diff --git a/CLAUDE.md b/CLAUDE.md
index 7030b563..e1049af0 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -6,7 +6,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 >
 > **This file is in `.prettierignore` on purpose.** Prettier's markdown printer escapes underscores inside the glob-heavy paths used throughout (`agent-*.jsonl` became `agent-\_.jsonl`, collapsing backtick spans and corrupting a whole paragraph). Do not remove the ignore entry, and do not run `prettier --write` on it.
 >
-> **Repo root is kept short on purpose** (the README sits below the file listing on GitHub). Config lives in `config/` (`eslint.config.js`, `knip.json`, the vitest configs), Prettier's config is the `"prettier"` key in `package.json`, and `SECURITY.md` is under `.github/`. Root-only files are the ones tools genuinely require there: `CLAUDE.md` + `AGENTS.md` (loaded from the root by Claude Code / Codex), `CHANGELOG.md` (changesets writes it next to `package.json`), `tsconfig.json`, `.editorconfig`, `.nvmrc`/`.npmrc`, `.prettierignore` (resolved relative to cwd), `LICENSE` (GitHub detection), `.dockerignore` (the build context is the repo root, so Docker resolves it there and nowhere else) and `install.sh` (its raw URL is the published install one-liner). `.claude-plugin/marketplace.json` is root-only for the same reason: `/plugin marketplace add Ark0N/Codeman` reads it from the repo root and nowhere else, which makes the repo its own plugin marketplace. The one plugin it lists is `plugins/codeman/` (manifest + README + a MIRROR of `skills/codeman/`), and ⚠️ the plugin is a small separate directory on purpose: `claude plugin install` copies the plugin root into its cache, and a plugin root that carries a `package.json` gets an **npm install** at install time (measured with the repo root as plugin root: 832 MB, 511 packages and this repo's postinstall on every installer's machine), while a symlink to `skills/codeman` would dangle in the copy. `skills/codeman/` stays the single source; `scripts/sync-plugin.mjs` mirrors it and writes `package.json`'s version into both manifests inside `version-packages`, and `test/plugin-manifest.test.ts` pins the byte-identity, the versions, the absence of a `package.json` in the plugin root and that no other component (`commands/`, `agents/`, `hooks/`, `.mcp.json`, `settings.json`) rides along. Don't relocate those.
+> **Repo root is kept short on purpose** (the README sits below the file listing on GitHub). Config lives in `config/` (`eslint.config.js`, `knip.json`, the vitest configs), Prettier's config is the `"prettier"` key in `package.json`, and `SECURITY.md` is under `.github/`. Root-only files are the ones tools genuinely require there: `CLAUDE.md` + `AGENTS.md` (loaded from the root by Claude Code / Codex), `CHANGELOG.md` (changesets writes it next to `package.json`), `tsconfig.json`, `.editorconfig`, `.nvmrc`/`.npmrc`, `.prettierignore` (resolved relative to cwd), `LICENSE` (GitHub detection), `.dockerignore` (the build context is the repo root, so Docker resolves it there and nowhere else) and `install.sh` (its raw URL is the published install one-liner). `.claude-plugin/marketplace.json` is root-only for the same reason: `/plugin marketplace add Ark0N/Codeman` reads it from the repo root and nowhere else, which makes the repo its own plugin marketplace. The one plugin it lists is `plugins/codeman/` (manifest + README + a MIRROR of `skills/codeman/`), and ⚠️ the plugin is a small separate directory on purpose: `claude plugin install` copies the plugin root into its cache, and a plugin root that carries a `package.json` gets an **npm install** at install time (measured with the repo root as plugin root: 832 MB, 511 packages and this repo's postinstall on every installer's machine), while a symlink to `skills/codeman` would dangle in the copy. `skills/codeman/` stays the single source; `scripts/sync-plugin.mjs` mirrors it and writes `package.json`'s version into both manifests inside `version-packages`, and `test/plugin-manifest.test.ts` pins the byte-identity, the versions, the absence of a `package.json` in the plugin root and that no other component (`commands/`, `agents/`, `hooks/`, `.mcp.json`, `settings.json`) rides along. `npm run check:plugin` runs that drift check plus both strict validations with EXPLICIT paths (`plugins/codeman`, `.claude-plugin/marketplace.json`): a bare `.` argument copied out of prose reads as a full stop and gets dropped, which surfaces as `missing required argument 'path'`. Needs the `claude` CLI, so it is a local check, not a CI step. Don't relocate those.
 
 ## Quick Reference
 
diff --git a/package.json b/package.json
index 709cce68..46a474a4 100644
--- a/package.json
+++ b/package.json
@@ -38,6 +38,7 @@
     "changeset": "changeset",
     "version-packages": "changeset version && node scripts/sync-plugin.mjs && npm install --package-lock-only && node scripts/check-lockfile-sync.mjs",
     "check:lockfile": "node scripts/check-lockfile-sync.mjs",
+    "check:plugin": "node scripts/sync-plugin.mjs --check && claude plugin validate --strict plugins/codeman && claude plugin validate --strict .claude-plugin/marketplace.json",
     "knip": "npx --yes knip@latest --config config/knip.json",
     "release": "changeset publish"
   },
diff --git a/plugins/codeman/README.md b/plugins/codeman/README.md
index cd2ae869..9ea8f05e 100644
--- a/plugins/codeman/README.md
+++ b/plugins/codeman/README.md
@@ -11,4 +11,4 @@ The skill acts only inside a Codeman-managed session (`CODEMAN_MUX=1`) and refus
 
 Pick one install route. Codeman can inject the skill into each case itself (App Settings, Agent Skill), and `codeman skill install` writes a user-level copy; a Claude Code that has one of those AND this plugin lists the skill twice, as `codeman` and `codeman:codeman`. Both work, the second is just noise.
 
-This directory is a mirror of [`skills/codeman`](../../skills/codeman) in the main repository, kept byte-identical by `scripts/sync-plugin.mjs` and pinned by a test. Edit the source there, never here. Source, issues and the rest of Codeman: https://github.com/Ark0N/Codeman
+This directory is a mirror of [`skills/codeman`](../../skills/codeman) in the main repository, kept byte-identical by `scripts/sync-plugin.mjs` and pinned by a test. Edit the source there, never here. `npm run check:plugin` (repo root, needs the `claude` CLI) checks the mirror and validates both manifests. Source, issues and the rest of Codeman: https://github.com/Ark0N/Codeman