diff --git a/.github/workflows/e2e.yaml b/.github/workflows/e2e.yaml
index 401e5db..8cf4014 100644
--- a/.github/workflows/e2e.yaml
+++ b/.github/workflows/e2e.yaml
@@ -49,14 +49,14 @@ jobs:
         run: |
           set -euo pipefail
           echo "=== Runner environment diagnostic ==="
-          echo "HOME=$HOME"
-          echo "KUBECONFIG=$KUBECONFIG"
-          echo "ACTIONS_KUBECONFIG=$ACTIONS_KUBECONFIG"
-          echo "RUNNER_CONFIG=$RUNNER_CONFIG"
-          echo "RUNNER_CONFIG_DIR=$RUNNER_CONFIG_DIR"
+          echo "HOME=${HOME:-}"
+          echo "KUBECONFIG=${KUBECONFIG:-}"
+          echo "ACTIONS_KUBECONFIG=${ACTIONS_KUBECONFIG:-}"
+          echo "RUNNER_CONFIG=${RUNNER_CONFIG:-}"
+          echo "RUNNER_CONFIG_DIR=${RUNNER_CONFIG_DIR:-}"
           echo ""
           echo "=== Checking known kubeconfig locations ==="
-          for path in /runner/config /home/runner/.kube/config "$HOME/.kube/config" "$HOME/.kube"; do
+          for path in /runner/config /home/runner/.kube/config "${HOME:-}/.kube/config" "${HOME:-}/.kube"; do
             if [ -f "$path" ]; then
               echo "FOUND kubeconfig at: $path"
             elif [ -d "$path" ]; then
@@ -70,14 +70,14 @@ jobs:
           echo "=== In-cluster service account check ==="
           if [ -f /var/run/secrets/kubernetes.io/serviceaccount/token ]; then
             echo "Service account token present — in-cluster mode available"
-            echo "KUBERNETES_SERVICE_HOST=$KUBERNETES_SERVICE_HOST"
-            echo "KUBERNETES_SERVICE_PORT=$KUBERNETES_SERVICE_PORT"
+            echo "KUBERNETES_SERVICE_HOST=${KUBERNETES_SERVICE_HOST:-}"
+            echo "KUBERNETES_SERVICE_PORT=${KUBERNETES_SERVICE_PORT:-}"
           else
             echo "No service account token at /var/run/secrets/kubernetes.io/serviceaccount/"
           fi
           echo ""
           echo "=== Attempting kubeconfig from in-cluster env ==="
-          if [ -n "$KUBERNETES_SERVICE_HOST" ]; then
+          if [ -n "${KUBERNETES_SERVICE_HOST:-}" ]; then
             echo "In-cluster: yes"
             kubectl config view --raw 2>&1 | head -5 || echo "kubectl config view failed"
           else
@@ -90,8 +90,8 @@ jobs:
           elif [ -f /home/runner/.kube/config ]; then
             echo "KUBECONFIG=/home/runner/.kube/config" >> "$GITHUB_ENV"
             echo "Using kubeconfig from /home/runner/.kube/config"
-          elif [ -f "$HOME/.kube/config" ]; then
-            echo "KUBECONFIG=$HOME/.kube/config" >> "$GITHUB_ENV"
+          elif [ -f "${HOME:-}/.kube/config" ]; then
+            echo "KUBECONFIG=${HOME:-}/.kube/config" >> "$GITHUB_ENV"
             echo "Using kubeconfig from HOME"
           else
             echo "::error::No kubeconfig found in /runner/config, /home/runner/.kube/config, or HOME"