diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 5b057b0..b503eff 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -29,7 +29,7 @@ jobs:
       - name: Create Version Pull Request
         uses: changesets/action@v1
         with:
-          version: npx changeset version
+          version: npm run version
           publish: npx changeset tag
           commit: "chore: version skills"
           title: "chore: version skills"
diff --git a/CLAUDE.md b/CLAUDE.md
index 2dfb777..8b87834 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -8,7 +8,7 @@ Skills are organized into bucket folders under `skills/`:
 
 Every skill in `engineering/` or `productivity/` (the **promoted** buckets) must have a reference in the top-level `README.md` and an entry in `.claude-plugin/plugin.json`'s `skills` array (the Claude Code plugin ships exactly the promoted set). Skills in `misc/`, `in-progress/`, and `deprecated/` must not appear in either.
 
-Install commands are copied verbatim from [.agents/install-block.md](./.agents/install-block.md). `.claude-plugin/marketplace.json` makes the repo its own single-plugin marketplace — a fallback the install block explains, not the documented route. When bumping the release version, keep `.claude-plugin/plugin.json`'s `version` in sync with `package.json`'s — Claude uses the plugin `version` to decide when installed users see an update. Run `claude plugin validate . --strict` after touching either manifest. Why a Claude plugin but not (yet) a Codex one lives in [.agents/adr/0002-ship-as-a-claude-code-plugin.md](./.agents/adr/0002-ship-as-a-claude-code-plugin.md).
+Install commands are copied verbatim from [.agents/install-block.md](./.agents/install-block.md). `.claude-plugin/marketplace.json` makes the repo its own single-plugin marketplace — a fallback the install block explains, not the documented route. Run `claude plugin validate . --strict` after touching either manifest. Why a Claude plugin but not (yet) a Codex one lives in [.agents/adr/0002-ship-as-a-claude-code-plugin.md](./.agents/adr/0002-ship-as-a-claude-code-plugin.md).
 
 Each skill entry in the top-level `README.md` must link the skill name to its `SKILL.md`.
 
diff --git a/package.json b/package.json
index 6e870b8..c03fe7a 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "mattpocock-skills",
-  "version": "1.2.0",
+  "version": "1.2.1",
   "private": true,
   "description": "Matt Pocock's agent skills for real engineering",
   "repository": {
@@ -10,7 +10,8 @@
   "license": "MIT",
   "scripts": {
     "changeset": "changeset",
-    "version": "changeset version"
+    "version": "changeset version && node scripts/sync-plugin-version.mjs",
+    "check-plugin-version": "node scripts/sync-plugin-version.mjs --check"
   },
   "devDependencies": {
     "@changesets/changelog-github": "^0.7.0",
diff --git a/scripts/sync-plugin-version.mjs b/scripts/sync-plugin-version.mjs
new file mode 100644
index 0000000..c9e9907
--- /dev/null
+++ b/scripts/sync-plugin-version.mjs
@@ -0,0 +1,41 @@
+#!/usr/bin/env node
+// Copies package.json's version into .claude-plugin/plugin.json.
+// Runs as part of `npm run version`, immediately after `changeset version`.
+// With --check it changes nothing and exits 1 if the two versions differ.
+
+import { readFileSync, writeFileSync } from "node:fs";
+import { dirname, join } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const repo = join(dirname(fileURLToPath(import.meta.url)), "..");
+const pluginPath = join(repo, ".claude-plugin", "plugin.json");
+
+const { version } = JSON.parse(readFileSync(join(repo, "package.json"), "utf8"));
+const source = readFileSync(pluginPath, "utf8");
+const plugin = JSON.parse(source);
+
+if (plugin.version === version) {
+  console.log(`plugin.json version is ${version} — already in sync`);
+  process.exit(0);
+}
+
+if (process.argv.includes("--check")) {
+  console.error(
+    `plugin.json version is ${plugin.version}, package.json is ${version}. Run \`node scripts/sync-plugin-version.mjs\`.`,
+  );
+  process.exit(1);
+}
+
+// Rewrite only the version line, to keep the key order and the formatting.
+const updated = source.replace(
+  /("version"\s*:\s*")[^"]*(")/,
+  `$1${version}$2`,
+);
+
+if (JSON.parse(updated).version !== version) {
+  console.error(`Could not find a version field to replace in ${pluginPath}.`);
+  process.exit(1);
+}
+
+writeFileSync(pluginPath, updated);
+console.log(`plugin.json version ${plugin.version} -> ${version}`);