diff --git a/README.adoc b/README.adoc
index 6997aec9..a492701c 100644
--- a/README.adoc
+++ b/README.adoc
@@ -4,6 +4,8 @@
 :idprefix:
 :idseparator: -
 
+image::site/assets/favicon.svg[BoJ Server mark,96,96]
+
 *One MCP endpoint for the WHOLE toolchain* — GitHub, GitLab, Cloudflare, Vercel, Verpex, Gmail, Calendar, browser automation, research, ML, multi-agent coordination, and a large catalogue of pluggable domain cartridges, all reachable through a single zero-dependency stdio bridge.
 
 [cols="1s,4",frame=none,grid=none]
diff --git a/README.md b/README.md
index b78bb3c5..78f39a60 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,10 @@
 <!-- SPDX-License-Identifier: CC-BY-SA-4.0 -->
 <!-- GENERATED from README.adoc by standards/.github/workflows/readme-derive-reusable.yml — do not edit. -->
 
+<figure>
+<img src="site/assets/favicon.svg" alt="BoJ Server mark" />
+</figure>
+
 **One MCP endpoint for the WHOLE toolchain** — GitHub, GitLab, Cloudflare, Vercel, Verpex, Gmail, Calendar, browser automation, research, ML, multi-agent coordination, and a large catalogue of pluggable domain cartridges, all reachable through a single zero-dependency stdio bridge.
 
 | Published | [![npm](https://img.shields.io/npm/v/@hyperpolymath/boj-server?logo=npm)](https://www.npmjs.com/package/@hyperpolymath/boj-server) [![Software Heritage](https://img.shields.io/badge/SWH-Archived-blue?logo=softwareheritage)](https://archive.softwareheritage.org/browse/origin/?origin_url=https://github.com/hyperpolymath/boj-server) [![Boj Server MCP score](https://aiagentslisting.com/boj-server/badge.svg?variant=score)](https://aiagentslisting.com/mcp/boj-server) |
diff --git a/docs/website/CLOUDFLARE-SETUP.adoc b/docs/website/CLOUDFLARE-SETUP.adoc
index 51255c81..39cc8d1f 100644
--- a/docs/website/CLOUDFLARE-SETUP.adoc
+++ b/docs/website/CLOUDFLARE-SETUP.adoc
@@ -15,7 +15,7 @@ generated from the canonical registry.
 [cols="1,3"]
 |===
 | `site/index.html`        | The hub: hero, install configurator, catalogue browser, capabilities.
-| `site/assets/`           | `style.css`, `app.js` (vanilla, zero-dependency), `favicon.svg`.
+| `site/assets/`           | `style.css`, `app.js` (vanilla, zero-dependency), `favicon.svg` (the BoJ mark), `social-preview.svg` + `.png` (1280×640 GitHub / Open Graph card).
 | `site/catalog.json`      | Snapshot of the registry (139 cartridges). Regenerate — see below.
 | `site/_headers`          | Strict security headers (HSTS, CSP, etc.) in Pages format.
 | `site/_redirects`        | `www` -> apex canonicalisation + convenience deep-links.
diff --git a/site/README.adoc b/site/README.adoc
index 16906c65..9adb0e6f 100644
--- a/site/README.adoc
+++ b/site/README.adoc
@@ -7,7 +7,7 @@ A no-build static bundle served by Cloudflare Pages from this directory.
 
 * `index.html` — hub: install configurator (base + NeSy / Agentic / Coordination
   bundles) and a browsable catalogue of all 139 cartridges.
-* `assets/` — `style.css`, `app.js` (vanilla, zero-dependency), `favicon.svg`.
+* `assets/` — `style.css`, `app.js` (vanilla, zero-dependency), `favicon.svg` (the BoJ mark), `social-preview.svg` + `.png` (1280×640 GitHub / Open Graph card).
 * `catalog.json` — registry snapshot read by `app.js`. Regenerate with
   `tools/site-catalog/build-catalog.sh`.
 * `_headers`, `_redirects`, `CNAME`, `robots.txt`, `sitemap.xml`, `.well-known/`.
diff --git a/site/assets/favicon.svg b/site/assets/favicon.svg
index ba8fba63..4d678482 100644
--- a/site/assets/favicon.svg
+++ b/site/assets/favicon.svg
@@ -1,7 +1,13 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64" role="img" aria-label="BoJ">
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64" width="96" height="96" role="img" aria-label="BoJ Server">
   <!-- SPDX-License-Identifier: MPL-2.0 -->
+  <!-- BoJ mark: JSON-RPC braces holding a stack of cartridges. -->
   <rect width="64" height="64" rx="14" fill="#0d1117"/>
-  <rect x="3" y="3" width="58" height="58" rx="12" fill="none" stroke="#30363d" stroke-width="2"/>
-  <text x="32" y="42" font-family="JetBrains Mono, ui-monospace, monospace" font-size="26"
-        font-weight="700" fill="#58a6ff" text-anchor="middle">BoJ</text>
+  <rect x="1.5" y="1.5" width="61" height="61" rx="12.5" fill="none" stroke="#30363d" stroke-width="2"/>
+  <g transform="translate(7.04 7.04) scale(.78)">
+    <path d="M18 8 Q10 8 10 16 V26 Q10 32 4 32 Q10 32 10 38 V48 Q10 56 18 56" fill="none" stroke="#c9d1d9" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
+    <path d="M46 8 Q54 8 54 16 V26 Q54 32 60 32 Q54 32 54 38 V48 Q54 56 46 56" fill="none" stroke="#c9d1d9" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
+    <rect x="20" y="17" width="24" height="8" rx="2.5" fill="#58a6ff"/>
+    <rect x="20" y="28" width="24" height="8" rx="2.5" fill="#a78bfa"/>
+    <rect x="20" y="39" width="24" height="8" rx="2.5" fill="#58a6ff" opacity=".7"/>
+  </g>
 </svg>
diff --git a/site/assets/social-preview.png b/site/assets/social-preview.png
new file mode 100644
index 00000000..4d8d4a7a
Binary files /dev/null and b/site/assets/social-preview.png differ
diff --git a/site/assets/social-preview.svg b/site/assets/social-preview.svg
new file mode 100644
index 00000000..4dfda0d0
--- /dev/null
+++ b/site/assets/social-preview.svg
@@ -0,0 +1,19 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1280 640" width="1280" height="640" role="img" aria-label="BoJ Server: one MCP endpoint for the whole toolchain">
+  <!-- SPDX-License-Identifier: MPL-2.0 -->
+  <!-- GitHub social preview source. Render to social-preview.png (1280x640) and upload under Settings > General > Social preview. -->
+  <rect width="1280" height="640" fill="#0d1117"/>
+  <rect x="20" y="20" width="1240" height="600" rx="28" fill="none" stroke="#21262d" stroke-width="2"/>
+  <g transform="translate(120 160) scale(5)">
+    <path d="M18 8 Q10 8 10 16 V26 Q10 32 4 32 Q10 32 10 38 V48 Q10 56 18 56" fill="none" stroke="#c9d1d9" stroke-width="4" stroke-linecap="round" stroke-linejoin="round"/>
+    <path d="M46 8 Q54 8 54 16 V26 Q54 32 60 32 Q54 32 54 38 V48 Q54 56 46 56" fill="none" stroke="#c9d1d9" stroke-width="4" stroke-linecap="round" stroke-linejoin="round"/>
+    <rect x="20" y="17" width="24" height="8" rx="2.5" fill="#58a6ff"/>
+    <rect x="20" y="28" width="24" height="8" rx="2.5" fill="#a78bfa"/>
+    <rect x="20" y="39" width="24" height="8" rx="2.5" fill="#58a6ff" opacity=".7"/>
+  </g>
+  <g font-family="JetBrains Mono, ui-monospace, SFMono-Regular, Menlo, monospace">
+    <text x="530" y="290" font-size="92" font-weight="700" fill="#e6edf3">BoJ Server</text>
+    <text x="532" y="350" font-family="IBM Plex Sans, system-ui, sans-serif" font-size="34" fill="#8b949e">One MCP endpoint for the whole toolchain</text>
+    <text x="532" y="420" font-size="26" fill="#58a6ff">zero dependencies · Idris2-verified ABI</text>
+    <text x="532" y="540" font-size="22" fill="#6e7681">github.com/hyperpolymath/boj-server</text>
+  </g>
+</svg>
diff --git a/site/index.html b/site/index.html
index 9ae76b2a..14b60171 100644
--- a/site/index.html
+++ b/site/index.html
@@ -15,6 +15,11 @@
   <meta property="og:title" content="boj-server — one MCP endpoint for all your tooling">
   <meta property="og:description" content="Configure a BoJ install (base + NeSy / Agentic / Coordination bundles) and browse 139 open-source MCP cartridges.">
   <meta property="og:url" content="https://boj-server.net/">
+  <meta property="og:image" content="https://boj-server.net/assets/social-preview.png">
+  <meta property="og:image:width" content="1280">
+  <meta property="og:image:height" content="640">
+  <meta property="og:image:alt" content="BoJ Server mark: braces around a stack of cartridges">
+  <meta name="twitter:card" content="summary_large_image">
   <meta name="theme-color" content="#0d1117">
   <link rel="icon" href="/assets/favicon.svg" type="image/svg+xml">
   <link rel="stylesheet" href="/assets/style.css">