diff --git a/includes/Constants.php b/includes/Constants.php
index 10bb7ccc..4800b466 100644
--- a/includes/Constants.php
+++ b/includes/Constants.php
@@ -60,6 +60,17 @@ final class Constants {
 	 */
 	public const PREF_KEY_SKIN_VERSION = 'VectorSkinVersion';
 
+	// These are used in the Feature Management System.
+	/**
+	 * @var string
+	 */
+	public const CONFIG_KEY_FULLY_INITIALISED = 'FullyInitialised';
+
+	/**
+	 * @var string
+	 */
+	public const REQUIREMENT_FULLY_INITIALISED = 'FullyInitialised';
+
 	/**
 	 * This class is for namespacing constants only. Forbid construction.
 	 * @throws FatalError
diff --git a/includes/FeatureManagement/Requirements/DynamicConfigRequirement.php b/includes/FeatureManagement/Requirements/DynamicConfigRequirement.php
new file mode 100644
index 00000000..827aa76d
--- /dev/null
+++ b/includes/FeatureManagement/Requirements/DynamicConfigRequirement.php
@@ -0,0 +1,97 @@
+<?php
+
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @since 1.35
+ */
+
+namespace Vector\FeatureManagement\Requirements;
+
+use Vector\FeatureManagement\Requirement;
+
+/**
+ * Some application state changes throughout the lifetime of the application, e.g.
+ * `wgFullyInitialised`, which signals whether the application boot process has finished and
+ * critical resources like database connections are available.
+ *
+ * The `DynamicStateRequirement` allows us to define requirements that lazily evaluate the
+ * application state statically, e.g.
+ *
+ * ```lang=php
+ * $featureManager->registerComplexRequirement(
+ *   new DynamicConfigRequirement(
+ *     $config,
+ *     'FullyInitialised',
+ *     'Foo'
+ *   )
+ * );
+ * ```
+ *
+ * registers a requirement that will evaluate to true only when `mediawiki/includes/Setup.php` has
+ * finished executing (after all service wiring has executed).
+ *
+ * NOTE: This API hasn't settled. It may change at any time without warning. Please don't bind to
+ * it unless you absolutely need to
+ *
+ * @unstable
+ *
+ * @package FeatureManagement
+ * @internal
+ */
+final class DynamicConfigRequirement implements Requirement {
+
+	/**
+	 * @var \Config
+	 */
+	private $config;
+
+	/**
+	 * @var string
+	 */
+	private $configName;
+
+	/**
+	 * @var string
+	 */
+	private $requirementName;
+
+	/**
+	 * @param \Config $config
+	 * @param string $configName
+	 * @param string $requirementName The name of the requirement presented to the Feature Manager
+	 */
+	public function __construct( \Config $config, string $configName, string $requirementName ) {
+		$this->config = $config;
+		$this->configName = $configName;
+		$this->requirementName = $requirementName;
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	public function getName() : string {
+		return $this->requirementName;
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	public function isMet() : bool {
+		return (bool)$this->config->get( $this->configName );
+	}
+}
diff --git a/includes/FeatureManagement/TODO.md b/includes/FeatureManagement/TODO.md
index 0279e9f9..017407d2 100644
--- a/includes/FeatureManagement/TODO.md
+++ b/includes/FeatureManagement/TODO.md
@@ -6,28 +6,6 @@ API and associated scaffolding classes (see https://phabricator.wikimedia.org/T2
 https://gerrit.wikimedia.org/r/#/c/mediawiki/skins/Vector/+/572323/). This document aims to list
 the steps required to get from this system to something as powerful as Piotr's.
 
-1. ~~Decide whether "set" is the correct name~~
-2. Add support for sets that utilise contextual information that isn't available at boot time, e.g.
-
-```php
-use Vector\Constants;
-use IContextSource;
-
-$featureManager->registerRequirement( Constants::LOGGED_IN_REQ, function( IContextSource $context ) {
-	$user = $context->getUser();
-
-	return $user
-		&& $user->isSafeToLoad()
-		&& $user->isLoggedIn();
-} );
-
-$featureManager->registerRequirement( Constants::MAINSPACE_REQ, function ( IContextSource $context ) {
-	$title = $context->getTitle();
-
-	return $title && $title->inNamespace( NS_MAIN );
-} );
-```
-
-3. Consider supporing memoization of those requirements (see https://gerrit.wikimedia.org/r/#/c/mediawiki/skins/Vector/+/573626/7/includes/FeatureManagement/FeatureManager.php@68)
-4. Add support for getting all requirements
-5. Add support for getting all features enabled when a requirement is enabled/disabled
+1. Consider supporing memoization of those requirements (see https://gerrit.wikimedia.org/r/#/c/mediawiki/skins/Vector/+/573626/7/includes/FeatureManagement/FeatureManager.php@68)
+2. Add support for getting all requirements
+3. Add support for getting all features enabled when a requirement is enabled/disabled
diff --git a/includes/ServiceWiring.php b/includes/ServiceWiring.php
index 0366cbeb..ba18933c 100644
--- a/includes/ServiceWiring.php
+++ b/includes/ServiceWiring.php
@@ -25,12 +25,22 @@
 use MediaWiki\MediaWikiServices;
 use Vector\Constants;
 use Vector\FeatureManagement\FeatureManager;
+use Vector\FeatureManagement\Requirements\DynamicConfigRequirement;
 
 return [
 	Constants::SERVICE_CONFIG => function ( MediaWikiServices $services ) {
 		return $services->getService( 'ConfigFactory' )->makeConfig( Constants::SKIN_NAME );
 	},
 	Constants::SERVICE_FEATURE_MANAGER => function ( MediaWikiServices $services ) {
-		return new FeatureManager();
+		$requirement = new DynamicConfigRequirement(
+			$services->getMainConfig(),
+			Constants::CONFIG_KEY_FULLY_INITIALISED,
+			Constants::REQUIREMENT_FULLY_INITIALISED
+		);
+
+		$featureManager = new FeatureManager();
+		$featureManager->registerComplexRequirement( $requirement );
+
+		return $featureManager;
 	}
 ];
diff --git a/tests/phpunit/unit/FeatureManagement/Requirements/DynamicConfigRequirementTest.php b/tests/phpunit/unit/FeatureManagement/Requirements/DynamicConfigRequirementTest.php
new file mode 100644
index 00000000..154ebbe4
--- /dev/null
+++ b/tests/phpunit/unit/FeatureManagement/Requirements/DynamicConfigRequirementTest.php
@@ -0,0 +1,74 @@
+<?php
+
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @since 1.35
+ */
+
+namespace Vector\FeatureManagement\Tests;
+
+use Vector\FeatureManagement\Requirements\DynamicConfigRequirement;
+
+/**
+ * @group Vector
+ * @group FeatureManagement
+ * @coversDefaultClass \Vector\FeatureManagement\Requirements\DynamicConfigRequirement
+ */
+class DynamicConfigRequirementTest extends \MediaWikiUnitTestCase {
+
+	/**
+	 * @covers ::isMet
+	 */
+	public function testItFetchesAndReturnsConfigValue() {
+		$config = $this->createMock( \Config::class );
+		$config->expects( $this->once() )
+			->method( 'get' )
+			->with( 'Foo' )
+			->willReturn( true );
+
+		$requirement = new DynamicConfigRequirement( $config, 'Foo', 'Bar' );
+
+		$this->assertTrue( $requirement->isMet() );
+	}
+
+	/**
+	 * @covers ::isMet
+	 */
+	public function testItCastsConfigValue() {
+		$config = new \HashConfig( [
+			'Foo' => new \stdClass(),
+		] );
+
+		$requirement = new DynamicConfigRequirement( $config, 'Foo', 'Bar' );
+
+		$this->assertTrue( $requirement->isMet() );
+	}
+
+	/**
+	 * @covers ::getName
+	 */
+	public function testItReturnsName() {
+		$requirement = new DynamicConfigRequirement(
+			new \HashConfig(),
+			'Foo',
+			'Bar'
+		);
+
+		$this->assertEquals( 'Bar', $requirement->getName() );
+	}
+}