diff --git a/.github/workflows/retrigger-prb-on-ready.yml b/.github/workflows/retrigger-prb-on-ready.yml
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+name: Retrigger PRB on ready for review
+
+# When a draft PR is marked ready_for_review, GitHub fires a
+# 'ready_for_review' pull_request event but no 'synchronize' event, so
+# the Jenkins GHPRB plugin does not re-trigger the PRB-master-job. Post
+# the configured GHPRB trigger phrase as a PR comment to kick it off.
+#
+# pull_request_target (not pull_request) is required so GITHUB_TOKEN
+# gets write permissions on PRs from forks - this workflow only posts
+# a fixed comment string, so the usual pull_request_target risk
+# (executing untrusted PR code with elevated privileges) does not apply.
+
+on:
+  pull_request_target:
+    types: [ready_for_review]
+    branches: [master, main]
+
+permissions:
+  pull-requests: write
+
+jobs:
+  retrigger:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Post GHPRB trigger comment
+        uses: actions/github-script@v7
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            await github.rest.issues.createComment({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: 'retest this please'
+            })