diff --git a/.claude-plugin/marketplace.json b/.claude-plugin/marketplace.json
new file mode 100644
index 0000000000..f44b5f3c24
--- /dev/null
+++ b/.claude-plugin/marketplace.json
@@ -0,0 +1,15 @@
+{
+  "name": "codebase-memory",
+  "description": "The codebase-memory-mcp code knowledge graph server, as a Claude Code plugin.",
+  "owner": {
+    "name": "DeusData",
+    "url": "https://github.com/DeusData"
+  },
+  "plugins": [
+    {
+      "name": "codebase-memory",
+      "source": "./plugin",
+      "description": "Codebase knowledge graph for AI agents: sub-ms queries, 99% fewer tokens."
+    }
+  ]
+}
diff --git a/.gitignore b/.gitignore
index 1533c93e00..c388fa360f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -33,6 +33,8 @@ Thumbs.db
 
 # MCP config (user-local, generated by install command)
 .mcp.json
+# ...except the Claude Code plugin's server definition, which is published
+!plugin/.mcp.json
 
 # MCP Registry auth tokens
 .mcpregistry_*
diff --git a/README.md b/README.md
index 1a83289eed..9b1ef59053 100644
--- a/README.md
+++ b/README.md
@@ -578,6 +578,30 @@ Working in a clone? Use `.` in place of the flake URL, e.g. `nix run .#codebase-
 You: "Install this MCP server: https://github.com/DeusData/codebase-memory-mcp"
 ```
 
+### Install via Claude Code plugin
+
+This repository is also a Claude Code plugin marketplace, so you can find and
+add the server from inside Claude Code:
+
+```bash
+claude plugin marketplace add DeusData/codebase-memory-mcp
+claude plugin install codebase-memory@codebase-memory
+```
+
+The plugin registers the MCP server only. It starts the server with
+`npx -y codebase-memory-mcp@<version>`, pinned to the current release; the first
+start downloads that release's binary through the npm package, which verifies
+it against the release checksums. The skill, the three graph agents and the
+context hooks are not part of the plugin: they come from
+`codebase-memory-mcp install`.
+
+Use one or the other. `install` registers the same server for Claude Code, so
+with both you run it twice, under two tool namespaces
+(`mcp__codebase-memory-mcp__*` and
+`mcp__plugin_codebase-memory_codebase-memory-mcp__*`). Choose `install` for the
+full Claude Code setup; choose the plugin to add just the server without
+running an installer.
+
 ### Build from Source
 
 <details>
diff --git a/plugin/.claude-plugin/plugin.json b/plugin/.claude-plugin/plugin.json
new file mode 100644
index 0000000000..0960a2b718
--- /dev/null
+++ b/plugin/.claude-plugin/plugin.json
@@ -0,0 +1,9 @@
+{
+  "name": "codebase-memory",
+  "version": "0.12.1",
+  "description": "Codebase knowledge graph for AI agents: sub-ms queries, 99% fewer tokens.",
+  "author": {
+    "name": "DeusData",
+    "url": "https://github.com/DeusData"
+  }
+}
diff --git a/plugin/.mcp.json b/plugin/.mcp.json
new file mode 100644
index 0000000000..07fbe13c1e
--- /dev/null
+++ b/plugin/.mcp.json
@@ -0,0 +1,9 @@
+{
+  "mcpServers": {
+    "codebase-memory-mcp": {
+      "type": "stdio",
+      "command": "npx",
+      "args": ["-y", "codebase-memory-mcp@0.12.1"]
+    }
+  }
+}
diff --git a/tests/test_version_metadata_contract.sh b/tests/test_version_metadata_contract.sh
index b74203bf6b..54d7879442 100644
--- a/tests/test_version_metadata_contract.sh
+++ b/tests/test_version_metadata_contract.sh
@@ -109,6 +109,8 @@ SURFACES=(
     "pkg/chocolatey/tools/chocolateyInstall.ps1|release"
     "pkg/scoop/codebase-memory-mcp.json|release"
     "pkg/homebrew/Formula/codebase-memory-mcp.rb|release"
+    "plugin/.claude-plugin/plugin.json|release"
+    "plugin/.mcp.json|release"
     "pkg/aur/PKGBUILD|pin:0.8.1"
     "pkg/aur/.SRCINFO|pin:0.8.1"
 )
@@ -163,6 +165,12 @@ versions_in() {
         # cannot see it, because the version keyword is in the function NAME.
         grep -oE 'return "[0-9]+\.[0-9]+\.[0-9]+"' "$path" |
             grep -oE '[0-9]+\.[0-9]+\.[0-9]+'
+        # npm package-spec form: the Claude Code plugin launches the server as
+        # `npx -y codebase-memory-mcp@X.Y.Z`, and that pin is the version every
+        # plugin user actually runs. No declaration keyword sits next to it, so
+        # without this form plugin/.mcp.json reads as a surface with no claim.
+        grep -oE 'codebase-memory-mcp@[0-9]+\.[0-9]+\.[0-9]+' "$path" |
+            grep -oE '[0-9]+\.[0-9]+\.[0-9]+$'
     } | sort -u
 }
 
@@ -280,7 +288,9 @@ fi
 # this contract exists to prevent, and every check above would still pass. The
 # sweep pattern is deliberately BROADER than the extractors in section 3: if the
 # two shared a regex, a claim form the extractors cannot see would be invisible
-# to the sweep as well.
+# to the sweep as well. The Claude Code plugin tree (plugin/, .claude-plugin/) is
+# swept too: a later plugin file that pins `codebase-memory-mcp@X.Y.Z` (a hook
+# command, say) must be registered here, or it would go stale unchecked.
 while IFS= read -r path; do
     [[ -z "$path" ]] && continue
     for entry in "${SURFACES[@]}"; do
@@ -293,8 +303,8 @@ while IFS= read -r path; do
         "SURFACES so it stays in step with the release, or to EXEMPT with a" \
         "note saying what its number actually is."
 done < <(
-    git grep -IlE '(version|pkgver|releases/(download|tag)/v)[^0-9]{0,16}[0-9]+\.[0-9]+\.[0-9]+|return "[0-9]+\.[0-9]+\.[0-9]+"' \
-        -- server.json pkg tests/test_version_metadata_contract.sh 2>/dev/null || true
+    git grep -IlE '(version|pkgver|releases/(download|tag)/v)[^0-9]{0,16}[0-9]+\.[0-9]+\.[0-9]+|return "[0-9]+\.[0-9]+\.[0-9]+"|codebase-memory-mcp@[0-9]+\.[0-9]+\.[0-9]+' \
+        -- server.json pkg plugin .claude-plugin tests/test_version_metadata_contract.sh 2>/dev/null || true
 )
 
 if ((failures > 0)); then