diff --git a/includes/Abstracts/Abstract_Feature.php b/includes/Abstracts/Abstract_Feature.php
index 06eba4a..5c9da20 100644
--- a/includes/Abstracts/Abstract_Feature.php
+++ b/includes/Abstracts/Abstract_Feature.php
@@ -5,6 +5,8 @@
  * @package WordPress\AI\Abstracts
  */
 
+declare( strict_types=1 );
+
 namespace WordPress\AI\Abstracts;
 
 use WordPress\AI\Contracts\Feature;
@@ -24,7 +26,7 @@ abstract class Abstract_Feature implements Feature {
 	 * @since 0.1.0
 	 * @var string
 	 */
-	protected $id;
+	protected string $id;
 
 	/**
 	 * Feature label.
@@ -32,7 +34,7 @@ abstract class Abstract_Feature implements Feature {
 	 * @since 0.1.0
 	 * @var string
 	 */
-	protected $label;
+	protected string $label;
 
 	/**
 	 * Feature description.
@@ -40,7 +42,7 @@ abstract class Abstract_Feature implements Feature {
 	 * @since 0.1.0
 	 * @var string
 	 */
-	protected $description;
+	protected string $description;
 
 	/**
 	 * Whether the feature is enabled.
@@ -48,7 +50,7 @@ abstract class Abstract_Feature implements Feature {
 	 * @since 0.1.0
 	 * @var bool
 	 */
-	private $enabled = true;
+	private bool $enabled = true;
 
 	/**
 	 * Constructor.
diff --git a/includes/Contracts/Feature.php b/includes/Contracts/Feature.php
index 09ea9e0..a5e0640 100644
--- a/includes/Contracts/Feature.php
+++ b/includes/Contracts/Feature.php
@@ -5,6 +5,8 @@
  * @package WordPress\AI\Contracts
  */
 
+declare( strict_types=1 );
+
 namespace WordPress\AI\Contracts;
 
 /**
diff --git a/includes/Exception/Invalid_Feature_Exception.php b/includes/Exception/Invalid_Feature_Exception.php
index 5c9c2f4..c898891 100644
--- a/includes/Exception/Invalid_Feature_Exception.php
+++ b/includes/Exception/Invalid_Feature_Exception.php
@@ -5,6 +5,8 @@
  * @package WordPress\AI\Exception
  */
 
+declare( strict_types=1 );
+
 namespace WordPress\AI\Exception;
 
 use InvalidArgumentException;
diff --git a/includes/Exception/Invalid_Feature_Metadata_Exception.php b/includes/Exception/Invalid_Feature_Metadata_Exception.php
index f984134..894430a 100644
--- a/includes/Exception/Invalid_Feature_Metadata_Exception.php
+++ b/includes/Exception/Invalid_Feature_Metadata_Exception.php
@@ -5,6 +5,8 @@
  * @package WordPress\AI\Exception
  */
 
+declare( strict_types=1 );
+
 namespace WordPress\AI\Exception;
 
 use InvalidArgumentException;
diff --git a/includes/Feature_Loader.php b/includes/Feature_Loader.php
index 14500e3..4d53c9a 100644
--- a/includes/Feature_Loader.php
+++ b/includes/Feature_Loader.php
@@ -5,6 +5,8 @@
  * @package WordPress\AI
  */
 
+declare( strict_types=1 );
+
 namespace WordPress\AI;
 
 use Throwable;
@@ -20,14 +22,14 @@
  *
  * @since 0.1.0
  */
-class Feature_Loader {
+final class Feature_Loader {
 	/**
 	 * Feature registry instance.
 	 *
 	 * @since 0.1.0
 	 * @var \WordPress\AI\Feature_Registry
 	 */
-	private $registry;
+	private \WordPress\AI\Feature_Registry $registry;
 
 	/**
 	 * Whether features have been initialized.
@@ -35,7 +37,7 @@ class Feature_Loader {
 	 * @since 0.1.0
 	 * @var bool
 	 */
-	private $initialized = false;
+	private bool $initialized = false;
 
 	/**
 	 * Constructor.
diff --git a/includes/Feature_Registry.php b/includes/Feature_Registry.php
index 794ba58..a07a49e 100644
--- a/includes/Feature_Registry.php
+++ b/includes/Feature_Registry.php
@@ -5,6 +5,8 @@
  * @package WordPress\AI
  */
 
+declare( strict_types=1 );
+
 namespace WordPress\AI;
 
 use WordPress\AI\Contracts\Feature;
@@ -17,14 +19,14 @@
  *
  * @since 0.1.0
  */
-class Feature_Registry {
+final class Feature_Registry {
 	/**
 	 * Registered features.
 	 *
 	 * @since 0.1.0
 	 * @var \WordPress\AI\Contracts\Feature[]
 	 */
-	private $features = array();
+	private array $features = array();
 
 	/**
 	 * Registers a feature.
diff --git a/includes/Features/Example_Feature/Example_Feature.php b/includes/Features/Example_Feature/Example_Feature.php
index c4ce5aa..a23ff99 100644
--- a/includes/Features/Example_Feature/Example_Feature.php
+++ b/includes/Features/Example_Feature/Example_Feature.php
@@ -5,6 +5,8 @@
  * @package WordPress\AI
  */
 
+declare( strict_types=1 );
+
 namespace WordPress\AI\Features\Example_Feature;
 
 use WordPress\AI\Abstracts\Abstract_Feature;
@@ -16,11 +18,9 @@
  */
 class Example_Feature extends Abstract_Feature {
 	/**
-	 * Loads feature metadata.
+	 * {@inheritDoc}
 	 *
 	 * @since 0.1.0
-	 *
-	 * @return array{id: string, label: string, description: string} Feature metadata.
 	 */
 	protected function load_feature_metadata(): array {
 		return array(
@@ -31,7 +31,7 @@ protected function load_feature_metadata(): array {
 	}
 
 	/**
-	 * Registers the feature hooks.
+	 * {@inheritDoc}
 	 *
 	 * @since 0.1.0
 	 */
diff --git a/includes/bootstrap.php b/includes/bootstrap.php
index 70e6537..17bf051 100644
--- a/includes/bootstrap.php
+++ b/includes/bootstrap.php
@@ -7,6 +7,8 @@
  * @package WordPress\AI
  */
 
+declare( strict_types=1 );
+
 namespace WordPress\AI;
 
 // Exit if accessed directly.