diff --git a/modules/billing/add_to_cart.php b/modules/billing/add_to_cart.php
index 3101e688..efe3159a 100644
--- a/modules/billing/add_to_cart.php
+++ b/modules/billing/add_to_cart.php
@@ -5,6 +5,13 @@ require_once(__DIR__ . '/includes/config.inc.php');
 require_once(__DIR__ . '/includes/login_required.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 */
+
 // Start session if not already
 if (session_status() === PHP_SESSION_NONE) session_start();
 
diff --git a/modules/billing/admin_coupons.php b/modules/billing/admin_coupons.php
index a168e373..12a39375 100644
--- a/modules/billing/admin_coupons.php
+++ b/modules/billing/admin_coupons.php
@@ -3,6 +3,13 @@
 require_once(__DIR__ . '/includes/admin_auth.php');
 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 $table_prefix Table prefix for database tables */
+
 // Start session if not already started by admin_auth
 if (session_status() === PHP_SESSION_NONE) session_start();
 if (empty($_SESSION['admin_csrf'])) {
diff --git a/modules/billing/cart.php b/modules/billing/cart.php
index b0ea58be..5120ef35 100644
--- a/modules/billing/cart.php
+++ b/modules/billing/cart.php
@@ -42,6 +42,15 @@ if (session_status() === PHP_SESSION_NONE) {
 // Load 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 */
+/** @var string $SITE_BASE_URL Site base URL */
+/** @var string $SITE_DATA_DIR Data directory path */
+
 // Check if user is logged in
 $user_id = 0;
 if (isset($_SESSION['website_user_id']) && !empty($_SESSION['website_user_id'])) {
@@ -169,6 +178,7 @@ if ($_SERVER['REQUEST_METHOD'] === 'POST' && isset($_POST['apply_coupon'])) {
         } else {
             $error_message = 'Invalid coupon code.';
         }
+        }
     }
 }
 
diff --git a/modules/billing/forgot_password.php b/modules/billing/forgot_password.php
index 5e64fc97..72ab11d7 100644
--- a/modules/billing/forgot_password.php
+++ b/modules/billing/forgot_password.php
@@ -6,6 +6,13 @@ session_start();
 // 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/my_account.php b/modules/billing/my_account.php
index 7432bc5e..4a5d4650 100644
--- a/modules/billing/my_account.php
+++ b/modules/billing/my_account.php
@@ -30,6 +30,13 @@ if (!$is_logged_in) {
 // 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/my_servers.php b/modules/billing/my_servers.php
index 26502637..d5929b65 100644
--- a/modules/billing/my_servers.php
+++ b/modules/billing/my_servers.php
@@ -13,6 +13,13 @@ 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/renew_server.php b/modules/billing/renew_server.php
index 005bf7c7..f175cd0f 100644
--- a/modules/billing/renew_server.php
+++ b/modules/billing/renew_server.php
@@ -11,6 +11,13 @@ require_once(__DIR__ . '/includes/config.inc.php');
 require_once(__DIR__ . '/includes/login_required.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 */
+
 // Connect to DB (use mysqli like other website modules)
 $db = @mysqli_connect($db_host, $db_user, $db_pass, $db_name);
 if (!$db) {
diff --git a/modules/billing/reset_password.php b/modules/billing/reset_password.php
index 420107fa..2b80ca47 100644
--- a/modules/billing/reset_password.php
+++ b/modules/billing/reset_password.php
@@ -6,6 +6,13 @@ session_start();
 // 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) {