ci: restrict npm publish tags to main

.github/workflows/npm-publish.yml

@@ -15,6 +15,15 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Verify tag is on main
+        run: |
+          git merge-base --is-ancestor "$GITHUB_SHA" origin/main || {
+            echo "Tag $GITHUB_REF_NAME ($GITHUB_SHA) is not on main; refusing to publish."
+            exit 1
+          }
 
       - name: Setup Node.js
         uses: actions/setup-node@v4

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### CI
+
+- Restrict npm publishing to tags whose commit is already on `main`.
+
 ## [0.2.5] - 2026-07-14
 
 ### Changed