--- a/base/index.html
+++ b/head/index.html
@@ -288,6 +288,7 @@
 <ul>
 <li><code>application/a2a-agent-card+json</code> — an A2A Agent Card</li>
 <li><code>application/mcp-server-card+json</code> — an MCP Server Card</li>
+<li><code>application/mcp-server+json</code> — an MCP Registry <code>server.json</code> document</li>
 <li><code>application/agent-skills+json</code> — Agent Skill Metadata json file</li>
 <li><code>application/agent-skills+md</code> — an Agent Skill defined in a standard Markdown file (the suffix <code>+md</code> is to be registered)</li>
 <li><code>application/agent-skills+zip</code> — an Agent Skill bundle (ZIP archive)</li>
@@ -1811,7 +1812,8 @@
 <p>A Server Card is a static discovery document for a single HTTP-based MCP
 server (its identity and connection details). It is distinct from the MCP
 Registry's <code>server.json</code>, an installable-package descriptor — a separate
-artifact type that this appendix does not address.</p>
+artifact type mapped in
+<a href="#mapping-to-mcp-registry-server-json">Mapping to MCP Registry server.json</a>.</p>
 <section id="overview">
 <h2>Overview</h2>
 <p>An MCP Server Card is a static discovery document for an individual
@@ -2023,6 +2025,212 @@
 </ol>
 </section>
 </section>
+<section class="appendix" id="mapping-to-mcp-registry-server-json">
+<h1>Mapping to MCP Registry server.json</h1>
+<p>This appendix describes how the MCP Registry <code>server.json</code> format
+(see <a href="https://github.com/modelcontextprotocol/registry">modelcontextprotocol/registry</a>)
+maps to AI Catalog as a <strong>first-class cataloged artifact type</strong>, enabling
+installable MCP servers to be discovered alongside other AI artifacts
+through a unified catalog.</p>
+<blockquote>
+<p><strong>Two MCP server artifacts, two types.</strong> The MCP ecosystem defines two
+distinct documents for a server, and AI Catalog gives each its own known
+<code>type</code>:</p>
+<ul>
+<li><strong>MCP Server Card</strong> (<code>application/mcp-server-card+json</code>) — a static
+  discovery document for a connectable HTTP server (identity, transport,
+  capabilities, auth). See <a href="#mapping-to-mcp-servers">Mapping to MCP Servers</a>.</li>
+<li><strong>MCP Registry <code>server.json</code></strong> (<code>application/mcp-server+json</code>) — an
+  installable <strong>package descriptor</strong> (package coordinates, transports,
+  environment variables, CLI arguments).</li>
+</ul>
+<p>These are different artifacts, so they use different media types. The
+Server Card deliberately uses <code>application/mcp-server-card+json</code> (not
+<code>application/mcp-server+json</code>) to leave the unqualified <code>mcp-server</code>
+name for the Registry <code>server.json</code> document
+(modelcontextprotocol/experimental-ext-server-card issue #9 / PR #18).
+A catalog entry references whichever artifact fits the use case — a
+<code>server.json</code> for installable packages, a Server Card for connectable
+endpoints — and a domain MAY list both.</p>
+</blockquote>
+<section id="overview-2">
+<h2>Overview</h2>
+<p>The MCP Registry defines a <code>server.json</code> format for describing MCP
+servers. Each <code>server.json</code> document captures everything needed to
+install, configure, and connect to a single MCP server: package
+coordinates (npm, PyPI, NuGet, OCI), remote endpoints (streamable-http,
+SSE), transport configuration, environment variables, and CLI arguments.</p>
+<p>In AI Catalog terms, a <code>server.json</code> document is the <strong>artifact
+content</strong> — the native metadata that a Catalog Entry references, declared
+with the known type <code>application/mcp-server+json</code>. AI Catalog does not
+duplicate or redefine <code>server.json</code> fields; it provides the discovery and
+trust layer that <code>server.json</code> does not address.</p>
+</section>
+<section id="conceptual-mapping-3">
+<h2>Conceptual Mapping</h2>
+<table>
+<thead>
+<tr>
+<th style="text-align: left;">MCP <code>server.json</code></th>
+<th style="text-align: left;">AI Catalog Equivalent</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td style="text-align: left;"><code>server.json</code> document (whole file)</td>
+<td style="text-align: left;">Artifact content via entry <code>url</code> (type <code>application/mcp-server+json</code>) or <code>data</code></td>
+</tr>
+<tr>
+<td style="text-align: left;"><code>name</code> (reverse-DNS identifier)</td>
+<td style="text-align: left;">Entry <code>identifier</code> (mapped to the <a href="https://github.com/Agent-Card/ai-catalog/blob/main/adr/0015-agent-identifier-naming.md"><code>urn:air:{publisher}:{namespace}:{name}</code></a> URN form — e.g. registry name <code>com.pulsemcp/remote-filesystem</code> → <code>urn:air:pulsemcp.com:mcp:remote-filesystem</code>). The mapping is not a mechanical transliteration: <code>publisher</code> is the publisher's actual domain (e.g. <code>pulsemcp.com</code>) and <code>namespace</code> is a chosen category (e.g. <code>mcp</code>), independent of the registry name's reverse-DNS segments.</td>
+</tr>
+<tr>
+<td style="text-align: left;"><code>title</code></td>
+<td style="text-align: left;">Stays in the artifact (<code>server.json</code> carries its own <code>title</code>); entry <code>displayName</code> is omitted unless the artifact lacks a name</td>
+</tr>
+<tr>
+<td style="text-align: left;"><code>description</code></td>
+<td style="text-align: left;">Entry <code>description</code></td>
+</tr>
+<tr>
+<td style="text-align: left;"><code>version</code></td>
+<td style="text-align: left;">Entry <code>version</code></td>
+</tr>
+<tr>
+<td style="text-align: left;"><code>repository</code></td>
+<td style="text-align: left;">Entry <code>metadata.repository</code></td>
+</tr>
+<tr>
+<td style="text-align: left;"><code>packages[]</code> (npm, pypi, nuget, oci)</td>
+<td style="text-align: left;">Inside the artifact — not surfaced in the catalog</td>
+</tr>
+<tr>
+<td style="text-align: left;"><code>remotes[]</code> (streamable-http, sse)</td>
+<td style="text-align: left;">Inside the artifact — not surfaced in the catalog</td>
+</tr>
+<tr>
+<td style="text-align: left;"><code>environmentVariables[]</code></td>
+<td style="text-align: left;">Inside the artifact — not surfaced in the catalog</td>
+</tr>
+<tr>
+<td style="text-align: left;"><code>_meta</code></td>
+<td style="text-align: left;">Entry <code>metadata</code> for catalog-level hints; otherwise stays in the artifact</td>
+</tr>
+<tr>
+<td style="text-align: left;"><em>(not in server.json)</em></td>
+<td style="text-align: left;">Entry <code>publisher</code></td>
+</tr>
+<tr>
+<td style="text-align: left;"><em>(not in server.json)</em></td>
+<td style="text-align: left;">Entry <code>trustManifest</code> (identity, attestations, provenance)</td>
+</tr>
+<tr>
+<td style="text-align: left;"><em>(not in server.json)</em></td>
+<td style="text-align: left;">Entry <code>tags</code> for cross-artifact discovery</td>
+</tr>
+</tbody>
+</table>
+</section>
+<section id="mcp-server-as-catalog-entry-2">
+<h2>MCP Server as Catalog Entry</h2>
+<p>An MCP server published as a Registry <code>server.json</code> maps to a Catalog
+Entry whose <code>url</code> points to the <code>server.json</code> document and whose <code>type</code>
+is the known type <code>application/mcp-server+json</code>:</p>
+<pre><code class="language-json">{
+  &quot;identifier&quot;: &quot;urn:air:pulsemcp.com:mcp:remote-filesystem&quot;,
+  &quot;version&quot;: &quot;0.1.5&quot;,
+  &quot;type&quot;: &quot;application/mcp-server+json&quot;,
+  &quot;url&quot;: &quot;https://registry.modelcontextprotocol.io/v0/servers/com.pulsemcp%2Fremote-filesystem/versions/0.1.5&quot;,
+  &quot;description&quot;: &quot;MCP server for remote filesystem operations on cloud storage&quot;,
+  &quot;tags&quot;: [&quot;filesystem&quot;, &quot;storage&quot;],
+  &quot;publisher&quot;: {
+    &quot;identifier&quot;: &quot;did:web:pulsemcp.com&quot;,
+    &quot;displayName&quot;: &quot;PulseMCP&quot;
+  },
+  &quot;trustManifest&quot;: {
+    &quot;identity&quot;: &quot;urn:air:pulsemcp.com:mcp:remote-filesystem&quot;,
+    &quot;attestations&quot;: [
+      {
+        &quot;type&quot;: &quot;publisher-identity&quot;,
+        &quot;uri&quot;: &quot;https://trust.pulsemcp.com/certs/publisher.jwt&quot;
+      }
+    ],
+    &quot;provenance&quot;: [
+      {
+        &quot;relation&quot;: &quot;publishedFrom&quot;,
+        &quot;sourceId&quot;: &quot;https://github.com/pulsemcp/mcp-servers&quot;,
+        &quot;registryUri&quot;: &quot;https://registry.npmjs.org&quot;
+      }
+    ]
+  },
+  &quot;metadata&quot;: {
+    &quot;repository&quot;: &quot;https://github.com/pulsemcp/mcp-servers&quot;
+  },
+  &quot;updatedAt&quot;: &quot;2026-03-15T10:00:00Z&quot;
+}
+</code></pre>
+<p>The <code>url</code> resolves to the server's <code>server.json</code>. In the MCP Registry, a
+specific version is addressed as
+<code>/v0/servers/{name}/versions/{version}</code> — where <code>{name}</code> is the server's
+reverse-DNS registry name, URL-encoded (the <code>/</code> between namespace and
+name becomes <code>%2F</code>) — and the response carries the <code>server.json</code> document
+in its <code>server</code> field alongside registry <code>_meta</code>. A client fetches the
+catalog entry for discovery and trust evaluation, then retrieves the
+<code>server.json</code> for operational details (packages, transports, env vars).</p>
+</section>
+<section id="mcp-registry-as-ai-catalog">
+<h2>MCP Registry as AI Catalog</h2>
+<p>The MCP Registry — a centralized index of MCP servers — can be
+represented as an AI Catalog. This lets clients that understand
+<code>application/ai-catalog+json</code> discover installable MCP servers alongside
+A2A agents, skills, and other artifacts:</p>
+<pre><code class="language-json">{
+  &quot;specVersion&quot;: &quot;1.0&quot;,
+  &quot;host&quot;: {
+    &quot;displayName&quot;: &quot;MCP Server Registry&quot;,
+    &quot;identifier&quot;: &quot;did:web:modelcontextprotocol.io&quot;,
+    &quot;documentationUrl&quot;: &quot;https://modelcontextprotocol.io/docs&quot;
+  },
+  &quot;entries&quot;: [
+    {
+      &quot;identifier&quot;: &quot;urn:air:pulsemcp.com:mcp:remote-filesystem&quot;,
+      &quot;version&quot;: &quot;0.1.5&quot;,
+      &quot;type&quot;: &quot;application/mcp-server+json&quot;,
+      &quot;url&quot;: &quot;https://registry.modelcontextprotocol.io/v0/servers/com.pulsemcp%2Fremote-filesystem/versions/0.1.5&quot;,
+      &quot;description&quot;: &quot;MCP server for remote filesystem operations on cloud storage&quot;,
+      &quot;tags&quot;: [&quot;filesystem&quot;, &quot;storage&quot;]
+    },
+    {
+      &quot;identifier&quot;: &quot;urn:air:pulsemcp.com:mcp:pulse-fetch&quot;,
+      &quot;version&quot;: &quot;0.2.14&quot;,
+      &quot;type&quot;: &quot;application/mcp-server+json&quot;,
+      &quot;url&quot;: &quot;https://registry.modelcontextprotocol.io/v0/servers/com.pulsemcp.servers%2Fpulse-fetch/versions/0.2.14&quot;,
+      &quot;description&quot;: &quot;MCP server that extracts clean, structured content from web pages&quot;,
+      &quot;tags&quot;: [&quot;fetch&quot;, &quot;web&quot;]
+    }
+  ]
+}
+</code></pre>
+</section>
+<section id="relationship-to-mcp-server-cards">
+<h2>Relationship to MCP Server Cards</h2>
+<p>A Registry <code>server.json</code> and an MCP Server Card describe the same kind of
+thing at different lifecycle stages, and they layer naturally:</p>
+<dl>
+<dt><code>server.json</code> (<code>application/mcp-server+json</code>)</dt>
+<dd>How do I <strong>install and configure</strong> this server? What packages,
+  transports, arguments, and environment variables does it need?</dd>
+<dt>Server Card (<code>application/mcp-server-card+json</code>)</dt>
+<dd>How do I <strong>connect to and use</strong> this running server? What transport
+  endpoint, capabilities, tools, and authentication does it expose?</dd>
+</dl>
+<p>A domain MAY publish both as separate catalog entries — one entry of each
+<code>type</code> pointing at the respective artifact — so clients can pick the
+representation that matches what they are doing (provisioning vs.
+connecting). AI Catalog provides the trust and cross-ecosystem indexing
+layer over both; each artifact carries its own protocol-specific detail.</p>
+</section>
+</section>
 <section class="appendix" id="mapping-to-claude-code-plugins-marketplace">
 <h1>Mapping to Claude Code Plugins Marketplace</h1>
 <p>This appendix describes how the Anthropic Claude Code Plugins
@@ -2031,7 +2239,7 @@
 maps to AI Catalog, enabling Claude Code plugins to be discovered,
 indexed, and distributed through a unified catalog alongside other AI
 artifacts.</p>
-<section id="overview-2">
+<section id="overview-3">
 <h2>Overview</h2>
 <p>The Claude Code Plugins marketplace is defined by a <code>marketplace.json</code>
 file that lists available plugins. Each plugin is a directory containing
@@ -2050,7 +2258,7 @@
     README.md
 </code></pre>
 </section>
-<section id="conceptual-mapping-3">
+<section id="conceptual-mapping-4">
 <h2>Conceptual Mapping</h2>
 <table>
 <thead>
