diff --git a/.github/workflows/enforce-pr-source.yml b/.github/workflows/enforce-pr-source.yml
new file mode 100644
index 00000000..eec6cf73
--- /dev/null
+++ b/.github/workflows/enforce-pr-source.yml
@@ -0,0 +1,19 @@
+name: Enforce PR Source
+
+on:
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  check-pr-source:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Enforce only staging → main
+        run: |
+          echo "head_ref: ${{ github.head_ref }}"
+          echo "base_ref: ${{ github.base_ref }}"
+          if [[ "${{ github.head_ref }}" != "staging" ]]; then
+            echo "ERROR: Only 'staging' branch may create PRs into 'main'!"
+            exit 1
+          fi