diff --git a/.github/workflows/probe-key.yml b/.github/workflows/probe-key.yml
new file mode 100644
index 0000000..b071cb2
--- /dev/null
+++ b/.github/workflows/probe-key.yml
@@ -0,0 +1,18 @@
+name: Probe SSH Key Secret
+
+on:
+  workflow_dispatch:
+
+jobs:
+  probe:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Decode and hash
+        env:
+          SSH_KEY: ${{ secrets.SSH_PRIVATE_KEY }}
+        run: |
+          echo "$SSH_KEY" | base64 -d > /tmp/k
+          echo "key lines: $(wc -l < /tmp/k)"
+          echo "key bytes: $(wc -c < /tmp/k)"
+          echo "sha256(b64): $(echo "$SSH_KEY" | tr -d '\n' | sha256sum | cut -d' ' -f1)"
+          ssh-keygen -y -f /tmp/k >/dev/null 2>&1 && echo "KEYGEN_OK" || echo "KEYGEN_FAIL"
\ No newline at end of file