diff --git a/src/Application.php b/src/Application.php
index b4fa578..cdec268 100644
--- a/src/Application.php
+++ b/src/Application.php
@@ -11,6 +11,8 @@
 
 namespace Enabel\CodingStandard;
 
+use Enabel\CodingStandard\Command\CiAddCommand;
+use Enabel\CodingStandard\Command\CiUpdateCommand;
 use Enabel\CodingStandard\Command\InitCommand;
 use Symfony\Component\Console\Application as BaseApplication;
 
@@ -24,6 +26,8 @@ public function __construct()
         parent::__construct(self::NAME, self::VERSION);
 
         $this->addCommand(new InitCommand());
+        $this->addCommand(new CiUpdateCommand());
+        $this->addCommand(new CiAddCommand());
         $this->setDefaultCommand('init');
     }
 }
diff --git a/src/Command/CiAddCommand.php b/src/Command/CiAddCommand.php
new file mode 100644
index 0000000..a68c455
--- /dev/null
+++ b/src/Command/CiAddCommand.php
@@ -0,0 +1,106 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the Enabel Coding Standard.
+ * Copyright (c) Enabel <https://github.com/Enabel>
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Enabel\CodingStandard\Command;
+
+use Enabel\CodingStandard\Detector\ProjectDetector;
+use Symfony\Component\Console\Attribute\AsCommand;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
+use Symfony\Component\Filesystem\Filesystem;
+
+#[AsCommand(
+    name: 'ci:add',
+    description: 'Add CI configuration for a new provider',
+)]
+final class CiAddCommand extends Command
+{
+    private const array VALID_PROVIDERS = ['gitlab', 'github', 'azure'];
+
+    protected function configure(): void
+    {
+        CiCommandHelper::addCiOptions($this);
+
+        $this
+            ->addOption('provider', null, InputOption::VALUE_REQUIRED, 'CI provider (gitlab, github, azure)')
+            ->addOption('force', 'f', InputOption::VALUE_NONE, 'Overwrite if provider already exists');
+    }
+
+    protected function execute(InputInterface $input, OutputInterface $output): int
+    {
+        $io = new SymfonyStyle($input, $output);
+        $filesystem = new Filesystem();
+
+        $outputDir = $input->getOption('output-dir');
+        if (!\is_string($outputDir)) {
+            $outputDir = '.';
+        }
+        $outputDir = realpath($outputDir) ?: $outputDir;
+
+        $provider = $input->getOption('provider');
+
+        if (!\is_string($provider) || '' === $provider) {
+            if ($input->isInteractive()) {
+                /** @var string $provider */
+                $provider = $io->choice('Which CI provider?', self::VALID_PROVIDERS);
+            } else {
+                $io->error('The --provider option is required in non-interactive mode.');
+
+                return Command::FAILURE;
+            }
+        }
+
+        if (!\in_array($provider, self::VALID_PROVIDERS, true)) {
+            $io->error(sprintf('Invalid provider "%s". Valid providers: %s', (string) $provider, implode(', ', self::VALID_PROVIDERS)));
+
+            return Command::FAILURE;
+        }
+
+        $detector = new ProjectDetector($outputDir);
+        $existingProviders = $detector->detectCiProviders();
+        $force = (bool) $input->getOption('force');
+
+        if (\in_array($provider, $existingProviders, true) && !$force) {
+            $io->error(sprintf('CI configuration for "%s" already exists. Use --force to overwrite.', $provider));
+
+            return Command::FAILURE;
+        }
+
+        $helper = new CiCommandHelper();
+        $files = $helper->generateCiFiles($input, $outputDir, $detector, [$provider]);
+
+        $writtenCount = 0;
+        foreach ($files as $relativePath => $content) {
+            $fullPath = $outputDir . '/' . $relativePath;
+            $directory = \dirname($fullPath);
+
+            if (!is_dir($directory)) {
+                $filesystem->mkdir($directory);
+            }
+
+            $filesystem->dumpFile($fullPath, $content);
+            $io->writeln(sprintf('  <info>Created:</info> %s', $relativePath));
+            ++$writtenCount;
+        }
+
+        $io->newLine();
+        $io->success(sprintf(
+            'CI configuration for %s added. %d files written.',
+            $provider,
+            $writtenCount,
+        ));
+
+        return Command::SUCCESS;
+    }
+}
diff --git a/src/Command/CiCommandHelper.php b/src/Command/CiCommandHelper.php
new file mode 100644
index 0000000..2523918
--- /dev/null
+++ b/src/Command/CiCommandHelper.php
@@ -0,0 +1,153 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the Enabel Coding Standard.
+ * Copyright (c) Enabel <https://github.com/Enabel>
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Enabel\CodingStandard\Command;
+
+use Enabel\CodingStandard\Config\Configuration;
+use Enabel\CodingStandard\Config\ConflictResolution;
+use Enabel\CodingStandard\Detector\ProjectDetector;
+use Enabel\CodingStandard\Generator\AzureDevOpsGenerator;
+use Enabel\CodingStandard\Generator\GeneratorInterface;
+use Enabel\CodingStandard\Generator\GitHubActionsGenerator;
+use Enabel\CodingStandard\Generator\GitLabCiGenerator;
+use Enabel\CodingStandard\Template\TemplateRenderer;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+
+final class CiCommandHelper
+{
+    public static function addCiOptions(Command $command): void
+    {
+        $command
+            ->addOption('php-version', null, InputOption::VALUE_REQUIRED, 'PHP version (8.3, 8.4, 8.5)')
+            ->addOption('symfony', null, InputOption::VALUE_REQUIRED, 'Symfony version (7.4, 8.0) or "no"')
+            ->addOption('database', null, InputOption::VALUE_REQUIRED, 'Database type (mariadb, mysql, postgresql)')
+            ->addOption('database-version', null, InputOption::VALUE_REQUIRED, 'Database version')
+            ->addOption('php-cs-fixer', null, InputOption::VALUE_NEGATABLE, 'Include PHP-CS-Fixer')
+            ->addOption('phpstan', null, InputOption::VALUE_NEGATABLE, 'Include PHPStan')
+            ->addOption('rector', null, InputOption::VALUE_NEGATABLE, 'Include Rector')
+            ->addOption('output-dir', 'o', InputOption::VALUE_REQUIRED, 'Output directory', '.');
+    }
+
+    public function buildConfiguration(InputInterface $input, string $outputDir, ProjectDetector $detector, string $ciProvider): Configuration
+    {
+        $projectName = $detector->getProjectName() ?? basename($outputDir);
+
+        $phpVersion = $this->resolveOption($input, 'php-version') ?? $detector->getPhpVersion() ?? '8.4';
+
+        $symfony = $this->resolveOption($input, 'symfony');
+        if (null === $symfony) {
+            $isSymfony = $detector->isSymfonyProject();
+            $symfonyVersion = $isSymfony ? ($detector->getSymfonyVersion() ?? '8.0') : null;
+        } else {
+            $isSymfony = 'no' !== $symfony;
+            $symfonyVersion = $isSymfony ? $symfony : null;
+        }
+
+        $databaseType = $this->resolveOption($input, 'database');
+        $databaseVersion = $this->resolveOption($input, 'database-version');
+
+        if (null === $databaseType) {
+            $dbInfo = $detector->detectDatabase();
+            if (null !== $dbInfo) {
+                $databaseType = $dbInfo['type'];
+                $databaseVersion ??= $dbInfo['version'];
+            }
+        }
+
+        $includePhpCsFixer = $this->resolveNegatableOption($input, 'php-cs-fixer') ?? $detector->hasPhpCsFixer();
+        $includePhpStan = $this->resolveNegatableOption($input, 'phpstan') ?? $detector->hasPhpStan();
+        $includeRector = $this->resolveNegatableOption($input, 'rector') ?? $detector->hasRector();
+
+        return new Configuration(
+            projectName: $projectName,
+            phpVersion: $phpVersion,
+            phpstanLevel: 9,
+            isSymfonyProject: $isSymfony,
+            symfonyVersion: $symfonyVersion,
+            ciProvider: $ciProvider,
+            devEnvironment: 'local',
+            includeMakefile: false,
+            includePhpCsFixer: $includePhpCsFixer,
+            includePhpStan: $includePhpStan,
+            includeRector: $includeRector,
+            includePhpUnit: $detector->hasPhpUnit(),
+            srcPath: 'src',
+            testsPath: 'tests',
+            outputDir: $outputDir,
+            conflictResolution: ConflictResolution::REPLACE,
+            databaseType: $databaseType,
+            databaseVersion: $databaseVersion,
+        );
+    }
+
+    /**
+     * @param list<string> $providers
+     *
+     * @return array<string, string> Map of relative file paths to content
+     */
+    public function generateCiFiles(InputInterface $input, string $outputDir, ProjectDetector $detector, array $providers): array
+    {
+        $templateRenderer = new TemplateRenderer($this->getTemplatesPath());
+        $generators = $this->createCiGenerators($templateRenderer);
+        $files = [];
+
+        foreach ($providers as $provider) {
+            $config = $this->buildConfiguration($input, $outputDir, $detector, $provider);
+
+            foreach ($generators as $generator) {
+                if ($generator->supports($config)) {
+                    $files = array_merge($files, $generator->generate($config));
+                }
+            }
+        }
+
+        return $files;
+    }
+
+    /**
+     * @return list<GeneratorInterface>
+     */
+    private function createCiGenerators(TemplateRenderer $renderer): array
+    {
+        return [
+            new GitLabCiGenerator($renderer),
+            new GitHubActionsGenerator($renderer),
+            new AzureDevOpsGenerator($renderer),
+        ];
+    }
+
+    private function getTemplatesPath(): string
+    {
+        return dirname(__DIR__, 2) . '/templates';
+    }
+
+    private function resolveOption(InputInterface $input, string $name): ?string
+    {
+        if (!$input->hasParameterOption('--' . $name)) {
+            return null;
+        }
+
+        $value = $input->getOption($name);
+
+        return \is_string($value) && '' !== $value ? $value : null;
+    }
+
+    private function resolveNegatableOption(InputInterface $input, string $name): ?bool
+    {
+        if (!$input->hasParameterOption('--' . $name) && !$input->hasParameterOption('--no-' . $name)) {
+            return null;
+        }
+
+        return (bool) $input->getOption($name);
+    }
+}
diff --git a/src/Command/CiUpdateCommand.php b/src/Command/CiUpdateCommand.php
new file mode 100644
index 0000000..6a272e1
--- /dev/null
+++ b/src/Command/CiUpdateCommand.php
@@ -0,0 +1,79 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the Enabel Coding Standard.
+ * Copyright (c) Enabel <https://github.com/Enabel>
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Enabel\CodingStandard\Command;
+
+use Enabel\CodingStandard\Detector\ProjectDetector;
+use Symfony\Component\Console\Attribute\AsCommand;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
+use Symfony\Component\Filesystem\Filesystem;
+
+#[AsCommand(
+    name: 'ci:update',
+    description: 'Update existing CI configuration',
+)]
+final class CiUpdateCommand extends Command
+{
+    protected function configure(): void
+    {
+        CiCommandHelper::addCiOptions($this);
+    }
+
+    protected function execute(InputInterface $input, OutputInterface $output): int
+    {
+        $io = new SymfonyStyle($input, $output);
+        $filesystem = new Filesystem();
+
+        $outputDir = $input->getOption('output-dir');
+        if (!\is_string($outputDir)) {
+            $outputDir = '.';
+        }
+        $outputDir = realpath($outputDir) ?: $outputDir;
+
+        $detector = new ProjectDetector($outputDir);
+        $providers = $detector->detectCiProviders();
+
+        if ([] === $providers) {
+            $io->error('No existing CI configuration detected. Use ci:add to add a new CI provider.');
+
+            return Command::FAILURE;
+        }
+
+        $helper = new CiCommandHelper();
+        $files = $helper->generateCiFiles($input, $outputDir, $detector, $providers);
+
+        $writtenCount = 0;
+        foreach ($files as $relativePath => $content) {
+            $fullPath = $outputDir . '/' . $relativePath;
+            $directory = \dirname($fullPath);
+
+            if (!is_dir($directory)) {
+                $filesystem->mkdir($directory);
+            }
+
+            $filesystem->dumpFile($fullPath, $content);
+            $io->writeln(sprintf('  <info>Updated:</info> %s', $relativePath));
+            ++$writtenCount;
+        }
+
+        $io->newLine();
+        $io->success(sprintf(
+            'CI configuration updated for %s. %d files written.',
+            implode(', ', $providers),
+            $writtenCount,
+        ));
+
+        return Command::SUCCESS;
+    }
+}
diff --git a/src/Detector/ProjectDetector.php b/src/Detector/ProjectDetector.php
index c412b33..3b4341f 100644
--- a/src/Detector/ProjectDetector.php
+++ b/src/Detector/ProjectDetector.php
@@ -13,11 +13,83 @@
 
 final readonly class ProjectDetector
 {
+    private const array CI_PROVIDER_FILES = [
+        'gitlab' => '.gitlab-ci.yml',
+        'github' => '.github/workflows/ci.yml',
+        'azure' => 'azure-pipelines.yml',
+    ];
+
     public function __construct(
         private string $projectDir,
     ) {
     }
 
+    /**
+     * @return list<string> CI providers detected ('gitlab', 'github', 'azure')
+     */
+    public function detectCiProviders(): array
+    {
+        $providers = [];
+
+        foreach (self::CI_PROVIDER_FILES as $provider => $file) {
+            if (file_exists($this->projectDir . '/' . $file)) {
+                $providers[] = $provider;
+            }
+        }
+
+        return $providers;
+    }
+
+    /**
+     * @return array{type: string, version: string}|null
+     */
+    public function detectDatabase(): ?array
+    {
+        $composePath = $this->projectDir . '/compose.yaml';
+        if (!file_exists($composePath)) {
+            return null;
+        }
+
+        $content = file_get_contents($composePath);
+        if (false === $content) {
+            return null;
+        }
+
+        $patterns = [
+            'mariadb' => '/image:\s*mariadb:(\d+\.\d+)/',
+            'mysql' => '/image:\s*mysql:(\d+\.\d+)/',
+            'postgresql' => '/image:\s*postgres:(\d+)/',
+        ];
+
+        foreach ($patterns as $type => $pattern) {
+            if (preg_match($pattern, $content, $matches)) {
+                return ['type' => $type, 'version' => $matches[1]];
+            }
+        }
+
+        return null;
+    }
+
+    public function hasPhpCsFixer(): bool
+    {
+        return file_exists($this->projectDir . '/.php-cs-fixer.dist.php');
+    }
+
+    public function hasPhpStan(): bool
+    {
+        return file_exists($this->projectDir . '/phpstan.neon');
+    }
+
+    public function hasRector(): bool
+    {
+        return file_exists($this->projectDir . '/rector.php');
+    }
+
+    public function hasPhpUnit(): bool
+    {
+        return file_exists($this->projectDir . '/phpunit.dist.xml');
+    }
+
     public function getProjectName(): ?string
     {
         $composerJson = $this->readComposerJson();
diff --git a/src/Generator/GitHubActionsGenerator.php b/src/Generator/GitHubActionsGenerator.php
index 683eb7f..815d473 100644
--- a/src/Generator/GitHubActionsGenerator.php
+++ b/src/Generator/GitHubActionsGenerator.php
@@ -17,21 +17,24 @@ final class GitHubActionsGenerator extends AbstractGenerator
 {
     public function generate(Configuration $config): array
     {
+        $variables = [
+            'phpVersion' => $config->phpVersion,
+            'isSymfony' => $config->isSymfonyProject,
+            'includePhpCsFixer' => $config->includePhpCsFixer,
+            'includePhpStan' => $config->includePhpStan,
+            'includeRector' => $config->includeRector,
+            'hasDatabase' => $config->hasDatabase(),
+            'databaseType' => $config->databaseType,
+            'databaseImage' => $config->getDatabaseImage(),
+            'databasePort' => $config->getDatabasePort(),
+            'databaseUrl' => $config->getDatabaseUrl(),
+            'databaseEnvVars' => $config->getDatabaseEnvVars(),
+            'phpDatabaseExtension' => $config->getPhpDatabaseExtension(),
+        ];
+
         return [
-            '.github/workflows/ci.yml' => $this->render('ci/github/workflows/ci.yml.tpl', [
-                'phpVersion' => $config->phpVersion,
-                'isSymfony' => $config->isSymfonyProject,
-                'includePhpCsFixer' => $config->includePhpCsFixer,
-                'includePhpStan' => $config->includePhpStan,
-                'includeRector' => $config->includeRector,
-                'hasDatabase' => $config->hasDatabase(),
-                'databaseType' => $config->databaseType,
-                'databaseImage' => $config->getDatabaseImage(),
-                'databasePort' => $config->getDatabasePort(),
-                'databaseUrl' => $config->getDatabaseUrl(),
-                'databaseEnvVars' => $config->getDatabaseEnvVars(),
-                'phpDatabaseExtension' => $config->getPhpDatabaseExtension(),
-            ]),
+            '.github/workflows/ci.yml' => $this->render('ci/github/workflows/ci.yml.tpl', $variables),
+            '.github/ci/Dockerfile' => $this->render('ci/Dockerfile.tpl', $variables),
         ];
     }
 
@@ -42,6 +45,6 @@ public function supports(Configuration $config): bool
 
     public function getTargetFiles(): array
     {
-        return ['.github/workflows/ci.yml'];
+        return ['.github/workflows/ci.yml', '.github/ci/Dockerfile'];
     }
 }
diff --git a/src/Generator/GitLabCiGenerator.php b/src/Generator/GitLabCiGenerator.php
index 7c0fa71..6cc8e61 100644
--- a/src/Generator/GitLabCiGenerator.php
+++ b/src/Generator/GitLabCiGenerator.php
@@ -17,21 +17,24 @@ final class GitLabCiGenerator extends AbstractGenerator
 {
     public function generate(Configuration $config): array
     {
+        $variables = [
+            'phpVersion' => $config->phpVersion,
+            'isSymfony' => $config->isSymfonyProject,
+            'includePhpCsFixer' => $config->includePhpCsFixer,
+            'includePhpStan' => $config->includePhpStan,
+            'includeRector' => $config->includeRector,
+            'hasDatabase' => $config->hasDatabase(),
+            'databaseType' => $config->databaseType,
+            'databaseImage' => $config->getDatabaseImage(),
+            'databasePort' => $config->getDatabasePort(),
+            'databaseUrl' => $config->getDatabaseUrl(),
+            'databaseEnvVars' => $config->getDatabaseEnvVars(),
+            'phpDatabaseExtension' => $config->getPhpDatabaseExtension(),
+        ];
+
         return [
-            '.gitlab-ci.yml' => $this->render('ci/gitlab-ci.yml.tpl', [
-                'phpVersion' => $config->phpVersion,
-                'isSymfony' => $config->isSymfonyProject,
-                'includePhpCsFixer' => $config->includePhpCsFixer,
-                'includePhpStan' => $config->includePhpStan,
-                'includeRector' => $config->includeRector,
-                'hasDatabase' => $config->hasDatabase(),
-                'databaseType' => $config->databaseType,
-                'databaseImage' => $config->getDatabaseImage(),
-                'databasePort' => $config->getDatabasePort(),
-                'databaseUrl' => $config->getDatabaseUrl(),
-                'databaseEnvVars' => $config->getDatabaseEnvVars(),
-                'phpDatabaseExtension' => $config->getPhpDatabaseExtension(),
-            ]),
+            '.gitlab-ci.yml' => $this->render('ci/gitlab-ci.yml.tpl', $variables),
+            '.gitlab/ci/Dockerfile' => $this->render('ci/Dockerfile.tpl', $variables),
         ];
     }
 
@@ -42,6 +45,6 @@ public function supports(Configuration $config): bool
 
     public function getTargetFiles(): array
     {
-        return ['.gitlab-ci.yml'];
+        return ['.gitlab-ci.yml', '.gitlab/ci/Dockerfile'];
     }
 }
diff --git a/templates/ci/Dockerfile.tpl b/templates/ci/Dockerfile.tpl
new file mode 100644
index 0000000..d1b30d3
--- /dev/null
+++ b/templates/ci/Dockerfile.tpl
@@ -0,0 +1,23 @@
+FROM php:<?= $phpVersion ?>-cli
+
+RUN apt-get update && apt-get install -y \
+        git \
+        unzip \
+        libicu-dev \
+        libzip-dev \
+<?php if ($hasDatabase && $databaseType === 'postgresql'): ?>
+        libpq-dev \
+<?php endif; ?>
+    && docker-php-ext-install \
+        intl \
+        zip \
+<?php if ($hasDatabase): ?>
+        pdo \
+        <?= $phpDatabaseExtension === 'pgsql' ? 'pdo_pgsql' : 'pdo_mysql' ?> \
+<?php endif; ?>
+    && pecl install pcov \
+    && docker-php-ext-enable pcov \
+    && apt-get clean \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY --from=composer:latest /usr/bin/composer /usr/bin/composer
diff --git a/templates/ci/github/workflows/ci.yml.tpl b/templates/ci/github/workflows/ci.yml.tpl
index 49d282a..f48673e 100644
--- a/templates/ci/github/workflows/ci.yml.tpl
+++ b/templates/ci/github/workflows/ci.yml.tpl
@@ -6,19 +6,50 @@ on:
   pull_request:
     branches: [main, master]
 
+permissions:
+  contents: read
+  packages: write
+
+env:
+  CI_IMAGE: ghcr.io/${{ github.repository }}/ci:php<?= $phpVersion ?>
+
+
 jobs:
-  build:
+  build-image:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
 
-      - name: Setup PHP
-        uses: shivammathur/setup-php@v2
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
         with:
-          php-version: '<?= $phpVersion ?>'
-          extensions: intl, zip<?php if ($hasDatabase): ?>, pdo, pdo_<?= $phpDatabaseExtension ?><?php endif; ?>
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
 
-          coverage: pcov
+      - name: Build and push CI image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: .github/ci/Dockerfile
+          push: true
+          tags: ${{ env.CI_IMAGE }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+
+  build:
+    needs: [build-image]
+    runs-on: ubuntu-latest
+    container:
+      image: ${{ env.CI_IMAGE }}
+      credentials:
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+    steps:
+      - uses: actions/checkout@v4
 
       - name: Get Composer cache directory
         id: composer-cache
@@ -61,17 +92,16 @@ jobs:
 
 <?php if ($isSymfony): ?>
   lint:
-    needs: build
+    needs: [build-image, build]
     runs-on: ubuntu-latest
+    container:
+      image: ${{ env.CI_IMAGE }}
+      credentials:
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
     steps:
       - uses: actions/checkout@v4
 
-      - name: Setup PHP
-        uses: shivammathur/setup-php@v2
-        with:
-          php-version: '<?= $phpVersion ?>'
-          extensions: intl, zip
-
       - name: Install dependencies
         run: composer install --prefer-dist --no-progress
 
@@ -89,17 +119,16 @@ jobs:
 
 <?php endif; ?>
   analyze:
-    needs: build
+    needs: [build-image, build]
     runs-on: ubuntu-latest
+    container:
+      image: ${{ env.CI_IMAGE }}
+      credentials:
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
     steps:
       - uses: actions/checkout@v4
 
-      - name: Setup PHP
-        uses: shivammathur/setup-php@v2
-        with:
-          php-version: '<?= $phpVersion ?>'
-          extensions: intl, zip
-
       - name: Install dependencies
         run: composer install --prefer-dist --no-progress
 
@@ -120,7 +149,7 @@ jobs:
 
 <?php endif; ?>
   test:
-    needs: build
+    needs: [build-image, build]
     runs-on: ubuntu-latest
 <?php if ($hasDatabase): ?>
     services:
@@ -132,26 +161,20 @@ jobs:
           <?= $key ?>: <?= $value ?>
 
 <?php endforeach; ?>
-        ports:
-          - <?= $databasePort ?>:<?= $databasePort ?>
-
 <?php if ($databaseType === 'postgresql'): ?>
         options: --health-cmd pg_isready --health-interval=10s --health-timeout=5s --health-retries=3
 <?php else: ?>
         options: --health-cmd="healthcheck.sh --connect --innodb_initialized" --health-interval=10s --health-timeout=5s --health-retries=3
 <?php endif; ?>
 <?php endif; ?>
+    container:
+      image: ${{ env.CI_IMAGE }}
+      credentials:
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
     steps:
       - uses: actions/checkout@v4
 
-      - name: Setup PHP
-        uses: shivammathur/setup-php@v2
-        with:
-          php-version: '<?= $phpVersion ?>'
-          extensions: intl, zip<?php if ($hasDatabase): ?>, pdo, pdo_<?= $phpDatabaseExtension ?><?php endif; ?>
-
-          coverage: pcov
-
       - name: Install dependencies
         run: composer install --prefer-dist --no-progress
 
@@ -164,19 +187,17 @@ jobs:
       - name: Create database
         run: bin/console doctrine:database:create --if-not-exists --env=test
         env:
-          DATABASE_URL: <?= $databaseUrl ?>
-
+          DATABASE_URL: "<?= str_replace('127.0.0.1', 'database', $databaseUrl) ?>"
 
       - name: Run migrations
         run: bin/console doctrine:migrations:migrate --no-interaction --allow-no-migration --env=test
         env:
-          DATABASE_URL: <?= $databaseUrl ?>
-
+          DATABASE_URL: "<?= str_replace('127.0.0.1', 'database', $databaseUrl) ?>"
 
 <?php endif; ?>
       - name: Run tests
         run: bin/phpunit --testdox
 <?php if ($hasDatabase): ?>
         env:
-          DATABASE_URL: <?= $databaseUrl ?>
+          DATABASE_URL: "<?= str_replace('127.0.0.1', 'database', $databaseUrl) ?>"
 <?php endif; ?>
diff --git a/templates/ci/gitlab-ci.yml.tpl b/templates/ci/gitlab-ci.yml.tpl
index f9dc6d2..137b9a6 100644
--- a/templates/ci/gitlab-ci.yml.tpl
+++ b/templates/ci/gitlab-ci.yml.tpl
@@ -1,4 +1,5 @@
 stages:
+  - .pre
   - build
   - lint
   - analyze
@@ -13,9 +14,11 @@ variables:
   COMPOSER_ALLOW_SUPERUSER: 1
   COMPOSER_NO_INTERACTION: 1
   SECRET_DETECTION_ENABLED: 'true'
+  CI_IMAGE: $CI_REGISTRY_IMAGE/ci:php<?= $phpVersion ?>
 
-.php-image: &php-image
-  image: php:<?= $phpVersion ?>-cli
+
+.ci-image: &ci-image
+  image: $CI_IMAGE
 
 .composer-cache: &composer-cache
   cache:
@@ -33,20 +36,40 @@ variables:
 <?php endif; ?>
     policy: pull
 
+# ====================
+# Pre Stage — Build CI Image
+# ====================
+
+build:image:
+  stage: .pre
+  image:
+    name: gcr.io/kaniko-project/executor:v1.23.2-debug
+    entrypoint: [""]
+  script:
+    - mkdir -p /kaniko/.docker
+    - echo "{\"auths\":{\"$CI_REGISTRY\":{\"auth\":\"$(printf '%s:%s' "$CI_REGISTRY_USER" "$CI_REGISTRY_PASSWORD" | base64)\"}}}" > /kaniko/.docker/config.json
+    - >-
+      /kaniko/executor
+      --context $CI_PROJECT_DIR
+      --dockerfile $CI_PROJECT_DIR/.gitlab/ci/Dockerfile
+      --destination $CI_IMAGE
+      --cache=true
+      --cache-repo $CI_REGISTRY_IMAGE/ci/cache
+  rules:
+    - changes:
+        - .gitlab/ci/Dockerfile
+    - if: $BUILD_CI_IMAGE == "true"
+    - when: manual
+      allow_failure: true
+
 # ====================
 # Build Stage
 # ====================
 
 build:
-  <<: *php-image
+  <<: *ci-image
   stage: build
-  before_script:
-    - apt-get update && apt-get install -y git unzip libicu-dev libzip-dev<?php if ($hasDatabase && $databaseType === 'postgresql'): ?> libpq-dev<?php endif; ?>
-
-    - docker-php-ext-install intl zip<?php if ($hasDatabase): ?> pdo <?= $databaseType === 'postgresql' ? 'pdo_pgsql' : 'pdo_mysql' ?><?php endif; ?>
-
-    - pecl install pcov && docker-php-ext-enable pcov
-    - curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer
+  needs: [build:image]
   script:
     - composer validate --no-check-publish
     - composer install --prefer-dist --no-progress
@@ -80,46 +103,34 @@ build:
 # ====================
 
 lint:yaml:
-  <<: *php-image
+  <<: *ci-image
   <<: *composer-cache
   stage: lint
-  needs: [build]
-  before_script:
-    - apt-get update && apt-get install -y libicu-dev libzip-dev
-    - docker-php-ext-install intl zip
+  needs: [build:image, build]
   script:
     - bin/console lint:yaml config --parse-tags
 
 lint:twig:
-  <<: *php-image
+  <<: *ci-image
   <<: *composer-cache
   stage: lint
-  needs: [build]
-  before_script:
-    - apt-get update && apt-get install -y libicu-dev libzip-dev
-    - docker-php-ext-install intl zip
+  needs: [build:image, build]
   script:
     - bin/console lint:twig templates
 
 lint:container:
-  <<: *php-image
+  <<: *ci-image
   <<: *composer-cache
   stage: lint
-  needs: [build]
-  before_script:
-    - apt-get update && apt-get install -y libicu-dev libzip-dev
-    - docker-php-ext-install intl zip
+  needs: [build:image, build]
   script:
     - bin/console lint:container
 
 lint:composer:
-  <<: *php-image
+  <<: *ci-image
   <<: *composer-cache
   stage: lint
-  needs: [build]
-  before_script:
-    - apt-get update && apt-get install -y git unzip
-    - curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer
+  needs: [build:image, build]
   script:
     - composer validate --no-check-publish
 
@@ -130,23 +141,20 @@ lint:composer:
 
 <?php if ($includePhpCsFixer): ?>
 php-cs-fixer:
-  <<: *php-image
+  <<: *ci-image
   <<: *composer-cache
   stage: analyze
-  needs: [build]
+  needs: [build:image, build]
   script:
     - tools/php-cs-fixer/vendor/bin/php-cs-fixer fix --dry-run --diff
 
 <?php endif; ?>
 <?php if ($includePhpStan): ?>
 phpstan:
-  <<: *php-image
+  <<: *ci-image
   <<: *composer-cache
   stage: analyze
-  needs: [build]
-  before_script:
-    - apt-get update && apt-get install -y libicu-dev libzip-dev
-    - docker-php-ext-install intl zip
+  needs: [build:image, build]
   script:
     - tools/phpstan/vendor/bin/phpstan analyse
 
@@ -156,9 +164,9 @@ phpstan:
 # ====================
 
 phpunit:
-  <<: *php-image
+  <<: *ci-image
   stage: test
-  needs: [build]
+  needs: [build:image, build]
 <?php if ($hasDatabase): ?>
   services:
     - name: <?= $databaseImage ?>
@@ -172,14 +180,7 @@ phpunit:
   variables:
     APP_ENV: test
     DATABASE_URL: "<?= str_replace('127.0.0.1', 'database', $databaseUrl) ?>"
-<?php endif; ?>
   before_script:
-    - apt-get update && apt-get install -y git unzip libicu-dev libzip-dev<?php if ($hasDatabase && $databaseType === 'postgresql'): ?> libpq-dev<?php endif; ?>
-
-    - docker-php-ext-install intl zip<?php if ($hasDatabase): ?> pdo <?= $databaseType === 'postgresql' ? 'pdo_pgsql' : 'pdo_mysql' ?><?php endif; ?>
-
-    - pecl install pcov && docker-php-ext-enable pcov
-<?php if ($hasDatabase): ?>
     # Wait for database to be ready
     - |
       for i in $(seq 1 30); do
diff --git a/tests/Command/CiAddCommandTest.php b/tests/Command/CiAddCommandTest.php
new file mode 100644
index 0000000..6f91665
--- /dev/null
+++ b/tests/Command/CiAddCommandTest.php
@@ -0,0 +1,141 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the Enabel Coding Standard.
+ * Copyright (c) Enabel <https://github.com/Enabel>
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Enabel\CodingStandard\Tests\Command;
+
+use Enabel\CodingStandard\Command\CiAddCommand;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Tester\CommandTester;
+use Symfony\Component\Filesystem\Filesystem;
+
+final class CiAddCommandTest extends TestCase
+{
+    private string $tempDir;
+    private Filesystem $filesystem;
+
+    protected function setUp(): void
+    {
+        $this->filesystem = new Filesystem();
+        $this->tempDir = sys_get_temp_dir() . '/ci-add-command-test-' . uniqid();
+        mkdir($this->tempDir);
+
+        $this->writeComposerJson([
+            'name' => 'enabel/test-project',
+            'require' => ['php' => '>=8.4'],
+        ]);
+
+        file_put_contents($this->tempDir . '/.php-cs-fixer.dist.php', '<?php return [];');
+        file_put_contents($this->tempDir . '/phpstan.neon', 'parameters:');
+    }
+
+    protected function tearDown(): void
+    {
+        $this->filesystem->remove($this->tempDir);
+    }
+
+    public function testMissingProviderInNonInteractiveModeReturnFailure(): void
+    {
+        $tester = $this->createCommandTester();
+
+        $tester->execute(['--output-dir' => $this->tempDir], ['interactive' => false]);
+
+        self::assertSame(Command::FAILURE, $tester->getStatusCode());
+        self::assertStringContainsString('--provider option is required', $tester->getDisplay());
+    }
+
+    public function testProviderAlreadyExistsReturnFailure(): void
+    {
+        file_put_contents($this->tempDir . '/.gitlab-ci.yml', 'stages: [test]');
+
+        $tester = $this->createCommandTester();
+
+        $tester->execute(['--provider' => 'gitlab', '--output-dir' => $this->tempDir], ['interactive' => false]);
+
+        self::assertSame(Command::FAILURE, $tester->getStatusCode());
+        self::assertStringContainsString('already exists', $tester->getDisplay());
+    }
+
+    public function testForceOverwritesExistingProvider(): void
+    {
+        file_put_contents($this->tempDir . '/.gitlab-ci.yml', 'stages: [test]');
+
+        $tester = $this->createCommandTester();
+
+        $tester->execute(
+            ['--provider' => 'gitlab', '--force' => true, '--output-dir' => $this->tempDir],
+            ['interactive' => false],
+        );
+
+        self::assertSame(Command::SUCCESS, $tester->getStatusCode());
+        self::assertFileExists($this->tempDir . '/.gitlab-ci.yml');
+    }
+
+    public function testGeneratesGitHubFiles(): void
+    {
+        $tester = $this->createCommandTester();
+
+        $tester->execute(['--provider' => 'github', '--output-dir' => $this->tempDir], ['interactive' => false]);
+
+        self::assertSame(Command::SUCCESS, $tester->getStatusCode());
+        self::assertFileExists($this->tempDir . '/.github/workflows/ci.yml');
+        self::assertFileExists($this->tempDir . '/.github/ci/Dockerfile');
+
+        $ci = (string) file_get_contents($this->tempDir . '/.github/workflows/ci.yml');
+        self::assertStringContainsString('name:', $ci);
+
+        $dockerfile = (string) file_get_contents($this->tempDir . '/.github/ci/Dockerfile');
+        self::assertStringContainsString('php:8.4', $dockerfile);
+    }
+
+    public function testGeneratesGitLabFiles(): void
+    {
+        $tester = $this->createCommandTester();
+
+        $tester->execute(['--provider' => 'gitlab', '--output-dir' => $this->tempDir], ['interactive' => false]);
+
+        self::assertSame(Command::SUCCESS, $tester->getStatusCode());
+        self::assertFileExists($this->tempDir . '/.gitlab-ci.yml');
+        self::assertFileExists($this->tempDir . '/.gitlab/ci/Dockerfile');
+
+        $ci = (string) file_get_contents($this->tempDir . '/.gitlab-ci.yml');
+        self::assertStringContainsString('stages:', $ci);
+
+        $dockerfile = (string) file_get_contents($this->tempDir . '/.gitlab/ci/Dockerfile');
+        self::assertStringContainsString('php:8.4', $dockerfile);
+    }
+
+    public function testInvalidProviderReturnFailure(): void
+    {
+        $tester = $this->createCommandTester();
+
+        $tester->execute(['--provider' => 'jenkins', '--output-dir' => $this->tempDir], ['interactive' => false]);
+
+        self::assertSame(Command::FAILURE, $tester->getStatusCode());
+        self::assertStringContainsString('Invalid provider', $tester->getDisplay());
+    }
+
+    private function createCommandTester(): CommandTester
+    {
+        return new CommandTester(new CiAddCommand());
+    }
+
+    /**
+     * @param array<string, mixed> $data
+     */
+    private function writeComposerJson(array $data): void
+    {
+        file_put_contents(
+            $this->tempDir . '/composer.json',
+            json_encode($data, \JSON_PRETTY_PRINT | \JSON_UNESCAPED_SLASHES),
+        );
+    }
+}
diff --git a/tests/Command/CiUpdateCommandTest.php b/tests/Command/CiUpdateCommandTest.php
new file mode 100644
index 0000000..9bad909
--- /dev/null
+++ b/tests/Command/CiUpdateCommandTest.php
@@ -0,0 +1,143 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the Enabel Coding Standard.
+ * Copyright (c) Enabel <https://github.com/Enabel>
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Enabel\CodingStandard\Tests\Command;
+
+use Enabel\CodingStandard\Command\CiUpdateCommand;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Tester\CommandTester;
+use Symfony\Component\Filesystem\Filesystem;
+
+final class CiUpdateCommandTest extends TestCase
+{
+    private string $tempDir;
+    private Filesystem $filesystem;
+
+    protected function setUp(): void
+    {
+        $this->filesystem = new Filesystem();
+        $this->tempDir = sys_get_temp_dir() . '/ci-update-command-test-' . uniqid();
+        mkdir($this->tempDir);
+
+        // Simulate a PHP project with composer.json
+        $this->writeComposerJson([
+            'name' => 'enabel/test-project',
+            'require' => [
+                'php' => '>=8.4',
+                'symfony/framework-bundle' => '^7.4',
+            ],
+        ]);
+
+        // Simulate tool config files so they are detected
+        file_put_contents($this->tempDir . '/.php-cs-fixer.dist.php', '<?php return [];');
+        file_put_contents($this->tempDir . '/phpstan.neon', 'parameters:');
+    }
+
+    protected function tearDown(): void
+    {
+        $this->filesystem->remove($this->tempDir);
+    }
+
+    public function testFailsWhenNoCiDetected(): void
+    {
+        $tester = $this->executeCommand();
+
+        self::assertSame(Command::FAILURE, $tester->getStatusCode());
+        self::assertStringContainsString('No existing CI configuration', $tester->getDisplay());
+    }
+
+    public function testRegeneratesGitLabWhenGitLabCiExists(): void
+    {
+        file_put_contents($this->tempDir . '/.gitlab-ci.yml', 'stages: [test]');
+
+        $tester = $this->executeCommand();
+
+        self::assertSame(Command::SUCCESS, $tester->getStatusCode());
+        self::assertFileExists($this->tempDir . '/.gitlab-ci.yml');
+        self::assertFileExists($this->tempDir . '/.gitlab/ci/Dockerfile');
+    }
+
+    public function testRegeneratesBothWhenGitLabAndGitHubExist(): void
+    {
+        file_put_contents($this->tempDir . '/.gitlab-ci.yml', 'stages: [test]');
+        $this->filesystem->mkdir($this->tempDir . '/.github/workflows');
+        file_put_contents($this->tempDir . '/.github/workflows/ci.yml', 'name: CI');
+
+        $tester = $this->executeCommand();
+
+        self::assertSame(Command::SUCCESS, $tester->getStatusCode());
+
+        // GitLab files
+        self::assertFileExists($this->tempDir . '/.gitlab-ci.yml');
+        self::assertFileExists($this->tempDir . '/.gitlab/ci/Dockerfile');
+
+        // GitHub files
+        self::assertFileExists($this->tempDir . '/.github/workflows/ci.yml');
+        self::assertFileExists($this->tempDir . '/.github/ci/Dockerfile');
+    }
+
+    public function testOverridePhpVersionChangesDockerfile(): void
+    {
+        file_put_contents($this->tempDir . '/.gitlab-ci.yml', 'stages: [test]');
+
+        $tester = $this->executeCommand(['--php-version' => '8.5']);
+
+        self::assertSame(Command::SUCCESS, $tester->getStatusCode());
+
+        $dockerfile = (string) file_get_contents($this->tempDir . '/.gitlab/ci/Dockerfile');
+        self::assertStringContainsString('php:8.5-cli', $dockerfile);
+    }
+
+    public function testOverrideDatabaseAddsDbToCi(): void
+    {
+        file_put_contents($this->tempDir . '/.gitlab-ci.yml', 'stages: [test]');
+
+        $tester = $this->executeCommand([
+            '--database' => 'mariadb',
+            '--database-version' => '11.4',
+        ]);
+
+        self::assertSame(Command::SUCCESS, $tester->getStatusCode());
+
+        $dockerfile = (string) file_get_contents($this->tempDir . '/.gitlab/ci/Dockerfile');
+        self::assertStringContainsString('pdo_mysql', $dockerfile);
+
+        $ciYml = (string) file_get_contents($this->tempDir . '/.gitlab-ci.yml');
+        self::assertStringContainsString('mariadb', $ciYml);
+    }
+
+    /**
+     * @param array<string, string> $input
+     */
+    private function executeCommand(array $input = []): CommandTester
+    {
+        $command = new CiUpdateCommand();
+        $tester = new CommandTester($command);
+        $tester->execute(
+            array_merge(['--output-dir' => $this->tempDir], $input),
+            ['interactive' => false],
+        );
+
+        return $tester;
+    }
+
+    /**
+     * @param array<string, mixed> $data
+     */
+    private function writeComposerJson(array $data): void
+    {
+        file_put_contents(
+            $this->tempDir . '/composer.json',
+            json_encode($data, \JSON_PRETTY_PRINT | \JSON_UNESCAPED_SLASHES),
+        );
+    }
+}
diff --git a/tests/Detector/ProjectDetectorTest.php b/tests/Detector/ProjectDetectorTest.php
index 2fe08fd..86736bf 100644
--- a/tests/Detector/ProjectDetectorTest.php
+++ b/tests/Detector/ProjectDetectorTest.php
@@ -13,26 +13,23 @@
 
 use Enabel\CodingStandard\Detector\ProjectDetector;
 use PHPUnit\Framework\TestCase;
+use Symfony\Component\Filesystem\Filesystem;
 
 final class ProjectDetectorTest extends TestCase
 {
     private string $tempDir;
+    private Filesystem $filesystem;
 
     protected function setUp(): void
     {
+        $this->filesystem = new Filesystem();
         $this->tempDir = sys_get_temp_dir() . '/project-detector-test-' . uniqid();
         mkdir($this->tempDir);
     }
 
     protected function tearDown(): void
     {
-        foreach (['composer.json', 'composer.lock'] as $file) {
-            $path = $this->tempDir . '/' . $file;
-            if (file_exists($path)) {
-                unlink($path);
-            }
-        }
-        rmdir($this->tempDir);
+        $this->filesystem->remove($this->tempDir);
     }
 
     public function testGetProjectNameFromComposerJson(): void
@@ -149,6 +146,165 @@ public function testGetSymfonyVersionReturnsNullWhenNotSymfony(): void
         self::assertNull($detector->getSymfonyVersion());
     }
 
+    // --- CI Provider detection ---
+
+    public function testDetectCiProvidersReturnsEmptyWhenNoCiFiles(): void
+    {
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertSame([], $detector->detectCiProviders());
+    }
+
+    public function testDetectCiProvidersDetectsGitlab(): void
+    {
+        file_put_contents($this->tempDir . '/.gitlab-ci.yml', 'stages: [test]');
+
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertSame(['gitlab'], $detector->detectCiProviders());
+    }
+
+    public function testDetectCiProvidersDetectsGithub(): void
+    {
+        $this->filesystem->mkdir($this->tempDir . '/.github/workflows');
+        file_put_contents($this->tempDir . '/.github/workflows/ci.yml', 'name: CI');
+
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertSame(['github'], $detector->detectCiProviders());
+    }
+
+    public function testDetectCiProvidersDetectsAzure(): void
+    {
+        file_put_contents($this->tempDir . '/azure-pipelines.yml', 'trigger: [main]');
+
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertSame(['azure'], $detector->detectCiProviders());
+    }
+
+    public function testDetectCiProvidersDetectsMultiple(): void
+    {
+        file_put_contents($this->tempDir . '/.gitlab-ci.yml', 'stages: [test]');
+        $this->filesystem->mkdir($this->tempDir . '/.github/workflows');
+        file_put_contents($this->tempDir . '/.github/workflows/ci.yml', 'name: CI');
+
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertSame(['gitlab', 'github'], $detector->detectCiProviders());
+    }
+
+    // --- Database detection ---
+
+    public function testDetectDatabaseReturnsNullWithoutComposeYaml(): void
+    {
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertNull($detector->detectDatabase());
+    }
+
+    public function testDetectDatabaseDetectsMariadb(): void
+    {
+        file_put_contents($this->tempDir . '/compose.yaml', "services:\n  database:\n    image: mariadb:11.4\n");
+
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertSame(['type' => 'mariadb', 'version' => '11.4'], $detector->detectDatabase());
+    }
+
+    public function testDetectDatabaseDetectsMysql(): void
+    {
+        file_put_contents($this->tempDir . '/compose.yaml', "services:\n  database:\n    image: mysql:8.4\n");
+
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertSame(['type' => 'mysql', 'version' => '8.4'], $detector->detectDatabase());
+    }
+
+    public function testDetectDatabaseDetectsPostgresql(): void
+    {
+        file_put_contents($this->tempDir . '/compose.yaml', "services:\n  database:\n    image: postgres:17\n");
+
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertSame(['type' => 'postgresql', 'version' => '17'], $detector->detectDatabase());
+    }
+
+    public function testDetectDatabaseReturnsNullWhenNoDbImage(): void
+    {
+        file_put_contents($this->tempDir . '/compose.yaml', "services:\n  app:\n    image: php:8.4\n");
+
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertNull($detector->detectDatabase());
+    }
+
+    // --- Tool detection ---
+
+    public function testHasPhpCsFixerReturnsTrueWhenFileExists(): void
+    {
+        file_put_contents($this->tempDir . '/.php-cs-fixer.dist.php', '<?php return [];');
+
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertTrue($detector->hasPhpCsFixer());
+    }
+
+    public function testHasPhpCsFixerReturnsFalseWhenFileAbsent(): void
+    {
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertFalse($detector->hasPhpCsFixer());
+    }
+
+    public function testHasPhpStanReturnsTrueWhenFileExists(): void
+    {
+        file_put_contents($this->tempDir . '/phpstan.neon', 'parameters:');
+
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertTrue($detector->hasPhpStan());
+    }
+
+    public function testHasPhpStanReturnsFalseWhenFileAbsent(): void
+    {
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertFalse($detector->hasPhpStan());
+    }
+
+    public function testHasRectorReturnsTrueWhenFileExists(): void
+    {
+        file_put_contents($this->tempDir . '/rector.php', '<?php return [];');
+
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertTrue($detector->hasRector());
+    }
+
+    public function testHasRectorReturnsFalseWhenFileAbsent(): void
+    {
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertFalse($detector->hasRector());
+    }
+
+    public function testHasPhpUnitReturnsTrueWhenFileExists(): void
+    {
+        file_put_contents($this->tempDir . '/phpunit.dist.xml', '<phpunit/>');
+
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertTrue($detector->hasPhpUnit());
+    }
+
+    public function testHasPhpUnitReturnsFalseWhenFileAbsent(): void
+    {
+        $detector = new ProjectDetector($this->tempDir);
+
+        self::assertFalse($detector->hasPhpUnit());
+    }
+
     /**
      * @param array<string, mixed> $data
      */
diff --git a/tests/Generator/GitHubActionsGeneratorTest.php b/tests/Generator/GitHubActionsGeneratorTest.php
new file mode 100644
index 0000000..50c1172
--- /dev/null
+++ b/tests/Generator/GitHubActionsGeneratorTest.php
@@ -0,0 +1,226 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the Enabel Coding Standard.
+ * Copyright (c) Enabel <https://github.com/Enabel>
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Enabel\CodingStandard\Tests\Generator;
+
+use Enabel\CodingStandard\Config\Configuration;
+use Enabel\CodingStandard\Config\ConflictResolution;
+use Enabel\CodingStandard\Generator\GitHubActionsGenerator;
+use Enabel\CodingStandard\Template\TemplateRenderer;
+use PHPUnit\Framework\TestCase;
+
+final class GitHubActionsGeneratorTest extends TestCase
+{
+    private GitHubActionsGenerator $generator;
+
+    protected function setUp(): void
+    {
+        $templatesPath = dirname(__DIR__, 2) . '/templates';
+        $renderer = new TemplateRenderer($templatesPath);
+        $this->generator = new GitHubActionsGenerator($renderer);
+    }
+
+    public function testSupportsReturnsTrueForGithub(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'github');
+
+        self::assertTrue($this->generator->supports($config));
+    }
+
+    public function testSupportsReturnsFalseForGitlab(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab');
+
+        self::assertFalse($this->generator->supports($config));
+    }
+
+    public function testSupportsReturnsFalseForNone(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'none');
+
+        self::assertFalse($this->generator->supports($config));
+    }
+
+    public function testGenerateReturnsTwoFiles(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'github');
+
+        $files = $this->generator->generate($config);
+
+        self::assertArrayHasKey('.github/workflows/ci.yml', $files);
+        self::assertArrayHasKey('.github/ci/Dockerfile', $files);
+    }
+
+    public function testDockerfileIsIdenticalToGitlab(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'github');
+
+        $files = $this->generator->generate($config);
+
+        self::assertStringContainsString('php:8.4-cli', $files['.github/ci/Dockerfile']);
+        self::assertStringContainsString('pcov', $files['.github/ci/Dockerfile']);
+        self::assertStringContainsString('composer', $files['.github/ci/Dockerfile']);
+    }
+
+    public function testCiContainsBuildImageJob(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'github');
+
+        $files = $this->generator->generate($config);
+
+        $ci = $files['.github/workflows/ci.yml'];
+        self::assertStringContainsString('build-image:', $ci);
+        self::assertStringContainsString('docker/build-push-action@v6', $ci);
+    }
+
+    public function testCiContainsPackagesWritePermission(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'github');
+
+        $files = $this->generator->generate($config);
+
+        self::assertStringContainsString('packages: write', $files['.github/workflows/ci.yml']);
+    }
+
+    public function testCiDoesNotContainSetupPhp(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'github');
+
+        $files = $this->generator->generate($config);
+
+        self::assertStringNotContainsString('shivammathur/setup-php', $files['.github/workflows/ci.yml']);
+    }
+
+    public function testCiJobsUseContainer(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'github');
+
+        $files = $this->generator->generate($config);
+
+        $ci = $files['.github/workflows/ci.yml'];
+        self::assertStringContainsString('container:', $ci);
+        self::assertStringContainsString('image: ${{ env.CI_IMAGE }}', $ci);
+    }
+
+    public function testCiWithDatabaseUsesDatabaseHostname(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'github', databaseType: 'mariadb', databaseVersion: '11.4');
+
+        $files = $this->generator->generate($config);
+
+        $ci = $files['.github/workflows/ci.yml'];
+        self::assertStringContainsString('database', $ci);
+        self::assertStringContainsString('DATABASE_URL:', $ci);
+    }
+
+    public function testCiWithDatabaseDoesNotExposePorts(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'github', databaseType: 'mariadb', databaseVersion: '11.4');
+
+        $files = $this->generator->generate($config);
+
+        self::assertStringNotContainsString('ports:', $files['.github/workflows/ci.yml']);
+    }
+
+    public function testCiWithPostgresqlDatabase(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'github', databaseType: 'postgresql', databaseVersion: '17');
+
+        $files = $this->generator->generate($config);
+
+        $ci = $files['.github/workflows/ci.yml'];
+        self::assertStringContainsString('postgres:17', $ci);
+        self::assertStringContainsString('pg_isready', $ci);
+
+        $dockerfile = $files['.github/ci/Dockerfile'];
+        self::assertStringContainsString('pdo_pgsql', $dockerfile);
+        self::assertStringContainsString('libpq-dev', $dockerfile);
+    }
+
+    public function testCiWithSymfonyHasLintJob(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'github', isSymfony: true);
+
+        $files = $this->generator->generate($config);
+
+        $ci = $files['.github/workflows/ci.yml'];
+        self::assertStringContainsString('lint:', $ci);
+        self::assertStringContainsString('lint:yaml', $ci);
+        self::assertStringContainsString('lint:twig', $ci);
+    }
+
+    public function testCiWithoutSymfonyHasNoLintJob(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'github', isSymfony: false);
+
+        $files = $this->generator->generate($config);
+
+        self::assertStringNotContainsString('lint:', $files['.github/workflows/ci.yml']);
+    }
+
+    public function testCiContainsGhcrImage(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'github', phpVersion: '8.4');
+
+        $files = $this->generator->generate($config);
+
+        self::assertStringContainsString('ghcr.io/${{ github.repository }}/ci:php8.4', $files['.github/workflows/ci.yml']);
+    }
+
+    public function testCiJobsNeedBuildImage(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'github');
+
+        $files = $this->generator->generate($config);
+
+        $ci = $files['.github/workflows/ci.yml'];
+        self::assertStringContainsString('needs: [build-image]', $ci);
+        self::assertStringContainsString('needs: [build-image, build]', $ci);
+    }
+
+    public function testGetTargetFilesReturnsBothFiles(): void
+    {
+        $expected = ['.github/workflows/ci.yml', '.github/ci/Dockerfile'];
+
+        self::assertSame($expected, $this->generator->getTargetFiles());
+    }
+
+    private function createConfiguration(
+        string $ciProvider = 'github',
+        string $phpVersion = '8.4',
+        bool $isSymfony = true,
+        bool $includePhpCsFixer = true,
+        bool $includePhpStan = true,
+        ?string $databaseType = null,
+        ?string $databaseVersion = null,
+    ): Configuration {
+        return new Configuration(
+            projectName: 'test-project',
+            phpVersion: $phpVersion,
+            phpstanLevel: 9,
+            isSymfonyProject: $isSymfony,
+            symfonyVersion: '8.0',
+            ciProvider: $ciProvider,
+            devEnvironment: 'local',
+            includeMakefile: false,
+            includePhpCsFixer: $includePhpCsFixer,
+            includePhpStan: $includePhpStan,
+            includeRector: false,
+            includePhpUnit: true,
+            srcPath: 'src',
+            testsPath: 'tests',
+            outputDir: '.',
+            conflictResolution: ConflictResolution::ASK,
+            databaseType: $databaseType,
+            databaseVersion: $databaseVersion,
+        );
+    }
+}
diff --git a/tests/Generator/GitLabCiGeneratorTest.php b/tests/Generator/GitLabCiGeneratorTest.php
new file mode 100644
index 0000000..b1c0caa
--- /dev/null
+++ b/tests/Generator/GitLabCiGeneratorTest.php
@@ -0,0 +1,241 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the Enabel Coding Standard.
+ * Copyright (c) Enabel <https://github.com/Enabel>
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Enabel\CodingStandard\Tests\Generator;
+
+use Enabel\CodingStandard\Config\Configuration;
+use Enabel\CodingStandard\Config\ConflictResolution;
+use Enabel\CodingStandard\Generator\GitLabCiGenerator;
+use Enabel\CodingStandard\Template\TemplateRenderer;
+use PHPUnit\Framework\TestCase;
+
+final class GitLabCiGeneratorTest extends TestCase
+{
+    private GitLabCiGenerator $generator;
+
+    protected function setUp(): void
+    {
+        $templatesPath = dirname(__DIR__, 2) . '/templates';
+        $renderer = new TemplateRenderer($templatesPath);
+        $this->generator = new GitLabCiGenerator($renderer);
+    }
+
+    public function testSupportsReturnsTrueForGitlab(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab');
+
+        self::assertTrue($this->generator->supports($config));
+    }
+
+    public function testSupportsReturnsFalseForGithub(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'github');
+
+        self::assertFalse($this->generator->supports($config));
+    }
+
+    public function testSupportsReturnsFalseForNone(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'none');
+
+        self::assertFalse($this->generator->supports($config));
+    }
+
+    public function testGenerateReturnsTwoFiles(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab');
+
+        $files = $this->generator->generate($config);
+
+        self::assertArrayHasKey('.gitlab-ci.yml', $files);
+        self::assertArrayHasKey('.gitlab/ci/Dockerfile', $files);
+    }
+
+    public function testDockerfileContainsPhpVersion(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab', phpVersion: '8.4');
+
+        $files = $this->generator->generate($config);
+
+        self::assertStringContainsString('php:8.4-cli', $files['.gitlab/ci/Dockerfile']);
+    }
+
+    public function testDockerfileContainsPcov(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab');
+
+        $files = $this->generator->generate($config);
+
+        self::assertStringContainsString('pcov', $files['.gitlab/ci/Dockerfile']);
+    }
+
+    public function testDockerfileContainsComposer(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab');
+
+        $files = $this->generator->generate($config);
+
+        self::assertStringContainsString('composer', $files['.gitlab/ci/Dockerfile']);
+    }
+
+    public function testDockerfileContainsPdoMysqlForMariadb(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab', databaseType: 'mariadb', databaseVersion: '11.4');
+
+        $files = $this->generator->generate($config);
+
+        self::assertStringContainsString('pdo_mysql', $files['.gitlab/ci/Dockerfile']);
+        self::assertStringNotContainsString('pdo_pgsql', $files['.gitlab/ci/Dockerfile']);
+    }
+
+    public function testDockerfileContainsPdoPgsqlForPostgresql(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab', databaseType: 'postgresql', databaseVersion: '17');
+
+        $files = $this->generator->generate($config);
+
+        self::assertStringContainsString('pdo_pgsql', $files['.gitlab/ci/Dockerfile']);
+        self::assertStringContainsString('libpq-dev', $files['.gitlab/ci/Dockerfile']);
+        self::assertStringNotContainsString('pdo_mysql', $files['.gitlab/ci/Dockerfile']);
+    }
+
+    public function testCiContainsBuildImageJob(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab');
+
+        $files = $this->generator->generate($config);
+
+        $ci = $files['.gitlab-ci.yml'];
+        self::assertStringContainsString('build:image:', $ci);
+        self::assertStringContainsString('kaniko', $ci);
+        self::assertStringContainsString('$CI_IMAGE', $ci);
+    }
+
+    public function testCiDoesNotContainAptGet(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab');
+
+        $files = $this->generator->generate($config);
+
+        self::assertStringNotContainsString('apt-get', $files['.gitlab-ci.yml']);
+    }
+
+    public function testCiDoesNotContainDockerPhpExtInstall(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab');
+
+        $files = $this->generator->generate($config);
+
+        self::assertStringNotContainsString('docker-php-ext-install', $files['.gitlab-ci.yml']);
+    }
+
+    public function testCiWithDatabaseKeepsDbWaitInPhpunit(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab', databaseType: 'mariadb', databaseVersion: '11.4');
+
+        $files = $this->generator->generate($config);
+
+        $ci = $files['.gitlab-ci.yml'];
+        self::assertStringContainsString('Waiting for database', $ci);
+        self::assertStringContainsString('PDO', $ci);
+    }
+
+    public function testCiWithoutDatabaseHasNoDbWait(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab');
+
+        $files = $this->generator->generate($config);
+
+        self::assertStringNotContainsString('Waiting for database', $files['.gitlab-ci.yml']);
+    }
+
+    public function testCiWithSymfonyHasLintJobs(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab', isSymfony: true);
+
+        $files = $this->generator->generate($config);
+
+        $ci = $files['.gitlab-ci.yml'];
+        self::assertStringContainsString('lint:yaml:', $ci);
+        self::assertStringContainsString('lint:twig:', $ci);
+        self::assertStringContainsString('lint:container:', $ci);
+        self::assertStringContainsString('lint:composer:', $ci);
+    }
+
+    public function testCiWithoutSymfonyHasNoLintJobs(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab', isSymfony: false);
+
+        $files = $this->generator->generate($config);
+
+        $ci = $files['.gitlab-ci.yml'];
+        self::assertStringNotContainsString('lint:yaml:', $ci);
+        self::assertStringNotContainsString('lint:twig:', $ci);
+    }
+
+    public function testCiUsesPreStage(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab');
+
+        $files = $this->generator->generate($config);
+
+        self::assertStringContainsString('.pre', $files['.gitlab-ci.yml']);
+    }
+
+    public function testCiUsesImageVariable(): void
+    {
+        $config = $this->createConfiguration(ciProvider: 'gitlab', phpVersion: '8.4');
+
+        $files = $this->generator->generate($config);
+
+        $ci = $files['.gitlab-ci.yml'];
+        self::assertStringContainsString('CI_IMAGE: $CI_REGISTRY_IMAGE/ci:php8.4', $ci);
+        self::assertStringContainsString('.ci-image:', $ci);
+    }
+
+    public function testGetTargetFilesReturnsBothFiles(): void
+    {
+        $expected = ['.gitlab-ci.yml', '.gitlab/ci/Dockerfile'];
+
+        self::assertSame($expected, $this->generator->getTargetFiles());
+    }
+
+    private function createConfiguration(
+        string $ciProvider = 'gitlab',
+        string $phpVersion = '8.4',
+        bool $isSymfony = true,
+        bool $includePhpCsFixer = true,
+        bool $includePhpStan = true,
+        ?string $databaseType = null,
+        ?string $databaseVersion = null,
+    ): Configuration {
+        return new Configuration(
+            projectName: 'test-project',
+            phpVersion: $phpVersion,
+            phpstanLevel: 9,
+            isSymfonyProject: $isSymfony,
+            symfonyVersion: '8.0',
+            ciProvider: $ciProvider,
+            devEnvironment: 'local',
+            includeMakefile: false,
+            includePhpCsFixer: $includePhpCsFixer,
+            includePhpStan: $includePhpStan,
+            includeRector: false,
+            includePhpUnit: true,
+            srcPath: 'src',
+            testsPath: 'tests',
+            outputDir: '.',
+            conflictResolution: ConflictResolution::ASK,
+            databaseType: $databaseType,
+            databaseVersion: $databaseVersion,
+        );
+    }
+}