aitbotblocker-robots-txt.php

<?php
/**
Plugin Name: AI Bot Blocker
Description: Adds an option to the Reading settings to block AI bots via robots.txt.
Version: 1.0
Author: Ryan Neudorf
Author URI: https://ohryan.ca/
*/

function aibotblocker_settings_init()
{
    add_settings_field(
        'aibotblocker_block_bots', // ID
        'Block AI Bots', // Title
        'aibotblocker_settings_field_callback', // Callback
        'reading', // Page
        'default' // Section
    );

    register_setting('reading', 'aibotblocker_block_bots');
}

function aibotblocker_settings_field_callback()
{
    $value = get_option('aibotblocker_block_bots', 0);
    echo '<label for="aibotblocker_block_bots"><input type="checkbox" id="aibotblocker_block_bots" name="aibotblocker_block_bots" value="1" ' . checked(1, $value, false) . '/> '.__('Discourage AI training bots from scanning your site').'</label>';
}

add_action('admin_init', 'aibotblocker_settings_init');


function aibotblocker_filter_robots_txt($output, $public)
{
    $block_bots = get_option('aibotblocker_block_bots', 0);
    if ($block_bots) {
        $output .= "\nUser-agent: GPTBot\n";
        $output .= "Disallow: /\n";
    }
    return $output;
}

add_filter('robots_txt', 'aibotblocker_filter_robots_txt', 10, 2);