Add cross-domain tracking support (v1.2.0)

Add linker domains setting to Advanced tab for cross-domain measurement.
Outputs gtag('set','linker') before config call so GA4 appends the _gl
parameter to links pointing at configured domains.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

admin/views/settings-advanced.php

@@ -55,6 +55,20 @@ if ( ! defined( 'ABSPATH' ) ) {
 				</p>
 			</td>
 		</tr>
+		<tr>
+			<th scope="row">
+				<label for="cross_domain_domains"><?php esc_html_e( 'Cross-Domain Tracking', 'att-consent' ); ?></label>
+			</th>
+			<td>
+				<textarea name="cross_domain_domains" id="cross_domain_domains" rows="4" class="large-text code"><?php echo esc_textarea( $settings['cross_domain_domains'] ); ?></textarea>
+				<p class="description">
+					<?php esc_html_e( 'Enter one domain per line for cross-domain measurement. The linker parameter will be appended to URLs pointing to these domains, allowing unified user tracking across sites.', 'att-consent' ); ?>
+				</p>
+				<p class="description">
+					<?php esc_html_e( 'Example: bookingengine.myguestdiary.com', 'att-consent' ); ?>
+				</p>
+			</td>
+		</tr>
 	</table>
 
 	<h2><?php esc_html_e( 'Google Consent Mode v2 Signal Reference', 'att-consent' ); ?></h2>

att-consent.php

@@ -3,7 +3,7 @@
  * Plugin Name: ATT Consent
  * Plugin URI:  https://github.com/att-consent/att-consent
  * Description: Google Consent Mode v2 cookie consent with session attribution preservation, custom script management, and full gtag.js/GTM support.
- * Version:     1.1.0
+ * Version:     1.2.0
  * Requires at least: 6.0
  * Requires PHP: 7.4
  * Author:      ATT Consent
@@ -18,7 +18,7 @@ if ( ! defined( 'ABSPATH' ) ) {
 	exit;
 }
 
-define( 'ATT_CC_VERSION', '1.1.0' );
+define( 'ATT_CC_VERSION', '1.2.0' );
 define( 'ATT_CC_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );
 define( 'ATT_CC_PLUGIN_URL', plugin_dir_url( __FILE__ ) );
 define( 'ATT_CC_PLUGIN_BASENAME', plugin_basename( __FILE__ ) );

includes/class-admin.php

@@ -226,6 +226,18 @@ class ATT_Consent_Admin {
 				if ( $settings['wait_for_update'] > 10000 ) {
 					$settings['wait_for_update'] = 10000;
 				}
+
+				// Cross-domain tracking: sanitize each domain line.
+				$raw_domains = $_POST['cross_domain_domains'] ?? '';
+				$lines       = array_filter( array_map( 'trim', explode( "\n", $raw_domains ) ) );
+				$clean       = array();
+				foreach ( $lines as $line ) {
+					$domain = sanitize_text_field( $line );
+					if ( '' !== $domain ) {
+						$clean[] = $domain;
+					}
+				}
+				$settings['cross_domain_domains'] = implode( "\n", $clean );
 				break;
 		}
 

includes/class-att-consent.php

@@ -60,9 +60,10 @@ class ATT_Consent {
 		'cat_marketing_desc'  => 'These cookies are used to deliver advertisements relevant to you.',
 
 		// Advanced.
-		'url_passthrough'    => true,
+		'url_passthrough'        => true,
-		'ads_data_redaction' => true,
+		'ads_data_redaction'     => true,
-		'wait_for_update'    => 500,
+		'wait_for_update'        => 500,
+		'cross_domain_domains'   => '',
 	);
 
 	/**

includes/class-frontend.php

@@ -57,6 +57,14 @@ class ATT_Consent_Frontend {
 			'tracking_mode'   => $s['tracking_mode'],
 		);
 
+		// Cross-domain tracking domains.
+		if ( ! empty( $s['cross_domain_domains'] ) ) {
+			$domains = array_filter( array_map( 'trim', explode( "\n", $s['cross_domain_domains'] ) ) );
+			if ( ! empty( $domains ) ) {
+				$config['linker_domains'] = array_values( $domains );
+			}
+		}
+
 		// In basic mode, pass the tracking snippet for deferred injection.
 		if ( 'basic' === $s['consent_mode'] ) {
 			$config['tracking_snippet'] = $this->get_tracking_snippet();
@@ -107,6 +115,7 @@ wait_for_update:c.wait_for_update||500
 });
 window.attCCHasConsent=false;
 }
+if(c.linker_domains&&c.linker_domains.length){g('set','linker',{'domains':c.linker_domains});}
 if(!sessionStorage.getItem('att_cc_attr')){
 var p=new URLSearchParams(window.location.search);
 var a={