diff --git a/AGENTS.md b/AGENTS.md
index 69651022d..eb0587e68 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -43,6 +43,7 @@ Invoke them by name (e.g., `/office-hours`).
 
 | Skill | What it does |
 |-------|-------------|
+| `/pr-prep` | Pre-PR upstream duplicate audit. Scores each commit against upstream issues + PRs; blocks on exact duplicates. Hooks into `/ship` as Step 0. |
 | `/ship` | Run tests, review, push, open PR. Workspace-aware version queue. |
 | `/land-and-deploy` | Merge the PR, wait for CI and deploy, verify production health. |
 | `/canary` | Post-deploy monitoring loop using the browse daemon. |
diff --git a/docs/skills.md b/docs/skills.md
index 8e8cb7adc..5fa5a561a 100644
--- a/docs/skills.md
+++ b/docs/skills.md
@@ -19,6 +19,7 @@ Detailed guides for every gstack skill — philosophy, workflow, and examples.
 | [`/qa-only`](#qa) | **QA Reporter** | Same methodology as /qa but report only. Use when you want a pure bug report without code changes. |
 | [`/scrape`](#scrape) | **Browser Data Extractor** | Pull data from a web page. First call prototypes via `$B`; subsequent calls on a matching intent run a codified browser-skill in ~200ms. |
 | [`/skillify`](#skillify) | **Skill Codifier** | Walks back through your conversation, finds the last `/scrape` prototype, synthesizes script + test + fixture, runs the test, asks before committing. |
+| [`/pr-prep`](#pr-prep) | **PR Auditor** | Pre-PR upstream duplicate audit. Walks `git log base..HEAD`, queries upstream issues + PRs, scores each commit (EXACT_DUP / OVERLAP / SIBLING / CLEAN), and refuses to proceed on exact duplicates. Hooks into `/ship` as Step 0. |
 | [`/ship`](#ship) | **Release Engineer** | Sync main, run tests, audit coverage, push, open PR. Bootstraps test frameworks if you don't have one. One command. |
 | [`/land-and-deploy`](#land-and-deploy) | **Release Engineer** | Merge the PR, wait for CI and deploy, verify production health. One command from "approved" to "verified in production." |
 | [`/canary`](#canary) | **SRE** | Post-deploy monitoring loop. Watches for console errors, performance regressions, and page failures using the browse daemon. |