diff --git a/common/.gitkeep b/common/.gitkeep
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/common/.gitkeep
@@ -0,0 +1 @@
+
diff --git a/common/core/auth/.gitkeep b/common/core/auth/.gitkeep
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/common/core/auth/.gitkeep
@@ -0,0 +1 @@
+
diff --git a/common/core/i18n/index.ts b/common/core/i18n/index.ts
new file mode 100644
index 00000000..77517663
--- /dev/null
+++ b/common/core/i18n/index.ts
@@ -0,0 +1,11 @@
+export { createTomlTranslator } from "./loader";
+export {
+  DEFAULT_LOCALE,
+  LOCALE_STORAGE_KEY,
+  SUPPORTED_LOCALES,
+  type Locale,
+  type TomlObject,
+  type TomlValue,
+  type TranslatorInput,
+  type TranslatorOptions,
+} from "./types";
diff --git a/common/core/i18n/loader.ts b/common/core/i18n/loader.ts
new file mode 100644
index 00000000..71d1decd
--- /dev/null
+++ b/common/core/i18n/loader.ts
@@ -0,0 +1,176 @@
+import {
+  DEFAULT_LOCALE,
+  LOCALE_STORAGE_KEY,
+  SUPPORTED_LOCALES,
+  type Locale,
+  type TomlObject,
+  type TomlValue,
+  type TranslatorInput,
+  type TranslatorOptions,
+} from "./types";
+
+function mergeTomlObjects(base: TomlObject, override: TomlObject): TomlObject {
+  const result: TomlObject = { ...base };
+
+  for (const [key, value] of Object.entries(override)) {
+    const currentValue = result[key];
+    if (
+      typeof currentValue === "object" &&
+      currentValue !== null &&
+      typeof value === "object" &&
+      value !== null
+    ) {
+      result[key] = mergeTomlObjects(currentValue as TomlObject, value);
+      continue;
+    }
+    result[key] = value;
+  }
+
+  return result;
+}
+
+function isSupportedLocale(value: string): value is Locale {
+  return (SUPPORTED_LOCALES as readonly string[]).includes(value);
+}
+
+function parseToml(raw: string): TomlObject {
+  const lines = raw.split(/\r?\n/);
+  const root: TomlObject = {};
+  let currentPath: string[] = [];
+
+  for (const rawLine of lines) {
+    const line = rawLine.trim();
+    if (!line || line.startsWith("#")) {
+      continue;
+    }
+
+    if (line.startsWith("[") && line.endsWith("]")) {
+      const sectionName = line.slice(1, -1).trim();
+      currentPath = sectionName
+        ? sectionName
+            .split(".")
+            .map((part) => part.trim())
+            .filter(Boolean)
+        : [];
+      continue;
+    }
+
+    const eqIndex = line.indexOf("=");
+    if (eqIndex === -1) {
+      continue;
+    }
+
+    const key = line.slice(0, eqIndex).trim();
+    const valueRaw = line.slice(eqIndex + 1).trim();
+    if (!key) {
+      continue;
+    }
+
+    let value = valueRaw;
+    if (
+      (value.startsWith('"') && value.endsWith('"')) ||
+      (value.startsWith("'") && value.endsWith("'"))
+    ) {
+      value = value.slice(1, -1);
+    }
+
+    let cursor: TomlObject = root;
+    for (const section of currentPath) {
+      if (!cursor[section] || typeof cursor[section] === "string") {
+        cursor[section] = {};
+      }
+      cursor = cursor[section] as TomlObject;
+    }
+
+    cursor[key] = value;
+  }
+
+  return root;
+}
+
+function getValue(target: TomlObject, key: string): string | undefined {
+  const parts = key.split(".");
+  let cursor: TomlValue = target;
+  for (const part of parts) {
+    if (typeof cursor !== "object" || cursor === null) {
+      return undefined;
+    }
+    cursor = (cursor as TomlObject)[part];
+    if (cursor === undefined) {
+      return undefined;
+    }
+  }
+  return typeof cursor === "string" ? cursor : undefined;
+}
+
+function detectLocale(): Locale {
+  if (typeof window === "undefined") {
+    return DEFAULT_LOCALE;
+  }
+
+  const stored = window.localStorage.getItem(LOCALE_STORAGE_KEY);
+  if (stored && isSupportedLocale(stored)) {
+    return stored;
+  }
+
+  const pathLocale = window.location.pathname.split("/")[1];
+  if (pathLocale && isSupportedLocale(pathLocale)) {
+    return pathLocale;
+  }
+
+  const browserLang = window.navigator.language.toLowerCase();
+  if (browserLang.startsWith("ko")) {
+    return "ko";
+  }
+
+  return DEFAULT_LOCALE;
+}
+
+function formatTemplate(
+  template: string,
+  vars?: Record<string, string | number>,
+  options?: TranslatorOptions,
+): string {
+  const normalizedTemplate = options?.normalizeEscapedNewlines
+    ? template.replace(/\\n/g, "\n")
+    : template;
+
+  if (!vars) {
+    return normalizedTemplate;
+  }
+
+  return normalizedTemplate.replace(/\{\{\s*(\w+)\s*\}\}/g, (match, key) => {
+    const value = vars[key];
+    if (value === undefined || value === null) {
+      return match;
+    }
+    return String(value);
+  });
+}
+
+export function createTomlTranslator(
+  input: TranslatorInput,
+  options?: TranslatorOptions,
+) {
+  const translations: Record<Locale, TomlObject> = {
+    ko: input.ko
+      .map((raw) => parseToml(raw))
+      .reduce<TomlObject>((merged, current) => mergeTomlObjects(merged, current), {}),
+    en: input.en
+      .map((raw) => parseToml(raw))
+      .reduce<TomlObject>((merged, current) => mergeTomlObjects(merged, current), {}),
+  };
+
+  return function t(
+    key: string,
+    fallback?: string,
+    vars?: Record<string, string | number>,
+  ): string {
+    const locale = detectLocale();
+    const value = getValue(translations[locale], key);
+    if (value && value.length > 0) {
+      return formatTemplate(value, vars, options);
+    }
+    return formatTemplate(fallback ?? key, vars, options);
+  };
+}
diff --git a/common/core/i18n/types.ts b/common/core/i18n/types.ts
new file mode 100644
index 00000000..b8db5ec3
--- /dev/null
+++ b/common/core/i18n/types.ts
@@ -0,0 +1,20 @@
+export const LOCALE_STORAGE_KEY = "locale";
+export const DEFAULT_LOCALE = "ko";
+export const SUPPORTED_LOCALES = ["ko", "en"] as const;
+
+export type Locale = (typeof SUPPORTED_LOCALES)[number];
+
+export type TomlValue = string | TomlObject;
+
+export interface TomlObject {
+  [key: string]: TomlValue;
+}
+
+export interface TranslatorOptions {
+  normalizeEscapedNewlines?: boolean;
+}
+
+export interface TranslatorInput {
+  en: string[];
+  ko: string[];
+}
diff --git a/common/core/query/.gitkeep b/common/core/query/.gitkeep
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/common/core/query/.gitkeep
@@ -0,0 +1 @@
+
diff --git a/common/core/session/.gitkeep b/common/core/session/.gitkeep
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/common/core/session/.gitkeep
@@ -0,0 +1 @@
+
diff --git a/common/core/utils/.gitkeep b/common/core/utils/.gitkeep
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/common/core/utils/.gitkeep
@@ -0,0 +1 @@
+
diff --git a/common/locales/en.toml b/common/locales/en.toml
new file mode 100644
index 00000000..73d530b6
--- /dev/null
+++ b/common/locales/en.toml
@@ -0,0 +1,77 @@
+[msg.common]
+error = "Error"
+loading = "Loading..."
+no_description = "No Description."
+parsing = "Parsing data..."
+requesting = "Requesting..."
+saving = "Saving..."
+unknown_error = "unknown error"
+
+[ui.common]
+add = "Add"
+all = "All"
+admin_only = "Admin Only"
+assign = "Assign"
+back = "Back"
+back_to_login = "Back to login"
+cancel = "Cancel"
+change_file = "Change File"
+clear_search = "Clear Search"
+close = "Close"
+collapse = "Collapse"
+confirm = "Confirm"
+copy = "Copy"
+create = "Create"
+delete = "Delete"
+details = "Details"
+disabled = "Disabled"
+edit = "Edit"
+enabled = "Enabled"
+export = "Export"
+fail = "Fail"
+go_home = "Go Home"
+view = "View"
+hyphen = "-"
+manage = "Manage"
+na = "N/A"
+never = "Never"
+next = "Next"
+none = "None"
+page_of = "Page {{page}} of {{total}}"
+prev = "Prev"
+previous = "Previous"
+qr = "QR"
+reset = "Reset"
+read_only = "Read Only"
+refresh = "Refresh"
+remove = "Remove"
+resend = "Resend"
+retry = "Retry"
+save = "Save"
+search = "Search"
+select = "Select"
+select_file = "Select File"
+select_placeholder = "Select Placeholder"
+show_more = "Show More"
+language = "Language"
+language_ko = "Korean"
+language_en = "English"
+success = "Success"
+theme_dark = "Dark"
+theme_light = "Light"
+theme_toggle = "Theme Toggle"
+unknown = "Unknown"
+
+[ui.common.badge]
+admin_only = "Admin only"
+command_only = "Command only"
+system = "System"
+
+[ui.common.status]
+active = "Active"
+blocked = "Blocked"
+failure = "Failure"
+inactive = "Inactive"
+ok = "Ok"
+pending = "Pending"
+success = "Success"
diff --git a/common/locales/ko.toml b/common/locales/ko.toml
new file mode 100644
index 00000000..f5cf7c74
--- /dev/null
+++ b/common/locales/ko.toml
@@ -0,0 +1,77 @@
+[msg.common]
+error = "오류가 발생했습니다."
+loading = "로딩 중..."
+no_description = "설명이 없습니다."
+parsing = "데이터 파싱 중..."
+requesting = "요청 중..."
+saving = "저장 중..."
+unknown_error = "알 수 없는 오류"
+
+[ui.common]
+add = "추가"
+all = "전체"
+admin_only = "관리자 전용"
+assign = "할당"
+back = "돌아가기"
+back_to_login = "로그인으로 돌아가기"
+cancel = "취소"
+change_file = "파일 변경"
+clear_search = "검색 초기화"
+close = "닫기"
+collapse = "접기"
+confirm = "확인"
+copy = "복사"
+create = "생성"
+delete = "삭제"
+details = "상세정보"
+disabled = "사용 안 함"
+edit = "편집"
+enabled = "사용"
+export = "내보내기"
+fail = "실패"
+go_home = "홈으로"
+view = "보기"
+hyphen = "-"
+manage = "관리"
+na = "N/A"
+never = "Never"
+next = "다음"
+none = "없음"
+page_of = "Page {{page}} of {{total}}"
+prev = "이전"
+previous = "이전"
+qr = "QR"
+reset = "초기화"
+read_only = "읽기 전용"
+refresh = "새로고침"
+remove = "제외"
+resend = "재발송"
+retry = "다시 시도"
+save = "저장"
+search = "검색"
+select = "선택"
+select_file = "파일 선택"
+select_placeholder = "선택하세요"
+show_more = "+ 더보기"
+language = "언어"
+language_ko = "한국어"
+language_en = "English"
+success = "성공"
+theme_dark = "Dark"
+theme_light = "Light"
+theme_toggle = "테마 전환"
+unknown = "Unknown"
+
+[ui.common.badge]
+admin_only = "Admin only"
+command_only = "Command only"
+system = "System"
+
+[ui.common.status]
+active = "활성"
+blocked = "차단됨"
+failure = "실패"
+inactive = "비활성"
+ok = "정상"
+pending = "준비 중"
+success = "성공"
diff --git a/common/locales/template.toml b/common/locales/template.toml
new file mode 100644
index 00000000..1cb9e149
--- /dev/null
+++ b/common/locales/template.toml
@@ -0,0 +1,77 @@
+[msg.common]
+error = ""
+loading = ""
+no_description = ""
+parsing = ""
+requesting = ""
+saving = ""
+unknown_error = ""
+
+[ui.common]
+add = ""
+all = ""
+admin_only = ""
+assign = ""
+back = ""
+back_to_login = ""
+cancel = ""
+change_file = ""
+clear_search = ""
+close = ""
+collapse = ""
+confirm = ""
+copy = ""
+create = ""
+delete = ""
+details = ""
+disabled = ""
+edit = ""
+enabled = ""
+export = ""
+fail = ""
+go_home = ""
+view = ""
+hyphen = ""
+manage = ""
+na = ""
+never = ""
+next = ""
+none = ""
+page_of = ""
+prev = ""
+previous = ""
+qr = ""
+reset = ""
+read_only = ""
+refresh = ""
+remove = ""
+resend = ""
+retry = ""
+save = ""
+search = ""
+select = ""
+select_file = ""
+select_placeholder = ""
+show_more = ""
+language = ""
+language_ko = ""
+language_en = ""
+success = ""
+theme_dark = ""
+theme_light = ""
+theme_toggle = ""
+unknown = ""
+
+[ui.common.badge]
+admin_only = ""
+command_only = ""
+system = ""
+
+[ui.common.status]
+active = ""
+blocked = ""
+failure = ""
+inactive = ""
+ok = ""
+pending = ""
+success = ""
diff --git a/common/shell/.gitkeep b/common/shell/.gitkeep
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/common/shell/.gitkeep
@@ -0,0 +1 @@
+
diff --git a/common/theme/.gitkeep b/common/theme/.gitkeep
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/common/theme/.gitkeep
@@ -0,0 +1 @@
+
diff --git a/common/ui/.gitkeep b/common/ui/.gitkeep
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/common/ui/.gitkeep
@@ -0,0 +1 @@
+