Upgrade to 3.8.1

kirby/src/Cms/App.php

@@ -1062,7 +1062,7 @@ class App
 
 		// load the main config options
 		$root    = $this->root('config');
-		$options = F::load($root . '/config.php', []);
+		$options = F::load($root . '/config.php', [], allowOutput: false);
 
 		// merge into one clean options array
 		return $this->options = array_replace_recursive(Config::$data, $options);
@@ -1080,7 +1080,7 @@ class App
 		$root = $this->root('config');
 
 		// first load `config/env.php` to access its `url` option
-		$envOptions = F::load($root . '/env.php', []);
+		$envOptions = F::load($root . '/env.php', [], allowOutput: false);
 
 		// use the option from the main `config.php`,
 		// but allow the `env.php` to override it

kirby/src/Cms/AppErrors.php

@@ -163,19 +163,19 @@ trait AppErrors
 		$whoops = $this->whoops();
 		$whoops->clearHandlers();
 		$whoops->pushHandler($handler);
-		$whoops->pushHandler($this->getExceptionHookWhoopsHandler());
+		$whoops->pushHandler($this->getAdditionalWhoopsHandler());
 		$whoops->register(); // will only do something if not already registered
 	}
 
 	/**
-	 * Initializes a callback handler for triggering the `system.exception` hook
-	 *
-	 * @return \Whoops\Handler\CallbackHandler
+	 * Whoops callback handler for additional error handling
+	 * (`system.exception` hook and output to error log)
 	 */
-	protected function getExceptionHookWhoopsHandler(): CallbackHandler
+	protected function getAdditionalWhoopsHandler(): CallbackHandler
 	{
 		return new CallbackHandler(function ($exception, $inspector, $run) {
 			$this->trigger('system.exception', compact('exception'));
+			error_log($exception);
 			return Handler::DONE;
 		});
 	}

kirby/src/Cms/AppPlugins.php

@@ -717,7 +717,7 @@ trait AppPlugins
 			$class = str_replace(['.', '-', '_'], '', $name) . 'Page';
 
 			// load the model class
-			F::loadOnce($model);
+			F::loadOnce($model, allowOutput: false);
 
 			if (class_exists($class) === true) {
 				$models[$name] = $class;
@@ -908,7 +908,7 @@ trait AppPlugins
 			$styles = $dir . '/index.css';
 
 			if (is_file($entry) === true) {
-				F::loadOnce($entry);
+				F::loadOnce($entry, allowOutput: false);
 			} elseif (is_file($script) === true || is_file($styles) === true) {
 				// if no PHP file is present but an index.js or index.css,
 				// register as anonymous plugin (without actual extensions)

kirby/src/Cms/AppUsers.php

@@ -120,12 +120,12 @@ trait AppUsers
 
 		if ($allowImpersonation === true && is_string($this->user) === true) {
 			return $this->auth()->impersonate($this->user);
-		} else {
-			try {
-				return $this->auth()->user(null, $allowImpersonation);
-			} catch (Throwable) {
-				return null;
-			}
+		}
+
+		try {
+			return $this->auth()->user(null, $allowImpersonation);
+		} catch (Throwable) {
+			return null;
 		}
 	}
 

kirby/src/Cms/Auth.php

@@ -96,10 +96,7 @@ class Auth
 	 */
 	public function createChallenge(string $email, bool $long = false, string $mode = 'login')
 	{
-		$email = $this->validateEmail($email);
-
-		// rate-limit the number of challenges for DoS/DDoS protection
-		$this->track($email, false);
+		$email = Idn::decodeEmail($email);
 
 		$session = $this->kirby->session([
 			'createMode' => 'cookie',
@@ -108,8 +105,29 @@ class Auth
 
 		$timeout = $this->kirby->option('auth.challenge.timeout', 10 * 60);
 
-		$challenge = null;
-		if ($user = $this->kirby->users()->find($email)) {
+		// catch every exception to hide them from attackers
+		// unless auth debugging is enabled
+		try {
+			$this->checkRateLimit($email);
+
+			// rate-limit the number of challenges for DoS/DDoS protection
+			$this->track($email, false);
+
+			// try to find the provided user
+			$user = $this->kirby->users()->find($email);
+			if ($user === null) {
+				$this->kirby->trigger('user.login:failed', compact('email'));
+
+				throw new NotFoundException([
+					'key'  => 'user.notFound',
+					'data' => [
+						'name' => $email
+					]
+				]);
+			}
+
+			// try to find an enabled challenge that is available for that user
+			$challenge = null;
 			foreach ($this->enabledChallenges() as $name) {
 				$class = static::$challenges[$name] ?? null;
 				if (
@@ -131,23 +149,13 @@ class Auth
 				}
 			}
 
-			// if no suitable challenge was found, `$challenge === null` at this point;
-			// only leak this in debug mode
-			if ($challenge === null && $this->kirby->option('debug') === true) {
+			// if no suitable challenge was found, `$challenge === null` at this point
+			if ($challenge === null) {
 				throw new LogicException('Could not find a suitable authentication challenge');
 			}
-		} else {
-			$this->kirby->trigger('user.login:failed', compact('email'));
-
-			// only leak the non-existing user in debug mode
-			if ($this->kirby->option('debug') === true) {
-				throw new NotFoundException([
-					'key'  => 'user.notFound',
-					'data' => [
-						'name' => $email
-					]
-				]);
-			}
+		} catch (Throwable $e) {
+			// only throw the exception in auth debug mode
+			$this->fail($e);
 		}
 
 		// always set the email and timeout, even if the challenge
@@ -158,7 +166,7 @@ class Auth
 		// sleep for a random amount of milliseconds
 		// to make automated attacks harder and to
 		// avoid leaking whether the user exists
-		usleep(random_int(1000, 300000));
+		usleep(random_int(50000, 300000));
 
 		// clear the status cache
 		$this->status = null;
@@ -485,34 +493,21 @@ class Auth
 	}
 
 	/**
-	 * Ensures that email addresses with IDN domains are in Unicode format
-	 * and that the rate limit was not exceeded
-	 *
-	 * @param string $email
-	 * @return string The normalized Unicode email address
+	 * Ensures that the rate limit was not exceeded
 	 *
 	 * @throws \Kirby\Exception\PermissionException If the rate limit was exceeded
 	 */
-	protected function validateEmail(string $email): string
+	protected function checkRateLimit(string $email): void
 	{
-		// ensure that email addresses with IDN domains are in Unicode format
-		$email = Idn::decodeEmail($email);
-
 		// check for blocked ips
 		if ($this->isBlocked($email) === true) {
 			$this->kirby->trigger('user.login:failed', compact('email'));
 
-			if ($this->kirby->option('debug') === true) {
-				$message = 'Rate limit exceeded';
-			} else {
-				// avoid leaking security-relevant information
-				$message = ['key' => 'access.login'];
-			}
-
-			throw new PermissionException($message);
+			throw new PermissionException([
+				'details'  => ['reason' => 'rate-limited'],
+				'fallback' => 'Rate limit exceeded'
+			]);
 		}
-
-		return $email;
 	}
 
 	/**
@@ -529,10 +524,12 @@ class Auth
 	 */
 	public function validatePassword(string $email, string $password)
 	{
-		$email = $this->validateEmail($email);
+		$email = Idn::decodeEmail($email);
 
-		// validate the user
 		try {
+			$this->checkRateLimit($email);
+
+			// validate the user and its password
 			if ($user = $this->kirby->users()->find($email)) {
 				if ($user->validatePassword($password) === true) {
 					return $user;
@@ -546,20 +543,25 @@ class Auth
 				]
 			]);
 		} catch (Throwable $e) {
-			// log invalid login trial
-			$this->track($email);
+			$details = is_a($e, 'Kirby\Exception\Exception') === true ? $e->getDetails() : [];
+
+			// log invalid login trial unless the rate limit is already active
+			if (($details['reason'] ?? null) !== 'rate-limited') {
+				try {
+					$this->track($email);
+				} catch (Throwable $e) {
+					// $e is overwritten with the exception
+					// from the track method if there's one
+				}
+			}
 
 			// sleep for a random amount of milliseconds
 			// to make automated attacks harder
-			usleep(random_int(1000, 2000000));
+			usleep(random_int(10000, 2000000));
 
 			// keep throwing the original error in debug mode,
 			// otherwise hide it to avoid leaking security-relevant information
-			if ($this->kirby->option('debug') === true) {
-				throw $e;
-			}
-
-			throw new PermissionException(['key' => 'access.login']);
+			$this->fail($e, new PermissionException(['key' => 'access.login']));
 		}
 	}
 
@@ -841,10 +843,7 @@ class Auth
 			}
 
 			// rate-limiting
-			if ($this->isBlocked($email) === true) {
-				$this->kirby->trigger('user.login:failed', compact('email'));
-				throw new PermissionException('Rate limit exceeded');
-			}
+			$this->checkRateLimit($email);
 
 			if (
 				isset(static::$challenges[$challenge]) === true &&
@@ -860,36 +859,67 @@ class Auth
 					$this->status = null;
 
 					return $user;
-				} else {
-					throw new PermissionException(['key' => 'access.code']);
 				}
+
+				throw new PermissionException(['key' => 'access.code']);
 			}
 
 			throw new LogicException('Invalid authentication challenge: ' . $challenge);
 		} catch (Throwable $e) {
-			if (empty($email) === false && $e->getMessage() !== 'Rate limit exceeded') {
+			$details = $e instanceof \Kirby\Exception\Exception ? $e->getDetails() : [];
+
+			if (
+				empty($email) === false &&
+				($details['reason'] ?? null) !== 'rate-limited'
+			) {
 				$this->track($email);
 			}
 
 			// sleep for a random amount of milliseconds
 			// to make automated attacks harder and to
 			// avoid leaking whether the user exists
-			usleep(random_int(1000, 2000000));
+			usleep(random_int(10000, 2000000));
+
+			// specifically copy over the marker for a destroyed challenge
+			// even in production (used by the Panel to reset to the login form)
+			$challengeDestroyed = $details['challengeDestroyed'] ?? false;
+
+			$fallback = new PermissionException([
+				'details' => compact('challengeDestroyed'),
+				'key'     => 'access.code'
+			]);
 
 			// keep throwing the original error in debug mode,
 			// otherwise hide it to avoid leaking security-relevant information
-			if ($this->kirby->option('debug') === true) {
-				throw $e;
-			} else {
-				// specifically copy over the marker for a destroyed challenge
-				// even in production (used by the Panel to reset to the login form)
-				$challengeDestroyed = $e->getDetails()['challengeDestroyed'] ?? false;
+			$this->fail($e, $fallback);
+		}
+	}
 
-				throw new PermissionException([
-					'details' => compact('challengeDestroyed'),
-					'key'     => 'access.code'
-				]);
-			}
+	/**
+	 * Throws an exception only in debug mode, otherwise falls back
+	 * to a public error without sensitive information
+	 *
+	 * @throws \Throwable Either the passed `$exception` or the `$fallback`
+	 *                    (no exception if debugging is disabled and no fallback was passed)
+	 */
+	protected function fail(Throwable $exception, Throwable $fallback = null): void
+	{
+		$debug = $this->kirby->option('auth.debug', 'log');
+
+		// throw the original exception only in debug mode
+		if ($debug === true) {
+			throw $exception;
+		}
+
+		// otherwise hide the real error and only print it to the error log
+		// unless disabled by setting `auth.debug` to `false`
+		if ($debug === 'log') {
+			error_log($exception); // @codeCoverageIgnore
+		}
+
+		// only throw an error in production if requested by the calling method
+		if ($fallback !== null) {
+			throw $fallback;
 		}
 	}
 

kirby/src/Cms/Auth/Status.php

@@ -95,9 +95,9 @@ class Status
 
 		if ($automaticFallback === false) {
 			return $this->challenge;
-		} else {
-			return $this->challenge ?? $this->challengeFallback;
 		}
+
+		return $this->challenge ?? $this->challengeFallback;
 	}
 
 	/**

kirby/src/Cms/Blueprint.php

@@ -731,7 +731,7 @@ class Blueprint
 		$preset = static::$presets[$props['preset']];
 
 		if (is_string($preset) === true) {
-			$preset = require $preset;
+			$preset = F::load($preset, allowOutput: false);
 		}
 
 		return $preset($props);

kirby/src/Cms/Collection.php

@@ -114,11 +114,14 @@ class Collection extends BaseCollection
 	{
 		if (count($args) === 1) {
 			// try to determine the key from the provided item
-			if (is_object($args[0]) === true && is_callable([$args[0], 'id']) === true) {
+			if (
+				is_object($args[0]) === true &&
+				is_callable([$args[0], 'id']) === true
+			) {
 				return parent::append($args[0]->id(), $args[0]);
-			} else {
-				return parent::append($args[0]);
 			}
+
+			return parent::append($args[0]);
 		}
 
 		return parent::append(...$args);

kirby/src/Cms/Collections.php

@@ -123,7 +123,7 @@ class Collections
 		$file = $kirby->root('collections') . '/' . $name . '.php';
 
 		if (is_file($file) === true) {
-			$collection = F::load($file);
+			$collection = F::load($file, allowOutput: false);
 
 			if ($collection instanceof Closure) {
 				return $collection;

kirby/src/Cms/Content.php

@@ -115,7 +115,7 @@ class Content
 			$oldField = $oldFields->get($name);
 
 			// field name and type matches with old template
-			if ($oldField && $oldField->type() === $newField->type()) {
+			if ($oldField?->type() === $newField->type()) {
 				$data[$name] = $content->get($name)->value();
 			} else {
 				$data[$name] = $newField->default();

kirby/src/Cms/File.php

@@ -451,9 +451,9 @@ class File extends ModelWithContent
 	 * Return the permanent URL to the file using its UUID
 	 * @since 3.8.0
 	 */
-	public function permalink(): string
+	public function permalink(): string|null
 	{
-		return $this->uuid()->url();
+		return $this->uuid()?->url();
 	}
 
 	/**

kirby/src/Cms/FileActions.php

@@ -8,6 +8,7 @@ use Kirby\Exception\LogicException;
 use Kirby\Filesystem\F;
 use Kirby\Form\Form;
 use Kirby\Uuid\Uuid;
+use Kirby\Uuid\Uuids;
 
 /**
  * FileActions
@@ -155,7 +156,9 @@ trait FileActions
 		$copy = $page->clone()->file($this->filename());
 
 		// overwrite with new UUID (remove old, add new)
-		$copy = $copy->save(['uuid' => Uuid::generate()]);
+		if (Uuids::enabled() === true) {
+			$copy = $copy->save(['uuid' => Uuid::generate()]);
+		}
 
 		return $copy;
 	}
@@ -191,7 +194,9 @@ trait FileActions
 
 		// make sure that a UUID gets generated and
 		// added to content right away
-		$content['uuid'] = Uuid::generate();
+		if (Uuids::enabled() === true) {
+			$content['uuid'] ??= Uuid::generate();
+		}
 
 		// create a form for the file
 		$form = Form::for($file, ['values' => $content]);
@@ -336,7 +341,7 @@ trait FileActions
 			$this->lock()?->remove();
 
 			// clear UUID cache
-			$this->uuid()->clear();
+			$this->uuid()?->clear();
 		}
 
 		return $this;

kirby/src/Cms/Languages.php

@@ -81,7 +81,7 @@ class Languages extends Collection
 		$files     = glob(App::instance()->root('languages') . '/*.php');
 
 		foreach ($files as $file) {
-			$props = F::load($file);
+			$props = F::load($file, allowOutput: false);
 
 			if (is_array($props) === true) {
 				// inject the language code from the filename

kirby/src/Cms/Loader.php

@@ -160,12 +160,12 @@ class Loader
 	{
 		if (is_string($item) === true) {
 			$item = match (F::extension($item)) {
-				'php'   => require $item,
+				'php'   => F::load($item, allowOutput: false),
 				default => Data::read($item)
 			};
 		}
 
-		if (is_callable($item)) {
+		if (is_callable($item) === true) {
 			$item = $item($this->kirby);
 		}
 

kirby/src/Cms/ModelWithContent.php

@@ -632,7 +632,7 @@ abstract class ModelWithContent extends Model implements Identifiable
 	 * Returns the model's UUID
 	 * @since 3.8.0
 	 */
-	public function uuid(): Uuid
+	public function uuid(): Uuid|null
 	{
 		return Uuid::for($this);
 	}

kirby/src/Cms/Page.php

@@ -964,9 +964,9 @@ class Page extends ModelWithContent
 	 * Return the permanent URL to the page using its UUID
 	 * @since 3.8.0
 	 */
-	public function permalink(): string
+	public function permalink(): string|null
 	{
-		return $this->uuid()->url();
+		return $this->uuid()?->url();
 	}
 
 	/**

kirby/src/Cms/PageActions.php

@@ -14,6 +14,7 @@ use Kirby\Toolkit\A;
 use Kirby\Toolkit\I18n;
 use Kirby\Toolkit\Str;
 use Kirby\Uuid\Uuid;
+use Kirby\Uuid\Uuids;
 
 /**
  * PageActions
@@ -108,7 +109,7 @@ trait PageActions
 			]);
 
 			// clear UUID cache recursively (for children and files as well)
-			$oldPage->uuid()->clear(true);
+			$oldPage->uuid()?->clear(true);
 
 			if ($oldPage->exists() === true) {
 				// remove the lock of the old page
@@ -443,7 +444,9 @@ trait PageActions
 		}
 
 		// overwrite with new UUID (remove old, add new)
-		$copy = $copy->save(['uuid' => Uuid::generate()]);
+		if (Uuids::enabled() === true) {
+			$copy = $copy->save(['uuid' => Uuid::generate()]);
+		}
 
 		// add copy to siblings
 		static::updateParentCollections($copy, 'append', $parentModel);
@@ -467,7 +470,10 @@ trait PageActions
 		// make sure that a UUID gets generated and
 		// added to content right away
 		$props['content'] ??= [];
-		$props['content']['uuid'] ??= Uuid::generate();
+
+		if (Uuids::enabled() === true) {
+			$props['content']['uuid'] ??= Uuid::generate();
+		}
 
 		// create a temporary page object
 		$page = Page::factory($props);
@@ -596,7 +602,7 @@ trait PageActions
 	{
 		return $this->commit('delete', ['page' => $this, 'force' => $force], function ($page, $force) {
 			// clear UUID cache
-			$page->uuid()->clear();
+			$page->uuid()?->clear();
 
 			// delete all files individually
 			foreach ($page->files() as $file) {

kirby/src/Cms/PageSiblings.php

@@ -122,9 +122,9 @@ trait PageSiblings
 	{
 		if ($this->isDraft() === true) {
 			return $this->parentModel()->drafts();
-		} else {
-			return $this->parentModel()->children();
 		}
+
+		return $this->parentModel()->children();
 	}
 
 	/**

kirby/src/Cms/Plugin.php

@@ -2,12 +2,15 @@
 
 namespace Kirby\Cms;
 
+use Composer\InstalledVersions;
 use Exception;
 use Kirby\Cms\System\UpdateStatus;
 use Kirby\Data\Data;
 use Kirby\Exception\InvalidArgumentException;
 use Kirby\Toolkit\A;
+use Kirby\Toolkit\Str;
 use Kirby\Toolkit\V;
+use Throwable;
 
 /**
  * Represents a Plugin and handles parsing of
@@ -269,9 +272,22 @@ class Plugin extends Model
 	 */
 	public function version(): string|null
 	{
-		$version = $this->info()['version'] ?? null;
+		$composerName = $this->info()['name'] ?? null;
+		$version      = $this->info()['version'] ?? null;
 
-		if (is_string($version) !== true || $version === '') {
+		try {
+			// if plugin doesn't have version key in composer.json file
+			// try to get version from "vendor/composer/installed.php"
+			$version ??= InstalledVersions::getPrettyVersion($composerName);
+		} catch (Throwable) {
+			return null;
+		}
+
+		if (
+			is_string($version) !== true ||
+			$version === '' ||
+			Str::endsWith($version, '+no-version-set')
+		) {
 			return null;
 		}
 

kirby/src/Cms/System.php

@@ -322,12 +322,11 @@ class System
 
 		// only return the actual license key if the
 		// current user has appropriate permissions
-		$user = $this->app->user();
-		if ($user && $user->isAdmin() === true) {
+		if ($this->app->user()?->isAdmin() === true) {
 			return $license['license'];
-		} else {
-			return true;
 		}
+
+		return true;
 	}
 
 	/**

kirby/src/Cms/User.php

@@ -157,9 +157,9 @@ class User extends ModelWithContent
 	{
 		if ($relative === true) {
 			return 'users/' . $this->id();
-		} else {
-			return $this->kirby()->url('api') . '/users/' . $this->id();
 		}
+
+		return $this->kirby()->url('api') . '/users/' . $this->id();
 	}
 
 	/**

kirby/src/Cms/UserActions.php

@@ -308,12 +308,12 @@ trait UserActions
 		$path = $this->root() . '/index.php';
 
 		if (is_file($path) === true) {
-			$credentials = F::load($path);
+			$credentials = F::load($path, allowOutput: false);
 
 			return is_array($credentials) === false ? [] : $credentials;
-		} else {
-			return [];
 		}
+
+		return [];
 	}
 
 	/**

kirby/src/Cms/Users.php

@@ -148,7 +148,7 @@ class Users extends Collection
 			// get role information
 			$path = $root . '/' . $userDirectory . '/index.php';
 			if (is_file($path) === true) {
-				$credentials = F::load($path);
+				$credentials = F::load($path, allowOutput: false);
 			}
 
 			// create user model based on role

kirby/src/Data/PHP.php

@@ -61,7 +61,7 @@ class PHP extends Handler
 			throw new Exception('The file "' . $file . '" does not exist');
 		}
 
-		return (array)F::load($file, []);
+		return (array)F::load($file, [], allowOutput: false);
 	}
 
 	/**

kirby/src/Database/Query.php

@@ -898,9 +898,8 @@ class Query
 		if (preg_match('!^findBy([a-z]+)!i', $method, $match)) {
 			$column = Str::lower($match[1]);
 			return $this->findBy($column, $arguments[0]);
-		} else {
-			throw new InvalidArgumentException('Invalid query method: ' . $method, static::ERROR_INVALID_QUERY_METHOD);
 		}
+		throw new InvalidArgumentException('Invalid query method: ' . $method, static::ERROR_INVALID_QUERY_METHOD);
 	}
 
 	/**
@@ -1027,8 +1026,8 @@ class Query
 		// attach the where clause
 		if (empty($current) === false) {
 			return $current . ' ' . $mode . ' ' . $result;
-		} else {
-			return $result;
 		}
+
+		return $result;
 	}
 }

kirby/src/Database/Sql.php

@@ -684,9 +684,9 @@ abstract class Sql
 			}
 
 			return implode(', ', $result);
-		} else {
-			return $columns;
 		}
+
+		return $columns;
 	}
 
 	/**
@@ -833,9 +833,9 @@ abstract class Sql
 
 		if ($set === true) {
 			return $this->valueSet($table, $values, $separator, $enforceQualified);
-		} else {
-			return $this->valueList($table, $values, $separator, $enforceQualified);
 		}
+
+		return $this->valueList($table, $values, $separator, $enforceQualified);
 	}
 
 	/**

kirby/src/Filesystem/F.php

@@ -5,6 +5,7 @@ namespace Kirby\Filesystem;
 use Exception;
 use IntlDateFormatter;
 use Kirby\Cms\Helpers;
+use Kirby\Http\Response;
 use Kirby\Toolkit\I18n;
 use Kirby\Toolkit\Str;
 use Throwable;
@@ -347,8 +348,12 @@ class F
 	 *
 	 * @param array $data Optional array of variables to extract in the variable scope
 	 */
-	public static function load(string $file, $fallback = null, array $data = [])
-	{
+	public static function load(
+		string $file,
+		mixed $fallback = null,
+		array $data = [],
+		bool $allowOutput = true
+	) {
 		if (is_file($file) === false) {
 			return $fallback;
 		}
@@ -356,9 +361,21 @@ class F
 		// we use the loadIsolated() method here to prevent the included
 		// file from overwriting our $fallback in this variable scope; see
 		// https://www.php.net/manual/en/function.include.php#example-124
-		$result = static::loadIsolated($file, $data);
+		$callback = fn () => static::loadIsolated($file, $data);
 
-		if ($fallback !== null && gettype($result) !== gettype($fallback)) {
+		// if the loaded file should not produce any output,
+		// call the loaidIsolated method from the Response class
+		// which checks for unintended ouput and throws an error if detected
+		if ($allowOutput === false) {
+			$result = Response::guardAgainstOutput($callback);
+		} else {
+			$result = $callback();
+		}
+
+		if (
+			$fallback !== null &&
+			gettype($result) !== gettype($fallback)
+		) {
 			return $fallback;
 		}
 
@@ -369,24 +386,28 @@ class F
 	 * A super simple class autoloader
 	 * @since 3.7.0
 	 */
-	public static function loadClasses(array $classmap, string|null $base = null): void
-	{
+	public static function loadClasses(
+		array $classmap,
+		string|null $base = null
+	): void {
 		// convert all classnames to lowercase
 		$classmap = array_change_key_case($classmap);
 
-		spl_autoload_register(function ($class) use ($classmap, $base) {
-			$class = strtolower($class);
+		spl_autoload_register(
+			fn ($class) => Response::guardAgainstOutput(function () use ($class, $classmap, $base) {
+				$class = strtolower($class);
 
-			if (!isset($classmap[$class])) {
-				return false;
-			}
+				if (isset($classmap[$class]) === false) {
+					return false;
+				}
 
-			if ($base) {
-				include $base . '/' . $classmap[$class];
-			} else {
-				include $classmap[$class];
-			}
-		});
+				if ($base) {
+					include $base . '/' . $classmap[$class];
+				} else {
+					include $classmap[$class];
+				}
+			})
+		);
 	}
 
 	/**
@@ -408,13 +429,22 @@ class F
 	 * Loads a file using `include_once()` and
 	 * returns whether loading was successful
 	 */
-	public static function loadOnce(string $file): bool
-	{
+	public static function loadOnce(
+		string $file,
+		bool $allowOutput = true
+	): bool {
 		if (is_file($file) === false) {
 			return false;
 		}
 
-		include_once $file;
+		$callback = fn () => include_once $file;
+
+		if ($allowOutput === false) {
+			Response::guardAgainstOutput($callback);
+		} else {
+			$callback();
+		}
+
 		return true;
 	}
 

kirby/src/Http/Cookie.php

@@ -73,12 +73,14 @@ class Cookie
 		if ($minutes > 1000000000) {
 			// absolute timestamp
 			return $minutes;
-		} elseif ($minutes > 0) {
+		}
+
+		if ($minutes > 0) {
 			// minutes from now
 			return time() + ($minutes * 60);
-		} else {
-			return 0;
 		}
+
+		return 0;
 	}
 
 	/**

kirby/src/Http/Environment.php

@@ -786,12 +786,20 @@ class Environment
 
 		// load the config for the host
 		if (empty($host) === false) {
-			$configHost = F::load($root . '/config.' . $host . '.php', []);
+			$configHost = F::load(
+				file: $root . '/config.' . $host . '.php',
+				fallback: [],
+				allowOutput: false
+			);
 		}
 
 		// load the config for the server IP
 		if (empty($addr) === false) {
-			$configAddr = F::load($root . '/config.' . $addr . '.php', []);
+			$configAddr = F::load(
+				file: $root . '/config.' . $addr . '.php',
+				fallback: [],
+				allowOutput: false
+			);
 		}
 
 		return array_replace_recursive($configHost, $configAddr);

kirby/src/Http/Remote.php

@@ -323,9 +323,9 @@ class Remote
 	{
 		if (is_object($data) || is_array($data)) {
 			return http_build_query($data);
-		} else {
-			return $data;
 		}
+
+		return $data;
 	}
 
 	/**

kirby/src/Http/Response.php

@@ -2,7 +2,9 @@
 
 namespace Kirby\Http;
 
+use Closure;
 use Exception;
+use Kirby\Exception\LogicException;
 use Kirby\Filesystem\F;
 use Throwable;
 
@@ -182,6 +184,23 @@ class Response
 		die(static::redirect($url, $code));
 	}
 
+	/**
+	 * Ensures that the callback does not produce the first body output
+	 * (used to show when loading a file creates side effects)
+	 */
+	public static function guardAgainstOutput(Closure $callback, ...$args): mixed
+	{
+		$before = headers_sent();
+		$result = $callback(...$args);
+		$after  = headers_sent($file, $line);
+
+		if ($before === false && $after === true) {
+			throw new LogicException("Disallowed output from file $file:$line, possible accidental whitespace?");
+		}
+
+		return $result;
+	}
+
 	/**
 	 * Getter for single headers
 	 *

kirby/src/Panel/File.php

@@ -76,7 +76,9 @@ class File extends Model
 		// for markdown notation or the UUID for Kirbytext (since
 		// Kirbytags support can resolve UUIDs directly)
 		if ($absolute === true) {
-			$url = $type === 'markdown' ? $this->model->permalink() : $this->model->uuid();
+			$url   = $type === 'markdown' ? $this->model->permalink() : $this->model->uuid();
+			// if UUIDs are disabled, fall back to URL
+			$url ??= $this->model->url();
 		}
 
 

kirby/src/Panel/Model.php

@@ -286,7 +286,7 @@ abstract class Model
 			'link'     => $this->url(true),
 			'sortable' => true,
 			'text'     => $this->model->toSafeString($params['text'] ?? false),
-			'uuid'     => $this->model->uuid()->toString(),
+			'uuid'     => $this->model->uuid()?->toString() ?? $this->model->id(),
 		];
 	}
 

kirby/src/Panel/Page.php

@@ -49,10 +49,15 @@ class Page extends Model
 
 		$title = $this->model->title();
 
-		return match ($type) {
-			'markdown' => '[' . $title . '](' . $this->model->permalink() . ')',
-			default    => '(link: ' . $this->model->uuid() . ' text: ' . $title . ')'
-		};
+		// type: markdown
+		if ($type === 'markdown') {
+			$url = $this->model->permalink() ?? $this->model->url();
+			return '[' . $title . '](' . $url . ')';
+		}
+
+		// type: kirbytext
+		$link = $this->model->uuid() ?? $this->model->uri();
+		return '(link: ' . $link . ' text: ' . $title . ')';
 	}
 
 	/**

kirby/src/Session/Session.php

@@ -611,12 +611,15 @@ class Session
 		// now make sure that we have a valid timestamp
 		if (is_int($time)) {
 			return $time;
-		} else {
-			throw new InvalidArgumentException([
-				'data'      => ['method' => 'Session::timeToTimestamp', 'argument' => '$time'],
-				'translate' => false
-			]);
 		}
+
+		throw new InvalidArgumentException([
+			'data' => [
+				'method'   => 'Session::timeToTimestamp',
+				'argument' => '$time'
+			],
+			'translate' => false
+		]);
 	}
 
 	/**

kirby/src/Session/SessionData.php

@@ -177,14 +177,19 @@ class SessionData
 	{
 		if (is_string($key)) {
 			return $this->data[$key] ?? $default;
-		} elseif ($key === null) {
-			return $this->data;
-		} else {
-			throw new InvalidArgumentException([
-				'data'      => ['method' => 'SessionData::get', 'argument' => 'key'],
-				'translate' => false
-			]);
 		}
+
+		if ($key === null) {
+			return $this->data;
+		}
+
+		throw new InvalidArgumentException([
+			'data' => [
+				'method'   => 'SessionData::get',
+				'argument' => 'key'
+			],
+			'translate' => false
+		]);
 	}
 
 	/**

kirby/src/Toolkit/A.php

@@ -156,47 +156,65 @@ class A
 	/**
 	 * Merges arrays recursively
 	 *
-	 * @param int $mode Behavior for elements with numeric keys;
-	 *                  A::MERGE_APPEND:    elements are appended, keys are reset;
-	 *                  A::MERGE_OVERWRITE: elements are overwritten, keys are preserved
-	 *                  A::MERGE_REPLACE:   non-associative arrays are completely replaced
+	 * If last argument is an integer, it defines the
+	 * behavior for elements with numeric keys;
+	 * - A::MERGE_OVERWRITE:  elements are overwritten, keys are preserved
+	 * - A::MERGE_APPEND:     elements are appended, keys are reset;
+	 * - A::MERGE_REPLACE:    non-associative arrays are completely replaced
 	 */
-	public static function merge(array $array1, array $array2, int $mode = A::MERGE_APPEND): array
+	public static function merge(array|int ...$arrays): array
 	{
-		$merged = $array1;
+		// get mode from parameters
+		$last = A::last($arrays);
+		$mode = is_int($last) ? array_pop($arrays) : A::MERGE_APPEND;
+
+		// get the first two arrays that should be merged
+		$merged = array_shift($arrays);
+		$join   = array_shift($arrays);
 
 		if (
-			static::isAssociative($array1) === false &&
+			static::isAssociative($merged) === false &&
 			$mode === static::MERGE_REPLACE
 		) {
-			return $array2;
-		}
+			$merged = $join;
+		} else {
+			foreach ($join as $key => $value) {
+				// append to the merged array, don't overwrite numeric keys
+				if (
+					is_int($key) === true &&
+					$mode === static::MERGE_APPEND
+				) {
+					$merged[] = $value;
 
-		foreach ($array2 as $key => $value) {
-			// append to the merged array, don't overwrite numeric keys
-			if (is_int($key) === true && $mode === static::MERGE_APPEND) {
-				$merged[] = $value;
+				// recursively merge the two array values
+				} elseif (
+					is_array($value) === true &&
+					isset($merged[$key]) === true &&
+					is_array($merged[$key]) === true
+				) {
+					$merged[$key] = static::merge($merged[$key], $value, $mode);
 
-			// recursively merge the two array values
-			} elseif (
-				is_array($value) === true &&
-				isset($merged[$key]) === true &&
-				is_array($merged[$key]) === true
-			) {
-				$merged[$key] = static::merge($merged[$key], $value, $mode);
+				// simply overwrite with the value from the second array
+				} else {
+					$merged[$key] = $value;
+				}
+			}
 
-			// simply overwrite with the value from the second array
-			} else {
-				$merged[$key] = $value;
+			if ($mode === static::MERGE_APPEND) {
+				// the keys don't make sense anymore, reset them
+				// array_merge() is the simplest way to renumber
+				// arrays that have both numeric and string keys;
+				// besides the keys, nothing changes here
+				$merged = array_merge($merged, []);
 			}
 		}
 
-		if ($mode === static::MERGE_APPEND) {
-			// the keys don't make sense anymore, reset them
-			// array_merge() is the simplest way to renumber
-			// arrays that have both numeric and string keys;
-			// besides the keys, nothing changes here
-			$merged = array_merge($merged, []);
+		// if more than two arrays need to be merged, add the result
+		// as first array and the mode to the end and call the method again
+		if (count($arrays) > 0) {
+			array_unshift($arrays, $merged);
+			array_push($arrays, $mode);
+			return static::merge(...$arrays);
 		}
 
 		return $merged;

kirby/src/Toolkit/Component.php

@@ -232,7 +232,7 @@ class Component
 				throw new Exception('Component definition ' . $definition . ' does not exist');
 			}
 
-			static::$types[$type] = $definition = F::load($definition);
+			static::$types[$type] = $definition = F::load($definition, allowOutput: false);
 		}
 
 		return $definition;
@@ -254,7 +254,11 @@ class Component
 
 		if (isset($definition['extends']) === true) {
 			// extend other definitions
-			$options = array_replace_recursive(static::defaults(), static::load($definition['extends']), $definition);
+			$options = array_replace_recursive(
+				static::defaults(),
+				static::load($definition['extends']),
+				$definition
+			);
 		} else {
 			// inject defaults
 			$options = array_replace_recursive(static::defaults(), $definition);
@@ -266,10 +270,14 @@ class Component
 				if (isset(static::$mixins[$mixin]) === true) {
 					if (is_string(static::$mixins[$mixin]) === true) {
 						// resolve a path to a mixin on demand
-						static::$mixins[$mixin] = include static::$mixins[$mixin];
+
+						static::$mixins[$mixin] = F::load(static::$mixins[$mixin], allowOutput: false);
 					}
 
-					$options = array_replace_recursive(static::$mixins[$mixin], $options);
+					$options = array_replace_recursive(
+						static::$mixins[$mixin],
+						$options
+					);
 				}
 			}
 		}

kirby/src/Toolkit/Html.php

@@ -281,10 +281,10 @@ class Html extends Xml
 	 */
 	public static function gist(string $url, string|null $file = null, array $attr = []): string
 	{
-		if ($file === null) {
-			$src = $url . '.js';
-		} else {
-			$src = $url . '.js?file=' . $file;
+		$src = $url . '.js';
+
+		if ($file !== null) {
+			$src .= '?file=' . $file;
 		}
 
 		return static::tag('script', '', array_merge($attr, ['src' => $src]));

kirby/src/Toolkit/Locale.php

@@ -117,11 +117,13 @@ class Locale
 			}
 
 			return $convertedLocale;
-		} elseif (is_string($locale)) {
-			return [LC_ALL => $locale];
-		} else {
-			throw new InvalidArgumentException('Locale must be string or array');
 		}
+
+		if (is_string($locale) === true) {
+			return [LC_ALL => $locale];
+		}
+
+		throw new InvalidArgumentException('Locale must be string or array');
 	}
 
 	/**

kirby/src/Toolkit/Query.php

@@ -165,12 +165,12 @@ class Query
 			$args = array_map('self::parameter', $args);
 
 			return compact('method', 'args');
-		} else {
-			return [
-				'method' => $part,
-				'args'   => []
-			];
 		}
+
+		return [
+			'method' => $part,
+			'args'   => []
+		];
 	}
 
 	/**

kirby/src/Toolkit/Silo.php

@@ -31,10 +31,10 @@ class Silo
 	{
 		if (is_array($key) === true) {
 			return static::$data = array_merge(static::$data, $key);
-		} else {
-			static::$data[$key] = $value;
-			return static::$data;
 		}
+
+		static::$data[$key] = $value;
+		return static::$data;
 	}
 
 	/**

kirby/src/Toolkit/Xml.php

@@ -182,9 +182,9 @@ class Xml
 
 		if ($head === true) {
 			return '<?xml version="1.0" encoding="UTF-8"?>' . PHP_EOL . $result;
-		} else {
-			return $result;
 		}
+
+		return $result;
 	}
 
 	/**
@@ -345,13 +345,12 @@ class Xml
 			// we didn't find any XML children above, only use the string value
 			$element = (string)$element;
 
-			if (count($array) > 0) {
-				$array['@value'] = $element;
-
-				return $array;
-			} else {
+			if (count($array) === 0) {
 				return $element;
 			}
+
+			$array['@value'] = $element;
+			return $array;
 		}
 	}
 

kirby/src/Uuid/Identifiable.php

@@ -17,5 +17,5 @@ namespace Kirby\Uuid;
 interface Identifiable
 {
 	public function id();
-	public function uuid(): Uuid;
+	public function uuid(): Uuid|null;
 }

kirby/src/Uuid/Uuid.php

@@ -63,6 +63,12 @@ class Uuid
 		Identifiable|null $model = null,
 		Collection|null $context = null
 	) {
+		// throw exception when globally disabled
+		if (Uuids::enabled() === false) {
+			throw new LogicException('UUIDs have been disabled via the `content.uuid` config option.');
+		}
+
+
 		$this->context = $context;
 		$this->model   = $model;
 
@@ -143,7 +149,13 @@ class Uuid
 	final public static function for(
 		string|Identifiable $seed,
 		Collection|null $context = null
-	): static {
+	): static|null {
+		// if globally disabled, return null
+		if (Uuids::enabled() === false) {
+			return null;
+		}
+
+		// for UUID string
 		if (is_string($seed) === true) {
 			return match (Str::before($seed, '://')) {
 				'page'   => new PageUuid(uuid: $seed, context: $context),
@@ -157,6 +169,7 @@ class Uuid
 			};
 		}
 
+		// for model object
 		return match (true) {
 			$seed instanceof Page
 				=> new PageUuid(model: $seed, context: $context),
@@ -229,6 +242,11 @@ class Uuid
 		string $string,
 		string|null $type = null
 	): bool {
+		// always return false when UUIDs have been disabled
+		if (Uuids::enabled() === false) {
+			return false;
+		}
+
 		$type  ??= implode('|', Uri::$schemes);
 		$pattern = sprintf('!^(%s)://(.*)!', $type);
 

kirby/src/Uuid/Uuids.php

@@ -5,6 +5,7 @@ namespace Kirby\Uuid;
 use Closure;
 use Kirby\Cache\Cache;
 use Kirby\Cms\App;
+use Kirby\Exception\LogicException;
 
 /**
  * Helper methods that deal with the entirety of UUIDs in the system
@@ -79,6 +80,11 @@ class Uuids
 		// }
 	}
 
+	public static function enabled(): bool
+	{
+		return App::instance()->option('content.uuid') !== false;
+	}
+
 	/**
 	 * Generates UUID for all identifiable models of type
 	 *
@@ -86,6 +92,10 @@ class Uuids
 	 */
 	public static function generate(string $type = 'all'): void
 	{
+		if (static::enabled() === false) {
+			throw new LogicException('UUIDs have been disabled via the `content.uuid` config option.');
+		}
+
 		static::each(
 			fn (Identifiable $model) => Uuid::for($model)->id(),
 			$type
@@ -100,6 +110,10 @@ class Uuids
 	 */
 	public static function populate(string $type = 'all'): void
 	{
+		if (static::enabled() === false) {
+			throw new LogicException('UUIDs have been disabled via the `content.uuid` config option.');
+		}
+
 		static::each(
 			fn (Identifiable $model) => Uuid::for($model)->populate(),
 			$type