diff --git a/.claude-plugin/marketplace.json b/.claude-plugin/marketplace.json
index 719473def..4dc2f3260 100644
--- a/.claude-plugin/marketplace.json
+++ b/.claude-plugin/marketplace.json
@@ -11,7 +11,7 @@
   "plugins": [
     {
       "name": "gitnexus",
-      "version": "1.3.3",
+      "version": "1.6.6",
       "source": "./gitnexus-claude-plugin",
       "description": "Code intelligence powered by a knowledge graph. Provides execution flow tracing, blast radius analysis, and augmented search across your codebase."
     }
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index ddefad384..848884be4 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -157,7 +157,12 @@ routes between two modes based on the triggering event:
   suffix; RC tags are excluded at trigger via a negative glob). Publishes to
   the `latest` dist-tag with a changelog-backed GitHub release. Maintainers
   are expected to tag from `main` as a convention; the workflow itself does
-  not enforce branch reachability. No Docker build (RC-only).
+  not enforce branch reachability. No Docker build (RC-only). Before cutting a
+  stable release, keep `gitnexus/package.json`,
+  `gitnexus-claude-plugin/.claude-plugin/plugin.json`,
+  `.claude-plugin/marketplace.json`, and the matching `CHANGELOG.md` entry in
+  lockstep — the always-on `gitnexus` unit suite now fails if those manifest
+  versions drift.
 - **Release-candidate mode** — runs on every push to `main` (typically a
   merged PR) plus manual `workflow_dispatch`. Docs-only changes are skipped
   via `paths-ignore`. Publishes to the `rc` dist-tag with version
diff --git a/gitnexus-claude-plugin/.claude-plugin/plugin.json b/gitnexus-claude-plugin/.claude-plugin/plugin.json
index bd4b8c426..da6b42a7b 100644
--- a/gitnexus-claude-plugin/.claude-plugin/plugin.json
+++ b/gitnexus-claude-plugin/.claude-plugin/plugin.json
@@ -1,7 +1,7 @@
 {
   "name": "gitnexus",
   "description": "Code intelligence powered by a knowledge graph. Provides execution flow tracing, blast radius analysis, and augmented search across your codebase.",
-  "version": "1.3.6",
+  "version": "1.6.6",
   "author": {
     "name": "GitNexus"
   },
diff --git a/gitnexus/test/unit/cli-commands.test.ts b/gitnexus/test/unit/cli-commands.test.ts
index 26b0b6f66..fcae5d0bd 100644
--- a/gitnexus/test/unit/cli-commands.test.ts
+++ b/gitnexus/test/unit/cli-commands.test.ts
@@ -1,5 +1,14 @@
+import fs from 'node:fs/promises';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
 import { describe, it, expect, vi } from 'vitest';
 
+const REPO_ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..', '..', '..');
+
+async function readRepoJson<T>(relativePath: string): Promise<T> {
+  return JSON.parse(await fs.readFile(path.join(REPO_ROOT, relativePath), 'utf8')) as T;
+}
+
 // Mock all the heavy imports before importing index
 vi.mock('../../src/cli/analyze.js', () => ({
   analyzeCommand: vi.fn(),
@@ -20,6 +29,26 @@ describe('CLI commands', () => {
       const pkg = await import('../../package.json', { with: { type: 'json' } });
       expect(pkg.default.version).toMatch(/^\d+\.\d+\.\d+/);
     });
+
+    it('keeps Claude plugin manifests aligned with the gitnexus release version', async () => {
+      const pkg = await import('../../package.json', { with: { type: 'json' } });
+      const pluginManifest = await readRepoJson<{ version: string }>(
+        'gitnexus-claude-plugin/.claude-plugin/plugin.json',
+      );
+      const marketplaceManifest = await readRepoJson<{
+        plugins?: Array<{ name: string; version: string }>;
+      }>('.claude-plugin/marketplace.json');
+
+      expect(Array.isArray(marketplaceManifest.plugins)).toBe(true);
+
+      const gitnexusEntries = (marketplaceManifest.plugins ?? []).filter(
+        (plugin) => plugin.name === 'gitnexus',
+      );
+
+      expect(gitnexusEntries).toHaveLength(1);
+      expect(pluginManifest.version).toBe(pkg.default.version);
+      expect(gitnexusEntries[0]?.version).toBe(pkg.default.version);
+    });
   });
 
   describe('package.json scripts', () => {