+    if (why) showToast(why, "error");
+    sync();
+  }
+
   function goTo(value: string): void {
     const bang = value.lastIndexOf("!");
     let sheet = ctx.sheet();
@@ -454,7 +479,7 @@ export function createEditor(ctx: SpreadsheetContext): Editor {
     const body = value.slice(bang + 1).replace(/\$/g, "");
     const one = parseA1(body);
     const g = parseRange(body);
-    if (!g) return sync();
+    if (!g) return nameBox(value.trim());
     if (one) return ctx.select(selectCell(sheet, one.r, one.c), true);
     const at = { r: g.r0, c: g.c0 };
     ctx.select({ 시트: sheet.id, 범위: [g], 활성: at, 기준: { ...at } }, true);
diff --git a/A00_Common/spreadsheet/spreadsheet_errcheck.ts b/A00_Common/spreadsheet/spreadsheet_errcheck.ts
new file mode 100644
index 00000000..b4642234
--- /dev/null
+++ b/A00_Common/spreadsheet/spreadsheet_errcheck.ts
@@ -0,0 +1,193 @@
+/* =============================================================================
+ * spreadsheet_errcheck.ts  (주인 A)
+ * 오류 검사(엑셀 초록 세모) — 칸마다 까닭을 냄: 순환 참조 · 식 결과가 오류(#DIV/0! 등) · 숫자처럼 보이는 글.
+ * 활성 칸에 까닭이 있으면 칸 왼쪽에 ⚠ 단추 · 올리면 까닭 풍선 · 누르면 메뉴(숫자로 변환 · 계산 단계 보기 ·
+ * 선행 참조 추적 · 오류 무시). 「오류 무시」는 이 화면 동안만(문서에 안 적음).
+ *
+ * 잇는 법(C · sub6 · D · sub7):
+ *   · 부품 붙이기: `const tip = attachErrorTip(ctx, trace?)` — ⚠ 단추를 격자 overlay(editorSlot 층)에 얹음.
+ *     grid.render() · 고름 바뀜 뒤마다 `tip.refresh()`. `trace`(spreadsheet_trace 의 손잡이)를 주면 메뉴에 「선행 참조 추적」.
+ *   · 격자(C): 보이는 칸마다 `tip.warning(r, c)` 가 null 이 아니면 칸 왼쪽 위에 초록 세모(6px · `--color-success`).
+ *     시트 전체를 훑지 말고 그리는 칸만 물음(값 하나 · 칸 하나 읽는 값싼 부름).
+ * ========================================================================== */
+
+import { el } from "@ui/ui_template_elements";
+import { currentLanguageIndex } from "@ui/ui_template_locale";
+import { toA1 } from "./spreadsheet_address";
+import { isError } from "./spreadsheet_eval";
+import { openEvalSteps } from "./spreadsheet_eval_steps";
+import type { TraceHandle } from "./spreadsheet_trace";
+import type { CalcEngine, Cell, Workbook } from "./spreadsheet_types";
+import type { PartHandle, SpreadsheetContext } from "./spreadsheet_view_types";
+import "./spreadsheet_analysis.css";
+
+export type WarningKind = "순환" | "오류" | "글숫자";
+
+export interface CellWarning {
+  종류: WarningKind;
+  까닭: string;
+}
+
+/** 엑셀 오류 값 뜻(엔진 까닭이 없을 때) */
+const MEANING: Record<string, [string, string]> = {
+  "#DIV/0!": ["0 으로 나눔", "Divide by zero"],
+  "#VALUE!": ["값의 종류가 맞지 않음", "Wrong type of value"],
+  "#REF!": ["지워진 칸을 가리킴", "Invalid cell reference"],
+  "#NAME?": ["모르는 이름 · 함수", "Unrecognized name"],
+  "#N/A": ["찾는 값이 없음", "Value not available"],
+  "#NUM!": ["수가 맞지 않음", "Invalid number"],
+  "#NULL!": ["겹치지 않는 범위", "Ranges do not intersect"],
+};
+
+const TEXT = {
+  Cycle: ["순환 참조", "Circular reference"],
+  TextNumber: ["숫자가 글로 저장됨", "Number stored as text"],
+  Convert: ["숫자로 변환", "Convert to number"],
+  Steps: ["계산 단계 보기", "Show calculation steps"],
+  Trace: ["선행 참조 추적", "Trace precedents"],
+  Ignore: ["오류 무시", "Ignore error"],
+};
+const t = (k: keyof typeof TEXT) => TEXT[k][currentLanguageIndex] ?? TEXT[k][0];
+
+/** 숫자로 읽히는 글(앞뒤 빈칸 · 천 단위 쉼표 · 지수 허용) */
+const NUMBER_LIKE = /^[+-]?(\d{1,3}(,\d{3})+|\d+)?(\.\d+)?(e[+-]?\d+)?$/i;
+
+export function numberLike(text: string): number | null {
+  const s = text.trim();
+  if (!/\d/.test(s) || !NUMBER_LIKE.test(s)) return null;
+  const n = Number(s.replace(/,/g, ""));
+  return Number.isFinite(n) ? n : null;
+}
+
+/** 칸 하나 까닭 — 없으면 null */
+export function cellWarning(
+  book: Workbook,
+  engine: CalcEngine,
+  sheet: string,
+  r: number,
+  c: number,
+): CellWarning | null {
+  const cell: Cell | undefined = book.시트.find((s) => s.id === sheet)?.칸[toA1(r, c)];
+  if (!cell) return null;
+  if (cell.식 !== undefined) {
+    const v = engine.value(sheet, r, c);
+    if (!isError(v)) return null;
+    if (v.error === "#CYCLE!") return { 종류: "순환", 까닭: v.why ?? t("Cycle") };
+    const m = MEANING[v.error];
+    const head = m ? `${v.error} ${m[currentLanguageIndex] ?? m[0]}` : v.error;
+    return { 종류: "오류", 까닭: v.why ? `${v.error} ${v.why}` : head };
+  }
+  if (typeof cell.값 === "string" && numberLike(cell.값) !== null)
+    return { 종류: "글숫자", 까닭: t("TextNumber") };
+  return null;
+}
+
+export interface ErrorTipHandle extends PartHandle {
+  /** 격자 세모용 — 「오류 무시」한 칸은 null */
+  warning(r: number, c: number): CellWarning | null;
+}
+
+export function attachErrorTip(ctx: SpreadsheetContext, trace?: TraceHandle): ErrorTipHandle {
+  const layer = el("div", { className: "ss-errtip" });
+  const ignored = new Set<string>();
+  let menu: HTMLElement | null = null;
+
+  const warning = (r: number, c: number) =>
+    ignored.has(`${ctx.sheet().id}!${toA1(r, c)}`)
+      ? null
+      : cellWarning(ctx.book, ctx.engine, ctx.sheet().id, r, c);
+
+  function closeMenu() {
+    menu?.remove();
+    menu = null;
+    document.removeEventListener("mousedown", onOutside, true);
+  }
+  const onOutside = (ev: MouseEvent) => {
+    if (menu && !layer.contains(ev.target as Node)) closeMenu();
+  };
+
+  /** 고른 칸 중 글숫자를 모두 수로(서식은 그대로) */
+  function convert() {
+    const s = ctx.sheet();
+    const cells: Record<string, Cell> = {};
+    for (const g of ctx.selection.범위)
+      for (let r = g.r0; r <= g.r1; r++)
+        for (let c = g.c0; c <= g.c1; c++) {
+          const a1 = toA1(r, c);
+          const cell = s.칸[a1];
+          const n =
+            typeof cell?.값 === "string" && cell.식 === undefined ? numberLike(cell.값) : null;
+          if (n !== null) cells[a1] = { ...cell, 값: n };
+        }
+    if (Object.keys(cells).length) ctx.dispatch({ 종류: "칸", 시트: s.id, 칸: cells });
+  }
+
+  function place() {
+    closeMenu();
+    const { r, c } = ctx.selection.활성;
+    const { layer: host, box } = ctx.grid.editorSlot(r, c);
+    if (layer.parentElement !== host) host.append(layer);
+    const w = warning(r, c);
+    const v = ctx.grid.visibleRange();
+    if (!w || !box.w || r < v.r0 || r > v.r1 || c < v.c0 || c > v.c1) {
+      layer.replaceChildren();
+      return;
+    }
+    const a = host.getBoundingClientRect();
+    const g = ctx.grid.root.getBoundingClientRect();
+    layer.style.left = `${box.x - (a.left - g.left) - 20}px`;
+    layer.style.top = `${box.y - (a.top - g.top)}px`;
+    const btn = el("button", {
+      className: "ss-errtip__btn",
+      text: "⚠",
+      attrs: { type: "button", "aria-label": w.까닭 },
+    });
+    const balloon = el("div", { className: "ss-errtip__balloon", text: w.까닭 });
+    btn.addEventListener("mousedown", (ev) => ev.stopPropagation());
+    btn.addEventListener("click", () => (menu ? closeMenu() : openMenu(w, r, c)));
+    layer.replaceChildren(btn, balloon);
+  }
+
+  function openMenu(w: CellWarning, r: number, c: number) {
+    const item = (label: string, run: () => void) => {
+      const b = el("button", {
+        className: "ss-errtip__item",
+        text: label,
+        attrs: { type: "button" },
+      });
+      b.addEventListener("click", () => {
+        closeMenu();
+        run();
+      });
+      return b;
+    };
+    const items: HTMLElement[] = [el("div", { className: "ss-errtip__head", text: w.까닭 })];
+    if (w.종류 === "글숫자" && !ctx.readOnly) items.push(item(t("Convert"), convert));
+    if (w.종류 !== "글숫자") items.push(item(t("Steps"), () => openEvalSteps(ctx)));
+    if (w.종류 !== "글숫자" && trace) items.push(item(t("Trace"), () => trace.precedents()));
+    items.push(
+      item(t("Ignore"), () => {
+        ignored.add(`${ctx.sheet().id}!${toA1(r, c)}`);
+        ctx.grid.render();
+        place();
+      }),
+    );
+    menu = el("div", { className: "ss-errtip__menu", attrs: { role: "menu" }, children: items });
+    layer.append(menu);
+    document.addEventListener("mousedown", onOutside, true);
+  }
+
+  const onScroll = () => place();
+  ctx.grid.root.addEventListener("scroll", onScroll, true);
+  place();
+  return {
+    root: layer,
+    refresh: place,
+    warning,
+    destroy() {
+      closeMenu();
+      ctx.grid.root.removeEventListener("scroll", onScroll, true);
+      layer.remove();
+    },
+  };
+}
diff --git a/A00_Common/spreadsheet/spreadsheet_eval_steps.ts b/A00_Common/spreadsheet/spreadsheet_eval_steps.ts
new file mode 100644
index 00000000..15750ba8
--- /dev/null
+++ b/A00_Common/spreadsheet/spreadsheet_eval_steps.ts
@@ -0,0 +1,261 @@
+/* =============================================================================
+ * spreadsheet_eval_steps.ts  (주인 A)
+ * 수식 계산 단계 보기(엑셀 [수식 계산] 창) — 식을 왼쪽부터 한 마디씩 값으로 바꿔 보여 줌.
+ * 엑셀 규칙: 칸 참조 → 값(빈 칸은 0 · 글은 따옴표) · 연산 · 함수는 인자가 다 값이 된 뒤 · 범위는 함수가 통째로 풂 ·
+ * IF · IFERROR · CHOOSE 류는 첫 인자만 먼저 풀고 고른 쪽은 함수 한 걸음으로 · ROW(A1) 같은 참조 인자는 그대로.
+ * 마디 값은 늘 엔진 풀이(`evalSafe`)로 냄 — 보이는 글은 보여 주기만.
+ *
+ * 잇는 법(D · sub7):
+ *   · 도구 모음 [수식 분석] 「수식 계산」 → `openEvalSteps(ctx)` — 활성 칸 식의 창을 `ctx.root` 에 띄우고 닫는 함수를 돌려줌.
+ *   · 식 없는 칸이면 토스트로 알리고 창을 안 띄움. 들어가기(참조 칸 식 속으로)는 아직 없음.
+ * ========================================================================== */
+
+import { createButton, el, showToast } from "@ui/ui_template_elements";
+import { currentLanguageIndex } from "@ui/ui_template_locale";
+import { parseA1, quoteSheet, toA1 } from "./spreadsheet_address";
+import { isError, isRange, numberText } from "./spreadsheet_eval";
+import type { PlacedRange } from "./spreadsheet_eval";
+import { evalSafe } from "./spreadsheet_graph";
+import { formulaToText, parseFormula } from "./spreadsheet_parser";
+import type {
+  CalcEngine,
+  CellRange,
+  EvalContext,
+  FormulaNode,
+  Scalar,
+  Workbook,
+} from "./spreadsheet_types";
+import type { SpreadsheetContext } from "./spreadsheet_view_types";
+import "./spreadsheet_analysis.css";
+
+/** 한 걸음 — 글과 다음에 풀 곳(밑줄 · 글 안 [시작, 끝)) */
+export interface EvalStep {
+  글: string;
+  밑줄: [number, number] | null;
+}
+
+/** 첫 인자만 먼저 풂 */
+const LAZY = new Set(["IF", "IFS", "IFERROR", "IFNA", "CHOOSE", "SWITCH"]);
+/** 칸 참조 인자를 값으로 안 바꿈 */
+const REF_ARGS = new Set([
+  "ROW",
+  "COLUMN",
+  "ROWS",
+  "COLUMNS",
+  "OFFSET",
+  "INDEX",
+  "ISREF",
+  "ISBLANK",
+  "CELL",
+  "ISFORMULA",
+  "FORMULATEXT",
+  "SUMIF",
+  "SUMIFS",
+  "COUNTIF",
+  "COUNTIFS",
+  "AVERAGEIF",
+  "AVERAGEIFS",
+  "COUNTBLANK",
+]);
+
+/** 푸는 차례(왼쪽 먼저 · 아래 먼저) */
+function order(node: FormulaNode, out: FormulaNode[], refArg = false): void {
+  switch (node.type) {
+    case "cell":
+      if (!refArg) out.push(node);
+      return;
+    case "name":
+      out.push(node);
+      return;
+    case "unary":
+      if (node.op !== "%" && node.arg.type === "number") return; // -5 는 글 그대로
+      order(node.arg, out);
+      out.push(node);
+      return;
+    case "binary":
+      order(node.left, out);
+      order(node.right, out);
+      out.push(node);
+      return;
+    case "call": {
+      const args = LAZY.has(node.name) ? node.args.slice(0, 1) : node.args;
+      for (const a of args) order(a, out, REF_ARGS.has(node.name));
+      out.push(node);
+    }
+  }
+}
+
+export function valueText(v: Scalar): string {
+  if (v === null) return "0";
+  if (typeof v === "string") return `"${v.replace(/"/g, '""')}"`;
+  if (typeof v === "boolean") return v ? "TRUE" : "FALSE";
+  if (isError(v)) return v.error;
+  return numberText(v);
+}
+
+/** 엔진 없이 쓸 풀이 문맥 — 칸 값은 엔진에서 · 범위는 값 든 끝까지(엔진과 같게) */
+function contextFor(book: Workbook, engine: CalcEngine, sheet: string, r: number, c: number) {
+  const ext = new Map<string, { r: number; c: number }>();
+  const extent = (id: string) => {
+    let e = ext.get(id);
+    if (!e) {
+      e = { r: 0, c: 0 };
+      for (const [a1, cell] of Object.entries(book.시트.find((s) => s.id === id)?.칸 ?? {})) {
+        const at = cell.식 !== undefined || cell.값 !== undefined ? parseA1(a1) : null;
+        if (at) e = { r: Math.max(e.r, at.r), c: Math.max(e.c, at.c) };
+      }
+      ext.set(id, e);
+    }
+    return e;
+  };
+  const ctx: EvalContext = {
+    sheet,
+    r,
+    c,
+    cell: (s, rr, cc) => engine.value(s, rr, cc),
+    range(s, rg: CellRange): PlacedRange {
+      const e = extent(s);
+      const r1 = Math.min(rg.r1, Math.max(rg.r0, e.r));
+      const c1 = Math.min(rg.c1, Math.max(rg.c0, e.c));
+      return {
+        kind: "range",
+        rows: r1 - rg.r0 + 1,
+        cols: c1 - rg.c0 + 1,
+        at: (i, j) => engine.value(s, rg.r0 + i, rg.c0 + j),
+        ...rg,
+      };
+    },
+    sheetId: (name) =>
+      book.시트.find((s) => s.이름.toLowerCase() === name.toLowerCase())?.id ?? null,
+  };
+  return ctx;
+}
+
+/** 칸 식의 모든 걸음(첫 글 → … → 값) · 식이 없으면 null */
+export function evalSteps(
+  book: Workbook,
+  engine: CalcEngine,
+  sheet: string,
+  r: number,
+  c: number,
+): EvalStep[] | null {
+  const text = book.시트.find((s) => s.id === sheet)?.칸[toA1(r, c)]?.식;
+  if (text === undefined) return null;
+  const p = parseFormula(text);
+  if (!p.ok)
+    return [
+      { 글: text, 밑줄: null },
+      { 글: valueText(engine.value(sheet, r, c)), 밑줄: null },
+    ];
+  const ctx = contextFor(book, engine, sheet, r, c);
+  const nodes: FormulaNode[] = [];
+  order(p.node, nodes);
+  // 식 전체가 범위(`=A1:A3`)면 마지막 걸음으로 엔진 값(암묵 교차)
+  if (nodes[nodes.length - 1] !== p.node && p.node.type === "range") nodes.push(p.node);
+  const vals = new Map<FormulaNode, Scalar>();
+  const steps: FormulaNode[] = [];
+  for (const n of nodes) {
+    if (n === p.node) vals.set(n, engine.value(sheet, r, c));
+    else {
+      const v = evalSafe(n, ctx);
+      if (isRange(v)) continue; // 범위 값(INDEX 등)은 글 그대로
+      vals.set(n, v);
+    }
+    steps.push(n);
+  }
+  const done = new Map<FormulaNode, string>();
+  const out: EvalStep[] = [];
+  for (let i = 0; i <= steps.length; i++) {
+    const raw = formulaToText(p.node, (n) => done.get(n), steps[i]);
+    const a = raw.indexOf("\u0001");
+    const b = raw.indexOf("\u0002");
+    out.push(
+      a < 0
+        ? { 글: raw, 밑줄: null }
+        : { 글: raw.replace(/[\u0001\u0002]/g, ""), 밑줄: [a, b - 1] },
+    );
+    if (i < steps.length) done.set(steps[i], valueText(vals.get(steps[i]) ?? null));
+  }
+  return out;
+}
+
+// ── 창 ──────────────────────────────────────────────────────────────────────
+
+const TEXT = {
+  Title: ["수식 계산", "Evaluate Formula"],
+  Ref: ["참조", "Reference"],
+  Hint: [
+    "밑줄 친 식의 값을 보려면 [계산] 을 누름",
+    "To show the result of the underlined expression, click Evaluate.",
+  ],
+  Eval: ["계산", "Evaluate"],
+  Restart: ["다시 시작", "Restart"],
+  Close: ["닫기", "Close"],
+  NoFormula: ["식이 없는 칸", "The cell has no formula"],
+};
+const t = (k: keyof typeof TEXT) => TEXT[k][currentLanguageIndex] ?? TEXT[k][0];
+
+export function openEvalSteps(ctx: SpreadsheetContext): () => void {
+  const sheet = ctx.sheet();
+  const { r, c } = ctx.selection.활성;
+  const steps = evalSteps(ctx.book, ctx.engine, sheet.id, r, c);
+  if (!steps) {
+    showToast(t("NoFormula"), "info");
+    return () => {};
+  }
+  let i = 0;
+  const view = el("div", { className: "ss-steps__text", attrs: { "aria-live": "polite" } });
+  const next = createButton({
+    label: t("Eval"),
+    onClick: () => go(i + 1 < steps.length ? i + 1 : 0),
+  });
+  const box = el("div", {
+    className: "ss-steps__box",
+    attrs: { role: "dialog", "aria-label": t("Title") },
+  });
+  const shade = el("div", { className: "ss-steps", children: [box] });
+
+  function go(to: number) {
+    i = to;
+    const s = steps![i];
+    if (!s.밑줄) view.replaceChildren(s.글);
+    else {
+      const [a, b] = s.밑줄;
+      view.replaceChildren(s.글.slice(0, a), el("u", { text: s.글.slice(a, b) }), s.글.slice(b));
+    }
+    next.textContent = i + 1 < steps!.length ? t("Eval") : t("Restart");
+  }
+  const close = () => {
+    shade.remove();
+    document.removeEventListener("keydown", onKey, true);
+  };
+  const onKey = (ev: KeyboardEvent) => {
+    if (ev.key === "Escape") close();
+    else if (ev.key === "Enter") next.click();
+    else return;
+    ev.preventDefault();
+    ev.stopPropagation();
+  };
+
+  box.append(
+    el("div", { className: "ss-steps__title", text: t("Title") }),
+    el("div", {
+      className: "ss-steps__meta",
+      text: `${t("Ref")}: ${ctx.book.시트.length > 1 ? `${quoteSheet(sheet.이름)}!` : ""}${toA1(r, c)}`,
+    }),
+    view,
+    el("div", { className: "ss-steps__meta", text: t("Hint") }),
+    el("div", {
+      className: "ss-steps__foot",
+      children: [next, createButton({ label: t("Close"), variant: "ghost", onClick: close })],
+    }),
+  );
+  shade.addEventListener("mousedown", (ev) => {
+    if (ev.target === shade) close();
+  });
+  document.addEventListener("keydown", onKey, true);
+  go(0);
+  ctx.root.append(shade);
+  next.focus();
+  return close;
+}
diff --git a/A00_Common/spreadsheet/spreadsheet_extras.ts b/A00_Common/spreadsheet/spreadsheet_extras.ts
index 47bc79f1..863a8d27 100644
--- a/A00_Common/spreadsheet/spreadsheet_extras.ts
+++ b/A00_Common/spreadsheet/spreadsheet_extras.ts
@@ -1,34 +1,30 @@
 /* =============================================================================
  * spreadsheet_extras.ts  (주인 D)
  * 2단계 부품 잇기(sub1 파일들의 「잇는 법」) — 찾기 패널 · 메모 풍선(마우스 올림) · 메모 편집(Shift+F2) ·
- * 서식 붓(수식 입력줄 앞 단추 · 두 번 누르면 계속 · Esc 끔) · 골라 붙여넣기(Ctrl+Shift+V → 값만 · 서식만 · 수식만) ·
- * 도구 모음을 누른 뒤 초점을 격자로 되돌림 · 정렬(↑ ↓ 정렬…) · 자동 필터(단추 · Ctrl+Shift+L · Alt+↓).
+ * 셀 서식 창(Ctrl+1) · 서식 붓(수식 입력줄 앞 단추 · 두 번 누르면 계속 · Esc 끔) · 골라 붙여넣기(Ctrl+Shift+V → 값만 · 서식만 · 수식만) ·
+ * 도구 모음을 누른 뒤 초점을 격자로 되돌림 · 데이터 단추 · 메뉴는 `spreadsheet_data_menu.ts`.
  * 빨간 세모는 C 격자 · 우클릭 [메모 …] 는 E 메뉴 몫(브레인 배정).
  * ========================================================================== */
 
 import { el } from "@ui/ui_template_elements";
-import { parseRange } from "./spreadsheet_address";
 import { parseClipboard } from "./spreadsheet_clipboard";
 import { attachComments, getComment, setComment } from "./spreadsheet_comments";
+import { mountDataMenu } from "./spreadsheet_data_menu";
 import type { Editor } from "./spreadsheet_editor";
-import { attachFilter, toggleFilter } from "./spreadsheet_filter";
 import { mountFindPanel } from "./spreadsheet_find_panel";
+import { openFormatDialog } from "./spreadsheet_format_dialog";
 import { createFormatPainter } from "./spreadsheet_format_painter";
 import type { KeyHooks } from "./spreadsheet_keys";
 import type { MouseHooks } from "./spreadsheet_mouse";
 import { pasteSpecial, type PasteSpecialMode } from "./spreadsheet_paste_special";
-import { openSortDialog, sortSelection } from "./spreadsheet_sort_dialog";
 import type { PartHandle, SpreadsheetContext } from "./spreadsheet_view_types";
 
 const TEXT = {
+  format: "셀 서식(Ctrl+1)",
   painter: "서식 붓 — 한 번 누르면 한 번 · 두 번 누르면 Esc 까지 계속",
   pasteTitle: "골라 붙여넣기",
   modes: { 값: "값만", 서식: "서식만", 수식: "수식만" } as Record<PasteSpecialMode, string>,
   memo: "메모 — Ctrl+Enter 또는 밖을 누르면 적용 · Esc 취소",
-  sortAsc: "오름차순 정렬(활성 칸 열 기준)",
-  sortDesc: "내림차순 정렬(활성 칸 열 기준)",
-  sortDialog: "정렬 — 기준 여럿 · 머리 행",
-  filter: "자동 필터 켜기 · 끄기(Ctrl+Shift+L · 머리 칸에서 Alt+↓ 값 목록)",
 };
 
 export interface Extras {
@@ -113,34 +109,29 @@ export function attachExtras(
     showBrush();
     back();
   });
-  if (!ctx.readOnly) ed.bar.prepend(brush);
-
-  // ── 정렬 · 필터(sub3) — 수식 입력줄 앞 데이터 단추 ───────────────────────
-  const filter = attachFilter(ctx);
-  let closeSort: (() => void) | null = null;
-  const dataButton = (text: string, title: string, run: () => void, dialog = false) => {
-    const b = el("button", { className: "ss-brush", text, attrs: { type: "button", title } });
-    b.addEventListener("click", () => {
-      run();
-      if (!dialog) back();
+  // 셀 서식 창 — Ctrl+1 을 브라우저 · ORCA 가 가로챌 때 누를 자리
+  const fmt = el("button", {
+    className: "ss-brush",
+    text: "서식…",
+    attrs: { type: "button", title: TEXT.format },
+  });
+  /** 창이 닫히면(확인 · 취소) 초점을 격자로 */
+  function openFormat(): void {
+    if (ctx.readOnly) return;
+    openFormatDialog(ctx);
+    const watch = new MutationObserver(() => {
+      if (document.querySelector(".ss-fmtdlg")) return;
+      watch.disconnect();
+      back();
     });
-    return b;
-  };
-  const data = [
-    dataButton("↑", TEXT.sortAsc, () => sortSelection(ctx, false)),
-    dataButton("↓", TEXT.sortDesc, () => sortSelection(ctx, true)),
-    dataButton(
-      "정렬…",
-      TEXT.sortDialog,
-      () => {
-        closeSort?.();
-        closeSort = openSortDialog(ctx);
-      },
-      true,
-    ),
-    dataButton("필터", TEXT.filter, () => toggleFilter(ctx)),
-  ];
-  if (!ctx.readOnly) brush.after(...data);
+    watch.observe(document.body, { childList: true });
+  }
+  fmt.addEventListener("click", openFormat);
+  if (!ctx.readOnly) ed.bar.prepend(fmt, brush);
+
+  // ── 데이터 단추 · 메뉴(정렬 · 필터 · 조건부 서식 · 유효성 · 이름 · 눈금선) ─────────
+  const data = mountDataMenu(ctx, back);
+  brush.after(...data.buttons);
 
   // ── 골라 붙여넣기 ─────────────────────────────────────────────────────────
   let armed = false;
@@ -201,14 +192,13 @@ export function attachExtras(
     root: null,
     refresh: () => showBrush(),
     destroy() {
-      closeSort?.();
-      data.forEach((b) => b.remove());
       ctx.root.removeEventListener("paste", onPaste, true);
       toolbarRoot?.removeEventListener("click", onToolbarClick);
       toolbarRoot?.removeEventListener("change", back);
       memo.remove();
       picker.remove();
       brush.remove();
+      fmt.remove();
     },
   };
 
@@ -217,15 +207,8 @@ export function attachExtras(
       find: (replace) => find.open(replace),
       pasteSpecial: () => (armed = true),
       comment: editMemo,
-      filter: () => toggleFilter(ctx),
-      dropdown() {
-        const f = ctx.sheet().필터;
-        const g = f && parseRange(f.범위);
-        const { r, c } = ctx.selection.활성;
-        if (!g || r !== g.r0 || c < g.c0 || c > g.c1) return false;
-        filter.open(c);
-        return true;
-      },
+      formatDialog: openFormat,
+      ...data.keys,
       escape() {
         painter.clear();
         sticky = false;
@@ -248,6 +231,6 @@ export function attachExtras(
         put(comments.root!, hit.r, hit.c); // showBalloon 의 cellBox 자리 → 화면 자리로 고침
       },
     },
-    parts: [find, comments, filter, self],
+    parts: [find, comments, data.part, self],
   };
 }
diff --git a/A00_Common/spreadsheet/spreadsheet_functions.ts b/A00_Common/spreadsheet/spreadsheet_functions.ts
index a92ef894..4211ccf6 100644
--- a/A00_Common/spreadsheet/spreadsheet_functions.ts
+++ b/A00_Common/spreadsheet/spreadsheet_functions.ts
@@ -1,8 +1,9 @@
 /* =============================================================================
  * spreadsheet_functions.ts  (주인 B)
- * 함수 표 — 이름(대문자) → 뜻. 몸은 `spreadsheet_functions_math.ts` · `_misc.ts` · `_lookup.ts` 에
- * 두고 여기서 모음. 1단계 약 45 + 2단계 첫 묶음(2026-09-27) — 아래 `FUNC_HELP_BATCH2`(sub1 의
- * `spreadsheet_func_help.ts` 가 읽어 이름 목록에 더할 것 — 그 파일은 sub1 몫이라 안 고침).
+ * 함수 표 — 이름(대문자) → 뜻. 몸은 `spreadsheet_functions_math.ts` · `_misc.ts` · `_lookup.ts` ·
+ * `_stat.ts` 에 두고 여기서 모음. 1단계 약 45 + 2단계 묶음(2026-09-27) — 아래 `FUNC_HELP_BATCH2` ·
+ * `FUNC_HELP_BATCH3`(sub1 의 `spreadsheet_func_help.ts` 가 읽어 이름 목록에 둘 다 더할 것 —
+ * 그 파일은 sub1 몫이라 안 고침).
  * 없는 이름 = `#NAME?` · 인자 수가 min · max 밖이면 A 의 eval 이 `#VALUE!` + 까닭(엑셀은 입력을 막음).
  * ========================================================================== */
 
@@ -10,11 +11,13 @@ import type { SheetFunction } from "./spreadsheet_types";
 import { MATH_FUNCTIONS } from "./spreadsheet_functions_math";
 import { MISC_FUNCTIONS } from "./spreadsheet_functions_misc";
 import { LOOKUP_FUNCTIONS } from "./spreadsheet_functions_lookup";
+import { STAT_FUNCTIONS } from "./spreadsheet_functions_stat";
 
 const TABLE: Record<string, SheetFunction> = {
   ...MATH_FUNCTIONS,
   ...MISC_FUNCTIONS,
   ...LOOKUP_FUNCTIONS,
+  ...STAT_FUNCTIONS,
 };
 
 export function getFunction(name: string): SheetFunction | undefined {
@@ -119,3 +122,33 @@ export const FUNC_HELP_BATCH2: FuncHelpEntry[] = [
   { 이름: "MONTH", 꼴: "MONTH(일련번호)", 뜻: "월" },
   { 이름: "DAY", 꼴: "DAY(일련번호)", 뜻: "일" },
 ];
+
+/** 2단계 셋째 묶음(2026-09-27) — 위 `FUNC_HELP_BATCH2` 와 같은 모양 · 같이 sub1 표에 더할 것. */
+export const FUNC_HELP_BATCH3: FuncHelpEntry[] = [
+  { 이름: "MEDIAN", 꼴: "MEDIAN(수1, [수2], …)", 뜻: "가운데 값" },
+  { 이름: "MODE", 꼴: "MODE(수1, [수2], …)", 뜻: "가장 자주 나오는 값" },
+  { 이름: "STDEV", 꼴: "STDEV(수1, [수2], …)", 뜻: "표본 표준편차" },
+  { 이름: "STDEV.S", 꼴: "STDEV.S(수1, [수2], …)", 뜻: "표본 표준편차" },
+  { 이름: "STDEV.P", 꼴: "STDEV.P(수1, [수2], …)", 뜻: "모집단 표준편차" },
+  { 이름: "VAR", 꼴: "VAR(수1, [수2], …)", 뜻: "표본 분산" },
+  { 이름: "RANK", 꼴: "RANK(수, 범위, [순서=0])", 뜻: "범위 안 순위(0=내림차순)" },
+  { 이름: "RANK.EQ", 꼴: "RANK.EQ(수, 범위, [순서=0])", 뜻: "범위 안 순위(0=내림차순)" },
+  { 이름: "LARGE", 꼴: "LARGE(범위, k)", 뜻: "k 번째로 큰 값" },
+  { 이름: "SMALL", 꼴: "SMALL(범위, k)", 뜻: "k 번째로 작은 값" },
+  { 이름: "PERCENTILE", 꼴: "PERCENTILE(범위, k)", 뜻: "k(0~1) 자리 백분위 값" },
+  { 이름: "QUARTILE", 꼴: "QUARTILE(범위, 사분위수)", 뜻: "사분위수(0~4)" },
+  { 이름: "COUNTBLANK", 꼴: "COUNTBLANK(범위)", 뜻: "빈 칸 개수" },
+  { 이름: "NOW", 꼴: "NOW()", 뜻: "지금 날짜 · 시각(일련번호)" },
+  { 이름: "WEEKDAY", 꼴: "WEEKDAY(일련번호, [유형=1])", 뜻: "요일 번호" },
+  { 이름: "EDATE", 꼴: "EDATE(시작일, 개월수)", 뜻: "개월 뒤(앞) 같은 날" },
+  { 이름: "EOMONTH", 꼴: "EOMONTH(시작일, 개월수)", 뜻: "개월 뒤(앞) 달의 말일" },
+  { 이름: "DATEDIF", 꼴: "DATEDIF(시작일, 종료일, 단위)", 뜻: "두 날짜 차(단위 Y·M·D·YM·MD·YD)" },
+  {
+    이름: "NETWORKDAYS",
+    꼴: "NETWORKDAYS(시작일, 종료일, [휴일범위])",
+    뜻: "평일 일수(토·일 · 휴일 뺌)",
+  },
+  { 이름: "HOUR", 꼴: "HOUR(일련번호)", 뜻: "시" },
+  { 이름: "MINUTE", 꼴: "MINUTE(일련번호)", 뜻: "분" },
+  { 이름: "TIME", 꼴: "TIME(시, 분, 초)", 뜻: "시각 일련번호를 만듦" },
+];
diff --git a/A00_Common/spreadsheet/spreadsheet_functions_misc.ts b/A00_Common/spreadsheet/spreadsheet_functions_misc.ts
index dd33073f..5f3bcfc3 100644
--- a/A00_Common/spreadsheet/spreadsheet_functions_misc.ts
+++ b/A00_Common/spreadsheet/spreadsheet_functions_misc.ts
@@ -102,6 +102,58 @@ function dateToSerial(d: Date): number {
   return d.getTime() / MS_PER_DAY + UNIX_EPOCH_AS_EXCEL_SERIAL;
 }
 
+/** DATEDIF 낱자리(Y·M·D·YM·MD·YD) — 끝이 처음보다 이르면 `#NUM!` */
+function dateDiff(startSerial: number, endSerial: number, unit: string): number | ErrorValue {
+  const start = serialToDate(startSerial);
+  const end = serialToDate(endSerial);
+  if (end.getTime() < start.getTime()) return mkErr("#NUM!");
+  const u = unit.toUpperCase();
+  const sy = start.getUTCFullYear();
+  const sm = start.getUTCMonth();
+  const sd = start.getUTCDate();
+  const ey = end.getUTCFullYear();
+  const em = end.getUTCMonth();
+  const ed = end.getUTCDate();
+  if (u === "Y") {
+    let y = ey - sy;
+    if (em < sm || (em === sm && ed < sd)) y--;
+    return y;
+  }
+  if (u === "M") {
+    let m = (ey - sy) * 12 + (em - sm);
+    if (ed < sd) m--;
+    return m;
+  }
+  if (u === "D") return Math.round((end.getTime() - start.getTime()) / MS_PER_DAY);
+  if (u === "YM") {
+    let m = em - sm;
+    if (ed < sd) m--;
+    return ((m % 12) + 12) % 12;
+  }
+  if (u === "MD") {
+    let d = ed - sd;
+    if (d < 0) d += new Date(Date.UTC(ey, em, 0)).getUTCDate();
+    return d;
+  }
+  if (u === "YD") {
+    let days = Math.round((end.getTime() - Date.UTC(ey, sm, sd)) / MS_PER_DAY);
+    if (days < 0) days = Math.round((end.getTime() - Date.UTC(ey - 1, sm, sd)) / MS_PER_DAY);
+    return days;
+  }
+  return mkErr("#NUM!");
+}
+
+/** 일련번호의 소수부(하루 안 시각) → 시 · 분 · 초 */
+function timeParts(serial: number): { h: number; mnt: number; s: number } {
+  const dayFrac = serial - Math.floor(serial);
+  const totalSeconds = Math.round(dayFrac * 86400);
+  return {
+    h: Math.floor(totalSeconds / 3600) % 24,
+    mnt: Math.floor(totalSeconds / 60) % 60,
+    s: totalSeconds % 60,
+  };
+}
+
 // ── 함수 표 ──────────────────────────────────────────────────────────────
 
 export const MISC_FUNCTIONS: Record<string, SheetFunction> = {
@@ -466,4 +518,139 @@ export const MISC_FUNCTIONS: Record<string, SheetFunction> = {
       return isErr(n) ? n : frac(BigInt(serialToDate(fracToDouble(n)).getUTCDate()));
     },
   },
+  NOW: { min: 0, max: 0, call: () => fromDouble(dateToSerial(new Date())) },
+  WEEKDAY: {
+    min: 1,
+    max: 2,
+    call: (args) => {
+      const n = num(args[0]());
+      if (isErr(n)) return n;
+      const typeArg = args.length > 1 ? num(args[1]()) : ONE;
+      if (isErr(typeArg)) return typeArg;
+      const type = Math.trunc(fracToDouble(typeArg));
+      const dow = serialToDate(fracToDouble(n)).getUTCDay(); // 0=일 .. 6=토
+      if (type === 2) return frac(BigInt(((dow + 6) % 7) + 1));
+      if (type === 3) return frac(BigInt((dow + 6) % 7));
+      return frac(BigInt(dow + 1));
+    },
+  },
+  EDATE: {
+    min: 2,
+    max: 2,
+    call: (args) => {
+      const n = num(args[0]());
+      if (isErr(n)) return n;
+      const mArg = num(args[1]());
+      if (isErr(mArg)) return mArg;
+      const months = Math.trunc(fracToDouble(mArg));
+      const d = serialToDate(fracToDouble(n));
+      const targetMonth = d.getUTCMonth() + months;
+      // 달 끝을 넘는 날짜(1/31 + 1개월 등)는 다음 달로 넘기지 않고 그 달 말일로 눌러 담음(엑셀과 같음).
+      const lastDay = new Date(Date.UTC(d.getUTCFullYear(), targetMonth + 1, 0)).getUTCDate();
+      const day = Math.min(d.getUTCDate(), lastDay);
+      const date = new Date(Date.UTC(d.getUTCFullYear(), targetMonth, day));
+      return fromDouble(dateToSerial(date));
+    },
+  },
+  EOMONTH: {
+    min: 2,
+    max: 2,
+    call: (args) => {
+      const n = num(args[0]());
+      if (isErr(n)) return n;
+      const mArg = num(args[1]());
+      if (isErr(mArg)) return mArg;
+      const months = Math.trunc(fracToDouble(mArg));
+      const d = serialToDate(fracToDouble(n));
+      const date = new Date(Date.UTC(d.getUTCFullYear(), d.getUTCMonth() + months + 1, 0));
+      return fromDouble(dateToSerial(date));
+    },
+  },
+  DATEDIF: {
+    min: 3,
+    max: 3,
+    call: (args) => {
+      const s = num(args[0]());
+      if (isErr(s)) return s;
+      const e = num(args[1]());
+      if (isErr(e)) return e;
+      const unit = str(args[2]());
+      if (isErr(unit)) return unit;
+      const result = dateDiff(fracToDouble(s), fracToDouble(e), unit);
+      return isErr(result) ? result : frac(BigInt(result));
+    },
+  },
+  NETWORKDAYS: {
+    min: 2,
+    max: 3,
+    call: (args) => {
+      const s = num(args[0]());
+      if (isErr(s)) return s;
+      const e = num(args[1]());
+      if (isErr(e)) return e;
+      let startSerial = Math.round(fracToDouble(s));
+      let endSerial = Math.round(fracToDouble(e));
+      let sign = 1;
+      if (startSerial > endSerial) {
+        [startSerial, endSerial] = [endSerial, startSerial];
+        sign = -1;
+      }
+      const holidays = new Set<number>();
+      if (args.length > 2) {
+        const holidayArg = args[2]();
+        if (isRange(holidayArg)) {
+          for (let r = 0; r < holidayArg.rows; r++) {
+            for (let c = 0; c < holidayArg.cols; c++) {
+              const cell = holidayArg.at(r, c);
+              if (isFrac(cell)) holidays.add(Math.round(fracToDouble(cell)));
+            }
+          }
+        } else if (isFrac(holidayArg)) {
+          holidays.add(Math.round(fracToDouble(holidayArg)));
+        }
+      }
+      let count = 0;
+      for (let day = startSerial; day <= endSerial; day++) {
+        const dow = serialToDate(day).getUTCDay();
+        if (dow === 0 || dow === 6) continue;
+        if (holidays.has(day)) continue;
+        count++;
+      }
+      return frac(BigInt(sign * count));
+    },
+  },
+  HOUR: {
+    min: 1,
+    max: 1,
+    call: (args) => {
+      const n = num(args[0]());
+      return isErr(n) ? n : frac(BigInt(timeParts(fracToDouble(n)).h));
+    },
+  },
+  MINUTE: {
+    min: 1,
+    max: 1,
+    call: (args) => {
+      const n = num(args[0]());
+      return isErr(n) ? n : frac(BigInt(timeParts(fracToDouble(n)).mnt));
+    },
+  },
+  TIME: {
+    min: 3,
+    max: 3,
+    call: (args) => {
+      const hArg = num(args[0]());
+      if (isErr(hArg)) return hArg;
+      const mArg = num(args[1]());
+      if (isErr(mArg)) return mArg;
+      const sArg = num(args[2]());
+      if (isErr(sArg)) return sArg;
+      const totalSeconds =
+        Math.trunc(fracToDouble(hArg)) * 3600 +
+        Math.trunc(fracToDouble(mArg)) * 60 +
+        Math.trunc(fracToDouble(sArg));
+      const dayFraction = ((totalSeconds % 86400) + 86400) % 86400;
+      return fromDouble(dayFraction / 86400);
+    },
+  },
 };
diff --git a/A00_Common/spreadsheet/spreadsheet_functions_stat.ts b/A00_Common/spreadsheet/spreadsheet_functions_stat.ts
new file mode 100644
index 00000000..b64e73e5
--- /dev/null
+++ b/A00_Common/spreadsheet/spreadsheet_functions_stat.ts
@@ -0,0 +1,228 @@
+/* =============================================================================
+ * spreadsheet_functions_stat.ts  (주인 B · 3차 · 2026-09-27)
+ * 통계 함수 — MEDIAN · MODE · STDEV(.S/.P) · VAR · RANK(.EQ) · LARGE · SMALL ·
+ * PERCENTILE · QUARTILE · COUNTBLANK. 형 바꾸기 도우미는 `spreadsheet_functions_math.ts` 공용 것을 씀.
+ * ========================================================================== */
+
+import { ZERO, add, cmp, div, frac, mul, sub, type Frac } from "@ui/sheet/ui_template_sheet_frac";
+import type {
+  ErrorValue,
+  EvalContext,
+  EvalResult,
+  LazyArg,
+  RangeValue,
+  SheetFunction,
+} from "./spreadsheet_types";
+import {
+  collectNumbers,
+  fracToDouble,
+  fromDouble,
+  isErr,
+  isFrac,
+  isRange,
+  mkErr,
+  num,
+} from "./spreadsheet_functions_math";
+
+function rangeNumbers(range: RangeValue): Frac[] | ErrorValue {
+  const out: Frac[] = [];
+  for (let r = 0; r < range.rows; r++) {
+    for (let c = 0; c < range.cols; c++) {
+      const cell = range.at(r, c);
+      if (isErr(cell)) return cell;
+      if (isFrac(cell)) out.push(cell);
+    }
+  }
+  return out;
+}
+
+function meanAndSumSq(values: Frac[]): { mean: Frac; sumSq: Frac } {
+  const n = frac(BigInt(values.length));
+  const mean = div(values.reduce(add, ZERO), n);
+  const sumSq = values.reduce((acc, v) => add(acc, mul(sub(v, mean), sub(v, mean))), ZERO);
+  return { mean, sumSq };
+}
+
+function sampleVariance(values: Frac[]): Frac | ErrorValue {
+  if (values.length < 2) return mkErr("#DIV/0!");
+  return div(meanAndSumSq(values).sumSq, frac(BigInt(values.length - 1)));
+}
+
+function populationVariance(values: Frac[]): Frac | ErrorValue {
+  if (values.length < 1) return mkErr("#DIV/0!");
+  return div(meanAndSumSq(values).sumSq, frac(BigInt(values.length)));
+}
+
+function stdevOf(variance: Frac | ErrorValue): Frac | ErrorValue {
+  if (isErr(variance)) return variance;
+  return fromDouble(Math.sqrt(fracToDouble(variance)));
+}
+
+/** 정렬한 값에서 0 ≤ k ≤ 1 자리의 백분위(직선 보간 · 엑셀 PERCENTILE.INC 와 같음) */
+function percentileOf(values: Frac[], k: number): Frac | ErrorValue {
+  if (values.length === 0) return mkErr("#NUM!");
+  if (k < 0 || k > 1) return mkErr("#NUM!");
+  const sorted = [...values].sort((a, b) => cmp(a, b));
+  const pos = k * (sorted.length - 1);
+  const lowIdx = Math.floor(pos);
+  const highIdx = Math.ceil(pos);
+  if (lowIdx === highIdx) return sorted[lowIdx];
+  const weight = fromDouble(pos - lowIdx);
+  if (isErr(weight)) return weight;
+  return add(sorted[lowIdx], mul(weight, sub(sorted[highIdx], sorted[lowIdx])));
+}
+
+function nthOrderStat(range: RangeValue, k: number, largest: boolean): Frac | ErrorValue {
+  const values = rangeNumbers(range);
+  if (isErr(values)) return values;
+  if (k < 1 || k > values.length) return mkErr("#NUM!");
+  const sorted = [...values].sort((a, b) => cmp(a, b));
+  return sorted[largest ? sorted.length - k : k - 1];
+}
+
+function rankCall(args: LazyArg[], _ctx: EvalContext): EvalResult {
+  const target = num(args[0]());
+  if (isErr(target)) return target;
+  const range = args[1]();
+  if (!isRange(range)) return mkErr("#VALUE!");
+  const orderArg = args.length > 2 ? num(args[2]()) : ZERO;
+  if (isErr(orderArg)) return orderArg;
+  const ascending = cmp(orderArg, ZERO) !== 0;
+  let rank = 1;
+  let found = false;
+  for (let r = 0; r < range.rows; r++) {
+    for (let c = 0; c < range.cols; c++) {
+      const cell = range.at(r, c);
+      if (!isFrac(cell)) continue;
+      if (cmp(cell, target) === 0) found = true;
+      if (ascending ? cmp(cell, target) < 0 : cmp(cell, target) > 0) rank++;
+    }
+  }
+  return found ? frac(BigInt(rank)) : mkErr("#N/A");
+}
+
+export const STAT_FUNCTIONS: Record<string, SheetFunction> = {
+  MEDIAN: {
+    min: 1,
+    call: (args) => {
+      const values = collectNumbers(args, true, true);
+      if (isErr(values)) return values;
+      if (values.length === 0) return mkErr("#NUM!");
+      const sorted = [...values].sort((a, b) => cmp(a, b));
+      const mid = Math.floor(sorted.length / 2);
+      if (sorted.length % 2 === 1) return sorted[mid];
+      return div(add(sorted[mid - 1], sorted[mid]), frac(2n));
+    },
+  },
+  MODE: {
+    min: 1,
+    call: (args) => {
+      const values = collectNumbers(args, true, true);
+      if (isErr(values)) return values;
+      let bestIdx = -1;
+      let bestCount = 1;
+      for (let i = 0; i < values.length; i++) {
+        let count = 0;
+        for (const v of values) if (cmp(values[i], v) === 0) count++;
+        if (count > bestCount) {
+          bestCount = count;
+          bestIdx = i;
+        }
+      }
+      return bestIdx < 0 ? mkErr("#N/A") : values[bestIdx];
+    },
+  },
+  STDEV: {
+    min: 1,
+    call: (args) => {
+      const values = collectNumbers(args, true, true);
+      return isErr(values) ? values : stdevOf(sampleVariance(values));
+    },
+  },
+  "STDEV.S": {
+    min: 1,
+    call: (args) => {
+      const values = collectNumbers(args, true, true);
+      return isErr(values) ? values : stdevOf(sampleVariance(values));
+    },
+  },
+  "STDEV.P": {
+    min: 1,
+    call: (args) => {
+      const values = collectNumbers(args, true, true);
+      return isErr(values) ? values : stdevOf(populationVariance(values));
+    },
+  },
+  VAR: {
+    min: 1,
+    call: (args) => {
+      const values = collectNumbers(args, true, true);
+      return isErr(values) ? values : sampleVariance(values);
+    },
+  },
+  RANK: { min: 2, max: 3, call: rankCall },
+  "RANK.EQ": { min: 2, max: 3, call: rankCall },
+  LARGE: {
+    min: 2,
+    max: 2,
+    call: (args) => {
+      const range = args[0]();
+      if (!isRange(range)) return mkErr("#VALUE!");
+      const kArg = num(args[1]());
+      if (isErr(kArg)) return kArg;
+      return nthOrderStat(range, Math.trunc(fracToDouble(kArg)), true);
+    },
+  },
+  SMALL: {
+    min: 2,
+    max: 2,
+    call: (args) => {
+      const range = args[0]();
+      if (!isRange(range)) return mkErr("#VALUE!");
+      const kArg = num(args[1]());
+      if (isErr(kArg)) return kArg;
+      return nthOrderStat(range, Math.trunc(fracToDouble(kArg)), false);
+    },
+  },
+  PERCENTILE: {
+    min: 2,
+    max: 2,
+    call: (args) => {
+      const range = args[0]();
+      if (!isRange(range)) return mkErr("#VALUE!");
+      const kArg = num(args[1]());
+      if (isErr(kArg)) return kArg;
+      const values = rangeNumbers(range);
+      if (isErr(values)) return values;
+      return percentileOf(values, fracToDouble(kArg));
+    },
+  },
+  QUARTILE: {
+    min: 2,
+    max: 2,
+    call: (args) => {
+      const range = args[0]();
+      if (!isRange(range)) return mkErr("#VALUE!");
+      const qArg = num(args[1]());
+      if (isErr(qArg)) return qArg;
+      const q = Math.trunc(fracToDouble(qArg));
+      if (q < 0 || q > 4) return mkErr("#NUM!");
+      const values = rangeNumbers(range);
+      if (isErr(values)) return values;
+      return percentileOf(values, q / 4);
+    },
+  },
+  COUNTBLANK: {
+    min: 1,
+    max: 1,
+    call: (args) => {
+      const range = args[0]();
+      if (!isRange(range)) return mkErr("#VALUE!");
+      let count = 0;
+      for (let r = 0; r < range.rows; r++) {
+        for (let c = 0; c < range.cols; c++) if (range.at(r, c) === null) count++;
+      }
+      return frac(BigInt(count));
+    },
+  },
+};
diff --git a/A00_Common/spreadsheet/spreadsheet_graph.ts b/A00_Common/spreadsheet/spreadsheet_graph.ts
index 9487d333..7e9046da 100644
--- a/A00_Common/spreadsheet/spreadsheet_graph.ts
+++ b/A00_Common/spreadsheet/spreadsheet_graph.ts
@@ -82,6 +82,17 @@ function collectRefs(
   }
 }
 
+/** 나무 하나 풂 — 던진 오류는 오류 값으로(0 나눔 → `#DIV/0!` · 나머지 `#VALUE!`) */
+export function evalSafe(node: FormulaNode, ctx: EvalContext): EvalResult {
+  try {
+    return evaluate(node, ctx);
+  } catch (e) {
+    if (e instanceof FormulaError && e.message.startsWith("0 으로"))
+      return err("#DIV/0!", e.message);
+    return err("#VALUE!", e instanceof Error ? e.message : String(e));
+  }
+}
+
 /** 문서를 참조로 쥠 — 만들 때 전부 풂. */
 export function createCalcEngine(book: Workbook): CalcEngine {
   const parsed = new Map<string, ParseResult>();
@@ -285,15 +296,7 @@ export function createCalcEngine(book: Workbook): CalcEngine {
   function run(text: string, ctx: EvalContext): Scalar {
     const p = parse(text);
     if (!p.ok) return err("#NAME?", `식을 못 읽음: ${p.message} (${p.at + 1}번째 글자)`);
-    let v: EvalResult;
-    try {
-      v = evaluate(p.node, ctx);
-    } catch (e) {
-      if (e instanceof FormulaError && e.message.startsWith("0 으로"))
-        return err("#DIV/0!", e.message);
-      return err("#VALUE!", e instanceof Error ? e.message : String(e));
-    }
-    const one = intersect(v, ctx);
+    const one = intersect(evalSafe(p.node, ctx), ctx);
     return one === null ? ZERO : one;
   }
 
diff --git a/A00_Common/spreadsheet/spreadsheet_grid.ts b/A00_Common/spreadsheet/spreadsheet_grid.ts
index 4963d5b3..9aec9cba 100644
--- a/A00_Common/spreadsheet/spreadsheet_grid.ts
+++ b/A00_Common/spreadsheet/spreadsheet_grid.ts
@@ -576,6 +576,20 @@ export function createGrid(ctx: SpreadsheetContext): GridHandle {
     return { x, y, w: box.w, h: box.h };
   }
 
+  /** `overlay` 안 자리 — `overlay` 자신이 이미 머리 칸(headColW·headRowH)만큼 밀려 있어
+   * `screenBoxOf`(격자 뿌리 기준)를 그대로 쓰면 머리 칸만큼 두 번 밀림(찾은 버그 · 2026-09-27). */
+  function overlayBoxOf(r: number, c: number): CellBox {
+    const box = boxOf(r, c);
+    const inFrozenCol = c < frozenCols;
+    const inFrozenRow = r < frozenRows;
+    return {
+      x: inFrozenCol ? box.x : box.x - paneBR.scrollLeft,
+      y: inFrozenRow ? box.y : box.y - paneBR.scrollTop,
+      w: box.w,
+      h: box.h,
+    };
+  }
+
   function renderSelection(): void {
     let selLayer = overlay.querySelector<HTMLElement>(".aislo-grid__sel-layer");
     if (!selLayer) {
@@ -596,8 +610,8 @@ export function createGrid(ctx: SpreadsheetContext): GridHandle {
       const inFrozenCol = range.c0 < frozenCols;
       const inFrozenRow = range.r0 < frozenRows;
       const screen: CellBox = {
-        x: headColW() + (inFrozenCol ? box.x : box.x - paneBR.scrollLeft),
-        y: headRowH() + (inFrozenRow ? box.y : box.y - paneBR.scrollTop),
+        x: inFrozenCol ? box.x : box.x - paneBR.scrollLeft,
+        y: inFrozenRow ? box.y : box.y - paneBR.scrollTop,
         w: box.w,
         h: box.h,
       };
@@ -611,13 +625,11 @@ export function createGrid(ctx: SpreadsheetContext): GridHandle {
       node.style.borderWidth = i === 0 ? "2px" : "1px";
       selLayer!.append(node);
     }
-    const active = boxOf(sel.활성.r, sel.활성.c);
-    const inFrozenCol = sel.활성.c < frozenCols;
-    const inFrozenRow = sel.활성.r < frozenRows;
+    const active = overlayBoxOf(sel.활성.r, sel.활성.c);
     const handle = document.createElement("div");
     handle.className = "aislo-grid__fill-handle";
-    handle.style.left = `${headColW() + (inFrozenCol ? active.x : active.x - paneBR.scrollLeft) + active.w - 4}px`;
-    handle.style.top = `${headRowH() + (inFrozenRow ? active.y : active.y - paneBR.scrollTop) + active.h - 4}px`;
+    handle.style.left = `${active.x + active.w - 4}px`;
+    handle.style.top = `${active.y + active.h - 4}px`;
     selLayer!.append(handle);
   }
 
@@ -643,8 +655,8 @@ export function createGrid(ctx: SpreadsheetContext): GridHandle {
       const inFrozenRow = ref.범위.r0 < frozenRows;
       const node = document.createElement("div");
       node.className = "aislo-grid__ref-highlight";
-      node.style.left = `${headColW() + (inFrozenCol ? merged.x : merged.x - paneBR.scrollLeft)}px`;
-      node.style.top = `${headRowH() + (inFrozenRow ? merged.y : merged.y - paneBR.scrollTop)}px`;
+      node.style.left = `${inFrozenCol ? merged.x : merged.x - paneBR.scrollLeft}px`;
+      node.style.top = `${inFrozenRow ? merged.y : merged.y - paneBR.scrollTop}px`;
       node.style.width = `${merged.w}px`;
       node.style.height = `${merged.h}px`;
       node.style.borderColor = REF_COLORS[ref.색번호 % REF_COLORS.length];
diff --git a/A00_Common/spreadsheet/spreadsheet_keys.ts b/A00_Common/spreadsheet/spreadsheet_keys.ts
index a23180e1..b90a88b0 100644
--- a/A00_Common/spreadsheet/spreadsheet_keys.ts
+++ b/A00_Common/spreadsheet/spreadsheet_keys.ts
@@ -41,6 +41,8 @@ export interface KeyHooks {
   comment?(): void;
   /** 고름 중 Esc(서식 붓 끄기 등) */
   escape?(): void;
+  /** Ctrl+1 셀 서식 창 */
+  formatDialog?(): void;
   /** Ctrl+Shift+L 필터 켜기 · 끄기 */
   filter?(): void;
   /** Alt+↓ — 필터 머리 칸이면 값 목록을 열고 true */
@@ -68,12 +70,14 @@ export function attachKeys(ctx: SpreadsheetContext, ed: Editor, hooks: KeyHooks
         }
         if (ctrl) return (ed.commitAll(), true);
         ed.commit();
+        if (ed.editing()) return true; // 유효성에 막힘
         next(e.shiftKey ? -1 : 1, 0);
         return true;
       }
       case "Tab":
         if (!e.shiftKey && ed.accept()) return true; // 함수 자동 완성
         ed.commit();
+        if (ed.editing()) return true;
         next(0, e.shiftKey ? -1 : 1);
         return true;
       case "Escape":
@@ -92,7 +96,7 @@ export function attachKeys(ctx: SpreadsheetContext, ed: Editor, hooks: KeyHooks
     }
     if (e.shiftKey || ctrl) return false; // 글자 고르기 · 낱말 건너기는 textarea 에 맡김
     ed.commit();
-    go(move(ctx.sheet(), ctx.selection, arrow[0], arrow[1]));
+    if (!ed.editing()) go(move(ctx.sheet(), ctx.selection, arrow[0], arrow[1]));
     return true;
   }
 
@@ -140,6 +144,10 @@ export function attachKeys(ctx: SpreadsheetContext, ed: Editor, hooks: KeyHooks
           if (!hooks.find) return false;
           hooks.find(k === "h");
           return true;
+        case "1":
+          if (!hooks.formatDialog) return false;
+          hooks.formatDialog();
+          return true;
         case "l":
           if (!e.shiftKey || !hooks.filter) return false;
           hooks.filter();
diff --git a/A00_Common/spreadsheet/spreadsheet_mouse.ts b/A00_Common/spreadsheet/spreadsheet_mouse.ts
index 9100497f..4d5c03b8 100644
--- a/A00_Common/spreadsheet/spreadsheet_mouse.ts
+++ b/A00_Common/spreadsheet/spreadsheet_mouse.ts
@@ -106,7 +106,7 @@ export function attachMouse(
 
   function fillDrag(): void {
     const sheet = ctx.sheet();
-    const src = ctx.selection.범위[0];
+    const src = ctx.selection.범위[ctx.selection.범위.length - 1];
     let result = { target: src, clear: null as CellRange | null };
     drag(
       (p) => {
@@ -186,6 +186,7 @@ export function attachMouse(
         return;
       }
       ed.commit();
+      if (ed.editing()) return; // 유효성에 막힘
     }
     ed.focus();
     if (ctx.readOnly && hit.kind === "fillHandle") hit.kind = "cell";
@@ -205,9 +206,17 @@ export function attachMouse(
         return drag((p) => ctx.select(selectCols(sheet, a, p.c, a)));
       }
       case "cell": {
-        const first = e.shiftKey
+        // Ctrl = 범위 더함(여러 범위) · Shift = 마지막 범위를 늘림
+        const keep =
+          e.ctrlKey || e.metaKey
+            ? ctx.selection.범위
+            : e.shiftKey
+              ? ctx.selection.범위.slice(0, -1)
+              : [];
+        const one = e.shiftKey
           ? selectSpan(sheet, ctx.selection.기준, hit)
           : selectCell(sheet, hit.r, hit.c);
+        const first = { ...one, 범위: [...keep, ...one.범위] };
         ctx.select(first);
         const anchor = first.기준;
         let last = `${hit.r},${hit.c}`;
@@ -215,7 +224,8 @@ export function attachMouse(
           (p) => {
             if (`${p.r},${p.c}` === last) return;
             last = `${p.r},${p.c}`;
-            ctx.select(selectSpan(sheet, anchor, p));
+            const span = selectSpan(sheet, anchor, p);
+            ctx.select({ ...span, 범위: [...keep, ...span.범위] });
           },
           () => hooks.selected?.(),
         );
diff --git a/A00_Common/spreadsheet/spreadsheet_numfmt.ts b/A00_Common/spreadsheet/spreadsheet_numfmt.ts
index b6533dff..1c9fcb4f 100644
--- a/A00_Common/spreadsheet/spreadsheet_numfmt.ts
+++ b/A00_Common/spreadsheet/spreadsheet_numfmt.ts
@@ -3,7 +3,8 @@
  * 숫자 형식 코드 → 보이는 글 — 엑셀 코드 부분 집합: 일반 · `0` `#` `?` `.` `,`(천 단위 · 끝 쉼표 = 천으로 나눔) ·
  * 구역 `;`(양 · 음 · 0 · 글) · `"글"` · `\x` · `_x`(폭만큼 띄움) · `*x`(채움) · `[Red]` 등 색 · `%` · `@` · `E+00`.
  * 실무 형식(`0.00` · `_-* #,##0.00_-;\-* #,##0.00_-;_-* "-"_-;_-@_-` · `0.00_);[Red]\(0.00\)` …)은 모두 맞아야 함.
- * 끝수는 분수로 사사오입(엑셀 표시와 같음). 날짜 · 시간 형식은 1단계 밖(글 그대로).
+ * 끝수는 분수로 사사오입(엑셀 표시와 같음). 날짜 형식(`yyyy-mm-dd` · `m/d` · 요일 `aaa`/`aaaa`)도 봄
+ * (3차 · 2026-09-27) — 시간(`h:mm:ss`)은 아직 밖(글 그대로).
  * ========================================================================== */
 
 import {
@@ -364,6 +365,93 @@ function generalFormat(value: Frac): string {
   return fracToString(value);
 }
 
+// ── 날짜 형식(`yyyy-mm-dd` · `m/d` · 요일 `aaa`/`aaaa`) ───────────────────────
+// 엑셀 일련번호(1970-01-01 = 25569) → 달력. 1900 윤년 버그는 misc.ts 와 같이 안 다룸.
+
+const MS_PER_DAY = 86400000;
+const UNIX_EPOCH_AS_EXCEL_SERIAL = 25569;
+const WEEKDAY_SHORT = ["일", "월", "화", "수", "목", "금", "토"];
+
+function toDouble(x: Frac): number {
+  return Number(x.n) / Number(x.d);
+}
+
+function serialToDateUTC(serial: number): Date {
+  return new Date(Math.round((serial - UNIX_EPOCH_AS_EXCEL_SERIAL) * MS_PER_DAY));
+}
+
+type DatePart =
+  { k: "lit"; text: string } | { k: "y" | "m" | "d"; width: 1 | 2 | 4 } | { k: "a"; width: 3 | 4 };
+
+/** `y/m/d/a` 낱말 뜀(자리수가 아는 폭이 아니면 그대로 글로) — 없으면 날짜 형식 아님(null). */
+function detectDateFormat(s: string): DatePart[] | null {
+  const parts: DatePart[] = [];
+  let hasDateToken = false;
+  let i = 0;
+  while (i < s.length) {
+    const ch = s[i];
+    if (ch === '"') {
+      let j = i + 1;
+      let text = "";
+      while (j < s.length && s[j] !== '"') {
+        text += s[j];
+        j++;
+      }
+      parts.push({ k: "lit", text });
+      i = j + 1;
+      continue;
+    }
+    if (ch === "\\" && i + 1 < s.length) {
+      parts.push({ k: "lit", text: s[i + 1] });
+      i += 2;
+      continue;
+    }
+    const lower = ch.toLowerCase();
+    if (lower === "y" || lower === "m" || lower === "d" || lower === "a") {
+      let j = i;
+      while (j < s.length && s[j].toLowerCase() === lower) j++;
+      const width = j - i;
+      if (lower === "a" && (width === 3 || width === 4)) {
+        parts.push({ k: "a", width });
+        hasDateToken = true;
+      } else if (lower !== "a" && (width === 1 || width === 2 || (lower === "y" && width === 4))) {
+        parts.push({ k: lower as "y" | "m" | "d", width: width as 1 | 2 | 4 });
+        hasDateToken = true;
+      } else {
+        parts.push({ k: "lit", text: s.slice(i, j) });
+      }
+      i = j;
+      continue;
+    }
+    parts.push({ k: "lit", text: ch });
+    i++;
+  }
+  return hasDateToken ? parts : null;
+}
+
+function renderDatePart(part: DatePart, date: Date): string {
+  if (part.k === "lit") return part.text;
+  if (part.k === "y") {
+    const y = date.getUTCFullYear();
+    return part.width === 4 ? String(y) : String(y % 100).padStart(2, "0");
+  }
+  if (part.k === "m") {
+    const m = date.getUTCMonth() + 1;
+    return part.width === 1 ? String(m) : String(m).padStart(2, "0");
+  }
+  if (part.k === "d") {
+    const d = date.getUTCDate();
+    return part.width === 1 ? String(d) : String(d).padStart(2, "0");
+  }
+  const wd = WEEKDAY_SHORT[date.getUTCDay()];
+  return part.width === 3 ? wd : `${wd}요일`;
+}
+
+function renderDateSection(parts: DatePart[], value: Frac): string {
+  const date = serialToDateUTC(toDouble(value));
+  return parts.map((p) => renderDatePart(p, date)).join("");
+}
+
 function chooseSection(sections: string[], value: Frac): { code: string; forceMinus: boolean } {
   const isNeg = cmp(value, ZERO) < 0;
   const isZero = cmp(value, ZERO) === 0;
@@ -385,6 +473,12 @@ function formatNumber(value: Frac, code: string | undefined): FormattedText {
   const sections = splitSections(code);
   const { code: chosen, forceMinus } = chooseSection(sections, value);
   const { rest, color } = extractColor(chosen);
+  const datePlan = detectDateFormat(rest);
+  if (datePlan) {
+    const extra: Partial<FormattedText> = {};
+    if (color) extra.색 = color;
+    return { 글: renderDateSection(datePlan, value), 정렬: "right", ...extra };
+  }
   const { toks, fillChar } = tokenize(rest);
   const extra: Partial<FormattedText> = {};
   if (color) extra.색 = color;
diff --git a/A00_Common/spreadsheet/spreadsheet_parser.ts b/A00_Common/spreadsheet/spreadsheet_parser.ts
index 7279f7b0..4521067a 100644
--- a/A00_Common/spreadsheet/spreadsheet_parser.ts
+++ b/A00_Common/spreadsheet/spreadsheet_parser.ts
@@ -272,10 +272,19 @@ function prec(node: FormulaNode): number {
 
 const sheetHead = (sheet: string | null) => (sheet === null ? "" : `${quoteSheet(sheet)}!`);
 
-/** 나무 → 앞 `=` 뺀 식 글(참조 옮김 뒤 다시 적기) — 수는 원래 글(`text`) 그대로 · 괄호는 필요한 곳만 */
-export function formulaToText(node: FormulaNode): string {
+/** 나무 → 앞 `=` 뺀 식 글(참조 옮김 뒤 다시 적기) — 수는 원래 글(`text`) 그대로 · 괄호는 필요한 곳만.
+ * 계산 단계 보기용: `sub` 가 글을 주는 마디는 그 글(푼 값)로 갈음 · `mark` 마디는 \u0001 … \u0002 로 감쌈 */
+export function formulaToText(
+  node: FormulaNode,
+  sub?: (node: FormulaNode) => string | undefined,
+  mark?: FormulaNode,
+): string {
+  const own = sub?.(node);
+  if (own !== undefined) return own;
+  if (node === mark) return `\u0001${formulaToText(node, sub)}\u0002`;
+  const text = (child: FormulaNode) => formulaToText(child, sub, mark);
   const wrap = (child: FormulaNode, need: boolean) =>
-    need ? `(${formulaToText(child)})` : formulaToText(child);
+    need && sub?.(child) === undefined ? `(${text(child)})` : text(child);
   switch (node.type) {
     case "number":
       return node.text;
@@ -308,6 +317,6 @@ export function formulaToText(node: FormulaNode): string {
       return `${wrap(node.left, prec(node.left) < p)}${node.op}${wrap(node.right, prec(node.right) <= p)}`;
     }
     case "call":
-      return `${node.name}(${node.args.map(formulaToText).join(",")})`;
+      return `${node.name}(${node.args.map(text).join(",")})`;
   }
 }
diff --git a/A00_Common/spreadsheet/spreadsheet_selection.ts b/A00_Common/spreadsheet/spreadsheet_selection.ts
index 779324dc..310846e5 100644
--- a/A00_Common/spreadsheet/spreadsheet_selection.ts
+++ b/A00_Common/spreadsheet/spreadsheet_selection.ts
@@ -202,7 +202,7 @@ export function move(
     if (to.r === edge.r && to.c === edge.c) return selectCell(sheet, from.r, from.c);
     return selectCell(sheet, to.r, to.c);
   }
-  const g = sel.범위[0] ?? span(sel.활성, sel.활성);
+  const g = sel.범위[sel.범위.length - 1] ?? span(sel.활성, sel.활성); // 여러 범위면 마지막(활성) 범위
   const anchor = sel.기준;
   // 움직이는 끝 = 닻에서 먼 쪽
   const far = {
@@ -218,7 +218,7 @@ export function move(
   }
   return {
     시트: sheet.id,
-    범위: [expand(span(anchor, to), list)],
+    범위: [...sel.범위.slice(0, -1), expand(span(anchor, to), list)],
     활성: { ...sel.활성 },
     기준: { ...anchor },
   };
diff --git a/A00_Common/spreadsheet/spreadsheet_sheet_extra.ts b/A00_Common/spreadsheet/spreadsheet_sheet_extra.ts
new file mode 100644
index 00000000..a254ed7d
--- /dev/null
+++ b/A00_Common/spreadsheet/spreadsheet_sheet_extra.ts
@@ -0,0 +1,113 @@
+/* =============================================================================
+ * spreadsheet_sheet_extra.ts  (3단계 · 주인 sub_laptop_4)
+ * 시트 숨기기 · 보이기 · 시트 탭 색. 저장 자리 `Sheet.숨김` · `Sheet.탭색`(0 계약에 방금 더함).
+ * 이 파일은 관리 창(전체 시트 목록 + 숨김 · 색 조작)만 그림 — 실제 탭 줄(`spreadsheet_tabs.ts`,
+ * E 파일)을 안 건드림.
+ *
+ * 잇는 법(E `spreadsheet_tabs.ts` · sub7 — 지금은 하나도 안 이어짐):
+ *   1) `mountTabs` 의 `render()` 가 `ctx.book.시트` 를 돌 때 `숨김` 인 시트는 탭을 안 그림.
+ *   2) 탭 엘리먼트에 `sheet.탭색` 이 있으면 밑줄 · 배경을 그 색으로(엑셀처럼).
+ *   3) 숨은 시트를 다시 보이려면 탭 우클릭 메뉴에 [숨긴 시트 보이기] 항목을 두고 이 파일의
+ *      `createSheetExtraPanel(ctx)` 를 열거나, `showSheet(ctx, id)` 를 바로 부름.
+ * ========================================================================== */
+
+import { createButton, el } from "@ui/ui_template_elements";
+import type { Sheet } from "./spreadsheet_types";
+import type { PartHandle, SpreadsheetContext } from "./spreadsheet_view_types";
+
+// css 는 stage3.css 에 얹음(잇는 법 머리 참고) — 실제로 붙일 때 `import "./spreadsheet_stage3.css";` 더함.
+
+function applySheet(ctx: SpreadsheetContext, sheetId: string, next: Sheet): void {
+  ctx.dispatch({ 종류: "시트통째", 시트: { ...next, id: sheetId } });
+}
+
+/** 시트를 숨김 — 마지막 보이는 시트는 못 숨김(까닭 글 돌려줌 · 되면 null). 활성 시트를 숨기면
+ * 다른 보이는 시트로 활성을 옮김. */
+export function hideSheet(ctx: SpreadsheetContext, id: string): string | null {
+  const others = ctx.book.시트.filter((s) => s.id !== id && !s.숨김);
+  if (!others.length) return "마지막 보이는 시트는 못 숨김";
+  const sheet = ctx.book.시트.find((s) => s.id === id);
+  if (!sheet || sheet.숨김) return null;
+  applySheet(ctx, id, { ...sheet, 숨김: true });
+  if (ctx.book.활성 === id) ctx.showSheet(others[0].id);
+  return null;
+}
+
+/** 숨긴 시트를 다시 보임. */
+export function unhideSheet(ctx: SpreadsheetContext, id: string): void {
+  const sheet = ctx.book.시트.find((s) => s.id === id);
+  if (!sheet || !sheet.숨김) return;
+  applySheet(ctx, id, { ...sheet, 숨김: false });
+}
+
+/** 탭 색 — `color` 가 null 이면 색을 지움(기본 탭 색으로). */
+export function setSheetTabColor(ctx: SpreadsheetContext, id: string, color: string | null): void {
+  const sheet = ctx.book.시트.find((s) => s.id === id);
+  if (!sheet) return;
+  const next: Sheet = { ...sheet };
+  if (color) next.탭색 = color;
+  else delete next.탭색;
+  applySheet(ctx, id, next);
+}
+
+/** 시트 관리 창 — 전체 시트 목록 + 숨김 토글 · 탭 색 고르기. */
+export function createSheetExtraPanel(ctx: SpreadsheetContext): PartHandle {
+  const root = el("div", { className: "ss-sheetextra" });
+  const list = el("ul", { className: "ss-sheetextra__list" });
+  let error: HTMLElement | null = null;
+
+  const showError = (msg: string | null): void => {
+    error?.remove();
+    error = null;
+    if (!msg) return;
+    error = el("p", { text: msg });
+    error.style.color = "var(--color-danger, red)";
+    root.append(error);
+  };
+
+  function render(): void {
+    list.replaceChildren(
+      ...ctx.book.시트.map((sheet) => {
+        const li = el("li", { className: "ss-sheetextra__row" });
+        const label = el("span", { text: sheet.이름 + (sheet.숨김 ? "(숨김)" : "") });
+        const colorInput = el("input", {
+          attrs: { type: "color", value: sheet.탭색 ?? "#ffffff" },
+        }) as HTMLInputElement;
+        colorInput.addEventListener("change", () =>
+          setSheetTabColor(ctx, sheet.id, colorInput.value),
+        );
+        const colorClear = createButton({ label: "색 지움", variant: "ghost" });
+        colorClear.addEventListener("click", () => {
+          setSheetTabColor(ctx, sheet.id, null);
+          render();
+        });
+        const toggle = createButton({
+          label: sheet.숨김 ? "보이기" : "숨기기",
+          variant: "ghost",
+        });
+        toggle.addEventListener("click", () => {
+          if (sheet.숨김) {
+            unhideSheet(ctx, sheet.id);
+            showError(null);
+          } else {
+            showError(hideSheet(ctx, sheet.id));
+          }
+          render();
+        });
+        li.append(label, colorInput, colorClear, toggle);
+        return li;
+      }),
+    );
+  }
+
+  root.append(el("h4", { text: "시트 관리" }), list);
+  render();
+
+  return {
+    root,
+    refresh: render,
+    destroy(): void {
+      root.remove();
+    },
+  };
+}
diff --git a/A00_Common/spreadsheet/spreadsheet_stage3.css b/A00_Common/spreadsheet/spreadsheet_stage3.css
index 9f7d71cd..68cf46de 100644
--- a/A00_Common/spreadsheet/spreadsheet_stage3.css
+++ b/A00_Common/spreadsheet/spreadsheet_stage3.css
@@ -1,11 +1,13 @@
 /* =============================================================================
  * spreadsheet_stage3.css  (주인 sub_laptop_4)
- * 조건부 서식 · 데이터 유효성 · 이름 정의 관리 창 — 화면 스타일 한 벌. 색 · 간격은 테마 토큰만.
+ * 조건부 서식 · 데이터 유효성 · 이름 정의 · 상태 표시줄 · 시트 관리 창 — 화면 스타일 한 벌.
+ * 색 · 간격은 테마 토큰만.
  * ========================================================================== */
 
 .ss-condfmt,
 .ss-validation,
-.ss-names {
+.ss-names,
+.ss-sheetextra {
   display: flex;
   flex-direction: column;
   gap: var(--spacing-8);
@@ -18,7 +20,8 @@
 
 .ss-condfmt__list,
 .ss-validation__list,
-.ss-names__list {
+.ss-names__list,
+.ss-sheetextra__list {
   list-style: none;
   margin: 0;
   padding: 0;
@@ -29,7 +32,8 @@
 
 .ss-condfmt__row,
 .ss-validation__row,
-.ss-names__row {
+.ss-names__row,
+.ss-sheetextra__row {
   display: flex;
   align-items: center;
   gap: var(--spacing-4);
@@ -85,3 +89,23 @@
 .ss-validation__dropdown-item:hover {
   background: var(--color-mist-violet);
 }
+
+.ss-statusbar {
+  display: flex;
+  align-items: center;
+  gap: var(--spacing-8);
+  padding: 2px var(--spacing-8);
+  background: var(--color-surface);
+  border-top: 1px solid var(--color-border);
+  font-size: 0.8rem;
+}
+
+.ss-statusbar__stats {
+  display: flex;
+  gap: var(--spacing-8);
+  flex: 1;
+}
+
+.ss-statusbar__zoom {
+  color: var(--color-border);
+}
diff --git a/A00_Common/spreadsheet/spreadsheet_statusbar.ts b/A00_Common/spreadsheet/spreadsheet_statusbar.ts
new file mode 100644
index 00000000..fb7ce797
--- /dev/null
+++ b/A00_Common/spreadsheet/spreadsheet_statusbar.ts
@@ -0,0 +1,122 @@
+/* =============================================================================
+ * spreadsheet_statusbar.ts  (3단계 · 주인 sub_laptop_4)
+ * 아래 상태 표시줄 — 고른 범위의 합계 · 평균 · 개수(COUNTA) · 숫자 개수(COUNT) · 최소 · 최대.
+ * 엑셀처럼 우클릭으로 보일 줄 고름(이 표시줄만의 취향 — 문서에는 안 남음 · 계약 손 안 댐).
+ * 확대 비율 자리는 칸만 둠 — 실제 격자 확대와는 아직 안 이어짐(아래 「잇는 법」 2).
+ *
+ * 잇는 법(D · C · sub7 — 지금은 하나도 안 이어짐):
+ *   1) `spreadsheet.ts` 가 `createStatusBar(ctx)` 를 한 번 부르고 `root` 를 화면 맨 아래 붙임.
+ *      `ctx.select()` 뒤(그리고 `dispatch` 로 값이 바뀐 뒤) `refresh()` 를 부름 — 스스로 구독 안 함.
+ *   2) 확대 비율을 실제로 쓰려면 `GridHandle` 에 `zoom()` · `setZoom()` 을 계약(0)에 더하고(격자 C 몫),
+ *      이 파일의 확대 자리를 그 값으로 채우고 바꾸면 `setZoom` 을 부르게 이음.
+ * ========================================================================== */
+
+import { el } from "@ui/ui_template_elements";
+import { createMapContextMenu, type MapContextMenuItem } from "@ui/ui_template_context_menu";
+import { isFrac, fracToDouble } from "./spreadsheet_functions_math";
+import type { CellRange, Scalar } from "./spreadsheet_types";
+import type { PartHandle, SpreadsheetContext } from "./spreadsheet_view_types";
+
+// css 는 stage3.css 에 얹음(잇는 법 머리 참고) — 실제로 붙일 때 `import "./spreadsheet_stage3.css";` 더함.
+
+export type StatKey = "합계" | "평균" | "개수" | "숫자개수" | "최소" | "최대";
+
+export const STAT_KEYS: StatKey[] = ["합계", "평균", "개수", "숫자개수", "최소", "최대"];
+
+export interface SelectionStats {
+  합계: number | null;
+  평균: number | null;
+  개수: number;
+  숫자개수: number;
+  최소: number | null;
+  최대: number | null;
+}
+
+/** 고른 범위(여럿) 안 칸 값을 모아 통계를 냄 — 엔진 값 기준(식 칸도 풀린 값). */
+export function computeSelectionStats(ctx: SpreadsheetContext): SelectionStats {
+  const sheet = ctx.selection.시트;
+  const nums: number[] = [];
+  let 개수 = 0;
+  const seen = new Set<number>();
+
+  const visit = (range: CellRange): void => {
+    for (let r = range.r0; r <= range.r1; r++) {
+      for (let c = range.c0; c <= range.c1; c++) {
+        const key = r * 1_000_000 + c;
+        if (seen.has(key)) continue;
+        seen.add(key);
+        const value: Scalar = ctx.engine.value(sheet, r, c);
+        if (value === null) continue;
+        개수++;
+        if (isFrac(value)) nums.push(fracToDouble(value));
+      }
+    }
+  };
+  for (const range of ctx.selection.범위) visit(range);
+
+  return {
+    합계: nums.length ? nums.reduce((a, b) => a + b, 0) : null,
+    평균: nums.length ? nums.reduce((a, b) => a + b, 0) / nums.length : null,
+    개수,
+    숫자개수: nums.length,
+    최소: nums.length ? Math.min(...nums) : null,
+    최대: nums.length ? Math.max(...nums) : null,
+  };
+}
+
+function statText(key: StatKey, stats: SelectionStats): string {
+  const value = stats[key];
+  if (key === "개수" || key === "숫자개수") return `${key}: ${value}`;
+  return `${key}: ${value === null ? "—" : formatNumber(value)}`;
+}
+
+function formatNumber(n: number): string {
+  return Number.isInteger(n)
+    ? String(n)
+    : n.toLocaleString(undefined, { maximumFractionDigits: 4 });
+}
+
+/** 아래 상태 표시줄 — 우클릭 메뉴로 보일 줄 고름. */
+export function createStatusBar(ctx: SpreadsheetContext): PartHandle {
+  const root = el("div", { className: "ss-statusbar" });
+  const stats = el("div", { className: "ss-statusbar__stats" });
+  const zoom = el("span", { className: "ss-statusbar__zoom", text: "확대 100%" });
+  const menu = createMapContextMenu("ss-statusbar");
+  root.append(stats, zoom, menu.element);
+
+  let visible = new Set<StatKey>(STAT_KEYS);
+
+  function render(): void {
+    const s = computeSelectionStats(ctx);
+    stats.replaceChildren(
+      ...STAT_KEYS.filter((k) => visible.has(k)).map((k) =>
+        el("span", { className: "ss-statusbar__item", text: statText(k, s) }),
+      ),
+    );
+  }
+
+  root.addEventListener("contextmenu", (ev) => {
+    ev.preventDefault();
+    const box = root.getBoundingClientRect();
+    const items: MapContextMenuItem[] = STAT_KEYS.map((k) => [
+      `${visible.has(k) ? "✓ " : ""}${k}`,
+      () => {
+        if (visible.has(k)) visible.delete(k);
+        else visible.add(k);
+        render();
+      },
+    ]);
+    menu.open(ev.clientX - box.left, ev.clientY - box.top, items);
+  });
+
+  render();
+
+  return {
+    root,
+    refresh: render,
+    destroy(): void {
+      menu.close();
+      root.remove();
+    },
+  };
+}
diff --git a/A00_Common/spreadsheet/spreadsheet_trace.ts b/A00_Common/spreadsheet/spreadsheet_trace.ts
new file mode 100644
index 00000000..d676a0ec
--- /dev/null
+++ b/A00_Common/spreadsheet/spreadsheet_trace.ts
@@ -0,0 +1,285 @@
+/* =============================================================================
+ * spreadsheet_trace.ts  (주인 A)
+ * 선행 · 종속 칸 추적 화살표(엑셀 [수식 분석]) — 엔진 의존 그래프(`engine.precedents`)로 한 단계씩 넓힘.
+ * 엑셀 규칙: 누를 때마다 한 단계 더(이미 편 칸 너머만) · 범위는 파란 상자 + 화살 · 오류 칸에서 나온 화살은 빨강 ·
+ * 다른 시트 칸은 점선 화살 + 시트 표 아이콘 · 문서가 바뀌면 화살을 모두 지움.
+ *
+ * 잇는 법(D · sub7):
+ *   · 부품 붙이기: `const trace = attachTrace(ctx)` — SVG 겹판을 격자 overlay(editorSlot 층)에 얹음.
+ *     grid.render() 뒤마다 `trace.refresh()` · 스크롤은 스스로 따라감 · 시트를 바꾸면 그 시트 화살만 그림.
+ *   · 도구 모음 [수식 분석]: 「선행 참조 추적」 → `trace.precedents()` · 「종속 참조 추적」 → `trace.dependents()` ·
+ *     「화살표 지우기」 → `trace.clear()`(종류만 지우려면 `clear("선행")`). 더 펼 칸이 없으면 false(토스트 몫).
+ * ========================================================================== */
+
+import { cellId, inRange, parseA1 } from "./spreadsheet_address";
+import { isError } from "./spreadsheet_eval";
+import type { CalcEngine, CellRange, SheetCellAddress, Workbook } from "./spreadsheet_types";
+import type { PartHandle, SpreadsheetContext } from "./spreadsheet_view_types";
+
+export type TraceKind = "선행" | "종속";
+
+/** 화살 하나 — 늘 가리켜진 쪽(from) → 식 칸(to) */
+export interface TraceArrow {
+  종류: TraceKind;
+  from: { 시트: string; 범위: CellRange };
+  to: SheetCellAddress;
+  /** 시작 칸 · 범위에 오류 값이 있음 → 빨강 */
+  오류: boolean;
+}
+
+export interface TraceState {
+  arrows: TraceArrow[];
+  /** 이미 편 칸(`종류:시트!id`) */
+  opened: Set<string>;
+}
+
+const key = (kind: TraceKind, sheet: string, r: number, c: number) =>
+  `${kind}:${sheet}!${cellId(r, c)}`;
+const one = (r: number, c: number): CellRange => ({ r0: r, c0: c, r1: r, c1: c });
+
+/** 시트의 식 칸 목록(범위 안만) */
+function formulaCells(book: Workbook, sheet: string, rg?: CellRange): SheetCellAddress[] {
+  const s = book.시트.find((x) => x.id === sheet);
+  const out: SheetCellAddress[] = [];
+  for (const [a1, cell] of Object.entries(s?.칸 ?? {})) {
+    const at = cell.식 !== undefined ? parseA1(a1) : null;
+    if (at && (!rg || inRange(rg, at.r, at.c))) out.push({ 시트: sheet, ...at });
+  }
+  return out;
+}
+
+function hasError(book: Workbook, engine: CalcEngine, sheet: string, rg: CellRange): boolean {
+  if (rg.r0 === rg.r1 && rg.c0 === rg.c1) return isError(engine.value(sheet, rg.r0, rg.c0));
+  const s = book.시트.find((x) => x.id === sheet);
+  for (const a1 of Object.keys(s?.칸 ?? {})) {
+    const at = parseA1(a1);
+    if (at && inRange(rg, at.r, at.c) && isError(engine.value(sheet, at.r, at.c))) return true;
+  }
+  return false;
+}
+
+/** 칸을 가리키는 식 칸들(모든 시트) */
+export function dependentsOf(
+  book: Workbook,
+  engine: CalcEngine,
+  sheet: string,
+  r: number,
+  c: number,
+): SheetCellAddress[] {
+  const out: SheetCellAddress[] = [];
+  for (const s of book.시트)
+    for (const f of formulaCells(book, s.id))
+      if (
+        engine.precedents(f.시트, f.r, f.c).some((d) => d.시트 === sheet && inRange(d.범위, r, c))
+      )
+        out.push(f);
+  return out;
+}
+
+/** 한 단계 넓힘 — 처음이면 그 칸 · 아니면 그 칸에서 이어진 화살 끝 중 아직 안 편 칸. 더한 화살이 있으면 true */
+export function traceStep(
+  book: Workbook,
+  engine: CalcEngine,
+  state: TraceState,
+  kind: TraceKind,
+  at: SheetCellAddress,
+): boolean {
+  // 이어진 칸을 따라가며 안 편 칸(앞날개)을 모음
+  const frontier: SheetCellAddress[] = [];
+  const seen = new Set<string>();
+  const walk = [at];
+  while (walk.length) {
+    const p = walk.pop()!;
+    const k = key(kind, p.시트, p.r, p.c);
+    if (seen.has(k)) continue;
+    seen.add(k);
+    if (!state.opened.has(k)) {
+      frontier.push(p);
+      continue;
+    }
+    for (const a of state.arrows) {
+      if (a.종류 !== kind) continue;
+      if (kind === "선행" && a.to.시트 === p.시트 && a.to.r === p.r && a.to.c === p.c)
+        walk.push(...formulaCells(book, a.from.시트, a.from.범위));
+      if (kind === "종속" && a.from.시트 === p.시트 && inRange(a.from.범위, p.r, p.c))
+        walk.push(a.to);
+    }
+  }
+  let added = false;
+  for (const p of frontier) {
+    state.opened.add(key(kind, p.시트, p.r, p.c));
+    const links =
+      kind === "선행"
+        ? engine.precedents(p.시트, p.r, p.c).map((d) => ({ from: d, to: p }))
+        : dependentsOf(book, engine, p.시트, p.r, p.c).map((to) => ({
+            from: { 시트: p.시트, 범위: one(p.r, p.c) },
+            to,
+          }));
+    for (const { from, to } of links) {
+      state.arrows.push({
+        종류: kind,
+        from,
+        to,
+        오류: hasError(book, engine, from.시트, from.범위),
+      });
+      added = true;
+    }
+  }
+  return added;
+}
+
+// ── 화면 겹판 ────────────────────────────────────────────────────────────────
+
+const SVG = "http://www.w3.org/2000/svg";
+const svg = <K extends keyof SVGElementTagNameMap>(
+  tag: K,
+  attrs: Record<string, string | number>,
+) => {
+  const n = document.createElementNS(SVG, tag);
+  for (const [a, v] of Object.entries(attrs)) n.setAttribute(a, String(v));
+  return n;
+};
+
+export interface TraceHandle extends PartHandle {
+  /** 활성 칸 선행 추적 한 단계 — 더한 화살이 없으면 false */
+  precedents(): boolean;
+  dependents(): boolean;
+  clear(kind?: TraceKind): void;
+  /** 지금 화살(시험 · 상태 표시용) */
+  arrows(): readonly TraceArrow[];
+}
+
+export function attachTrace(ctx: SpreadsheetContext): TraceHandle {
+  const layer = svg("svg", { class: "ss-trace" });
+  const defs = svg("defs", {});
+  for (const kind of ["plain", "error", "sheet"]) {
+    const m = svg("marker", {
+      id: `ss-trace-head-${kind}`,
+      viewBox: "0 0 10 10",
+      refX: 9,
+      refY: 5,
+      markerWidth: 7,
+      markerHeight: 7,
+      orient: "auto-start-reverse",
+    });
+    m.append(svg("path", { d: "M0,0 L10,5 L0,10 z", class: `ss-trace__head is-${kind}` }));
+    defs.append(m);
+  }
+  let state: TraceState = { arrows: [], opened: new Set() };
+  let book = ctx.book;
+
+  /** 칸 상자 → 겹판 자리(filter 와 같은 맞춤) */
+  function boxIn(r: number, c: number) {
+    const { layer: host, box } = ctx.grid.editorSlot(r, c);
+    const a = host.getBoundingClientRect();
+    const g = ctx.grid.root.getBoundingClientRect();
+    return { ...box, x: box.x - (a.left - g.left), y: box.y - (a.top - g.top) };
+  }
+
+  function draw(): void {
+    if (ctx.book !== book) {
+      state = { arrows: [], opened: new Set() };
+      book = ctx.book;
+    }
+    const { layer: host } = ctx.grid.editorSlot(0, 0);
+    if (layer.parentElement !== host) host.append(layer);
+    const here = ctx.sheet().id;
+    const parts: SVGElement[] = [defs];
+    const boxes = new Set<string>();
+    for (const a of state.arrows) {
+      const fromHere = a.from.시트 === here;
+      const toHere = a.to.시트 === here;
+      if (!fromHere && !toHere) continue;
+      const tone = a.오류 ? "error" : fromHere && toHere ? "plain" : "sheet";
+      const t = toHere ? boxIn(a.to.r, a.to.c) : null;
+      const rg = a.from.범위;
+      const f = fromHere ? boxIn(rg.r0, rg.c0) : null;
+      const end = t
+        ? { x: t.x + t.w / 2, y: t.y + t.h / 2 }
+        : { x: f!.x + f!.w + 60, y: f!.y - 24 };
+      const start = f
+        ? { x: f.x + Math.min(f.w, 24) / 2, y: f.y + f.h / 2 }
+        : { x: t!.x - 60, y: t!.y - 24 };
+      if (
+        f &&
+        (rg.r0 !== rg.r1 || rg.c0 !== rg.c1) &&
+        !boxes.has(`${rg.r0},${rg.c0},${rg.r1},${rg.c1}`)
+      ) {
+        boxes.add(`${rg.r0},${rg.c0},${rg.r1},${rg.c1}`);
+        const b = boxIn(rg.r1, rg.c1);
+        parts.push(
+          svg("rect", {
+            class: `ss-trace__box is-${a.오류 ? "error" : "plain"}`,
+            x: f.x + 1,
+            y: f.y + 1,
+            width: Math.max(0, b.x + b.w - f.x - 2),
+            height: Math.max(0, b.y + b.h - f.y - 2),
+          }),
+        );
+      }
+      if (f)
+        parts.push(
+          svg("circle", { class: `ss-trace__dot is-${tone}`, cx: start.x, cy: start.y, r: 3 }),
+        );
+      else
+        parts.push(
+          svg("rect", {
+            class: "ss-trace__sheet",
+            x: start.x - 9,
+            y: start.y - 7,
+            width: 18,
+            height: 14,
+          }),
+        );
+      parts.push(
+        svg("line", {
+          class: `ss-trace__line is-${tone}`,
+          x1: start.x,
+          y1: start.y,
+          x2: end.x,
+          y2: end.y,
+          "marker-end": `url(#ss-trace-head-${tone})`,
+          "data-from": `${a.from.시트}!${rg.r0},${rg.c0}`,
+          "data-to": `${a.to.시트}!${a.to.r},${a.to.c}`,
+        }),
+      );
+      if (!t)
+        parts.push(
+          svg("rect", { class: "ss-trace__sheet", x: end.x, y: end.y - 7, width: 18, height: 14 }),
+        );
+    }
+    layer.replaceChildren(...parts);
+  }
+
+  const step = (kind: TraceKind) => {
+    if (ctx.book !== book) draw();
+    const { r, c } = ctx.selection.활성;
+    const added = traceStep(ctx.book, ctx.engine, state, kind, { 시트: ctx.sheet().id, r, c });
+    draw();
+    return added;
+  };
+
+  const onScroll = () => draw();
+  ctx.grid.root.addEventListener("scroll", onScroll, true);
+  draw();
+
+  return {
+    root: layer as unknown as HTMLElement,
+    refresh: draw,
+    precedents: () => step("선행"),
+    dependents: () => step("종속"),
+    clear(kind) {
+      if (!kind) state = { arrows: [], opened: new Set() };
+      else {
+        state.arrows = state.arrows.filter((a) => a.종류 !== kind);
+        for (const k of [...state.opened]) if (k.startsWith(`${kind}:`)) state.opened.delete(k);
+      }
+      draw();
+    },
+    arrows: () => state.arrows,
+    destroy() {
+      ctx.grid.root.removeEventListener("scroll", onScroll, true);
+      layer.remove();
+    },
+  };
+}
diff --git a/A00_Common/spreadsheet/spreadsheet_types.ts b/A00_Common/spreadsheet/spreadsheet_types.ts
index 94d6f73c..b86ae188 100644
--- a/A00_Common/spreadsheet/spreadsheet_types.ts
+++ b/A00_Common/spreadsheet/spreadsheet_types.ts
@@ -31,6 +31,10 @@
  *   A  spreadsheet_sort_dialog.ts     정렬 대화 상자 · 빠른 정렬(화면)                   ~250
  *   A  spreadsheet_filter.ts          자동 필터 단추 · 값 목록 창(화면)                  ~300
  *   A  spreadsheet_sortfilter.css                                                     ~150
+ *   A  spreadsheet_trace.ts           선행 · 종속 추적 화살표(한 단계씩 · SVG 겹판)        ~270
+ *   A  spreadsheet_eval_steps.ts      수식 계산 단계 보기 창                               ~230
+ *   A  spreadsheet_errcheck.ts        오류 검사 까닭 · ⚠ 단추 · 풍선(세모는 C 가 그림)     ~200
+ *   A  spreadsheet_analysis.css       위 셋 화면 스타일                                    ~200
  *   A  spreadsheet_recalc.ts          통합문서 한 벌 풀이(서버 Node · 시험 진입)        ~80
  *   B  spreadsheet_functions.ts       함수 표(이름 → 뜻) · 인자 수 검사                 ~120
  *   B  spreadsheet_functions_math.ts  수학 · 삼각 · 끝수                               ~400
@@ -55,7 +59,10 @@
  *   3  spreadsheet_condfmt.ts        조건부 서식 규칙 · 관리 창(주인 sub_laptop_4 · 안 이어짐) ~260
  *   3  spreadsheet_validation.ts     데이터 유효성 규칙 · 관리 창(주인 sub_laptop_4 · 안 이어짐) ~230
  *   3  spreadsheet_names.ts          이름 정의 · 이름 관리 창(주인 sub_laptop_4 · 안 이어짐)     ~220
- *   3  spreadsheet_stage3.css        위 셋 화면 스타일 한 벌                                      ~90
+ *   3  spreadsheet_statusbar.ts      아래 상태 표시줄 — 합계 · 평균 · 개수 등(주인 sub_laptop_4 · 안 이어짐) ~150
+ *   3  spreadsheet_autosum.ts        자동 합계(Alt+= · Σ, 주인 sub_laptop_4 · 안 이어짐)          ~90
+ *   3  spreadsheet_sheet_extra.ts    시트 숨김 · 보이기 · 탭 색(주인 sub_laptop_4 · 계약 더함 · 안 이어짐) ~150
+ *   3  spreadsheet_stage3.css        위 여섯 화면 스타일 한 벌                                    ~140
  *   F  common_util/common_util_spreadsheet_node.ts   Node 진입(재계산 · 폴더 밖)       ~40
  *   F  common_util/common_util_spreadsheet.py        파이썬 껍데기(common_util_node_bundle) ~60
  *   F  package.json `build:spreadsheet` · M02 `basis` 종류(Store · Layers) · 옛 산출근거 옮김 ·
@@ -172,6 +179,10 @@ export interface Sheet {
   /** 이 시트에서 정의한 이름 — 범위는 이 시트 안(`spreadsheet_names.ts`). 식 나무의 `{type:"name"}` 는
    * A 의 eval 이 `resolveName` 으로 풀어야 함(지금 안 이어짐 — 8-3 절 참고). */
   이름정의?: NamedRange[];
+  /** 시트 숨김(`spreadsheet_sheet_extra.ts`) — 탭은 `spreadsheet_tabs.ts`(E)가 이 값으로 걸러야 함(안 이어짐). */
+  숨김?: boolean;
+  /** 시트 탭 색 `#RRGGBB`(`spreadsheet_sheet_extra.ts`) — 탭 칠은 E 몫(안 이어짐). */
+  탭색?: string;
 }
 
 /** 새 시트 기본값 — 값은 사용자 협의로 확정(9_엑셀검토 8장 · 임의 확정 금지). 없으면 A 의 임시값. */
diff --git a/resources/tester/spreadsheet/harness_analysis.html b/resources/tester/spreadsheet/harness_analysis.html
new file mode 100644
index 00000000..a0eb863d
--- /dev/null
+++ b/resources/tester/spreadsheet/harness_analysis.html
@@ -0,0 +1,27 @@
+<!doctype html>
+<html lang="ko">
+  <head>
+    <meta charset="utf-8" />
+    <title>수식 분석 시험 틀</title>
+    <link rel="stylesheet" href="../../../ui_template/ui_template_theme.css" />
+    <style>
+      body { margin: 0; font-family: sans-serif; }
+      #bar { margin: 8px; display: flex; gap: 8px; }
+      #host { height: 520px; margin: 8px; border: 1px solid #999; }
+    </style>
+  </head>
+  <body>
+    <div id="bar">
+      <button id="btn-prec">선행 참조 추적</button>
+      <button id="btn-dep">종속 참조 추적</button>
+      <button id="btn-clear">화살표 지우기</button>
+      <button id="btn-steps">수식 계산</button>
+    </div>
+    <div id="host"></div>
+    <script>
+      window.ssErrors = [];
+      window.addEventListener("error", (e) => window.ssErrors.push(String(e.error?.stack || e.message)));
+    </script>
+    <script src="../../../tmp/spreadsheet_analysis/harness.js"></script>
+  </body>
+</html>
diff --git a/resources/tester/spreadsheet/harness_analysis.ts b/resources/tester/spreadsheet/harness_analysis.ts
new file mode 100644
index 00000000..7e754fbb
--- /dev/null
+++ b/resources/tester/spreadsheet/harness_analysis.ts
@@ -0,0 +1,72 @@
+/* 수식 분석 화면 시험 틀 — 진짜 부품(createSpreadsheet)에 추적 화살 · 수식 계산 창 · 오류 ⚠ 를 붙임.
+ * sub7 잇기 전이라 `inspect` 로 문맥(ctx)을 꺼내고, grid.render 뒤 refresh 를 부름.
+ * 번들: node harness_analysis_bundle.cjs → tmp/spreadsheet_analysis/harness.js (git 밖) */
+import { createSpreadsheet } from "../../../A00_Common/spreadsheet/spreadsheet";
+import { attachTrace } from "../../../A00_Common/spreadsheet/spreadsheet_trace";
+import { openEvalSteps } from "../../../A00_Common/spreadsheet/spreadsheet_eval_steps";
+import { attachErrorTip } from "../../../A00_Common/spreadsheet/spreadsheet_errcheck";
+import type { SpreadsheetContext } from "../../../A00_Common/spreadsheet/spreadsheet_view_types";
+import type { Workbook } from "../../../A00_Common/spreadsheet/spreadsheet_types";
+
+const w = window as unknown as Record<string, unknown>;
+
+const book: Workbook = {
+  종류: "통합문서",
+  판: 1,
+  이름: "harness",
+  서식: [{}],
+  시트: [
+    {
+      id: "s1",
+      이름: "분석",
+      칸: {
+        A1: { 값: "단가" },
+        B1: { 값: "수량" },
+        C1: { 값: "금액" },
+        A2: { 값: 1200 },
+        B2: { 값: 3 },
+        C2: { 식: "A2*B2" },
+        A3: { 값: 800 },
+        B3: { 값: "5" },
+        C3: { 식: "A3*B3" },
+        A4: { 값: 50 },
+        B4: { 값: 0 },
+        C4: { 식: "A4/B4" },
+        C6: { 식: "SUM(C2:C3)+IF(B2>2,C2*10%,0)" },
+        D6: { 식: "C6*2" },
+        E2: { 식: "E3+1" },
+        E3: { 식: "E2+1" },
+      },
+    },
+    { id: "s2", 이름: "요약", 칸: { A1: { 식: "분석!D6" } } },
+  ],
+  활성: "s1",
+};
+
+const host = document.getElementById("host")!;
+w.ss = createSpreadsheet(host, book, { inspect: true });
+const c = w.__aisloSheet as SpreadsheetContext;
+const trace = attachTrace(c);
+const tip = attachErrorTip(c, trace);
+const render = c.grid.render.bind(c.grid);
+c.grid.render = () => {
+  render();
+  trace.refresh();
+  tip.refresh();
+};
+const renderSel = c.grid.renderSelection.bind(c.grid);
+c.grid.renderSelection = () => {
+  renderSel();
+  tip.refresh();
+};
+w.ssCtx = c;
+w.ssTrace = trace;
+w.ssTip = tip;
+w.ssSteps = () => openEvalSteps(c);
+for (const [id, run] of [
+  ["btn-prec", () => trace.precedents()],
+  ["btn-dep", () => trace.dependents()],
+  ["btn-clear", () => trace.clear()],
+  ["btn-steps", () => openEvalSteps(c)],
+] as const)
+  document.getElementById(id)!.addEventListener("click", run);
diff --git a/resources/tester/spreadsheet/harness_analysis_bundle.cjs b/resources/tester/spreadsheet/harness_analysis_bundle.cjs
new file mode 100644
index 00000000..e1c2b08a
--- /dev/null
+++ b/resources/tester/spreadsheet/harness_analysis_bundle.cjs
@@ -0,0 +1,29 @@
+/* 수식 분석 시험 틀 번들 — rolldown(이미 설치) 한 파일 · css 는 <style> 로 넣음 · @ui 별칭.
+ * node harness_analysis_bundle.cjs → tmp/spreadsheet_analysis/harness.js (git 밖) */
+const fs = require("fs");
+const path = require("path");
+const ROOT = path.join(__dirname, "..", "..", "..");
+const { build } = require(path.join(ROOT, "config", "node_modules", "rolldown"));
+
+build({
+  input: path.join(__dirname, "harness_analysis.ts"),
+  resolve: { alias: { "@ui": path.join(ROOT, "ui_template") } },
+  plugins: [
+    {
+      name: "css-inline",
+      load(id) {
+        if (!id.endsWith(".css")) return null;
+        const css = JSON.stringify(fs.readFileSync(id, "utf8"));
+        const code = `const s = document.createElement("style"); s.textContent = ${css}; document.head.append(s);`;
+        return { code, moduleType: "js" };
+      },
+    },
+  ],
+  output: { file: path.join(ROOT, "tmp", "spreadsheet_analysis", "harness.js"), format: "iife" },
+}).then(
+  () => console.log("ok"),
+  (e) => {
+    console.error(e.message);
+    process.exit(1);
+  },
+);
diff --git a/resources/tester/spreadsheet/harness_sortfilter.ts b/resources/tester/spreadsheet/harness_sortfilter.ts
index 6703ba73..0ff2b8c0 100644
--- a/resources/tester/spreadsheet/harness_sortfilter.ts
+++ b/resources/tester/spreadsheet/harness_sortfilter.ts
@@ -1,7 +1,7 @@
 /* 정렬 · 자동 필터 화면 시험 틀 입구 — 진짜 부품(createSpreadsheet)에 정렬 대화 상자 · 필터 단추를 얹음.
- * sub7 잇기 전이라 `parts.mountTabs` 를 감싸 문맥(ctx)을 꺼내고, grid.render 뒤 filter.refresh 를 부름.
+ * sub7 잇기 전이라 `inspect` 로 문맥(ctx)을 꺼내고, grid.render 뒤 filter.refresh 를 부름.
  * 번들: node harness_sortfilter_bundle.cjs → tmp/spreadsheet_sortfilter/harness.js (git 밖) */
-import { createSpreadsheet, parts } from "../../../A00_Common/spreadsheet/spreadsheet";
+import { createSpreadsheet } from "../../../A00_Common/spreadsheet/spreadsheet";
 import {
   openSortDialog,
   sortSelection,
@@ -11,12 +11,6 @@ import type { SpreadsheetContext } from "../../../A00_Common/spreadsheet/spreads
 import type { Workbook } from "../../../A00_Common/spreadsheet/spreadsheet_types";
 
 const w = window as unknown as Record<string, unknown>;
-let ctx: SpreadsheetContext | null = null;
-const origTabs = parts.mountTabs;
-parts.mountTabs = (c: SpreadsheetContext) => {
-  ctx = c;
-  return origTabs(c);
-};
 
 const rows: [string, string, number][] = [
   ["터파기", "토사", 12.5],
@@ -54,9 +48,10 @@ const book: Workbook = {
 
 const host = document.getElementById("host")!;
 w.ss = createSpreadsheet(host, book, {
+  inspect: true,
   onChange: () => (w.ssChanges = Number(w.ssChanges ?? 0) + 1),
 });
-const c = ctx as unknown as SpreadsheetContext;
+const c = w.__aisloSheet as SpreadsheetContext;
 const filter = attachFilter(c);
 const render = c.grid.render.bind(c.grid);
 c.grid.render = () => {
diff --git a/resources/tester/spreadsheet/helper_spreadsheet_analysis.cjs b/resources/tester/spreadsheet/helper_spreadsheet_analysis.cjs
new file mode 100644
index 00000000..0699003b
--- /dev/null
+++ b/resources/tester/spreadsheet/helper_spreadsheet_analysis.cjs
@@ -0,0 +1,167 @@
+/* 수식 분석 엔진 시험 헬퍼 — 추적 화살표 단계 · 수식 계산 걸음 · 오류 검사 까닭을 묶음마다 돌려 틀린 것 목록을 JSON 으로.
+ * 적재 · 가짜 함수는 `helper_spreadsheet_engine.cjs` 것을 씀.
+ */
+const { A, G, load } = require("./helper_spreadsheet_engine.cjs");
+const TR = load("spreadsheet_trace");
+const ST = load("spreadsheet_eval_steps");
+const EC = load("spreadsheet_errcheck");
+
+const results = {};
+let group = "";
+const eq = (label, got, want) => {
+  const g = JSON.stringify(got);
+  const w = JSON.stringify(want);
+  if (g !== w) results[group].push(`${label}: got ${g} want ${w}`);
+};
+const section = (name, fn) => {
+  group = name;
+  results[name] = [];
+  try {
+    fn();
+  } catch (e) {
+    results[name].push(`예외: ${e && e.stack ? e.stack : e}`);
+  }
+};
+
+const cellsOf = (cells) => {
+  const 칸 = {};
+  for (const [k, v] of Object.entries(cells))
+    칸[k] = typeof v === "string" && v.startsWith("=") ? { 식: v.slice(1) } : { 값: v };
+  return 칸;
+};
+function book(cells, sheet2) {
+  const 시트 = [{ id: "s1", 이름: "본", 칸: cellsOf(cells) }];
+  if (sheet2) 시트.push({ id: "s2", 이름: "둘", 칸: cellsOf(sheet2) });
+  return { 종류: "통합문서", 판: 1, 이름: "t", 서식: [{}], 시트 };
+}
+const at = (a1, 시트 = "s1") => ({ 시트, ...A.parseA1(a1) });
+const name = (a) => `${a.시트}!${A.toA1(a.r, a.c)}`;
+const arrowText = (a) =>
+  `${a.from.시트}!${A.rangeToA1(a.from.범위)}>${name(a.to)}${a.오류 ? "!" : ""}`;
+
+// ── 1. 선행 · 종속 추적 ──────────────────────────────────────────────────────
+section("trace", () => {
+  const b = book(
+    { A1: 1, A2: 2, B1: "=A1+A2", C1: "=B1*2", D1: "=SUM(A1:A2)", A3: "=1/0", B3: "=A3+1" },
+    { E1: "=본!C1" },
+  );
+  const e = G.createCalcEngine(b);
+  const st = { arrows: [], opened: new Set() };
+  // 선행: C1 → 한 단계씩
+  eq("선행 1", TR.traceStep(b, e, st, "선행", at("C1")), true);
+  eq("선행 1 화살", st.arrows.map(arrowText), ["s1!B1>s1!C1"]);
+  eq("선행 2", TR.traceStep(b, e, st, "선행", at("C1")), true);
+  eq("선행 2 화살", st.arrows.map(arrowText).slice(1), ["s1!A1>s1!B1", "s1!A2>s1!B1"]);
+  eq("선행 3 더 없음", TR.traceStep(b, e, st, "선행", at("C1")), false);
+
+  // 종속: A1 → B1 · D1(범위로) → C1 → 둘!E1(다른 시트)
+  const sd = { arrows: [], opened: new Set() };
+  TR.traceStep(b, e, sd, "종속", at("A1"));
+  eq("종속 1", sd.arrows.map((a) => name(a.to)).sort(), ["s1!B1", "s1!D1"]);
+  TR.traceStep(b, e, sd, "종속", at("A1"));
+  eq("종속 2", sd.arrows.map((a) => name(a.to)).slice(2), ["s1!C1"]);
+  TR.traceStep(b, e, sd, "종속", at("A1"));
+  eq("종속 3 다른 시트", sd.arrows.map(arrowText).slice(3), ["s1!C1>s2!E1"]);
+  eq("종속 4 더 없음", TR.traceStep(b, e, sd, "종속", at("A1")), false);
+
+  // 범위 선행 · 오류 화살
+  const sr = { arrows: [], opened: new Set() };
+  TR.traceStep(b, e, sr, "선행", at("D1"));
+  eq("범위 화살", sr.arrows.map(arrowText), ["s1!A1:A2>s1!D1"]);
+  const se = { arrows: [], opened: new Set() };
+  TR.traceStep(b, e, se, "선행", at("B3"));
+  eq("오류 칸 화살 빨강", se.arrows.map(arrowText), ["s1!A3>s1!B3!"]);
+  eq("값 칸은 선행 없음", TR.traceStep(b, e, { arrows: [], opened: new Set() }, "선행", at("A1")), false);
+  eq(
+    "dependentsOf",
+    TR.dependentsOf(b, e, "s1", 0, 1).map(name),
+    ["s1!C1"],
+  );
+});
+
+// ── 2. 수식 계산 걸음 ────────────────────────────────────────────────────────
+const stepsOf = (cells, a1) => {
+  const b = book(cells);
+  const e = G.createCalcEngine(b);
+  const p = A.parseA1(a1);
+  return ST.evalSteps(b, e, "s1", p.r, p.c).map((s) =>
+    s.밑줄 ? `${s.글.slice(0, s.밑줄[0])}[${s.글.slice(s.밑줄[0], s.밑줄[1])}]${s.글.slice(s.밑줄[1])}` : s.글,
+  );
+};
+section("eval_steps", () => {
+  eq("차례 · 빈 칸 0 · 범위는 함수가", stepsOf({ A1: 3, A3: 0, B1: "=A1*2+SUM(A1:A3)-A2" }, "B1"), [
+    "[A1]*2+SUM(A1:A3)-A2",
+    "[3*2]+SUM(A1:A3)-A2",
+    "6+[SUM(A1:A3)]-A2",
+    "[6+3]-A2",
+    "9-[A2]",
+    "[9-0]",
+    "9",
+  ]);
+  eq("괄호 안 밑줄", stepsOf({ A1: 3, B1: "=(A1+1)*2" }, "B1"), [
+    "([A1]+1)*2",
+    "([3+1])*2",
+    "[4*2]",
+    "8",
+  ]);
+  eq("IF 는 첫 인자만 먼저 · 안 고른 쪽 오류 무시", stepsOf({ A1: 3, B1: '=IF(A1>2,"큼",1/0)' }, "B1"), [
+    'IF([A1]>2,"큼",1/0)',
+    'IF([3>2],"큼",1/0)',
+    '[IF(TRUE,"큼",1/0)]',
+    '"큼"',
+  ]);
+  eq("글 따옴표", stepsOf({ A1: 'a"b', B1: '=A1&"x"' }, "B1"), [
+    '[A1]&"x"',
+    '["a""b"&"x"]',
+    '"a""bx"',
+  ]);
+  eq("음수 글자는 그대로", stepsOf({ B1: "=-5+1" }, "B1"), ["[-5+1]", "-4"]);
+  eq("오류 전파", stepsOf({ A1: 0, B1: "=1/A1+1" }, "B1"), [
+    "1/[A1]+1",
+    "[1/0]+1",
+    "[#DIV/0!+1]",
+    "#DIV/0!",
+  ]);
+  eq("값 칸은 null", ST.evalSteps(book({ A1: 1 }), G.createCalcEngine(book({ A1: 1 })), "s1", 0, 0), null);
+  eq("상수 식", stepsOf({ B1: "=5" }, "B1"), ["5"]);
+});
+
+// ── 3. 오류 검사 까닭 ────────────────────────────────────────────────────────
+section("errcheck", () => {
+  const b = book({
+    A1: "1,234",
+    A2: "abc",
+    A3: "12a",
+    A4: 5,
+    A5: "=1/0",
+    A6: "=A7",
+    A7: "=A6",
+    A8: " 1e3 ",
+    A9: "=A5+1",
+    A10: "=A4*2",
+  });
+  const e = G.createCalcEngine(b);
+  const w = (a1) => {
+    const p = A.parseA1(a1);
+    const x = EC.cellWarning(b, e, "s1", p.r, p.c);
+    return x && x.종류;
+  };
+  eq(
+    "종류",
+    ["A1", "A2", "A3", "A4", "A5", "A6", "A7", "A8", "A9", "A10", "B1"].map(w),
+    ["글숫자", null, null, null, "오류", "순환", "순환", "글숫자", "오류", null, null],
+  );
+  const why = EC.cellWarning(b, e, "s1", 4, 0).까닭;
+  eq("#DIV/0! 까닭", why.startsWith("#DIV/0! 0 으로 나눔"), true);
+  eq("순환 까닭", EC.cellWarning(b, e, "s1", 5, 0).까닭.includes("A6 → A7"), true);
+  eq("numberLike", ["1,234", " 1e3 ", "1,23", ".5", "-", "+7"].map(EC.numberLike), [
+    1234,
+    1000,
+    null,
+    0.5,
+    null,
+    7,
+  ]);
+});
+
+process.stdout.write(JSON.stringify(results));
diff --git a/resources/tester/spreadsheet/helper_spreadsheet_engine.cjs b/resources/tester/spreadsheet/helper_spreadsheet_engine.cjs
index 144b6699..399f8587 100644
--- a/resources/tester/spreadsheet/helper_spreadsheet_engine.cjs
+++ b/resources/tester/spreadsheet/helper_spreadsheet_engine.cjs
@@ -21,6 +21,7 @@ function loadTs(file) {
   cache.set(full, mod);
   const req = (r) => {
     if (r === "./spreadsheet_functions") return fakeFunctions;
+    if (r.endsWith(".css")) return {};
     if (r.startsWith("@ui/")) return loadTs(path.join(ROOT, "ui_template", `${r.slice(4)}.ts`));
     if (r.startsWith(".")) return loadTs(path.join(path.dirname(full), `${r}.ts`));
     return require(r);
diff --git a/resources/tester/spreadsheet/spreadsheet_b_test_entry.ts b/resources/tester/spreadsheet/spreadsheet_b_test_entry.ts
index 129b4d08..068901cf 100644
--- a/resources/tester/spreadsheet/spreadsheet_b_test_entry.ts
+++ b/resources/tester/spreadsheet/spreadsheet_b_test_entry.ts
@@ -294,6 +294,117 @@ errEq("NA", call("NA"), "#N/A");
   fracEq("YEAR(TODAY()) = 지금 연도", call("YEAR", lit(todaySerial)), String(wantYear));
 }
 
+// ── 통계(3차) ────────────────────────────────────────────────────────────
+
+fracEq("MEDIAN 홀수", call("MEDIAN", n(1), n(2), n(3), n(4), n(5)), "3");
+fracEq("MEDIAN 짝수", call("MEDIAN", n(1), n(2), n(3), n(4)), "2.5");
+fracEq("MODE 최빈값", call("MODE", n(1), n(2), n(2), n(3), n(3), n(3)), "3");
+errEq("MODE 겹침 없음", call("MODE", n(1), n(2), n(3)), "#N/A");
+fracEq("VAR 표본분산", call("VAR", n(1), n(2), n(3)), "1");
+fracEq("STDEV 표본표준편차", call("STDEV", n(1), n(2), n(3)), "1");
+fracEq("STDEV.S", call("STDEV.S", n(1), n(2), n(3)), "1");
+fracEq("STDEV.P 모표준편차", call("STDEV.P", n(2), n(4), n(4), n(4), n(5), n(5), n(7), n(9)), "2");
+{
+  const RANKS = range(1, 4, [[frac(10n), frac(20n), frac(30n), frac(40n)]]);
+  fracEq("RANK 내림차순(기본)", call("RANK", n(30), RANKS), "2");
+  fracEq("RANK 오름차순", call("RANK", n(30), RANKS, n(1)), "3");
+  fracEq("RANK.EQ", call("RANK.EQ", n(30), RANKS), "2");
+  errEq("RANK 없는 값", call("RANK", n(99), RANKS), "#N/A");
+  fracEq("LARGE 1위", call("LARGE", RANKS, n(1)), "40");
+  fracEq("LARGE 2위", call("LARGE", RANKS, n(2)), "30");
+  fracEq("SMALL 1위", call("SMALL", RANKS, n(1)), "10");
+  errEq("LARGE 범위밖", call("LARGE", RANKS, n(9)), "#NUM!");
+}
+{
+  const NUMS4 = range(1, 4, [[frac(1n), frac(2n), frac(3n), frac(4n)]]);
+  fracEq("PERCENTILE 중간", call("PERCENTILE", NUMS4, n("0.5")), "2.5");
+  fracEq("PERCENTILE 0", call("PERCENTILE", NUMS4, n(0)), "1");
+  fracEq("PERCENTILE 1", call("PERCENTILE", NUMS4, n(1)), "4");
+  fracEq("QUARTILE 중앙값(2)", call("QUARTILE", NUMS4, n(2)), "2.5");
+  fracEq("QUARTILE 최솟값(0)", call("QUARTILE", NUMS4, n(0)), "1");
+  errEq("QUARTILE 범위밖", call("QUARTILE", NUMS4, n(9)), "#NUM!");
+}
+fracEq("COUNTBLANK", call("COUNTBLANK", range(1, 4, [[frac(1n), null, "x", null]])), "2");
+
+// ── 날짜 · 시간(3차) ──────────────────────────────────────────────────────
+
+function dateSerial(y: number, m: number, day: number): EvalResult {
+  return call("DATE", n(y), n(m), n(day));
+}
+
+{
+  const serial = dateSerial(2026, 3, 15);
+  const wantDow = new Date(Date.UTC(2026, 2, 15)).getUTCDay(); // 0=일..6=토
+  fracEq("WEEKDAY 기본(1=일)", call("WEEKDAY", lit(serial)), String(wantDow + 1));
+  fracEq(
+    "WEEKDAY 유형2(1=월)",
+    call("WEEKDAY", lit(serial), n(2)),
+    String(((wantDow + 6) % 7) + 1),
+  );
+}
+{
+  // 월말 넘침 — 1/31 + 1개월은 다음 달로 안 넘고 그 달 말일(2/28)로.
+  const edated = call("EDATE", lit(dateSerial(2026, 1, 31)), n(1));
+  fracEq("EDATE 월말 눌러담음(월)", call("MONTH", lit(edated)), "2");
+  fracEq("EDATE 월말 눌러담음(일)", call("DAY", lit(edated)), "28");
+  const normal = call("EDATE", lit(dateSerial(2026, 1, 15)), n(1));
+  fracEq("EDATE 평범한 경우(일)", call("DAY", lit(normal)), "15");
+}
+{
+  const eom = call("EOMONTH", lit(dateSerial(2026, 2, 10)), n(0));
+  fracEq("EOMONTH 이번달 말일", call("DAY", lit(eom)), "28");
+  const eomNext = call("EOMONTH", lit(dateSerial(2026, 2, 10)), n(1));
+  fracEq("EOMONTH 다음달 말일", call("DAY", lit(eomNext)), "31");
+}
+fracEq(
+  "DATEDIF Y",
+  call("DATEDIF", lit(dateSerial(2020, 1, 1)), lit(dateSerial(2023, 1, 1)), txt("Y")),
+  "3",
+);
+fracEq(
+  "DATEDIF Y(생일 전)",
+  call("DATEDIF", lit(dateSerial(2020, 6, 15)), lit(dateSerial(2023, 1, 1)), txt("Y")),
+  "2",
+);
+fracEq(
+  "DATEDIF M",
+  call("DATEDIF", lit(dateSerial(2020, 1, 1)), lit(dateSerial(2023, 1, 1)), txt("M")),
+  "36",
+);
+fracEq(
+  "DATEDIF D",
+  call("DATEDIF", lit(dateSerial(2024, 1, 1)), lit(dateSerial(2024, 1, 31)), txt("D")),
+  "30",
+);
+errEq(
+  "DATEDIF 끝이 이름(#NUM!)",
+  call("DATEDIF", lit(dateSerial(2024, 1, 10)), lit(dateSerial(2024, 1, 1)), txt("D")),
+  "#NUM!",
+);
+{
+  const wantMon = new Date(Date.UTC(2024, 0, 1)).getUTCDay() === 1;
+  ok("2024-01-01 은 월요일(전제)", wantMon);
+  const nw = call("NETWORKDAYS", lit(dateSerial(2024, 1, 1)), lit(dateSerial(2024, 1, 7)));
+  fracEq("NETWORKDAYS 한 주", nw, "5");
+  const nwHoliday = call(
+    "NETWORKDAYS",
+    lit(dateSerial(2024, 1, 1)),
+    lit(dateSerial(2024, 1, 7)),
+    lit(dateSerial(2024, 1, 3)),
+  );
+  fracEq("NETWORKDAYS 휴일 뺌", nwHoliday, "4");
+}
+fracEq("HOUR", call("HOUR", lit(call("TIME", n(13), n(45), n(30)))), "13");
+fracEq("MINUTE", call("MINUTE", lit(call("TIME", n(13), n(45), n(30)))), "45");
+{
+  const t = call("TIME", n(6), n(0), n(0));
+  ok(
+    "TIME(6,0,0) = 0.25",
+    isFrac(t) && fracToString(t) === "0.25",
+    isFrac(t) ? fracToString(t) : String(t),
+  );
+}
+
 // ── 숫자 형식 ────────────────────────────────────────────────────────────
 
 function fmt(value: Scalar, code: string): string {
@@ -346,6 +457,21 @@ ok(
 );
 ok("분수 분모 고정", fmt(frac(4n, 10n), "# ?/8") === " 3/8", fmt(frac(4n, 10n), "# ?/8"));
 ok("분수 정확히 나눠떨어짐(정수만)", fmt(frac(3n), "# ?/?") === "3", fmt(frac(3n), "# ?/?"));
+// 날짜 형식(3차)
+{
+  const serial = dateSerial(2026, 3, 5) as Scalar;
+  ok("yyyy-mm-dd", fmt(serial, "yyyy-mm-dd") === "2026-03-05", fmt(serial, "yyyy-mm-dd"));
+  ok("m/d(자리 없는 달·일)", fmt(serial, "m/d") === "3/5", fmt(serial, "m/d"));
+  const wd = new Date(Date.UTC(2026, 2, 5)).getUTCDay();
+  const WEEKDAY_SHORT = ["일", "월", "화", "수", "목", "금", "토"];
+  ok(
+    "요일 aaa",
+    fmt(serial, "aaa") === WEEKDAY_SHORT[wd],
+    `got=${fmt(serial, "aaa")} want=${WEEKDAY_SHORT[wd]}`,
+  );
+  ok("요일 aaaa", fmt(serial, "aaaa") === `${WEEKDAY_SHORT[wd]}요일`, fmt(serial, "aaaa"));
+}
+
 ok("글자 형식 @", fmt("abc", "@@") === "abcabc", fmt("abc", "@@"));
 ok(
   "일반(General)",
diff --git a/resources/tester/spreadsheet/spreadsheet_grid_test.ts b/resources/tester/spreadsheet/spreadsheet_grid_test.ts
index ed13e30c..d732dea1 100644
--- a/resources/tester/spreadsheet/spreadsheet_grid_test.ts
+++ b/resources/tester/spreadsheet/spreadsheet_grid_test.ts
@@ -156,6 +156,7 @@ ctx.root.append(grid.root);
   grid,
   sheet,
   book,
+  ctx,
   colIndex,
   countCells: () => grid.root.querySelectorAll(".aislo-cell").length,
 };
diff --git a/resources/tester/spreadsheet/test_spreadsheet_analysis.py b/resources/tester/spreadsheet/test_spreadsheet_analysis.py
new file mode 100644
index 00000000..2a736f48
--- /dev/null
+++ b/resources/tester/spreadsheet/test_spreadsheet_analysis.py
@@ -0,0 +1,36 @@
+# -*- coding: utf-8 -*-
+"""산출근거 스프레드시트 수식 분석 — 엑셀 규칙표.
+
+선행 · 종속 추적(누를 때마다 한 단계 · 범위 화살 · 오류 칸 빨강 · 다른 시트 · 더 없으면 false) ·
+수식 계산 걸음(왼쪽 먼저 · 빈 칸 0 · 범위는 함수가 · IF 첫 인자만 · 괄호 안 밑줄 · 오류 전파) ·
+오류 검사(순환 · 식 결과 오류 · 숫자처럼 보이는 글).
+화면(화살 겹판 · 계산 창 · ⚠ 풍선)은 harness_analysis.html 을 ORCA 로.
+"""
+
+import json
+import os
+import subprocess
+
+import pytest
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+GROUPS = ["trace", "eval_steps", "errcheck"]
+
+
+@pytest.fixture(scope="module")
+def results():
+    proc = subprocess.run(
+        ["node", os.path.join(HERE, "helper_spreadsheet_analysis.cjs")],
+        capture_output=True,
+        text=True,
+        encoding="utf-8",
+        timeout=120,
+    )
+    assert proc.returncode == 0, proc.stderr
+    return json.loads(proc.stdout)
+
+
+@pytest.mark.parametrize("group", GROUPS)
+def test_묶음(results, group):
+    assert group in results
+    assert results[group] == []
diff --git a/resources/tester/spreadsheet/test_stage3_autosum.ts b/resources/tester/spreadsheet/test_stage3_autosum.ts
new file mode 100644
index 00000000..f0736521
--- /dev/null
+++ b/resources/tester/spreadsheet/test_stage3_autosum.ts
@@ -0,0 +1,60 @@
+/* =============================================================================
+ * test_stage3_autosum.ts — spreadsheet_autosum 시험. 돌리기: npx tsx <이 파일>.
+ * ========================================================================== */
+
+import { applyAutoSum, autoSumRange } from "../../../A00_Common/spreadsheet/spreadsheet_autosum.ts";
+import { assertEqual, fracLiteral, makeBook, makeCtx, makeSheet } from "./test_stage2_helpers.ts";
+
+// 위로 연속 숫자 셋 — A1,A2,A3 숫자 · A4(활성) 빈칸
+const sheet = makeSheet("s1", {});
+const book = makeBook([sheet]);
+const ctxUp = makeCtx(book, "s1", {
+  s1: { A1: fracLiteral(1), A2: fracLiteral(2), A3: fracLiteral(3) },
+});
+ctxUp.selection.활성 = { r: 3, c: 0 };
+ctxUp.selection.범위 = [{ r0: 3, c0: 0, r1: 3, c1: 0 }];
+assertEqual(autoSumRange(ctxUp), { r0: 0, c0: 0, r1: 2, c1: 0 }, "위로 연속 숫자를 잡음");
+
+applyAutoSum(ctxUp);
+assertEqual(
+  ctxUp.applied.at(-1),
+  { 종류: "칸", 시트: "s1", 칸: { A4: { 식: "SUM(A1:A3)" } } },
+  "applyAutoSum 이 칸 명령을 냄",
+);
+
+// 위가 빈칸 · 왼쪽으로 연속 숫자 — B1,C1 숫자 · D1(활성)
+const ctxLeft = makeCtx(book, "s1", {
+  s1: { B1: fracLiteral(5), C1: fracLiteral(7) },
+});
+ctxLeft.selection.활성 = { r: 0, c: 3 };
+ctxLeft.selection.범위 = [{ r0: 0, c0: 3, r1: 0, c1: 3 }];
+assertEqual(
+  autoSumRange(ctxLeft),
+  { r0: 0, c0: 1, r1: 0, c1: 2 },
+  "위가 없으면 왼쪽 연속 숫자를 잡음",
+);
+
+// 위 · 왼쪽 다 없음 — null
+const ctxNone = makeCtx(book, "s1");
+ctxNone.selection.활성 = { r: 5, c: 5 };
+ctxNone.selection.범위 = [{ r0: 5, c0: 5, r1: 5, c1: 5 }];
+assertEqual(autoSumRange(ctxNone), null, "위 · 왼쪽 다 없으면 null");
+applyAutoSum(ctxNone);
+assertEqual(
+  ctxNone.applied.at(-1),
+  { 종류: "칸", 시트: "s1", 칸: { F6: { 식: "SUM()" } } },
+  "찾은 범위가 없으면 빈 SUM()",
+);
+
+// 여러 칸을 고른 채 — 활성이 맨 아래일 때 그 고름 안 위쪽만 잡음(가운데 빈칸이 있어도)
+const ctxSel = makeCtx(book, "s1", { s1: { A10: fracLiteral(1), A11: fracLiteral(2) } });
+ctxSel.selection.활성 = { r: 11, c: 0 };
+ctxSel.selection.범위 = [{ r0: 9, c0: 0, r1: 11, c1: 0 }];
+assertEqual(
+  autoSumRange(ctxSel),
+  { r0: 9, c0: 0, r1: 10, c1: 0 },
+  "고른 범위 안에서 활성 위만 잡음",
+);
+
+if (process.exitCode) process.exit(process.exitCode);
+console.log("spreadsheet_autosum 시험 끝");
diff --git a/resources/tester/spreadsheet/test_stage3_sheet_extra.ts b/resources/tester/spreadsheet/test_stage3_sheet_extra.ts
new file mode 100644
index 00000000..529fde3c
--- /dev/null
+++ b/resources/tester/spreadsheet/test_stage3_sheet_extra.ts
@@ -0,0 +1,36 @@
+/* =============================================================================
+ * test_stage3_sheet_extra.ts — spreadsheet_sheet_extra 시험. 돌리기: npx tsx <이 파일>.
+ * ========================================================================== */
+
+import {
+  hideSheet,
+  setSheetTabColor,
+  unhideSheet,
+} from "../../../A00_Common/spreadsheet/spreadsheet_sheet_extra.ts";
+import { assertEqual, makeBook, makeCtx, makeSheet } from "./test_stage2_helpers.ts";
+
+const s1 = makeSheet("s1", {});
+const s2 = makeSheet("s2", {});
+const book = makeBook([s1, s2]);
+book.활성 = "s1";
+const shown: string[] = [];
+const ctx = { ...makeCtx(book, "s1"), showSheet: (id: string) => shown.push(id) };
+
+assertEqual(hideSheet(ctx, "s1"), null, "hideSheet 성공 — 까닭 없음");
+assertEqual(book.시트[0].숨김, true, "s1 이 숨겨짐");
+assertEqual(ctx.applied.at(-1)?.종류, "시트통째", "hideSheet 은 시트통째로 나감");
+assertEqual(shown, ["s2"], "활성 시트를 숨기면 다른 보이는 시트로 옮김");
+
+assertEqual(hideSheet(ctx, "s2"), "마지막 보이는 시트는 못 숨김", "마지막 보이는 시트는 거절");
+assertEqual(book.시트[1].숨김, undefined, "거절되면 안 바뀜");
+
+unhideSheet(ctx, "s1");
+assertEqual(book.시트[0].숨김, false, "unhideSheet 로 다시 보임");
+
+setSheetTabColor(ctx, "s2", "#ff0000");
+assertEqual(book.시트[1].탭색, "#ff0000", "탭 색 지정");
+setSheetTabColor(ctx, "s2", null);
+assertEqual(book.시트[1].탭색, undefined, "탭 색 지움");
+
+if (process.exitCode) process.exit(process.exitCode);
+console.log("spreadsheet_sheet_extra 시험 끝");
diff --git a/resources/tester/spreadsheet/test_stage3_statusbar.ts b/resources/tester/spreadsheet/test_stage3_statusbar.ts
new file mode 100644
index 00000000..e4e6aa19
--- /dev/null
+++ b/resources/tester/spreadsheet/test_stage3_statusbar.ts
@@ -0,0 +1,47 @@
+/* =============================================================================
+ * test_stage3_statusbar.ts — spreadsheet_statusbar 시험. 돌리기: npx tsx <이 파일>.
+ * ========================================================================== */
+
+import { computeSelectionStats } from "../../../A00_Common/spreadsheet/spreadsheet_statusbar.ts";
+import {
+  assertEqual,
+  fracLiteral,
+  makeBook,
+  makeCtx,
+  makeSheet,
+  v,
+} from "./test_stage2_helpers.ts";
+
+const sheet = makeSheet("s1", { A1: v("사과"), A2: v("배") });
+const book = makeBook([sheet]);
+
+const ctx = makeCtx(book, "s1", {
+  s1: { A1: fracLiteral(10), A2: fracLiteral(20), A3: "글자" },
+});
+ctx.selection.범위 = [{ r0: 0, c0: 0, r1: 2, c1: 0 }];
+
+const stats = computeSelectionStats(ctx);
+assertEqual(stats.합계, 10 + 20, "합계 — 숫자만 더함");
+assertEqual(stats.평균, 15, "평균");
+assertEqual(stats.개수, 3, "개수 — 빈칸 아닌 칸 전부(COUNTA)");
+assertEqual(stats.숫자개수, 2, "숫자개수 — 숫자만(COUNT)");
+assertEqual(stats.최소, 10, "최소");
+assertEqual(stats.최대, 20, "최대");
+
+// 빈 범위 — 다 null · 0
+const empty = makeCtx(book, "s1");
+empty.selection.범위 = [{ r0: 5, c0: 5, r1: 5, c1: 5 }];
+const emptyStats = computeSelectionStats(empty);
+assertEqual(emptyStats.합계, null, "빈 범위 합계는 null");
+assertEqual(emptyStats.개수, 0, "빈 범위 개수는 0");
+
+// 겹치는 범위는 한 번만 셈
+const overlap = makeCtx(book, "s1", { s1: { A1: fracLiteral(5) } });
+overlap.selection.범위 = [
+  { r0: 0, c0: 0, r1: 0, c1: 0 },
+  { r0: 0, c0: 0, r1: 0, c1: 0 },
+];
+assertEqual(computeSelectionStats(overlap).숫자개수, 1, "겹치는 범위는 한 번만 셈");
+
+if (process.exitCode) process.exit(process.exitCode);
+console.log("spreadsheet_statusbar 시험 끝");