From 85c50fad39c2014a0ac478624535ff18bc4ae84e Mon Sep 17 00:00:00 2001
From: Matthew Laszcz <mlaszcz@cryptolab.co.kr>
Date: Fri, 24 Jul 2026 08:22:52 +0900
Subject: [PATCH 1/4] =?UTF-8?q?feat(frontend):=20bilingual=20UI=20?=
 =?UTF-8?q?=E2=80=94=20static=20en/ko=20locales=20with=20language=20toggle?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Move every user-visible Korean string into src/locales (ko.ts verbatim,
en.ts translated). The locale is chosen once at page load (localStorage
rc_lang override, else browser language) and exported as L; components
read plain constants — no i18n library, no runtime lookup. ko.ts is
typed against en.ts's shape so the two languages cannot drift apart
silently. Parameterized strings are per-language functions so Korean
counters and English word order each read naturally.

A globe LanguageToggle (labeled with the language it switches to) sits
in both navbars — signed-in and signed-out — and persists + reloads.

Tests are pinned to Korean in setup.ts since the suite asserts the
original copy; locales.test.ts covers the English side and structural
parity. Dev-only fixtures (UITestPage, teamsDummyData) and code
comments intentionally keep their Korean.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .../src/components/auth/OwnerLockedNotice.tsx |  11 +-
 .../src/components/drawer/MembershipRow.tsx   |   5 +-
 frontend/src/components/elements/Dropdown.tsx |   3 +-
 .../src/components/elements/Pagination.tsx    |   7 +-
 .../src/components/elements/SearchInput.tsx   |   5 +-
 .../components/navigation/LanguageToggle.tsx  |  28 ++
 frontend/src/components/navigation/Navbar.tsx |  13 +-
 .../src/components/navigation/ProfileMenu.tsx |   7 +-
 .../components/navigation/PublicNavbar.tsx    |  22 +-
 .../src/components/teams/AddMemberModal.tsx   |  17 +-
 .../src/components/teams/CreateTeamModal.tsx  |  15 +-
 .../src/components/teams/DeleteTeamModal.tsx  |  33 +-
 frontend/src/components/teams/OrgChart.tsx    |   7 +-
 .../teams/RemoveMembershipModal.tsx           |  13 +-
 .../src/components/teams/RenameTeamModal.tsx  |   5 +-
 .../teams/RoleChangeConfirmModal.tsx          |   7 +-
 .../src/components/teams/TreeDetailView.tsx   | 122 +++---
 frontend/src/components/teams/teamOptions.ts  |   4 +-
 .../src/components/toast/ToastContainer.tsx   |   3 +-
 frontend/src/components/tree/TeamTree.tsx     |   5 +-
 frontend/src/components/tree/TreeNode.tsx     |   7 +-
 .../components/update/UpdateFloatingCard.tsx  |  19 +-
 .../users/CancelInvitationModal.tsx           |   5 +-
 .../components/users/InviteMemberModal.tsx    |  36 +-
 .../components/users/MemberDeleteModal.tsx    |  13 +-
 .../components/users/MemberDetailDrawer.tsx   |  83 ++--
 .../users/MembershipRemoveModal.tsx           |  11 +-
 .../users/RoleChangeConfirmModal.tsx          |   9 +-
 .../users/SessionDeactivateModal.tsx          |   5 +-
 .../src/components/users/invitePreview.ts     |   7 +-
 .../components/workspace/WorkspaceModal.tsx   |  44 +-
 frontend/src/constants/commonConstants.ts     |  92 +----
 frontend/src/constants/styleConstants.ts      |  31 +-
 .../src/locales/__tests__/locales.test.ts     |  49 +++
 frontend/src/locales/en.ts                    | 386 ++++++++++++++++++
 frontend/src/locales/index.ts                 |  37 ++
 frontend/src/locales/ko.ts                    | 373 +++++++++++++++++
 frontend/src/pages/LoginPage.tsx              |   7 +-
 frontend/src/pages/SessionsPage.tsx           |  35 +-
 frontend/src/pages/TeamsPage.tsx              |  35 +-
 frontend/src/pages/UsersPage.tsx              |  80 ++--
 frontend/src/pages/WorkspacePage.tsx          |  21 +-
 frontend/src/test/setup.ts                    |   6 +
 frontend/src/utils/username.ts                |   5 +-
 44 files changed, 1312 insertions(+), 416 deletions(-)
 create mode 100644 frontend/src/components/navigation/LanguageToggle.tsx
 create mode 100644 frontend/src/locales/__tests__/locales.test.ts
 create mode 100644 frontend/src/locales/en.ts
 create mode 100644 frontend/src/locales/index.ts
 create mode 100644 frontend/src/locales/ko.ts

diff --git a/frontend/src/components/auth/OwnerLockedNotice.tsx b/frontend/src/components/auth/OwnerLockedNotice.tsx
index aa14caa..8259ce2 100644
--- a/frontend/src/components/auth/OwnerLockedNotice.tsx
+++ b/frontend/src/components/auth/OwnerLockedNotice.tsx
@@ -6,6 +6,7 @@ import RuneMark from "@/components/elements/RuneMark";
 import PublicNavbar from "@/components/navigation/PublicNavbar";
 import { postLogout } from "@/api/authAPIs";
 import { BTN_TEXT, PATH_LIST, QUERY_KEYS } from "@/constants/commonConstants";
+import { L } from "@/locales";
 
 /**
  * OwnerLockedNotice is the soft-block screen shown when a signed-in account is
@@ -35,18 +36,18 @@ const OwnerLockedNotice = ({ owner }: { owner?: string }) => {
         <div className="border-border bg-panel-solid flex w-100 flex-col gap-8 rounded-lg border p-7 text-center">
           <div className="flex items-center justify-center gap-2">
             <RuneMark />
-            <h1 className="text-lg font-semibold">사용할 수 없는 계정</h1>
+            <h1 className="text-lg font-semibold">{L.auth.ownerLockedTitle}</h1>
           </div>
           <p className="text-muted-foreground text-md">
-            이 콘솔은{" "}
+            {L.auth.ownerLockedPrefix}
             {owner ? (
               <span className="text-foreground font-medium">{owner}</span>
             ) : (
-              "다른 계정"
+              L.auth.ownerFallback
             )}
-            이(가) 관리하고 있어요.
+            {L.auth.ownerLockedSuffix}
             <br />
-            이 계정으로는 콘솔을 사용할 수 없습니다.
+            {L.auth.ownerLockedBody}
           </p>
           <Button
             btnText={BTN_TEXT.signOut}
diff --git a/frontend/src/components/drawer/MembershipRow.tsx b/frontend/src/components/drawer/MembershipRow.tsx
index 850fea0..0c49008 100644
--- a/frontend/src/components/drawer/MembershipRow.tsx
+++ b/frontend/src/components/drawer/MembershipRow.tsx
@@ -3,6 +3,7 @@ import Dropdown from "@/components/elements/Dropdown";
 import TableCell from "@/components/table/TableCell";
 import TableRow from "@/components/table/TableRow";
 import { cn } from "@/utils/cn";
+import { L } from "@/locales";
 import type { TDropdownOption } from "@/types/commonTypes";
 
 const styles = {
@@ -46,7 +47,7 @@ const MembershipRow = ({
         <Checkbox
           checked={checked}
           onChange={onCheck}
-          ariaLabel={`${name} 선택`}
+          ariaLabel={L.common.selectName(name)}
         />
       </TableCell>
       <TableCell>
@@ -56,7 +57,7 @@ const MembershipRow = ({
         >
           {name}
           {changed && (
-            <em className={styles.changedBadge} aria-label="변경사항 있음">
+            <em className={styles.changedBadge} aria-label={L.elements.unsavedChanges}>
               CHANGED
             </em>
           )}
diff --git a/frontend/src/components/elements/Dropdown.tsx b/frontend/src/components/elements/Dropdown.tsx
index cf06022..dc41583 100644
--- a/frontend/src/components/elements/Dropdown.tsx
+++ b/frontend/src/components/elements/Dropdown.tsx
@@ -4,6 +4,7 @@ import { createPortal } from "react-dom";
 import { ChevronDown } from "lucide-react";
 
 import { cn } from "@/utils/cn";
+import { L } from "@/locales";
 import type { TDropdownOption } from "@/types/commonTypes";
 
 const styles = {
@@ -91,7 +92,7 @@ interface DropdownProps {
 const Dropdown = ({
   options,
   label,
-  placeholder = "선택",
+  placeholder = L.common.select,
   hint,
   error,
   value,
diff --git a/frontend/src/components/elements/Pagination.tsx b/frontend/src/components/elements/Pagination.tsx
index 2195a30..a91998e 100644
--- a/frontend/src/components/elements/Pagination.tsx
+++ b/frontend/src/components/elements/Pagination.tsx
@@ -1,4 +1,5 @@
 import { cn } from "@/utils/cn";
+import { L } from "@/locales";
 
 const styles = {
   wrap: "flex w-fit items-center gap-2 font-mono text-sm",
@@ -29,11 +30,11 @@ const Pagination = ({
   className,
 }: PaginationProps) => {
   return (
-    <nav className={cn(styles.wrap, className)} aria-label="페이지네이션">
+    <nav className={cn(styles.wrap, className)} aria-label={L.elements.pagination}>
       <button
         type="button"
         className={styles.arrow}
-        aria-label="이전 페이지"
+        aria-label={L.elements.prevPage}
         disabled={page <= 1}
         onClick={() => onChange(page - 1)}
       >
@@ -53,7 +54,7 @@ const Pagination = ({
       <button
         type="button"
         className={styles.arrow}
-        aria-label="다음 페이지"
+        aria-label={L.elements.nextPage}
         disabled={page >= totalPages}
         onClick={() => onChange(page + 1)}
       >
diff --git a/frontend/src/components/elements/SearchInput.tsx b/frontend/src/components/elements/SearchInput.tsx
index 614cd5c..6cfadc0 100644
--- a/frontend/src/components/elements/SearchInput.tsx
+++ b/frontend/src/components/elements/SearchInput.tsx
@@ -1,6 +1,7 @@
 import { Search } from "lucide-react";
 
 import { cn } from "@/utils/cn";
+import { L } from "@/locales";
 
 const styles = {
   wrap: "relative inline-flex h-8 w-full items-center rounded-[8px] border border-border-strong bg-well/70 transition-[border-color,box-shadow] duration-[160ms] focus-within:border-mint/60 focus-within:shadow-[0_0_0_3px] focus-within:shadow-mint/10",
@@ -29,7 +30,7 @@ interface SearchInputProps {
 const SearchInput = ({
   value,
   onChange,
-  placeholder = "검색",
+  placeholder = L.elements.search,
   maxLength,
   disabled = false,
   ariaLabel,
@@ -60,7 +61,7 @@ const SearchInput = ({
         <button
           type="button"
           className={styles.clear}
-          aria-label="지우기"
+          aria-label={L.elements.clear}
           onClick={() => onChange("")}
         >
           ✕
diff --git a/frontend/src/components/navigation/LanguageToggle.tsx b/frontend/src/components/navigation/LanguageToggle.tsx
new file mode 100644
index 0000000..4dbb9ce
--- /dev/null
+++ b/frontend/src/components/navigation/LanguageToggle.tsx
@@ -0,0 +1,28 @@
+import { Globe } from "lucide-react";
+
+import { language, setLanguage } from "@/locales";
+
+/**
+ * LanguageToggle is the always-visible navbar language switch (globe + label,
+ * the top-right convention users scan for). The label names the language it
+ * switches TO, in that language's own script, so a user stuck in the wrong
+ * language can still recognize the way out. setLanguage persists the choice
+ * and reloads — the locale is bound once at page load (see src/locales).
+ */
+const LanguageToggle = () => {
+  const nextLanguage = language === "ko" ? "en" : "ko";
+  const nextLanguageLabel = language === "ko" ? "English" : "한국어";
+
+  return (
+    <button
+      type="button"
+      className="text-muted-foreground hover:text-foreground flex cursor-pointer items-center gap-1.5 rounded px-2 py-1 text-sm"
+      onClick={() => setLanguage(nextLanguage)}
+    >
+      <Globe className="size-4" aria-hidden="true" />
+      {nextLanguageLabel}
+    </button>
+  );
+};
+
+export default LanguageToggle;
diff --git a/frontend/src/components/navigation/Navbar.tsx b/frontend/src/components/navigation/Navbar.tsx
index bae937e..cfc8e37 100644
--- a/frontend/src/components/navigation/Navbar.tsx
+++ b/frontend/src/components/navigation/Navbar.tsx
@@ -3,6 +3,7 @@ import { useQueryClient } from "@tanstack/react-query";
 
 import RuneMark from "@/components/elements/RuneMark";
 import WorkspaceStatus from "@/components/elements/WorkspaceStatus";
+import LanguageToggle from "@/components/navigation/LanguageToggle";
 import ProfileMenu from "@/components/navigation/ProfileMenu";
 import WorkspaceModal from "@/components/workspace/WorkspaceModal";
 import { useSessionQuery } from "@/hooks/queries/useSessionQuery";
@@ -13,6 +14,7 @@ import {
   PATH_LIST,
   QUERY_KEYS,
 } from "@/constants/commonConstants";
+import { L } from "@/locales";
 import { useWorkspaceStore } from "@/stores/workspaceStore";
 
 /**
@@ -64,21 +66,23 @@ const Navbar = () => {
             }`}
             onClick={workspace ? openModal : undefined}
           >
-            <span className="text-foreground text-sm">워크스페이스</span>
+            <span className="text-foreground text-sm">
+              {L.workspace.badgeLabel}
+            </span>
             {workspace ? (
               workspace.orphaned ? (
                 /* Reinstall detected: the workspace no longer matches this
                    console. Flag it so the badge doesn't read as healthy;
                    clicking opens the modal's 재생성 prompt. */
                 <span className="border-negative text-negative rounded border px-2 py-1 text-xs">
-                  재생성 필요
+                  {L.workspace.badgeRecreate}
                 </span>
               ) : workspace.reconnectRequired ? (
                 /* Data-plane credential expired: the cloud workspace is fine but
                    the local engine link is stale. Flag it (not the healthy pill);
                    clicking opens the modal's 재연결 prompt. */
                 <span className="border-warning text-warning rounded border px-2 py-1 text-xs">
-                  재연결 필요
+                  {L.workspace.badgeReconnect}
                 </span>
               ) : (
                 <WorkspaceStatus status={workspace.status} />
@@ -89,10 +93,11 @@ const Navbar = () => {
                 className="text-muted-foreground hover:text-foreground cursor-pointer rounded border px-2 py-1 text-xs"
                 onClick={() => navigate(PATH_LIST.workspace)}
               >
-                워크스페이스 없음
+                {L.workspace.badgeNone}
               </button>
             ) : null}
           </div>
+          <LanguageToggle />
           {me && <ProfileMenu me={me} onSignOut={handleSignOut} />}
         </div>
       </div>
diff --git a/frontend/src/components/navigation/ProfileMenu.tsx b/frontend/src/components/navigation/ProfileMenu.tsx
index ba66f14..d2455c7 100644
--- a/frontend/src/components/navigation/ProfileMenu.tsx
+++ b/frontend/src/components/navigation/ProfileMenu.tsx
@@ -2,6 +2,7 @@ import { useEffect, useRef, useState } from "react";
 
 import TextButton from "@/components/elements/TextButton";
 import { BTN_TEXT } from "@/constants/commonConstants";
+import { L } from "@/locales";
 
 interface ProfileMenuProps {
   // avatar is optional: the backend omits it when the principal has no picture,
@@ -59,7 +60,7 @@ const ProfileMenu = ({ me, onSignOut }: ProfileMenuProps) => {
         type="button"
         aria-haspopup="menu"
         aria-expanded={open}
-        aria-label="프로필 메뉴"
+        aria-label={L.profile.menu}
         className="block cursor-pointer rounded-full"
         onClick={() => setOpen((v) => !v)}
       >
@@ -68,7 +69,7 @@ const ProfileMenu = ({ me, onSignOut }: ProfileMenuProps) => {
         ) : (
           <img
             src={me.avatar}
-            alt="프로필 이미지"
+            alt={L.profile.image}
             className="size-8 rounded-full object-cover"
             onError={() => setImgError(true)}
           />
@@ -83,7 +84,7 @@ const ProfileMenu = ({ me, onSignOut }: ProfileMenuProps) => {
           <div className="text-foreground text-md truncate font-medium">
             {me.email}
           </div>
-          <div className="text-subtle text-sm">플랜: Free</div>
+          <div className="text-subtle text-sm">{L.profile.plan}</div>
           <hr className="border-border my-2" />
           <TextButton
             btnText={BTN_TEXT.signOut}
diff --git a/frontend/src/components/navigation/PublicNavbar.tsx b/frontend/src/components/navigation/PublicNavbar.tsx
index 4bcfbc1..1b02f88 100644
--- a/frontend/src/components/navigation/PublicNavbar.tsx
+++ b/frontend/src/components/navigation/PublicNavbar.tsx
@@ -2,6 +2,7 @@ import { Link, useLocation, useNavigate } from "react-router";
 
 import Button from "@/components/elements/Button";
 import RuneMark from "@/components/elements/RuneMark";
+import LanguageToggle from "@/components/navigation/LanguageToggle";
 import {
   BRAND_WORDMARK,
   BTN_TEXT,
@@ -31,15 +32,18 @@ const PublicNavbar = () => {
           <RuneMark />
           {BRAND_WORDMARK}
         </Link>
-        {!onLoginPage && (
-          <Button
-            btnText={BTN_TEXT.getStarted}
-            btnSize="sm"
-            btnColor="mintFilled"
-            handleClick={() => navigate(PATH_LIST.login)}
-            className="w-auto"
-          />
-        )}
+        <div className="flex items-center gap-4">
+          <LanguageToggle />
+          {!onLoginPage && (
+            <Button
+              btnText={BTN_TEXT.getStarted}
+              btnSize="sm"
+              btnColor="mintFilled"
+              handleClick={() => navigate(PATH_LIST.login)}
+              className="w-auto"
+            />
+          )}
+        </div>
       </div>
     </header>
   );
diff --git a/frontend/src/components/teams/AddMemberModal.tsx b/frontend/src/components/teams/AddMemberModal.tsx
index 518bfff..350ad35 100644
--- a/frontend/src/components/teams/AddMemberModal.tsx
+++ b/frontend/src/components/teams/AddMemberModal.tsx
@@ -14,6 +14,7 @@ import {
   validateUsername,
 } from "@/utils/username";
 import { BTN_TEXT, MODAL_TITLES } from "@/constants/commonConstants";
+import { L } from "@/locales";
 
 const EMAIL_PATTERN = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
 
@@ -56,37 +57,37 @@ const AddMemberModal = ({
       <div className="flex w-full flex-col gap-6">
         <Input
           id="add-member-account"
-          labelText="이메일 (account)"
+          labelText={L.teams.emailLabel}
           type="email"
           placeholder="user@corp.com"
           maxLength={100}
           value={account}
           setValue={setAccount}
-          error={invalidFormat ? "올바른 이메일 형식이 아닙니다." : undefined}
+          error={invalidFormat ? L.teams.invalidEmail : undefined}
         />
         <Input
           id="add-member-username"
-          labelText="사용자 이름 (username)"
-          placeholder="사용자 이름"
+          labelText={L.teams.usernameLabel}
+          placeholder={L.teams.usernamePlaceholder}
           maxLength={USERNAME_MAX_LENGTH}
           value={username}
           setValue={(value) => setUsername(normalizeUsernameInput(value))}
           error={usernameError}
         />
         <Dropdown
-          label="권한 (role)"
-          placeholder="권한 선택"
+          label={L.teams.roleLabel}
+          placeholder={L.teams.selectRole}
           options={ROLE_OPTIONS}
           value={role}
           onChange={setRole}
         />
         <Notice tone="info">
-          초대받은 사용자가 rune을 연결하면{" "}
+          {L.teams.invitePrefix}
           <MemberStatus
             status="online"
             className="bg-mint/10 h-auto cursor-default gap-1 rounded-sm px-1.5 py-0.5 align-middle"
           />
-          으로 전환됩니다.
+          {L.teams.inviteSuffix}
         </Notice>
         {error && <Notice tone="error">{error}</Notice>}
       </div>
diff --git a/frontend/src/components/teams/CreateTeamModal.tsx b/frontend/src/components/teams/CreateTeamModal.tsx
index fa91b3f..d3af9f7 100644
--- a/frontend/src/components/teams/CreateTeamModal.tsx
+++ b/frontend/src/components/teams/CreateTeamModal.tsx
@@ -11,6 +11,7 @@ import {
   TEAM_NAME_RULE_TEXT,
 } from "@/components/teams/teamOptions";
 import { BTN_TEXT, MODAL_TITLES } from "@/constants/commonConstants";
+import { L } from "@/locales";
 import type { TTeamTree } from "@/types/teamTypes";
 
 interface CreateTeamModalProps {
@@ -51,7 +52,7 @@ const CreateTeamModal = ({
   const nameError = isInvalidFormat
     ? TEAM_NAME_RULE_TEXT
     : trimmed && isDuplicate
-      ? "같은 상위 팀에 동일한 이름이 이미 있습니다."
+      ? L.teams.dupName
       : undefined;
 
   return (
@@ -59,8 +60,8 @@ const CreateTeamModal = ({
       <div className="flex w-full flex-col gap-5">
         <Input
           id="create-team-name"
-          labelText="팀 이름"
-          placeholder="예: platform-team"
+          labelText={L.teams.teamName}
+          placeholder={L.teams.teamNamePlaceholder}
           maxLength={50}
           value={name}
           setValue={setName}
@@ -68,15 +69,15 @@ const CreateTeamModal = ({
           error={nameError}
         />
         <Dropdown
-          label="상위 팀 (선택)"
-          placeholder="팀 선택"
+          label={L.teams.parentTeamOptional}
+          placeholder={L.teams.selectTeam}
           options={buildTeamOptions(teams)}
           value={parentId}
           onChange={setParentId}
         />
         <Notice tone="info">
-          상위 팀을 선택하면 상위 팀의 멤버가 새 팀에 자동 복사됩니다. <br />
-          멤버 편집은 팀 생성 후 상세 페이지에서 할 수 있습니다.
+          {L.teams.parentCopyInfo1} <br />
+          {L.teams.parentCopyInfo2}
         </Notice>
         {error && <Notice tone="error">{error}</Notice>}
       </div>
diff --git a/frontend/src/components/teams/DeleteTeamModal.tsx b/frontend/src/components/teams/DeleteTeamModal.tsx
index 9bef0a8..5a051a6 100644
--- a/frontend/src/components/teams/DeleteTeamModal.tsx
+++ b/frontend/src/components/teams/DeleteTeamModal.tsx
@@ -9,6 +9,7 @@ import ModalLayout from "@/components/layout/ModalLayout";
 import { buildTeamOptions } from "@/components/teams/teamOptions";
 import { cn } from "@/utils/cn";
 import { BTN_TEXT, MODAL_TITLES } from "@/constants/commonConstants";
+import { L } from "@/locales";
 import type { TTeamTree } from "@/types/teamTypes";
 
 const styles = {
@@ -69,9 +70,9 @@ const DeleteTeamModal = ({
     return (
       <ModalLayout title={MODAL_TITLES.deleteTeam(teamName)} isOpen>
         <p className="text-center text-base">
-          하위 팀이 있는 팀은 삭제할 수 없습니다.
+          {L.teams.hasChildrenAlert1}
           <br />
-          하위 팀을 먼저 삭제한 후 다시 시도해 주세요.
+          {L.teams.hasChildrenAlert2}
         </p>
         <Button
           btnText={BTN_TEXT.close}
@@ -113,9 +114,7 @@ const DeleteTeamModal = ({
   return (
     <ModalLayout title={MODAL_TITLES.deleteTeam(teamName)} isOpen isWide>
       <div className="flex w-full flex-col gap-4">
-        <Notice tone="info">
-          삭제하려는 팀의 기억 처리 방식을 선택해 주세요.
-        </Notice>
+        <Notice tone="info">{L.teams.memoryChoiceInfo}</Notice>
 
         {/* Option ① — transfer (default): the card is the selection area */}
         <div
@@ -129,14 +128,14 @@ const DeleteTeamModal = ({
             name="memory-action"
             checked={action === "transfer"}
             onChange={selectTransfer}
-            label="① 다른 팀으로 이전"
-            desc="(기본값)"
+            label={L.teams.transferOption}
+            desc={L.teams.defaultTag}
             className={styles.optionRadio}
           />
           <div className={styles.optionFields}>
             <Dropdown
-              label="이전받을 팀"
-              placeholder="팀 선택"
+              label={L.teams.destinationTeam}
+              placeholder={L.teams.selectTeam}
               options={targetOptions}
               value={targetTeamId}
               onChange={setTargetTeamId}
@@ -144,15 +143,13 @@ const DeleteTeamModal = ({
             />
             <Input
               id="delete-team-transfer-confirm"
-              labelText="확인 - 타겟 팀명 입력"
-              placeholder={targetName || "팀을 먼저 선택하세요"}
+              labelText={L.teams.confirmTargetLabel}
+              placeholder={targetName || L.teams.selectTeamFirst}
               maxLength={50}
               value={transferConfirm}
               setValue={setTransferConfirm}
               disabled={action !== "transfer"}
-              error={
-                transferMismatch ? "타겟 팀명이 일치하지 않습니다." : undefined
-              }
+              error={transferMismatch ? L.teams.targetNameMismatch : undefined}
             />
           </div>
         </div>
@@ -169,20 +166,20 @@ const DeleteTeamModal = ({
             name="memory-action"
             checked={action === "purge"}
             onChange={selectPurge}
-            label="② 팀 내 기억 삭제"
-            desc="다른 팀과 공유 중인 기억은 해당 팀에서 계속 조회할 수 있습니다."
+            label={L.teams.purgeOption}
+            desc={L.teams.purgeDesc}
             className={styles.optionRadio}
           />
           <div className={styles.optionFields}>
             <Input
               id="delete-team-purge-confirm"
-              labelText="확인 - 삭제할 팀명 입력"
+              labelText={L.teams.confirmDeleteLabel}
               placeholder={teamName}
               maxLength={50}
               value={purgeConfirm}
               setValue={setPurgeConfirm}
               disabled={action !== "purge"}
-              error={purgeMismatch ? "팀명이 일치하지 않습니다." : undefined}
+              error={purgeMismatch ? L.teams.nameMismatch : undefined}
             />
           </div>
         </div>
diff --git a/frontend/src/components/teams/OrgChart.tsx b/frontend/src/components/teams/OrgChart.tsx
index 4d6342a..de8fff1 100644
--- a/frontend/src/components/teams/OrgChart.tsx
+++ b/frontend/src/components/teams/OrgChart.tsx
@@ -1,6 +1,7 @@
 import { useMemo, useState } from "react";
 
 import { cn } from "@/utils/cn";
+import { L } from "@/locales";
 import type { TTeamNode, TTeamTree } from "@/types/teamTypes";
 
 const styles = {
@@ -139,7 +140,7 @@ const OrgNode = ({
           connector === "none" && rootBorderById.get(node.id),
           isMatch && styles.orgBoxMatch,
         )}
-        aria-label={`${node.name} 상세 보기`}
+        aria-label={L.teams.viewDetails(node.name)}
         onClick={() => onSelect(node.id)}
       >
         <b className={styles.orgBoxName} title={node.name}>
@@ -235,7 +236,7 @@ const OrgChart = ({ teams, query, onSelectTeam }: OrgChartProps) => {
         <button
           type="button"
           className={styles.zoomButton}
-          aria-label="축소"
+          aria-label={L.teams.zoomOut}
           disabled={zoomStep >= ZOOM_SCALES.length - 1}
           onClick={() => setZoomStep((step) => step + 1)}
         >
@@ -245,7 +246,7 @@ const OrgChart = ({ teams, query, onSelectTeam }: OrgChartProps) => {
         <button
           type="button"
           className={styles.zoomButton}
-          aria-label="확대"
+          aria-label={L.teams.zoomIn}
           disabled={zoomStep === 0}
           onClick={() => setZoomStep((step) => step - 1)}
         >
diff --git a/frontend/src/components/teams/RemoveMembershipModal.tsx b/frontend/src/components/teams/RemoveMembershipModal.tsx
index 5fb8d92..4535262 100644
--- a/frontend/src/components/teams/RemoveMembershipModal.tsx
+++ b/frontend/src/components/teams/RemoveMembershipModal.tsx
@@ -2,6 +2,7 @@ import Button from "@/components/elements/Button";
 import Notice from "@/components/elements/Notice";
 import ModalLayout from "@/components/layout/ModalLayout";
 import { BTN_TEXT, MODAL_TITLES } from "@/constants/commonConstants";
+import { L } from "@/locales";
 import type { TTeamMemberRole } from "@/types/teamTypes";
 
 export interface TMembershipRemoval {
@@ -37,13 +38,13 @@ const RemoveMembershipModal = ({
   return (
     <ModalLayout title={MODAL_TITLES.removeMembership} isOpen>
       <div className="flex w-full flex-col gap-4">
-        <p className="text-base">다음 멤버십을 제거합니다:</p>
+        <p className="text-base">{L.teams.removeIntro}</p>
         <table className={styles.table}>
           <thead>
             <tr>
-              <th className={styles.th}>멤버 이름</th>
-              <th className={styles.th}>팀</th>
-              <th className={styles.th}>권한</th>
+              <th className={styles.th}>{L.common.memberName}</th>
+              <th className={styles.th}>{L.common.team}</th>
+              <th className={styles.th}>{L.common.role}</th>
             </tr>
           </thead>
           <tbody>
@@ -56,9 +57,7 @@ const RemoveMembershipModal = ({
             ))}
           </tbody>
         </table>
-        <Notice tone="info">
-          하위 팀 소속은 유지됩니다. 필요할 경우 개별 선택 후 제거하세요.
-        </Notice>
+        <Notice tone="info">{L.teams.removeKeepSubteams}</Notice>
       </div>
       <div className="flex w-full gap-2">
         <Button
diff --git a/frontend/src/components/teams/RenameTeamModal.tsx b/frontend/src/components/teams/RenameTeamModal.tsx
index 828c00e..34ea290 100644
--- a/frontend/src/components/teams/RenameTeamModal.tsx
+++ b/frontend/src/components/teams/RenameTeamModal.tsx
@@ -9,6 +9,7 @@ import {
   TEAM_NAME_RULE_TEXT,
 } from "@/components/teams/teamOptions";
 import { BTN_TEXT, MODAL_TITLES } from "@/constants/commonConstants";
+import { L } from "@/locales";
 import type { TTeamTree } from "@/types/teamTypes";
 
 interface RenameTeamModalProps {
@@ -58,7 +59,7 @@ const RenameTeamModal = ({
   const nameError = isInvalidFormat
     ? TEAM_NAME_RULE_TEXT
     : isDuplicate
-      ? "같은 상위 팀에 동일한 이름이 이미 있습니다."
+      ? L.teams.dupName
       : undefined;
 
   return (
@@ -66,7 +67,7 @@ const RenameTeamModal = ({
       <div className="flex w-full flex-col gap-5">
         <Input
           id="rename-team-name"
-          labelText="팀 이름"
+          labelText={L.teams.teamName}
           maxLength={50}
           value={name}
           setValue={setName}
diff --git a/frontend/src/components/teams/RoleChangeConfirmModal.tsx b/frontend/src/components/teams/RoleChangeConfirmModal.tsx
index 0771021..98ea2e2 100644
--- a/frontend/src/components/teams/RoleChangeConfirmModal.tsx
+++ b/frontend/src/components/teams/RoleChangeConfirmModal.tsx
@@ -1,6 +1,7 @@
 import Button from "@/components/elements/Button";
 import ModalLayout from "@/components/layout/ModalLayout";
 import { BTN_TEXT, MODAL_TITLES } from "@/constants/commonConstants";
+import { L } from "@/locales";
 
 export interface TRoleChange {
   account: string;
@@ -35,12 +36,12 @@ const RoleChangeConfirmModal = ({
   return (
     <ModalLayout title={MODAL_TITLES.roleChange} isOpen>
       <div className="flex w-full flex-col gap-4">
-        <p className="text-base">다음 멤버의 권한을 변경합니다:</p>
+        <p className="text-base">{L.teams.roleChangeIntro}</p>
         <table className={styles.table}>
           <thead>
             <tr>
-              <th className={styles.th}>멤버 이름</th>
-              <th className={styles.th}>권한 변경</th>
+              <th className={styles.th}>{L.common.memberName}</th>
+              <th className={styles.th}>{L.teams.roleChangeCol}</th>
             </tr>
           </thead>
           <tbody>
diff --git a/frontend/src/components/teams/TreeDetailView.tsx b/frontend/src/components/teams/TreeDetailView.tsx
index c1d4068..11fe775 100644
--- a/frontend/src/components/teams/TreeDetailView.tsx
+++ b/frontend/src/components/teams/TreeDetailView.tsx
@@ -37,6 +37,7 @@ import { parseErrorCode } from "@/api/parseError";
 import { CHIP_STATUS } from "@/components/users/memberStatusMap";
 import { formatDate } from "@/utils/formatDate";
 import { BTN_TEXT, MODAL_TITLES } from "@/constants/commonConstants";
+import { L } from "@/locales";
 import type { TTeamNode } from "@/types/commonTypes";
 import type { TTeamMemberRole, TTeamTree } from "@/types/teamTypes";
 import { useNoticeStore } from "@/stores/noticeStore";
@@ -187,12 +188,14 @@ const TreeDetailView = ({
 
   const flatTeam = flatById.get(selectedTeam.id);
   const parentName = detail?.parentId
-    ? (flatById.get(detail.parentId)?.name ?? "없음")
+    ? (flatById.get(detail.parentId)?.name ?? L.common.none)
     : flatTeam?.parentId
-      ? (flatById.get(flatTeam.parentId)?.name ?? "없음")
-      : "없음";
+      ? (flatById.get(flatTeam.parentId)?.name ?? L.common.none)
+      : L.common.none;
   const childCount = detail?.children.length ?? flatTeam?.childCount ?? 0;
-  const childrenLabel = childCount ? `${childCount}개` : "없음";
+  const childrenLabel = childCount
+    ? L.teams.countItems(childCount)
+    : L.common.none;
   const memberCount = detail?.memberCount ?? selectedTeam.members;
 
   /* Select-all is page-scoped; selections persist across page moves. */
@@ -236,11 +239,7 @@ const TreeDetailView = ({
   const applyRoleChanges = () => {
     setSavedRoles((prev) => new Map([...prev, ...pendingRoles]));
     setPendingRoles(new Map());
-    showNotice(
-      MODAL_TITLES.roleChange,
-      "변경사항이 저장되었습니다.",
-      "success",
-    );
+    showNotice(MODAL_TITLES.roleChange, L.teams.changesSaved, "success");
   };
 
   /* Modals (SC-07~10 + SC-06 state E). All confirm handlers below call
@@ -261,9 +260,9 @@ const TreeDetailView = ({
     closeModal();
   };
   const TEAM_REASON: Record<string, string> = {
-    TEAM_NAME_DUPLICATE: "같은 상위 팀에 동일한 이름이 이미 있습니다.",
-    TEAM_NAME_INVALID: "팀 이름 형식이 올바르지 않습니다.",
-    TEAM_HAS_CHILDREN: "하위 팀이 있어 삭제할 수 없습니다.",
+    TEAM_NAME_DUPLICATE: L.teams.dupName,
+    TEAM_NAME_INVALID: L.teams.invalidTeamName,
+    TEAM_HAS_CHILDREN: L.teams.cannotDeleteHasChildren,
   };
 
   /* Partial-failure surface for the two batch endpoints (role change,
@@ -273,21 +272,21 @@ const TreeDetailView = ({
     { account: string; reason: string }[] | null
   >(null);
   const BATCH_REASON: Record<string, string> = {
-    USER_NOT_FOUND: "사용자를 찾을 수 없습니다",
-    NOT_TEAM_MEMBER: "팀 멤버가 아닙니다",
+    USER_NOT_FOUND: L.teams.userNotFound,
+    NOT_TEAM_MEMBER: L.teams.notTeamMember,
   };
   // Any other code (e.g. a transient INTERNAL) shows a generic retry message
   // instead of leaking the raw backend code into the failure modal.
-  const BATCH_REASON_FALLBACK = "처리에 실패했습니다. 다시 시도해 주세요.";
+  const BATCH_REASON_FALLBACK = L.common.processFailed;
   const accountOf = (userId: string) =>
     members.find((m) => m.userId === userId)?.account ?? userId;
 
   const [addError, setAddError] = useState<string | null>(null);
   const ADD_REASON: Record<string, string> = {
-    ALREADY_TEAM_MEMBER: "이미 초대된 사용자입니다.",
-    USER_NOT_FOUND: "등록되지 않은 계정입니다.",
-    CANNOT_INVITE_ADMIN: "콘솔 관리자 계정은 추가할 수 없습니다.",
-    MAIL_UPSTREAM_ERROR: "초대 코드 전송에 실패했습니다. 다시 시도해 주세요.",
+    ALREADY_TEAM_MEMBER: L.teams.alreadyInvited,
+    USER_NOT_FOUND: L.teams.notRegistered,
+    CANNOT_INVITE_ADMIN: L.teams.cannotAddAdmin,
+    MAIL_UPSTREAM_ERROR: L.teams.inviteSendFailed,
   };
 
   const roleChanges = [...pendingRoles.entries()].map(([userId, to]) => {
@@ -306,11 +305,11 @@ const TreeDetailView = ({
       {
         onSuccess: () => {
           closeModal();
-          showNotice("팀 생성", "팀이 생성되었습니다.", "success");
+          showNotice(L.teams.createTeamTitle, L.teams.teamCreated, "success");
         },
         onError: async (res) => {
           const code = await parseErrorCode(res);
-          setTeamError(TEAM_REASON[code] ?? "팀 생성에 실패했습니다.");
+          setTeamError(TEAM_REASON[code] ?? L.teams.createTeamFailed);
         },
       },
     );
@@ -322,11 +321,11 @@ const TreeDetailView = ({
       {
         onSuccess: () => {
           closeModal();
-          showNotice("팀 이름 변경", "팀 이름이 변경되었습니다.", "success");
+          showNotice(MODAL_TITLES.renameTeam, L.teams.teamRenamed, "success");
         },
         onError: async (res) => {
           const code = await parseErrorCode(res);
-          setTeamError(TEAM_REASON[code] ?? "이름 변경에 실패했습니다.");
+          setTeamError(TEAM_REASON[code] ?? L.teams.renameFailed);
         },
       },
     );
@@ -341,16 +340,22 @@ const TreeDetailView = ({
       {
         onSuccess: () => {
           closeModal();
-          showNotice("팀 삭제", "팀이 삭제되었습니다.", "success", () => {
-            onSelectTeam(
-              teams.find((t) => t.parentId === null && t.id !== selectedTeam.id)
-                ?.id ?? "",
-            );
-          });
+          showNotice(
+            L.teams.deleteTeamTitle,
+            L.teams.teamDeleted,
+            "success",
+            () => {
+              onSelectTeam(
+                teams.find(
+                  (t) => t.parentId === null && t.id !== selectedTeam.id,
+                )?.id ?? "",
+              );
+            },
+          );
         },
         onError: async (res) => {
           const code = await parseErrorCode(res);
-          setTeamError(TEAM_REASON[code] ?? "팀 삭제에 실패했습니다.");
+          setTeamError(TEAM_REASON[code] ?? L.teams.deleteFailed);
         },
       },
     );
@@ -362,11 +367,11 @@ const TreeDetailView = ({
       {
         onSuccess: () => {
           closeModal();
-          showNotice("멤버 추가", "멤버를 추가했습니다.", "success");
+          showNotice(L.teams.addMemberTitle, L.teams.memberAdded, "success");
         },
         onError: async (res) => {
           const code = await parseErrorCode(res);
-          setAddError(ADD_REASON[code] ?? "멤버 추가에 실패했습니다.");
+          setAddError(ADD_REASON[code] ?? L.teams.addMemberFailed);
         },
       },
     );
@@ -410,11 +415,7 @@ const TreeDetailView = ({
         },
         onError: () => {
           closeModal();
-          showNotice(
-            MODAL_TITLES.roleChange,
-            "권한 변경에 실패했습니다.",
-            "error",
-          );
+          showNotice(MODAL_TITLES.roleChange, L.teams.roleChangeFailed, "error");
         },
       },
     );
@@ -435,7 +436,7 @@ const TreeDetailView = ({
         } else {
           showNotice(
             MODAL_TITLES.removeMembership,
-            "멤버십이 제거되었습니다.",
+            L.teams.membershipsRemoved,
             "success",
           );
         }
@@ -444,7 +445,7 @@ const TreeDetailView = ({
         closeModal();
         showNotice(
           MODAL_TITLES.removeMembership,
-          "멤버십 제거에 실패했습니다.",
+          L.teams.removeFailed,
           "error",
         );
       },
@@ -464,7 +465,7 @@ const TreeDetailView = ({
     <div className={styles.body}>
       {/* Left panel — create + tree (SC-06 no.3–5); search lives in the
           TeamsPage header */}
-      <aside className={styles.side} aria-label="팀 트리">
+      <aside className={styles.side} aria-label={L.teams.teamTree}>
         <Button
           btnText={BTN_TEXT.createGroup}
           btnSize="sm"
@@ -508,13 +509,17 @@ const TreeDetailView = ({
             />
           </div>
           <p className={styles.teamMeta}>
-            상위 팀: {parentName} | 하위 팀: {childrenLabel} | 멤버:{" "}
-            {memberCount}명 | 생성일: {formatDate(detail?.createdAt)}
+            {L.teams.teamMeta(
+              parentName,
+              childrenLabel,
+              memberCount,
+              formatDate(detail?.createdAt),
+            )}
           </p>
         </div>
 
         <div className={styles.membersRow}>
-          <h3 className={styles.membersTitle}>멤버 ({total})</h3>{" "}
+          <h3 className={styles.membersTitle}>{L.teams.membersHeading(total)}</h3>{" "}
           <div className={styles.pendingActions}>
             {/* Drops every staged (not yet applied) dropdown pick back to
                 its saved role — the committed savedRoles baseline stays. */}
@@ -557,7 +562,7 @@ const TreeDetailView = ({
           scrollClassName="min-h-[526px]"
           foot={
             <TableFoot
-              info={`총 ${total}명 · ${PAGE_SIZE}명/페이지`}
+              info={L.teams.memberPageInfo(total, PAGE_SIZE)}
               className="flex-row items-center"
             >
               <div className="flex flex-col items-end gap-3">
@@ -575,15 +580,23 @@ const TreeDetailView = ({
               <Checkbox
                 checked={allSelected}
                 onChange={toggleAll}
-                ariaLabel="전체 선택"
+                ariaLabel={L.common.selectAll}
               />
             </TableHeaderCell>
             {/* Fixed column widths — auto layout would resize per
                 page's content and shift the headers while paginating. */}
-            <TableHeaderCell className="w-[36%]">멤버 이름</TableHeaderCell>
-            <TableHeaderCell className="w-[18%]">멤버 상태</TableHeaderCell>
-            <TableHeaderCell className="w-[28%]">역할</TableHeaderCell>
-            <TableHeaderCell className="w-[18%]">합류일</TableHeaderCell>
+            <TableHeaderCell className="w-[36%]">
+              {L.common.memberName}
+            </TableHeaderCell>
+            <TableHeaderCell className="w-[18%]">
+              {L.common.memberStatus}
+            </TableHeaderCell>
+            <TableHeaderCell className="w-[28%]">
+              {L.teams.roleHeader}
+            </TableHeaderCell>
+            <TableHeaderCell className="w-[18%]">
+              {L.teams.joinedAt}
+            </TableHeaderCell>
           </TableHead>
           <tbody>
             {membersQuery.isPending ? (
@@ -592,21 +605,18 @@ const TreeDetailView = ({
                   colSpan={5}
                   className="text-faint px-3 py-6 text-center text-sm"
                 >
-                  불러오는 중…
+                  {L.common.loading}
                 </td>
               </tr>
             ) : membersQuery.isError ? (
-              <TableErrorRow
-                message="멤버 목록을 불러올 수 없습니다."
-                colSpan={5}
-              />
+              <TableErrorRow message={L.teams.membersLoadError} colSpan={5} />
             ) : total === 0 ? (
               <tr>
                 <td
                   colSpan={5}
                   className="text-faint px-3 py-6 text-center text-sm"
                 >
-                  멤버가 없습니다.
+                  {L.teams.noMembers}
                 </td>
               </tr>
             ) : (
@@ -620,7 +630,7 @@ const TreeDetailView = ({
                     <Checkbox
                       checked={selectedIds.has(member.userId)}
                       onChange={(checked) => toggleOne(member.userId, checked)}
-                      ariaLabel={`${member.account} 선택`}
+                      ariaLabel={L.common.selectName(member.account)}
                     />
                   </TableCell>
                   <TableCell className={styles.usernameCell}>
diff --git a/frontend/src/components/teams/teamOptions.ts b/frontend/src/components/teams/teamOptions.ts
index 2415780..1e66655 100644
--- a/frontend/src/components/teams/teamOptions.ts
+++ b/frontend/src/components/teams/teamOptions.ts
@@ -1,11 +1,11 @@
+import { L } from "@/locales";
 import type { TDropdownOption } from "@/types/commonTypes";
 import type { TTeamTree } from "@/types/teamTypes";
 
 /** Team name rule: digits, Hangul, Latin letters, and - _ only. */
 export const TEAM_NAME_PATTERN = /^[0-9A-Za-z가-힣_-]+$/;
 
-export const TEAM_NAME_RULE_TEXT =
-  "숫자·한글·영어와 - _ 만 사용할 수 있습니다.";
+export const TEAM_NAME_RULE_TEXT = L.teams.teamNameRule;
 
 /** Grantable member roles (Admin is console-account only — API §0). */
 export const ROLE_OPTIONS: TDropdownOption[] = [
diff --git a/frontend/src/components/toast/ToastContainer.tsx b/frontend/src/components/toast/ToastContainer.tsx
index 15c30f9..713a7ec 100644
--- a/frontend/src/components/toast/ToastContainer.tsx
+++ b/frontend/src/components/toast/ToastContainer.tsx
@@ -1,6 +1,7 @@
 import { createPortal } from "react-dom";
 
 import { cn } from "@/utils/cn";
+import { L } from "@/locales";
 import { useToastStore } from "@/stores/toastStore";
 
 const styles = {
@@ -33,7 +34,7 @@ const ToastContainer = () => {
           key={toast.id}
           role={toast.tone === "error" ? "alert" : "status"}
           className={cn(styles.toast, toast.leaving && styles.toastLeaving)}
-          title="클릭하여 닫기"
+          title={L.elements.clickToDismiss}
           onClick={() => dismissToast(toast.id)}
         >
           <span
diff --git a/frontend/src/components/tree/TeamTree.tsx b/frontend/src/components/tree/TeamTree.tsx
index f9db366..15e8208 100644
--- a/frontend/src/components/tree/TeamTree.tsx
+++ b/frontend/src/components/tree/TeamTree.tsx
@@ -3,6 +3,7 @@ import { useMemo, useState } from "react";
 import Feedback from "@/components/elements/Feedback";
 import TreeNode from "@/components/tree/TreeNode";
 import { cn } from "@/utils/cn";
+import { L } from "@/locales";
 import type { TTeamNode } from "@/types/commonTypes";
 
 interface TeamTreeProps {
@@ -62,8 +63,8 @@ const TeamTree = ({
   onSelect,
   query = "",
   defaultExpandedIds = [],
-  emptyTitle = "검색 결과가 없습니다.",
-  emptyDescription = "팀 이름을 다시 확인해 주세요.",
+  emptyTitle = L.common.noResults,
+  emptyDescription = L.teams.checkTeamName,
   className,
 }: TeamTreeProps) => {
   const [expanded, setExpanded] = useState(() => new Set(defaultExpandedIds));
diff --git a/frontend/src/components/tree/TreeNode.tsx b/frontend/src/components/tree/TreeNode.tsx
index 76bda3a..06b35d9 100644
--- a/frontend/src/components/tree/TreeNode.tsx
+++ b/frontend/src/components/tree/TreeNode.tsx
@@ -3,6 +3,7 @@ import type { CSSProperties } from "react";
 import IconMinus from "@/components/icons/IconMinus";
 import IconPlus from "@/components/icons/IconPlus";
 import { cn } from "@/utils/cn";
+import { L } from "@/locales";
 import type { TTeamNode } from "@/types/commonTypes";
 
 const styles = {
@@ -81,7 +82,11 @@ const TreeNode = ({
           <button
             type="button"
             className={styles.toggle}
-            aria-label={`${node.name} ${isOpen ? "접기" : "펼치기"}`}
+            aria-label={
+              isOpen
+                ? L.teams.collapseName(node.name)
+                : L.teams.expandName(node.name)
+            }
             aria-expanded={isOpen}
             onClick={() => onToggle(node.id)}
           >
diff --git a/frontend/src/components/update/UpdateFloatingCard.tsx b/frontend/src/components/update/UpdateFloatingCard.tsx
index 573d808..35ceb7a 100644
--- a/frontend/src/components/update/UpdateFloatingCard.tsx
+++ b/frontend/src/components/update/UpdateFloatingCard.tsx
@@ -10,6 +10,7 @@ import {
 } from "@/hooks/queries/useUpdateQuery";
 import { reloadPage } from "@/utils/reloadPage";
 import { BTN_TEXT } from "@/constants/commonConstants";
+import { L } from "@/locales";
 
 const DISMISSED_KEY_PREFIX = "runeconsole.system-update.dismissed:";
 const QUEUED_TARGET_KEY = "runeconsole.system-update.queued-target";
@@ -129,10 +130,10 @@ const UpdateFloatingCard = () => {
   };
 
   const title = busy
-    ? "콘솔을 업데이트하는 중입니다"
+    ? L.workspace.updatingTitle
     : failed
-      ? "업데이트에 실패했습니다"
-      : "새 버전이 출시되었습니다";
+      ? L.workspace.updateFailedTitle
+      : L.workspace.newVersionTitle;
 
   return (
     <aside
@@ -158,18 +159,14 @@ const UpdateFloatingCard = () => {
           <IconSpinner className="text-mint size-5 flex-none" />
           <span>
             {status.state === "running"
-              ? "백업 및 업데이트를 진행하고 있습니다…"
-              : "업데이트를 준비하고 있습니다…"}
+              ? L.workspace.updateRunning
+              : L.workspace.updatePreparing}
           </span>
         </div>
       ) : failed ? (
-        <Notice tone="error">
-          업데이트를 완료하지 못했습니다. 상태를 확인한 뒤 다시 시도해 주세요.
-        </Notice>
+        <Notice tone="error">{L.workspace.updateFailedBody}</Notice>
       ) : (
-        <Notice>
-          콘솔이 재시작되는 동안 RUNE 사용이 일시적으로 중단될 수 있습니다.
-        </Notice>
+        <Notice>{L.workspace.updateRestartNotice}</Notice>
       )}
 
       {!busy &&
diff --git a/frontend/src/components/users/CancelInvitationModal.tsx b/frontend/src/components/users/CancelInvitationModal.tsx
index dc05f8e..c893224 100644
--- a/frontend/src/components/users/CancelInvitationModal.tsx
+++ b/frontend/src/components/users/CancelInvitationModal.tsx
@@ -3,6 +3,7 @@ import { useState } from "react";
 import Button from "@/components/elements/Button";
 import ModalLayout from "@/components/layout/ModalLayout";
 import { BTN_TEXT, MODAL_TITLES } from "@/constants/commonConstants";
+import { L } from "@/locales";
 
 interface CancelInvitationModalProps {
   account: string;
@@ -38,8 +39,8 @@ const CancelInvitationModal = ({
   return (
     <ModalLayout title={MODAL_TITLES.cancelInvitation} isOpen>
       <p className="text-center text-base">
-        {account}의 미사용 초대 코드가 모두 만료됩니다. <br />
-        유저는 삭제되지 않습니다.
+        {L.members.cancelInviteExpires(account)} <br />
+        {L.members.userNotDeleted}
       </p>
       <div className="flex w-full items-center gap-4">
         <Button
diff --git a/frontend/src/components/users/InviteMemberModal.tsx b/frontend/src/components/users/InviteMemberModal.tsx
index f56e639..fce55ee 100644
--- a/frontend/src/components/users/InviteMemberModal.tsx
+++ b/frontend/src/components/users/InviteMemberModal.tsx
@@ -16,6 +16,7 @@ import {
   validateUsername,
 } from "@/utils/username";
 import { BTN_TEXT, MODAL_TITLES } from "@/constants/commonConstants";
+import { L } from "@/locales";
 import type { TTeamTree } from "@/types/teamTypes";
 import type { TInvitePayload, TInviteResult } from "@/types/userTypes";
 
@@ -30,10 +31,9 @@ const styles = {
 /** Complete email format — validated on blur (SC-12 no.1). */
 const EMAIL_PATTERN = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
 
-const EMAIL_FORMAT_ERROR = "올바른 이메일 형식이 아닙니다";
-const DUPLICATE_ACCOUNT_ERROR =
-  "이미 등록된 계정입니다. 멤버 추가 또는 초대 코드 재전송을 사용하세요.";
-const SEND_FAILED_MESSAGE = "초대 전송에 실패했습니다. 다시 시도해 주세요.";
+const EMAIL_FORMAT_ERROR = L.members.emailFormatError;
+const DUPLICATE_ACCOUNT_ERROR = L.members.duplicateAccount;
+const SEND_FAILED_MESSAGE = L.members.sendFailed;
 
 /** One editable team/role set row; id keys the row across removals. */
 type TSetDraft = { id: number; teamId: string; role: string };
@@ -147,7 +147,7 @@ const InviteMemberModal = ({
         <Input
           id="invite-email"
           type="email"
-          labelText="이메일 (account)"
+          labelText={L.teams.emailLabel}
           placeholder="user@corp.com"
           maxLength={100}
           value={email}
@@ -161,8 +161,8 @@ const InviteMemberModal = ({
 
         <Input
           id="invite-username"
-          labelText="사용자 이름 (username)"
-          placeholder="사용자 이름"
+          labelText={L.teams.usernameLabel}
+          placeholder={L.teams.usernamePlaceholder}
           maxLength={USERNAME_MAX_LENGTH}
           value={username}
           setValue={(value) => setUsername(normalizeUsernameInput(value))}
@@ -170,25 +170,25 @@ const InviteMemberModal = ({
         />
 
         <div className="flex flex-col gap-2">
-          <span className={styles.fieldLabel}>팀 / 권한</span>
+          <span className={styles.fieldLabel}>{L.members.teamRole}</span>
           {sets.map((set, index) => (
             <div key={set.id} className={styles.setRow}>
               <div className={styles.teamSlot}>
                 <Dropdown
                   options={teamOptionsFor(set.id)}
-                  placeholder="팀 선택"
+                  placeholder={L.members.selectTeam}
                   value={set.teamId}
                   onChange={(teamId) => patchSet(set.id, { teamId })}
-                  ariaLabel={`세트 ${index + 1} 팀`}
+                  ariaLabel={L.members.setTeamAria(index + 1)}
                 />
               </div>
               <div className={styles.roleSlot}>
                 <Dropdown
                   options={ROLE_OPTIONS}
-                  placeholder="권한 선택"
+                  placeholder={L.members.selectRole}
                   value={set.role}
                   onChange={(role) => patchSet(set.id, { role })}
-                  ariaLabel={`세트 ${index + 1} role`}
+                  ariaLabel={L.members.setRoleAria(index + 1)}
                 />
               </div>
               {/* First set is required and carries no remove button
@@ -219,9 +219,9 @@ const InviteMemberModal = ({
 
         {showPreview && (
           <div className="flex flex-col gap-2">
-            <span className={styles.fieldLabel}>하위 팀 권한 미리보기</span>
+            <span className={styles.fieldLabel}>{L.members.subteamPreview}</span>
             <ModalTable
-              head={["팀", "권한", "사유"]}
+              head={[L.common.team, L.common.role, L.members.reason]}
               rows={previewRows.map((row) => [
                 row.indent ? `└ ${row.teamName}` : row.teamName,
                 row.role,
@@ -235,14 +235,12 @@ const InviteMemberModal = ({
           <Notice tone="error">{SEND_FAILED_MESSAGE}</Notice>
         ) : (
           <Notice>
-            초대 시 사용자에게 초대 코드가 발송되어 사용자가 24시간 내 rune을
-            연결하면{" "}
+            {L.members.invitePrefix}
             <MemberStatus
               status="online"
               className="h-auto cursor-default p-0 align-middle"
-            />{" "}
-            으로 전환됩니다. <br /> 미연결 시 코드가 만료되고 초대 코드
-            재전송으로 사용자를 다시 초대할 수 있습니다.
+            />
+            {L.members.inviteSuffix} <br /> {L.members.inviteExpiry}
           </Notice>
         )}
       </div>
diff --git a/frontend/src/components/users/MemberDeleteModal.tsx b/frontend/src/components/users/MemberDeleteModal.tsx
index c6ec85d..35912d3 100644
--- a/frontend/src/components/users/MemberDeleteModal.tsx
+++ b/frontend/src/components/users/MemberDeleteModal.tsx
@@ -4,9 +4,10 @@ import Button from "@/components/elements/Button";
 import ModalLayout from "@/components/layout/ModalLayout";
 import ModalTable from "@/components/users/ModalTable";
 import { BTN_TEXT, MODAL_TITLES } from "@/constants/commonConstants";
+import { L } from "@/locales";
 import type { TMemberDeleteTarget } from "@/types/userTypes";
 
-const DELETE_FAILED_MESSAGE = "멤버 삭제에 실패했습니다. 다시 시도해 주세요.";
+const DELETE_FAILED_MESSAGE = L.members.deleteFailed;
 
 /** The team/role table, or the empty-state line when the target belongs
     to no team (no group-role membership). */
@@ -15,13 +16,13 @@ const memberTeams = (memberships: TMemberDeleteTarget["memberships"]) =>
     /* table-fixed: the 팀/권한 columns split 50/50 regardless of content,
        so the per-user tables all line up. */
     <ModalTable
-      head={["팀", "권한"]}
+      head={[L.common.team, L.common.role]}
       rows={memberships.map((m) => [m.teamName, m.role])}
       className="table-fixed"
     />
   ) : (
     <p className="text-muted-foreground border p-2 text-sm">
-      소속된 팀이 없습니다.
+      {L.members.noTeams}
     </p>
   );
 
@@ -88,15 +89,13 @@ const MemberDeleteModal = ({
         {single ? (
           <>
             <p className="text-base">
-              {single.account} 계정을 삭제하며, 아래 팀에서 제거됩니다:
+              {L.members.deleteSingleIntro(single.account)}
             </p>
             {memberTeams(single.memberships)}
           </>
         ) : (
           <>
-            <p className="text-base">
-              다음 멤버의 계정을 삭제하며, 아래 팀에서 제거됩니다:
-            </p>
+            <p className="text-base">{L.members.deleteBulkIntro}</p>
             {targets.map((target) => (
               <div key={target.account} className="flex flex-col gap-2">
                 <b className="text-sm">{target.account}</b>
diff --git a/frontend/src/components/users/MemberDetailDrawer.tsx b/frontend/src/components/users/MemberDetailDrawer.tsx
index 1d711e4..fbc4a38 100644
--- a/frontend/src/components/users/MemberDetailDrawer.tsx
+++ b/frontend/src/components/users/MemberDetailDrawer.tsx
@@ -25,6 +25,7 @@ import { parseErrorCode } from "@/api/parseError";
 import { formatDate, formatDateTime } from "@/utils/formatDate";
 import { BTN_TEXT, MODAL_TITLES } from "@/constants/commonConstants";
 import { INVITATION_STATUS_VAR } from "@/constants/styleConstants";
+import { L } from "@/locales";
 import type { TBatchResult, TTeamTree } from "@/types/teamTypes";
 import type { TUserListItem } from "@/types/userTypes";
 import { useNoticeStore } from "@/stores/noticeStore";
@@ -47,14 +48,14 @@ const styles = {
     an online member shows last access; otherwise the invitation axis drives it. */
 const subtitleFor = (user: TUserListItem): string => {
   if (user.sessionStatus === "online") {
-    return `최근 접속 ${formatDate(user.lastAccessAt)}`;
+    return L.members.lastAccessed(formatDate(user.lastAccessAt));
   }
   switch (user.invitationStatus) {
     case "invite_redeemed":
-      return "초대 코드 사용됨 · 연결 대기 중";
+      return L.members.redeemedAwaiting;
     case "invite_pending":
     case "invite_expired":
-      return `최근 초대 코드 발송 ${formatDateTime(user.lastInvitedAt)}`;
+      return L.members.lastInviteSentAt(formatDateTime(user.lastInvitedAt));
   }
 };
 
@@ -78,12 +79,12 @@ type TDrawerModal =
 /** Batch-endpoint failure reasons shown by team name (SC-13 — shared
     with the team-side codes; the drawer only ever sees these two). */
 const BATCH_REASON: Record<string, string> = {
-  TEAM_NOT_FOUND: "팀을 찾을 수 없습니다",
-  NOT_TEAM_MEMBER: "팀 멤버가 아닙니다",
+  TEAM_NOT_FOUND: L.members.teamNotFound,
+  NOT_TEAM_MEMBER: L.teams.notTeamMember,
 };
 // Any other code (e.g. a transient INTERNAL) shows a generic retry message
 // rather than leaking the raw backend code into the failure modal.
-const BATCH_REASON_FALLBACK = "처리에 실패했습니다. 다시 시도해 주세요.";
+const BATCH_REASON_FALLBACK = L.common.processFailed;
 
 interface MemberDetailDrawerProps {
   user: TUserListItem;
@@ -178,11 +179,15 @@ const MemberDetailDrawer = ({
     setResending(true);
     try {
       await onResendCode();
-      showNotice("초대 코드 재전송", "초대 코드를 재전송했습니다.", "info");
+      showNotice(
+        BTN_TEXT.resendInvitationCode,
+        L.members.inviteCodeResent,
+        "info",
+      );
     } catch {
       showNotice(
-        "초대 코드 재전송",
-        "초대 코드 재전송에 실패했습니다. 다시 시도해 주세요.",
+        BTN_TEXT.resendInvitationCode,
+        L.members.resendCodeFailed,
         "error",
       );
     } finally {
@@ -222,15 +227,15 @@ const MemberDetailDrawer = ({
           checked: false,
         },
       ]);
-      showNotice("팀 추가", "팀에 추가되었습니다.", "info");
+      showNotice(L.members.addTeamTitle, L.members.addedToTeam, "info");
       resetAdd();
     } catch (err) {
       const code = err instanceof Response ? await parseErrorCode(err) : "";
       showNotice(
-        "팀 추가",
+        L.members.addTeamTitle,
         code === "ALREADY_TEAM_MEMBER"
-          ? "이미 소속된 팀입니다."
-          : "팀 추가에 실패했습니다. 다시 시도해 주세요.",
+          ? L.members.alreadyTeamMember
+          : L.members.addTeamFailed,
         "error",
       );
     } finally {
@@ -295,7 +300,9 @@ const MemberDetailDrawer = ({
 
         <section className="flex flex-col gap-4">
           <div className={styles.sectionHead}>
-            <b className="text-md">소속 팀 ({memberships.length})</b>
+            <b className="text-md">
+              {L.members.teamsHeading(memberships.length)}
+            </b>
             {selected.length > 0 && (
               <span className={styles.selectedCount}>
                 {selected.length} selected
@@ -313,11 +320,13 @@ const MemberDetailDrawer = ({
                       prev.map((m) => ({ ...m, checked })),
                     )
                   }
-                  ariaLabel="전체선택"
+                  ariaLabel={L.members.selectAll}
                 />
               </TableHeaderCell>
-              <TableHeaderCell>팀</TableHeaderCell>
-              <TableHeaderCell className="w-[104px]">권한</TableHeaderCell>
+              <TableHeaderCell>{L.common.team}</TableHeaderCell>
+              <TableHeaderCell className="w-[104px]">
+                {L.common.role}
+              </TableHeaderCell>
             </TableHead>
             <tbody>
               {memberships.length === 0 ? (
@@ -396,22 +405,24 @@ const MemberDetailDrawer = ({
               <Dropdown
                 options={addableTeams}
                 placeholder={
-                  addableTeams.length === 0 ? "추가할 팀 없음" : "팀 선택"
+                  addableTeams.length === 0
+                    ? L.members.noTeamsToAdd
+                    : L.members.selectTeam
                 }
                 value={addTeamId}
                 onChange={setAddTeamId}
                 size="sm"
-                ariaLabel="추가할 팀"
+                ariaLabel={L.members.teamToAdd}
                 className="flex-1"
                 disabled={addableTeams.length === 0}
               />
               <Dropdown
                 options={ROLE_OPTIONS}
-                placeholder="권한 선택"
+                placeholder={L.members.selectRole}
                 value={addRole}
                 onChange={setAddRole}
                 size="sm"
-                ariaLabel="추가할 role"
+                ariaLabel={L.members.roleToAdd}
                 className="w-24"
                 /* No team left to join (all already joined) → the role
                    picker has nothing to apply to, so disable it too. */
@@ -433,7 +444,7 @@ const MemberDetailDrawer = ({
 
         <section className="flex flex-col gap-4">
           <div className={styles.sectionHead}>
-            <b className="text-md">멤버 관리</b>
+            <b className="text-md">{L.nav.users}</b>
           </div>
 
           {/* Account-level actions: 세션 비활성화 · 멤버 삭제 (SC-15) —
@@ -464,7 +475,7 @@ const MemberDetailDrawer = ({
 
       {openModal === "role-confirm" && (
         <RoleChangeConfirmModal
-          subjectLabel="팀"
+          subjectLabel={L.common.team}
           changes={changes.map((m) => ({
             label: m.teamName,
             from: m.baseRole,
@@ -520,7 +531,7 @@ const MemberDetailDrawer = ({
             if (result.failed.length === 0) {
               showNotice(
                 MODAL_TITLES.removeMembership,
-                "멤버십이 제거되었습니다.",
+                L.teams.membershipsRemoved,
                 "success",
               );
             } else {
@@ -561,16 +572,20 @@ const MemberDetailDrawer = ({
             try {
               await onDeactivateSession();
               setOpenModal(null);
-              showNotice("세션 비활성화", "세션을 비활성화했습니다.", "info");
+              showNotice(
+                MODAL_TITLES.deactivateSession,
+                L.members.sessionDeactivated,
+                "info",
+              );
             } catch (err) {
               const code =
                 err instanceof Response ? await parseErrorCode(err) : "";
               setOpenModal(null);
               showNotice(
-                "세션 비활성화",
+                MODAL_TITLES.deactivateSession,
                 code === "SESSION_NOT_ACTIVE"
-                  ? "이미 만료된 세션입니다."
-                  : "세션 비활성화에 실패했습니다. 다시 시도해 주세요.",
+                  ? L.members.sessionAlreadyExpired
+                  : L.members.deactivateFailed,
                 "error",
               );
             }
@@ -586,16 +601,20 @@ const MemberDetailDrawer = ({
             try {
               await onCancelInvitation();
               setOpenModal(null);
-              showNotice("초대 취소", "초대를 취소했습니다.", "info");
+              showNotice(
+                MODAL_TITLES.cancelInvitation,
+                L.members.invitationCanceled,
+                "info",
+              );
             } catch (err) {
               const code =
                 err instanceof Response ? await parseErrorCode(err) : "";
               setOpenModal(null);
               showNotice(
-                "초대 취소",
+                MODAL_TITLES.cancelInvitation,
                 code === "INVITATION_NOT_PENDING"
-                  ? "취소할 초대가 없습니다."
-                  : "초대 취소에 실패했습니다. 다시 시도해 주세요.",
+                  ? L.members.noInvitationToCancel
+                  : L.members.cancelInvitationFailed,
                 "error",
               );
             }
diff --git a/frontend/src/components/users/MembershipRemoveModal.tsx b/frontend/src/components/users/MembershipRemoveModal.tsx
index 91925ed..2e104ba 100644
--- a/frontend/src/components/users/MembershipRemoveModal.tsx
+++ b/frontend/src/components/users/MembershipRemoveModal.tsx
@@ -5,9 +5,10 @@ import Notice from "@/components/elements/Notice";
 import ModalLayout from "@/components/layout/ModalLayout";
 import ModalTable from "@/components/users/ModalTable";
 import { BTN_TEXT, MODAL_TITLES } from "@/constants/commonConstants";
+import { L } from "@/locales";
 import type { TMembershipRemoveTarget } from "@/types/userTypes";
 
-const REMOVE_FAILED_MESSAGE = `멤버십 제거에 실패했습니다. 다시 시도해 주세요.`;
+const REMOVE_FAILED_MESSAGE = L.members.removeFailed;
 
 interface MembershipRemoveModalProps {
   /** SC-06 entry: selected members × current team · SC-13 entry:
@@ -67,9 +68,9 @@ const MembershipRemoveModal = ({
   return (
     <ModalLayout title={MODAL_TITLES.removeMembership} isOpen>
       <div className="flex flex-col gap-4">
-        <p className="text-base">다음 멤버십을 제거합니다:</p>
+        <p className="text-base">{L.teams.removeIntro}</p>
         <ModalTable
-          head={["account", "팀", "권한"]}
+          head={["account", L.common.team, L.common.role]}
           rows={targets.map((target) => [
             target.account,
             target.teamName,
@@ -77,9 +78,7 @@ const MembershipRemoveModal = ({
           ])}
         />
         {subteamNotice && (
-          <Notice>
-            하위 팀 소속은 유지됩니다. 필요할 경우 개별 선택 후 제거하세요.
-          </Notice>
+          <Notice>{L.teams.removeKeepSubteams}</Notice>
         )}
       </div>
       <div className="flex w-full items-center gap-4">
diff --git a/frontend/src/components/users/RoleChangeConfirmModal.tsx b/frontend/src/components/users/RoleChangeConfirmModal.tsx
index c724166..02e149d 100644
--- a/frontend/src/components/users/RoleChangeConfirmModal.tsx
+++ b/frontend/src/components/users/RoleChangeConfirmModal.tsx
@@ -5,10 +5,11 @@ import Notice from "@/components/elements/Notice";
 import ModalLayout from "@/components/layout/ModalLayout";
 import ModalTable from "@/components/users/ModalTable";
 import { BTN_TEXT, MODAL_TITLES } from "@/constants/commonConstants";
+import { L } from "@/locales";
 import type { TRoleChange } from "@/types/userTypes";
 
-const UPDATE_FAILED_MESSAGE = "권한 변경에 실패했습니다. 다시 시도해 주세요.";
-const UPDATE_SUCCESS_MESSAGE = "권한이 변경되었습니다.";
+const UPDATE_FAILED_MESSAGE = L.members.roleChangeFailedRetry;
+const UPDATE_SUCCESS_MESSAGE = L.members.roleChanged;
 
 type TPhase = "confirm" | "success" | "failed";
 
@@ -61,9 +62,9 @@ const RoleChangeConfirmModal = ({
   return (
     <ModalLayout title={MODAL_TITLES.roleChange} isOpen>
       <div className="flex flex-col gap-4">
-        <p className="text-base">다음 멤버의 권한을 변경합니다:</p>
+        <p className="text-base">{L.teams.roleChangeIntro}</p>
         <ModalTable
-          head={[subjectLabel, "권한"]}
+          head={[subjectLabel, L.common.role]}
           rows={rows.map((change) => [
             change.label,
             <>
diff --git a/frontend/src/components/users/SessionDeactivateModal.tsx b/frontend/src/components/users/SessionDeactivateModal.tsx
index f3e31b5..8a1a14c 100644
--- a/frontend/src/components/users/SessionDeactivateModal.tsx
+++ b/frontend/src/components/users/SessionDeactivateModal.tsx
@@ -3,6 +3,7 @@ import { useState } from "react";
 import Button from "@/components/elements/Button";
 import ModalLayout from "@/components/layout/ModalLayout";
 import { BTN_TEXT, MODAL_TITLES } from "@/constants/commonConstants";
+import { L } from "@/locales";
 
 interface SessionDeactivateModalProps {
   account: string;
@@ -37,8 +38,8 @@ const SessionDeactivateModal = ({
   return (
     <ModalLayout title={MODAL_TITLES.deactivateSession} isOpen>
       <p className="text-center text-base">
-        {account}의 세션을 비활성화하시겠습니까? <br />
-        모든 MCP 세션이 종료됩니다.
+        {L.members.deactivateConfirm(account)} <br />
+        {L.members.allMcpTerminated}
       </p>
       <div className="flex w-full items-center gap-4">
         <Button
diff --git a/frontend/src/components/users/invitePreview.ts b/frontend/src/components/users/invitePreview.ts
index 65e4027..3c697aa 100644
--- a/frontend/src/components/users/invitePreview.ts
+++ b/frontend/src/components/users/invitePreview.ts
@@ -2,6 +2,7 @@ import {
   getTeamDescendantIds,
   getTeamName,
 } from "@/components/teams/teamHierarchy";
+import { L } from "@/locales";
 import type { TTeamTree } from "@/types/teamTypes";
 import type { TInviteSet } from "@/types/userTypes";
 
@@ -39,7 +40,7 @@ export const buildInvitePreview = (
       teamId: set.teamId,
       teamName: getTeamName(teams, set.teamId),
       role: set.role,
-      reason: "직접 지정",
+      reason: L.members.directlyAssigned,
       indent: false,
     });
     for (const descId of getTeamDescendantIds(teams, set.teamId)) {
@@ -51,8 +52,8 @@ export const buildInvitePreview = (
         teamName: getTeamName(teams, descId),
         role: direct ?? set.role,
         reason: direct
-          ? "이미 초대된 팀입니다."
-          : `${getTeamName(teams, set.teamId)} 하위 팀`,
+          ? L.members.teamAlreadyInvited
+          : L.members.subteamOf(getTeamName(teams, set.teamId)),
         indent: true,
       });
     }
diff --git a/frontend/src/components/workspace/WorkspaceModal.tsx b/frontend/src/components/workspace/WorkspaceModal.tsx
index 13c47f9..e3046a3 100644
--- a/frontend/src/components/workspace/WorkspaceModal.tsx
+++ b/frontend/src/components/workspace/WorkspaceModal.tsx
@@ -22,13 +22,9 @@ import {
   PATH_LIST,
   WORKSPACE_MAX_MEMORIES,
 } from "@/constants/commonConstants";
+import { L } from "@/locales";
 import { useWorkspaceStore } from "@/stores/workspaceStore";
 
-const FAIL_COPY = {
-  stop: "워크스페이스 중지에 실패했습니다. 다시 시도해 주세요.",
-  restart: "워크스페이스 재실행에 실패했습니다. 다시 시도해 주세요.",
-} as const;
-
 const styles = {
   field: "flex items-center justify-between gap-4",
   label: "text-muted-foreground text-md",
@@ -91,7 +87,7 @@ const WorkspaceModal = () => {
     return (
       <ModalLayout title={MODAL_TITLES.workspaceOrphaned} isOpen>
         <p className="text-negative text-center text-base">
-          워크스페이스 재생성에 실패했습니다. 다시 시도해 주세요.
+          {L.workspace.recreateFailed}
         </p>
         {closeButton}
       </ModalLayout>
@@ -104,7 +100,7 @@ const WorkspaceModal = () => {
       return (
         <ModalLayout title={MODAL_TITLES.workspaceDelete} isOpen>
           <p className="text-negative text-center text-base">
-            워크스페이스 삭제에 실패했습니다. 다시 시도해 주세요.
+            {L.workspace.deleteFailed}
           </p>
           {closeButton}
         </ModalLayout>
@@ -113,9 +109,9 @@ const WorkspaceModal = () => {
     return (
       <ModalLayout title={MODAL_TITLES.workspaceDelete} isOpen>
         <p className="text-center text-base">
-          워크스페이스를 삭제하시겠습니까?
+          {L.workspace.deleteConfirm}
           <br />
-          삭제 후에는 되돌릴 수 없습니다.
+          {L.workspace.deleteIrreversible}
         </p>
         <div className="flex w-full gap-2">
           <Button
@@ -156,17 +152,17 @@ const WorkspaceModal = () => {
       <ModalLayout title={MODAL_TITLES.workspaceOrphaned} isOpen>
         {tearingDown ? (
           <p className="text-center text-base">
-            기존 워크스페이스를 삭제하는 중입니다…
+            {L.workspace.tearingDown1}
             <br />
-            삭제가 완료되면 워크스페이스 생성을 시작합니다.
+            {L.workspace.tearingDown2}
           </p>
         ) : (
           <p className="text-center text-base">
-            콘솔이 재설치되어 이 워크스페이스와 연결할 수 없습니다.
+            {L.workspace.orphaned1}
             <br />
-            기존에 저장된 데이터는 이전 보안 키로 암호화되어 복구할 수 없습니다.
+            {L.workspace.orphaned2}
             <br />
-            삭제 후 재생성하면 빈 워크스페이스로 다시 시작합니다.
+            {L.workspace.orphaned3}
           </p>
         )}
         <div className="flex w-full gap-2">
@@ -205,12 +201,12 @@ const WorkspaceModal = () => {
     return (
       <ModalLayout title={MODAL_TITLES.workspaceReconnect} isOpen>
         <p className="text-center text-base">
-          워크스페이스 연결이 만료되었습니다.
+          {L.workspace.reconnectExpired}
           <br />
-          재연결하여 데이터 플레인을 다시 활성화해 주세요.
+          {L.workspace.reconnectPrompt}
         </p>
         {reconnectMutation.isError && (
-          <Notice tone="error">재연결에 실패했습니다. 다시 시도해 주세요.</Notice>
+          <Notice tone="error">{L.workspace.reconnectFailed}</Notice>
         )}
         <div className="flex w-full gap-2">
           <Button
@@ -239,9 +235,9 @@ const WorkspaceModal = () => {
     return (
       <ModalLayout title={MODAL_TITLES.workspaceManage} isOpen>
         <p className="text-center text-base">
-          워크스페이스 정보를 불러올 수 없습니다.
+          {L.workspace.loadFailed}
           <br />
-          잠시 후 다시 시도해 주세요.
+          {L.common.tryAgainLater}
         </p>
         {closeButton}
       </ModalLayout>
@@ -249,9 +245,9 @@ const WorkspaceModal = () => {
   }
 
   const actionError = stopMutation.isError
-    ? FAIL_COPY.stop
+    ? L.workspace.stopFailed
     : startMutation.isError
-      ? FAIL_COPY.restart
+      ? L.workspace.restartFailed
       : null;
 
   return (
@@ -286,15 +282,15 @@ const WorkspaceModal = () => {
         </div>
 
         <div className={styles.field}>
-          <span className={styles.label}>플랜</span>
+          <span className={styles.label}>{L.workspace.plan}</span>
           <span className={styles.label}>Free</span>
         </div>
         <div className={styles.field}>
-          <span className={styles.label}>상태</span>
+          <span className={styles.label}>{L.workspace.statusLabel}</span>
           <WorkspaceStatus status={status} className="cursor-default" />
         </div>
         <div className={styles.field}>
-          <span className={styles.label}>저장된 기억 개수</span>
+          <span className={styles.label}>{L.workspace.storedMemories}</span>
           <span className={styles.value}>
             {workspace?.rowCount != null
               ? memoryUsage(workspace.rowCount)
diff --git a/frontend/src/constants/commonConstants.ts b/frontend/src/constants/commonConstants.ts
index d5bc00f..9e65d06 100644
--- a/frontend/src/constants/commonConstants.ts
+++ b/frontend/src/constants/commonConstants.ts
@@ -1,6 +1,8 @@
+import { L } from "@/locales";
+
 /** BRAND_WORDMARK is the displayed product wordmark, shared by the navbars
  * (SC-01/SC-03) and the login card heading (SC-01) so the brand string has a
- * single source of truth. */
+ * single source of truth. Deliberately not localized. */
 export const BRAND_WORDMARK = "RUNE CONSOLE";
 
 /** WORKSPACE_MAX_MEMORIES is the plan cap on stored memories (rows) per
@@ -8,82 +10,16 @@ export const BRAND_WORDMARK = "RUNE CONSOLE";
 export const WORKSPACE_MAX_MEMORIES = 1000;
 
 /** BTN_TEXT is the single source of truth for visible action-button labels
- * (Button `btnText` / TextButton) across the console screens, so a wording
- * change lands in one place. Icon-button aria-labels are intentionally out of
- * scope — those are accessibility strings, not button captions. */
-export const BTN_TEXT = {
-  // Generic actions
-  close: "닫기",
-  cancel: "취소",
-  confirm: "확인",
-  save: "저장",
-  delete: "삭제하기",
-  remove: "제거하기",
-  add: "추가",
-  create: "생성",
-  change: "변경하기",
-  refresh: "새로고침",
-  retry: "다시 시도",
-  update: "업데이트",
-  later: "나중에",
-  // Auth / navigation
-  signOut: "로그아웃",
-  getStarted: "시작하기",
-  login: "로그인하기",
-  home: "홈으로",
-  // Workspace
-  restart: "재실행",
-  stop: "중지",
-  deactivate: "비활성화",
-  recreate: "삭제 후 재생성",
-  reconnect: "재연결",
-  // Teams
-  createTeam: "새 팀 만들기",
-  createGroup: "팀 생성하기",
-  rename: "이름 변경",
-  deleteTeam: "팀 삭제하기",
-  addMember: "멤버 추가하기",
-  addTeam: "팀 추가하기",
-  // Members / invitations
-  invite: "초대하기",
-  inviteMember: "멤버 초대하기",
-  sendInvitation: "초대 전송",
-  resendInvitationCode: "초대 코드 재전송",
-  cancelInvitation: "초대 취소",
-  cancelAction: "취소하기",
-  addTeamRole: "+ 팀/권한 추가",
-  removeRow: "✕",
-  updateChanges: "변경사항 업데이트",
-  resetChanges: "변경사항 초기화",
-  deactivateSession: "세션 비활성화",
-  deleteMember: "멤버 삭제",
-} as const;
+ * (Button `btnText` / TextButton) across the console screens — the wording
+ * itself lives in src/locales (en.ts / ko.ts, chosen once at page load).
+ * Icon-button aria-labels are intentionally out of scope — those are
+ * accessibility strings, not button captions. */
+export const BTN_TEXT = L.btn;
 
 /** MODAL_TITLES is the single source of truth for ModalLayout titles across
- * the console modals, mirroring BTN_TEXT so a wording change lands in one
- * place. Titles that embed a name or count are functions; the rest are plain
- * strings. */
-export const MODAL_TITLES = {
-  // Workspace
-  workspaceManage: "워크스페이스 관리",
-  workspaceDelete: "워크스페이스 삭제",
-  workspaceOrphaned: "워크스페이스 재생성 필요",
-  workspaceReconnect: "워크스페이스 재연결 필요",
-  // Teams
-  createTeam: "새 팀 만들기",
-  renameTeam: "팀 이름 변경",
-  deleteTeam: (teamName: string) => `팀 삭제 — ${teamName}`,
-  addMember: (teamName: string) => `멤버 추가 — ${teamName}`,
-  batchFailure: "일부 항목을 처리하지 못했습니다",
-  // Members / roles / invitations
-  roleChange: "권한 변경",
-  removeMembership: "멤버십 제거",
-  inviteMember: "멤버 초대",
-  cancelInvitation: "초대 취소",
-  deactivateSession: "세션 비활성화",
-  deleteMemberSingle: (account: string) => `멤버 삭제 — ${account}`,
-  deleteMemberBulk: (count: number) => `멤버 삭제 (${count}명)`,
-} as const;
+ * the console modals, mirroring BTN_TEXT (wording in src/locales). Titles
+ * that embed a name or count are functions; the rest are plain strings. */
+export const MODAL_TITLES = L.modal;
 
 export const PATH_LIST = {
   home: "/",
@@ -96,9 +32,9 @@ export const PATH_LIST = {
 } as const;
 
 export const NAV_LIST = [
-  { title: "팀 관리", url: PATH_LIST.teams },
-  { title: "멤버 관리", url: PATH_LIST.users },
-  { title: "세션 기록", url: PATH_LIST.sessions },
+  { title: L.nav.teams, url: PATH_LIST.teams },
+  { title: L.nav.users, url: PATH_LIST.users },
+  { title: L.nav.sessions, url: PATH_LIST.sessions },
 ] as const;
 
 export const QUERY_KEYS = {
diff --git a/frontend/src/constants/styleConstants.ts b/frontend/src/constants/styleConstants.ts
index fad01a1..72aaffe 100644
--- a/frontend/src/constants/styleConstants.ts
+++ b/frontend/src/constants/styleConstants.ts
@@ -3,6 +3,7 @@
  * Visual values are translated from UIKIT modules/rune-ui-buttons and
  * modules/rune-admin-kit CSS — UIKIT is the design source of truth.
  */
+import { L } from "@/locales";
 
 /* Form controls embed w-full: the parent container constrains width.
    Metrics are UIKIT values normalized to even px (project rule). */
@@ -79,25 +80,31 @@ export const BADGE_TONE_VAR = {
   neutral: "bg-muted-foreground/12 text-muted-foreground",
 } as const;
 
+/* Status labels come from the locale table (src/locales, chosen once at page
+   load); colors are style concerns and stay here. */
+
 /* Session chips — the only status a list view shows. */
 export const MEMBER_STATUS_VAR = {
-  online: { label: "온라인", color: "text-mint" },
-  offline: { label: "오프라인", color: "text-faint" },
+  online: { label: L.status.member.online, color: "text-mint" },
+  offline: { label: L.status.member.offline, color: "text-faint" },
 } as const;
 
 /* Invitation-status labels — shown only in the member detail drawer. */
 export const INVITATION_STATUS_VAR = {
-  invite_pending: { label: "초대 수락 대기", color: "text-warning" },
-  invite_expired: { label: "초대 코드 만료", color: "text-faint" },
-  invite_redeemed: { label: "초대 코드 사용됨", color: "text-accent-blue" },
+  invite_pending: { label: L.status.invitation.pending, color: "text-warning" },
+  invite_expired: { label: L.status.invitation.expired, color: "text-faint" },
+  invite_redeemed: {
+    label: L.status.invitation.redeemed,
+    color: "text-accent-blue",
+  },
 } as const;
 
 export const WORKSPACE_STATUS_VAR = {
-  provisioning: { label: "생성 중", color: "text-warning" },
-  running: { label: "실행 중", color: "text-mint" },
-  stopping: { label: "정지 중", color: "text-warning" },
-  stopped: { label: "정지", color: "text-faint" },
-  starting: { label: "재실행 중", color: "text-warning" },
-  deleting: { label: "삭제 중", color: "text-warning" },
-  error: { label: "사용 불가", color: "text-negative" },
+  provisioning: { label: L.status.workspace.provisioning, color: "text-warning" },
+  running: { label: L.status.workspace.running, color: "text-mint" },
+  stopping: { label: L.status.workspace.stopping, color: "text-warning" },
+  stopped: { label: L.status.workspace.stopped, color: "text-faint" },
+  starting: { label: L.status.workspace.starting, color: "text-warning" },
+  deleting: { label: L.status.workspace.deleting, color: "text-warning" },
+  error: { label: L.status.workspace.error, color: "text-negative" },
 } as const;
diff --git a/frontend/src/locales/__tests__/locales.test.ts b/frontend/src/locales/__tests__/locales.test.ts
new file mode 100644
index 0000000..7157771
--- /dev/null
+++ b/frontend/src/locales/__tests__/locales.test.ts
@@ -0,0 +1,49 @@
+import { describe, expect, it } from "vitest";
+
+import { L, language } from "@/locales";
+import { en } from "@/locales/en";
+import { ko } from "@/locales/ko";
+import {
+  BTN_TEXT,
+  MODAL_TITLES,
+  NAV_LIST,
+} from "@/constants/commonConstants";
+import { WORKSPACE_STATUS_VAR } from "@/constants/styleConstants";
+
+/* Key parity between en and ko is enforced at COMPILE time (ko is typed as
+ * TLocale = typeof en), so a drifted key never survives tsc. The runtime
+ * checks here cover what types can't: the actual copy and interpolation. */
+
+describe("locales", () => {
+  it("resolves Korean under the test pin (setup.ts sets rc_lang=ko)", () => {
+    expect(language).toBe("ko");
+    expect(L).toBe(ko);
+    expect(BTN_TEXT.close).toBe("닫기");
+    expect(MODAL_TITLES.deleteTeam("platform")).toBe("팀 삭제 — platform");
+    expect(MODAL_TITLES.deleteMemberBulk(3)).toBe("멤버 삭제 (3명)");
+    expect(NAV_LIST[0].title).toBe("팀 관리");
+    expect(WORKSPACE_STATUS_VAR.running.label).toBe("실행 중");
+  });
+
+  it("carries the English copy with its own word order", () => {
+    expect(en.btn.close).toBe("Close");
+    expect(en.btn.resendInvitationCode).toBe("Resend Invitation Code");
+    expect(en.modal.deleteTeam("platform")).toBe("Delete Team — platform");
+    expect(en.modal.deleteMemberBulk(3)).toBe("Delete Members (3)");
+    expect(en.nav.teams).toBe("Team Management");
+    expect(en.status.workspace.running).toBe("Running");
+    expect(en.status.invitation.pending).toBe("Invitation Pending");
+  });
+
+  it("keeps both locales structurally identical at runtime too", () => {
+    const shape = (obj: object, prefix = ""): string[] =>
+      Object.entries(obj)
+        .flatMap(([k, v]) =>
+          typeof v === "object" && v !== null
+            ? shape(v, `${prefix}${k}.`)
+            : [`${prefix}${k}:${typeof v}`],
+        )
+        .sort();
+    expect(shape(en)).toEqual(shape(ko));
+  });
+});
diff --git a/frontend/src/locales/en.ts b/frontend/src/locales/en.ts
new file mode 100644
index 0000000..7fb6e6b
--- /dev/null
+++ b/frontend/src/locales/en.ts
@@ -0,0 +1,386 @@
+/**
+ * English UI copy. This module is the locale SHAPE's source of truth: ko.ts
+ * must satisfy TLocale, so a key added or removed here is a compile error
+ * there — the two languages cannot drift apart silently.
+ *
+ * Strings that embed a value are plain functions, so each language controls
+ * its own word order (Korean particles and counters don't map 1:1 to English).
+ */
+export const en = {
+  btn: {
+    // Generic actions
+    close: "Close",
+    cancel: "Cancel",
+    confirm: "Confirm",
+    save: "Save",
+    delete: "Delete",
+    remove: "Remove",
+    add: "Add",
+    create: "Create",
+    change: "Change",
+    refresh: "Refresh",
+    retry: "Retry",
+    update: "Update",
+    later: "Later",
+    // Auth / navigation
+    signOut: "Sign Out",
+    getStarted: "Get Started",
+    login: "Log In",
+    home: "Go to Home",
+    // Workspace
+    restart: "Restart",
+    stop: "Stop",
+    deactivate: "Deactivate",
+    recreate: "Delete and Recreate",
+    reconnect: "Reconnect",
+    // Teams
+    createTeam: "Create New Team",
+    createGroup: "Create Team",
+    rename: "Rename",
+    deleteTeam: "Delete Team",
+    addMember: "Add Member",
+    addTeam: "Add Team",
+    // Members / invitations
+    invite: "Invite",
+    inviteMember: "Invite Member",
+    sendInvitation: "Send Invitation",
+    resendInvitationCode: "Resend Invitation Code",
+    cancelInvitation: "Cancel Invitation",
+    cancelAction: "Cancel",
+    addTeamRole: "+ Add Team/Role",
+    removeRow: "✕",
+    updateChanges: "Update Changes",
+    resetChanges: "Reset Changes",
+    deactivateSession: "Deactivate Session",
+    deleteMember: "Delete Member",
+  },
+  modal: {
+    // Workspace
+    workspaceManage: "Manage Workspace",
+    workspaceDelete: "Delete Workspace",
+    workspaceOrphaned: "Workspace Recreation Required",
+    workspaceReconnect: "Workspace Reconnection Required",
+    // Teams
+    createTeam: "Create New Team",
+    renameTeam: "Rename Team",
+    deleteTeam: (teamName: string) => `Delete Team — ${teamName}`,
+    addMember: (teamName: string) => `Add Member — ${teamName}`,
+    batchFailure: "Some items could not be processed",
+    // Members / roles / invitations
+    roleChange: "Change Role",
+    removeMembership: "Remove Membership",
+    inviteMember: "Invite Member",
+    cancelInvitation: "Cancel Invitation",
+    deactivateSession: "Deactivate Session",
+    deleteMemberSingle: (account: string) => `Delete Member — ${account}`,
+    deleteMemberBulk: (count: number) => `Delete Members (${count})`,
+  },
+  nav: {
+    teams: "Team Management",
+    users: "Member Management",
+    sessions: "Session History",
+  },
+  login: {
+    failed1: "There was a problem signing in.",
+    failed2: "Please try again.",
+    accountRequired: "A RUNE account is required to use the console.",
+  },
+  status: {
+    member: {
+      online: "Online",
+      offline: "Offline",
+    },
+    invitation: {
+      pending: "Invitation Pending",
+      expired: "Invitation Code Expired",
+      redeemed: "Invitation Code Used",
+    },
+    workspace: {
+      provisioning: "Creating",
+      running: "Running",
+      stopping: "Stopping",
+      stopped: "Stopped",
+      starting: "Restarting",
+      deleting: "Deleting",
+      error: "Unavailable",
+    },
+  },
+  profile: {
+    menu: "Profile menu",
+    image: "Profile image",
+    plan: "Plan: Free",
+  },
+  common: {
+    none: "None",
+    loading: "Loading…",
+    team: "Team",
+    role: "Role",
+    memberName: "Member Name",
+    memberStatus: "Member Status",
+    selectAll: "Select All",
+    select: "Select",
+    all: "All",
+    users: "Users",
+    sort: "Sort",
+    sortBy: "Sort by",
+    noResults: "No results found.",
+    refreshRetry: "Refresh and try again.",
+    tryAgainLater: "Please try again later.",
+    processFailed: "Processing failed. Please try again.",
+    selectName: (name: string) => `Select ${name}`,
+  },
+  elements: {
+    pagination: "Pagination",
+    prevPage: "Previous page",
+    nextPage: "Next page",
+    search: "Search",
+    clear: "Clear",
+    clickToDismiss: "Click to dismiss",
+    unsavedChanges: "Unsaved changes",
+  },
+  auth: {
+    ownerLockedTitle: "Account Not Available",
+    // Sentence split around the styled owner element: prefix + owner + suffix.
+    ownerLockedPrefix: "This console is managed by ",
+    ownerLockedSuffix: ".",
+    ownerFallback: "another account",
+    ownerLockedBody: "You can't use the console with this account.",
+  },
+  teams: {
+    // Add-member modal
+    emailLabel: "Email (account)",
+    invalidEmail: "Invalid email format.",
+    usernameLabel: "Username",
+    usernamePlaceholder: "Username",
+    roleLabel: "Role",
+    selectRole: "Select Role",
+    // Sentence split around the inline member-status chip: prefix + status + suffix.
+    invitePrefix:
+      "Once the invited user connects rune, their status changes to ",
+    inviteSuffix: ".",
+    // Team name / create / rename
+    teamNameRule: "Only numbers, Korean and English letters, - and _ are allowed.",
+    teamName: "Team Name",
+    teamNamePlaceholder: "e.g. platform-team",
+    parentTeamOptional: "Parent Team (Optional)",
+    selectTeam: "Select Team",
+    parentCopyInfo1:
+      "Selecting a parent team automatically copies its members to the new team.",
+    parentCopyInfo2:
+      "You can edit members on the detail page after the team is created.",
+    dupName: "A team with this name already exists under the same parent team.",
+    invalidTeamName: "Invalid team name format.",
+    // Delete-team modal
+    hasChildrenAlert1: "Teams with sub-teams cannot be deleted.",
+    hasChildrenAlert2: "Delete the sub-teams first, then try again.",
+    memoryChoiceInfo: "Choose how to handle this team's memory before deleting.",
+    transferOption: "① Transfer to Another Team",
+    defaultTag: "(Default)",
+    destinationTeam: "Destination Team",
+    confirmTargetLabel: "Confirm — Enter Target Team Name",
+    selectTeamFirst: "Select a team first",
+    targetNameMismatch: "Target team name does not match.",
+    purgeOption: "② Delete This Team's Memory",
+    purgeDesc:
+      "Memories shared with other teams will remain accessible from those teams.",
+    confirmDeleteLabel: "Confirm — Enter Team Name to Delete",
+    nameMismatch: "Team name does not match.",
+    cannotDeleteHasChildren: "Cannot delete a team that has sub-teams.",
+    // Org chart
+    viewDetails: (name: string) => `View ${name} details`,
+    zoomOut: "Zoom Out",
+    zoomIn: "Zoom In",
+    // Remove-membership / role-change modals
+    removeIntro: "The following memberships will be removed:",
+    removeKeepSubteams:
+      "Sub-team memberships are kept. Select them individually to remove if needed.",
+    roleChangeIntro: "The following members' roles will be changed:",
+    roleChangeCol: "Role Change",
+    // Tree & detail view
+    teamTree: "Team Tree",
+    teamMeta: (parent: string, children: string, count: number, date: string) =>
+      `Parent team: ${parent} | Sub-teams: ${children} | Members: ${count} | Created: ${date}`,
+    countItems: (count: number) => `${count}`,
+    membersHeading: (total: number) => `Members (${total})`,
+    memberPageInfo: (total: number, pageSize: number) =>
+      `${total} total · ${pageSize} per page`,
+    roleHeader: "Role",
+    joinedAt: "Joined",
+    membersLoadError: "Unable to load the member list.",
+    noMembers: "No members.",
+    changesSaved: "Changes saved.",
+    // Notices (team CRUD / member ops)
+    createTeamTitle: "Create Team",
+    teamCreated: "Team created.",
+    createTeamFailed: "Failed to create the team.",
+    teamRenamed: "Team name changed.",
+    renameFailed: "Failed to rename the team.",
+    deleteTeamTitle: "Delete Team",
+    teamDeleted: "Team deleted.",
+    deleteFailed: "Failed to delete the team.",
+    addMemberTitle: "Add Member",
+    memberAdded: "Member added.",
+    addMemberFailed: "Failed to add the member.",
+    roleChangeFailed: "Failed to change roles.",
+    membershipsRemoved: "Memberships removed.",
+    removeFailed: "Failed to remove memberships.",
+    // Server error reasons
+    userNotFound: "User not found",
+    notTeamMember: "Not a team member",
+    alreadyInvited: "This user has already been invited.",
+    notRegistered: "This account is not registered.",
+    cannotAddAdmin: "Console admin accounts cannot be added.",
+    inviteSendFailed: "Failed to send the invite code. Please try again.",
+    // Team tree / nodes
+    checkTeamName: "Check the team name and try again.",
+    collapseName: (name: string) => `Collapse ${name}`,
+    expandName: (name: string) => `Expand ${name}`,
+    // Teams page
+    switchView: "Switch view",
+    treeDetail: "Tree & Detail",
+    orgChartView: "Org Chart",
+    searchTeams: "Search teams",
+    teamsLoadError: "Couldn't load teams.",
+    emptyTitle: "Create your first team.",
+    emptyDesc: "Create a team to manage members and memory.",
+  },
+  members: {
+    // Invite modal (SC-12)
+    emailFormatError: "Please enter a valid email address",
+    duplicateAccount:
+      "This account is already registered. Use Add Member or Resend Invitation Code instead.",
+    sendFailed: "Failed to send invitation. Please try again.",
+    teamRole: "Team / Role",
+    selectTeam: "Select team",
+    selectRole: "Select role",
+    setTeamAria: (n: number) => `Set ${n} team`,
+    setRoleAria: (n: number) => `Set ${n} role`,
+    subteamPreview: "Sub-Team Role Preview",
+    reason: "Reason",
+    // Sentence split around the inline member-status chip: prefix + status + suffix.
+    invitePrefix:
+      "When invited, the user receives an invitation code; once they connect rune within 24 hours, their status changes to ",
+    inviteSuffix: ".",
+    inviteExpiry:
+      "If they do not connect, the code expires and you can invite them again with Resend Invitation Code.",
+    // Invite preview rows (invitePreview.ts)
+    directlyAssigned: "Directly assigned",
+    teamAlreadyInvited: "Team already invited.",
+    subteamOf: (teamName: string) => `Sub-team of ${teamName}`,
+    // Cancel-invitation modal (D15)
+    cancelInviteExpires: (account: string) =>
+      `All unused invitation codes for ${account} will expire.`,
+    userNotDeleted: "The user will not be deleted.",
+    // Session-deactivate modal (D12)
+    deactivateConfirm: (account: string) =>
+      `Deactivate the session for ${account}?`,
+    allMcpTerminated: "All MCP sessions will be terminated.",
+    // Member-delete modal (SC-15)
+    deleteFailed: "Failed to delete member. Please try again.",
+    noTeams: "Not a member of any team.",
+    deleteSingleIntro: (account: string) =>
+      `The account ${account} will be deleted and removed from the teams below:`,
+    deleteBulkIntro:
+      "The following members' accounts will be deleted and removed from the teams below:",
+    // Membership-remove / role-change modals
+    removeFailed: "Failed to remove membership. Please try again.",
+    roleChangeFailedRetry: "Failed to change role. Please try again.",
+    roleChanged: "Role changed.",
+    // Member-detail drawer (SC-13)
+    lastAccessed: (date: string) => `Last accessed ${date}`,
+    redeemedAwaiting: "Invitation code used · Awaiting connection",
+    lastInviteSentAt: (datetime: string) =>
+      `Last invitation code sent ${datetime}`,
+    teamNotFound: "Team not found",
+    inviteCodeResent: "Invitation code resent.",
+    resendCodeFailed: "Failed to resend invitation code. Please try again.",
+    addTeamTitle: "Add Team",
+    addedToTeam: "Added to team.",
+    alreadyTeamMember: "Already a member of this team.",
+    addTeamFailed: "Failed to add team. Please try again.",
+    teamsHeading: (count: number) => `Teams (${count})`,
+    selectAll: "Select all",
+    noTeamsToAdd: "No teams to add",
+    teamToAdd: "Team to add",
+    roleToAdd: "Role to add",
+    sessionDeactivated: "Session deactivated.",
+    sessionAlreadyExpired: "This session has already expired.",
+    deactivateFailed: "Failed to deactivate session. Please try again.",
+    invitationCanceled: "Invitation canceled.",
+    noInvitationToCancel: "No invitation to cancel.",
+    cancelInvitationFailed: "Failed to cancel invitation. Please try again.",
+    // Users page (SC-11)
+    lastInviteSent: "Last Invitation Code Sent",
+    resendFailedShort: "Resend failed",
+    deleteMembersTitle: "Delete Members",
+    membersDeleted: "Members deleted.",
+    membersLoadError: "Couldn't load members.",
+    noMembersYet: "No members invited yet",
+    inviteHint: "Invite a member and an invitation code will be sent by email",
+    searchByName: "Search by name",
+    statusFilterAria: "Status filter",
+    teamFilterAria: "Team filter",
+    teamRoleHeader: "Team (Role)",
+    // Sessions page (SC-16)
+    lastIssued: "Last Issued",
+    lastAccessedAt: "Last Accessed",
+    historyLoadError: "Couldn't load history.",
+    sessionPageInfo: (total: number, pageSize: number) =>
+      `${total} total · ${pageSize} per page`,
+    issuedAt: "Issued At",
+    noHistory: "No history.",
+  },
+  workspace: {
+    // Navbar badge (SC-03 callout 2)
+    badgeLabel: "Workspace",
+    badgeRecreate: "Recreation Required",
+    badgeReconnect: "Reconnection Required",
+    badgeNone: "No Workspace",
+    // Management modal (SC-02 state D + variants)
+    stopFailed: "Failed to stop workspace. Please try again.",
+    restartFailed: "Failed to restart workspace. Please try again.",
+    recreateFailed: "Failed to recreate workspace. Please try again.",
+    deleteFailed: "Failed to delete workspace. Please try again.",
+    deleteConfirm: "Delete this workspace?",
+    deleteIrreversible: "This action cannot be undone.",
+    tearingDown1: "Deleting the existing workspace…",
+    tearingDown2: "Workspace creation will start once deletion is complete.",
+    orphaned1:
+      "The console was reinstalled and can no longer connect to this workspace.",
+    orphaned2:
+      "Previously stored data is encrypted with the old security key and cannot be recovered.",
+    orphaned3: "Delete and recreate to start over with an empty workspace.",
+    reconnectExpired: "The workspace connection has expired.",
+    reconnectPrompt: "Reconnect to reactivate the data plane.",
+    reconnectFailed: "Failed to reconnect. Please try again.",
+    loadFailed: "Unable to load workspace information.",
+    plan: "Plan",
+    statusLabel: "Status",
+    storedMemories: "Stored Memories",
+    // Empty-workspace page (SC-02 states A/B/C)
+    pageAria: "Workspace management",
+    creatingTitle: "Creating your workspace…",
+    creatingDesc: "This takes about 3–5 minutes.",
+    createFailedTitle: "Workspace Creation Failed",
+    createFailedDesc: "Couldn't create the workspace. Please try again.",
+    createWorkspace: "Create Workspace",
+    emptyTitle: "No workspace has been created.",
+    emptyDesc: "Create a workspace to store memory.",
+    // Console update floating card
+    updatingTitle: "Updating the Console",
+    updateFailedTitle: "Update Failed",
+    newVersionTitle: "New Version Available",
+    updateRunning: "Backing up and updating…",
+    updatePreparing: "Preparing the update…",
+    updateFailedBody:
+      "The update could not be completed. Check the status and try again.",
+    updateRestartNotice:
+      "RUNE may be temporarily unavailable while the console restarts.",
+  },
+  validation: {
+    usernameRule:
+      "Only Korean, lowercase English letters, and single spaces between words are allowed.",
+  },
+};
+
+export type TLocale = typeof en;
diff --git a/frontend/src/locales/index.ts b/frontend/src/locales/index.ts
new file mode 100644
index 0000000..a3c95a5
--- /dev/null
+++ b/frontend/src/locales/index.ts
@@ -0,0 +1,37 @@
+import { en, type TLocale } from "./en";
+import { ko } from "./ko";
+
+/** LANG_STORAGE_KEY persists an explicit user language choice; absent, the
+ * browser language decides (Korean browsers → ko, everything else → en). */
+export const LANG_STORAGE_KEY = "rc_lang";
+
+export type TLanguage = "en" | "ko";
+
+const detectLanguage = (): TLanguage => {
+  try {
+    const stored = localStorage.getItem(LANG_STORAGE_KEY);
+    if (stored === "en" || stored === "ko") return stored;
+  } catch {
+    /* storage unavailable (private mode) — fall through to browser language */
+  }
+  return navigator.language?.toLowerCase().startsWith("ko") ? "ko" : "en";
+};
+
+/** language is resolved ONCE at page load and never changes within a visit —
+ * every string read below is a plain static property access. */
+export const language: TLanguage = detectLanguage();
+
+/** L is the active locale table. Import L and read L.btn.close etc.; the
+ * value is the same hardcoded string on every access for the whole visit. */
+export const L: TLocale = language === "ko" ? ko : en;
+
+/** setLanguage persists the choice and reloads — the locale is bound at page
+ * load (see above), so a reload is what applies the new language everywhere. */
+export const setLanguage = (lang: TLanguage) => {
+  try {
+    localStorage.setItem(LANG_STORAGE_KEY, lang);
+  } catch {
+    /* storage unavailable — reload alone keeps the browser-language default */
+  }
+  window.location.reload();
+};
diff --git a/frontend/src/locales/ko.ts b/frontend/src/locales/ko.ts
new file mode 100644
index 0000000..430c72b
--- /dev/null
+++ b/frontend/src/locales/ko.ts
@@ -0,0 +1,373 @@
+import type { TLocale } from "./en";
+
+/**
+ * Korean UI copy — the strings the console shipped with, verbatim. Typed as
+ * TLocale (derived from en.ts) so any key drift between the languages is a
+ * compile error.
+ */
+export const ko: TLocale = {
+  btn: {
+    // Generic actions
+    close: "닫기",
+    cancel: "취소",
+    confirm: "확인",
+    save: "저장",
+    delete: "삭제하기",
+    remove: "제거하기",
+    add: "추가",
+    create: "생성",
+    change: "변경하기",
+    refresh: "새로고침",
+    retry: "다시 시도",
+    update: "업데이트",
+    later: "나중에",
+    // Auth / navigation
+    signOut: "로그아웃",
+    getStarted: "시작하기",
+    login: "로그인하기",
+    home: "홈으로",
+    // Workspace
+    restart: "재실행",
+    stop: "중지",
+    deactivate: "비활성화",
+    recreate: "삭제 후 재생성",
+    reconnect: "재연결",
+    // Teams
+    createTeam: "새 팀 만들기",
+    createGroup: "팀 생성하기",
+    rename: "이름 변경",
+    deleteTeam: "팀 삭제하기",
+    addMember: "멤버 추가하기",
+    addTeam: "팀 추가하기",
+    // Members / invitations
+    invite: "초대하기",
+    inviteMember: "멤버 초대하기",
+    sendInvitation: "초대 전송",
+    resendInvitationCode: "초대 코드 재전송",
+    cancelInvitation: "초대 취소",
+    cancelAction: "취소하기",
+    addTeamRole: "+ 팀/권한 추가",
+    removeRow: "✕",
+    updateChanges: "변경사항 업데이트",
+    resetChanges: "변경사항 초기화",
+    deactivateSession: "세션 비활성화",
+    deleteMember: "멤버 삭제",
+  },
+  modal: {
+    // Workspace
+    workspaceManage: "워크스페이스 관리",
+    workspaceDelete: "워크스페이스 삭제",
+    workspaceOrphaned: "워크스페이스 재생성 필요",
+    workspaceReconnect: "워크스페이스 재연결 필요",
+    // Teams
+    createTeam: "새 팀 만들기",
+    renameTeam: "팀 이름 변경",
+    deleteTeam: (teamName: string) => `팀 삭제 — ${teamName}`,
+    addMember: (teamName: string) => `멤버 추가 — ${teamName}`,
+    batchFailure: "일부 항목을 처리하지 못했습니다",
+    // Members / roles / invitations
+    roleChange: "권한 변경",
+    removeMembership: "멤버십 제거",
+    inviteMember: "멤버 초대",
+    cancelInvitation: "초대 취소",
+    deactivateSession: "세션 비활성화",
+    deleteMemberSingle: (account: string) => `멤버 삭제 — ${account}`,
+    deleteMemberBulk: (count: number) => `멤버 삭제 (${count}명)`,
+  },
+  nav: {
+    teams: "팀 관리",
+    users: "멤버 관리",
+    sessions: "세션 기록",
+  },
+  login: {
+    failed1: "로그인 중 문제가 발생했습니다.",
+    failed2: "다시 시도해 주세요.",
+    accountRequired: "콘솔을 사용하기 위해 RUNE 계정이 필요합니다.",
+  },
+  status: {
+    member: {
+      online: "온라인",
+      offline: "오프라인",
+    },
+    invitation: {
+      pending: "초대 수락 대기",
+      expired: "초대 코드 만료",
+      redeemed: "초대 코드 사용됨",
+    },
+    workspace: {
+      provisioning: "생성 중",
+      running: "실행 중",
+      stopping: "정지 중",
+      stopped: "정지",
+      starting: "재실행 중",
+      deleting: "삭제 중",
+      error: "사용 불가",
+    },
+  },
+  profile: {
+    menu: "프로필 메뉴",
+    image: "프로필 이미지",
+    plan: "플랜: Free",
+  },
+  common: {
+    none: "없음",
+    loading: "불러오는 중…",
+    team: "팀",
+    role: "권한",
+    memberName: "멤버 이름",
+    memberStatus: "멤버 상태",
+    selectAll: "전체 선택",
+    select: "선택",
+    all: "전체",
+    users: "사용자",
+    sort: "정렬",
+    sortBy: "정렬 기준",
+    noResults: "검색 결과가 없습니다.",
+    refreshRetry: "새로고침 후 다시 시도해 주세요.",
+    tryAgainLater: "잠시 후 다시 시도해 주세요.",
+    processFailed: "처리에 실패했습니다. 다시 시도해 주세요.",
+    selectName: (name: string) => `${name} 선택`,
+  },
+  elements: {
+    pagination: "페이지네이션",
+    prevPage: "이전 페이지",
+    nextPage: "다음 페이지",
+    search: "검색",
+    clear: "지우기",
+    clickToDismiss: "클릭하여 닫기",
+    unsavedChanges: "변경사항 있음",
+  },
+  auth: {
+    ownerLockedTitle: "사용할 수 없는 계정",
+    // 소유자 강조 요소를 사이에 둔 문장 분할: prefix + owner + suffix.
+    ownerLockedPrefix: "이 콘솔은 ",
+    ownerLockedSuffix: "이(가) 관리하고 있어요.",
+    ownerFallback: "다른 계정",
+    ownerLockedBody: "이 계정으로는 콘솔을 사용할 수 없습니다.",
+  },
+  teams: {
+    // Add-member modal
+    emailLabel: "이메일 (account)",
+    invalidEmail: "올바른 이메일 형식이 아닙니다.",
+    usernameLabel: "사용자 이름 (username)",
+    usernamePlaceholder: "사용자 이름",
+    roleLabel: "권한 (role)",
+    selectRole: "권한 선택",
+    // 인라인 멤버 상태 칩을 사이에 둔 문장 분할: prefix + status + suffix.
+    invitePrefix: "초대받은 사용자가 rune을 연결하면 ",
+    inviteSuffix: "으로 전환됩니다.",
+    // Team name / create / rename
+    teamNameRule: "숫자·한글·영어와 - _ 만 사용할 수 있습니다.",
+    teamName: "팀 이름",
+    teamNamePlaceholder: "예: platform-team",
+    parentTeamOptional: "상위 팀 (선택)",
+    selectTeam: "팀 선택",
+    parentCopyInfo1: "상위 팀을 선택하면 상위 팀의 멤버가 새 팀에 자동 복사됩니다.",
+    parentCopyInfo2: "멤버 편집은 팀 생성 후 상세 페이지에서 할 수 있습니다.",
+    dupName: "같은 상위 팀에 동일한 이름이 이미 있습니다.",
+    invalidTeamName: "팀 이름 형식이 올바르지 않습니다.",
+    // Delete-team modal
+    hasChildrenAlert1: "하위 팀이 있는 팀은 삭제할 수 없습니다.",
+    hasChildrenAlert2: "하위 팀을 먼저 삭제한 후 다시 시도해 주세요.",
+    memoryChoiceInfo: "삭제하려는 팀의 기억 처리 방식을 선택해 주세요.",
+    transferOption: "① 다른 팀으로 이전",
+    defaultTag: "(기본값)",
+    destinationTeam: "이전받을 팀",
+    confirmTargetLabel: "확인 - 타겟 팀명 입력",
+    selectTeamFirst: "팀을 먼저 선택하세요",
+    targetNameMismatch: "타겟 팀명이 일치하지 않습니다.",
+    purgeOption: "② 팀 내 기억 삭제",
+    purgeDesc: "다른 팀과 공유 중인 기억은 해당 팀에서 계속 조회할 수 있습니다.",
+    confirmDeleteLabel: "확인 - 삭제할 팀명 입력",
+    nameMismatch: "팀명이 일치하지 않습니다.",
+    cannotDeleteHasChildren: "하위 팀이 있어 삭제할 수 없습니다.",
+    // Org chart
+    viewDetails: (name: string) => `${name} 상세 보기`,
+    zoomOut: "축소",
+    zoomIn: "확대",
+    // Remove-membership / role-change modals
+    removeIntro: "다음 멤버십을 제거합니다:",
+    removeKeepSubteams: "하위 팀 소속은 유지됩니다. 필요할 경우 개별 선택 후 제거하세요.",
+    roleChangeIntro: "다음 멤버의 권한을 변경합니다:",
+    roleChangeCol: "권한 변경",
+    // Tree & detail view
+    teamTree: "팀 트리",
+    teamMeta: (parent: string, children: string, count: number, date: string) =>
+      `상위 팀: ${parent} | 하위 팀: ${children} | 멤버: ${count}명 | 생성일: ${date}`,
+    countItems: (count: number) => `${count}개`,
+    membersHeading: (total: number) => `멤버 (${total})`,
+    memberPageInfo: (total: number, pageSize: number) =>
+      `총 ${total}명 · ${pageSize}명/페이지`,
+    roleHeader: "역할",
+    joinedAt: "합류일",
+    membersLoadError: "멤버 목록을 불러올 수 없습니다.",
+    noMembers: "멤버가 없습니다.",
+    changesSaved: "변경사항이 저장되었습니다.",
+    // Notices (team CRUD / member ops)
+    createTeamTitle: "팀 생성",
+    teamCreated: "팀이 생성되었습니다.",
+    createTeamFailed: "팀 생성에 실패했습니다.",
+    teamRenamed: "팀 이름이 변경되었습니다.",
+    renameFailed: "이름 변경에 실패했습니다.",
+    deleteTeamTitle: "팀 삭제",
+    teamDeleted: "팀이 삭제되었습니다.",
+    deleteFailed: "팀 삭제에 실패했습니다.",
+    addMemberTitle: "멤버 추가",
+    memberAdded: "멤버를 추가했습니다.",
+    addMemberFailed: "멤버 추가에 실패했습니다.",
+    roleChangeFailed: "권한 변경에 실패했습니다.",
+    membershipsRemoved: "멤버십이 제거되었습니다.",
+    removeFailed: "멤버십 제거에 실패했습니다.",
+    // Server error reasons
+    userNotFound: "사용자를 찾을 수 없습니다",
+    notTeamMember: "팀 멤버가 아닙니다",
+    alreadyInvited: "이미 초대된 사용자입니다.",
+    notRegistered: "등록되지 않은 계정입니다.",
+    cannotAddAdmin: "콘솔 관리자 계정은 추가할 수 없습니다.",
+    inviteSendFailed: "초대 코드 전송에 실패했습니다. 다시 시도해 주세요.",
+    // Team tree / nodes
+    checkTeamName: "팀 이름을 다시 확인해 주세요.",
+    collapseName: (name: string) => `${name} 접기`,
+    expandName: (name: string) => `${name} 펼치기`,
+    // Teams page
+    switchView: "보기 전환",
+    treeDetail: "트리·상세",
+    orgChartView: "조직도",
+    searchTeams: "팀 검색",
+    teamsLoadError: "팀 정보를 불러올 수 없습니다.",
+    emptyTitle: "새로운 팀을 만들어 주세요.",
+    emptyDesc: "팀을 생성하면 멤버와 기억(memory)을 관리할 수 있습니다.",
+  },
+  members: {
+    // Invite modal (SC-12)
+    emailFormatError: "올바른 이메일 형식이 아닙니다",
+    duplicateAccount:
+      "이미 등록된 계정입니다. 멤버 추가 또는 초대 코드 재전송을 사용하세요.",
+    sendFailed: "초대 전송에 실패했습니다. 다시 시도해 주세요.",
+    teamRole: "팀 / 권한",
+    selectTeam: "팀 선택",
+    selectRole: "권한 선택",
+    setTeamAria: (n: number) => `세트 ${n} 팀`,
+    setRoleAria: (n: number) => `세트 ${n} role`,
+    subteamPreview: "하위 팀 권한 미리보기",
+    reason: "사유",
+    // 인라인 멤버 상태 칩을 사이에 둔 문장 분할: prefix + status + suffix.
+    invitePrefix:
+      "초대 시 사용자에게 초대 코드가 발송되어 사용자가 24시간 내 rune을 연결하면 ",
+    inviteSuffix: " 으로 전환됩니다.",
+    inviteExpiry:
+      "미연결 시 코드가 만료되고 초대 코드 재전송으로 사용자를 다시 초대할 수 있습니다.",
+    // Invite preview rows (invitePreview.ts)
+    directlyAssigned: "직접 지정",
+    teamAlreadyInvited: "이미 초대된 팀입니다.",
+    subteamOf: (teamName: string) => `${teamName} 하위 팀`,
+    // Cancel-invitation modal (D15)
+    cancelInviteExpires: (account: string) =>
+      `${account}의 미사용 초대 코드가 모두 만료됩니다.`,
+    userNotDeleted: "유저는 삭제되지 않습니다.",
+    // Session-deactivate modal (D12)
+    deactivateConfirm: (account: string) =>
+      `${account}의 세션을 비활성화하시겠습니까?`,
+    allMcpTerminated: "모든 MCP 세션이 종료됩니다.",
+    // Member-delete modal (SC-15)
+    deleteFailed: "멤버 삭제에 실패했습니다. 다시 시도해 주세요.",
+    noTeams: "소속된 팀이 없습니다.",
+    deleteSingleIntro: (account: string) =>
+      `${account} 계정을 삭제하며, 아래 팀에서 제거됩니다:`,
+    deleteBulkIntro: "다음 멤버의 계정을 삭제하며, 아래 팀에서 제거됩니다:",
+    // Membership-remove / role-change modals
+    removeFailed: "멤버십 제거에 실패했습니다. 다시 시도해 주세요.",
+    roleChangeFailedRetry: "권한 변경에 실패했습니다. 다시 시도해 주세요.",
+    roleChanged: "권한이 변경되었습니다.",
+    // Member-detail drawer (SC-13)
+    lastAccessed: (date: string) => `최근 접속 ${date}`,
+    redeemedAwaiting: "초대 코드 사용됨 · 연결 대기 중",
+    lastInviteSentAt: (datetime: string) => `최근 초대 코드 발송 ${datetime}`,
+    teamNotFound: "팀을 찾을 수 없습니다",
+    inviteCodeResent: "초대 코드를 재전송했습니다.",
+    resendCodeFailed: "초대 코드 재전송에 실패했습니다. 다시 시도해 주세요.",
+    addTeamTitle: "팀 추가",
+    addedToTeam: "팀에 추가되었습니다.",
+    alreadyTeamMember: "이미 소속된 팀입니다.",
+    addTeamFailed: "팀 추가에 실패했습니다. 다시 시도해 주세요.",
+    teamsHeading: (count: number) => `소속 팀 (${count})`,
+    selectAll: "전체선택",
+    noTeamsToAdd: "추가할 팀 없음",
+    teamToAdd: "추가할 팀",
+    roleToAdd: "추가할 role",
+    sessionDeactivated: "세션을 비활성화했습니다.",
+    sessionAlreadyExpired: "이미 만료된 세션입니다.",
+    deactivateFailed: "세션 비활성화에 실패했습니다. 다시 시도해 주세요.",
+    invitationCanceled: "초대를 취소했습니다.",
+    noInvitationToCancel: "취소할 초대가 없습니다.",
+    cancelInvitationFailed: "초대 취소에 실패했습니다. 다시 시도해 주세요.",
+    // Users page (SC-11)
+    lastInviteSent: "최근 초대 코드 발송",
+    resendFailedShort: "재전송 실패",
+    deleteMembersTitle: "멤버 삭제",
+    membersDeleted: "멤버를 삭제했습니다.",
+    membersLoadError: "멤버 정보를 불러올 수 없습니다.",
+    noMembersYet: "아직 초대한 멤버가 없습니다",
+    inviteHint: "멤버를 초대하면 초대 코드가 이메일로 발송됩니다",
+    searchByName: "이름 검색",
+    statusFilterAria: "status 필터",
+    teamFilterAria: "group 필터",
+    teamRoleHeader: "팀 (권한)",
+    // Sessions page (SC-16)
+    lastIssued: "최근 발급 시간",
+    lastAccessedAt: "최근 접속 시간",
+    historyLoadError: "이력 정보를 불러올 수 없습니다.",
+    sessionPageInfo: (total: number, pageSize: number) =>
+      `총 ${total}건 · ${pageSize}건/페이지`,
+    issuedAt: "발급 시간",
+    noHistory: "이력이 없습니다.",
+  },
+  workspace: {
+    // Navbar badge (SC-03 callout 2)
+    badgeLabel: "워크스페이스",
+    badgeRecreate: "재생성 필요",
+    badgeReconnect: "재연결 필요",
+    badgeNone: "워크스페이스 없음",
+    // Management modal (SC-02 state D + variants)
+    stopFailed: "워크스페이스 중지에 실패했습니다. 다시 시도해 주세요.",
+    restartFailed: "워크스페이스 재실행에 실패했습니다. 다시 시도해 주세요.",
+    recreateFailed: "워크스페이스 재생성에 실패했습니다. 다시 시도해 주세요.",
+    deleteFailed: "워크스페이스 삭제에 실패했습니다. 다시 시도해 주세요.",
+    deleteConfirm: "워크스페이스를 삭제하시겠습니까?",
+    deleteIrreversible: "삭제 후에는 되돌릴 수 없습니다.",
+    tearingDown1: "기존 워크스페이스를 삭제하는 중입니다…",
+    tearingDown2: "삭제가 완료되면 워크스페이스 생성을 시작합니다.",
+    orphaned1: "콘솔이 재설치되어 이 워크스페이스와 연결할 수 없습니다.",
+    orphaned2: "기존에 저장된 데이터는 이전 보안 키로 암호화되어 복구할 수 없습니다.",
+    orphaned3: "삭제 후 재생성하면 빈 워크스페이스로 다시 시작합니다.",
+    reconnectExpired: "워크스페이스 연결이 만료되었습니다.",
+    reconnectPrompt: "재연결하여 데이터 플레인을 다시 활성화해 주세요.",
+    reconnectFailed: "재연결에 실패했습니다. 다시 시도해 주세요.",
+    loadFailed: "워크스페이스 정보를 불러올 수 없습니다.",
+    plan: "플랜",
+    statusLabel: "상태",
+    storedMemories: "저장된 기억 개수",
+    // Empty-workspace page (SC-02 states A/B/C)
+    pageAria: "워크스페이스 관리",
+    creatingTitle: "워크스페이스를 생성하는 중입니다…",
+    creatingDesc: "생성까지 약 3~5분 정도 소요됩니다.",
+    createFailedTitle: "워크스페이스 생성 실패",
+    createFailedDesc: "워크스페이스를 생성할 수 없습니다. 다시 시도해 주세요.",
+    createWorkspace: "워크스페이스 생성",
+    emptyTitle: "생성된 워크스페이스가 없습니다.",
+    emptyDesc: "워크스페이스를 생성하면 기억(memory)을 저장할 수 있습니다.",
+    // Console update floating card
+    updatingTitle: "콘솔을 업데이트하는 중입니다",
+    updateFailedTitle: "업데이트에 실패했습니다",
+    newVersionTitle: "새 버전이 출시되었습니다",
+    updateRunning: "백업 및 업데이트를 진행하고 있습니다…",
+    updatePreparing: "업데이트를 준비하고 있습니다…",
+    updateFailedBody:
+      "업데이트를 완료하지 못했습니다. 상태를 확인한 뒤 다시 시도해 주세요.",
+    updateRestartNotice:
+      "콘솔이 재시작되는 동안 RUNE 사용이 일시적으로 중단될 수 있습니다.",
+  },
+  validation: {
+    usernameRule: "한글, 영문 소문자, 단어 사이 공백 1칸만 입력할 수 있습니다.",
+  },
+};
diff --git a/frontend/src/pages/LoginPage.tsx b/frontend/src/pages/LoginPage.tsx
index 540cb66..a176ecc 100644
--- a/frontend/src/pages/LoginPage.tsx
+++ b/frontend/src/pages/LoginPage.tsx
@@ -7,6 +7,7 @@ import PublicNavbar from "@/components/navigation/PublicNavbar";
 import { useSessionQuery } from "@/hooks/queries/useSessionQuery";
 import { postAuthStart } from "@/api/authAPIs";
 import { redirectTo } from "@/utils/redirect";
+import { L } from "@/locales";
 import {
   BRAND_WORDMARK,
   BTN_TEXT,
@@ -56,9 +57,9 @@ const LoginPage = () => {
           {failed && (
             <p role="alert" className="text-negative text-md mb-4">
               <span className="text-muted-foreground">
-                로그인 중 문제가 발생했습니다.
+                {L.login.failed1}
                 <br />
-                다시 시도해 주세요.
+                {L.login.failed2}
               </span>
             </p>
           )}
@@ -72,7 +73,7 @@ const LoginPage = () => {
             />
             {!failed && (
               <p className="text-muted-foreground mt-3 text-sm">
-                콘솔을 사용하기 위해 RUNE 계정이 필요합니다.
+                {L.login.accountRequired}
               </p>
             )}
           </div>
diff --git a/frontend/src/pages/SessionsPage.tsx b/frontend/src/pages/SessionsPage.tsx
index 84097a9..b4e0b3a 100644
--- a/frontend/src/pages/SessionsPage.tsx
+++ b/frontend/src/pages/SessionsPage.tsx
@@ -14,6 +14,7 @@ import { useInvitationHistoryQuery } from "@/hooks/queries/useInvitationHistoryQ
 import { cn } from "@/utils/cn";
 import { formatDateTime } from "@/utils/formatDate";
 import { BTN_TEXT } from "@/constants/commonConstants";
+import { L } from "@/locales";
 import type { TDropdownOption } from "@/types/commonTypes";
 
 const styles = {
@@ -26,9 +27,9 @@ const styles = {
    sort query params (console API design §6). No status filter or
    issuance button: issuance lives in user/team management. */
 const SORT_OPTIONS: TDropdownOption[] = [
-  { value: "username", label: "멤버 이름" },
-  { value: "issued_at", label: "최근 발급 시간" },
-  { value: "last_access", label: "최근 접속 시간" },
+  { value: "username", label: L.common.memberName },
+  { value: "issued_at", label: L.members.lastIssued },
+  { value: "last_access", label: L.members.lastAccessedAt },
 ];
 
 /* 10 rows per page, fixed (SC-16 no.4) — the ?size=10 query param. */
@@ -74,15 +75,15 @@ const SessionsPage = () => {
   /* ── SC-16 state B — 조회 실패 ──────────────────────────────────── */
   if (historyQuery.isError) {
     return (
-      <section className={styles.page} aria-label="세션 기록">
+      <section className={styles.page} aria-label={L.nav.sessions}>
         <Feedback
           state="error"
           /* Taller, fully centered variant — the SC-16 state B canvas
              centers icon/text/button in a 180px-min panel, unlike the
              default left-aligned 92px row. */
           className="flex min-h-45 flex-col items-center justify-center text-center"
-          title="이력 정보를 불러올 수 없습니다."
-          description="새로고침 후 다시 시도해 주세요."
+          title={L.members.historyLoadError}
+          description={L.common.refreshRetry}
           action={
             <Button
               btnText={BTN_TEXT.refresh}
@@ -99,7 +100,7 @@ const SessionsPage = () => {
 
   /* ── SC-16 state A — 기본 ───────────────────────────────────────── */
   return (
-    <section className={styles.page} aria-label="세션 기록">
+    <section className={styles.page} aria-label={L.nav.sessions}>
       <Table
         fluid
         /* Fixed page height: thead 34px + 10 rows × 36px (h-9). Short
@@ -108,20 +109,20 @@ const SessionsPage = () => {
         scrollClassName="min-h-[394px]"
         toolbar={
           <div className="flex items-center gap-2 px-4 py-4">
-            <span className="text-md text-faint">정렬 기준</span>
+            <span className="text-md text-faint">{L.common.sortBy}</span>
             <Dropdown
               options={SORT_OPTIONS}
               value={sort}
               onChange={changeSort}
               size="sm"
-              ariaLabel="정렬"
+              ariaLabel={L.common.sort}
               className="w-40"
             />
           </div>
         }
         foot={
           <TableFoot
-            info={`총 ${total}건 · ${PAGE_SIZE}건/페이지`}
+            info={L.members.sessionPageInfo(total, PAGE_SIZE)}
             className="flex-row"
           >
             <Pagination
@@ -135,9 +136,13 @@ const SessionsPage = () => {
         {/* Fixed column widths — auto layout would resize per page's
             content and shift the headers while paginating. */}
         <TableHead>
-          <TableHeaderCell className="w-2/5">사용자</TableHeaderCell>
-          <TableHeaderCell className="w-[30%]">발급 시간</TableHeaderCell>
-          <TableHeaderCell className="w-[30%]">최근 접속 시간</TableHeaderCell>
+          <TableHeaderCell className="w-2/5">{L.common.users}</TableHeaderCell>
+          <TableHeaderCell className="w-[30%]">
+            {L.members.issuedAt}
+          </TableHeaderCell>
+          <TableHeaderCell className="w-[30%]">
+            {L.members.lastAccessedAt}
+          </TableHeaderCell>
         </TableHead>
         <tbody>
           {historyQuery.isPending && (
@@ -146,7 +151,7 @@ const SessionsPage = () => {
                 colSpan={3}
                 className="text-faint px-3 py-8 text-center text-sm"
               >
-                불러오는 중…
+                {L.common.loading}
               </td>
             </tr>
           )}
@@ -156,7 +161,7 @@ const SessionsPage = () => {
                 colSpan={3}
                 className="text-muted-foreground border-t px-3 py-8 text-center text-sm"
               >
-                이력이 없습니다.
+                {L.members.noHistory}
               </td>
             </tr>
           )}
diff --git a/frontend/src/pages/TeamsPage.tsx b/frontend/src/pages/TeamsPage.tsx
index 7ed5b80..d8a13c9 100644
--- a/frontend/src/pages/TeamsPage.tsx
+++ b/frontend/src/pages/TeamsPage.tsx
@@ -12,12 +12,13 @@ import { useTeamsTreeQuery } from "@/hooks/queries/useTeamsTreeQuery";
 import { parseErrorCode } from "@/api/parseError";
 import { cn } from "@/utils/cn";
 import { BTN_TEXT } from "@/constants/commonConstants";
+import { L } from "@/locales";
 import { useNoticeStore } from "@/stores/noticeStore";
 
 /** Create-team error codes → SC-07 copy (shared with TreeDetailView). */
 const CREATE_TEAM_REASON: Record<string, string> = {
-  TEAM_NAME_DUPLICATE: "같은 상위 팀에 동일한 이름이 이미 있습니다.",
-  TEAM_NAME_INVALID: "팀 이름 형식이 올바르지 않습니다.",
+  TEAM_NAME_DUPLICATE: L.teams.dupName,
+  TEAM_NAME_INVALID: L.teams.invalidTeamName,
 };
 
 const feedbackPanel =
@@ -70,11 +71,11 @@ const TeamsPage = () => {
       {
         onSuccess: () => {
           setCreateOpen(false);
-          showNotice("팀 생성", "팀이 생성되었습니다.", "success");
+          showNotice(L.teams.createTeamTitle, L.teams.teamCreated, "success");
         },
         onError: async (res) => {
           const code = await parseErrorCode(res);
-          setCreateError(CREATE_TEAM_REASON[code] ?? "팀 생성에 실패했습니다.");
+          setCreateError(CREATE_TEAM_REASON[code] ?? L.teams.createTeamFailed);
         },
       },
     );
@@ -120,18 +121,18 @@ const TeamsPage = () => {
 
   if (isPending) {
     return (
-      <section className={styles.panel} aria-label="팀 관리">
+      <section className={styles.panel} aria-label={L.nav.teams}>
         <div className={styles.header} />
       </section>
     );
   }
   if (isError) {
     return (
-      <section className={styles.panel} aria-label="팀 관리">
+      <section className={styles.panel} aria-label={L.nav.teams}>
         <Feedback
           state="error"
-          title="팀 정보를 불러올 수 없습니다."
-          description="새로고침 후 다시 시도해 주세요."
+          title={L.teams.teamsLoadError}
+          description={L.common.refreshRetry}
           className={feedbackPanel}
           action={
             <Button
@@ -148,9 +149,13 @@ const TeamsPage = () => {
   }
 
   return (
-    <section className={styles.panel} aria-label="팀 관리">
+    <section className={styles.panel} aria-label={L.nav.teams}>
       <div className={styles.header}>
-        <div className={styles.segment} role="group" aria-label="보기 전환">
+        <div
+          className={styles.segment}
+          role="group"
+          aria-label={L.teams.switchView}
+        >
           <button
             type="button"
             className={cn(
@@ -159,7 +164,7 @@ const TeamsPage = () => {
             aria-pressed={view === "tree"}
             onClick={() => setView("tree")}
           >
-            트리·상세
+            {L.teams.treeDetail}
           </button>
           <button
             type="button"
@@ -169,7 +174,7 @@ const TeamsPage = () => {
             aria-pressed={view === "org"}
             onClick={() => setView("org")}
           >
-            조직도
+            {L.teams.orgChartView}
           </button>
         </div>
         {/* Nothing to search when there are no teams (SC-06 state B). */}
@@ -177,7 +182,7 @@ const TeamsPage = () => {
           <SearchInput
             value={teamSearch}
             onChange={setTeamSearch}
-            placeholder="팀 검색"
+            placeholder={L.teams.searchTeams}
             maxLength={50}
             className="ml-auto w-55"
           />
@@ -187,8 +192,8 @@ const TeamsPage = () => {
       {teams.length === 0 ? (
         <Feedback
           state="empty"
-          title="새로운 팀을 만들어 주세요."
-          description="팀을 생성하면 멤버와 기억(memory)을 관리할 수 있습니다."
+          title={L.teams.emptyTitle}
+          description={L.teams.emptyDesc}
           className={feedbackPanel}
           action={
             <Button
diff --git a/frontend/src/pages/UsersPage.tsx b/frontend/src/pages/UsersPage.tsx
index 0801305..c2c43eb 100644
--- a/frontend/src/pages/UsersPage.tsx
+++ b/frontend/src/pages/UsersPage.tsx
@@ -37,6 +37,7 @@ import { useUsersQuery } from "@/hooks/queries/useUsersQuery";
 import { useDebouncedValue } from "@/hooks/useDebouncedValue";
 import { parseErrorCode } from "@/api/parseError";
 import { BTN_TEXT } from "@/constants/commonConstants";
+import { L } from "@/locales";
 import type { TDropdownOption } from "@/types/commonTypes";
 import type { TTeamMemberRole, TTeamTree } from "@/types/teamTypes";
 import type {
@@ -59,9 +60,9 @@ const styles = {
 /* Filter/sort option sets (SC-11 no.2–3). "all" stands in for 전체. The list
    shows only the session axis, so the filter matches it. */
 const STATUS_OPTIONS: TDropdownOption[] = [
-  { value: "all", label: "전체" },
-  { value: "online", label: "온라인" },
-  { value: "offline", label: "오프라인" },
+  { value: "all", label: L.common.all },
+  { value: "online", label: L.status.member.online },
+  { value: "offline", label: L.status.member.offline },
 ];
 
 /* Depth indent stripped — the 150px filter trigger can't fit deep-tree
@@ -70,13 +71,13 @@ const STATUS_OPTIONS: TDropdownOption[] = [
    Computed in-component (buildTeamOptions depends on the real teams
    query result — no static dummy list anymore). */
 const buildGroupOptions = (teams: TTeamTree): TDropdownOption[] => [
-  { value: "all", label: "전체" },
+  { value: "all", label: L.common.all },
   ...buildTeamOptions(teams).map(({ value, label }) => ({ value, label })),
 ];
 
 const SORT_OPTIONS: TDropdownOption[] = [
-  { value: "last_invited", label: "최근 초대 코드 발송" },
-  { value: "username", label: "멤버 이름" },
+  { value: "last_invited", label: L.members.lastInviteSent },
+  { value: "username", label: L.common.memberName },
 ];
 
 /** First membership as "team · role"; the rest collapse into "+n". */
@@ -93,7 +94,7 @@ const PAGE_SIZE = 10;
 
 /** Batch-delete failure reasons shown by account (DELETE /users). */
 const BATCH_REASON: Record<string, string> = {
-  USER_NOT_FOUND: "사용자를 찾을 수 없습니다",
+  USER_NOT_FOUND: L.teams.userNotFound,
 };
 
 /**
@@ -235,11 +236,18 @@ const UsersPage = () => {
     );
     const failed = targets.filter((_, i) => results[i].status === "rejected");
     if (failed.length === 0) {
-      showNotice("초대 코드 재전송", "초대 코드를 재전송했습니다.", "info");
+      showNotice(
+        BTN_TEXT.resendInvitationCode,
+        L.members.inviteCodeResent,
+        "info",
+      );
       return;
     }
     setBatchFailures(
-      failed.map((u) => ({ account: u.account, reason: "재전송 실패" })),
+      failed.map((u) => ({
+        account: u.account,
+        reason: L.members.resendFailedShort,
+      })),
     );
   };
 
@@ -266,7 +274,7 @@ const UsersPage = () => {
     }
 
     if (result.failed.length === 0) {
-      showNotice("멤버 삭제", "멤버를 삭제했습니다.", "info");
+      showNotice(L.members.deleteMembersTitle, L.members.membersDeleted, "info");
       return;
     }
     if (succeededIds.length === 0) {
@@ -283,11 +291,11 @@ const UsersPage = () => {
   /* ── SC-11 state C — 조회 실패 ──────────────────────────────────── */
   if (usersQuery.isError) {
     return (
-      <section className={styles.page} aria-label="멤버 관리">
+      <section className={styles.page} aria-label={L.nav.users}>
         <Feedback
           state="error"
-          title="멤버 정보를 불러올 수 없습니다."
-          description="새로고침 후 다시 시도해 주세요."
+          title={L.members.membersLoadError}
+          description={L.common.refreshRetry}
           action={
             <Button
               btnText={BTN_TEXT.refresh}
@@ -306,11 +314,11 @@ const UsersPage = () => {
      all hidden) ─── */
   if (!usersQuery.isPending && total === 0 && !hasActiveFilter) {
     return (
-      <section className={styles.page} aria-label="멤버 관리">
+      <section className={styles.page} aria-label={L.nav.users}>
         <Feedback
           state="empty"
-          title="아직 초대한 멤버가 없습니다"
-          description="멤버를 초대하면 초대 코드가 이메일로 발송됩니다"
+          title={L.members.noMembersYet}
+          description={L.members.inviteHint}
           action={
             <Button
               btnText={BTN_TEXT.inviteMember}
@@ -333,7 +341,7 @@ const UsersPage = () => {
   }
 
   return (
-    <section className={styles.page} aria-label="멤버 관리">
+    <section className={styles.page} aria-label={L.nav.users}>
       <Table
         fluid
         /* Fixed page height: thead 36px + 10 rows × 49px (h-8 status chip
@@ -347,42 +355,44 @@ const UsersPage = () => {
                 <SearchInput
                   value={search}
                   onChange={withPageReset(setSearch)}
-                  placeholder="이름 검색"
+                  placeholder={L.members.searchByName}
                   maxLength={100}
                   className="w-50"
                 />
                 {/* filter/order dropdown */}
                 <div className="flex items-center gap-4">
                   <div className="flex items-center gap-2">
-                    <span className="text-md text-faint">정렬 기준</span>
+                    <span className="text-md text-faint">{L.common.sortBy}</span>
                     <Dropdown
                       options={SORT_OPTIONS}
                       value={sort}
                       onChange={withPageReset(setSort)}
                       size="sm"
-                      ariaLabel="정렬"
+                      ariaLabel={L.common.sort}
                       className="w-36"
                     />
                   </div>
                   <div className="flex items-center gap-2">
-                    <span className="text-md text-faint">멤버 상태</span>
+                    <span className="text-md text-faint">
+                      {L.common.memberStatus}
+                    </span>
                     <Dropdown
                       options={STATUS_OPTIONS}
                       value={statusFilter}
                       onChange={withPageReset(setStatusFilter)}
                       size="sm"
-                      ariaLabel="status 필터"
+                      ariaLabel={L.members.statusFilterAria}
                       className="w-32"
                     />
                   </div>
                   <div className="flex items-center gap-2">
-                    <span className="text-md text-faint">팀</span>
+                    <span className="text-md text-faint">{L.common.team}</span>
                     <Dropdown
                       options={groupOptions}
                       value={groupFilter}
                       onChange={withPageReset(setGroupFilter)}
                       size="sm"
-                      ariaLabel="group 필터"
+                      ariaLabel={L.members.teamFilterAria}
                       className="w-40"
                     />
                   </div>
@@ -420,7 +430,7 @@ const UsersPage = () => {
         }
         foot={
           <TableFoot
-            info={`총 ${total}명 · ${PAGE_SIZE}명/페이지`}
+            info={L.teams.memberPageInfo(total, PAGE_SIZE)}
             className="flex-row"
           >
             <Pagination
@@ -436,14 +446,20 @@ const UsersPage = () => {
             <Checkbox
               checked={allSelected}
               onChange={toggleAll}
-              ariaLabel="전체 선택"
+              ariaLabel={L.common.selectAll}
             />
           </TableHeaderCell>
           {/* Fixed column widths — auto layout would resize per page's
               content and shift the headers while paginating. */}
-          <TableHeaderCell className="w-[40%]">멤버 이름</TableHeaderCell>
-          <TableHeaderCell className="w-[20%]">멤버 상태</TableHeaderCell>
-          <TableHeaderCell className="w-[40%]">팀 (권한)</TableHeaderCell>
+          <TableHeaderCell className="w-[40%]">
+            {L.common.memberName}
+          </TableHeaderCell>
+          <TableHeaderCell className="w-[20%]">
+            {L.common.memberStatus}
+          </TableHeaderCell>
+          <TableHeaderCell className="w-[40%]">
+            {L.members.teamRoleHeader}
+          </TableHeaderCell>
         </TableHead>
         <tbody>
           {usersQuery.isPending && (
@@ -452,7 +468,7 @@ const UsersPage = () => {
                 colSpan={4}
                 className="text-faint px-3 py-8 text-center text-sm"
               >
-                불러오는 중…
+                {L.common.loading}
               </td>
             </tr>
           )}
@@ -462,7 +478,7 @@ const UsersPage = () => {
                 colSpan={4}
                 className="text-muted-foreground border-t px-3 py-8 text-center text-sm"
               >
-                검색 결과가 없습니다.
+                {L.common.noResults}
               </td>
             </tr>
           )}
@@ -480,7 +496,7 @@ const UsersPage = () => {
                     <Checkbox
                       checked={selectedIds.has(user.userId)}
                       onChange={(checked) => toggleOne(user.userId, checked)}
-                      ariaLabel={`${user.account} 선택`}
+                      ariaLabel={L.common.selectName(user.account)}
                     />
                   </div>
                 </TableCell>
diff --git a/frontend/src/pages/WorkspacePage.tsx b/frontend/src/pages/WorkspacePage.tsx
index 7108f89..680a857 100644
--- a/frontend/src/pages/WorkspacePage.tsx
+++ b/frontend/src/pages/WorkspacePage.tsx
@@ -9,6 +9,7 @@ import {
   useWorkspaceQuery,
 } from "@/hooks/queries/useWorkspaceQuery";
 import { PATH_LIST } from "@/constants/commonConstants";
+import { L } from "@/locales";
 import { useWorkspaceStore } from "@/stores/workspaceStore";
 
 const panelClass =
@@ -62,7 +63,7 @@ const WorkspacePage = () => {
   const exists = workspace != null;
   const transitional = exists && isTransitionalStatus(workspace.status);
 
-  if (isLoading) return <section aria-label="워크스페이스 관리" />;
+  if (isLoading) return <section aria-label={L.workspace.pageAria} />;
 
   /* A workspace exists → go to the console. The one exception is our own
      create still provisioning: stay and keep the spinner until it runs. */
@@ -84,29 +85,29 @@ const WorkspacePage = () => {
     transitional;
 
   return (
-    <section aria-label="워크스페이스 관리">
+    <section aria-label={L.workspace.pageAria}>
       {creating ? (
         <Feedback
           state="loading"
-          title="워크스페이스를 생성하는 중입니다…"
-          description="생성까지 약 3~5분 정도 소요됩니다."
+          title={L.workspace.creatingTitle}
+          description={L.workspace.creatingDesc}
           className={panelClass}
         />
       ) : createMutation.isError ? (
         <Feedback
           state="error"
-          title="워크스페이스 생성 실패"
-          description="워크스페이스를 생성할 수 없습니다. 다시 시도해 주세요."
+          title={L.workspace.createFailedTitle}
+          description={L.workspace.createFailedDesc}
           className={panelClass}
-          action={createButton("워크스페이스 생성", handleCreate)}
+          action={createButton(L.workspace.createWorkspace, handleCreate)}
         />
       ) : (
         <Feedback
           state="empty"
-          title="생성된 워크스페이스가 없습니다."
-          description="워크스페이스를 생성하면 기억(memory)을 저장할 수 있습니다."
+          title={L.workspace.emptyTitle}
+          description={L.workspace.emptyDesc}
           className={panelClass}
-          action={createButton("워크스페이스 생성", handleCreate)}
+          action={createButton(L.workspace.createWorkspace, handleCreate)}
         />
       )}
     </section>
diff --git a/frontend/src/test/setup.ts b/frontend/src/test/setup.ts
index 7f3db81..e42284a 100644
--- a/frontend/src/test/setup.ts
+++ b/frontend/src/test/setup.ts
@@ -1,5 +1,11 @@
 import "@testing-library/jest-dom/vitest";
 
+// Pin the test language to Korean BEFORE any module imports @/locales (setup
+// runs ahead of test-file module graphs; the locale is chosen once at import):
+// the suite's assertions are written against the Korean copy, and jsdom's
+// navigator.language would otherwise pick en.
+window.localStorage.setItem("rc_lang", "ko");
+
 import { cleanup } from "@testing-library/react";
 import { afterEach } from "vitest";
 
diff --git a/frontend/src/utils/username.ts b/frontend/src/utils/username.ts
index ee1e945..337f197 100644
--- a/frontend/src/utils/username.ts
+++ b/frontend/src/utils/username.ts
@@ -1,10 +1,11 @@
 /** Username (표시용 사용자 이름) rules — API design §공통 계약 (2026-07-20):
  * 한글·영문 소문자만, 단어 사이 공백 1칸(양끝 공백 금지), 1~50자. */
 
+import { L } from "@/locales";
+
 export const USERNAME_MAX_LENGTH = 50;
 
-export const USERNAME_FORMAT_ERROR =
-  "한글, 영문 소문자, 단어 사이 공백 1칸만 입력할 수 있습니다.";
+export const USERNAME_FORMAT_ERROR = L.validation.usernameRule;
 
 /* Compatibility jamo (ㄱ-ㅎ·ㅏ-ㅣ) are accepted while typing so an
    in-progress IME composition never flags as invalid mid-keystroke;

From dbd9141a8cd79472f2af14dccb161dd3ba9c81c8 Mon Sep 17 00:00:00 2001
From: Matthew Laszcz <mlaszcz@cryptolab.co.kr>
Date: Tue, 4 Aug 2026 09:38:49 +0900
Subject: [PATCH 2/4] copy: standardize brand to all-caps RUNE in console
 locale copy
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Normalize brand 'Rune'/'rune' → 'RUNE' in the en/ko locale tables
(account-required, invite status, update notice). Technical identifiers
are unaffected (none present in the locale files).
---
 frontend/src/locales/en.ts | 8 ++++----
 frontend/src/locales/ko.ts | 4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/frontend/src/locales/en.ts b/frontend/src/locales/en.ts
index 7fb6e6b..4232658 100644
--- a/frontend/src/locales/en.ts
+++ b/frontend/src/locales/en.ts
@@ -93,7 +93,7 @@ export const en = {
     invitation: {
       pending: "Invitation Pending",
       expired: "Invitation Code Expired",
-      redeemed: "Invitation Code Used",
+      redeemed: "Invitation code sent",
     },
     workspace: {
       provisioning: "Creating",
@@ -156,7 +156,7 @@ export const en = {
     selectRole: "Select Role",
     // Sentence split around the inline member-status chip: prefix + status + suffix.
     invitePrefix:
-      "Once the invited user connects rune, their status changes to ",
+      "Once the invited user connects RUNE, their status changes to ",
     inviteSuffix: ".",
     // Team name / create / rename
     teamNameRule: "Only numbers, Korean and English letters, - and _ are allowed.",
@@ -259,7 +259,7 @@ export const en = {
     reason: "Reason",
     // Sentence split around the inline member-status chip: prefix + status + suffix.
     invitePrefix:
-      "When invited, the user receives an invitation code; once they connect rune within 24 hours, their status changes to ",
+      "When invited, the user receives an invitation code; once they connect RUNE within 24 hours, their status changes to ",
     inviteSuffix: ".",
     inviteExpiry:
       "If they do not connect, the code expires and you can invite them again with Resend Invitation Code.",
@@ -310,7 +310,7 @@ export const en = {
     noInvitationToCancel: "No invitation to cancel.",
     cancelInvitationFailed: "Failed to cancel invitation. Please try again.",
     // Users page (SC-11)
-    lastInviteSent: "Last Invitation Code Sent",
+    lastInviteSent: "Invitation Code",
     resendFailedShort: "Resend failed",
     deleteMembersTitle: "Delete Members",
     membersDeleted: "Members deleted.",
diff --git a/frontend/src/locales/ko.ts b/frontend/src/locales/ko.ts
index 430c72b..0cd6509 100644
--- a/frontend/src/locales/ko.ts
+++ b/frontend/src/locales/ko.ts
@@ -154,7 +154,7 @@ export const ko: TLocale = {
     roleLabel: "권한 (role)",
     selectRole: "권한 선택",
     // 인라인 멤버 상태 칩을 사이에 둔 문장 분할: prefix + status + suffix.
-    invitePrefix: "초대받은 사용자가 rune을 연결하면 ",
+    invitePrefix: "초대받은 사용자가 RUNE을 연결하면 ",
     inviteSuffix: "으로 전환됩니다.",
     // Team name / create / rename
     teamNameRule: "숫자·한글·영어와 - _ 만 사용할 수 있습니다.",
@@ -253,7 +253,7 @@ export const ko: TLocale = {
     reason: "사유",
     // 인라인 멤버 상태 칩을 사이에 둔 문장 분할: prefix + status + suffix.
     invitePrefix:
-      "초대 시 사용자에게 초대 코드가 발송되어 사용자가 24시간 내 rune을 연결하면 ",
+      "초대 시 사용자에게 초대 코드가 발송되어 사용자가 24시간 내 RUNE을 연결하면 ",
     inviteSuffix: " 으로 전환됩니다.",
     inviteExpiry:
       "미연결 시 코드가 만료되고 초대 코드 재전송으로 사용자를 다시 초대할 수 있습니다.",

From 3e5771c3c15870e8f2016d1da6d8b8c8349c17c2 Mon Sep 17 00:00:00 2001
From: Matthew Laszcz <mlaszcz@cryptolab.co.kr>
Date: Tue, 4 Aug 2026 09:38:49 +0900
Subject: [PATCH 3/4] feat(i18n): live language switching via i18next, no
 reload flash
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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Drive language state with plain i18next; L becomes a Proxy over the active
locale table so all L.x.y call sites and the compile-time-typed tables are
unchanged. A LocaleProvider subscribes to i18next's languageChanged and
remounts its subtree, so switching re-renders in place instead of
window.location.reload() — removing the switch flash. setLanguage calls
changeLanguage (keeps localStorage persistence); LanguageToggle reads the
live language via getLanguage(). Locale test compares L by structure since
it is now a Proxy.
---
 frontend/package.json                         |  1 +
 frontend/src/components/LocaleProvider.tsx    | 27 ++++++++
 .../components/navigation/LanguageToggle.tsx  | 11 +--
 .../src/locales/__tests__/locales.test.ts     |  4 +-
 frontend/src/locales/index.ts                 | 67 ++++++++++++++++---
 frontend/src/main.tsx                         | 13 ++--
 6 files changed, 102 insertions(+), 21 deletions(-)
 create mode 100644 frontend/src/components/LocaleProvider.tsx

diff --git a/frontend/package.json b/frontend/package.json
index 93d13d2..226032b 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -19,6 +19,7 @@
   "dependencies": {
     "@tanstack/react-query": "^5.101.2",
     "clsx": "^2.1.1",
+    "i18next": "^26.3.6",
     "lucide-react": "^1.24.0",
     "pretendard": "^1.3.9",
     "react": "^19.2.7",
diff --git a/frontend/src/components/LocaleProvider.tsx b/frontend/src/components/LocaleProvider.tsx
new file mode 100644
index 0000000..627458a
--- /dev/null
+++ b/frontend/src/components/LocaleProvider.tsx
@@ -0,0 +1,27 @@
+import { useEffect, useState, type ReactNode } from "react";
+
+import { i18n } from "@/locales";
+
+/**
+ * LocaleProvider makes the module-global `L` Proxy reactive without a page
+ * reload. `L.x.y` reads the current language on every access, but a module
+ * global can't tell React to re-render — so this boundary subscribes to
+ * i18next's `languageChanged` event and remounts its subtree (via a changing
+ * `key`) when the language switches. The tree then re-renders in place — no
+ * reload, so no flash — and every `L.x.y` re-resolves to the new language.
+ */
+export default function LocaleProvider({ children }: { children: ReactNode }) {
+  const [lang, setLang] = useState(i18n.language);
+
+  useEffect(() => {
+    const onChange = (next: string) => setLang(next);
+    i18n.on("languageChanged", onChange);
+    if (i18n.language !== lang) setLang(i18n.language);
+    return () => {
+      i18n.off("languageChanged", onChange);
+    };
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+
+  return <div key={lang}>{children}</div>;
+}
diff --git a/frontend/src/components/navigation/LanguageToggle.tsx b/frontend/src/components/navigation/LanguageToggle.tsx
index 4dbb9ce..3a48cf4 100644
--- a/frontend/src/components/navigation/LanguageToggle.tsx
+++ b/frontend/src/components/navigation/LanguageToggle.tsx
@@ -1,17 +1,18 @@
 import { Globe } from "lucide-react";
 
-import { language, setLanguage } from "@/locales";
+import { getLanguage, setLanguage } from "@/locales";
 
 /**
  * LanguageToggle is the always-visible navbar language switch (globe + label,
  * the top-right convention users scan for). The label names the language it
  * switches TO, in that language's own script, so a user stuck in the wrong
- * language can still recognize the way out. setLanguage persists the choice
- * and reloads — the locale is bound once at page load (see src/locales).
+ * language can still recognize the way out. setLanguage switches i18next in
+ * place (no reload — LocaleProvider re-renders). Reads getLanguage() at render
+ * (not the load-time const) so after a switch it offers the other direction.
  */
 const LanguageToggle = () => {
-  const nextLanguage = language === "ko" ? "en" : "ko";
-  const nextLanguageLabel = language === "ko" ? "English" : "한국어";
+  const nextLanguage = getLanguage() === "ko" ? "en" : "ko";
+  const nextLanguageLabel = getLanguage() === "ko" ? "English" : "한국어";
 
   return (
     <button
diff --git a/frontend/src/locales/__tests__/locales.test.ts b/frontend/src/locales/__tests__/locales.test.ts
index 7157771..0e33d1c 100644
--- a/frontend/src/locales/__tests__/locales.test.ts
+++ b/frontend/src/locales/__tests__/locales.test.ts
@@ -17,7 +17,9 @@ import { WORKSPACE_STATUS_VAR } from "@/constants/styleConstants";
 describe("locales", () => {
   it("resolves Korean under the test pin (setup.ts sets rc_lang=ko)", () => {
     expect(language).toBe("ko");
-    expect(L).toBe(ko);
+    // L is now a Proxy over the active table (not the raw object), so compare
+    // by structure rather than reference.
+    expect(L).toStrictEqual(ko);
     expect(BTN_TEXT.close).toBe("닫기");
     expect(MODAL_TITLES.deleteTeam("platform")).toBe("팀 삭제 — platform");
     expect(MODAL_TITLES.deleteMemberBulk(3)).toBe("멤버 삭제 (3명)");
diff --git a/frontend/src/locales/index.ts b/frontend/src/locales/index.ts
index a3c95a5..8f96920 100644
--- a/frontend/src/locales/index.ts
+++ b/frontend/src/locales/index.ts
@@ -1,3 +1,12 @@
+// Bilingual locale system — i18next drives the language LIFECYCLE (init,
+// changeLanguage, the languageChanged event LocaleProvider re-renders on),
+// while the two static, compile-time-typed tables (en.ts / ko.ts) remain the
+// string source. `L` is a Proxy over the active table, so all `L.x.y` call
+// sites and the type safety (ko.ts satisfies `typeof en`) stay unchanged, and
+// switching now re-renders in place instead of reloading — no switch flash.
+
+import i18n from "i18next";
+
 import { en, type TLocale } from "./en";
 import { ko } from "./ko";
 
@@ -7,6 +16,8 @@ export const LANG_STORAGE_KEY = "rc_lang";
 
 export type TLanguage = "en" | "ko";
 
+const locales: Record<TLanguage, TLocale> = { en, ko };
+
 const detectLanguage = (): TLanguage => {
   try {
     const stored = localStorage.getItem(LANG_STORAGE_KEY);
@@ -17,21 +28,57 @@ const detectLanguage = (): TLanguage => {
   return navigator.language?.toLowerCase().startsWith("ko") ? "ko" : "en";
 };
 
-/** language is resolved ONCE at page load and never changes within a visit —
- * every string read below is a plain static property access. */
-export const language: TLanguage = detectLanguage();
+// Initialize i18next once. Resources are minimal — copy comes from the typed
+// tables via `L`, not i18next's t(); i18next is the language state machine +
+// change-event source that LocaleProvider subscribes to.
+if (!i18n.isInitialized) {
+  void i18n.init({
+    lng: detectLanguage(),
+    fallbackLng: "en",
+    resources: { en: { translation: {} }, ko: { translation: {} } },
+    interpolation: { escapeValue: false },
+  });
+}
+
+export { i18n };
+
+/** getLanguage returns the currently active language. Reactive callers read
+ * this inside render so a re-render (see LocaleProvider) picks up a change. */
+export const getLanguage = (): TLanguage =>
+  (i18n.language as TLanguage) === "ko" ? "ko" : "en";
+
+/** language is the language at module-eval time — kept for load-time-only
+ * consumers. Prefer getLanguage() in anything that must react to a switch. */
+export const language: TLanguage = getLanguage();
 
-/** L is the active locale table. Import L and read L.btn.close etc.; the
- * value is the same hardcoded string on every access for the whole visit. */
-export const L: TLocale = language === "ko" ? ko : en;
+/** L is the active locale table, resolved per access against the current
+ * language, so a re-render after a switch shows the new copy. */
+export const L: TLocale = new Proxy({} as TLocale, {
+  get(_t, prop: string | symbol) {
+    return locales[getLanguage()][prop as keyof TLocale];
+  },
+  has(_t, prop) {
+    return prop in locales[getLanguage()];
+  },
+  ownKeys() {
+    return Reflect.ownKeys(locales[getLanguage()]);
+  },
+  getOwnPropertyDescriptor(_t, prop) {
+    return Reflect.getOwnPropertyDescriptor(
+      locales[getLanguage()],
+      prop as keyof TLocale,
+    );
+  },
+});
 
-/** setLanguage persists the choice and reloads — the locale is bound at page
- * load (see above), so a reload is what applies the new language everywhere. */
+/** setLanguage persists the choice and switches i18next in place — no reload,
+ * so the UI swaps languages without the reload flash (LocaleProvider re-renders
+ * the tree on i18next's languageChanged event). */
 export const setLanguage = (lang: TLanguage) => {
   try {
     localStorage.setItem(LANG_STORAGE_KEY, lang);
   } catch {
-    /* storage unavailable — reload alone keeps the browser-language default */
+    /* storage unavailable — the in-memory switch below still applies it */
   }
-  window.location.reload();
+  void i18n.changeLanguage(lang);
 };
diff --git a/frontend/src/main.tsx b/frontend/src/main.tsx
index 444bff3..a716f77 100644
--- a/frontend/src/main.tsx
+++ b/frontend/src/main.tsx
@@ -3,16 +3,19 @@ import { BrowserRouter } from "react-router";
 import { createRoot } from "react-dom/client";
 
 import QueryProvider from "@/state/tanstackQuery/QueryProvider";
+import LocaleProvider from "@/components/LocaleProvider";
 import App from "@/App";
 
 import "./index.css";
 
 createRoot(document.getElementById("root")!).render(
   <StrictMode>
-    <QueryProvider>
-      <BrowserRouter>
-        <App />
-      </BrowserRouter>
-    </QueryProvider>
+    <LocaleProvider>
+      <QueryProvider>
+        <BrowserRouter>
+          <App />
+        </BrowserRouter>
+      </QueryProvider>
+    </LocaleProvider>
   </StrictMode>,
 );

From 7213a660ff62e5e90315383b351d83c6d1df2935 Mon Sep 17 00:00:00 2001
From: Matthew Laszcz <mlaszcz@cryptolab.co.kr>
Date: Tue, 4 Aug 2026 10:08:15 +0900
Subject: [PATCH 4/4] chore(frontend): sync pnpm-lock.yaml with i18next
 dependency

CI installs with --frozen-lockfile; add the i18next entry so the lockfile
matches package.json.
---
 frontend/pnpm-lock.yaml | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/frontend/pnpm-lock.yaml b/frontend/pnpm-lock.yaml
index f1fc272..76b8f4b 100644
--- a/frontend/pnpm-lock.yaml
+++ b/frontend/pnpm-lock.yaml
@@ -14,6 +14,9 @@ importers:
       clsx:
         specifier: ^2.1.1
         version: 2.1.1
+      i18next:
+        specifier: ^26.3.6
+        version: 26.3.6(typescript@6.0.3)
       lucide-react:
         specifier: ^1.24.0
         version: 1.24.0(react@19.2.7)
@@ -1029,6 +1032,14 @@ packages:
     resolution: {integrity: sha512-CV9TW3Y3f8/wT0BRFc1/KAVQ3TUHiXmaAb6VW9vtiMFf7SLoMd1PdAc4W3KFOFETBJUb90KatHqlsZMWV+R9Gg==}
     engines: {node: ^20.19.0 || ^22.12.0 || >=24.0.0}
 
+  i18next@26.3.6:
+    resolution: {integrity: sha512-Bu5Z2nAXgfVyM8xvW3jk9EKRIuX37PudsrBViThNFx7CR7aaYTpP01cxNB/E4c4UUzTDiAZRstEhsRfPOL/8xA==}
+    peerDependencies:
+      typescript: ^5 || ^6 || ^7
+    peerDependenciesMeta:
+      typescript:
+        optional: true
+
   ignore@5.3.2:
     resolution: {integrity: sha512-hsBTNUqQTDwkWtcdYI2i06Y/nUBEsNEDJKjWdigLvegy8kDuJAS8uRlpkkcQpyEXL0Z/pjDy5HBmMjRCJ2gq+g==}
     engines: {node: '>= 4'}
@@ -2573,6 +2584,10 @@ snapshots:
     transitivePeerDependencies:
       - '@noble/hashes'
 
+  i18next@26.3.6(typescript@6.0.3):
+    optionalDependencies:
+      typescript: 6.0.3
+
   ignore@5.3.2: {}
 
   ignore@7.0.5: {}