diff --git a/modules/billing/data/debug_cart.log b/modules/billing/data/debug_cart.log
new file mode 100644
index 00000000..b783902c
--- /dev/null
+++ b/modules/billing/data/debug_cart.log
@@ -0,0 +1,3 @@
+[2025-11-10 03:11:10] SHUTDOWN: no error
+[2025-11-10 03:11:21] SHUTDOWN: no error
+[2025-11-10 03:14:54] SHUTDOWN: no error
diff --git a/modules/billing/includes/admin_auth.php b/modules/billing/includes/admin_auth.php
index 8cdc6270..536ae5bf 100644
--- a/modules/billing/includes/admin_auth.php
+++ b/modules/billing/includes/admin_auth.php
@@ -25,6 +25,14 @@ if (empty($_SESSION['website_user_id'])) {
 // Require DB config and check role live from panel DB
 
 require_once(__DIR__ . '/config.inc.php');
+
+// Variables from config.inc.php (helps IDEs understand scope)
+/** @var string $db_host Database host */
+/** @var string $db_user Database user */
+/** @var string $db_pass Database password */
+/** @var string $db_name Database name */
+/** @var string $table_prefix Table prefix for database tables */
+
 // Use a local connection variable so we don't clash with pages that also use $db
 $auth_db = @mysqli_connect($db_host, $db_user, $db_pass, $db_name);
 if (!$auth_db) {
diff --git a/modules/billing/includes/menu.php b/modules/billing/includes/menu.php
index b5bc61c4..15a7faf7 100644
--- a/modules/billing/includes/menu.php
+++ b/modules/billing/includes/menu.php
@@ -27,6 +27,14 @@ $is_admin = false;
 if ($is_logged_in) {
   // load DB credentials
   require_once(__DIR__ . '/config.inc.php');
+  
+  // Variables from config.inc.php (helps IDEs understand scope)
+  /** @var string $db_host Database host */
+  /** @var string $db_user Database user */
+  /** @var string $db_pass Database password */
+  /** @var string $db_name Database name */
+  /** @var string $table_prefix Table prefix for database tables */
+  
   // Prefer reusing an existing $db if present, otherwise open a local connection
   $menu_db = null;
   $menu_db_opened = false;
diff --git a/modules/billing/includes/payment_processor.php b/modules/billing/includes/payment_processor.php
index bd126e86..bedd5e39 100644
--- a/modules/billing/includes/payment_processor.php
+++ b/modules/billing/includes/payment_processor.php
@@ -21,6 +21,13 @@ if (is_file($moduleConfig)) {
     error_log('[payment_processor] Module config not found: expected ' . $moduleConfig);
 }
 
+// Variables from config.inc.php (helps IDEs understand scope)
+/** @var string $db_host Database host */
+/** @var string $db_user Database user */
+/** @var string $db_pass Database password */
+/** @var string $db_name Database name */
+/** @var string $table_prefix Table prefix for database tables */
+
 // Normalize table prefix variable: many files use $table_prefix (lowercase)
 if (!isset($TABLE_PREFIX) && isset($table_prefix)) {
     $TABLE_PREFIX = $table_prefix;
diff --git a/modules/billing/login.php b/modules/billing/login.php
index 6ca5a697..c978f8ef 100644
--- a/modules/billing/login.php
+++ b/modules/billing/login.php
@@ -13,6 +13,13 @@ error_reporting(E_ALL);
 require_once(__DIR__ . '/includes/config.inc.php');
 require_once(__DIR__ . '/includes/log.php');
 
+// Variables from config.inc.php (helps IDEs understand scope)
+/** @var string $db_host Database host */
+/** @var string $db_user Database user */
+/** @var string $db_pass Database password */
+/** @var string $db_name Database name */
+/** @var string $table_prefix Table prefix for database tables */
+
 // Determine site root up to /_website so we can enforce absolute redirects within this site
 $script = $_SERVER['SCRIPT_NAME'] ?? '';
 $pos = strpos($script, '/_website');
diff --git a/modules/billing/order.php b/modules/billing/order.php
index ddcee005..8400aa22 100644
--- a/modules/billing/order.php
+++ b/modules/billing/order.php
@@ -26,6 +26,13 @@ require_once(__DIR__ . '/includes/login_required.php');
 // Include database configuration
 require_once(__DIR__ . '/includes/config.inc.php');
 
+// Variables from config.inc.php (helps IDEs understand scope)
+/** @var string $db_host Database host */
+/** @var string $db_user Database user */
+/** @var string $db_pass Database password */
+/** @var string $db_name Database name */
+/** @var string $table_prefix Table prefix for database tables */
+
 // Create database connection
 $db = mysqli_connect($db_host, $db_user, $db_pass, $db_name);
 if (!$db) {
diff --git a/modules/billing/payment_success.php b/modules/billing/payment_success.php
index b9993ef4..d467e0b2 100644
--- a/modules/billing/payment_success.php
+++ b/modules/billing/payment_success.php
@@ -7,6 +7,13 @@
 session_start();
 require_once(__DIR__ . '/includes/config.inc.php');
 
+// Variables from config.inc.php (helps IDEs understand scope)
+/** @var string $db_host Database host */
+/** @var string $db_user Database user */
+/** @var string $db_pass Database password */
+/** @var string $db_name Database name */
+/** @var string $table_prefix Table prefix for database tables */
+
 // Get PayPal order ID from URL
 $paypal_order_id = isset($_GET['order_id']) ? trim($_GET['order_id']) : '';
 
diff --git a/modules/billing/register.php b/modules/billing/register.php
index 5492002e..b61b2d43 100644
--- a/modules/billing/register.php
+++ b/modules/billing/register.php
@@ -3,6 +3,13 @@ session_name("gameservers_website");
 session_start();
 require_once(__DIR__ . '/includes/config.inc.php');
 
+// Variables from config.inc.php (helps IDEs understand scope)
+/** @var string $db_host Database host */
+/** @var string $db_user Database user */
+/** @var string $db_pass Database password */
+/** @var string $db_name Database name */
+/** @var string $table_prefix Table prefix for database tables */
+
 // Simple registration form (creates a user in {table_prefix}users with MD5 password)
 if ($_SERVER['REQUEST_METHOD'] === 'POST' && !empty($_POST['username']) && !empty($_POST['password'])) {
     $db = mysqli_connect($db_host, $db_user, $db_pass, $db_name);
diff --git a/modules/billing/serverlist.php b/modules/billing/serverlist.php
index 6bb4f3af..930a121f 100644
--- a/modules/billing/serverlist.php
+++ b/modules/billing/serverlist.php
@@ -14,6 +14,13 @@ error_reporting(E_ALL);
 // Include database configuration
 require_once(__DIR__ . '/includes/config.inc.php');
 
+// Variables from config.inc.php (helps IDEs understand scope)
+/** @var string $db_host Database host */
+/** @var string $db_user Database user */
+/** @var string $db_pass Database password */
+/** @var string $db_name Database name */
+/** @var string $table_prefix Table prefix for database tables */
+
 // Create database connection
 $db = mysqli_connect($db_host, $db_user, $db_pass, $db_name);
 if (!$db) {