diff --git a/changelog.html b/changelog.html
index ba94633..f20db81 100644
--- a/changelog.html
+++ b/changelog.html
@@ -19,12 +19,14 @@
       content="Verified updates to Chess Coach browser-based chess practice, reliability, and learning."
     />
     <meta property="og:url" content="https://chess.significanthobbies.com/changelog" />
-    <meta name="twitter:card" content="summary" />
+    <meta property="og:image" content="https://chess.significanthobbies.com/og-image.svg" />
+    <meta name="twitter:card" content="summary_large_image" />
     <meta name="twitter:title" content="Changelog · Chess Coach" />
     <meta
       name="twitter:description"
       content="Verified updates to Chess Coach browser-based chess practice, reliability, and learning."
     />
+    <meta name="twitter:image" content="https://chess.significanthobbies.com/og-image.svg" />
     <style>
       html { scrollbar-gutter: stable; background-color: #1a1a2e; }
       body { margin: 0; background-color: #1a1a2e; }
diff --git a/docs/operations/agent-indexing.md b/docs/operations/agent-indexing.md
index 6dbae7f..c44b5a3 100644
--- a/docs/operations/agent-indexing.md
+++ b/docs/operations/agent-indexing.md
@@ -19,7 +19,9 @@ mirror into these files.
 | `public/llms-full.txt` | Longer agent brief — product blurb + full surface list + fleet/contact. |
 | `public/api-ai.json` | JSON inventory of public surfaces (name, version, url, llms, sitemap, robots, markdown negotiation, auth notes). |
 | `public/index.md` | Markdown product brief (no JS) — the "markdown negotiation" surface. |
-| `public/sitemap.xml` | `/`, `/faq`, `/index.md`, `/llms.txt`. |
+| `public/faq.md` | Markdown counterpart for the public FAQ. |
+| `public/changelog.md` | Markdown counterpart for the public changelog. |
+| `public/sitemap.xml` | Public HTML routes only: `/`, `/faq`, `/changelog`. |
 | `public/robots.txt` | Allow all + sitemap + explicit allow for agent surfaces. |
 | `public/_redirects` | Cloudflare Pages rewrite: `/api/ai` → `/api-ai.json` (200). |
 | `public/fa7259e2e0d942f1a1267b344a75a143.txt` | IndexNow key file (Bing/Yandex URL submission). |
diff --git a/faq.html b/faq.html
index e12d6c9..f283e65 100644
--- a/faq.html
+++ b/faq.html
@@ -13,9 +13,11 @@
     <meta property="og:title" content="FAQ — Chess Coach" />
     <meta property="og:description" content="Play chess against Stockfish with AI-powered move coaching and analysis. No account required." />
     <meta property="og:url" content="https://chess.significanthobbies.com/faq" />
+    <meta property="og:image" content="https://chess.significanthobbies.com/og-image.svg" />
     <meta name="twitter:card" content="summary_large_image" />
     <meta name="twitter:title" content="FAQ — Chess Coach" />
     <meta name="twitter:description" content="Play chess against Stockfish with AI-powered move coaching and analysis. No account required." />
+    <meta name="twitter:image" content="https://chess.significanthobbies.com/og-image.svg" />
     <style>
       :root {
         --bg: #1a1a2e;
diff --git a/index.html b/index.html
index 5c2cd27..515435f 100644
--- a/index.html
+++ b/index.html
@@ -14,9 +14,11 @@
     <meta property="og:type" content="website" />
     <meta property="og:url" content="https://chess.significanthobbies.com/" />
     <meta property="og:site_name" content="Chess Coach" />
-    <meta name="twitter:card" content="summary" />
+    <meta property="og:image" content="https://chess.significanthobbies.com/og-image.svg" />
+    <meta name="twitter:card" content="summary_large_image" />
     <meta name="twitter:title" content="Chess Coach — Play Stockfish with AI Coaching" />
     <meta name="twitter:description" content="Play chess against Stockfish with AI-powered coaching feedback." />
+    <meta name="twitter:image" content="https://chess.significanthobbies.com/og-image.svg" />
     <!-- Critical inline styles: applied immediately, not deferred like the Tailwind stylesheet -->
     <style>
       html { scrollbar-gutter: stable; background-color: #1a1a2e; }
diff --git a/public/api-ai.json b/public/api-ai.json
index 5ac3b4c..96a1935 100644
--- a/public/api-ai.json
+++ b/public/api-ai.json
@@ -17,10 +17,24 @@
       "md": "https://chess.significanthobbies.com/index.md",
       "kind": "spa",
       "description": "Product home"
+    },
+    {
+      "id": "faq",
+      "url": "https://chess.significanthobbies.com/faq",
+      "md": "https://chess.significanthobbies.com/faq.md",
+      "kind": "static",
+      "description": "Engine, coaching, privacy, and pricing questions"
+    },
+    {
+      "id": "changelog",
+      "url": "https://chess.significanthobbies.com/changelog",
+      "md": "https://chess.significanthobbies.com/changelog.md",
+      "kind": "static",
+      "description": "Verified reliability, discovery, and learning updates"
     }
   ],
   "auth": {
     "public": true,
-    "notes": "Auth-walled app routes are not agent-indexed unless listed here."
+    "notes": "The public game requires no account. The development-only AI proxy is excluded."
   }
 }
diff --git a/public/changelog.md b/public/changelog.md
new file mode 100644
index 0000000..9bcaf20
--- /dev/null
+++ b/public/changelog.md
@@ -0,0 +1,26 @@
+# Chess Coach changelog
+
+Verified updates to browser-based chess practice, reliability, and learning.
+
+## July 26, 2026 — Reliable Stockfish startup
+
+- Cloudflare Pages now serves the cross-origin isolation headers required by
+  Stockfish WebAssembly.
+- The static public deployment remains independent of the optional local AI
+  bridge.
+
+## July 25, 2026 — Better search and sharing context
+
+- Chess Coach gained canonical, social, and structured metadata.
+- Public agent and crawler surfaces describe the game without exposing the
+  development-only AI proxy.
+
+## April 26, 2026 — A focused chess-practice board
+
+- The responsive board, evaluation, move feedback, clock, and coaching layout
+  reached their current form.
+- Six Stockfish levels, hints, undo, board flip, and local persistence remain
+  available without an account.
+
+- [Roadmap](https://github.com/Significant-Hobbies/chess/issues)
+- [Source](https://github.com/Significant-Hobbies/chess)
diff --git a/public/faq.md b/public/faq.md
new file mode 100644
index 0000000..b904bba
--- /dev/null
+++ b/public/faq.md
@@ -0,0 +1,46 @@
+# Chess Coach FAQ
+
+Chess Coach combines a browser-local Stockfish 18 engine with optional,
+on-demand AI explanations. No account is required.
+
+## What does Chess Coach provide?
+
+- Six Stockfish difficulty levels
+- Real-time evaluation from White's perspective
+- Move-quality badges based on centipawn loss
+- Best-move hints, undo, board flip, and configurable clocks
+- Local game persistence across page reloads
+- Optional natural-language coaching after a move
+
+## Does Stockfish run locally?
+
+Yes. Stockfish runs as WebAssembly inside a Web Worker in the browser. Engine
+analysis does not require a server queue or upload the game.
+
+## How are moves classified?
+
+Chess Coach compares the played move with Stockfish's best line and uses the
+centipawn loss to label it Best, Good, Inaccuracy, Mistake, or Blunder.
+
+## How do AI explanations work?
+
+The user explicitly requests an explanation from the Coach panel. The prompt
+includes the position, played move, evaluation change, and engine alternative.
+Cloud providers require the user's own configured key. Local CLI providers are
+available only through the development bridge and are not part of the static
+public deployment.
+
+## Is Chess Coach free?
+
+The game, Stockfish analysis, evaluation bar, hints, and move-quality feedback
+are free and require no account. A cloud AI provider may charge for explanations
+requested with a user-supplied key.
+
+## Can a game be paused?
+
+The current game is saved in local storage, so a practice session can continue
+after a page reload.
+
+- [Play Chess Coach](https://chess.significanthobbies.com/)
+- [Read the changelog](https://chess.significanthobbies.com/changelog)
+- [View the source](https://github.com/Significant-Hobbies/chess)
diff --git a/public/index.md b/public/index.md
index 97f7d43..b3cf67e 100644
--- a/public/index.md
+++ b/public/index.md
@@ -1,12 +1,27 @@
 # Chess Coach
 
-AI-coached chess practice in the browser.
+Browser-based chess practice against Stockfish 18 with optional, on-demand AI
+explanations.
 
-## Note for agents
+## What is included
 
-The app is a client SPA with little server-rendered copy. Use this brief and `/api/ai` (when deployed with a worker) rather than HTML shell scraping.
+- Six engine levels, configurable clocks, hints, undo, and board flip
+- Real-time evaluation and move-quality badges
+- Local game persistence with no account
+- Optional explanations from a configured cloud provider or a local development
+  bridge
+
+Stockfish runs locally in a Web Worker. The static production deployment does
+not expose the development-only AI proxy.
+
+## Public pages
+
+- [Play](https://chess.significanthobbies.com/)
+- [FAQ](https://chess.significanthobbies.com/faq)
+- [Changelog](https://chess.significanthobbies.com/changelog)
 
 ## Agent entrypoints
 
 - https://chess.significanthobbies.com/llms.txt
 - https://chess.significanthobbies.com/index.md
+- https://chess.significanthobbies.com/api/ai
diff --git a/public/llms-full.txt b/public/llms-full.txt
index 3850b09..20f8e0d 100644
--- a/public/llms-full.txt
+++ b/public/llms-full.txt
@@ -20,6 +20,8 @@ The app is a client SPA with little server-rendered copy. Use this brief and `/a
 ## Product links
 
 - Home: https://chess.significanthobbies.com/ — Play (SPA)
+- FAQ: https://chess.significanthobbies.com/faq — Engine, coaching, and privacy questions
+- Changelog: https://chess.significanthobbies.com/changelog — Verified product updates
 
 ## Machine surfaces
 
diff --git a/public/og-image.svg b/public/og-image.svg
new file mode 100644
index 0000000..aeddadd
--- /dev/null
+++ b/public/og-image.svg
@@ -0,0 +1,10 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="1200" height="630" viewBox="0 0 1200 630" role="img" aria-labelledby="title description">
+  <title id="title">Chess Coach</title>
+  <desc id="description">Play Stockfish with optional AI coaching</desc>
+  <rect width="1200" height="630" fill="#1a1a2e"/>
+  <rect x="70" y="70" width="1060" height="490" rx="28" fill="#20203a" stroke="#374151" stroke-width="4"/>
+  <text x="120" y="295" fill="#fbbf24" font-family="Georgia, serif" font-size="108">♞</text>
+  <text x="270" y="285" fill="#f3f4f6" font-family="system-ui, sans-serif" font-size="92" font-weight="700">Chess Coach</text>
+  <text x="276" y="372" fill="#d1d5db" font-family="system-ui, sans-serif" font-size="42">Play Stockfish with optional AI coaching</text>
+  <text x="276" y="452" fill="#9ca3af" font-family="system-ui, sans-serif" font-size="30">Local engine · Move feedback · No account</text>
+</svg>
diff --git a/public/sitemap.xml b/public/sitemap.xml
index 0080ff5..fab8d28 100644
--- a/public/sitemap.xml
+++ b/public/sitemap.xml
@@ -3,6 +3,4 @@
   <url><loc>https://chess.significanthobbies.com/</loc></url>
   <url><loc>https://chess.significanthobbies.com/faq</loc></url>
   <url><loc>https://chess.significanthobbies.com/changelog</loc></url>
-  <url><loc>https://chess.significanthobbies.com/index.md</loc></url>
-  <url><loc>https://chess.significanthobbies.com/llms.txt</loc></url>
 </urlset>