diff --git a/template/Install-CIToolchain-Linux2404.sh b/template/Install-CIToolchain-Linux2404.sh
index 593e568..a7fa58d 100644
--- a/template/Install-CIToolchain-Linux2404.sh
+++ b/template/Install-CIToolchain-Linux2404.sh
@@ -51,12 +51,15 @@ assert_step() {
 # --- Step 1: apt update + upgrade ---
 echo ""
 echo "=== Step 1: apt update + upgrade ==="
+# apt-get update always runs — package index must be fresh to locate packages.
+# --skip-update only skips the (slow) full upgrade.
+sudo DEBIAN_FRONTEND=noninteractive apt-get update -qq
+assert_step "apt update completed" true
 if [ "${SKIP_UPDATE:-0}" = "0" ]; then
-    sudo DEBIAN_FRONTEND=noninteractive apt-get update -qq
     sudo DEBIAN_FRONTEND=noninteractive apt-get upgrade -y -qq
-    assert_step "apt update + upgrade completed" true
+    assert_step "apt upgrade completed" true
 else
-    echo "  [SKIP] --skip-update flag set"
+    echo "  [SKIP] --skip-update flag set — upgrade skipped (index still refreshed)"
 fi
 
 # --- Step 2: build essentials ---
@@ -88,6 +91,14 @@ assert_step "git available"  command -v git
 assert_step "7z available"   command -v 7z
 assert_step "curl available" command -v curl
 
+# --- Step 4a: GTK/GObject + headless display (PyGObject GUI tests) ---
+echo ""
+echo "=== Step 4a: GTK4 / GObject introspection + Xvfb ==="
+sudo DEBIAN_FRONTEND=noninteractive apt-get install -y -qq \
+    python3-gi gir1.2-gtk-4.0 xvfb
+assert_step "python3-gi importable" python3 -c "import gi"
+assert_step "xvfb available"        command -v Xvfb
+
 # --- Step 4b: .NET SDK (optional) ---
 echo ""
 echo "=== Step 4b: .NET SDK (optional) ==="