diff --git a/B09_Estimation/B09_Estimation_Contract.py b/B09_Estimation/B09_Estimation_Contract.py
new file mode 100644
index 00000000..5eacf158
--- /dev/null
+++ b/B09_Estimation/B09_Estimation_Contract.py
@@ -0,0 +1,204 @@
+"""B09 계약 단계 — 당초설계 → 계약내역 (PLAN 12장 「설계 뒤 네 단계」 · 2026-09-14 브레인 배정).
+
+근거: STmate 분석 `27_계약_실행_기성_단계.md` §2 (`wM_Mk_Cont`) ·
+      `35_형식과_단계의_공통과_차이.md` §3.
+    · 낙찰률 하나가 아니라 **노무·재료·경비별 단가 적용률**
+    · 옵션 여섯(아래 `OPTIONS` — 화면 표기 그대로)
+    · **행별 적용 제외**(「적용율을 제외할(ex 관급자재대..) 공정을 선택」)
+    · 0% 이면 계약단가(W코드)를 「0」化 — 빈 줄이 아니라 **공내역** 줄
+
+⚠ **설계를 안 건드린다** — 설계 내역(`/estimation/bill`) 줄을 **복사해** 적용률을 얹는다.
+  설계 내역·원가계산서·골든셋은 그대로다.
+⚠ **값이 맞다가 아니라 구조가 선다까지** — 계약 표본 0건(27번 §9)이라 원 단위로 못 맞춰 봄.
+  절사는 설계 내역과 같은 규칙(`bill_line` — 성분 단가 원 미만 · 줄 성분마다 절사)을 빌려 씀.
+"""
+
+from __future__ import annotations
+
+from decimal import Decimal, InvalidOperation
+from typing import Any
+
+# ⚠ `_Rows` 를 먼저 부르면 순환 import — 설계 내역 본체가 다시 내보내는 자리에서 받음.
+from B09_Estimation.B09_Estimation_BillOfQuantities import bill_line
+from B09_Estimation.B09_Estimation_PriceBook import Money3
+
+_ZERO = Decimal(0)
+_HUNDRED = Decimal(100)
+
+#: 저장 자리 — `estimation` 구획 안 한 칸.
+SETTINGS_KEY = "contract"
+
+#: 단가 적용률 — STmate 【 노 】【 재 】【 경 】 차례.
+RATE_FIELDS: tuple[tuple[str, str], ...] = (
+    ("labor_pct", "노"),
+    ("material_pct", "재"),
+    ("expense_pct", "경"),
+)
+
+#: 적용 옵션 — 화면 표기 그대로(27번 §2.2). 뜻이 확인 안 된 것은 칸만 받고 까닭을 적음.
+OPTIONS: tuple[tuple[str, str], ...] = (
+    ("apply_to_base_prices", "기초단가(재,노,경,일식)에 단가적용율 적용하기"),
+    ("generate_unit_prices", "적용율 적용된 일위대가/산출근거 생성하기"),
+    ("separate_same_code", "계약내역내 동일코드의 계약단가 개별생성"),
+    ("labor_ratio", "노무비율 적용"),
+    ("tax_free_material", "비과세자재대(원가계산)에 단가적용율 적용하기"),
+    ("zero_makes_empty", '단가적용율이 0% 이면 계약단가(W코드)를 "0"化 (공내역 생성)'),
+)
+#: 계산에 아직 안 쓰는 옵션과 그 까닭 — 조용히 무시하지 않고 화면에 적음.
+OPTION_NOT_USED = {
+    "apply_to_base_prices": (
+        "기초단가(자재·노임·중기) 수준 적용은 다음 차례 — 지금은 일위대가 성분에 적용"
+    ),
+    "generate_unit_prices": "계약 일위대가·산출근거 표 생성은 다음 차례",
+    "labor_ratio": (
+        "「노무비 비율 별도」의 계산 뜻이 분석 자료에서 확인 안 됨(27번 §2.2) — 칸만 받음"
+    ),
+    "tax_free_material": "비과세자재대 줄이 아직 원가계산서에 없음 — 칸만 받음",
+}
+
+
+def _pct(value: Any) -> Decimal | None:
+    try:
+        number = Decimal(str(value))
+    except (InvalidOperation, ValueError):
+        return None
+    return number if number >= 0 else None
+
+
+def clean_settings(values: dict[str, Any]) -> tuple[dict[str, Any], list[str]]:
+    """저장값과 거른 까닭. 적용률은 0 이상 수 · 비면 100(적용 안 함과 같음)."""
+    errors: list[str] = []
+    cleaned: dict[str, Any] = {}
+    for key, label in RATE_FIELDS:
+        raw = values.get(key)
+        if raw in (None, ""):
+            cleaned[key] = "100"
+            continue
+        pct = _pct(raw)
+        if pct is None:
+            errors.append(f"【{label}】 적용률이 0 이상 수가 아님 — {raw}")
+            continue
+        cleaned[key] = str(pct)
+    for key, _ in OPTIONS:
+        cleaned[key] = bool(values.get(key))
+    cleaned["excluded"] = sorted({str(item) for item in values.get("excluded") or [] if item})
+    return cleaned, errors
+
+
+def _money(value: Any) -> Decimal:
+    return Decimal(str(value)) if value not in (None, "") else _ZERO
+
+
+def contract_bill(bill_rows: list[dict[str, Any]], settings: dict[str, Any]) -> dict[str, Any]:
+    """설계 내역 줄(`BillRow.as_dict`) → 계약내역 줄 · 합계 · 까닭.
+
+    ⚠ 0% 처리(판정 대기): 「공내역 생성」을 켜면 그 성분이 0 원(세 성분 모두 0 이면 공내역 줄).
+      끄면 0% 를 「적용 안 함」으로 봄 — STmate 가 따로 옵션을 둔 까닭으로 읽은 것(표본 없음).
+    """
+    rates = {key: _pct(settings.get(key, "100")) or _ZERO for key, _ in RATE_FIELDS}
+    zero_empty = bool(settings.get("zero_makes_empty"))
+    separate = bool(settings.get("separate_same_code"))
+    excluded = {str(item) for item in settings.get("excluded") or []}
+
+    def factor(key: str) -> Decimal:
+        pct = rates[key]
+        if pct == 0 and not zero_empty:
+            return Decimal(1)  # 0% = 적용 안 함(공내역 옵션 꺼짐)
+        return pct / _HUNDRED
+
+    rows: list[dict[str, Any]] = []
+    design = Money3()
+    contract = Money3()
+    for source in bill_rows:
+        row = dict(source)
+        if row.get("is_group") or not row.get("in_bill", True):
+            rows.append(row)
+            continue
+        unit_design = Money3(
+            material=_money(row.get("unit_material_krw")),
+            labor=_money(row.get("unit_labor_krw")),
+            expense=_money(row.get("unit_expense_krw")),
+        )
+        quantity = row.get("quantity")
+        if quantity in (None, "") or row.get("unit_material_krw") is None:
+            row.update(contract_note="설계 단가가 안 선 줄 — 계약단가도 못 섬", contract_code="")
+            rows.append(row)
+            continue
+        qty = Decimal(str(quantity))
+        design_line = bill_line(unit_design, qty)
+        design += design_line
+        base_code = str(row.get("price_code") or row.get("code") or "")
+        if str(row.get("item_no")) in excluded:
+            unit, code, note = unit_design, base_code, "적용 제외 — 설계 단가 그대로"
+        else:
+            unit = Money3(
+                material=unit_design.material * factor("material_pct"),
+                labor=unit_design.labor * factor("labor_pct"),
+                expense=unit_design.expense * factor("expense_pct"),
+            ).floored(Decimal(1))
+            suffix = f"@{row.get('item_no')}" if separate else ""
+            code = f"W-{base_code}{suffix}"
+            note = "공내역 — 적용률 0%" if unit.total == 0 and zero_empty else ""
+        line = bill_line(unit, qty)
+        contract += line
+        row.update(
+            contract_code=code,
+            contract_unit_material_krw=str(unit.material),
+            contract_unit_labor_krw=str(unit.labor),
+            contract_unit_expense_krw=str(unit.expense),
+            contract_unit_price_krw=str(unit.total),
+            contract_material_krw=str(line.material),
+            contract_labor_krw=str(line.labor),
+            contract_expense_krw=str(line.expense),
+            contract_amount_krw=str(line.total),
+            contract_excluded=str(row.get("item_no")) in excluded,
+            contract_note=note,
+        )
+        rows.append(row)
+    _group_sums(rows)
+    return {
+        "rows": rows,
+        "totals": {
+            "design": _totals(design),
+            "contract": _totals(contract),
+            "ratio_pct": {
+                part: str(
+                    (getattr(contract, part) / getattr(design, part) * _HUNDRED).quantize(
+                        Decimal("0.001")
+                    )
+                )
+                if getattr(design, part)
+                else None
+                for part in ("material", "labor", "expense")
+            },
+        },
+        "options_not_used": {k: v for k, v in OPTION_NOT_USED.items() if settings.get(k)},
+    }
+
+
+def _totals(money: Money3) -> dict[str, str]:
+    return {
+        "material_krw": str(money.material),
+        "labor_krw": str(money.labor),
+        "expense_krw": str(money.expense),
+        "total_krw": str(money.total),
+    }
+
+
+def _group_sums(rows: list[dict[str, Any]]) -> None:
+    """묶음 줄 계약 금액 — 아래 줄의 합(설계 내역 `_group_sums` 와 같은 꼴)."""
+    for group in rows:
+        if not group.get("is_group"):
+            continue
+        prefix = f"{group.get('item_no')}."
+        children = [
+            r
+            for r in rows
+            if not r.get("is_group")
+            and str(r.get("item_no", "")).startswith(prefix)
+            and r.get("contract_amount_krw") is not None
+        ]
+        for part in ("material", "labor", "expense", "amount"):
+            group[f"contract_{part}_krw"] = str(
+                sum((Decimal(r[f"contract_{part}_krw"]) for r in children), _ZERO)
+            )
diff --git a/B09_Estimation/B09_Estimation_Router_Contract.py b/B09_Estimation/B09_Estimation_Router_Contract.py
new file mode 100644
index 00000000..a5ab9e1b
--- /dev/null
+++ b/B09_Estimation/B09_Estimation_Router_Contract.py
@@ -0,0 +1,95 @@
+"""B09 계약 단계 탭 API — 당초설계 → 계약내역 (PLAN 12장 · 랩탑 메인).
+
+⚠ 설계 내역을 **읽기만** 한다(`/estimation/bill` 결과를 복사해 적용률을 얹음). 저장은
+  `estimation.contract` 한 칸 — 설계 내역·원가계산서 저장본은 안 건드린다.
+"""
+
+from __future__ import annotations
+
+import json
+import logging
+from typing import Any
+from uuid import UUID
+
+from fastapi import APIRouter
+from fastapi.responses import JSONResponse
+
+from B09_Estimation.B09_Estimation_Contract import (
+    OPTIONS,
+    RATE_FIELDS,
+    SETTINGS_KEY,
+    clean_settings,
+    contract_bill,
+)
+
+logger = logging.getLogger(__name__)
+router = APIRouter(prefix="/api/projects", tags=["B09 Estimation — Contract"])
+
+
+async def _root(project_id: UUID) -> str | None:
+    from B09_Estimation.B09_Estimation_Router import _project_root_of
+
+    return await _project_root_of(project_id)
+
+
+@router.get("/{project_id}/estimation/contract")
+async def get_contract(project_id: UUID) -> JSONResponse:
+    """계약내역 한 장 — 설계 줄 옆에 계약단가·계약금액 · 설계↔계약 합계 · 옵션."""
+    from B09_Estimation.B09_Estimation_Router import get_bill
+    from common_util.common_util_project_settings import estimation_settings
+
+    root = await _root(project_id)
+    if root is None:
+        return JSONResponse(
+            status_code=404,
+            content={"status": "error", "message": "프로젝트 저장 폴더를 찾지 못했습니다."},
+        )
+    response = await get_bill(project_id)
+    bill = json.loads(bytes(response.body).decode("utf-8"))
+    if response.status_code != 200 or "rows" not in bill:
+        return JSONResponse(status_code=response.status_code or 502, content=bill)
+    stored, _ = clean_settings(dict(estimation_settings(root).get(SETTINGS_KEY) or {}))
+    result = contract_bill(bill["rows"], stored)
+    return JSONResponse(
+        content={
+            "status": "success",
+            **result,
+            "settings": stored,
+            "fields": {
+                "rates": [{"key": k, "label": label} for k, label in RATE_FIELDS],
+                "options": [{"key": k, "label": label} for k, label in OPTIONS],
+            },
+            "bill_missing_count": len((bill.get("summary") or {}).get("missing") or []),
+            "limit_note": (
+                "계약 표본 0건 — 구조가 서는지까지만 확인됨 · 원 단위 값은 표본이 생기면 대조"
+            ),
+        }
+    )
+
+
+@router.put("/{project_id}/estimation/contract")
+async def put_contract(project_id: UUID, body: dict[str, Any]) -> JSONResponse:
+    """적용률·옵션·적용 제외 줄 저장 — 틀린 칸이 있으면 아무것도 안 저장."""
+    from common_util.common_util_project_settings import save_section
+
+    root = await _root(project_id)
+    if root is None:
+        return JSONResponse(
+            status_code=404,
+            content={"status": "error", "message": "프로젝트 저장 폴더를 찾지 못했습니다."},
+        )
+    cleaned, errors = clean_settings(body)
+    if errors:
+        return JSONResponse(
+            status_code=400,
+            content={"status": "error", "message": " · ".join(errors), "errors": errors},
+        )
+    try:
+        save_section(root, "estimation", {SETTINGS_KEY: cleaned}, replace_keys=(SETTINGS_KEY,))
+    except Exception:
+        logger.exception("B09 계약 조건 저장 실패: project_id=%s", project_id)
+        return JSONResponse(
+            status_code=500,
+            content={"status": "error", "message": "계약 조건을 저장하지 못했습니다."},
+        )
+    return JSONResponse(content={"status": "success", "settings": cleaned})
diff --git a/B09_Estimation/B09_Estimation_UI_Tab_Contract.ts b/B09_Estimation/B09_Estimation_UI_Tab_Contract.ts
new file mode 100644
index 00000000..6c1ee501
--- /dev/null
+++ b/B09_Estimation/B09_Estimation_UI_Tab_Contract.ts
@@ -0,0 +1,300 @@
+/* =============================================================================
+ * B09_Estimation_UI_Tab_Contract.ts
+ * 계약내역 탭 — STmate 「당초설계 → 계약내역 변환등록」(wM_Mk_Cont)을 본뜸 (PLAN 12장 · 랩탑 메인).
+ *
+ *   - 좌측 = 단가 적용율 【 노 】【 재 】【 경 】 % · 적용 옵션 여섯(화면 표기 그대로) · [저장].
+ *   - 본문 = 공종번호 · 명칭 · 규격 · 금액(설계) · 계약 단가·금액 · **적용제외** · 계약단가 코드.
+ *   - ⚠ 값은 서버(`/estimation/contract`)가 설계 내역을 복사해 셈 — 설계는 안 바뀜.
+ *   - ⚠ 계약 표본이 없어 「구조가 선다」까지만 확인된 화면 — 머리에 그 한계를 적음.
+ * ========================================================================== */
+
+import { ui_locales, currentLanguageIndex } from "@ui/ui_template_locale";
+import { createButton, showToast } from "@ui/ui_template_elements";
+import { API_BASE_URL } from "@config/config_frontend";
+import type { B09Tab, B09TabContext } from "./B09_Estimation_UI_Shell_Types";
+
+function L(key: keyof typeof ui_locales): string {
+  return ui_locales[key][currentLanguageIndex];
+}
+
+interface ContractRow {
+  item_no: string;
+  name: string;
+  spec: string;
+  unit: string;
+  quantity: string | null;
+  is_group: boolean;
+  in_bill: boolean;
+  amount_krw: string | null;
+  contract_unit_price_krw?: string;
+  contract_amount_krw?: string;
+  contract_code?: string;
+  contract_excluded?: boolean;
+  contract_note?: string;
+}
+
+interface Money {
+  material_krw: string;
+  labor_krw: string;
+  expense_krw: string;
+  total_krw: string;
+}
+
+interface ContractDto {
+  status: string;
+  message?: string;
+  rows: ContractRow[];
+  totals: { design: Money; contract: Money; ratio_pct: Record<string, string | null> };
+  options_not_used: Record<string, string>;
+  settings: Record<string, string | boolean | string[]>;
+  fields: {
+    rates: { key: string; label: string }[];
+    options: { key: string; label: string }[];
+  };
+  bill_missing_count: number;
+  limit_note: string;
+}
+
+const STYLE_ID = "b09-contract-styles";
+function injectStyles(): void {
+  if (document.getElementById(STYLE_ID)) return;
+  const style = document.createElement("style");
+  style.id = STYLE_ID;
+  style.textContent = `
+.b09ct { display: flex; flex-direction: column; gap: 8px; height: 100%; min-height: 0; }
+.b09ct__meta { font-size: 12px; color: var(--color-text-secondary); }
+.b09ct__warn { font-size: 12px; color: var(--color-warning-text, #8a5a00); }
+.b09ct__scroll { flex: 1; overflow: auto; min-height: 0; }
+.b09ct__table { border-collapse: collapse; font-size: 12px; white-space: nowrap; }
+.b09ct__table th, .b09ct__table td { border: 1px solid var(--color-border); padding: 2px 6px; }
+.b09ct__table td.num { text-align: right; font-variant-numeric: tabular-nums; }
+.b09ct__table tr.is-group td { font-weight: 600; }
+.b09ct__table tr.is-excluded td { color: var(--color-text-secondary); }
+.b09ct__panel { display: flex; flex-direction: column; gap: 6px; font-size: 12px; }
+.b09ct__rates { display: flex; gap: 6px; align-items: center; flex-wrap: wrap; }
+.b09ct__rates input { width: 4.5em; text-align: right; }
+.b09ct__option { display: flex; gap: 4px; align-items: flex-start; }
+.b09ct__totals { font-size: 12px; font-variant-numeric: tabular-nums; }
+`;
+  document.head.append(style);
+}
+
+function el<K extends keyof HTMLElementTagNameMap>(
+  tag: K,
+  className = "",
+  text = "",
+): HTMLElementTagNameMap[K] {
+  const node = document.createElement(tag);
+  if (className) node.className = className;
+  if (text) node.textContent = text;
+  return node;
+}
+
+function won(value: string | null | undefined): string {
+  if (value === null || value === undefined || value === "") return "";
+  const n = Number(value);
+  return Number.isFinite(n) ? n.toLocaleString("ko-KR") : value;
+}
+
+/** 프로젝트별 입력 캐시 — [저장] 전 값(지침 5장 · 자동저장 없음). */
+const drafts = new Map<string, Record<string, string | boolean | string[]>>();
+
+async function fetchContract(projectId: string): Promise<ContractDto> {
+  const response = await fetch(
+    `${API_BASE_URL}/projects/${encodeURIComponent(projectId)}/estimation/contract`,
+    { credentials: "include" },
+  );
+  const body = (await response.json()) as ContractDto;
+  if (!response.ok) throw new Error(body.message ?? `HTTP ${response.status}`);
+  return body;
+}
+
+async function saveContract(
+  projectId: string,
+  values: Record<string, string | boolean | string[]>,
+): Promise<void> {
+  const response = await fetch(
+    `${API_BASE_URL}/projects/${encodeURIComponent(projectId)}/estimation/contract`,
+    {
+      method: "PUT",
+      credentials: "include",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify(values),
+    },
+  );
+  const body = (await response.json()) as { message?: string };
+  if (!response.ok) throw new Error(body.message ?? `HTTP ${response.status}`);
+}
+
+function drawPanel(ctx: B09TabContext, data: ContractDto, reload: () => void): void {
+  const projectId = ctx.projectId as string;
+  const draft = drafts.get(projectId) ?? { ...data.settings };
+  drafts.set(projectId, draft);
+  const box = el("div", "b09ct__panel");
+  box.append(el("strong", "", "단가 적용율"));
+  const rates = el("div", "b09ct__rates");
+  for (const field of data.fields.rates) {
+    const label = el("label", "b09ct__rates");
+    label.append(el("span", "", `【 ${field.label} 】`));
+    const input = el("input");
+    input.type = "number";
+    input.min = "0";
+    input.step = "0.001";
+    input.value = String(draft[field.key] ?? "100");
+    input.addEventListener("input", () => (draft[field.key] = input.value));
+    label.append(input, el("span", "", "%"));
+    rates.append(label);
+  }
+  box.append(rates);
+  for (const option of data.fields.options) {
+    const row = el("label", "b09ct__option");
+    const check = el("input");
+    check.type = "checkbox";
+    check.checked = Boolean(draft[option.key]);
+    check.addEventListener("change", () => (draft[option.key] = check.checked));
+    row.append(check, el("span", "", option.label));
+    box.append(row);
+    const unused = data.options_not_used[option.key];
+    if (unused) box.append(el("span", "b09ct__warn", `⚠ ${unused}`));
+  }
+  box.append(
+    createButton({
+      label: "저장",
+      onClick: async () => {
+        try {
+          await saveContract(projectId, draft);
+          drafts.delete(projectId);
+          showToast("계약 조건 저장 — 설계 내역은 그대로", "success");
+          reload();
+        } catch (error) {
+          showToast(error instanceof Error ? error.message : "저장 못 함", "error");
+        }
+      },
+    }),
+  );
+  const t = data.totals;
+  const totals = el("div", "b09ct__totals");
+  for (const [label, part] of [
+    ["재료비", "material"],
+    ["노무비", "labor"],
+    ["경비", "expense"],
+  ] as const) {
+    totals.append(
+      el(
+        "div",
+        "",
+        `${label} ${won(t.design[`${part}_krw`])} → ${won(t.contract[`${part}_krw`])}` +
+          (t.ratio_pct[part] ? ` (${t.ratio_pct[part]}%)` : ""),
+      ),
+    );
+  }
+  totals.append(
+    el("div", "", `직접공사비 ${won(t.design.total_krw)} → ${won(t.contract.total_krw)}`),
+  );
+  box.append(totals);
+  ctx.panel.append(box);
+}
+
+function drawBody(ctx: B09TabContext, data: ContractDto): void {
+  const projectId = ctx.projectId as string;
+  const draft = drafts.get(projectId) ?? { ...data.settings };
+  drafts.set(projectId, draft);
+  const excluded = new Set((draft.excluded as string[] | undefined) ?? []);
+  const wrap = el("div", "b09ct");
+  wrap.append(el("div", "b09ct__warn", `⚠ ${data.limit_note}`));
+  if (data.bill_missing_count) {
+    wrap.append(
+      el(
+        "div",
+        "b09ct__warn",
+        `⚠ 설계 내역 ${L("B09_Sheet_Missing")} ${data.bill_missing_count}${L("B09_Sheet_Count")} — 계약단가도 못 섬`,
+      ),
+    );
+  }
+  wrap.append(
+    el("div", "b09ct__meta", "적용율을 제외할(ex 관급자재대..) 공정을 선택 — [저장]하면 반영"),
+  );
+  const scroll = el("div", "b09ct__scroll");
+  const table = el("table", "b09ct__table");
+  const head = el("tr");
+  for (const label of [
+    "공종번호",
+    "명칭",
+    "규격",
+    "단위",
+    "수량",
+    "금액(설계)",
+    "계약 단가",
+    "계약 금액",
+    "적용제외",
+    "계약단가 코드",
+    "비고",
+  ]) {
+    head.append(el("th", "", label));
+  }
+  table.append(head);
+  for (const row of data.rows) {
+    const tr = el("tr", row.is_group ? "is-group" : row.contract_excluded ? "is-excluded" : "");
+    tr.append(
+      el("td", "", row.item_no),
+      el("td", "", row.name),
+      el("td", "", row.spec ?? ""),
+      el("td", "", row.unit ?? ""),
+      el("td", "num", row.quantity ?? ""),
+      el("td", "num", won(row.amount_krw)),
+      el("td", "num", won(row.contract_unit_price_krw)),
+      el("td", "num", won(row.contract_amount_krw)),
+    );
+    const cell = el("td");
+    if (!row.is_group && row.in_bill) {
+      const check = el("input");
+      check.type = "checkbox";
+      check.checked = excluded.has(row.item_no);
+      check.addEventListener("change", () => {
+        if (check.checked) excluded.add(row.item_no);
+        else excluded.delete(row.item_no);
+        draft.excluded = [...excluded];
+      });
+      cell.append(check);
+    }
+    tr.append(cell, el("td", "", row.contract_code ?? ""), el("td", "", row.contract_note ?? ""));
+    table.append(tr);
+  }
+  scroll.append(table);
+  wrap.append(scroll);
+  ctx.body.append(wrap);
+}
+
+function render(ctx: B09TabContext): void {
+  injectStyles();
+  if (!ctx.projectId) {
+    ctx.body.append(el("div", "b09ct__meta", "프로젝트를 고르세요"));
+    return;
+  }
+  const load = (): void => {
+    ctx.body.replaceChildren(el("div", "b09ct__meta", "계약내역 계산 중…"));
+    ctx.panel.replaceChildren();
+    fetchContract(ctx.projectId as string)
+      .then((data) => {
+        ctx.body.replaceChildren();
+        drawPanel(ctx, data, load);
+        drawBody(ctx, data);
+      })
+      .catch((error: unknown) => {
+        ctx.body.replaceChildren(
+          el(
+            "div",
+            "b09ct__warn",
+            `계약내역을 세우지 못함 — ${error instanceof Error ? error.message : ""}`,
+          ),
+        );
+      });
+  };
+  load();
+}
+
+export const contractTab: B09Tab = {
+  key: "contract",
+  label: () => L("B09_Estimation_Tab_Contract"),
+  render,
+};
diff --git a/main.py b/main.py
index 7d2edba6..b3cc9ca7 100644
--- a/main.py
+++ b/main.py
@@ -65,6 +65,7 @@ from B08_Quantity.B08_Quantity_Router_Earthwork import router as b08_earthwork_r
 from B08_Quantity.B08_Quantity_Router_Material import router as b08_material_router
 from B08_Quantity.B08_Quantity_Router_StructureSheet import router as b08_structure_sheet_router
 from B09_Estimation.B09_Estimation_Router import router as b09_estimation_router
+from B09_Estimation.B09_Estimation_Router_Contract import router as b09_contract_router
 from B09_Estimation.B09_Estimation_Router_CostSheet import router as b09_cost_sheet_router
 from B09_Estimation.B09_Estimation_Router_Edits import router as b09_edits_router
 from B09_Estimation.B09_Estimation_Router_Factors import router as b09_factors_router
@@ -640,6 +641,7 @@ app.include_router(b08_material_router, dependencies=protected_with_company)
 app.include_router(b08_structure_sheet_router, dependencies=protected_with_company)
 app.include_router(b09_estimation_router, dependencies=protected_with_company)
 app.include_router(b09_cost_sheet_router, dependencies=protected_with_company)
+app.include_router(b09_contract_router, dependencies=protected_with_company)
 app.include_router(b09_edits_router, dependencies=protected_with_company)
 app.include_router(b09_factors_router, dependencies=protected_with_company)
 # 개발 전용 잠금 해제 — 다른 라우터와 **같은 보호**를 받는다(로그인·회사·프로젝트 접근).
diff --git a/resources/tester/test_b09_contract.py b/resources/tester/test_b09_contract.py
new file mode 100644
index 00000000..3be35c0a
--- /dev/null
+++ b/resources/tester/test_b09_contract.py
@@ -0,0 +1,114 @@
+"""계약 단계 — 설계 → 계약내역 **구조**가 서는가 (PLAN 12장 · 2026-09-14 브레인 배정).
+
+⚠ 값이 맞는지는 못 잰다 — 계약 표본 0건(STmate 27번 §9). 여기서 재는 것:
+    ① 적용률 100% 면 설계와 같음 · 설계 줄(입력)은 안 바뀜
+    ② 노·재·경 따로 곱해짐 · 절사는 설계 내역 규칙(성분 단가 원 미만 · 줄 성분마다)
+    ③ 적용 제외 줄은 설계 단가 · W 코드 안 붙음
+    ④ 0% + 「공내역 생성」 = 0 원 공내역 줄 · 옵션 끄면 0% = 적용 안 함
+    ⑤ 동일코드 개별생성 켜면 줄마다 다른 W 코드 · 끄면 같은 코드 한 벌
+    ⑥ 묶음 줄 합 · 틀린 적용률 거름
+"""
+
+from __future__ import annotations
+
+import copy
+import sys
+from decimal import Decimal
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[2]
+sys.path.insert(0, str(ROOT))
+
+from B09_Estimation.B09_Estimation_Contract import clean_settings, contract_bill  # noqa: E402
+
+ROWS = [
+    {"item_no": "1", "is_group": True, "in_bill": True},
+    {
+        "item_no": "1.1",
+        "is_group": False,
+        "in_bill": True,
+        "quantity": "12.5",
+        "price_code": "B-FP-09-03-02",
+        "unit_material_krw": "1001",
+        "unit_labor_krw": "2003",
+        "unit_expense_krw": "3005",
+    },
+    {
+        "item_no": "1.2",
+        "is_group": False,
+        "in_bill": True,
+        "quantity": "3",
+        "price_code": "B-FP-09-03-02",
+        "unit_material_krw": "1001",
+        "unit_labor_krw": "2003",
+        "unit_expense_krw": "3005",
+    },
+    {
+        "item_no": "1.3",
+        "is_group": False,
+        "in_bill": True,
+        "quantity": "2",
+        "price_code": "M-관급자재",
+        "unit_material_krw": "50000",
+        "unit_labor_krw": "0",
+        "unit_expense_krw": "0",
+    },
+]
+
+
+def _rows(settings: dict) -> dict[str, dict]:
+    return {row["item_no"]: row for row in contract_bill(ROWS, settings)["rows"]}
+
+
+def test_100퍼센트면_설계와_같고_입력은_안_바뀐다() -> None:
+    before = copy.deepcopy(ROWS)
+    result = contract_bill(ROWS, clean_settings({})[0])
+    assert ROWS == before
+    assert result["totals"]["design"] == result["totals"]["contract"]
+
+
+def test_노재경을_따로_곱하고_성분_단가를_원_미만_절사() -> None:
+    row = _rows({"labor_pct": "80", "material_pct": "90", "expense_pct": "70"})["1.1"]
+    assert (
+        row["contract_unit_material_krw"],
+        row["contract_unit_labor_krw"],
+        row["contract_unit_expense_krw"],
+    ) == ("900", "1602", "2103")  # 900.9→900 · 1602.4→1602 · 2103.5→2103
+    assert row["contract_material_krw"] == "11250"  # 12.5 × 900
+    assert row["contract_code"] == "W-B-FP-09-03-02"
+
+
+def test_적용_제외_줄은_설계_단가_W코드_없음() -> None:
+    row = _rows({"material_pct": "50", "excluded": ["1.3"]})["1.3"]
+    assert row["contract_unit_material_krw"] == "50000" and row["contract_excluded"] is True
+    assert not row["contract_code"].startswith("W-")
+
+
+def test_0퍼센트_공내역_옵션() -> None:
+    zero = {"labor_pct": "0", "material_pct": "0", "expense_pct": "0"}
+    empty = _rows({**zero, "zero_makes_empty": True})["1.1"]
+    assert empty["contract_amount_krw"] == "0" and "공내역" in empty["contract_note"]
+    kept = _rows(zero)["1.1"]
+    assert kept["contract_unit_price_krw"] == "6009"  # 옵션 끄면 0% = 적용 안 함
+
+
+def test_동일코드_개별생성() -> None:
+    shared = _rows({"material_pct": "90"})
+    assert shared["1.1"]["contract_code"] == shared["1.2"]["contract_code"]
+    separate = _rows({"material_pct": "90", "separate_same_code": True})
+    assert separate["1.1"]["contract_code"] != separate["1.2"]["contract_code"]
+
+
+def test_묶음_줄_합과_합계_비율() -> None:
+    result = contract_bill(ROWS, {"material_pct": "90", "labor_pct": "90", "expense_pct": "90"})
+    group = result["rows"][0]
+    children = [r for r in result["rows"] if not r.get("is_group")]
+    assert Decimal(group["contract_amount_krw"]) == sum(
+        Decimal(r["contract_amount_krw"]) for r in children
+    )
+    assert result["totals"]["ratio_pct"]["labor"] is not None
+
+
+def test_틀린_적용률은_거른다() -> None:
+    cleaned, errors = clean_settings({"labor_pct": "-3", "material_pct": "abc", "expense_pct": ""})
+    assert len(errors) == 2 and cleaned["expense_pct"] == "100"
diff --git a/ui_template/ui_template_locale_b4.ts b/ui_template/ui_template_locale_b4.ts
index d0d3d7d6..70a5edf9 100644
--- a/ui_template/ui_template_locale_b4.ts
+++ b/ui_template/ui_template_locale_b4.ts
@@ -8,4 +8,5 @@
 
 export const ui_locales_b4 = {
   B09_Estimation_Tab_RateTable: ["제비율 요율표", "Overhead Rate Table"],
+  B09_Estimation_Tab_Contract: ["계약내역", "Contract Bill"],
 } as const;