diff --git a/apps/marketing/index.html b/apps/marketing/index.html
index b4d8f3d6..5c58cf30 100644
--- a/apps/marketing/index.html
+++ b/apps/marketing/index.html
@@ -16,6 +16,35 @@
       name="description"
       content="PARTHA turns a repository revision into one sealed, queryable model and uses it to explain architecture, dependencies, review findings, insights, and documentation. See a scripted walkthrough, or run it yourself."
     />
+    <!-- Open Graph / social preview (#512): shared links to partha.uk render
+         as a summary card with the labyrinth mark and this tagline instead of
+         a bare title. The image ships below at apps/marketing/public/partha-og.png. -->
+    <meta property="og:site_name" content="PARTHA" />
+    <meta property="og:title" content="PARTHA" />
+    <meta
+      property="og:description"
+      content="PARTHA turns a repository revision into one sealed, queryable model and uses it to explain architecture, dependencies, review findings, insights, and documentation."
+    />
+    <meta property="og:type" content="website" />
+    <meta property="og:url" content="https://www.partha.uk/" />
+    <meta property="og:image" content="https://www.partha.uk/partha-og.png" />
+    <meta property="og:image:width" content="1200" />
+    <meta property="og:image:height" content="630" />
+    <meta
+      property="og:image:alt"
+      content="PARTHA — turn a repository revision into one sealed, queryable model."
+    />
+    <meta name="twitter:card" content="summary_large_image" />
+    <meta name="twitter:title" content="PARTHA" />
+    <meta
+      name="twitter:description"
+      content="PARTHA turns a repository revision into one sealed, queryable model and uses it to explain architecture, dependencies, review findings, insights, and documentation."
+    />
+    <meta name="twitter:image" content="https://www.partha.uk/partha-og.png" />
+    <meta
+      name="twitter:image:alt"
+      content="PARTHA — turn a repository revision into one sealed, queryable model."
+    />
     <title>PARTHA</title>
     <link rel="preconnect" href="https://fonts.googleapis.com" />
     <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin />
diff --git a/apps/marketing/public/partha-og.png b/apps/marketing/public/partha-og.png
new file mode 100644
index 00000000..4449ed5b
Binary files /dev/null and b/apps/marketing/public/partha-og.png differ