WordPress Development — Copilot Instructions

Goal: Generate WordPress code that is secure, performant, testable, and compliant with official WordPress practices. Prefer hooks, small functions, dependency injection (where sensible), and clear separation of concerns.

1) Core Principles

• Never modify WordPress core. Extend via actions and filters.
• For plugins, always include a header and guard direct execution in entry PHP files.
• Use unique prefixes or PHP namespaces to avoid global collisions.
• Enqueue assets; never inline raw

  <script>

  /

  <style>

  in PHP templates.
• Make user‑facing strings translatable and load the correct text domain.

Minimal plugin header & guard

<?php
defined('ABSPATH') || exit;
/**
 * Plugin Name: Awesome Feature
 * Description: Example plugin scaffold.
 * Version: 0.1.0
 * Author: Example
 * License: GPL-2.0-or-later
 * Text Domain: awesome-feature
 * Domain Path: /languages
 */

2) Coding Standards (PHP, JS, CSS, HTML)

• Follow WordPress Coding Standards (WPCS) and write DocBlocks for public APIs.
• PHP: Prefer strict comparisons (

  ===

  ,

  !==

  ) where appropriate. Be consistent with array syntax and spacing as per WPCS.
• JS: Match WordPress JS style; prefer

  @wordpress/*

  packages for block/editor code.
• CSS: Use BEM‑like class naming when helpful; avoid over‑specific selectors.
• PHP 7.4+ compatible patterns unless the project specifies higher. Avoid using features not supported by target WP/PHP versions.

Linting setup suggestions

<!-- phpcs.xml -->
<?xml version="1.0"?>
<ruleset name="Project WPCS">
  <description>WordPress Coding Standards for this project.</description>
  <file>./</file>
  <exclude-pattern>vendor/*</exclude-pattern>
  <exclude-pattern>node_modules/*</exclude-pattern>
  <rule ref="WordPress"/>
  <rule ref="WordPress-Docs"/>
  <rule ref="WordPress-Extra"/>
  <rule ref="PHPCompatibility"/>
  <config name="testVersion" value="7.4-"/>
</ruleset>

// composer.json (snippet)
{
  "require-dev": {
    "dealerdirect/phpcodesniffer-composer-installer": "^1.0",
    "wp-coding-standards/wpcs": "^3.0",
    "phpcompatibility/php-compatibility": "^9.0"
  },
  "scripts": {
    "lint:php": "phpcs -p",
    "fix:php": "phpcbf -p"
  }
}

// package.json (snippet)
{
  "devDependencies": {
    "@wordpress/eslint-plugin": "^x.y.z"
  },
  "scripts": {
    "lint:js": "eslint ."
  }
}

3) Security & Data Handling

• Escape on output, sanitize on input.
  • Escape:

    esc_html()

    ,

    esc_attr()

    ,

    esc_url()

    ,

    wp_kses_post()

    .
  • Sanitize:

    sanitize_text_field()

    ,

    sanitize_email()

    ,

    sanitize_key()

    ,

    absint()

    ,

    intval()

    .
• Capabilities & nonces for forms, AJAX, REST:
  • Add nonces with

    wp_nonce_field()

    and verify via

    check_admin_referer()

    /

    wp_verify_nonce()

    .
  • Restrict mutations with

    current_user_can( 'manage_options' /* or specific cap */ )

    .
• Database: always use

  $wpdb->prepare()

  with placeholders; never concatenate untrusted input.
• Uploads: validate MIME/type and use

  wp_handle_upload()

  /

  media_handle_upload()

  .

4) Internationalization (i18n)

• Wrap user‑visible strings with translation functions using your text domain:

  • __( 'Text', 'awesome-feature' )

    ,

    _x()

    ,

    esc_html__()

    .
• Load translations with

  load_plugin_textdomain()

  or

  load_theme_textdomain()

  .
• Keep a

  .pot

  in

  /languages

  and ensure consistent domain usage.

5) Performance

• Defer heavy logic to specific hooks; avoid expensive work on

  init

  /

  wp_loaded

  unless necessary.
• Use transients or object caching for expensive queries; plan invalidation.
• Enqueue only what you need and conditionally (front vs admin; specific screens/routes).
• Prefer paginated/parameterized queries over unbounded loops.

6) Admin UI & Settings

• Use Settings API for options pages; provide

  sanitize_callback

  for each setting.
• For tables, follow

  WP_List_Table

  patterns. For notices, use the admin notices API.
• Avoid direct HTML echoing for complex UIs; prefer templates or small view helpers with escaping.

7) REST API

• Register with

  register_rest_route()

  ; always set a

  permission_callback

  .
• Validate/sanitize request args via the

  args

  schema.
• Return

  WP_REST_Response

  or arrays/objects that map cleanly to JSON.

8) Blocks & Editor (Gutenberg)

• Use

  block.json

  +

  register_block_type()

  ; rely on

  @wordpress/*

  packages.
• Provide server render callbacks when needed (dynamic blocks).
• E2E tests should cover: insert block → edit → save → front‑end render.

9) Asset Loading

add_action('wp_enqueue_scripts', function () {
  wp_enqueue_style(
    'af-frontend',
    plugins_url('assets/frontend.css', __FILE__),
    [],
    '0.1.0'
  );

  wp_enqueue_script(
    'af-frontend',
    plugins_url('assets/frontend.js', __FILE__),
    [ 'wp-i18n', 'wp-element' ],
    '0.1.0',
    true
  );
});

• Use

  wp_register_style/script

  to register first if multiple components depend on the same assets.
• For admin screens, hook into

  admin_enqueue_scripts

  and check screen IDs.

10) Testing

PHP Unit/Integration

• Use WordPress test suite with

  PHPUnit

  and

  WP_UnitTestCase

  .
• Test: sanitization, capability checks, REST permissions, DB queries, hooks.
• Prefer factories (

  self::factory()->post->create()

  etc.) to set up fixtures.

<!-- phpunit.xml.dist (minimal) -->
<?xml version="1.0" encoding="UTF-8"?>
<phpunit bootstrap="tests/bootstrap.php" colors="true">
  <testsuites>
    <testsuite name="Plugin Test Suite">
      <directory suffix="Test.php">tests/</directory>
    </testsuite>
  </testsuites>
</phpunit>

// tests/bootstrap.php (minimal sketch)
<?php
$_tests_dir = getenv('WP_TESTS_DIR') ?: '/tmp/wordpress-tests-lib';
require_once $_tests_dir . '/includes/functions.php';
tests_add_filter( 'muplugins_loaded', function () {
  require dirname(__DIR__) . '/awesome-feature.php';
} );
require $_tests_dir . '/includes/bootstrap.php';

E2E

• Use Playwright (or Puppeteer) for editor/front‑end flows.
• Cover basic user journeys and regressions (block insertion, settings save, front‑end render).

11) Documentation & Commits

• Keep

  README.md

  up to date: install, usage, capabilities, hooks/filters, and test instructions.
• Use clear, imperative commit messages; reference issues/tickets and summarize impact.

12) What Copilot Must Ensure (Checklist)

• ✅ Unique prefixes/namespaces; no accidental globals.
• ✅ Nonce + capability checks for any write action (AJAX/REST/forms).
• ✅ Inputs sanitized; outputs escaped.
• ✅ User‑visible strings wrapped in i18n with correct text domain.
• ✅ Assets enqueued via APIs (no inline script/style).
• ✅ Tests added/updated for new behaviors.
• ✅ Code passes PHPCS (WPCS) and ESLint where applicable.
• ✅ Avoid direct DB concatenation; always prepare queries.