diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 9b033155..f08c85ee 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -12,8 +12,9 @@ This pack already covers most of the development lifecycle, and many proposals o
 
 1. **Search the catalog.** Browse [the skill list in the README](README.md) and skim `skills/` for an existing skill that covers your idea, whole or in part.
 2. **Check open PRs.** Run `gh pr list --state open` (or browse the PRs tab) and look for proposals on the same topic. Clusters of near-duplicate skills already exist; don't add to them.
-3. **Read the anatomy.** Confirm your idea fits the format in [docs/skill-anatomy.md](docs/skill-anatomy.md), an actionable workflow with verification, not vague advice.
-4. **Justify the gap in your PR description.** State explicitly why this isn't covered by an existing skill or open PR. If it overlaps, propose extending the existing skill instead of adding a new one.
+3. **Check rejected proposals.** Search the [skill-change rejection ledger](evals/skill-impact.md) for earlier proposals that overlap with your idea and review their eval evidence before repeating the work.
+4. **Read the anatomy.** Confirm your idea fits the format in [docs/skill-anatomy.md](docs/skill-anatomy.md), an actionable workflow with verification, not vague advice.
+5. **Justify the gap in your PR description.** State explicitly why this isn't covered by an existing skill, open PR, or previously rejected proposal. If it overlaps, propose extending the existing skill instead of adding a new one.
 
 If your idea is a refinement of an existing skill, prefer a focused edit to that skill over a new directory.
 
@@ -62,10 +63,14 @@ The frontmatter fields above are required. The section anatomy is a recommended
 
 ## Modifying Existing Skills
 
+Before proposing a change, search the [skill-change rejection ledger](evals/skill-impact.md) for previous attempts affecting the same skill and review their eval evidence.
+
 - Keep changes focused and minimal
 - Preserve the existing structure and tone
 - Test that YAML frontmatter remains valid after edits
 
+If a skill or description change is rejected based on eval results, add one row to the ledger with the date, affected skill, concise attempted change, before-to-after rank-1 score, and rejected PR link and outcome. Land that ledger-only update separately on the default branch; do not leave it only on the rejected proposal branch, where closing or force-pushing the proposal could discard the record.
+
 ## Repo-scoped files
 
 `AGENTS.md` and `CLAUDE.md` at the repo root configure agents working on the [`addyosmani/agent-skills`](https://github.com/addyosmani/agent-skills) repository itself. When writing setup guides or docs, do not instruct users to copy these files into their own projects or into a global agent configuration; the reusable assets are the skills in `skills/`.
diff --git a/evals/skill-impact.md b/evals/skill-impact.md
new file mode 100644
index 00000000..a40ef136
--- /dev/null
+++ b/evals/skill-impact.md
@@ -0,0 +1,6 @@
+# Rejected Skill Changes
+
+This append-only ledger records skill and description changes rejected on eval evidence so contributors can review prior attempts before proposing overlapping work. Add one concise row per rejected proposal; do not record accepted changes here.
+
+| Date | Affected skill | Attempted change | Rank-1 score (before → after) | Rejected PR and outcome |
+|---|---|---|---:|---|