// The parent::start_el returns the whole HTML string. We'll use string replacement or regex to inject our fields. // Detailed 'start_el' overriding is safer but massive. Injection is cleaner if done right. // However, the standard way is to completely override start_el. // Since I cannot copy 400 lines of WP core code safely without risking version mismatch, // I will use a known hook 'wp_nav_menu_item_custom_fields' (Standard since WP 5.4). // Wait, 'wp_nav_menu_item_custom_fields' is the BEST way. // If that hook exists, we don't even need to override the Walker class entirely, // we just need to hook into it. // But wait, the user instructions specifically asked for extending the menu editor. // WP 5.4+ added `wp_nav_menu_item_custom_fields`. // Using that hook is "Extending WordPress Menu Editor". // Let's refactor `class-nexus-menu-admin.php` to use the hook instead of the Walker if possible? // Actually, let's keep the Walker file but make it mostly empty or just use the hook inside it // if we were forced to specific positions. // But the standard `wp_nav_menu_item_custom_fields` fires precisely where we want custom fields. // Refactor plan: // 1. I will NOT override start_el massively. // 2. I will use the `wp_nav_menu_item_custom_fields` action. // However, I still need this file to potentially load that logic if I want to keep it separated. // But strictly speaking, if I use the hook, I don't need a custom Walker class *just* for editing, unless I want to change the structure. // Let's stick to the hook in the Admin class for simplicity and robustness. // BUT, I already registered the walker in Admin class: // `add_filter( 'wp_edit_nav_menu_walker', ... )` // I'll revert that or simply allow this class to exist but maybe do nothing if I pivot to hooks. // Actually, let's just do the hook method in this file? // No, `wp_edit_nav_menu_walker` filter expects a CLASS NAME string. // If I return 'Nexus_Menu_Walker', WP uses it. // If I don't filter it, WP uses default. // Using the default + `wp_nav_menu_item_custom_fields` is strictly better for compatibility. // So, I will UPDATE `class-nexus-menu-admin.php` to remove the walker filter and add the action hook. // And I will DELETE the need for this complex walker file. // But wait, "Mega Menu" usually implies changing the structure slightly or visual cues that might require a Walker. // For the *Editor*, the hook is fine. // For the *Frontend*, we definitely need a Walker. // Let's proceed with creating a Frontend Walker later. // For this step, I will use `class-nexus-menu-walker.php` to hold the "render_custom_fields" function // and simple helper methods, but we won't extend Walker_Nav_Menu_Edit. // Actually, I'll abide by my previous write. I'll overwrite `class-nexus-menu-admin.php` to use the hook. // It's much cleaner. } } // Pivot: I will effectively skip this file or make it a dummy, and update Admin class. // Better yet, I'll use this file to store the function used by the hook to keep `Admin` class clean.