ci: comment on stale dist bundles

Signed-off-by: Rui Chen <[email protected]>

Author: chenrui333

.github/workflows/main.yml

@@ -4,6 +4,11 @@ on:
   push:
   pull_request:
 
+permissions:
+  contents: read
+  issues: write
+  pull-requests: write
+
 jobs:
   build:
     runs-on: ubuntu-24.04
@@ -20,10 +25,49 @@ jobs:
       - name: Build
         run: npm run build
       - name: Check dist freshness
+        id: dist_freshness
+        continue-on-error: true
         run: |
           git diff --exit-code --stat -- dist/index.js \
           || (echo "##[error] found changed dist/index.js after build. please run 'npm run build' and commit the updated bundle" \
               && exit 1)
+      - name: Comment on stale dist bundle
+        if: github.event_name == 'pull_request' && steps.dist_freshness.outcome == 'failure'
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GH_REPO: ${{ github.repository }}
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+        run: |
+          marker='<!-- dist-freshness-check -->'
+          diff_stat="$(git diff --stat -- dist/index.js)"
+          body=$(cat <<EOF
+          $marker
+          \`dist/index.js\` changed after \`npm run build\`.
+
+          Please run \`npm run build\` and commit the regenerated bundle.
+
+          \`\`\`text
+          $diff_stat
+          \`\`\`
+          EOF
+          )
+
+          existing_id="$(
+            gh api "repos/$GH_REPO/issues/$PR_NUMBER/comments" \
+              --jq '.[] | select(.user.login == "github-actions[bot]" and (.body | contains("<!-- dist-freshness-check -->"))) | .id' \
+              | tail -n 1
+          )"
+
+          if [ -n "$existing_id" ]; then
+            gh api --method PATCH "repos/$GH_REPO/issues/comments/$existing_id" -f body="$body" >/dev/null
+          else
+            gh api --method POST "repos/$GH_REPO/issues/$PR_NUMBER/comments" -f body="$body" >/dev/null
+          fi
+      - name: Fail on stale dist bundle
+        if: steps.dist_freshness.outcome == 'failure'
+        run: |
+          echo "##[error] found changed dist/index.js after build. please run 'npm run build' and commit the updated bundle"
+          exit 1
       - name: Test
         run: npm run test
       - name: Format