chore: distinguish backport pull requests by title and label (#32381)

.github/workflows/claude-issue-agent.yml

@@ -30,8 +30,12 @@ jobs:
   pr-label:
     name: PR labeling
     # bot PRs (dependabot etc.) are skipped: the action rejects non-human actors
-    # unless allowlisted, and bots already label their own PRs
-    if: github.event_name == 'pull_request_target' && github.event.pull_request.user.type != 'Bot'
+    # unless allowlisted, and bots already label their own PRs. backports are
+    # skipped as well, they carry the backport label and nothing else
+    if: |
+      github.event_name == 'pull_request_target' &&
+      github.event.pull_request.user.type != 'Bot' &&
+      !startsWith(github.event.pull_request.head.ref, 'backport/')
     runs-on: ubuntu-latest
     permissions:
       contents: read # read base repo for area classification

.github/workflows/command-backport.yml

@@ -158,11 +158,15 @@ jobs:
           NUMBER: ${{ github.event.issue.number }}
           ACTOR: ${{ github.event.comment.user.login }}
         run: |
+          # the release line the branch was cut from, 0.313 for release/0.313.1
+          line=$(echo "${TARGET#release/}" | cut -d. -f1,2)
+
           # the pull request is authored by the deploy token, so name the requester
           url=$(gh pr create \
             --base "$TARGET" \
             --head "$BRANCH" \
-            --title "$TITLE" \
+            --title "$line backport: $TITLE" \
+            --label backport \
             --assignee "$ACTOR" \
             --body "Backport of #$NUMBER to \`$TARGET\`, requested by @$ACTOR.")
           echo "url=$url" >> "$GITHUB_OUTPUT"