Cannot register a custom WP-CLI command

Question

I am working on a custom plugin and one of it's functionailities is to scan all the posts/pages on daily basis and update a meta-data in the database. I also wanted to create a custom WP-CLI command for system administrators' convenience. Here is my code:

<?php
if( defined( 'WP_CLI' ) && WP_CLI ) {
    /**
     * Scans all public posts and updates the custom_plugin_last_scan post_meta.
     *
     * ## EXAMPLES
     *
     *     wp posts scan --post_type=post --status=draft
     *
     * @when after_wp_load
     */
    class ScanPostsCommand {

        /**
         * Scans all public posts and updates the custom_plugin_last_scan meta key.
         *
         * ## OPTIONS
         *
         * [--post_type=<post_type>]
         * : Post type to scan. Default is 'any'.
         *
         * [--status=<status>]
         * : Post status to scan. Default is 'publish'.
         */
        public function __invoke($args, $assoc_args) {
            WP_CLI::line('Scanning posts...');

            $post_type = isset($assoc_args['post_type']) ? $assoc_args['post_type'] : 'any';
            $post_status = isset($assoc_args['status']) ? $assoc_args['status'] : 'publish';

            $query = new WP_Query(array(
                'post_type' => $post_type,
                'post_status' => $post_status,
                'posts_per_page' => -1,
            ));

            $scanned_posts = 0;
            while ($query->have_posts()) {
                $query->the_post();
                update_post_meta(get_the_ID(), 'custom_plugin_last_scan', current_time('mysql'));
                $scanned_posts++;
            }
            wp_reset_postdata();

            WP_CLI::success("Scanned $scanned_posts posts and updated their meta data.");
        }
    }

    WP_CLI::add_command('posts scan', 'ScanPostsCommand');
}
?>

But when I run the command wp posts scan it does not work and generate an error

Error: 'posts' is not a registered wp command. See 'wp help' for available commands.
Did you mean 'post'?

I have WP-CLI installed on my system. When I run wp --info I get below results:

OS:     Darwin 24.0.0 Darwin Kernel Version 24.0.0: Thu May 30 21:32:37 PDT 2024; root:xnu-11215.0.31.511.2~1/RELEASE_ARM64_T6030 arm64
Shell:  /bin/zsh
PHP binary:     /opt/homebrew/Cellar/php/8.3.2/bin/php
PHP version:    8.3.2
php.ini used:   /opt/homebrew/etc/php/8.3/php.ini
MySQL binary:
MySQL version:
SQL modes:
WP-CLI root dir:        phar://wp-cli.phar/vendor/wp-cli/wp-cli
WP-CLI vendor dir:      phar://wp-cli.phar/vendor
WP_CLI phar path:       /Users/farhanali/Sites/wordpress/wp-content/plugins/custom-plugin/app/admin-pages
WP-CLI packages dir:
WP-CLI cache dir:       /Users/farhanali/.wp-cli/cache
WP-CLI global config:
WP-CLI project config:
WP-CLI version: 2.10.0

Answer 1

You are trying to add a subcommand to a non-existing command posts according to the error message.

Modify it to a single word command like posts-scan or add a subcommand to an existing command, like post.