Serve any type of file

In the page declaration, only specify the class name, and headers if needed:

<?php

$config = [
    'acme' => [
        Core_Page::TYPE => [
            /* ... */
            '/api/customers/' => [
                'class' => Acme_Page_Api_Customer::class,
                '_headers' => [
                    'Content-Type' => 'application/json',
                ],
            ],
            /* ... */
        ],
    ],
];

In the class, cancel any potential template, then render the desired content:

<?php

declare(strict_types=1);

class Acme_Page_Api_Customer extends Core_Page
{
    public function execute(): void
    {
        $this->setTemplate(null);
    }
    
    public function render(): string
    {
        return json_encode(
            [
                'customers' => [
                    [
                        'identifier' => 1,
                        'name' => 'John Doe',
                    ],
                ],
            ]
        );
    }
}

Examples

Warning: A file that exists within the package overrides a page defined in the configuration.

sitemap.xml

<?php

$config = [
    'acme' => [
        Core_Page::TYPE => [
            /* ... */
            '/sitemap.xml' => [
                'class' => Acme_Page_Sitemap::class,
                '_headers' => [
                    'Content-Type' => 'application/xml',
                ],
            ],
            /* ... */
        ],
    ],
];

<?php

declare(strict_types=1);

class Acme_Page_Sitemap extends Core_Page
{
    public function execute(): void
    {
        $this->setTemplate(null);
    }
    
    public function render(): string
    {
        $pages = App::db()->getAll('pages');
        
        $xml = '<?xml version="1.0" encoding="UTF-8"?>' . "\n";
        $xml .= '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">' . "\n";
        foreach ($pages as $page) {
            $xml .= '<url><loc>' . $this->getBaseUrl($page['slug']) . '</loc></url>' . "\n";
        }
        $xml .= '</urlset>';

        return $xml;
    }
}

robots.txt

<?php

$config = [
    'acme' => [
        Core_Page::TYPE => [
            /* ... */
            '/sitemap.xml' => [
                'class' => Acme_Page_Robots::class,
                '_headers' => [
                    'Content-Type' => 'text/plain',
                ],
            ],
            /* ... */
        ],
    ],
];

<?php

declare(strict_types=1);

class Acme_Page_Robots extends Core_Page
{
    public function execute(): void
    {
        $this->setTemplate(null);
    }
    
    public function render(): string
    {
        $robots = 'User-agent: *' . "\n";
        
        if (App::getEnvironment() === 'default' {
            $robots .= 'Allow: /' . "\n";
        } else {
            $robots .= 'Disallow: /' . "\n";
        }
        
        return $robots;
    }
}