diff --git a/2meet-data-optimizer-hivepress-addon.php b/2meet-data-optimizer-hivepress-addon.php
index 5c81ba5..d4c64cb 100644
--- a/2meet-data-optimizer-hivepress-addon.php
+++ b/2meet-data-optimizer-hivepress-addon.php
@@ -29,6 +29,7 @@ define( 'TMDO_HIVEPRESS_FILE', __FILE__ );
 
 require_once TMDO_HIVEPRESS_PATH . 'includes/class-tmdo-hivepress-bootstrap.php';
 
+require_once TMDO_HIVEPRESS_PATH . 'includes/back-compat-aliases.php';
 /**
  * Phase 3 任務：完成本 AddOn 的 includes/ 實作。
  *
diff --git a/includes/back-compat-aliases.php b/includes/back-compat-aliases.php
new file mode 100644
index 0000000..6eb79a0
--- /dev/null
+++ b/includes/back-compat-aliases.php
@@ -0,0 +1,71 @@
+<?php
+/**
+ * Backward-compat class aliases for the hivepress AddOn.
+ *
+ * Sister plugins and third-party code may still reference the WPDO_* class
+ * names from wp-data-optimizer. The core plugin aliases its own classes in
+ * class-tmdo-back-compat.php, but it runs before AddOns load (plugins_loaded:4
+ * vs :6), so each AddOn must alias its own classes here.
+ *
+ * @package TMDO
+ */
+
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+add_action(
+	'plugins_loaded',
+	static function () {
+		$aliases = array(
+			'TMDO_Admin_HivePress' => 'WPDO_Admin_HivePress',
+			'TMDO_CLI_HivePress' => 'WPDO_CLI_HivePress',
+			'TMDO_Favorites_Interceptor' => 'WPDO_Favorites_Interceptor',
+			'TMDO_HPCT_Import' => 'WPDO_HPCT_Import',
+			'TMDO_HP_Bootstrap' => 'WPDO_HP_Bootstrap',
+			'TMDO_HivePress' => 'WPDO_HivePress',
+			'TMDO_HivePress_Attribute_Bridge' => 'WPDO_HivePress_Attribute_Bridge',
+			'TMDO_HivePress_Benchmark' => 'WPDO_HivePress_Benchmark',
+			'TMDO_HivePress_Blocks_Adapter' => 'WPDO_HivePress_Blocks_Adapter',
+			'TMDO_HivePress_Bookings_Adapter' => 'WPDO_HivePress_Bookings_Adapter',
+			'TMDO_HivePress_Bootstrap' => 'WPDO_HivePress_Bootstrap',
+			'TMDO_HivePress_Comment_Router' => 'WPDO_HivePress_Comment_Router',
+			'TMDO_HivePress_Conflict_Guard' => 'WPDO_HivePress_Conflict_Guard',
+			'TMDO_HivePress_Core_Adapter' => 'WPDO_HivePress_Core_Adapter',
+			'TMDO_HivePress_Cron_Optimizer' => 'WPDO_HivePress_Cron_Optimizer',
+			'TMDO_HivePress_Detector' => 'WPDO_HivePress_Detector',
+			'TMDO_HivePress_Favorites_Adapter' => 'WPDO_HivePress_Favorites_Adapter',
+			'TMDO_HivePress_Marketplace_Adapter' => 'WPDO_HivePress_Marketplace_Adapter',
+			'TMDO_HivePress_Memberships_Adapter' => 'WPDO_HivePress_Memberships_Adapter',
+			'TMDO_HivePress_Messages_Adapter' => 'WPDO_HivePress_Messages_Adapter',
+			'TMDO_HivePress_REST' => 'WPDO_HivePress_REST',
+			'TMDO_HivePress_Requests_Adapter' => 'WPDO_HivePress_Requests_Adapter',
+			'TMDO_HivePress_Reviews_Adapter' => 'WPDO_HivePress_Reviews_Adapter',
+			'TMDO_HivePress_Seo_Adapter' => 'WPDO_HivePress_Seo_Adapter',
+			'TMDO_HivePress_Social_Links_Adapter' => 'WPDO_HivePress_Social_Links_Adapter',
+			'TMDO_HivePress_Statistics_Adapter' => 'WPDO_HivePress_Statistics_Adapter',
+			'TMDO_HivePress_Suitability_Scorer' => 'WPDO_HivePress_Suitability_Scorer',
+			'TMDO_HivePress_Tags_Adapter' => 'WPDO_HivePress_Tags_Adapter',
+			'TMDO_Hivepress_Term_Comment_Fields' => 'WPDO_Hivepress_Term_Comment_Fields',
+			'TMDO_Hivepress_Transient_Filter' => 'WPDO_Hivepress_Transient_Filter',
+			'TMDO_Listing_Meta_Interceptor' => 'WPDO_Listing_Meta_Interceptor',
+			'TMDO_Listing_Meta_Query' => 'WPDO_Listing_Meta_Query',
+			'TMDO_Listing_Stats' => 'WPDO_Listing_Stats',
+			'TMDO_Memberships_Interceptor' => 'WPDO_Memberships_Interceptor',
+			'TMDO_Memberships_Query' => 'WPDO_Memberships_Query',
+			'TMDO_Messages_Interceptor' => 'WPDO_Messages_Interceptor',
+			'TMDO_Messages_Query' => 'WPDO_Messages_Query',
+			'TMDO_Requests_Interceptor' => 'WPDO_Requests_Interceptor',
+			'TMDO_Requests_Query' => 'WPDO_Requests_Query',
+			'TMDO_Reviews_Interceptor' => 'WPDO_Reviews_Interceptor',
+			'TMDO_Reviews_Query' => 'WPDO_Reviews_Query',
+			'TMDO_Statistics_Interceptor' => 'WPDO_Statistics_Interceptor',
+		);
+		foreach ( $aliases as $tmdo_class => $wpdo_alias ) {
+			if ( class_exists( $tmdo_class, false ) && ! class_exists( $wpdo_alias, false ) ) {
+				class_alias( $tmdo_class, $wpdo_alias );
+			}
+		}
+	},
+	7
+);