diff --git a/.github/workflows/on-child-update.yml b/.github/workflows/on-child-update.yml
new file mode 100644
index 0000000..679d2c6
--- /dev/null
+++ b/.github/workflows/on-child-update.yml
@@ -0,0 +1,83 @@
+name: On Child Repo Update
+
+on:
+  repository_dispatch:
+    types: [child-repo-updated]
+
+concurrency:
+  group: child-repo-sync
+  cancel-in-progress: false
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  create-sync-pr:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          token: ${{ secrets.PARENT_REPO_PAT }}
+
+      - name: Create sync PR
+        env:
+          REPO_NAME: ${{ github.event.client_payload.repo_name }}
+          FULL_SHA: ${{ github.event.client_payload.sha }}
+          GH_TOKEN: ${{ secrets.PARENT_REPO_PAT }}
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+
+          REPO_NAME="${REPO_NAME:-unknown}"
+          SHORT_SHA="${FULL_SHA:0:7}"
+          SHORT_SHA="${SHORT_SHA:-$(date +%s | tail -c 8)}"
+
+          BRANCH="sync/${REPO_NAME}/${SHORT_SHA}"
+          PR_TITLE="chore(${REPO_NAME}): sync ${SHORT_SHA}"
+
+          # Check for existing branch
+          if git ls-remote --exit-code origin "refs/heads/$BRANCH" >/dev/null 2>&1; then
+            EXISTING_PR=$(gh pr list --head "$BRANCH" --base main --json url --jq '.[0].url // empty')
+            if [[ -n "$EXISTING_PR" ]]; then
+              echo "PR already exists: $EXISTING_PR"
+              gh pr merge "$EXISTING_PR" --auto --squash --delete-branch || true
+              exit 0
+            fi
+            # Branch exists but no PR — previous run pushed but failed to create PR.
+            # Delete the orphaned branch and recreate cleanly.
+            echo "Found orphaned branch $BRANCH (no PR) — deleting and recreating"
+            delete_output=$(git push origin --delete "$BRANCH" 2>&1) || {
+              if git ls-remote --exit-code origin "refs/heads/$BRANCH" >/dev/null 2>&1; then
+                echo "Failed to delete orphaned branch: $delete_output"
+                exit 1
+              fi
+            }
+          fi
+
+          git checkout -b "$BRANCH"
+          git commit --allow-empty -m "$PR_TITLE"
+
+          push_output=$(git push -u origin "$BRANCH" 2>&1) || {
+            if echo "$push_output" | grep -qE "(non-fast-forward|already exists|fetch first)"; then
+              echo "Push failed due to race condition — another run likely handled this"
+              exit 0
+            fi
+            echo "Push failed unexpectedly: $push_output"
+            exit 1
+          }
+
+          PR_URL=$(gh pr create \
+            --title "$PR_TITLE" \
+            --body "Synced from \`${REPO_NAME}@${SHORT_SHA}\`" \
+            --head "$BRANCH" \
+            --base main) || {
+            echo "PR creation failed — deleting orphaned branch"
+            git push origin --delete "$BRANCH" || true
+            exit 1
+          }
+
+          gh pr merge "$PR_URL" --auto --squash --delete-branch || true
+          echo "PR ready: $PR_URL"
+