diff --git a/frontend/package-lock.json b/frontend/package-lock.json
index 1995faa9..7acfd81f 100644
--- a/frontend/package-lock.json
+++ b/frontend/package-lock.json
@@ -7262,9 +7262,9 @@
       }
     },
     "node_modules/shell-quote": {
-      "version": "1.8.3",
-      "resolved": "https://registry.npmjs.org/shell-quote/-/shell-quote-1.8.3.tgz",
-      "integrity": "sha512-ObmnIF4hXNg1BqhnHmgbDETF8dLPCggZWBjkQfhZpbszZnYur5DUljTcCHii5LC3J5E0yeO/1LIMyH+UvHQgyw==",
+      "version": "1.8.4",
+      "resolved": "https://registry.npmjs.org/shell-quote/-/shell-quote-1.8.4.tgz",
+      "integrity": "sha512-VsC6n6vz1ihYYyZZwX7YZSF5l5x36ca17OC+a69h94YqB7X6XLwf+5MOgynYir2SLFUbl8gIYvBo8K8RoNQ6bQ==",
       "dev": true,
       "license": "MIT",
       "engines": {
diff --git a/frontend/package.json b/frontend/package.json
index 1eb1842e..c03a4f88 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -59,5 +59,8 @@
     "vite": "^6.0.5",
     "vitest": "^4.1.2",
     "wrangler": "^4.90.0"
+  },
+  "overrides": {
+    "shell-quote": "^1.8.4"
   }
 }
diff --git a/frontend/src/components/ConfirmDialog.tsx b/frontend/src/components/ConfirmDialog.tsx
index 32fcc9ab..5b90c1ca 100644
--- a/frontend/src/components/ConfirmDialog.tsx
+++ b/frontend/src/components/ConfirmDialog.tsx
@@ -1,3 +1,4 @@
+import { UI_MESSAGES } from "../constants/messages";
 import styles from "./ConfirmDialog.module.css";
 
 export function ConfirmDialog({
@@ -21,10 +22,10 @@ export function ConfirmDialog({
         <p className={styles.message}>{message}</p>
         <div className={styles.actions}>
           <button type="button" className="danger" onClick={onConfirm} disabled={confirming}>
-            {confirming ? (confirmingLabel ?? "削除中...") : confirmLabel}
+            {confirming ? (confirmingLabel ?? UI_MESSAGES.CONFIRM_DELETING) : confirmLabel}
           </button>
           <button type="button" onClick={onCancel} disabled={confirming}>
-            キャンセル
+            {UI_MESSAGES.CONFIRM_CANCEL}
           </button>
         </div>
       </div>
diff --git a/frontend/src/components/forms/CareerFormEditors/CareerExperienceEditor.tsx b/frontend/src/components/forms/CareerFormEditors/CareerExperienceEditor.tsx
index 7171c8db..ac198a74 100644
--- a/frontend/src/components/forms/CareerFormEditors/CareerExperienceEditor.tsx
+++ b/frontend/src/components/forms/CareerFormEditors/CareerExperienceEditor.tsx
@@ -1,5 +1,5 @@
 import { CAPITAL_UNITS } from "../../../constants";
-import type { CareerClientFieldKey, CareerExperienceFieldKey } from "../../../formTypes";
+import type { CareerExperienceFieldKey, ClientMutationHandlers } from "../../../formTypes";
 import type { ExperienceDirty } from "../../../hooks/career/useCareerDirty";
 import { useFocusOnMatch } from "../../../hooks/useFocusOnMatch";
 import {
@@ -17,8 +17,12 @@ import { DirtyDot } from "../../ui/DirtyDot";
 import { PlusIcon } from "../../icons/PlusIcon";
 import { ClientEditor } from "./ClientEditor";
 
-/** CareerExperienceEditor のプロパティ型 */
-type CareerExperienceEditorProps = {
+/**
+ * CareerExperienceEditor のプロパティ型。
+ * 取引先（client）配下のハンドラ群は ClientEditor へ素通しするため
+ * ClientMutationHandlers で ClientEditor と共有する。
+ */
+type CareerExperienceEditorProps = ClientMutationHandlers & {
   /** 編集対象の職務経歴データ */
   exp: CareerExperienceForm;
   /** この職務経歴のインデックス */
@@ -29,27 +33,8 @@ type CareerExperienceEditorProps = {
     key: CareerExperienceFieldKey,
     value: string | boolean,
   ) => void;
-  /** 取引先フィールド変更ハンドラ */
-  onUpdateClientField: (
-    expIndex: number,
-    clientIndex: number,
-    key: CareerClientFieldKey,
-    value: string,
-  ) => void;
-  /** 取引先「取引先なし」切替ハンドラ */
-  onUpdateClientHasClient: (expIndex: number, clientIndex: number, value: boolean) => void;
-  /** 取引先「休暇」切替ハンドラ */
-  onUpdateClientIsVacation: (expIndex: number, clientIndex: number, value: boolean) => void;
-  /** 休暇「継続中」切替ハンドラ */
-  onUpdateClientVacationIsCurrent: (expIndex: number, clientIndex: number, value: boolean) => void;
   /** 取引先追加ハンドラ */
   onAddClient: (expIndex: number) => void;
-  /** 取引先削除ハンドラ */
-  onRemoveClient: (expIndex: number, clientIndex: number) => void;
-  /** プロジェクト削除ハンドラ */
-  onRemoveProject: (expIndex: number, clientIndex: number, projIndex: number) => void;
-  /** プロジェクト編集モーダルを開くハンドラ */
-  onOpenProjectModal: (expIndex: number, clientIndex: number, projIndex: number | null) => void;
   /** 職務経歴削除ハンドラ */
   onRemoveExperience: (index: number) => void;
   /** プロジェクトサマリーテキストを生成する関数 */
diff --git a/frontend/src/components/forms/CareerFormEditors/ClientEditor.tsx b/frontend/src/components/forms/CareerFormEditors/ClientEditor.tsx
index 4e54f0c4..f0a147e9 100644
--- a/frontend/src/components/forms/CareerFormEditors/ClientEditor.tsx
+++ b/frontend/src/components/forms/CareerFormEditors/ClientEditor.tsx
@@ -1,4 +1,4 @@
-import type { CareerClientFieldKey } from "../../../formTypes";
+import type { ClientMutationHandlers } from "../../../formTypes";
 import type { ClientDirty } from "../../../hooks/career/useCareerDirty";
 import { useFocusOnMatch } from "../../../hooks/useFocusOnMatch";
 import {
@@ -14,8 +14,8 @@ import { DeleteIconButton } from "../../ui/DeleteIconButton";
 import { DirtyDot } from "../../ui/DirtyDot";
 import { PlusIcon } from "../../icons/PlusIcon";
 
-/** ClientEditor のプロパティ型 */
-type ClientEditorProps = {
+/** ClientEditor のプロパティ型（取引先配下のハンドラ群は ClientMutationHandlers で共有） */
+type ClientEditorProps = ClientMutationHandlers & {
   /** 編集対象の取引先データ */
   client: CareerClientForm;
   /** 親となる職務経歴のインデックス */
@@ -24,25 +24,6 @@ type ClientEditorProps = {
   clientIndex: number;
   /** この取引先の dirty 情報。未指定なら 🔴 表示なし。 */
   dirty?: ClientDirty;
-  /** 取引先フィールド変更ハンドラ */
-  onUpdateClientField: (
-    expIndex: number,
-    clientIndex: number,
-    key: CareerClientFieldKey,
-    value: string,
-  ) => void;
-  /** 取引先「取引先なし」切替ハンドラ */
-  onUpdateClientHasClient: (expIndex: number, clientIndex: number, value: boolean) => void;
-  /** 取引先「休暇」切替ハンドラ */
-  onUpdateClientIsVacation: (expIndex: number, clientIndex: number, value: boolean) => void;
-  /** 休暇「継続中」切替ハンドラ */
-  onUpdateClientVacationIsCurrent: (expIndex: number, clientIndex: number, value: boolean) => void;
-  /** プロジェクト削除ハンドラ */
-  onRemoveProject: (expIndex: number, clientIndex: number, projIndex: number) => void;
-  /** プロジェクト編集モーダルを開くハンドラ */
-  onOpenProjectModal: (expIndex: number, clientIndex: number, projIndex: number | null) => void;
-  /** 取引先削除ハンドラ */
-  onRemoveClient: (expIndex: number, clientIndex: number) => void;
   /** プロジェクトサマリーテキストを生成する関数 */
   projectSummary: (proj: CareerProjectForm) => string;
   /** バリデーション失敗フィールドの位置情報（休暇期間のフォーカス・赤枠用） */
diff --git a/frontend/src/components/forms/CareerResumeForm.test.tsx b/frontend/src/components/forms/CareerResumeForm.test.tsx
new file mode 100644
index 00000000..8d5f0f18
--- /dev/null
+++ b/frontend/src/components/forms/CareerResumeForm.test.tsx
@@ -0,0 +1,78 @@
+import { fireEvent, render, screen, waitFor } from "@testing-library/react";
+import { Provider } from "react-redux";
+import { configureStore } from "@reduxjs/toolkit";
+import { describe, it, expect, vi, beforeEach } from "vitest";
+
+import { CareerResumeForm } from "./CareerResumeForm";
+import { LoginPromptContext } from "../auth/loginPromptContext";
+import { ToastProvider } from "../ui/toast";
+import formCacheReducer from "../../store/formCacheSlice";
+import { UI_MESSAGES, VALIDATION_MESSAGES } from "../../constants/messages";
+
+// 原本ビューは react-pdf / pdf.js を遅延ロードするため、フォームの単体テストではスタブに差し替える。
+vi.mock("./ResumeSourceTracePanel", () => ({
+  ResumeSourceTracePanel: () => <div data-testid="source-panel-stub" />,
+}));
+
+// マスタデータ取得は実 fetch を避けて空配列を返す（匿名分岐の検証には不要なため）。
+vi.mock("../../api/master-data", () => ({
+  getQualifications: vi.fn().mockResolvedValue([]),
+  getTechnologyStacks: vi.fn().mockResolvedValue([]),
+}));
+
+/** formCache だけを持つ最小ストアを作る。 */
+function makeStore() {
+  return configureStore({ reducer: { formCache: formCacheReducer } });
+}
+
+/** 未ログイン状態の CareerResumeForm を描画し、requestLogin スパイを返す。 */
+function renderAnonymousForm() {
+  const requestLogin = vi.fn();
+  render(
+    <Provider store={makeStore()}>
+      <LoginPromptContext.Provider value={requestLogin}>
+        <ToastProvider>
+          <CareerResumeForm isAuthenticated={false} />
+        </ToastProvider>
+      </LoginPromptContext.Provider>
+    </Provider>,
+  );
+  return { requestLogin };
+}
+
+describe("CareerResumeForm（未ログインの保存導線）", () => {
+  beforeEach(() => {
+    // ドラフト退避（sessionStorage）がテスト間で漏れないようにする。
+    window.sessionStorage.clear();
+  });
+
+  /** 保存ボタンはマスタデータ取得が終わるまで非活性なので、活性化を待ってから返す。 */
+  async function waitForEnabledSaveButton(): Promise<HTMLElement> {
+    const button = screen.getByRole("button", { name: UI_MESSAGES.FORM_SAVE });
+    await waitFor(() => expect(button).toBeEnabled());
+    return button;
+  }
+
+  it("氏名が空のまま保存すると、ログインを促さず氏名必須エラーを表示する", async () => {
+    const { requestLogin } = renderAnonymousForm();
+
+    fireEvent.click(await waitForEnabledSaveButton());
+
+    expect(screen.getByText(VALIDATION_MESSAGES.FULL_NAME_REQUIRED)).toBeInTheDocument();
+    expect(requestLogin).not.toHaveBeenCalled();
+  });
+
+  it("氏名を入力して保存すると、バリデーションを通してログイン促進を呼ぶ", async () => {
+    const { requestLogin } = renderAnonymousForm();
+
+    const saveButton = await waitForEnabledSaveButton();
+    // 氏名入力はプレースホルダ文言ではなくラベル（ロール + アクセシブル名）で特定する。
+    fireEvent.change(screen.getByRole("textbox", { name: /氏名/ }), {
+      target: { value: "山田 太郎" },
+    });
+    fireEvent.click(saveButton);
+
+    expect(requestLogin).toHaveBeenCalledTimes(1);
+    expect(screen.queryByText(VALIDATION_MESSAGES.FULL_NAME_REQUIRED)).not.toBeInTheDocument();
+  });
+});
diff --git a/frontend/src/components/forms/CareerResumeForm.tsx b/frontend/src/components/forms/CareerResumeForm.tsx
index 8d109f31..d930b1ac 100644
--- a/frontend/src/components/forms/CareerResumeForm.tsx
+++ b/frontend/src/components/forms/CareerResumeForm.tsx
@@ -298,8 +298,8 @@ export function CareerResumeForm({ isAuthenticated }: { isAuthenticated: boolean
     <>
       {showDeleteConfirm && (
         <ConfirmDialog
-          message="職務経歴書のデータを全て削除します。この操作は取り消せません。本当に削除しますか？"
-          confirmLabel="削除する"
+          message={UI_MESSAGES.RESUME_DELETE_CONFIRM}
+          confirmLabel={UI_MESSAGES.RESUME_DELETE_CONFIRM_LABEL}
           onConfirm={handleDelete}
           onCancel={() => setShowDeleteConfirm(false)}
           confirming={deleting}
diff --git a/frontend/src/constants/messages.ts b/frontend/src/constants/messages.ts
index 14ff1b87..a5d277cc 100644
--- a/frontend/src/constants/messages.ts
+++ b/frontend/src/constants/messages.ts
@@ -156,6 +156,17 @@ export const UI_MESSAGES = {
   RESUME_DELETE_VACATION: "休業を削除",
   RESUME_DELETE_PROJECT: "プロジェクトを削除",
   RESUME_DELETE_QUALIFICATION: "資格を削除",
+  // 職務経歴書「データを削除」確認ダイアログ（ConfirmDialog の message / confirmLabel）
+  RESUME_DELETE_CONFIRM:
+    "職務経歴書のデータを全て削除します。この操作は取り消せません。本当に削除しますか？",
+  RESUME_DELETE_CONFIRM_LABEL: "削除する",
+  // 確認ダイアログ共通（ConfirmDialog のボタン文言）
+  CONFIRM_DELETING: "削除中...",
+  CONFIRM_CANCEL: "キャンセル",
+  // ドキュメントフォームの保存ボタン文言（useDocumentForm の saveButtonText）
+  FORM_SAVING: "保存中...",
+  FORM_UPDATE: "更新する",
+  FORM_SAVE: "保存する",
 } as const;
 
 /** 外部リンク URL（GitHub リポジトリ / Issue 報告先など）の SSoT */
diff --git a/frontend/src/formTypes.ts b/frontend/src/formTypes.ts
index 945531dd..611a78ed 100644
--- a/frontend/src/formTypes.ts
+++ b/frontend/src/formTypes.ts
@@ -17,3 +17,30 @@ export type CareerClientFieldKey =
   | "vacation_description";
 export type CareerProjectFieldKey = "name" | "role" | "description";
 export type CareerProjectPeriodFieldKey = "start_date" | "end_date" | "is_current";
+
+/**
+ * 取引先（client）配下のミューテーションハンドラ群。
+ * CareerExperienceEditor が ClientEditor へ素通しするため、両 Props 型で共有する
+ * （片方だけ引数を足したときの取り違えを型で防ぐ）。
+ */
+export type ClientMutationHandlers = {
+  /** 取引先フィールド変更ハンドラ */
+  onUpdateClientField: (
+    expIndex: number,
+    clientIndex: number,
+    key: CareerClientFieldKey,
+    value: string,
+  ) => void;
+  /** 取引先「取引先なし」切替ハンドラ */
+  onUpdateClientHasClient: (expIndex: number, clientIndex: number, value: boolean) => void;
+  /** 取引先「休暇」切替ハンドラ */
+  onUpdateClientIsVacation: (expIndex: number, clientIndex: number, value: boolean) => void;
+  /** 休暇「継続中」切替ハンドラ */
+  onUpdateClientVacationIsCurrent: (expIndex: number, clientIndex: number, value: boolean) => void;
+  /** プロジェクト削除ハンドラ */
+  onRemoveProject: (expIndex: number, clientIndex: number, projIndex: number) => void;
+  /** プロジェクト編集モーダルを開くハンドラ */
+  onOpenProjectModal: (expIndex: number, clientIndex: number, projIndex: number | null) => void;
+  /** 取引先削除ハンドラ */
+  onRemoveClient: (expIndex: number, clientIndex: number) => void;
+};
diff --git a/frontend/src/hooks/career/useCareerExperienceMutators.ts b/frontend/src/hooks/career/useCareerExperienceMutators.ts
index b88e47d0..d6b668d3 100644
--- a/frontend/src/hooks/career/useCareerExperienceMutators.ts
+++ b/frontend/src/hooks/career/useCareerExperienceMutators.ts
@@ -10,6 +10,7 @@ import type {
   CareerExperienceFieldKey,
 } from "../../formTypes";
 import type {
+  CareerClientForm,
   CareerExperienceForm,
   CareerFormState,
   CareerProjectForm,
@@ -24,23 +25,48 @@ export function useCareerExperienceMutators(
   experiences: CareerExperienceForm[],
   setForm: Dispatch<SetStateAction<CareerFormState>>,
 ) {
+  /**
+   * 指定 index の experience を updater で書き換える共通ヘルパ。
+   * 三階層 immutable 更新の「該当 1 件だけ map で差し替える」定型をここに集約する。
+   */
+  const updateExperienceAt = (
+    expIndex: number,
+    updater: (exp: CareerExperienceForm) => CareerExperienceForm,
+  ) => {
+    setForm((prev) => ({
+      ...prev,
+      experiences: prev.experiences.map((exp, ei) => (ei === expIndex ? updater(exp) : exp)),
+    }));
+  };
+
+  /**
+   * 指定座標（experience → client）の client を updater で書き換える共通ヘルパ。
+   * updateExperienceAt の上に client 1 件差し替えを重ねる。
+   */
+  const updateClientAt = (
+    expIndex: number,
+    clientIndex: number,
+    updater: (client: CareerClientForm) => CareerClientForm,
+  ) => {
+    updateExperienceAt(expIndex, (exp) => ({
+      ...exp,
+      clients: exp.clients.map((c, ci) => (ci === clientIndex ? updater(c) : c)),
+    }));
+  };
+
   /** experience フィールド変更ハンドラ */
   const updateExperienceField = (
     index: number,
     key: CareerExperienceFieldKey,
     value: string | boolean,
   ) => {
-    setForm((prev) => ({
-      ...prev,
-      experiences: prev.experiences.map((exp, i) => {
-        if (i !== index) return exp;
-        if (key === "is_current") {
-          const isCurrent = Boolean(value);
-          return { ...exp, is_current: isCurrent, end_date: isCurrent ? "" : exp.end_date };
-        }
-        return { ...exp, [key]: value };
-      }),
-    }));
+    updateExperienceAt(index, (exp) => {
+      if (key === "is_current") {
+        const isCurrent = Boolean(value);
+        return { ...exp, is_current: isCurrent, end_date: isCurrent ? "" : exp.end_date };
+      }
+      return { ...exp, [key]: value };
+    });
   };
 
   /** client フィールド変更ハンドラ */
@@ -50,50 +76,21 @@ export function useCareerExperienceMutators(
     key: CareerClientFieldKey,
     value: string,
   ) => {
-    setForm((prev) => ({
-      ...prev,
-      experiences: prev.experiences.map((exp, ei) => {
-        if (ei !== expIndex) return exp;
-        return {
-          ...exp,
-          clients: exp.clients.map((c, ci) =>
-            ci === clientIndex ? { ...c, [key]: value } : c,
-          ),
-        };
-      }),
-    }));
+    updateClientAt(expIndex, clientIndex, (c) => ({ ...c, [key]: value }));
   };
 
   /** 「取引先なし」フラグ切り替えハンドラ */
   const updateClientHasClient = (expIndex: number, clientIndex: number, value: boolean) => {
-    setForm((prev) => ({
-      ...prev,
-      experiences: prev.experiences.map((exp, ei) => {
-        if (ei !== expIndex) return exp;
-        return {
-          ...exp,
-          clients: exp.clients.map((c, ci) =>
-            ci === clientIndex ? { ...c, has_client: value, name: value ? c.name : "" } : c,
-          ),
-        };
-      }),
+    updateClientAt(expIndex, clientIndex, (c) => ({
+      ...c,
+      has_client: value,
+      name: value ? c.name : "",
     }));
   };
 
   /** 「休暇」フラグ切り替えハンドラ */
   const updateClientIsVacation = (expIndex: number, clientIndex: number, value: boolean) => {
-    setForm((prev) => ({
-      ...prev,
-      experiences: prev.experiences.map((exp, ei) => {
-        if (ei !== expIndex) return exp;
-        return {
-          ...exp,
-          clients: exp.clients.map((c, ci) =>
-            ci === clientIndex ? { ...c, is_vacation: value } : c,
-          ),
-        };
-      }),
-    }));
+    updateClientAt(expIndex, clientIndex, (c) => ({ ...c, is_vacation: value }));
   };
 
   /** 休暇の「継続中」フラグ切り替えハンドラ（継続中なら終了年月をクリア） */
@@ -102,75 +99,40 @@ export function useCareerExperienceMutators(
     clientIndex: number,
     value: boolean,
   ) => {
-    setForm((prev) => ({
-      ...prev,
-      experiences: prev.experiences.map((exp, ei) => {
-        if (ei !== expIndex) return exp;
-        return {
-          ...exp,
-          clients: exp.clients.map((c, ci) =>
-            ci === clientIndex
-              ? {
-                ...c,
-                vacation_is_current: value,
-                vacation_end_date: value ? "" : c.vacation_end_date,
-              }
-              : c,
-          ),
-        };
-      }),
+    updateClientAt(expIndex, clientIndex, (c) => ({
+      ...c,
+      vacation_is_current: value,
+      vacation_end_date: value ? "" : c.vacation_end_date,
     }));
   };
 
   /** 取引先追加ハンドラ */
   const addClient = (expIndex: number) => {
-    setForm((prev) => ({
-      ...prev,
-      experiences: prev.experiences.map((exp, ei) =>
-        ei === expIndex
-          ? { ...exp, clients: [...exp.clients, { ...blankCareerClient }] }
-          : exp,
-      ),
+    updateExperienceAt(expIndex, (exp) => ({
+      ...exp,
+      clients: [...exp.clients, { ...blankCareerClient }],
     }));
   };
 
-  /** 取引先削除ハンドラ */
+  /** 取引先削除ハンドラ（最後の 1 件は空レコードへリセット） */
   const removeClient = (expIndex: number, clientIndex: number) => {
-    setForm((prev) => ({
-      ...prev,
-      experiences: prev.experiences.map((exp, ei) => {
-        if (ei !== expIndex) return exp;
-        return {
-          ...exp,
-          clients:
-            exp.clients.length === 1
-              ? [{ ...blankCareerClient }]
-              : exp.clients.filter((_, ci) => ci !== clientIndex),
-        };
-      }),
+    updateExperienceAt(expIndex, (exp) => ({
+      ...exp,
+      clients:
+        exp.clients.length === 1
+          ? [{ ...blankCareerClient }]
+          : exp.clients.filter((_, ci) => ci !== clientIndex),
     }));
   };
 
-  /** プロジェクト削除ハンドラ */
+  /** プロジェクト削除ハンドラ（最後の 1 件は空レコードへリセット） */
   const removeProject = (expIndex: number, clientIndex: number, projIndex: number) => {
-    setForm((prev) => ({
-      ...prev,
-      experiences: prev.experiences.map((exp, ei) => {
-        if (ei !== expIndex) return exp;
-        return {
-          ...exp,
-          clients: exp.clients.map((c, ci) => {
-            if (ci !== clientIndex) return c;
-            return {
-              ...c,
-              projects:
-                c.projects.length === 1
-                  ? [{ ...blankCareerProject }]
-                  : c.projects.filter((_, pi) => pi !== projIndex),
-            };
-          }),
-        };
-      }),
+    updateClientAt(expIndex, clientIndex, (c) => ({
+      ...c,
+      projects:
+        c.projects.length === 1
+          ? [{ ...blankCareerProject }]
+          : c.projects.filter((_, pi) => pi !== projIndex),
     }));
   };
 
@@ -223,25 +185,11 @@ export function useCareerExperienceMutators(
     projIndex: number | null,
     project: CareerProjectForm,
   ) => {
-    setForm((prev) => ({
-      ...prev,
-      experiences: prev.experiences.map((exp, ei) => {
-        if (ei !== expIndex) return exp;
-        return {
-          ...exp,
-          clients: exp.clients.map((c, ci) => {
-            if (ci !== clientIndex) return c;
-            if (projIndex === null) {
-              return { ...c, projects: [...c.projects, project] };
-            }
-            return {
-              ...c,
-              projects: c.projects.map((p, pi) => (pi === projIndex ? project : p)),
-            };
-          }),
-        };
-      }),
-    }));
+    updateClientAt(expIndex, clientIndex, (c) =>
+      projIndex === null
+        ? { ...c, projects: [...c.projects, project] }
+        : { ...c, projects: c.projects.map((p, pi) => (pi === projIndex ? project : p)) },
+    );
   };
 
   return {
diff --git a/frontend/src/hooks/useDocumentForm.ts b/frontend/src/hooks/useDocumentForm.ts
index 5e68f9e6..03c52a44 100644
--- a/frontend/src/hooks/useDocumentForm.ts
+++ b/frontend/src/hooks/useDocumentForm.ts
@@ -1,7 +1,7 @@
 import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import type { Dispatch, SetStateAction } from "react";
 
-import { FALLBACK_MESSAGES } from "../constants/messages";
+import { FALLBACK_MESSAGES, UI_MESSAGES } from "../constants/messages";
 import { useAppDispatch, useAppSelector } from "../store";
 import {
   clearCache,
@@ -172,8 +172,8 @@ export function useDocumentForm<FormState, Payload, Response extends { id: strin
   }, [loadLatest, mapResponseToForm, updateCache, commitBaseline, skipLoad]);
 
   const saveButtonText = useMemo(() => {
-    if (saving) return "保存中...";
-    return documentId ? "更新する" : "保存する";
+    if (saving) return UI_MESSAGES.FORM_SAVING;
+    return documentId ? UI_MESSAGES.FORM_UPDATE : UI_MESSAGES.FORM_SAVE;
   }, [documentId, saving]);
 
   /**