Run sync when issue is labeled with Sync Backport Changelog

.github/workflows/sync-backport-changelog.yml

@@ -4,20 +4,36 @@ on:
     push:
         branches:
             - trunk
+    issues:
+        types: [labeled]
 
 jobs:
     sync-backport-changelog:
         name: Sync Core Backport Issue
         runs-on: ubuntu-latest
+        if: >
+            github.event_name == 'push' ||
+            (
+                github.event_name == 'issues' &&
+                github.event.action == 'labeled' &&
+                github.event.label.name == '🤖 Sync Backport Changelog'
+            )
         steps:
             - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
               with:
                   fetch-depth: 2 # Fetch the last two commits to compare changes
             - name: Check for changes in backport-changelog
+              id: check-for-changes
               run: |
-                  git diff --quiet HEAD^ HEAD -- backport-changelog || echo "changes=true" >> $GITHUB_OUTPUT
+                  git diff --quiet HEAD^ HEAD -- backport-changelog || echo "HAS_CHANGES=1" >> "$GITHUB_OUTPUT"
             - name: Sync Issue
-              if: env.changes == 'true'
+              if: >
+                  steps.check-for-changes.outputs.HAS_CHANGES ||
+                  (
+                      github.event_name == 'issues' &&
+                      github.event.action == 'labeled' &&
+                      github.event.label.name == '🤖 Sync Backport Changelog'
+                  )
               uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7.0.1
               with:
                   script: |
@@ -52,18 +68,20 @@ jobs:
                       const endDelimiter = '<!-- END TRUNK BACKPORT CHANGELOG -->';
                       const autoGeneratedContent = `${startDelimiter}\n${processedChangelog}\n${endDelimiter}`;
 
-                      const regex = new RegExp(`${startDelimiter}[\\s\\S]*${endDelimiter}`);
+                      const existingBody = latestIssue.body ?? '';
+
                       let newBody;
 
-                      if (regex.test(latestIssue.body)) {
+                      const regex = new RegExp(`${startDelimiter}[\\s\\S]*${endDelimiter}`);
+                      if (regex.test(existingBody)) {
                         // If delimiters exist, replace the content between them
-                        newBody = latestIssue.body.replace(regex, autoGeneratedContent);
+                        newBody = existingBody.replace(regex, autoGeneratedContent);
                       } else {
                         // If delimiters don't exist, append the new content at the end
-                        newBody = `${latestIssue.body}\n\n${autoGeneratedContent}`;
+                        newBody = `${existingBody}\n\n${autoGeneratedContent}`;
                       }
 
-                      if (newBody.trim() !== latestIssue.body.trim()) {
+                      if (newBody.trim() !== existingBody.trim()) {
                         await github.rest.issues.update({
                           owner: context.repo.owner,
                           repo: context.repo.repo,