Enhance internationalization support by integrating language selection for school names, updating UI components for localization, and revising documentation. Implement locale-aware formatting for dates and strings, ensuring a seamless user experience in both Russian and English. Update tests to cover new language features.

2026-08-18 12:43:14 +03:00
parent b9ddc018d3
commit cc9efca891
24 changed files with 640 additions and 140 deletions
@@ -13,7 +13,7 @@ way; this file is *how to work in them*.
 | what the socket carries | `src/HSchool.Protocol` **and** `src/HSchool.Client/src/net/protocol.ts` **and** `docs/protocol.md` |
 | connection handling, the loop | `src/HSchool.Server` |
 | what runs locally | `src/HSchool.AppHost/AppHost.cs` |
-| screens, dialogs, formatting | `src/HSchool.Client/src` |
+| screens, dialogs, formatting, UI language | `src/HSchool.Client/src` |

 ## Commands

@@ -85,10 +85,11 @@ say so explicitly in the change description.

 - `strict` is on, no `any`, no non-null `!` assertions.
 - Relative imports carry the `.ts` extension (bundler resolution is configured for it).
- Modules stay thin: `net/` speaks to the server, `ui/` renders, `format/` formats, `main.ts`
-  wires them together.
+- Modules stay thin: `net/` speaks to the server, `ui/` renders, `format/` formats, `i18n/`
+  holds the RU/EN dictionaries, `main.ts` wires them together.
 - No framework, plain DOM. `ui/dom.ts` is the whole helper budget.
- UI strings are Russian; game dates are formatted through `format/gameTime.ts`, never inline.
+- UI strings go through `t(...)` in `i18n/strings.ts`, never inline. Game dates go through
+  `format/gameTime.ts`, which follows the active locale.

 **Both**

@@ -105,7 +106,8 @@ say so explicitly in the change description.
 - Those tests also share one server, so schools survive between them: start each test by clearing
  the list (`SchoolApiTests.ResetAsync`) instead of assuming it is empty.
 - The screens have no unit tests — a DOM environment would cost a dependency the project does not
-  have. Verify UI changes by running the app.
+  have. Verify UI changes by running the app. Dictionaries and date formatting are covered in
+  Vitest (`i18n/strings.test.ts`, `format/gameTime.test.ts`).

 ## Dependencies

@@ -41,7 +41,8 @@ rather than guessing.
 ## What you can do

 - **Main menu** — every school as a card with its name and its current in-game date and time,
-  ticking live. Deleting one asks for confirmation first.
+  ticking live. Deleting one asks for confirmation first. The footer switches the UI between
+  Russian and English; the choice is remembered in the browser.
 - **Create a school** — type a name or roll a random one, pick a start date (3 April 2012, 06:00
  by default). At six schools the create button is disabled and says why.
 - **Inside a school** — the date, time and weekday of the game calendar, play/pause and the
@@ -81,7 +82,7 @@ dotnet test
 npm --prefix src/HSchool.Client test
 ```

-Vitest covers the client codec and the calendar formatting.
+Vitest covers the client codec, the calendar formatting and the RU/EN dictionaries.

 ## Layout

@@ -44,6 +44,10 @@ Everything the main menu needs in one request.

 `{ "name": "Лицей «Северная»" }` — a suggestion that is not already taken.

+Optional `?lang=en` draws from the English word list (`Northern Academy`); any other value, or
+none, stays Russian. The client sends the active UI language. Names the player types are not
+translated — they are saved as written.
+
 ### `POST /api/schools`

 Body: `{ "name": "Гимназия №14", "startDate": "2012-04-03T06:00:00Z" }`
@@ -9,8 +9,8 @@
  <body>
    <main id="app"></main>
    <footer id="status">
-      <span data-status="connection">подключение…</span>
-      <span data-status="ping">-- мс</span>
+      <span data-status="connection"></span>
+      <span data-status="ping"></span>
    </footer>
    <script type="module" src="/src/main.ts"></script>
  </body>
@@ -1,4 +1,5 @@
-import { describe, expect, it } from 'vitest';
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+import { getLocale, setLocale } from '../i18n/locale.ts';
 import {
  formatGameDate,
  formatGameDateTime,
@@ -10,6 +11,10 @@ import {

 // The default start of a new school: 3 April 2012, 06:00 — a Tuesday.
 const START = new Date(Date.UTC(2012, 3, 3, 6, 0, 0));
+const initial = getLocale();
+
+beforeEach(() => setLocale('ru'));
+afterEach(() => setLocale(initial));

 describe('game time formatting', () => {
  it('shows the time of day in 24-hour form', () => {
@@ -30,6 +35,15 @@ describe('game time formatting', () => {
    expect(formatGameDateTime(START)).toContain('06:00');
  });

+  it('formats the same instant in English when the locale is en', () => {
+    setLocale('en');
+
+    expect(formatGameWeekday(START)).toBe('Tuesday');
+    expect(formatGameDate(START)).toContain('April');
+    expect(formatGameDateTime(START)).toContain('03/04/2012');
+    expect(formatGameTimeOfDay(START)).toBe('06:00');
+  });
+
  it('reads the calendar in UTC, so the school day does not shift with the viewer', () => {
    // Just before midnight UTC: any local-time formatting would land on the 4th.
    const lateEvening = new Date(Date.UTC(2012, 3, 3, 23, 30, 0));
@@ -6,53 +6,76 @@
 * whatever offset they happen to live in.
 */

-const LOCALE = 'ru-RU';
+import { intlTag, onLocaleChange } from '../i18n/locale.ts';
+
 const UTC = 'UTC';

-const dateFormat = new Intl.DateTimeFormat(LOCALE, {
-  timeZone: UTC,
-  day: 'numeric',
-  month: 'long',
-  year: 'numeric',
+interface Formats {
+  readonly date: Intl.DateTimeFormat;
+  readonly time: Intl.DateTimeFormat;
+  readonly weekday: Intl.DateTimeFormat;
+  readonly short: Intl.DateTimeFormat;
+}
+
+let cached: { tag: string; formats: Formats } | null = null;
+
+function formats(): Formats {
+  const tag = intlTag();
+  if (cached?.tag === tag) {
+    return cached.formats;
+  }
+
+  const next: Formats = {
+    date: new Intl.DateTimeFormat(tag, {
+      timeZone: UTC,
+      day: 'numeric',
+      month: 'long',
+      year: 'numeric',
+    }),
+    time: new Intl.DateTimeFormat(tag, {
+      timeZone: UTC,
+      hour: '2-digit',
+      minute: '2-digit',
+      hour12: false,
+    }),
+    weekday: new Intl.DateTimeFormat(tag, { timeZone: UTC, weekday: 'long' }),
+    short: new Intl.DateTimeFormat(tag, {
+      timeZone: UTC,
+      day: '2-digit',
+      month: '2-digit',
+      year: 'numeric',
+      hour: '2-digit',
+      minute: '2-digit',
+      hour12: false,
+    }),
+  };
+
+  cached = { tag, formats: next };
+  return next;
+}
+
+onLocaleChange(() => {
+  cached = null;
 });

-const timeFormat = new Intl.DateTimeFormat(LOCALE, {
-  timeZone: UTC,
-  hour: '2-digit',
-  minute: '2-digit',
-  hour12: false,
-});
-
-const weekdayFormat = new Intl.DateTimeFormat(LOCALE, { timeZone: UTC, weekday: 'long' });
-
-const shortFormat = new Intl.DateTimeFormat(LOCALE, {
-  timeZone: UTC,
-  day: '2-digit',
-  month: '2-digit',
-  year: 'numeric',
-  hour: '2-digit',
-  minute: '2-digit',
-  hour12: false,
-});
-
-/** "3 апреля 2012 г." */
+/** "3 апреля 2012 г." / "3 April 2012" */
 export function formatGameDate(date: Date): string {
-  return dateFormat.format(date);
+  return formats().date.format(date);
 }

 /** "06:00" */
 export function formatGameTimeOfDay(date: Date): string {
-  return timeFormat.format(date);
+  return formats().time.format(date);
 }

-/** "вторник" */
+/** "вторник" / "Tuesday" */
 export function formatGameWeekday(date: Date): string {
-  return weekdayFormat.format(date);
+  return formats().weekday.format(date);
 }

-/** "03.04.2012, 06:00" — the compact form the school cards use. */
+/** Compact form the school cards use — day-month-year in both languages. */
 export function formatGameDateTime(date: Date): string {
-  return shortFormat.format(date);
+  return formats().short.format(date);
 }

 /** Splits an ISO instant into the `<input type="date">` and `<input type="time">` values it needs. */
@@ -0,0 +1,75 @@
+/** The two UI languages. English dates use en-GB so day-month-year matches the Russian order. */
+export type Locale = 'ru' | 'en';
+
+export const LOCALES = ['ru', 'en'] as const;
+
+const STORAGE_KEY = 'h-school.locale';
+
+let current: Locale = detect();
+const listeners = new Set<() => void>();
+
+function detect(): Locale {
+  const stored = readStored();
+  if (stored !== null) {
+    return stored;
+  }
+
+  const language = typeof navigator === 'undefined' ? '' : navigator.language.toLowerCase();
+  return language.startsWith('ru') ? 'ru' : 'en';
+}
+
+function readStored(): Locale | null {
+  try {
+    const value = globalThis.localStorage?.getItem(STORAGE_KEY);
+    return value === 'ru' || value === 'en' ? value : null;
+  } catch {
+    return null;
+  }
+}
+
+function persist(locale: Locale): void {
+  try {
+    globalThis.localStorage?.setItem(STORAGE_KEY, locale);
+  } catch {
+    // Private mode, or tests without a store — the in-memory value still changes.
+  }
+}
+
+function applyToDocument(locale: Locale): void {
+  if (typeof document === 'undefined') {
+    return;
+  }
+
+  document.documentElement.lang = locale;
+}
+
+applyToDocument(current);
+
+export function getLocale(): Locale {
+  return current;
+}
+
+/** BCP 47 tag for `Intl` formatters. */
+export function intlTag(locale: Locale = current): 'ru-RU' | 'en-GB' {
+  return locale === 'en' ? 'en-GB' : 'ru-RU';
+}
+
+export function setLocale(locale: Locale): void {
+  if (locale === current) {
+    return;
+  }
+
+  current = locale;
+  persist(locale);
+  applyToDocument(locale);
+
+  for (const listener of listeners) {
+    listener();
+  }
+}
+
+/** Returns an unsubscribe function. */
+export function onLocaleChange(listener: () => void): () => void {
+  listeners.add(listener);
+  return () => listeners.delete(listener);
+}
@@ -0,0 +1,41 @@
+import { afterEach, describe, expect, it } from 'vitest';
+import { getLocale, setLocale } from './locale.ts';
+import { schoolWord, t } from './strings.ts';
+
+const initial = getLocale();
+
+afterEach(() => setLocale(initial));
+
+describe('t', () => {
+  it('returns the Russian string for the active locale', () => {
+    setLocale('ru');
+    expect(t('createSchool')).toBe('Создать школу');
+  });
+
+  it('returns the English string after a switch', () => {
+    setLocale('en');
+    expect(t('createSchool')).toBe('Create school');
+  });
+
+  it('interpolates placeholders', () => {
+    setLocale('en');
+    expect(t('schoolCount', { current: 2, max: 6 })).toBe('Schools: 2 of 6.');
+  });
+});
+
+describe('schoolWord', () => {
+  it('uses the Russian one/few/many forms', () => {
+    setLocale('ru');
+    expect(schoolWord(1)).toBe('школа');
+    expect(schoolWord(2)).toBe('школы');
+    expect(schoolWord(5)).toBe('школ');
+    expect(schoolWord(21)).toBe('школа');
+  });
+
+  it('uses the English one/other forms', () => {
+    setLocale('en');
+    expect(schoolWord(1)).toBe('school');
+    expect(schoolWord(2)).toBe('schools');
+    expect(schoolWord(5)).toBe('schools');
+  });
+});
@@ -0,0 +1,137 @@
+import { getLocale, intlTag, type Locale } from './locale.ts';
+
+const ru = {
+  statusConnecting: 'подключение…',
+  statusConnected: 'сервер на связи',
+  statusReconnecting: 'переподключение…',
+  statusClosed: 'соединение закрыто',
+  pingMs: '{ms} мс',
+  pingPlaceholder: '-- мс',
+  language: 'Язык',
+
+  schoolsTitle: 'Школы',
+  createSchool: 'Создать школу',
+  emptySchools: 'Пока ни одной школы. Создайте первую.',
+  loadSchoolsFailed: 'Не удалось загрузить список школ. Проверьте соединение с сервером.',
+  createDisabledTitle: 'Удалите одну из школ, чтобы создать новую',
+  schoolCount: 'Школ: {current} из {max}.',
+  schoolLimitReached: 'Достигнут лимит: {max} {schoolWord}. Удалите одну, чтобы создать новую.',
+
+  deleteSchool: 'Удалить',
+  deleteSchoolTitle: 'Удалить школу?',
+  deleteSchoolMessage: '«{name}» будет удалена без возможности восстановления.',
+  deleteFailed: 'Не удалось удалить «{name}».',
+  paused: '⏸ на паузе',
+
+  newSchool: 'Новая школа',
+  schoolName: 'Название',
+  schoolNamePlaceholder: 'Название школы',
+  randomName: 'Случайное',
+  randomNameTitle: 'Придумать название',
+  gameStart: 'Начало игры',
+  create: 'Создать',
+  cancel: 'Отмена',
+  confirm: 'Подтвердить',
+  randomNameFailed: 'Не удалось получить название с сервера.',
+  startDateRequired: 'Укажите дату и время начала.',
+  serverUnavailable: 'Сервер недоступен. Попробуйте ещё раз.',
+  errorSchoolLimit: 'Достигнут лимит школ — удалите одну, чтобы создать новую.',
+  errorInvalidName: 'Название должно быть от 1 до 40 символов.',
+  errorInvalidStartDate: 'Дата начала вне допустимого диапазона.',
+
+  backToMenu: '← В главное меню',
+  emptySchoolHint: 'Школа пока пуста — здесь появится сама игра.',
+  pause: 'Пауза',
+  resume: 'Продолжить',
+} as const;
+
+type Messages = { [K in keyof typeof ru]: string };
+
+const en: Messages = {
+  statusConnecting: 'connecting…',
+  statusConnected: 'connected',
+  statusReconnecting: 'reconnecting…',
+  statusClosed: 'connection closed',
+  pingMs: '{ms} ms',
+  pingPlaceholder: '-- ms',
+  language: 'Language',
+
+  schoolsTitle: 'Schools',
+  createSchool: 'Create school',
+  emptySchools: 'No schools yet. Create the first one.',
+  loadSchoolsFailed: 'Could not load the school list. Check the connection to the server.',
+  createDisabledTitle: 'Delete a school to create a new one',
+  schoolCount: 'Schools: {current} of {max}.',
+  schoolLimitReached: 'Limit reached: {max} {schoolWord}. Delete one to create another.',
+
+  deleteSchool: 'Delete',
+  deleteSchoolTitle: 'Delete this school?',
+  deleteSchoolMessage: '"{name}" will be deleted permanently.',
+  deleteFailed: 'Could not delete "{name}".',
+  paused: '⏸ paused',
+
+  newSchool: 'New school',
+  schoolName: 'Name',
+  schoolNamePlaceholder: 'School name',
+  randomName: 'Random',
+  randomNameTitle: 'Suggest a name',
+  gameStart: 'Game start',
+  create: 'Create',
+  cancel: 'Cancel',
+  confirm: 'Confirm',
+  randomNameFailed: 'Could not fetch a name from the server.',
+  startDateRequired: 'Enter a start date and time.',
+  serverUnavailable: 'The server is unavailable. Try again.',
+  errorSchoolLimit: 'School limit reached — delete one to create another.',
+  errorInvalidName: 'The name must be 1 to 40 characters.',
+  errorInvalidStartDate: 'The start date is outside the allowed range.',
+
+  backToMenu: '← Main menu',
+  emptySchoolHint: 'The school is empty for now — the game itself will appear here.',
+  pause: 'Pause',
+  resume: 'Resume',
+};
+
+const catalogs: Record<Locale, Messages> = { ru, en };
+
+export type MessageKey = keyof Messages;
+
+export function t(key: MessageKey, vars?: Record<string, string | number>): string {
+  let text: string = catalogs[getLocale()][key];
+
+  if (vars !== undefined) {
+    for (const [name, value] of Object.entries(vars)) {
+      text = text.replaceAll(`{${name}}`, String(value));
+    }
+  }
+
+  return text;
+}
+
+interface PluralForms {
+  readonly one: string;
+  readonly few?: string;
+  readonly many?: string;
+  readonly other: string;
+}
+
+const schoolWordForms: Record<Locale, PluralForms> = {
+  ru: { one: 'школа', few: 'школы', many: 'школ', other: 'школ' },
+  en: { one: 'school', other: 'schools' },
+};
+
+export function schoolWord(count: number): string {
+  const forms = schoolWordForms[getLocale()];
+  const rule = new Intl.PluralRules(intlTag()).select(count);
+
+  switch (rule) {
+    case 'one':
+      return forms.one;
+    case 'few':
+      return forms.few ?? forms.other;
+    case 'many':
+      return forms.many ?? forms.other;
+    default:
+      return forms.other;
+  }
+}
@@ -1,23 +1,31 @@
 import { GameConnection, gameSocketUrl, type ConnectionStatus } from './net/connection.ts';
+import { onLocaleChange } from './i18n/locale.ts';
+import { t, type MessageKey } from './i18n/strings.ts';
 import { GameScreen } from './ui/gameScreen.ts';
+import { localeSwitch } from './ui/localeSwitch.ts';
 import { MainMenu } from './ui/mainMenu.ts';
 import type { School } from './net/api.ts';
 import './style.css';

-const STATUS_LABELS: Record<ConnectionStatus, string> = {
-  connecting: 'подключение…',
-  connected: 'сервер на связи',
-  reconnecting: 'переподключение…',
-  closed: 'соединение закрыто',
+const STATUS_KEYS: Record<ConnectionStatus, MessageKey> = {
+  connecting: 'statusConnecting',
+  connected: 'statusConnected',
+  reconnecting: 'statusReconnecting',
+  closed: 'statusClosed',
 };

 /** Wires the two screens to one WebSocket connection. */
 function bootstrap(): void {
  const app = requireElement('#app');
+  const footer = requireElement('#status');
  const statusLabel = document.querySelector<HTMLElement>('[data-status="connection"]');
  const pingLabel = document.querySelector<HTMLElement>('[data-status="ping"]');

+  footer.prepend(localeSwitch());
+
  let openSchool: School | null = null;
+  let connectionStatus: ConnectionStatus = 'connecting';
+  let lastPingMs: number | null = null;

  const menu = new MainMenu({ onOpenSchool: (school) => enterSchool(school) });
  const game = new GameScreen({
@@ -28,9 +36,8 @@ function bootstrap(): void {

  const connection = new GameConnection(gameSocketUrl(), {
    onStatus: (status) => {
-      if (statusLabel !== null) {
-        statusLabel.textContent = STATUS_LABELS[status];
-      }
+      connectionStatus = status;
+      paintChrome();
    },
    onClock: (clock) => {
      if (openSchool?.id === clock.schoolId) {
@@ -44,12 +51,22 @@ function bootstrap(): void {
      }
    },
    onLatency: (rttMs) => {
-      if (pingLabel !== null) {
-        pingLabel.textContent = `${Math.round(rttMs)} мс`;
-      }
+      lastPingMs = rttMs;
+      paintChrome();
    },
  });

+  function paintChrome(): void {
+    if (statusLabel !== null) {
+      statusLabel.textContent = t(STATUS_KEYS[connectionStatus]);
+    }
+
+    if (pingLabel !== null) {
+      pingLabel.textContent =
+        lastPingMs === null ? t('pingPlaceholder') : t('pingMs', { ms: Math.round(lastPingMs) });
+    }
+  }
+
  function enterSchool(school: School): void {
    openSchool = school;
    menu.stop();
@@ -69,6 +86,13 @@ function bootstrap(): void {
    menu.start();
  }

+  onLocaleChange(() => {
+    paintChrome();
+    menu.localize();
+    game.localize();
+  });
+
+  paintChrome();
  connection.connect();
  showMenu();

@@ -34,8 +34,10 @@ export async function fetchSchools(): Promise<SchoolsResponse> {
  return request<SchoolsResponse>('/api/schools');
 }

-export async function fetchRandomName(): Promise<string> {
-  const response = await request<{ name: string }>('/api/schools/random-name');
+export async function fetchRandomName(lang: string): Promise<string> {
+  const response = await request<{ name: string }>(
+    `/api/schools/random-name?lang=${encodeURIComponent(lang)}`,
+  );
  return response.name;
 }

@@ -34,11 +34,39 @@ body {
  right: 16px;
  bottom: 12px;
  display: flex;
+  align-items: center;
  gap: 14px;
  font-size: 12px;
  color: var(--text-muted);
 }

+.locale-switch {
+  display: flex;
+  gap: 4px;
+}
+
+.locale-switch__button {
+  padding: 3px 8px;
+  border: 1px solid var(--border);
+  border-radius: 6px;
+  background: transparent;
+  color: var(--text-muted);
+  font: inherit;
+  font-size: 11px;
+  letter-spacing: 0.04em;
+  cursor: pointer;
+}
+
+.locale-switch__button:hover {
+  border-color: var(--accent);
+  color: var(--text);
+}
+
+.locale-switch__button[aria-pressed='true'] {
+  border-color: var(--accent);
+  color: var(--accent);
+}
+
 /* Screens */

 .screen__header {
@@ -1,3 +1,4 @@
+import { t } from '../i18n/strings.ts';
 import { el } from './dom.ts';
 import { Modal } from './modal.ts';

@@ -17,7 +18,7 @@ export function confirmDialog(options: ConfirmOptions): Promise<boolean> {
  const confirmButton = el('button', {
    class: options.danger === true ? 'button button--danger' : 'button button--primary',
    type: 'button',
-    text: options.confirmLabel ?? 'Подтвердить',
+    text: options.confirmLabel ?? t('confirm'),
    onClick: () => modal.close(true),
  });

@@ -30,7 +31,7 @@ export function confirmDialog(options: ConfirmOptions): Promise<boolean> {
      el('button', {
        class: 'button',
        type: 'button',
-        text: options.cancelLabel ?? 'Отмена',
+        text: options.cancelLabel ?? t('cancel'),
        onClick: () => modal.close(false),
      }),
      confirmButton,
@@ -1,5 +1,6 @@
 import { ApiError, type School } from '../net/api.ts';
 import { fromDateAndTimeInputs, toDateAndTimeInputs } from '../format/gameTime.ts';
+import { t } from '../i18n/strings.ts';
 import { el } from './dom.ts';
 import { Modal } from './modal.ts';

@@ -20,7 +21,7 @@ export function createSchoolDialog(options: CreateSchoolOptions): Promise<School

  const nameInput = el('input', { class: 'input', type: 'text' });
  nameInput.maxLength = 40;
-  nameInput.placeholder = 'Название школы';
+  nameInput.placeholder = t('schoolNamePlaceholder');
  nameInput.required = true;

  const dateInput = el('input', { class: 'input', type: 'date' });
@@ -37,11 +38,11 @@ export function createSchoolDialog(options: CreateSchoolOptions): Promise<School
  const randomButton = el('button', {
    class: 'button',
    type: 'button',
-    text: 'Случайное',
-    title: 'Придумать название',
+    text: t('randomName'),
+    title: t('randomNameTitle'),
  });

-  const submitButton = el('button', { class: 'button button--primary', type: 'submit', text: 'Создать' });
+  const submitButton = el('button', { class: 'button button--primary', type: 'submit', text: t('create') });

  const form = el(
    'form',
@@ -49,20 +50,20 @@ export function createSchoolDialog(options: CreateSchoolOptions): Promise<School
    el(
      'label',
      { class: 'field' },
-      el('span', { class: 'field__label', text: 'Название' }),
+      el('span', { class: 'field__label', text: t('schoolName') }),
      el('div', { class: 'field__row' }, nameInput, randomButton),
    ),
    el(
      'div',
      { class: 'field' },
-      el('span', { class: 'field__label', text: 'Начало игры' }),
+      el('span', { class: 'field__label', text: t('gameStart') }),
      el('div', { class: 'field__row' }, dateInput, timeInput),
    ),
    error,
    el(
      'div',
      { class: 'dialog__actions' },
-      el('button', { class: 'button', type: 'button', text: 'Отмена', onClick: () => modal.close(null) }),
+      el('button', { class: 'button', type: 'button', text: t('cancel'), onClick: () => modal.close(null) }),
      submitButton,
    ),
  );
@@ -92,7 +93,7 @@ export function createSchoolDialog(options: CreateSchoolOptions): Promise<School
        nameInput.value = name;
        error.hidden = true;
      })
-      .catch(() => showError('Не удалось получить название с сервера.'))
+      .catch(() => showError(t('randomNameFailed')))
      .finally(() => setBusy(false));
  });

@@ -104,7 +105,7 @@ export function createSchoolDialog(options: CreateSchoolOptions): Promise<School

    const startDate = fromDateAndTimeInputs(dateInput.value, timeInput.value);
    if (startDate === null) {
-      showError('Укажите дату и время начала.');
+      showError(t('startDateRequired'));
      return;
    }

@@ -118,23 +119,23 @@ export function createSchoolDialog(options: CreateSchoolOptions): Promise<School
      });
  });

-  modal.element.append(el('h2', { class: 'dialog__title', text: 'Новая школа' }), form);
+  modal.element.append(el('h2', { class: 'dialog__title', text: t('newSchool') }), form);

  return modal.open(nameInput);
 }

 function describe(reason: unknown): string {
  if (!(reason instanceof ApiError)) {
-    return 'Сервер недоступен. Попробуйте ещё раз.';
+    return t('serverUnavailable');
  }

  switch (reason.code) {
    case 'school-limit-reached':
-      return 'Достигнут лимит школ — удалите одну, чтобы создать новую.';
+      return t('errorSchoolLimit');
    case 'invalid-name':
-      return 'Название должно быть от 1 до 40 символов.';
+      return t('errorInvalidName');
    case 'invalid-start-date':
-      return 'Дата начала вне допустимого диапазона.';
+      return t('errorInvalidStartDate');
    default:
      return reason.message;
  }
@@ -1,5 +1,6 @@
 import { CLOCK_SPEEDS, type ClockMessage } from '../net/protocol.ts';
 import { formatGameDate, formatGameTimeOfDay, formatGameWeekday } from '../format/gameTime.ts';
+import { t } from '../i18n/strings.ts';
 import type { School } from '../net/api.ts';
 import { el } from './dom.ts';

@@ -17,14 +18,18 @@ const SPEED_LABELS = ['×½', '×1', '×2', '×3', '×4'];
 */
 export class GameScreen {
  private readonly root = el('section', { class: 'screen game' });
+  private readonly backButton = el('button', { class: 'button', type: 'button' });
  private readonly schoolName = el('h1', { class: 'screen__title' });
  private readonly time = el('p', { class: 'clock__time', text: '--:--' });
  private readonly date = el('p', { class: 'clock__date' });
  private readonly weekday = el('p', { class: 'clock__weekday' });
+  private readonly emptyHint = el('p', { class: 'hint' });
  private readonly playPauseButton = el('button', { class: 'button button--icon', type: 'button', text: '▶' });
  private readonly speedButtons: HTMLButtonElement[];

  private running = false;
+  private lastGameTime: Date | null = null;
+  private lastSpeedIndex = 0;

  constructor(options: GameScreenOptions) {
    this.speedButtons = CLOCK_SPEEDS.map((_, index) =>
@@ -36,15 +41,11 @@ export class GameScreen {
      }),
    );

+    this.backButton.addEventListener('click', options.onLeave);
    this.playPauseButton.addEventListener('click', () => options.onSetRunning(!this.running));

    this.root.append(
-      el(
-        'header',
-        { class: 'screen__header' },
-        el('button', { class: 'button', type: 'button', text: '← В главное меню', onClick: options.onLeave }),
-        this.schoolName,
-      ),
+      el('header', { class: 'screen__header' }, this.backButton, this.schoolName),
      el(
        'div',
        { class: 'clock' },
@@ -53,14 +54,27 @@ export class GameScreen {
        this.weekday,
        el('div', { class: 'clock__controls' }, this.playPauseButton, ...this.speedButtons),
      ),
-      el('p', { class: 'hint', text: 'Школа пока пуста — здесь появится сама игра.' }),
+      this.emptyHint,
    );
+
+    this.localize();
  }

  get element(): HTMLElement {
    return this.root;
  }

+  localize(): void {
+    this.backButton.textContent = t('backToMenu');
+    this.emptyHint.textContent = t('emptySchoolHint');
+
+    if (this.lastGameTime !== null) {
+      this.applyClock(this.lastGameTime, this.running, this.lastSpeedIndex);
+    } else {
+      this.playPauseButton.title = t('resume');
+    }
+  }
+
  /** Called when the screen opens, before the first clock frame arrives. */
  show(school: School): void {
    this.schoolName.textContent = school.name;
@@ -73,13 +87,15 @@ export class GameScreen {

  private applyClock(gameTime: Date, running: boolean, speedIndex: number): void {
    this.running = running;
+    this.lastGameTime = gameTime;
+    this.lastSpeedIndex = speedIndex;

    this.time.textContent = formatGameTimeOfDay(gameTime);
    this.date.textContent = formatGameDate(gameTime);
    this.weekday.textContent = formatGameWeekday(gameTime);

    this.playPauseButton.textContent = running ? '⏸' : '▶';
-    this.playPauseButton.title = running ? 'Пауза' : 'Продолжить';
+    this.playPauseButton.title = running ? t('pause') : t('resume');

    this.speedButtons.forEach((button, index) => {
      button.classList.toggle('button--active', index === speedIndex);
@@ -0,0 +1,39 @@
+import { el } from './dom.ts';
+import { LOCALES, getLocale, setLocale, onLocaleChange, type Locale } from '../i18n/locale.ts';
+import { t } from '../i18n/strings.ts';
+
+const LABELS: Record<Locale, string> = { ru: 'RU', en: 'EN' };
+
+/** Compact RU/EN toggle for the status footer — always on screen, both menus. */
+export function localeSwitch(): HTMLElement {
+  const buttons = new Map<Locale, HTMLButtonElement>();
+
+  const group = el('div', { class: 'locale-switch' });
+  group.setAttribute('role', 'group');
+
+  for (const locale of LOCALES) {
+    const button = el('button', {
+      class: 'locale-switch__button',
+      type: 'button',
+      text: LABELS[locale],
+      onClick: () => setLocale(locale),
+    });
+    button.setAttribute('lang', locale);
+    buttons.set(locale, button);
+    group.append(button);
+  }
+
+  const sync = (): void => {
+    group.setAttribute('aria-label', t('language'));
+    const active = getLocale();
+
+    for (const [locale, button] of buttons) {
+      button.setAttribute('aria-pressed', locale === active ? 'true' : 'false');
+    }
+  };
+
+  onLocaleChange(sync);
+  sync();
+
+  return group;
+}
@@ -6,6 +6,8 @@ import {
  type School,
  type SchoolsResponse,
 } from '../net/api.ts';
+import { getLocale } from '../i18n/locale.ts';
+import { schoolWord, t } from '../i18n/strings.ts';
 import { el } from './dom.ts';
 import { confirmDialog } from './confirmDialog.ts';
 import { createSchoolDialog } from './createSchoolDialog.ts';
@@ -26,12 +28,12 @@ const REFRESH_INTERVAL_MS = 1000;

 export class MainMenu {
  private readonly root = el('section', { class: 'screen menu' });
+  private readonly title = el('h1', { class: 'screen__title' });
  private readonly grid = el('div', { class: 'card-grid' });
-  private readonly emptyHint = el('p', { class: 'hint', text: 'Пока ни одной школы. Создайте первую.' });
+  private readonly emptyHint = el('p', { class: 'hint' });
  private readonly createButton = el('button', {
    class: 'button button--primary',
    type: 'button',
-    text: 'Создать школу',
  });

  private readonly limitHint = el('p', { class: 'hint' });
@@ -41,6 +43,7 @@ export class MainMenu {
  private state: SchoolsResponse | null = null;
  private refreshTimer: ReturnType<typeof setInterval> | null = null;
  private busy = false;
+  private error: { key: 'loadSchoolsFailed' } | { key: 'deleteFailed'; name: string } | null = null;

  constructor(private readonly options: MainMenuOptions) {
    this.createButton.addEventListener('click', () => void this.openCreateDialog());
@@ -50,7 +53,7 @@ export class MainMenu {
      el(
        'header',
        { class: 'screen__header' },
-        el('h1', { class: 'screen__title', text: 'Школы' }),
+        this.title,
        el('div', { class: 'screen__actions' }, this.createButton),
      ),
      this.limitHint,
@@ -58,12 +61,28 @@ export class MainMenu {
      this.emptyHint,
      this.grid,
    );
+
+    this.localize();
  }

  get element(): HTMLElement {
    return this.root;
  }

+  /** Re-applies strings after a language switch. Cards stay in place so focus is not dropped. */
+  localize(): void {
+    this.title.textContent = t('schoolsTitle');
+    this.createButton.textContent = t('createSchool');
+    this.emptyHint.textContent = t('emptySchools');
+
+    for (const card of this.cards.values()) {
+      card.localize();
+    }
+
+    this.paintError();
+    this.render();
+  }
+
  /** Shows the menu: loads the list once, then keeps it fresh. */
  start(): void {
    void this.refresh();
@@ -86,16 +105,30 @@ export class MainMenu {
  async refresh(): Promise<void> {
    try {
      this.state = await fetchSchools();
-      this.status.hidden = true;
+      this.error = null;
    } catch {
-      this.status.textContent = 'Не удалось загрузить список школ. Проверьте соединение с сервером.';
-      this.status.hidden = false;
+      this.error = { key: 'loadSchoolsFailed' };
+      this.paintError();
      return;
    }

+    this.paintError();
    this.render();
  }

+  private paintError(): void {
+    if (this.error === null) {
+      this.status.hidden = true;
+      return;
+    }
+
+    this.status.textContent =
+      this.error.key === 'loadSchoolsFailed'
+        ? t('loadSchoolsFailed')
+        : t('deleteFailed', { name: this.error.name });
+    this.status.hidden = false;
+  }
+
  private render(): void {
    const state = this.state;
    if (state === null) {
@@ -104,11 +137,11 @@ export class MainMenu {

    const atLimit = state.schools.length >= state.maxSchools;
    this.createButton.toggleAttribute('disabled', atLimit || this.busy);
-    this.createButton.title = atLimit ? 'Удалите одну из школ, чтобы создать новую' : '';
+    this.createButton.title = atLimit ? t('createDisabledTitle') : '';

    this.limitHint.textContent = atLimit
-      ? `Достигнут лимит: ${state.maxSchools} ${plural(state.maxSchools)}. Удалите одну, чтобы создать новую.`
-      : `Школ: ${state.schools.length} из ${state.maxSchools}.`;
+      ? t('schoolLimitReached', { max: state.maxSchools, schoolWord: schoolWord(state.maxSchools) })
+      : t('schoolCount', { current: state.schools.length, max: state.maxSchools });

    this.emptyHint.hidden = state.schools.length > 0;

@@ -141,9 +174,9 @@ export class MainMenu {

  private async confirmDelete(school: School): Promise<void> {
    const confirmed = await confirmDialog({
-      title: 'Удалить школу?',
-      message: `«${school.name}» будет удалена без возможности восстановления.`,
-      confirmLabel: 'Удалить',
+      title: t('deleteSchoolTitle'),
+      message: t('deleteSchoolMessage', { name: school.name }),
+      confirmLabel: t('deleteSchool'),
      danger: true,
    });

@@ -154,8 +187,7 @@ export class MainMenu {
    try {
      await deleteSchool(school.id);
    } catch {
-      this.status.textContent = `Не удалось удалить «${school.name}».`;
-      this.status.hidden = false;
+      this.error = { key: 'deleteFailed', name: school.name };
    }

    await this.refresh();
@@ -171,7 +203,7 @@ export class MainMenu {
    try {
      await createSchoolDialog({
        defaultStartDate: new Date(state.defaultStartDate),
-        suggestName: fetchRandomName,
+        suggestName: () => fetchRandomName(getLocale()),
        create: createSchool,
      });
    } finally {
@@ -181,12 +213,3 @@ export class MainMenu {
    await this.refresh();
  }
 }
-
-function plural(count: number): string {
-  const remainderTen = count % 10;
-  const remainderHundred = count % 100;
-
-  if (remainderTen === 1 && remainderHundred !== 11) return 'школа';
-  if (remainderTen >= 2 && remainderTen <= 4 && (remainderHundred < 12 || remainderHundred > 14)) return 'школы';
-  return 'школ';
-}
@@ -1,5 +1,6 @@
 import type { School } from '../net/api.ts';
 import { formatGameDateTime } from '../format/gameTime.ts';
+import { t } from '../i18n/strings.ts';
 import { el } from './dom.ts';

 interface SchoolCardOptions {
@@ -16,7 +17,11 @@ export class SchoolCard {

  private readonly title = el('h2', { class: 'card__title' });
  private readonly time = el('p', { class: 'card__time' });
-  private readonly pausedBadge = el('span', { class: 'card__badge', text: '⏸ на паузе' });
+  private readonly pausedBadge = el('span', { class: 'card__badge' });
+  private readonly deleteButton = el('button', {
+    class: 'button button--danger button--small',
+    type: 'button',
+  });

  private school: School;

@@ -25,23 +30,16 @@ export class SchoolCard {

    this.element.dataset['schoolId'] = String(school.id);
    this.element.tabIndex = 0;
+    this.deleteButton.addEventListener('click', (event) => {
+      // The whole card is clickable, so the delete button must not open the school too.
+      event.stopPropagation();
+      options.onDelete(this.school);
+    });
+
    this.element.append(
      this.title,
      el('div', { class: 'card__meta' }, this.time, this.pausedBadge),
-      el(
-        'div',
-        { class: 'card__actions' },
-        el('button', {
-          class: 'button button--danger button--small',
-          type: 'button',
-          text: 'Удалить',
-          onClick: (event) => {
-            // The whole card is clickable, so the delete button must not open the school too.
-            event.stopPropagation();
-            options.onDelete(this.school);
-          },
-        }),
-      ),
+      el('div', { class: 'card__actions' }, this.deleteButton),
    );

    this.element.addEventListener('click', () => options.onOpen(this.school));
@@ -52,9 +50,16 @@ export class SchoolCard {
      }
    });

+    this.localize();
    this.update(school);
  }

+  localize(): void {
+    this.deleteButton.textContent = t('deleteSchool');
+    this.pausedBadge.textContent = t('paused');
+    this.update(this.school);
+  }
+
  update(school: School): void {
    this.school = school;

@@ -29,9 +29,9 @@ internal static class SchoolEndpoints
        })
        .WithName("GetSchools");

-        schools.MapGet("/random-name", async (GameCommandQueue commands, CancellationToken cancellationToken) =>
+        schools.MapGet("/random-name", async (string? lang, GameCommandQueue commands, CancellationToken cancellationToken) =>
        {
-            var command = new GameCommand.SuggestName(NewCompletion<string>());
+            var command = new GameCommand.SuggestName(ParseNameLanguage(lang), NewCompletion<string>());
            commands.Enqueue(command);

            var name = await command.Result.Task.WaitAsync(CommandTimeout, cancellationToken);
@@ -85,6 +85,11 @@ internal static class SchoolEndpoints
    private static TaskCompletionSource<T> NewCompletion<T>() =>
        new(TaskCreationOptions.RunContinuationsAsynchronously);

+    private static SchoolNameLanguage ParseNameLanguage(string? lang) =>
+        string.Equals(lang, "en", StringComparison.OrdinalIgnoreCase)
+            ? SchoolNameLanguage.English
+            : SchoolNameLanguage.Russian;
+
    private static IResult Problem(int statusCode, string code, string detail) =>
        Results.Problem(detail: detail, statusCode: statusCode, title: code, extensions: new Dictionary<string, object?>
        {
@@ -1,3 +1,5 @@
+using HSchool.Simulation;
+
 namespace HSchool.Server.Game;

 /// <summary>
@@ -13,7 +15,7 @@ internal abstract record GameCommand

    internal sealed record DeleteSchool(int SchoolId, TaskCompletionSource<bool> Result) : GameCommand;

-    internal sealed record SuggestName(TaskCompletionSource<string> Result) : GameCommand;
+    internal sealed record SuggestName(SchoolNameLanguage Language, TaskCompletionSource<string> Result) : GameCommand;

    /// <summary>A connection starts watching a school; its calendar starts running.</summary>
    internal sealed record OpenSchool(uint PlayerId, int SchoolId) : GameCommand;
@@ -111,7 +111,7 @@ internal sealed class GameLoopService(
                    break;

                case GameCommand.SuggestName suggest:
-                    Complete(suggest.Result, _schools.SuggestName);
+                    Complete(suggest.Result, () => _schools.SuggestName(suggest.Language));
                    break;

                case GameCommand.OpenSchool open:
@@ -1,5 +1,12 @@
 namespace HSchool.Simulation;

+/// <summary>Which word list the random-name button draws from.</summary>
+public enum SchoolNameLanguage
+{
+    Russian = 0,
+    English = 1,
+}
+
 /// <summary>
 /// Suggestions for the "random name" button. Lives here rather than in the client because the
 /// server is the one that knows which names are already taken.
@@ -8,13 +15,35 @@ public sealed class SchoolNameGenerator(Random? random = null)
 {
    private const int AttemptsBeforeNumbering = 24;

-    private static readonly string[] Kinds = ["Школа", "Гимназия", "Лицей", "Школа-интернат"];
+    private readonly record struct Catalog(
+        string[] Kinds,
+        string[] Epithets,
+        string NumberSign,
+        bool NumberSpace,
+        bool EpithetFirst,
+        string FallbackKind);

-    private static readonly string[] Epithets =
-    [
-        "Северная", "Приморская", "Заречная", "Нагорная", "Слободская", "Озёрная",
-        "Кленовая", "Рябиновая", "Солнечная", "Луговая", "Тихая", "Ясная",
-    ];
+    private static readonly Catalog Russian = new(
+        ["Школа", "Гимназия", "Лицей", "Школа-интернат"],
+        [
+            "Северная", "Приморская", "Заречная", "Нагорная", "Слободская", "Озёрная",
+            "Кленовая", "Рябиновая", "Солнечная", "Луговая", "Тихая", "Ясная",
+        ],
+        "№",
+        false,
+        false,
+        "Школа");
+
+    private static readonly Catalog English = new(
+        ["School", "Academy", "Grammar School", "High School"],
+        [
+            "Northern", "Seaside", "Riverside", "Hillside", "Maple", "Rowan",
+            "Sunny", "Meadow", "Quiet", "Clear", "Oak", "Pine",
+        ],
+        "No.",
+        true,
+        true,
+        "School");

    private readonly Random _random = random ?? Random.Shared;

@@ -22,13 +51,14 @@ public sealed class SchoolNameGenerator(Random? random = null)
    /// A name that is not in <paramref name="taken"/>. Falls back to a numbered name so the
    /// button always produces something, even when the pool is exhausted.
    /// </summary>
-    public string Next(IEnumerable<string> taken)
+    public string Next(IEnumerable<string> taken, SchoolNameLanguage language = SchoolNameLanguage.Russian)
    {
+        var catalog = language == SchoolNameLanguage.English ? English : Russian;
        var used = new HashSet<string>(taken, StringComparer.OrdinalIgnoreCase);

        for (var attempt = 0; attempt < AttemptsBeforeNumbering; attempt++)
        {
-            var candidate = Compose();
+            var candidate = Compose(catalog);
            if (used.Add(candidate))
            {
                return candidate;
@@ -37,7 +67,7 @@ public sealed class SchoolNameGenerator(Random? random = null)

        for (var number = 1; ; number++)
        {
-            var candidate = $"Школа №{number}";
+            var candidate = Numbered(catalog, catalog.FallbackKind, number);
            if (!used.Contains(candidate))
            {
                return candidate;
@@ -45,13 +75,24 @@ public sealed class SchoolNameGenerator(Random? random = null)
        }
    }

-    private string Compose()
+    private string Compose(Catalog catalog)
    {
-        var kind = Kinds[_random.Next(Kinds.Length)];
+        var kind = catalog.Kinds[_random.Next(catalog.Kinds.Length)];

        // Half the names are numbered, half are named — both read like a real school.
-        return _random.Next(2) == 0
-            ? $"{kind} №{_random.Next(1, 100)}"
-            : $"{kind} «{Epithets[_random.Next(Epithets.Length)]}»";
+        if (_random.Next(2) == 0)
+        {
+            return Numbered(catalog, kind, _random.Next(1, 100));
+        }
+
+        var epithet = catalog.Epithets[_random.Next(catalog.Epithets.Length)];
+        return catalog.EpithetFirst
+            ? $"{epithet} {kind}"
+            : $"{kind} «{epithet}»";
    }
+
+    private static string Numbered(Catalog catalog, string kind, int number) =>
+        catalog.NumberSpace
+            ? $"{kind} {catalog.NumberSign} {number}"
+            : $"{kind} {catalog.NumberSign}{number}";
 }
@@ -100,7 +100,8 @@ public sealed class SchoolRegistry : IDisposable
    }

    /// <summary>A name the player has not used yet, for the "random" button in the creation form.</summary>
-    public string SuggestName() => NameGenerator.Next(_schools.Select(school => school.Name));
+    public string SuggestName(SchoolNameLanguage language = SchoolNameLanguage.Russian) =>
+        NameGenerator.Next(_schools.Select(school => school.Name), language);

    /// <summary>Trims, strips control characters and enforces the length limit.</summary>
    public static bool TryNormalizeName(string? name, out string normalized)
@@ -159,10 +159,25 @@ public class SchoolRegistryTests
    {
        var generator = new SchoolNameGenerator(new Random(1234));

-        for (var i = 0; i < 200; i++)
+        foreach (var language in new[] { SchoolNameLanguage.Russian, SchoolNameLanguage.English })
        {
-            var name = generator.Next([]);
-            Assert.InRange(name.Length, 1, School.MaxNameLength);
+            for (var i = 0; i < 200; i++)
+            {
+                var name = generator.Next([], language);
+                Assert.InRange(name.Length, 1, School.MaxNameLength);
+            }
+        }
+    }
+
+    [Fact]
+    public void SuggestedEnglishNames_AreAscii()
+    {
+        var generator = new SchoolNameGenerator(new Random(1234));
+
+        for (var i = 0; i < 50; i++)
+        {
+            var name = generator.Next([], SchoolNameLanguage.English);
+            Assert.Matches("^[A-Za-z0-9 .]+$", name);
        }
    }