WordPress Plugin Development (Core)

Status: Production Ready ✅ Last Updated: 2025-11-06 Production Tested: Based on WordPress Plugin Handbook official documentation + Patchstack Security Database

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Auto-Trigger Keywords

Claude Code automatically discovers this skill when you mention:

Primary Keywords

• wordpress plugin
• wordpress plugin development
• wp plugin development
• wordpress coding standards
• wordpress plugin architecture

Secondary Keywords

• wordpress security
• wordpress hooks
• wordpress filters
• custom post type
• register_post_type
• register_taxonomy
• wordpress settings api
• wordpress rest api
• admin-ajax
• add_meta_box
• add_options_page
• register_rest_route
• $wpdb
• wpdb prepare

Security Keywords

• sanitize_text_field
• esc_html
• esc_attr
• esc_url
• wp_kses_post
• wp_nonce
• wp_verify_nonce
• wp_nonce_field
• check_ajax_referer
• current_user_can

Distribution & Updates Keywords

• github auto-updates
• github updates
• plugin auto-update
• plugin update checker
• wordpress plugin distribution
• git updater
• custom update server
• plugin versioning
• github releases
• private plugin updates
• license key updates
• plugin update api
• wordpress transients updates

Error-Based Keywords

• "wordpress sql injection"
• "wordpress xss"
• "wordpress csrf"
• "plugin activation 404"
• "nonce verification failed"
• "wordpress security vulnerability"
• "wordpress sanitization"
• "wordpress escaping"
• "plugin naming conflict"
• "custom post type 404"

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What This Skill Does

This skill provides comprehensive knowledge for building secure, standards-compliant WordPress plugins. It covers core patterns, security best practices, database interactions, hooks/filters, Settings API, custom post types, REST API, and AJAX implementations.

Core Capabilities

✅ Security Foundation - Prevents 20+ documented vulnerabilities (SQL injection, XSS, CSRF, etc.) ✅ Plugin Architecture - Simple, OOP, and PSR-4 patterns with templates ✅ WordPress APIs - Settings API, REST API, Custom Post Types, Taxonomies, Meta Boxes ✅ Database Patterns - Secure $wpdb queries, custom tables, transients ✅ Standards Compliance - WordPress Coding Standards, prefixing, ABSPATH checks ✅ Lifecycle Management - Activation, deactivation, uninstall hooks ✅ Distribution & Updates - GitHub auto-updates, Plugin Update Checker, versioning, releases ✅ Advanced Features - WP-CLI commands, scheduled events, internationalization

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Known Issues This Skill Prevents

Total: 20 documented issues prevented

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When to Use This Skill

✅ Use When:

• Creating new WordPress plugins from scratch
• Implementing security features (nonces, sanitization, escaping)
• Working with WordPress database ($wpdb, custom tables)
• Building admin interfaces (Settings API, meta boxes)
• Registering custom post types or taxonomies
• Creating REST API endpoints
• Handling AJAX requests
• Debugging plugin activation/deactivation issues
• Preventing security vulnerabilities
• Setting up auto-updates from GitHub or custom servers
• Distributing plugins outside WordPress.org
• Implementing license key validation for premium plugins

❌ Don't Use When:

• Building Gutenberg blocks → Use wordpress-gutenberg-blocks skill
• Creating WooCommerce extensions → Use woocommerce-extension skill
• Developing Gravity Forms add-ons → Use gravity-forms-addon skill
• Building Elementor widgets → Use elementor-widget skill

Claude Code will automatically combine this skill with specialized skills when needed.

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Quick Usage Example

# 1. Copy plugin template
cp -r templates/plugin-psr4/ ~/wp-content/plugins/my-plugin/

# 2. Install Composer dependencies (if using PSR-4)
cd ~/wp-content/plugins/my-plugin/
composer install

# 3. Activate plugin
wp plugin activate my-plugin

Result: Secure, standards-compliant WordPress plugin ready for development

Full instructions: See SKILL.md

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Token Efficiency Metrics

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Package Versions (Verified 2025-11-06)

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Dependencies

Prerequisites: None

Integrates With:

• wordpress-gutenberg-blocks (for block development)
• woocommerce-extension (for WooCommerce plugins)
• gravity-forms-addon (for Gravity Forms add-ons)
• elementor-widget (for Elementor widgets)

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File Structure

wordpress-plugin-core/
├── SKILL.md                      # Complete documentation (1,400+ lines)
├── README.md                     # This file
├── templates/
│   ├── plugin-simple/           # Simple functional plugin
│   ├── plugin-oop/              # Object-oriented plugin
│   ├── plugin-psr4/             # Modern PSR-4 plugin with Composer
│   └── examples/                # Meta boxes, settings, REST, AJAX
├── scripts/
│   ├── scaffold-plugin.sh       # Interactive plugin scaffolding
│   ├── check-security.sh        # Security audit tool
│   └── validate-headers.sh      # Plugin header validator
├── references/
│   ├── security-checklist.md    # Complete security audit
│   ├── hooks-reference.md       # Common WordPress hooks
│   ├── sanitization-guide.md    # All sanitization functions
│   ├── wpdb-patterns.md         # Database query patterns
│   └── common-errors.md         # Extended error documentation
└── assets/
    └── .gitignore               # Ignore vendor/, node_modules/

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Quick Reference

The 5-Step Security Foundation

// 1. Unique Prefix (4-5 chars)
function mypl_init() {}

// 2. ABSPATH Check (every PHP file)
if ( ! defined( 'ABSPATH' ) ) exit;

// 3. Sanitize Input, Escape Output
$clean = sanitize_text_field( $_POST['input'] );
echo esc_html( $output );

// 4. Nonces (CSRF Protection)
wp_nonce_field( 'mypl_action', 'mypl_nonce' );
wp_verify_nonce( $_POST['mypl_nonce'], 'mypl_action' );

// 5. Prepared Statements (SQL Injection Prevention)
$wpdb->prepare( "SELECT * FROM table WHERE id = %d", $id );

Plugin Header

<?php
/**
 * Plugin Name:       My Awesome Plugin
 * Plugin URI:        https://example.com/my-plugin/
 * Description:       Brief description of what this does
 * Version:           1.0.0
 * Requires at least: 5.9
 * Requires PHP:      7.4
 * Author:            Your Name
 * Author URI:        https://yoursite.com/
 * License:           GPL v2 or later
 * Text Domain:       my-plugin
 */

if ( ! defined( 'ABSPATH' ) ) exit;

Custom Post Type

function mypl_register_cpt() {
    register_post_type( 'book', array(
        'labels' => array(
            'name' => 'Books',
            'singular_name' => 'Book',
        ),
        'public' => true,
        'has_archive' => true,
        'show_in_rest' => true,
        'supports' => array( 'title', 'editor', 'thumbnail' ),
    ) );
}
add_action( 'init', 'mypl_register_cpt' );

// CRITICAL: Flush on activation
register_activation_hook( __FILE__, function() {
    mypl_register_cpt();
    flush_rewrite_rules();
} );

REST API Endpoint

add_action( 'rest_api_init', function() {
    register_rest_route( 'myplugin/v1', '/data', array(
        'methods' => 'GET',
        'callback' => 'mypl_rest_callback',
        'permission_callback' => function() {
            return current_user_can( 'edit_posts' );
        },
        'args' => array(
            'id' => array(
                'required' => true,
                'validate_callback' => 'is_numeric',
                'sanitize_callback' => 'absint',
            ),
        ),
    ) );
} );

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Official Documentation

• WordPress Plugin Handbook: https://developer.wordpress.org/plugins/
• WordPress Coding Standards: https://developer.wordpress.org/coding-standards/
• WordPress Security: https://developer.wordpress.org/apis/security/
• $wpdb Class Reference: https://developer.wordpress.org/reference/classes/wpdb/
• WordPress REST API: https://developer.wordpress.org/rest-api/
• Context7 Library: /websites/developer_wordpress

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Related Skills

• wordpress-gutenberg-blocks - Gutenberg block development (React, @wordpress/create-block)
• woocommerce-extension - WooCommerce-specific hooks, product types, payment gateways
• gravity-forms-addon - GFAddOn class, feed integrations, custom fields
• elementor-widget - Elementor widget registration, controls, rendering

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Contributing

Found an issue or have a suggestion?

• Open an issue: https://github.com/jezweb/claude-skills/issues
• See SKILL.md for detailed documentation

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License

MIT License - See main repo LICENSE file

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Production Tested: Based on official WordPress documentation + Patchstack Security Database Token Savings: ~67% (15k → 5k tokens) Error Prevention: 100% (20 documented issues prevented) Ready to use! See SKILL.md for complete setup.