my_extension/
├── Classes/
│   ├── Controller/
│   ├── Domain/
│   │   ├── Model/
│   │   └── Repository/
│   ├── Service/
│   └── EventListener/
├── Configuration/
│   ├── Backend/
│   │   └── Modules.php
│   ├── Icons.php
│   ├── Services.yaml
│   ├── TCA/
│   │   ├── Overrides/
│   │   └── tx_myext_*.php
│   └── TypoScript/
│       ├── setup.typoscript
│       └── constants.typoscript
├── Documentation/
│   ├── Index.rst
│   └── guides.xml
├── Resources/
│   ├── Private/
│   │   ├── Language/
│   │   ├── Layouts/
│   │   ├── Partials/
│   │   └── Templates/
│   └── Public/
│       ├── Css/
│       ├── Icons/
│       └── JavaScript/
├── Tests/
│   ├── Functional/
│   └── Unit/
├── composer.json
├── ext_emconf.php
├── ext_localconf.php
└── ext_tables.php

<?php

declare(strict_types=1);

namespace Vendor\MyExtension\Service;

use Doctrine\DBAL\ParameterType;
use Psr\Log\LoggerInterface;
use TYPO3\CMS\Core\Database\ConnectionPool;

final readonly class ItemService
{
    public function __construct(
        private ConnectionPool $connectionPool,
        private LoggerInterface $logger,
    ) {}

    /**
     * @return array<int, array<string, mixed>>
     */
    public function findActiveItems(): array
    {
        $queryBuilder = $this->connectionPool->getQueryBuilderForTable('tx_myext_items');
        
        return $queryBuilder
            ->select('*')
            ->from('tx_myext_items')
            ->where(
                $queryBuilder->expr()->eq(
                    'active',
                    $queryBuilder->createNamedParameter(1, ParameterType::INTEGER),
                ),
            )
            ->executeQuery()
            ->fetchAllAssociative();
    }
}

<?php
// Configuration/Backend/Modules.php
return [
    'web_myextension' => [
        'parent' => 'content',
        'position' => ['after' => 'records'],
        'access' => 'user',
        'iconIdentifier' => 'myextension-module',
        'path' => '/module/content/myextension',
        'labels' => 'LLL:EXT:my_extension/Resources/Private/Language/locallang_mod.xlf',
        'extensionName' => 'MyExtension',
        'controllerActions' => [
            \Vendor\MyExtension\Controller\BackendController::class => [
                'index',
                'list',
            ],
        ],
    ],
];

// Resources/Public/JavaScript/MyModule.js
import Modal from '@typo3/backend/modal';
import Notification from '@typo3/backend/notification';
import Severity from '@typo3/backend/severity';

export default class MyModule {
    constructor() {
        this.initializeEventListeners();
    }

    initializeEventListeners() {
        document.querySelectorAll('[data-action="delete"]').forEach(element => {
            element.addEventListener('click', this.handleDelete.bind(this));
        });
    }

    handleDelete(event) {
        event.preventDefault();
        Modal.confirm(
            'Delete Item',
            'Are you sure?',
            Severity.warning,
            [
                { text: 'Cancel', trigger: (event, modal) => modal.hideModal() },
                {
                    text: 'Delete',
                    trigger: (event, modal) => {
                        this.performDelete();
                        modal.hideModal();
                    },
                    btnClass: 'btn-danger',
                }
            ]
        );
    }
}

# Configuration/Services.yaml
services:
  _defaults:
    autowire: true
    autoconfigure: true
    public: false

  Vendor\MyExtension\:
    resource: '../Classes/*'
    exclude:
      - '../Classes/Domain/Model/*'

  # Explicit public services if needed
  Vendor\MyExtension\Service\PublicApiService:
    public: true

<?php

declare(strict_types=1);

namespace Vendor\MyExtension\EventListener;

use TYPO3\CMS\Core\Attribute\AsEventListener;
use TYPO3\CMS\Core\DataHandling\Event\IsTableExcludedFromReferenceIndexEvent;

#[AsEventListener(identifier: 'myext/reference-index-example')]
final readonly class ReferenceIndexExampleListener
{
    public function __invoke(IsTableExcludedFromReferenceIndexEvent $event): void
    {
        if ($event->getTable() !== 'tx_myext_items') {
            return;
        }

        // Example: exclude a cache table from reference index (real Core event).
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
         bootstrap="vendor/typo3/testing-framework/Resources/Core/Build/UnitTestsBootstrap.php"
         colors="true">
    <testsuites>
        <testsuite name="Unit">
            <directory>Tests/Unit</directory>
        </testsuite>
        <testsuite name="Functional">
            <directory>Tests/Functional</directory>
        </testsuite>
    </testsuites>
    <coverage>
        <report>
            <clover outputFile="var/log/coverage.xml"/>
            <html outputDirectory="var/log/coverage"/>
        </report>
    </coverage>
    <source>
        <include>
            <directory>Classes</directory>
        </include>
    </source>
</phpunit>

<?php

declare(strict_types=1);

namespace Vendor\MyExtension\Tests\Architecture;

use PHPat\Selector\Selector;
use PHPat\Test\Builder\Rule;
use PHPat\Test\PHPat;

final class ArchitectureTest
{
    public function testDomainModelIndependence(): Rule
    {
        return PHPat::rule()
            ->classes(Selector::inNamespace('Vendor\MyExtension\Domain\Model'))
            ->shouldNot()
            ->dependOn()
            ->classes(Selector::inNamespace('Vendor\MyExtension\Controller'));
    }

    public function testServicesDoNotDependOnControllers(): Rule
    {
        return PHPat::rule()
            ->classes(Selector::inNamespace('Vendor\MyExtension\Service'))
            ->shouldNot()
            ->dependOn()
            ->classes(Selector::inNamespace('Vendor\MyExtension\Controller'));
    }
}

# .github/workflows/ci.yml
name: CI

on: [push, pull_request]

jobs:
  quality:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      
      - name: Setup PHP
        uses: shivammathur/setup-php@v2
        with:
          php-version: '8.3'
          
      - name: Install dependencies
        run: composer install
        
      - name: PHPStan
        run: vendor/bin/phpstan analyse --level=10
        
      - name: PHP-CS-Fixer
        run: vendor/bin/php-cs-fixer fix --dry-run --diff
        
      - name: PHPUnit
        run: vendor/bin/phpunit --coverage-clover var/log/coverage.xml

# phpstan.neon
includes:
    - vendor/phpstan/phpstan-strict-rules/rules.neon
    - vendor/saschaegerer/phpstan-typo3/extension.neon

parameters:
    level: 10
    paths:
        - Classes
        - Tests
    excludePaths:
        - Tests/Fixtures/*