feat: embeddable CompanyGame with loader, poster, no-WebGL fallback and SEO

- CompanyGame bundles the store, a branded loader with start-up progress, an optional
  light poster (Enter the game) and a company-info fallback when WebGL is missing.
- startMode prop and ?mode= start straight in a mode; ?poster shows the poster first.
- Pixel ratio capped at 1.5 on touch devices and 1.75 on desktop (constants/graphics.js).
- Build writes the title, description, Organization JSON-LD and a hidden Persian
  summary into index.html from the company config.
- README explains iframe and component embedding.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -237,6 +237,32 @@ node scripts/fetch-imagery.mjs
 
 **مجوز:** استفادهٔ تجاری و میزبانی نسخه‌ای از تصاویر Esri نیاز به مجوز مناسب از Esri دارد. شرایط را با Esri بررسی کنید. نام منبع در پایین صفحهٔ بازی نمایش داده می‌شود.
 
+## جاسازی در سایت شرکت
+
+بازی کل صفحه را می‌گیرد، پس بهترین راه جاسازی یک صفحهٔ جدا یا یک `iframe` است:
+
+```html
+<iframe src="https://robotmarkets.ir/game/?poster&mode=about" title="بازی روبات مارکت"
+  style="width:100%;height:100dvh;border:0" allow="fullscreen; geolocation; camera"></iframe>
+```
+
+- `?poster`: اول یک پوستر سبک با دکمهٔ «ورود به بازی» نشان داده می‌شود و بازی سه‌بعدی فقط با کلیک بارگذاری می‌شود. این برای صفحهٔ اصلی سایت مناسب است.
+- `?mode=real|offline|about|products`: بازی بدون صفحهٔ شروع، مستقیم در همان حالت شروع می‌شود. حالت دنیای واقعی همچنان اول پیام ایمنی را نشان می‌دهد.
+
+در یک پروژهٔ React همین کار با کامپوننت انجام می‌شود:
+
+```jsx
+import { CompanyGame } from '@/pages/game/CompanyGame.jsx';
+
+<CompanyGame startMode="products" showPoster />;
+```
+
+- `CompanyGame` استور Redux، صفحهٔ بارگذاری با نوار پیشرفت، پوستر و حالت بدون WebGL را خودش دارد.
+- اگر مرورگر WebGL نداشته باشد، به‌جای بازی پیام کوتاه و اطلاعات شرکت (معرفی، تماس و آدرس) نشان داده می‌شود.
+- رنگ‌ها و اطلاعات برند از `src/config/company.js` می‌آیند، نه از props، چون مدل‌های سه‌بعدی هم از همان رنگ‌ها ساخته می‌شوند.
+- عنوان صفحه، توضیح، دادهٔ ساخت‌یافتهٔ Organization و یک خلاصهٔ فارسی پنهان (برای موتورهای جست‌وجو) هنگام ساخت از همان فایل در `index.html` نوشته می‌شوند (`src/utils/seoSummary.js`).
+- برای کارایی: صفحهٔ بازی و Three.js یک بستهٔ جدا هستند، تراکم پیکسل روی گوشی ۱٫۵ و روی دسکتاپ ۱٫۷۵ محدود است، و هنگام بستن بازی همهٔ هندسه‌ها، متریال‌ها، بافت‌ها، تایمرها و حسگرها آزاد می‌شوند.
+
 ## ساختار
 
 - `src/config/company.js`: همهٔ اطلاعات شرکت در یک جا: نام، شعار، رنگ‌های برند (رنگ اصلی `#00a693` و طیف آن)، آدرس، تلفن، ایمیل، شبکه‌های اجتماعی، درباره‌ما و فهرست محصولات. مقدارهای `TODO(company)` جایگزین‌شدنی‌اند.

index.html

@@ -4,11 +4,8 @@
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width,initial-scale=1,viewport-fit=cover" />
     <meta name="theme-color" content="#0b1614" />
-    <title>عملیات مشهد | روبات مارکت</title>
-    <meta
-      name="description"
-      content="از کارخانهٔ روبات مارکت تا بوستان ملت: دستگاه‌های وندینگ را در مشهد پیدا کن و امتیاز بگیر."
-    />
+    <!-- Title, description and structured data come from the company config (vite.config.js). -->
+    <!--seo-head-->
     <meta name="mobile-web-app-capable" content="yes" />
     <meta name="apple-mobile-web-app-capable" content="yes" />
     <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent" />
@@ -18,6 +15,7 @@
     <link rel="apple-touch-icon" href="./icons/apple-touch-icon.png" />
   </head>
   <body>
+    <!--seo-summary-->
     <div id="root"></div>
     <script type="module" src="/src/main.jsx"></script>
   </body>

src/constants/graphics.js

@@ -0,0 +1,5 @@
+// Device pixel ratio caps. Rendering at the full ratio of a 3× phone screen costs nine times the
+// pixels for little visible gain, so it is capped; the low setting renders at 1× for weak devices.
+export const PIXEL_RATIO_LOW = 1;
+export const PIXEL_RATIO_MOBILE = 1.5;
+export const PIXEL_RATIO_DESKTOP = 1.75;

src/game/createGame.js

@@ -1,19 +1,24 @@
 import { bindRuntime, RUNTIME_INITIALIZERS } from './runtime/runtimeBindings.js';
 /** Starts isolated systems in dependency order and returns their shared lifecycle cleanup.
- * @param {{root:HTMLElement,ui:object,signal:AbortSignal}} options - React mount context.
+ * Reports start-up progress (0–1) on the `loading` interface node as each system is ready.
+ * @param {{root:HTMLElement,ui:object,signal:AbortSignal,startMode?:string}} options - React
+ * mount context, and a start mode that skips the start screen.
  * @returns {Promise<function>} Disposes input, timers, sensors and graphics.
  */
-export async function createGame({ root, ui, signal }) {
+export async function createGame({ root, ui, signal, startMode }) {
   const context = {
     root,
     ui,
     signal,
+    startMode: null,
+    requestedMode: startMode ?? null,
   };
   bindRuntime(context);
   try {
-    for (const initialize of RUNTIME_INITIALIZERS) {
+    for (const [index, initialize] of RUNTIME_INITIALIZERS.entries()) {
       if (signal.aborted) break;
       await initialize(context);
+      ui.patch('loading', { progress: (index + 1) / RUNTIME_INITIALIZERS.length });
     }
   } catch (error) {
     context.renderer?.dispose();

src/game/device/webgl.js

@@ -0,0 +1,15 @@
+/**
+ * Whether this browser can draw the 3D world. Creates a throwaway canvas and releases its context
+ * straight away, so the check costs nothing once the answer is known.
+ * @returns {boolean} True when a WebGL context is available.
+ */
+export function supportsWebgl() {
+  try {
+    const canvas = document.createElement('canvas');
+    const gl = canvas.getContext('webgl2') ?? canvas.getContext('webgl');
+    gl?.getExtension('WEBGL_lose_context')?.loseContext();
+    return Boolean(gl);
+  } catch {
+    return false;
+  }
+}

src/game/runtime/runtimeSetup.js

@@ -27,6 +27,11 @@ import { formatDistance, toLocal } from '../../utils/geo.js';
 import { strings } from '../../i18n/fa.js';
 import { COMPANY } from '../../config/company.js';
 import { SHOWROOM_POINT_ID } from '../../constants/factoryPoints.js';
+import {
+  PIXEL_RATIO_DESKTOP,
+  PIXEL_RATIO_LOW,
+  PIXEL_RATIO_MOBILE,
+} from '../../constants/graphics.js';
 import { createObjectiveArrow } from '../models/objectiveArrow.js';
 
 // Brand colours for materials and canvas drawings.
@@ -95,7 +100,10 @@ export async function initializeRenderer(context) {
       }
     })() ??
     (matchMedia('(pointer: coarse)').matches ? 'low' : 'high');
-  context.renderer.setPixelRatio(context.quality === 'low' ? 1 : Math.min(devicePixelRatio, 1.75));
+  const cap = matchMedia('(pointer: coarse)').matches ? PIXEL_RATIO_MOBILE : PIXEL_RATIO_DESKTOP;
+  context.renderer.setPixelRatio(
+    context.quality === 'low' ? PIXEL_RATIO_LOW : Math.min(devicePixelRatio, cap),
+  );
 }
 /**
  * Initializes scene in dependency order.
@@ -1247,6 +1255,10 @@ export async function startGameLoop(context) {
     hidden: true,
   });
   context.frameId = requestAnimationFrame(context.frame);
+  // An embedding page may ask for a mode directly (CompanyGame's startMode, or ?mode=). Real-world
+  // play still shows its safety notice first, and asks for location from the tap on it.
+  if (context.requestedMode === 'real') context.askRealMode(true);
+  else if (context.requestedMode) context.startGame(context.requestedMode);
 }
 /**
  * Initializes dispose in dependency order.

src/hooks/useGameEngine.js

@@ -3,9 +3,10 @@ import { useEffect, useRef, useState } from 'react';
 /** Mounts one game runtime and releases its GPU, input, sensor and timer resources.
  * @param {object} root - React ref containing all render surfaces.
  * @param {object} bridge - Interface publisher owned by this page.
+ * @param {string} [startMode] - Mode to start in directly, skipping the start screen.
  * @returns {{error:string|null}} Startup failure for the accessible loading surface.
  */
-export function useGameEngine(root, bridge) {
+export function useGameEngine(root, bridge, startMode) {
   const [error, setError] = useState(null);
   const disposeRef = useRef(null);
   useEffect(() => {
@@ -23,6 +24,7 @@ export function useGameEngine(root, bridge) {
           root: root.current,
           ui: bridge,
           signal: controller.signal,
+          startMode,
         });
         if (controller.signal.aborted) dispose();
         else disposeRef.current = dispose;
@@ -40,7 +42,7 @@ export function useGameEngine(root, bridge) {
       disposeRef.current?.();
       disposeRef.current = null;
     };
-  }, [root, bridge]);
+  }, [root, bridge, startMode]);
   return {
     error,
   };

src/i18n/fa.js

@@ -31,9 +31,24 @@ export const strings = {
     hetomanName: 'هتومان',
     speed: 'km/h',
   },
+  // Search-engine text written into index.html at build time (utils/seoSummary.js).
+  seo: {
+    title: `${COMPANY.name} | بازی سه‌بعدی دستگاه‌های وندینگ`,
+    description: `${COMPANY.tagline}. کارخانه، محصولات و دستگاه‌های نصب‌شدهٔ ${COMPANY.shortName} را در یک بازی سه‌بعدی در مشهد ببینید.`,
+    summaryLabel: 'خلاصهٔ معرفی شرکت',
+    productsHeading: 'محصولات',
+  },
+  // Poster shown before the 3D game loads, and instead of it when the browser cannot draw 3D.
+  poster: {
+    enter: 'ورود به بازی',
+    noWebgl:
+      'مرورگر یا دستگاه شما بازی سه‌بعدی را اجرا نمی‌کند. اطلاعات شرکت را این‌جا ببینید یا با مرورگر دیگری امتحان کنید.',
+    heroAlt: `نمای کارخانهٔ ${COMPANY.shortName}`,
+  },
   app: {
-    preparing: 'در حال آماده‌سازی بازی…',
     buildingCity: 'در حال ساختن شهر مشهد…',
+    /** @type {(percent: string) => string} */
+    loadingPercent: (percent) => `${percent}٪`,
     /** @type {(error: string) => string} */
     failed: (error) => `بازی اجرا نشد: ${error}`,
     retry: 'تلاش دوباره',

src/main.jsx

@@ -1,13 +1,8 @@
 import { createRoot } from 'react-dom/client';
-import { Provider } from 'react-redux';
 import { AppRoutes } from '@/routes/AppRoutes.jsx';
-import { store } from '@/store/index.js';
 import '@fontsource/vazirmatn/400.css';
 import '@fontsource/vazirmatn/600.css';
 import '@fontsource/vazirmatn/800.css';
 import '@/styles/game.css';
-createRoot(document.getElementById('root')).render(
-  <Provider store={store}>
-    <AppRoutes />
-  </Provider>,
-);
+// The store is provided inside CompanyGame, so the game can also be mounted on its own.
+createRoot(document.getElementById('root')).render(<AppRoutes />);

src/pages/game/CompanyGame.jsx

@@ -0,0 +1,39 @@
+import { Suspense, lazy, useState } from 'react';
+import { Provider } from 'react-redux';
+import { store } from '@/store/index.js';
+import { supportsWebgl } from '@/game/device/webgl.js';
+import { GamePoster } from './GamePoster.jsx';
+import { GameLoader } from './GameLoader.jsx';
+
+// The game page (and Three.js with it) is a separate chunk, fetched only when the game starts.
+const GamePage = lazy(() =>
+  import('./GamePage.jsx').then((module) => ({ default: module.GamePage })),
+);
+
+/**
+ * @typedef {object} CompanyGameProps
+ * @property {'real' | 'offline' | 'about' | 'products'} [startMode] - Start straight in this mode
+ * instead of showing the start screen.
+ * @property {boolean} [showPoster] - Show a light poster with an "Enter the game" button first,
+ * so the 3D game only loads when the visitor asks (good for landing pages). Default false.
+ */
+/**
+ * The whole company game as one self-contained component: store, loader, poster, no-WebGL
+ * fallback and the game itself. Mount it on a full-page route (or in an iframe); the game uses
+ * the whole viewport.
+ * @param {CompanyGameProps} props - Embedding options.
+ * @returns {import('react').ReactElement} Game, poster or fallback.
+ */
+export function CompanyGame({ startMode, showPoster = false }) {
+  const [canRender] = useState(supportsWebgl);
+  const [entered, setEntered] = useState(!showPoster);
+  if (!canRender || !entered)
+    return <GamePoster canRender={canRender} onEnter={() => setEntered(true)} />;
+  return (
+    <Provider store={store}>
+      <Suspense fallback={<GameLoader nodes={{}} />}>
+        <GamePage startMode={startMode} />
+      </Suspense>
+    </Provider>
+  );
+}

src/pages/game/GameLoader.jsx

@@ -0,0 +1,41 @@
+import { COMPANY } from '@/config/company.js';
+import { ASSETS } from '@/config/assets.js';
+import { strings } from '@/i18n/fa.js';
+
+/** @typedef {{nodes: object}} GameLoaderProps */
+/**
+ * Branded loading screen with a progress bar, shown while the 3D world is being built.
+ * @param {GameLoaderProps} props - Interface snapshots; `loading` carries progress (0–1).
+ * @returns {import('react').ReactElement} Loading screen.
+ */
+export function GameLoader({ nodes }) {
+  const loading = nodes.loading ?? {};
+  const percent = Math.round((loading.progress ?? 0) * 100);
+  return (
+    <section id="loading" hidden={loading.hidden} aria-busy={!loading.hidden}>
+      <div className="flex w-64 flex-col items-center gap-4 text-center">
+        <img
+          src={ASSETS.brand.logo}
+          alt={strings.landing.logoAlt}
+          className="h-16 w-16 rounded-2xl"
+        />
+        <p className="text-lg font-bold text-hud">{COMPANY.shortName}</p>
+        <div
+          role="progressbar"
+          aria-label={strings.app.buildingCity}
+          aria-valuemin={0}
+          aria-valuemax={100}
+          aria-valuenow={percent}
+          className="h-2 w-full overflow-hidden rounded-full bg-white/10"
+        >
+          {/* Width is the live progress, so it is the one inline style here. */}
+          <div className="h-full rounded-full bg-primary" style={{ width: `${percent}%` }} />
+        </div>
+        <p className="text-sm">
+          {loading.text ?? strings.app.buildingCity}{' '}
+          <span dir="ltr">{strings.app.loadingPercent(percent.toLocaleString('fa-IR'))}</span>
+        </p>
+      </div>
+    </section>
+  );
+}

src/pages/game/GamePage.jsx

@@ -6,18 +6,23 @@ import { createInterfaceBridge } from '@/game/interfaceBridge.js';
 import { useGameEngine } from '@/hooks/useGameEngine.js';
 import { setupPwa } from '@/game/device/pwa.js';
 import { GameSurfaces } from './GameSurfaces.jsx';
+import { GameLoader } from './GameLoader.jsx';
 import { StartScreen } from './startScreen/StartScreen.jsx';
 import { GameHud } from './GameHud.jsx';
 import { GameDialogs } from './GameDialogs.jsx';
 import { strings } from '@/i18n/fa.js';
 
-/** Composes React views around the isolated Three.js runtime. */
-export function GamePage() {
+/**
+ * Composes React views around the isolated Three.js runtime.
+ * @param {{startMode?: string}} props - Mode to start in directly, skipping the start screen.
+ * @returns {import('react').ReactElement} Game page.
+ */
+export function GamePage({ startMode }) {
   const root = useRef(null),
     store = useStore();
   const bridge = useMemo(() => createInterfaceBridge(store), [store]);
   const nodes = useAppSelector(selectNodes);
-  const { error } = useGameEngine(root, bridge);
+  const { error } = useGameEngine(root, bridge, startMode);
   useEffect(() => {
     bridge.activate();
     const dispose = setupPwa(bridge);
@@ -41,6 +46,7 @@ export function GamePage() {
   return (
     <main ref={root}>
       <GameSurfaces {...props} />
+      <GameLoader {...props} />
       <StartScreen {...props} />
       <GameHud {...props} />
       <GameDialogs {...props} />

src/pages/game/GamePoster.jsx

@@ -0,0 +1,73 @@
+import { COMPANY } from '@/config/company.js';
+import { ASSETS } from '@/config/assets.js';
+import { strings } from '@/i18n/fa.js';
+import { SECTION_BODIES } from './startScreen/InfoSectionContent.jsx';
+
+// Company sections the poster shows when the 3D game cannot run.
+const FALLBACK_SECTIONS = ['about', 'contact', 'address'];
+
+/** @typedef {{canRender: boolean, onEnter: function}} GamePosterProps */
+/**
+ * Light poster in place of the 3D game: a hero image and an "Enter the game" button, so an
+ * embedding page loads nothing heavy until the visitor asks. When the browser cannot draw 3D it
+ * explains that and shows the company information instead.
+ * @param {GamePosterProps} props - Whether WebGL works, and the callback that starts the game.
+ * @returns {import('react').ReactElement} Poster.
+ */
+export function GamePoster({ canRender, onEnter }) {
+  return (
+    <main className="min-h-dvh bg-surface text-hud">
+      <div className="relative">
+        <img
+          src={ASSETS.brand.hero}
+          alt={strings.poster.heroAlt}
+          className="h-[45dvh] w-full object-cover opacity-60"
+        />
+        <div className="absolute inset-x-0 bottom-0 bg-gradient-to-t from-surface to-transparent p-6 pt-20">
+          <div className="mx-auto max-w-2xl">
+            <p className="text-2xl font-black md:text-4xl">{COMPANY.name}</p>
+            <p className="mt-2 text-primary">{COMPANY.tagline}</p>
+          </div>
+        </div>
+      </div>
+      <div className="mx-auto max-w-2xl p-6">
+        <p className="opacity-80">{strings.landing.intro}</p>
+        {canRender ? (
+          <button
+            type="button"
+            className="start-option start-option-primary mt-6"
+            onClick={onEnter}
+          >
+            {strings.poster.enter}
+          </button>
+        ) : (
+          <FallbackInfo />
+        )}
+      </div>
+    </main>
+  );
+}
+
+/**
+ * Company information for browsers without 3D support.
+ * @returns {import('react').ReactElement} Notice and sections.
+ */
+function FallbackInfo() {
+  return (
+    <>
+      <p role="alert" className="mt-6 rounded-xl border border-primary/40 p-4">
+        {strings.poster.noWebgl}
+      </p>
+      {FALLBACK_SECTIONS.map((key) => {
+        const Body = SECTION_BODIES[key];
+        const title = key === 'about' ? strings.landing.history : strings.landing.sections[key];
+        return (
+          <section key={key} className="mt-8">
+            <h2 className="mb-3 text-lg font-bold">{title}</h2>
+            <Body />
+          </section>
+        );
+      })}
+    </>
+  );
+}

src/pages/game/GamePoster.test.jsx

@@ -0,0 +1,33 @@
+import { describe, it, expect, vi, afterEach } from 'vitest';
+import { render, screen, fireEvent, cleanup } from '@testing-library/react';
+import { COMPANY } from '@/config/company.js';
+import { strings } from '@/i18n/fa.js';
+import { GamePoster } from './GamePoster.jsx';
+import { GameLoader } from './GameLoader.jsx';
+
+afterEach(cleanup);
+
+describe('GamePoster', () => {
+  it('starts the game from the enter button when 3D works', () => {
+    const onEnter = vi.fn();
+    render(<GamePoster canRender onEnter={onEnter} />);
+    expect(screen.getByText(COMPANY.name)).toBeInTheDocument();
+    fireEvent.click(screen.getByRole('button', { name: strings.poster.enter }));
+    expect(onEnter).toHaveBeenCalled();
+  });
+
+  it('explains missing 3D support and shows the company information instead', () => {
+    render(<GamePoster canRender={false} onEnter={vi.fn()} />);
+    expect(screen.getByRole('alert')).toHaveTextContent(strings.poster.noWebgl);
+    expect(screen.queryByRole('button', { name: strings.poster.enter })).not.toBeInTheDocument();
+    expect(screen.getByText(COMPANY.about.history)).toBeInTheDocument();
+    expect(screen.getByText(COMPANY.contact.email)).toBeInTheDocument();
+  });
+});
+
+describe('GameLoader', () => {
+  it('shows start-up progress as a percentage', () => {
+    render(<GameLoader nodes={{ loading: { progress: 0.42 } }} />);
+    expect(screen.getByRole('progressbar')).toHaveAttribute('aria-valuenow', '42');
+  });
+});

src/pages/game/GameSurfaces.jsx

@@ -1,5 +1,4 @@
 import { GameNode } from '@/components/shared/GameNode.jsx';
-import { strings } from '@/i18n/fa.js';
 /** @typedef {{nodes:object,actions:object}} GameSurfacesProps */
 /** Presents the GameSurfaces view using plain models and semantic native elements.
  * @param {GameSurfacesProps} props - Interface snapshots and callbacks.
@@ -18,9 +17,6 @@ export function GameSurfaces({ nodes }) {
         model={nodes['camera']}
       ></GameNode>
       <GameNode as="canvas" id="world" model={nodes['world']} />
-      <GameNode as="div" id="loading" model={nodes['loading']}>
-        {strings.app.buildingCity}
-      </GameNode>
     </>
   );
 }

src/routes/AppRoutes.jsx

@@ -1,15 +1,21 @@
-import { Suspense, lazy } from 'react';
-import { strings } from '@/i18n/fa.js';
-const GamePage = lazy(() =>
-  import('@/pages/game/GamePage.jsx').then((module) => ({
-    default: module.GamePage,
-  })),
-);
-/** Loads the one game page on demand while keeping a visible startup status. */
+import { CompanyGame } from '@/pages/game/CompanyGame.jsx';
+import { START_MODES } from '@/constants/startModes.js';
+
+/**
+ * Reads the embedding options from the address: `?mode=about` starts in a mode, `?poster` shows
+ * the light poster first. An iframe on the company site can set them in its src.
+ * @returns {{startMode?: string, showPoster: boolean}} CompanyGame props.
+ */
+function optionsFromUrl() {
+  const params = new URLSearchParams(location.search);
+  const mode = params.get('mode');
+  return {
+    startMode: START_MODES.includes(mode) ? mode : undefined,
+    showPoster: params.has('poster'),
+  };
+}
+
+/** The app has one page: the company game, configured from the address. */
 export function AppRoutes() {
-  return (
-    <Suspense fallback={<p role="status">{strings.app.preparing}</p>}>
-      <GamePage />
-    </Suspense>
-  );
+  return <CompanyGame {...optionsFromUrl()} />;
 }

src/utils/seoSummary.js

@@ -0,0 +1,78 @@
+import { COMPANY } from '../config/company.js';
+import { strings } from '../i18n/fa.js';
+
+// Builds the search-engine content written into index.html at build time (see vite.config.js):
+// the page title and description, a visually hidden Persian summary of the company and its
+// products, and Organization structured data. Crawlers read it without running the 3D game.
+
+/**
+ * Escapes text for use inside HTML.
+ * @param {string} text - Plain text.
+ * @returns {string} HTML-safe text.
+ */
+const escapeHtml = (text) =>
+  String(text).replace(
+    /[&<>"']/g,
+    (ch) => ({ '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;' })[ch],
+  );
+
+/**
+ * Title and description tags.
+ * @returns {string} HTML for the head.
+ */
+export function seoHead() {
+  return [
+    `<title>${escapeHtml(strings.seo.title)}</title>`,
+    `<meta name="description" content="${escapeHtml(strings.seo.description)}" />`,
+  ].join('\n    ');
+}
+
+/**
+ * Visually hidden summary of the company, its products and contact details.
+ * @returns {string} HTML for the body.
+ */
+export function seoSummary() {
+  const { contact, about, products } = COMPANY;
+  const items = products
+    .map((p) => `<li><h3>${escapeHtml(p.name)}</h3><p>${escapeHtml(p.description)}</p></li>`)
+    .join('');
+  const address = strings.landing.fullAddress(contact.address, contact.city);
+  return `<section class="sr-only" aria-label="${escapeHtml(strings.seo.summaryLabel)}">
+      <h1>${escapeHtml(COMPANY.name)}</h1>
+      <p>${escapeHtml(COMPANY.tagline)}</p>
+      <p>${escapeHtml(about.history)}</p>
+      <h2>${escapeHtml(strings.seo.productsHeading)}</h2>
+      <ul>${items}</ul>
+      <h2>${escapeHtml(strings.landing.sections.contact)}</h2>
+      <p>${escapeHtml(address)}</p>
+      <p>${escapeHtml(`${strings.landing.phone}: ${contact.phone}`)}</p>
+      <p>${escapeHtml(`${strings.landing.email}: ${contact.email}`)}</p>
+    </section>`;
+}
+
+/**
+ * Organization structured data (schema.org JSON-LD).
+ * @returns {string} Script tag.
+ */
+export function seoStructuredData() {
+  const { contact } = COMPANY;
+  const data = {
+    '@context': 'https://schema.org',
+    '@type': 'Organization',
+    name: COMPANY.name,
+    description: COMPANY.tagline,
+    url: contact.website,
+    email: contact.email,
+    telephone: contact.phone,
+    address: {
+      '@type': 'PostalAddress',
+      streetAddress: contact.address,
+      addressLocality: contact.city,
+      addressCountry: 'IR',
+    },
+    sameAs: contact.socials.map((social) => social.url),
+  };
+  // "<" is escaped so no value can close the script tag early.
+  const json = JSON.stringify(data).replace(/</g, '\\u003c');
+  return `<script type="application/ld+json">${json}</script>`;
+}

tests/seo.test.js

@@ -0,0 +1,25 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { COMPANY } from '../src/config/company.js';
+import { seoHead, seoStructuredData, seoSummary } from '../src/utils/seoSummary.js';
+
+test('The page head carries the company title and description', () => {
+  const head = seoHead();
+  assert.ok(head.includes(`<title>${COMPANY.name}`));
+  assert.match(head, /<meta name="description" content="[^"]+"/);
+});
+
+test('The hidden summary lists the company, every product and the contact details', () => {
+  const summary = seoSummary();
+  assert.ok(summary.startsWith('<section class="sr-only"'));
+  for (const product of COMPANY.products) assert.ok(summary.includes(product.name));
+  assert.ok(summary.includes(COMPANY.contact.email));
+});
+
+test('Structured data is valid JSON-LD for the organization', () => {
+  const json = seoStructuredData().replace(/^<script[^>]*>|<\/script>$/g, '');
+  const data = JSON.parse(json);
+  assert.equal(data['@type'], 'Organization');
+  assert.equal(data.name, COMPANY.name);
+  assert.equal(data.address.addressLocality, COMPANY.contact.city);
+});

vite.config.js

@@ -4,6 +4,7 @@ import { defineConfig } from 'vite';
 import { readdirSync, statSync } from 'node:fs';
 import { join, relative } from 'node:path';
 import { createHash } from 'node:crypto';
+import { seoHead, seoStructuredData, seoSummary } from './src/utils/seoSummary.js';
 
 const listFiles = (dir) =>
   readdirSync(dir).flatMap((name) => {
@@ -62,11 +63,23 @@ self.addEventListener('fetch', event => {
   };
 }
 
+// Writes the company's title, description, structured data and a hidden Persian summary into
+// index.html, so search engines and link previews see real content without running the game.
+function companySeo() {
+  return {
+    name: 'company-seo',
+    transformIndexHtml: (html) =>
+      html
+        .replace('<!--seo-head-->', `${seoHead()}\n    ${seoStructuredData()}`)
+        .replace('<!--seo-summary-->', seoSummary()),
+  };
+}
+
 export default defineConfig({
   // Relative assets also load under a GitHub Pages repository path.
   base: './',
   resolve: { alias: { '@': fileURLToPath(new URL('./src', import.meta.url)) } },
-  plugins: [react(), offlineServiceWorker()],
+  plugins: [react(), companySeo(), offlineServiceWorker()],
   // Top-level await loads the building and imagery files before the world is built.
   build: { target: 'es2022' },
   server: {