Release version 1.1.19 - Enhanced duplicate detection

Fixed persistent duplicate settings page by improving duplicate detection
to check by class type and ID instead of strict instance comparison.

Issue:
- Strict instance comparison (===) failed to detect duplicates
- Different object instances of same class not caught by previous check
- Settings page still appearing twice despite singleton and instance caching

Solution:
- Changed duplicate detection from instance comparison to type/ID checks
- Added instanceof WC_TPP_Settings check
- Added get_id() method check for ID 'tier_package_prices'
- Added direct id property check as fallback
- Multiple layers of detection to catch duplicates regardless of how created

Fixes:
- Settings page rendering twice in WooCommerce backend
- Duplicate detection failing for different instances of same class

Changes:
- Enhanced add_settings_page() with multi-layer duplicate detection
- Checks: instanceof, get_id(), and id property
- Returns early if any existing page matches criteria

Technical Details:
- Strict comparison only works if exact same object instance
- Different instances (even of same class/ID) fail === check
- instanceof checks class type regardless of which instance
- ID checks ensure no duplicate pages with same identifier
- Fallback checks handle different WooCommerce versions/implementations

Updated Files:
- includes/class-wc-tpp-admin.php (enhanced duplicate detection)
- wc-tier-and-package-prices.php (version 1.1.19)
- composer.json (version 1.1.19)
- CHANGELOG.md (v1.1.19 section)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -5,6 +5,91 @@ All notable changes to WooCommerce Tier and Package Prices will be documented in
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.1.19] - 2025-12-22
+
+### Fixed
+
+- Settings page still appearing twice despite instance caching
+- Duplicate detection using strict instance comparison failing for different object instances
+
+### Changed
+
+- Enhanced duplicate detection to check by class type and ID instead of instance
+- Added `instanceof WC_TPP_Settings` check
+- Added ID-based duplicate detection via `get_id()` method and direct property access
+- Multiple fallback checks to catch duplicates regardless of instance identity
+
+### Technical Details
+
+- Previous strict comparison (`===`) failed when different instances of same class existed
+- New approach checks: instanceof, get_id() method, and id property
+- Returns early if any settings page with ID 'tier_package_prices' found
+- Prevents duplicates even if settings instance recreated or serialized
+
+## [1.1.18] - 2025-12-22
+
+### Fixed
+
+- **ROOT CAUSE IDENTIFIED**: Settings page rendering twice due to automatic instantiation in settings file
+- Settings file being included multiple times via Composer autoloader creating duplicate instances
+
+### Changed
+
+- Removed `return new WC_TPP_Settings();` from bottom of settings file
+- Changed admin class to explicitly instantiate settings with `new WC_TPP_Settings()`
+- Changed from `include` to `require_once` for settings file to prevent multiple loads
+
+### Technical Details
+
+- Settings file (class-wc-tpp-settings.php) was creating instance automatically on include
+- File is in Composer's classmap, so when autoloaded it executed instantiation again
+- Each include/autoload created new instance even with singleton pattern in admin class
+- Solution: Remove automatic instantiation, use `require_once` + explicit `new` in admin class
+- Now settings instance only created once, explicitly, when needed by filter
+- Composer autoload can load class definition without side effects
+
+## [1.1.17] - 2025-12-22
+
+### Fixed
+
+- Settings page still rendering twice despite singleton pattern in v1.1.16
+- Filter adding settings instance to array multiple times when called repeatedly
+
+### Changed
+
+- Added duplicate detection in `add_settings_page()` filter method
+- Filter now checks if settings instance already exists in array before adding
+
+### Technical Details
+
+- Added foreach loop to check existing settings pages in array
+- Uses strict comparison (`===`) to detect if exact instance already present
+- Returns early if settings instance found, preventing duplicate array entries
+- Complements singleton pattern from v1.1.16 with array-level duplicate prevention
+- Handles edge case where WooCommerce calls filter multiple times
+
+## [1.1.16] - 2025-12-22
+
+### Fixed
+
+- Settings page still rendering twice in WooCommerce backend despite v1.1.15 fix
+- Multiple instantiation of WC_TPP_Admin and WC_TPP_Settings classes
+
+### Changed
+
+- Implemented singleton pattern for WC_TPP_Admin class with `get_instance()` method
+- Made WC_TPP_Admin constructor private to prevent direct instantiation
+- Added static caching of WC_TPP_Settings instance to prevent duplicate creation
+- Changed class instantiation from `new WC_TPP_Admin()` to `WC_TPP_Admin::get_instance()`
+
+### Technical Details
+
+- Added `private static $instance` property to WC_TPP_Admin class
+- Added `private static $settings_instance` property to cache settings page instance
+- Modified `add_settings_page()` to check and reuse cached settings instance
+- Ensures only one instance of each class exists throughout plugin lifecycle
+- Prevents duplicate filter registrations even if called multiple times
+
 ## [1.1.15] - 2025-12-22
 
 ### Fixed

composer.json

@@ -1,7 +1,7 @@
 {
     "name": "magdev/wc-tier-package-prices",
     "description": "WooCommerce plugin for tier pricing and package prices with Twig templates",
-    "version": "1.1.15",
+    "version": "1.1.19",
     "type": "wordpress-plugin",
     "license": "GPL-2.0-or-later",
     "authors": [

includes/class-wc-tpp-admin.php

@@ -10,7 +10,17 @@ if (!defined('ABSPATH')) {
 if (!class_exists('WC_TPP_Admin')) {
     class WC_TPP_Admin {
 
-    public function __construct() {
+    private static $instance = null;
+    private static $settings_instance = null;
+
+    public static function get_instance() {
+        if (null === self::$instance) {
+            self::$instance = new self();
+        }
+        return self::$instance;
+    }
+
+    private function __construct() {
         add_filter('woocommerce_get_settings_pages', array($this, 'add_settings_page'));
         add_action('admin_enqueue_scripts', array($this, 'enqueue_admin_scripts'));
     }
@@ -19,7 +29,32 @@ if (!class_exists('WC_TPP_Admin')) {
      * Add settings page to WooCommerce settings
      */
     public function add_settings_page($settings) {
-        $settings[] = include WC_TPP_PLUGIN_DIR . 'includes/class-wc-tpp-settings.php';
+        if (null === self::$settings_instance) {
+            require_once WC_TPP_PLUGIN_DIR . 'includes/class-wc-tpp-settings.php';
+            self::$settings_instance = new WC_TPP_Settings();
+        }
+
+        // Check if our settings page is already in the array to prevent duplicates
+        // Check by class type and ID instead of instance comparison
+        foreach ($settings as $settings_page) {
+            if ($settings_page instanceof WC_TPP_Settings) {
+                return $settings;
+            }
+            // Also check by ID property if it's a WC_Settings_Page
+            if (is_object($settings_page) &&
+                method_exists($settings_page, 'get_id') &&
+                $settings_page->get_id() === 'tier_package_prices') {
+                return $settings;
+            }
+            // Check id property directly
+            if (is_object($settings_page) &&
+                isset($settings_page->id) &&
+                $settings_page->id === 'tier_package_prices') {
+                return $settings;
+            }
+        }
+
+        $settings[] = self::$settings_instance;
         return $settings;
     }
 
@@ -31,5 +66,5 @@ if (!class_exists('WC_TPP_Admin')) {
     }
 }
 
-new WC_TPP_Admin();
+WC_TPP_Admin::get_instance();
 }

includes/class-wc-tpp-settings.php

@@ -141,5 +141,3 @@ if (!class_exists('WC_TPP_Settings')) {
     }
 }
 }
-
-return new WC_TPP_Settings();

wc-tier-and-package-prices.php

@@ -4,7 +4,7 @@
  * Plugin Name: WooCommerce Tier and Package Prices
  * Plugin URI: https://src.bundespruefstelle.ch/magdev/wc-tier-package-prices
  * Description: Add tier pricing and package prices to WooCommerce products with configurable quantities at fixed prices
- * Version: 1.1.15
+ * Version: 1.1.19
  * Author: Marco Graetsch
  * Author URI: https://src.bundespruefstelle.ch/magdev
  * Text Domain: wc-tier-package-prices
@@ -23,7 +23,7 @@ if (!defined('ABSPATH')) {
 
 // Define plugin constants
 if (!defined('WC_TPP_VERSION')) {
-    define('WC_TPP_VERSION', '1.1.15');
+    define('WC_TPP_VERSION', '1.1.19');
 }
 if (!defined('WC_TPP_PLUGIN_DIR')) {
     define('WC_TPP_PLUGIN_DIR', plugin_dir_path(__FILE__));