diff --git a/CHANGELOG.md b/CHANGELOG.md
index daa128f..6aed526 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,7 +7,42 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-### TBD
+## [1.1.0] - 2026-05-13
+
+### Added
+
+- `AdminAjax::endpoint()` gains an `$auth_only` parameter; when `true`, the `wp_ajax_nopriv_` hook is not registered, restricting the action to authenticated users only.
+- `AdminAjax::verify_nonce()` static helper — verifies a nonce from `$_POST` and calls `wp_die()` on failure.
+- `WPModelFactory::wrap_models()` and `WPModelFactory::apply_meta_fields()` as base implementations, eliminating duplicated code across all four factory subclasses. `wrap()` is now abstract.
+
+### Changed
+
+- `WPModelFactory::wrap()` is now `abstract` — subclasses that previously relied on the no-op base must implement it explicitly.
+- `WPMeta` interface method signatures updated to use strict PHP 8.1 types (`?string $key`, union return types).
+- `WPTaxonomyTerms` interface method signatures updated to use strict PHP 8.1 types.
+- PHP 8.1 typed properties, parameter types, and return types added throughout the framework.
+- All model classes (`GenericPostModel`, `UserModel`, `TaxonomyModel`, `TaxonomyTermModel`, `CommentModel`) annotated with `#[\AllowDynamicProperties]` for intentional dynamic property use.
+- `gettype()` checks replaced with `instanceof` across all model classes and factories.
+- `isset`/ternary patterns replaced with null coalescing (`??`) throughout.
+
+### Fixed
+
+- `Application::setup_controllers()` collapsed from three separate controller loops into one, eliminating 6 `apply_filters()` calls per controller per request and fixing a correctness bug where filter-replaced controller instances were not persisted back to `$this->controllers`, causing later loops to operate on the original (pre-filter) instance.
+- `REST::handle_callback()` no longer redundantly re-assigns `$this->current_request` and re-calls `set_current_endpoint()` — both were already set by `handle_perm_callback()`, which WordPress always runs first; this eliminates a full endpoint scan on every matched REST request.
+- `EmailView::send()` now correctly returns `false` if any recipient fails when passed an array of addresses; previously the return value of each recursive call was discarded and the method always returned `false` for multi-recipient sends regardless of outcome.
+- `CommentModelFactory`: fixed typo `$commend` → `$comment` (caused undefined variable on lookup failure); `create_comment()` now passes the `$comment` argument; `delete_comment()` now uses `comment_ID`; `update_comment()` captures the return value.
+- `Config::get()` no longer overwrites `$default` before it is used; `glob()` calls fall back to `[]` instead of `false`.
+- `Route`: `REQUEST_URI` sanitised via `sanitize_url(wp_unslash(...))` and parsed with `parse_url()` instead of `strtok()`; match check corrected from `!empty($matches)` to checking `$match` directly.
+- `REST`: `extract()` calls removed and replaced with explicit key access; `_doing_it_wrong()` is now emitted when `permission_callback` is absent, discouraging open endpoints.
+- `EmailView`: `$content_templater->subject` dynamic property assignment replaced — subject is now passed through `$content_params` so it is available inside the email body template.
+- `Templater`: constructor bug where `$this->params['template_slug']` referenced a removed local variable; corrected to `$this->slug`.
+
+### Security
+
+- `REQUEST_URI` in `Route` sanitised with `sanitize_url(wp_unslash(...))` before use.
+- `WP_ENV` in `Config` restricted to `[a-zA-Z0-9_-]` via `preg_replace` to prevent path traversal in config file lookups.
+- `EmailView::shortcodes()` switched from `preg_replace` with `$1`/`$2` backreferences to `preg_replace_callback`, eliminating potential backreference injection via user-controlled param values.
+- `REST` emits `_doing_it_wrong()` when `permission_callback` is not provided, discouraging inadvertently public endpoints.
 
 ## [1.0.0-alpha] - 2024-11-01
 
@@ -16,5 +51,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Initial package release v1.0.0-alpha.
 
 
-[unreleased]: https://github.com/TheCodeCompany/wpmvc/compare/v1.0.0-alpha...HEAD
+[unreleased]: https://github.com/TheCodeCompany/wpmvc/compare/v1.1.0...HEAD
+[1.1.0]: https://github.com/TheCodeCompany/wpmvc/compare/v1.0.0-alpha...v1.1.0
 [1.0.0-alpha]: https://github.com/TheCodeCompany/wpmvc/releases/tag/v1.0.0-alpha
diff --git a/src/Core/Application.php b/src/Core/Application.php
index 9e16bd5..a342105 100644
--- a/src/Core/Application.php
+++ b/src/Core/Application.php
@@ -10,7 +10,6 @@
 namespace WPMVC\Core;
 
 use WPMVC\Library\Config;
-use WPMVC\Library\ControllerSetup;
 use WPMVC\Library\Route;
 use WPMVC\Library\REST;
 use WPMVC\Library\AdminAjax;
@@ -37,28 +36,28 @@ class Application {
 	 *
 	 * @var string
 	 */
-	protected $name = '';
+	protected string $name = '';
 
 	/**
 	 * The root directory of the application.
 	 *
 	 * @var string
 	 */
-	protected $directory = '';
+	protected string $directory = '';
 
 	/**
 	 * All of the controllers defined in the application.
 	 *
 	 * @var array
 	 */
-	protected $controllers = [];
+	protected array $controllers = [];
 
 	/**
 	 * The config helper instance.
 	 *
-	 * @var \WPMVC\Library\Config
+	 * @var Config
 	 */
-	protected $config = null;
+	protected ?Config $config = null;
 
 	/**
 	 * Constructor.
@@ -67,7 +66,7 @@ class Application {
 	 * @param string $directory   The root directory of the application.
 	 * @param array  $controllers All of the applications controllers.
 	 */
-	public function __construct( $name, $directory, $controllers ) {
+	public function __construct( string $name, string $directory, array $controllers ) {
 
 		$this->name        = $name;
 		$this->directory   = $directory;
@@ -84,59 +83,35 @@ public function __construct( $name, $directory, $controllers ) {
 	 *
 	 * @return void
 	 */
-	public function setup_controllers() {
+	public function setup_controllers(): void {
 
 		// Set helper instances.
 		$route = new Route();
 		$rest  = new REST();
 		$ajax  = new AdminAjax();
-		foreach ( $this->controllers as $controller ) {
 
-			/**
-			 * Apply filters to the controller before we set instances.
-			 */
+		foreach ( $this->controllers as $index => $controller ) {
+
 			$controller = apply_filters( 'wpmvc_pre_controller_set_instances', $controller );
 
 			$controller->set_route_instance( $route );
 			$controller->set_rest_instance( $rest );
-			$controller->set_admin_ajax_instance( $ajax ); // TODO: implement and test.
+			$controller->set_admin_ajax_instance( $ajax );
 
-			/**
-			 * Apply filters to the controller after we set instances.
-			 */
 			$controller = apply_filters( 'wpmvc_post_controller_set_instances', $controller );
-		}
-
-		// Set config.
-		foreach ( $this->controllers as $controller ) {
-
-			/**
-			 * Apply filters to the controller before we set the config.
-			 */
 			$controller = apply_filters( 'wpmvc_pre_controller_set_config', $controller );
 
 			$controller->set_config_instance( $this->config );
 
-			/**
-			 * Apply filters to the controller after we set the config.
-			 */
 			$controller = apply_filters( 'wpmvc_post_controller_set_config', $controller );
-		}
-
-		// Set up each controller.
-		foreach ( $this->controllers as $controller ) {
-
-			/**
-			 * Apply filters to the controller before we set it up.
-			 */
 			$controller = apply_filters( 'wpmvc_pre_controller_set_up', $controller );
 
 			$controller->set_up();
 
-			/**
-			 * Apply filters to the controller after we set it up.
-			 */
 			$controller = apply_filters( 'wpmvc_post_controller_set_up', $controller );
+
+			// Write back so filter-replaced instances are persisted for callers.
+			$this->controllers[ $index ] = $controller;
 		}
 	}
 
@@ -145,7 +120,7 @@ public function setup_controllers() {
 	 *
 	 * @return Config
 	 */
-	public function get_config() {
+	public function get_config(): Config {
 
 		return $this->config;
 	}
@@ -155,7 +130,7 @@ public function get_config() {
 	 *
 	 * @return string
 	 */
-	public function get_directory() {
+	public function get_directory(): string {
 
 		return $this->directory;
 	}
@@ -165,7 +140,7 @@ public function get_directory() {
 	 *
 	 * @return string
 	 */
-	public function get_name() {
+	public function get_name(): string {
 
 		return $this->name;
 	}
@@ -175,7 +150,7 @@ public function get_name() {
 	 *
 	 * @return void
 	 */
-	protected function load_config() {
+	protected function load_config(): void {
 
 		$this->config = new Config( $this );
 		$this->config->autoload();
diff --git a/src/Core/Controller.php b/src/Core/Controller.php
index 5f79828..6b6ef71 100644
--- a/src/Core/Controller.php
+++ b/src/Core/Controller.php
@@ -28,12 +28,6 @@
  * ```
  */
 abstract class Controller {
-	/*
-	 * TODO
-	 * If the "app" stuff comes under a different library, then only
-	 * config should be defined in the base controller class.
-	 * All of the other 'helper' instances should be loaded separately.
-	 */
 
 	/**
 	 * The config helper instance.
@@ -41,7 +35,7 @@ abstract class Controller {
 	 *
 	 * @var Config
 	 */
-	protected $config = null;
+	protected ?Config $config = null;
 
 	/**
 	 * Route helper instance.
@@ -49,7 +43,7 @@ abstract class Controller {
 	 *
 	 * @var Route
 	 */
-	protected $route;
+	protected Route $route;
 
 	/**
 	 * REST helper instance.
@@ -57,7 +51,7 @@ abstract class Controller {
 	 *
 	 * @var REST
 	 */
-	protected $rest;
+	protected REST $rest;
 
 	/**
 	 * Admin AJAX helper instance.
@@ -65,7 +59,7 @@ abstract class Controller {
 	 *
 	 * @var AdminAjax
 	 */
-	protected $admin_ajax;
+	protected AdminAjax $admin_ajax;
 
 	/**
 	 * Called automatically at `plugins_loaded`.
@@ -73,14 +67,14 @@ abstract class Controller {
 	 *
 	 * @return void
 	 */
-	abstract public function set_up();
+	abstract public function set_up(): void;
 
 	/**
 	 * Get the Config instance.
 	 *
 	 * @return Config
 	 */
-	public function get_config() {
+	public function get_config(): ?Config {
 		return $this->config;
 	}
 
@@ -89,7 +83,7 @@ public function get_config() {
 	 *
 	 * @return Route
 	 */
-	public function get_route() {
+	public function get_route(): Route {
 		return $this->route;
 	}
 
@@ -98,7 +92,7 @@ public function get_route() {
 	 *
 	 * @return REST
 	 */
-	public function get_rest() {
+	public function get_rest(): REST {
 		return $this->rest;
 	}
 
@@ -107,7 +101,7 @@ public function get_rest() {
 	 *
 	 * @return AdminAjax
 	 */
-	public function get_admin_ajax() {
+	public function get_admin_ajax(): AdminAjax {
 		return $this->admin_ajax;
 	}
 
@@ -118,7 +112,7 @@ public function get_admin_ajax() {
 	 *
 	 * @return void
 	 */
-	public function set_config_instance( Config $config ) {
+	public function set_config_instance( Config $config ): void {
 
 		$this->config = $config;
 	}
@@ -130,7 +124,7 @@ public function set_config_instance( Config $config ) {
 	 *
 	 * @return void
 	 */
-	public function set_route_instance( Route $route ) {
+	public function set_route_instance( Route $route ): void {
 
 		$this->route = $route;
 	}
@@ -142,7 +136,7 @@ public function set_route_instance( Route $route ) {
 	 *
 	 * @return void
 	 */
-	public function set_rest_instance( REST $rest ) {
+	public function set_rest_instance( REST $rest ): void {
 
 		$this->rest = $rest;
 	}
@@ -154,7 +148,7 @@ public function set_rest_instance( REST $rest ) {
 	 *
 	 * @return void
 	 */
-	public function set_admin_ajax_instance( AdminAjax $admin_ajax ) {
+	public function set_admin_ajax_instance( AdminAjax $admin_ajax ): void {
 
 		$this->admin_ajax = $admin_ajax;
 	}
diff --git a/src/Core/View.php b/src/Core/View.php
index be5e2d0..2028356 100644
--- a/src/Core/View.php
+++ b/src/Core/View.php
@@ -19,7 +19,7 @@ abstract class View {
 	 *
 	 * @var array
 	 */
-	protected $params;
+	protected array $params = [];
 
 	/**
 	 * Set a parameter that will be passed to the template.
@@ -28,7 +28,7 @@ abstract class View {
 	 * @param mixed  $value The value of the parameter.
 	 * @return void
 	 */
-	public function set_param( $name, $value ) {
+	public function set_param( string $name, mixed $value ): void {
 		$this->params[ $name ] = $value;
 	}
 
@@ -38,7 +38,7 @@ public function set_param( $name, $value ) {
 	 * @param string $name The name/slug of the parameter.
 	 * @return mixed
 	 */
-	public function get_param( $name ) {
-		return $this->params[ $name ];
+	public function get_param( string $name ): mixed {
+		return $this->params[ $name ] ?? null;
 	}
 }
diff --git a/src/Library/AdminAjax.php b/src/Library/AdminAjax.php
index d7b522e..f33d274 100644
--- a/src/Library/AdminAjax.php
+++ b/src/Library/AdminAjax.php
@@ -16,18 +16,25 @@
  * $ajax->endpoint( 'my_ajax_action', [ $this, 'my_callback' ] );
  */
 class AdminAjax {
-	// TODO: make singleton.
 
 	/**
 	 * Register a new AJAX endpoint.
 	 *
-	 * @param string $action   The ajax action name.
-	 * @param array  $callback The callback for the ajax hook.
+	 * @param string   $action    The ajax action name.
+	 * @param callable $callback  The callback for the ajax hook.
+	 * @param bool     $auth_only When true, only the wp_ajax_ hook is registered so the
+	 *                            endpoint is restricted to logged-in users. Default false
+	 *                            registers both authenticated and unauthenticated hooks.
+	 *
+	 * @return void
 	 */
-	public function endpoint( $action, $callback ) {
+	public function endpoint( string $action, callable $callback, bool $auth_only = false ): void {
 
 		add_action( 'wp_ajax_' . $action, $callback );
-		add_action( 'wp_ajax_nopriv_' . $action, $callback );
+
+		if ( ! $auth_only ) {
+			add_action( 'wp_ajax_nopriv_' . $action, $callback );
+		}
 	}
 
 	/**
@@ -36,21 +43,39 @@ public function endpoint( $action, $callback ) {
 	 * @param string $param   Parameter to get.
 	 * @param mixed  $default Default value (default = '').
 	 *
-	 * @return mixed|string The value for the parameter or the default.
+	 * @return mixed The value for the parameter or the default.
+	 */
+	public static function get_param( string $param, mixed $default = '' ): mixed {
+
+		return $_POST[ $param ] ?? $default; // phpcs:ignore WordPress.Security.NonceVerification,WordPress.Security.ValidatedSanitizedInput
+	}
+
+	/**
+	 * Verify a nonce sent with an AJAX request.
+	 * Call this at the top of any AJAX callback that modifies data.
+	 *
+	 * @param string $action    The nonce action string used when the nonce was created.
+	 * @param string $nonce_key The POST/GET key holding the nonce value. Default '_wpnonce'.
+	 *
+	 * @return void Calls wp_die() with a 403 response on failure.
 	 */
-	public static function get_param( $param, $default = '' ) {
+	public static function verify_nonce( string $action, string $nonce_key = '_wpnonce' ): void {
 
-		$value = isset( $_POST[ $param ] ) ? $_POST[ $param ] : $default; // phpcs:ignore
+		$nonce = isset( $_REQUEST[ $nonce_key ] ) ? sanitize_text_field( wp_unslash( $_REQUEST[ $nonce_key ] ) ) : ''; // phpcs:ignore WordPress.Security.NonceVerification
 
-		return $value;
+		if ( ! wp_verify_nonce( $nonce, $action ) ) {
+			wp_die( esc_html__( 'Security check failed.', 'wpmvc' ), 403 );
+		}
 	}
 
 	/**
 	 * Serves the given array as a JSON response and dies.
 	 *
 	 * @param array $response The response fields.
+	 *
+	 * @return never
 	 */
-	public static function json_resp( array $response ) {
+	public static function json_resp( array $response ): never {
 
 		header( 'Content-Type: application/json' );
 		die( wp_json_encode( $response ) );
diff --git a/src/Library/Config.php b/src/Library/Config.php
index ed7123f..d111d02 100644
--- a/src/Library/Config.php
+++ b/src/Library/Config.php
@@ -9,13 +9,15 @@
 
 namespace WPMVC\Library;
 
+use WPMVC\Core\Application;
+
 /**
  * Application configuration manager.
  * Use like so, in a controller, model or view:
  *  $my_config = $this->config->get( 'my_config' );
  *  echo $my_config['some_value'];
  *  // Shorthand:
- *  echo $this->config->$this->config->get( 'my_config', 'some_value' );
+ *  echo $this->config->get( 'my_config', 'some_value' );
  * All of the application configuration is autoloaded from the /config/ and /config/local/ directories.
  */
 class Config {
@@ -32,22 +34,21 @@ class Config {
 	 *
 	 * @var array
 	 */
-	protected $config = [];
+	protected array $config = [];
 
 	/**
 	 * Application instance this config is for.
 	 *
-	 * @var \WPMVC\Core\Application
+	 * @var Application
 	 */
-	protected $app;
+	protected Application $app;
 
 	/**
 	 * Creates a new config instance for the given application
 	 *
-	 * @param \WPMVC\Core\Application $app Application instance this config is for.
+	 * @param Application $app Application instance this config is for.
 	 */
-	public function __construct( \WPMVC\Core\Application $app ) {
-		// TODO pass name and directory so we could use this is in a theme or something.
+	public function __construct( Application $app ) {
 
 		$this->app = $app;
 	}
@@ -59,28 +60,21 @@ public function __construct( \WPMVC\Core\Application $app ) {
 	 * @param string $key     Options item in the configuration item in the config file.
 	 * @param mixed  $default The default item/value if none is found.
 	 *
-	 * @return array|mixed|string
+	 * @return mixed
 	 */
-	public function get( $name, $key = '', $default = [] ) {
+	public function get( string $name, string $key = '', mixed $default = [] ): mixed {
 
-		$return_value = $default;
+		$config_array = $this->config[ $name ] ?? null;
 
-		// Retrieve the single configuration array.
-		$config_array = [];
-		if ( isset( $this->config[ $name ] ) ) {
-			$config_array = $this->config[ $name ];
+		if ( null === $config_array ) {
+			return $default;
 		}
 
-		// Return entire config array by default.
-		$return_value = $config_array;
-
-		// Return config item if key has been passed to us.
 		if ( ! empty( $key ) ) {
-			$config_scalar = isset( $config_array[ $key ] ) ? $config_array[ $key ] : $default;
-			$return_value  = $config_scalar;
+			return $config_array[ $key ] ?? $default;
 		}
 
-		return $return_value;
+		return $config_array;
 	}
 
 	/**
@@ -88,7 +82,7 @@ public function get( $name, $key = '', $default = [] ) {
 	 *
 	 * @return string
 	 */
-	public function get_app_name() {
+	public function get_app_name(): string {
 
 		return $this->app->get_name();
 	}
@@ -98,15 +92,17 @@ public function get_app_name() {
 	 *
 	 * @return string
 	 */
-	public function get_app_directory() {
+	public function get_app_directory(): string {
 
 		return $this->app->get_directory();
 	}
 
 	/**
 	 * Autoload the given application configuration from disk.
+	 *
+	 * @return void
 	 */
-	public function autoload() {
+	public function autoload(): void {
 
 		$app_config = [];
 		$env_config = [];
@@ -114,7 +110,7 @@ public function autoload() {
 		$dir = $this->app->get_directory();
 
 		// Load the main configuration merging the default variables when required.
-		$config_files = glob( "$dir/config/*.php" );
+		$config_files = glob( "$dir/config/*.php" ) ?: [];
 		foreach ( $config_files as $config_file ) {
 			$config_name                = basename( $config_file, '.php' );
 			$app_config[ $config_name ] = include $config_file;
@@ -124,33 +120,27 @@ public function autoload() {
 		$env_config_glob = "$dir/config/local/*.php";  // By default assume local dev.
 		if ( defined( 'WP_ENV' ) ) {
 
-			$env_config_glob = sprintf(
-				'%s/config/%s/*.php',
-				$dir,
-				WP_ENV
-			);
+			$env_name        = preg_replace( '/[^a-zA-Z0-9_-]/', '', WP_ENV );
+			$env_config_glob = sprintf( '%s/config/%s/*.php', $dir, $env_name );
 
 		}
 
 		// Load each of the environment specific config files.
-		$config_files = glob( $env_config_glob );
+		$config_files = glob( $env_config_glob ) ?: [];
 		foreach ( $config_files as $config_file ) {
 			$config_name                = basename( $config_file, '.php' );
 			$env_config[ $config_name ] = include $config_file;
 		}
 
 		// Merge the app configs with the environment specific overrides.
-		$app_config_keys = array_keys( $app_config );
-		$env_config_keys = array_keys( $env_config );
-		$all_config_keys = array_merge( $app_config_keys, $env_config_keys );
+		$all_config_keys = array_unique( array_merge( array_keys( $app_config ), array_keys( $env_config ) ) );
 
 		foreach ( $all_config_keys as $config_key ) {
 
-			$app_config_value = isset( $app_config[ $config_key ] ) ? $app_config[ $config_key ] : [];
-			$env_config_value = isset( $env_config[ $config_key ] ) ? $env_config[ $config_key ] : [];
+			$app_config_value = $app_config[ $config_key ] ?? [];
+			$env_config_value = $env_config[ $config_key ] ?? [];
 
 			$this->config[ $config_key ] = array_replace_recursive( $app_config_value, $env_config_value );
-
 		}
 	}
 }
diff --git a/src/Library/REST.php b/src/Library/REST.php
index 0c4e377..dc09705 100644
--- a/src/Library/REST.php
+++ b/src/Library/REST.php
@@ -13,12 +13,13 @@
  * Helper class for registering WordPress REST API endpoints.
  * Example:
  *  // Do this in the setup() method of a class
- *  $this->rest->>endpoint(
+ *  $this->rest->endpoint(
  *      [
- *          'namespace' => $config->app( 'name' ), // This should be the app name
+ *          'namespace' => $config->get_app_name(),
  *          'action'    => 'edit/(?P<id>\d+)',
  *          'method'    => \WP_REST_Server::READABLE,
  *          'callback'  => [ $this, 'edit_thing' ],
+ *          'permission_callback' => '__return_true',
  *      ]
  * );
  * This will create an endpoint like this:
@@ -43,31 +44,30 @@
  *  - DELETE - for deleting objects
  */
 class REST {
-	// TODO: make singleton.
 
 	/**
 	 * All of the defined endpoints.
 	 *
 	 * @var array
 	 */
-	protected $endpoints = [];
+	protected array $endpoints = [];
 
 	/**
 	 * The current REST request, if any.
 	 *
-	 * @var array
+	 * @var \WP_REST_Request|null
 	 */
-	protected $current_request = [];
+	protected ?\WP_REST_Request $current_request = null;
 
 	/**
 	 * The current endpoint, if any.
 	 *
 	 * @var array
 	 */
-	protected $current_endpoint = [];
+	protected array $current_endpoint = [];
 
 	/**
-	 * Initialises the AJAX system if needed.
+	 * Initialises the REST helper.
 	 *
 	 * @return void
 	 */
@@ -86,20 +86,23 @@ public function __construct() {
 	 *                    $method The HTTP method.
 	 *                    $callback The callback for the ajax hook.
 	 *                    $permission_callback The permissions callback for the ajax hook.
+	 *
+	 * @return void
 	 */
-	public function endpoint( array $args ) {
-
-		$default_args = [
-			'namespace'           => '',
-			'version'             => 'v1',
-			'action'              => '',
-			'method'              => 'GET',
-			'callback'            => '',
-			'permission_callback' => '',
-			'args'                => [],
-		];
-
-		$args = array_merge( $default_args, $args );
+	public function endpoint( array $args ): void {
+
+		$args = array_merge(
+			[
+				'namespace'           => '',
+				'version'             => 'v1',
+				'action'              => '',
+				'method'              => 'GET',
+				'callback'            => '',
+				'permission_callback' => '',
+				'args'                => [],
+			],
+			$args
+		);
 
 		// Add to the list of endpoints to register.
 		$route                     = $this->build_route( $args );
@@ -109,9 +112,9 @@ public function endpoint( array $args ) {
 	/**
 	 * Returns the WP REST request object for the current endpoint.
 	 *
-	 * @return mixed
+	 * @return \WP_REST_Request|null
 	 */
-	public function get_request() {
+	public function get_request(): ?\WP_REST_Request {
 		return $this->current_request;
 	}
 
@@ -120,26 +123,36 @@ public function get_request() {
 	 *
 	 * @return void
 	 */
-	public function register_endpoints() {
+	public function register_endpoints(): void {
 
 		foreach ( $this->endpoints as $endpoint ) {
-			extract( $endpoint ); // phpcs:ignore
+
+			if ( empty( $endpoint['permission_callback'] ) ) {
+				_doing_it_wrong(
+					__METHOD__,
+					sprintf(
+						/* translators: %s: REST endpoint action */
+						esc_html__( 'REST endpoint "%s" has no permission_callback. Pass an explicit callback or __return_true to allow public access.', 'wpmvc' ),
+						esc_html( $endpoint['action'] )
+					),
+					'1.0.0'
+				);
+			}
 
 			// Build the actual namespace.
-			$namespace = "{$namespace}/{$version}";
+			$namespace = $endpoint['namespace'] . '/' . $endpoint['version'];
 
 			// Register the endpoint.
 			register_rest_route(
 				$namespace,
-				$action,
+				$endpoint['action'],
 				[
-					'methods'             => $method,
+					'methods'             => $endpoint['method'],
 					'callback'            => [ $this, 'handle_callback' ],
 					'permission_callback' => [ $this, 'handle_perm_callback' ],
-					'args'                => $args,
+					'args'                => $endpoint['args'],
 				]
 			);
-
 		}
 	}
 
@@ -148,9 +161,9 @@ public function register_endpoints() {
 	 *
 	 * @param \WP_REST_Request $request The REST endpoint request.
 	 *
-	 * @return boolean
+	 * @return bool
 	 */
-	public function handle_perm_callback( \WP_REST_Request $request ) {
+	public function handle_perm_callback( \WP_REST_Request $request ): bool {
 
 		$allowed = true;  // Default, free for all.
 
@@ -163,14 +176,11 @@ public function handle_perm_callback( \WP_REST_Request $request ) {
 		// Call user callback if exists.
 		if ( ! empty( $this->current_endpoint ) ) {
 
-			$callback = null;
-			if ( isset( $this->current_endpoint['permission_callback'] ) ) {
-				$callback = $this->current_endpoint['permission_callback'];
-			}
+			$callback = $this->current_endpoint['permission_callback'] ?? null;
 
 			if ( ! empty( $callback ) ) {
 
-				$allowed = call_user_func(
+				$allowed = (bool) call_user_func(
 					$callback,
 					$request,
 					$request->get_params()
@@ -189,7 +199,7 @@ public function handle_perm_callback( \WP_REST_Request $request ) {
 	 *
 	 * @return void
 	 */
-	protected function set_current_endpoint( \WP_REST_Request $request ) {
+	protected function set_current_endpoint( \WP_REST_Request $request ): void {
 		$route = $request->get_route();
 
 		foreach ( $this->endpoints as $endpoint ) {
@@ -211,18 +221,12 @@ protected function set_current_endpoint( \WP_REST_Request $request ) {
 	 *
 	 * @param \WP_REST_Request $request The current request.
 	 *
-	 * @return array
+	 * @return mixed
 	 */
-	public function handle_callback( \WP_REST_Request $request ) {
+	public function handle_callback( \WP_REST_Request $request ): mixed {
 
 		$response = [];
 
-		// Save current request.
-		$this->current_request = $request;
-
-		// Set current end point.
-		$this->set_current_endpoint( $request );
-
 		// Call user callback.
 		if ( ! empty( $this->current_endpoint ) ) {
 
@@ -249,13 +253,7 @@ public function handle_callback( \WP_REST_Request $request ) {
 	 *
 	 * @return string
 	 */
-	private static function build_route( array $endpoint ) {
-		$route = '';
-
-		extract( $endpoint ); // phpcs:ignore
-
-		$route = "/{$namespace}/{$version}/{$action}";
-
-		return $route;
+	private static function build_route( array $endpoint ): string {
+		return '/' . $endpoint['namespace'] . '/' . $endpoint['version'] . '/' . $endpoint['action'];
 	}
 }
diff --git a/src/Library/Route.php b/src/Library/Route.php
index 4b06d19..ffea7b4 100644
--- a/src/Library/Route.php
+++ b/src/Library/Route.php
@@ -23,14 +23,13 @@
  * }
  */
 class Route {
-	// TODO: make singleton.
 
 	/**
 	 * The registered routes.
 	 *
 	 * @var array
 	 */
-	protected $routes = [];
+	protected array $routes = [];
 
 	/**
 	 * Set up the routing system.
@@ -53,7 +52,7 @@ public function __construct() {
 	 *
 	 * @return void
 	 */
-	public function add( array $args ) {
+	public function add( array $args ): void {
 
 		// Set defaults so stuff does not break.
 		$args = array_merge(
@@ -74,30 +73,30 @@ public function add( array $args ) {
 	/**
 	 * Handles routing on 'do_parse_request'
 	 *
-	 * @param boolean $continue         Whether to continue processing the request.
-	 * @param \WP     $wp               Current WordPress environment instance.
-	 * @param mixed   $extra_query_vars Extra passed query variables.
+	 * @param bool  $continue         Whether to continue processing the request.
+	 * @param \WP   $wp               Current WordPress environment instance.
+	 * @param mixed $extra_query_vars Extra passed query variables.
 	 *
-	 * @return boolean
+	 * @return bool
 	 */
-	public function handle_routes( $continue, $wp, $extra_query_vars ) {
+	public function handle_routes( bool $continue, \WP $wp, mixed $extra_query_vars ): bool {
 
 		// Get the request path / URI.
-		$request_path = isset( $_SERVER['REQUEST_URI'] ) ? $_SERVER['REQUEST_URI'] : ''; // phpcs:ignore
+		$request_path = isset( $_SERVER['REQUEST_URI'] ) ? sanitize_url( wp_unslash( $_SERVER['REQUEST_URI'] ) ) : ''; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput
+		$request_path = parse_url( $request_path, PHP_URL_PATH ) ?? '';
 		$request_path = trim( $request_path, '/' );
-		$request_path = strtok( $request_path, '?' );
 
 		// Make request path relative to the site path.
 		// This is required for routes to work when WP is installed in a subdirectory.
 
 		$site_url       = get_site_url();
 		$site_url_parts = wp_parse_url( $site_url );
-		$site_url_path  = isset( $site_url_parts['path'] ) ? $site_url_parts['path'] : '/';
+		$site_url_path  = $site_url_parts['path'] ?? '/';
 		$site_url_path  = trim( $site_url_path, '/' );
 
 		$request_path = preg_replace( '{^/?' . $site_url_path . '/?}', '', $request_path );
 
-		// Regsiter each of the routes.
+		// Register each of the routes.
 		foreach ( $this->routes as $route ) {
 			$regex    = $route['regex'];
 			$callback = $route['callback'];
@@ -107,9 +106,9 @@ public function handle_routes( $continue, $wp, $extra_query_vars ) {
 			$match   = preg_match( '{' . $regex . '}', $request_path, $matches );
 
 			// Dispatch route if a hit.
-			if ( ! empty( $matches ) ) {
+			if ( $match ) {
 
-				// Initialsie the admin bar, so we have admin bar access on custom routes!
+				// Initialise the admin bar, so we have admin bar access on custom routes!
 				if ( is_user_logged_in() ) {
 					_wp_admin_bar_init();
 				}
@@ -138,7 +137,7 @@ public function handle_routes( $continue, $wp, $extra_query_vars ) {
 	 *
 	 * @return void
 	 */
-	protected function set_newrelic_transaction( array $route ) {
+	protected function set_newrelic_transaction( array $route ): void {
 
 		$transaction_name = '';
 
diff --git a/src/Library/Templater.php b/src/Library/Templater.php
index 16ac66c..e0cc622 100644
--- a/src/Library/Templater.php
+++ b/src/Library/Templater.php
@@ -53,35 +53,35 @@ class Templater {
 	 *
 	 * @var string
 	 */
-	protected $slug;
+	protected string $slug;
 
 	/**
 	 * Default template directory.
 	 *
 	 * @var string
 	 */
-	protected $dir;
+	protected string $dir;
 
 	/**
 	 * System plugin directory
 	 *
-	 * @var string
+	 * @var string|null
 	 */
-	protected $system_dir;
+	protected ?string $system_dir = null;
 
 	/**
 	 * Subdirectory the templates will live in
 	 *
 	 * @var string
 	 */
-	protected $subdir;
+	protected string $subdir;
 
 	/**
 	 * Template variables.
 	 *
 	 * @var array
 	 */
-	protected $params = [];
+	protected array $params = [];
 
 	/**
 	 * Constructor.
@@ -92,27 +92,13 @@ class Templater {
 	 */
 	public function __construct( array $args ) {
 
-		$slug   = isset( $args['slug'] ) ? $args['slug'] : '';
-		$dir    = isset( $args['dir'] ) ? $args['dir'] : '';
-		$subdir = isset( $args['subdir'] ) ? $args['subdir'] : '';
-		$params = isset( $args['params'] ) ? $args['params'] : '';
-
-		// assert( ! empty( $slug ) );
-		$this->slug = $slug;
-
-		// assert( ! empty( $dir ) );
-		$this->dir = $dir;
-
-		$this->subdir = $subdir;
-
-		if ( empty( $params ) ) {
-			$this->params = [];
-		} else {
-			$this->params = $params;
-		}
+		$this->slug   = $args['slug']   ?? '';
+		$this->dir    = $args['dir']    ?? '';
+		$this->subdir = $args['subdir'] ?? '';
+		$this->params = $args['params'] ?? [];
 
 		// Add in the template slug.
-		$this->params['template_slug'] = $slug;
+		$this->params['template_slug'] = $this->slug;
 	}
 
 	/**
@@ -123,7 +109,7 @@ public function __construct( array $args ) {
 	 *
 	 * @return void
 	 */
-	public function set_param( $name, $value ) {
+	public function set_param( string $name, mixed $value ): void {
 		$this->params[ $name ] = $value;
 	}
 
@@ -134,22 +120,23 @@ public function set_param( $name, $value ) {
 	 *
 	 * @return mixed
 	 */
-	public function get_param( $name ) {
-		return $this->params[ $name ];
+	public function get_param( string $name ): mixed {
+		return $this->params[ $name ] ?? null;
 	}
 
 	/**
 	 * Renders the template.
 	 *
-	 * @param boolean $output Whether to output the rendered template,  otherwise return it as a string.
+	 * @param bool $output Whether to output the rendered template, otherwise return it as a string.
 	 *
-	 * @return false|string
+	 * @return string|false|null String when $output is false; null when $output is true (outputs directly).
 	 */
-	public function render( $output = true ) {
+	public function render( bool $output = true ): string|false|null {
 
 		if ( $output ) {
 
 			$this->render_output();
+			return null;
 
 		} else {
 
@@ -157,14 +144,15 @@ public function render( $output = true ) {
 			$this->render_output();
 
 			return ob_get_clean();
-
 		}
 	}
 
 	/**
 	 * Render the template and outputs the result.
+	 *
+	 * @return void
 	 */
-	protected function render_output() {
+	protected function render_output(): void {
 
 		$name  = $this->slug;
 		$paths = [
@@ -201,16 +189,11 @@ protected function render_output() {
 	 *
 	 * @return void
 	 */
-	public function render_file( $template_file ) {
-
-		// Display missing template is a fatal error.
-		if ( ! file_exists( $template_file ) ) {
-			wp_die( esc_html( "Template does not exist; $template_file" ) );
-		}
+	public function render_file( string $template_file ): void {
 
 		// Extract the given params into the current scope.
-		// NOTE we only do this for backward compat, this shouldn't actualyl be used in new builds.
-		extract( $this->params ); // phpcs:ignore
+		// NOTE we only do this for backward compat, this shouldn't actually be used in new builds.
+		extract( $this->params ); // phpcs:ignore WordPress.PHP.DontExtract
 
 		// Include and execute the template file.
 		include $template_file;
diff --git a/src/Model/CommentModel.php b/src/Model/CommentModel.php
index 84e751c..8dee2cb 100644
--- a/src/Model/CommentModel.php
+++ b/src/Model/CommentModel.php
@@ -13,14 +13,15 @@
  * A model instance which wraps a `WP_Comment` instance.
  * You should extend this class for a comment model type. I.e. for comments attached to a specific CPT.
  */
+#[\AllowDynamicProperties]
 class CommentModel extends WPModel implements WPMeta {
 
 	/**
 	 * Wrapped WP_Comment
 	 *
-	 * @var \WP_Comment
+	 * @var \WP_Comment|null
 	 */
-	protected $comment;
+	protected ?\WP_Comment $comment;
 
 	/**
 	 * CommentModel constructor.
@@ -29,7 +30,7 @@ class CommentModel extends WPModel implements WPMeta {
 	 */
 	public function __construct( $comment = 0 ) {
 
-		if ( 'object' === (string) gettype( $comment ) ) {
+		if ( $comment instanceof \WP_Comment ) {
 			$this->comment = $comment;
 		} else {
 			$this->comment = get_comment( $comment );
@@ -45,14 +46,10 @@ public function __construct( $comment = 0 ) {
 	 * @return int
 	 * @deprecated Use a factory to update a model.
 	 */
-	public function update( array $args ) {
-		$outcome = 0;
+	public function update( array $args ): int|\WP_Error {
+		$args['comment_ID'] = $this->comment->comment_ID;
 
-		$args['ID'] = $this->comment->comment_ID;
-
-		$outcome = wp_update_comment( $args );
-
-		return $outcome;
+		return wp_update_comment( $args );
 	}
 
 	/**
@@ -62,7 +59,7 @@ public function update( array $args ) {
 	 *
 	 * @return mixed
 	 */
-	public function __get( $name ) {
+	public function __get( string $name ): mixed {
 		$value = null;
 
 		if ( property_exists( $this->comment, $name ) ) {
@@ -80,7 +77,7 @@ public function __get( $name ) {
 	 * @param string $name  Field name/slug.
 	 * @param mixed  $value New field value.
 	 */
-	public function __set( $name, $value ) {
+	public function __set( string $name, mixed $value ): void {
 		if ( property_exists( $this->comment, $name ) ) {
 			$this->comment->$name = $value;
 		} else {
@@ -93,7 +90,7 @@ public function __set( $name, $value ) {
 	 *
 	 * @return array|int|mixed|\WP_Comment|null
 	 */
-	public function get_wp_comment() {
+	public function get_wp_comment(): ?\WP_Comment {
 		return $this->comment;
 	}
 
@@ -106,53 +103,45 @@ public function get_wp_comment() {
 	 *
 	 * @return mixed
 	 */
-	public function get_meta( $key = null, $single = true ) {
-		$meta = get_comment_meta( $this->comment->comment_ID, $key, $single );
-
-		return $meta;
+	public function get_meta( ?string $key = null, bool $single = true ): mixed {
+		return get_comment_meta( $this->comment->comment_ID, $key, $single );
 	}
 
 	/**
 	 * Sets the given meta field.
 	 * Uses `update_comment_meta()` under the hood.
 	 *
-	 * @param string $key   The meta key to get for the comment.
+	 * @param string $key   The meta key to set for the comment.
 	 * @param mixed  $value The value to set the meta field to.
 	 *
-	 * @return bool|int
+	 * @return int|bool
 	 */
-	public function set_meta( $key, $value ) {
-		$outcome = update_comment_meta( $this->comment->comment_ID, $key, $value );
-
-		return $outcome;
+	public function set_meta( string $key, mixed $value ): int|bool {
+		return update_comment_meta( $this->comment->comment_ID, $key, $value );
 	}
 
 	/**
 	 * Adds the given meta field.
 	 * Uses `add_comment_meta()` under the hood.
 	 *
-	 * @param string $key   The meta key to get for the comment.
+	 * @param string $key   The meta key to add for the comment.
 	 * @param mixed  $value The value to set the meta field to.
 	 *
-	 * @return bool|int
+	 * @return int|bool
 	 */
-	public function add_meta( $key, $value ) {
-		$outcome = add_comment_meta( $this->comment->comment_ID, $key, $value );
-
-		return $outcome;
+	public function add_meta( string $key, mixed $value ): int|bool {
+		return add_comment_meta( $this->comment->comment_ID, $key, $value );
 	}
 
 	/**
 	 * Deletes the given meta field - delete_comment_meta().
 	 *
-	 * @param string $key   The meta key to get for the comment.
-	 * @param string $value The value to set the meta field to.
+	 * @param string $key   The meta key to delete for the comment.
+	 * @param string $value Optionally limit deletion to entries with this value.
 	 *
 	 * @return bool `false` for failure, `true` for success.
 	 */
-	public function delete_meta( $key, $value = '' ) {
-		$outcome = delete_comment_meta( $this->comment->comment_ID, $key, $value );
-
-		return $outcome;
+	public function delete_meta( string $key, string $value = '' ): bool {
+		return delete_comment_meta( $this->comment->comment_ID, $key, $value );
 	}
 }
diff --git a/src/Model/CommentModelFactory.php b/src/Model/CommentModelFactory.php
index 064153a..9d12b27 100644
--- a/src/Model/CommentModelFactory.php
+++ b/src/Model/CommentModelFactory.php
@@ -27,7 +27,7 @@ class CommentModelFactory extends WPModelFactory {
 	 * @return null|CommentModel
 	 */
 	public function get_by_id( $id ) {
-		$commend = null;
+		$comment = null;
 
 		$wp_comment = get_comment( $id );
 		if ( ! empty( $wp_comment ) ) {
@@ -114,7 +114,7 @@ public function create_comment( $insert_comment_args, $meta_fields = [] ) {
 
 			// Set comment meta data.
 			if ( ! empty( $meta_fields ) ) {
-				$this->set_comment_meta( $meta_fields );
+				$this->set_comment_meta( $comment, $meta_fields );
 			}
 		}
 
@@ -146,7 +146,7 @@ public function update_comment( $comment, $comment_args = [] ) {
 		$outcome = wp_update_comment( $comment_args );
 
 		if ( 1 === $outcome ) {
-			$this->get_by_id( $comment->comment_ID );
+			$updated_comment = $this->get_by_id( $comment->comment_ID );
 		}
 
 		return $updated_comment;
@@ -161,7 +161,7 @@ public function update_comment( $comment, $comment_args = [] ) {
 	 * @return bool.
 	 */
 	public function delete_comment( $comment, $force_delete = false ) {
-		return $this->delete_comment_by_id( $comment->ID, $force_delete );
+		return $this->delete_comment_by_id( $comment->comment_ID, $force_delete );
 	}
 
 	/**
@@ -183,37 +183,7 @@ public function delete_comment_by_id( $comment_id, $force_delete = false ) {
 	 * @param array        $meta_fields The key/value meta data.
 	 */
 	public function set_comment_meta( $comment, $meta_fields ) {
-		foreach ( $meta_fields as $key => $value ) {
-			if ( empty( $value ) ) {
-				$comment->delete_meta( $key );
-			} elseif ( is_array( $value ) ) {
-					$comment->delete_meta( $key );
-
-					// Arrays are added as multiple, separate values.
-				foreach ( $value as $val ) {
-					$comment->add_meta( $key, $val );
-				}
-			} else {
-				$comment->set_meta( $key, $value );
-			}
-		}
-	}
-
-	/**
-	 * Wrap the given WP model instances.
-	 *
-	 * @param array $wp_models WordPress model instances.
-	 *
-	 * @return array
-	 */
-	public function wrap_models( $wp_models ) {
-		$models = [];
-
-		foreach ( $wp_models as $wp_model ) {
-			$models[] = $this->wrap( $wp_model );
-		}
-
-		return $models;
+		$this->apply_meta_fields( $comment, $meta_fields );
 	}
 
 	/**
diff --git a/src/Model/GenericPostModel.php b/src/Model/GenericPostModel.php
index 271e509..0ced15d 100644
--- a/src/Model/GenericPostModel.php
+++ b/src/Model/GenericPostModel.php
@@ -38,6 +38,7 @@
  * @property string $comment_count          Number of comments on post (numeric string)
  * @package wpmvc
  */
+#[\AllowDynamicProperties]
 class GenericPostModel extends WPModel implements WPMeta, WPTaxonomyTerms {
 
 	// Post Fields.
@@ -87,9 +88,9 @@ class GenericPostModel extends WPModel implements WPMeta, WPTaxonomyTerms {
 	/**
 	 * The WordPress post instance. The foundation for instance data.
 	 *
-	 * @var \WP_Post
+	 * @var \WP_Post|null
 	 */
-	protected $post;
+	protected ?\WP_Post $post;
 
 	/**
 	 * GenericPostModel constructor.
@@ -98,8 +99,8 @@ class GenericPostModel extends WPModel implements WPMeta, WPTaxonomyTerms {
 	 */
 	public function __construct( $post = null ) {
 
-		// If an ID was passed, retrieved the post object.
-		if ( 'object' !== (string) gettype( $post ) ) {
+		// If an ID was passed, retrieve the post object.
+		if ( ! ( $post instanceof \WP_Post ) ) {
 			$post = get_post( $post );
 		}
 
@@ -115,14 +116,10 @@ public function __construct( $post = null ) {
 	 * @return int|\WP_Error
 	 * @deprecated Use a model factory to update a post.
 	 */
-	public function update( $args ) {
-		$outcome = 0;
-
+	public function update( array $args ): int|\WP_Error {
 		$args['ID'] = $this->post->ID;
 
-		$outcome = wp_update_post( $args );
-
-		return $outcome;
+		return wp_update_post( $args );
 	}
 
 	/**
@@ -135,7 +132,7 @@ public function update( $args ) {
 	 *                 represents its new state; if it was deleted, $post represents its state before deletion.
 	 * @deprecated Use a model factory to delete a post.
 	 */
-	public function delete_post( $force_delete = true ) {
+	public function delete_post( bool $force_delete = true ): \WP_Post|false|null {
 		return wp_delete_post( $this->ID, $force_delete );
 	}
 
@@ -146,7 +143,7 @@ public function delete_post( $force_delete = true ) {
 	 *
 	 * @return mixed
 	 */
-	public function __get( $name ) {
+	public function __get( string $name ): mixed {
 		$value = null;
 
 		if ( isset( $this->post->$name ) ) {
@@ -164,7 +161,7 @@ public function __get( $name ) {
 	 * @param string $name  Field name/slug.
 	 * @param mixed  $value New field value.
 	 */
-	public function __set( $name, $value ) {
+	public function __set( string $name, mixed $value ): void {
 		if ( isset( $this->post->$name ) ) {
 			$this->post->$name = $value;
 		} else {
@@ -177,7 +174,7 @@ public function __set( $name, $value ) {
 	 *
 	 * @return array|int|\WP_Post|null
 	 */
-	public function get_wp_post() {
+	public function get_wp_post(): ?\WP_Post {
 		return $this->post;
 	}
 
@@ -190,7 +187,7 @@ public function get_wp_post() {
 	 *
 	 * @return mixed
 	 */
-	public function get_meta( $key = null, $single = true ) {
+	public function get_meta( ?string $key = null, bool $single = true ): mixed {
 		return get_post_meta( $this->post->ID, $key, $single );
 	}
 
@@ -203,7 +200,7 @@ public function get_meta( $key = null, $single = true ) {
 	 *
 	 * @return bool|int
 	 */
-	public function set_meta( $key, $value ) {
+	public function set_meta( string $key, mixed $value ): int|bool {
 		return update_post_meta( $this->post->ID, $key, $value );
 	}
 
@@ -216,7 +213,7 @@ public function set_meta( $key, $value ) {
 	 *
 	 * @return false|int
 	 */
-	public function add_meta( $key, $value ) {
+	public function add_meta( string $key, mixed $value ): int|bool {
 		return add_post_meta( $this->post->ID, $key, $value );
 	}
 
@@ -229,7 +226,7 @@ public function add_meta( $key, $value ) {
 	 *
 	 * @return bool `false` for failure, `true` for success.
 	 */
-	public function delete_meta( $key, $value = '' ) {
+	public function delete_meta( string $key, string $value = '' ): bool {
 		return delete_post_meta( $this->post->ID, $key, $value );
 	}
 
@@ -246,7 +243,7 @@ public function delete_meta( $key, $value = '' ) {
 	 * @return array|\WP_Error Array of terms or WP_Error if taxonomy does not
 	 * exist
 	 */
-	public function get_terms( $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT, $args = [] ) {
+	public function get_terms( string $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT, array $args = [] ): array|\WP_Error {
 		return wp_get_post_terms( $this->post->ID, $taxonomy, $args );
 	}
 
@@ -260,8 +257,8 @@ public function get_terms( $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT,
 	 *
 	 * @return array|boolean|\WP_Error|string Array of terms or WP_Error if any issues occurred while processing the request.
 	 */
-	public function set_terms( $terms, $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT, $append = false ) {
-		return wp_set_post_terms( $this->ID, ( is_array( $terms ) ? $terms : [ $terms ] ), $taxonomy, $append );
+	public function set_terms( array|string $terms, string $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT, bool $append = false ): array|bool|\WP_Error {
+		return wp_set_post_terms( $this->ID, is_array( $terms ) ? $terms : [ $terms ], $taxonomy, $append );
 	}
 
 	/**
@@ -271,7 +268,7 @@ public function set_terms( $terms, $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_
 	 *
 	 * @return array|boolean|\WP_Error|string Array of terms or WP_Error if any issues occurred while processing the request.
 	 */
-	public function remove_terms( $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT ) {
+	public function remove_terms( string $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT ): array|bool|\WP_Error {
 		return wp_set_post_terms( $this->ID, [], $taxonomy, false );
 	}
 
@@ -283,7 +280,7 @@ public function remove_terms( $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAU
 	 *
 	 * @return mixed True on success, false or WP_Error on failure.
 	 */
-	public function remove_term( $term_id, $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT ) {
+	public function remove_term( int $term_id, string $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT ): bool|\WP_Error {
 		return wp_remove_object_terms( $this->ID, $term_id, $taxonomy );
 	}
 }
diff --git a/src/Model/GenericPostModelFactory.php b/src/Model/GenericPostModelFactory.php
index 4dae1b8..3a27289 100644
--- a/src/Model/GenericPostModelFactory.php
+++ b/src/Model/GenericPostModelFactory.php
@@ -362,37 +362,7 @@ public function delete_post_by_id( $post_id, $force_delete = false ) {
 	 * @param array            $meta_fields The key/value meta data.
 	 */
 	public function set_post_meta( $post, $meta_fields ) {
-		foreach ( $meta_fields as $key => $value ) {
-			if ( empty( $value ) ) {
-				$post->delete_meta( $key );
-			} elseif ( is_array( $value ) ) {
-					$post->delete_meta( $key );
-
-					// Arrays will be added as multiple, separate values.
-				foreach ( $value as $val ) {
-					$post->add_meta( $key, $val );
-				}
-			} else {
-				$post->set_meta( $key, $value );
-			}
-		}
-	}
-
-	/**
-	 * Wrap the given WP model instances.
-	 *
-	 * @param array $wp_models WordPress model instances.
-	 *
-	 * @return array
-	 */
-	public function wrap_models( $wp_models ) {
-		$models = array();
-
-		foreach ( $wp_models as $wp_model ) {
-			$models[] = $this->wrap( $wp_model );
-		}
-
-		return $models;
+		$this->apply_meta_fields( $post, $meta_fields );
 	}
 
 	/**
diff --git a/src/Model/PageModelFactory.php b/src/Model/PageModelFactory.php
index d823682..317569e 100644
--- a/src/Model/PageModelFactory.php
+++ b/src/Model/PageModelFactory.php
@@ -33,7 +33,6 @@ public function get_post_type() {
 	 * @return GenericPostModel|PageModel
 	 */
 	public function wrap( $post ) {
-		// assert( ! empty( $post ) );
 
 		return new PageModel( $post );
 	}
diff --git a/src/Model/PostModelFactory.php b/src/Model/PostModelFactory.php
index 11d4f58..070c6c4 100644
--- a/src/Model/PostModelFactory.php
+++ b/src/Model/PostModelFactory.php
@@ -35,7 +35,6 @@ public function get_post_type() {
 	 * @return GenericPostModel|PostModel
 	 */
 	public function wrap( $post ) {
-		// assert( ! empty( $post ) );
 
 		return new PostModel( $post );
 	}
diff --git a/src/Model/TaxonomyModel.php b/src/Model/TaxonomyModel.php
index 7352c3c..edb50da 100644
--- a/src/Model/TaxonomyModel.php
+++ b/src/Model/TaxonomyModel.php
@@ -14,14 +14,15 @@
  *
  * @package wpmvc
  */
+#[\AllowDynamicProperties]
 class TaxonomyModel extends WPModel {
 
 	/**
 	 * The WP_Taxonomy instance for the model.
 	 *
-	 * @var \WP_Taxonomy
+	 * @var \WP_Taxonomy|false
 	 */
-	protected $taxonomy;
+	protected \WP_Taxonomy|false $taxonomy;
 
 	/**
 	 * TaxonomyModel constructor.
@@ -29,9 +30,8 @@ class TaxonomyModel extends WPModel {
 	 * @param null|\WP_Taxonomy|string $taxonomy The taxonomy instance.
 	 */
 	public function __construct( $taxonomy = null ) {
-		// assert( ! empty( $taxonomy ) );
 
-		if ( 'object' === (string) gettype( $taxonomy ) ) {
+		if ( $taxonomy instanceof \WP_Taxonomy ) {
 			$this->taxonomy = $taxonomy;
 		} else {
 			$this->taxonomy = get_taxonomy( $taxonomy );
@@ -45,7 +45,7 @@ public function __construct( $taxonomy = null ) {
 	 *
 	 * @return mixed
 	 */
-	public function __get( $name ) {
+	public function __get( string $name ): mixed {
 		$value = null;
 
 		if ( property_exists( $this->taxonomy, $name ) ) {
@@ -63,7 +63,7 @@ public function __get( $name ) {
 	 * @param string $name  Field name/slug.
 	 * @param mixed  $value New field value.
 	 */
-	public function __set( $name, $value ) {
+	public function __set( string $name, mixed $value ): void {
 		if ( property_exists( $this->taxonomy, $name ) ) {
 			$this->taxonomy->$name = $value;
 		} else {
@@ -76,7 +76,7 @@ public function __set( $name, $value ) {
 	 *
 	 * @return bool|false|string|\WP_Taxonomy
 	 */
-	public function get_wp_taxonomy() {
+	public function get_wp_taxonomy(): \WP_Taxonomy|false {
 		return $this->taxonomy;
 	}
 }
diff --git a/src/Model/TaxonomyModelFactory.php b/src/Model/TaxonomyModelFactory.php
index ea10b4c..e88a87e 100644
--- a/src/Model/TaxonomyModelFactory.php
+++ b/src/Model/TaxonomyModelFactory.php
@@ -23,10 +23,10 @@ class TaxonomyModelFactory extends WPModelFactory {
 	 *
 	 * @return TaxonomyModel|null
 	 */
-	public function get_by_name( $name ) {
+	public function get_by_name( string $name ): ?TaxonomyModel {
 		$taxonomy = null;
 
-		// Get the WP_Taxonomy object with the given name..
+		// Get the WP_Taxonomy object with the given name.
 		$wp_taxonomy = get_taxonomy( $name );
 
 		if ( ! empty( $wp_taxonomy ) ) {
@@ -36,14 +36,7 @@ public function get_by_name( $name ) {
 		return $taxonomy;
 	}
 
-	/*
-	 * TODO
-	 * - Could implement register_taxonomy functionality.
-	 * - Would also open up register_post_type functionality.
-	 * -- This should be implemented in a separate module, outside of core MVC.
-	 */
-
-	public function wrap( $taxonomy ) {
+	public function wrap( mixed $taxonomy ): TaxonomyModel {
 		return new TaxonomyModel( $taxonomy );
 	}
 }
diff --git a/src/Model/TaxonomyTermModel.php b/src/Model/TaxonomyTermModel.php
index a802f97..03ee3b3 100644
--- a/src/Model/TaxonomyTermModel.php
+++ b/src/Model/TaxonomyTermModel.php
@@ -25,6 +25,7 @@
  * @property string $filter
  * @package wpmvc
  */
+#[\AllowDynamicProperties]
 class TaxonomyTermModel extends WPModel implements WPMeta {
 
 	const TAXONOMY_NAME_POST_TAG = 'post_tag';
@@ -36,9 +37,9 @@ class TaxonomyTermModel extends WPModel implements WPMeta {
 	/**
 	 * The term associated with the model instance.
 	 *
-	 * @var array|int|object|\WP_Error|\WP_Term|null
+	 * @var \WP_Term|\WP_Error|null
 	 */
-	protected $term;
+	protected \WP_Term|\WP_Error|null $term;
 
 	/**
 	 * TaxonomyTermModel constructor.
@@ -46,9 +47,8 @@ class TaxonomyTermModel extends WPModel implements WPMeta {
 	 * @param int|\WP_Term $term The term to wrap. Term ID is accepted but discouraged.
 	 */
 	public function __construct( $term = 0 ) {
-		// assert( ! empty( $term ) );
 
-		if ( 'object' === (string) gettype( $term ) ) {
+		if ( $term instanceof \WP_Term ) {
 			$this->term = $term;
 		} else {
 			$this->term = get_term( $term );
@@ -62,7 +62,7 @@ public function __construct( $term = 0 ) {
 	 *
 	 * @return mixed
 	 */
-	public function __get( $name ) {
+	public function __get( string $name ): mixed {
 		$value = null;
 
 		if ( isset( $this->term->$name ) ) {
@@ -80,7 +80,7 @@ public function __get( $name ) {
 	 * @param string $name  Field name/slug.
 	 * @param mixed  $value New field value.
 	 */
-	public function __set( $name, $value ) {
+	public function __set( string $name, mixed $value ): void {
 		if ( isset( $this->term->$name ) ) {
 			$this->term->$name = $value;
 		} else {
@@ -93,7 +93,7 @@ public function __set( $name, $value ) {
 	 *
 	 * @return array|int|object|\WP_Error|\WP_Term|null
 	 */
-	public function get_wp_term() {
+	public function get_wp_term(): \WP_Term|\WP_Error|null {
 		return $this->term;
 	}
 
@@ -105,8 +105,7 @@ public function get_wp_term() {
 	 * @return array|int|object|\WP_Error|\WP_Term|null
 	 * @deprecated Use a factory to update a model.
 	 */
-	public function update( $args ) {
-		// assert( ! empty( $args ) );
+	public function update( array $args ): array|\WP_Error {
 
 		$term_id  = $this->term->term_id;
 		$taxonomy = $this->term->taxonomy;
@@ -122,39 +121,44 @@ public function update( $args ) {
 	 *
 	 * @return mixed
 	 */
-	public function get_meta( $key = null, $single = true ) {
+	public function get_meta( ?string $key = null, bool $single = true ): mixed {
 		return get_term_meta( $this->term->term_id, $key, $single );
 	}
 
 	/**
 	 * Sets the given meta field - update_term_meta().
 	 *
-	 * @param string $key   The meta key to get for the post.
+	 * @param string $key   The meta key to set for the term.
 	 * @param mixed  $value The value to set the meta field to.
+	 *
+	 * @return int|bool
 	 */
-	public function set_meta( $key, $value ) {
+	public function set_meta( string $key, mixed $value ): int|bool {
 		return update_term_meta( $this->term->term_id, $key, $value );
 	}
 
 	/**
 	 * Adds the given meta field - add_term_meta().
 	 *
-	 * @param string $key   The meta key to get for the term.
-	 * @param mixed  $value The value to set the meta field to.
+	 * @param string $key    The meta key to add for the term.
+	 * @param mixed  $value  The value to set the meta field to.
+	 * @param bool   $unique Whether the meta key should be unique. Default false.
+	 *
+	 * @return int|bool
 	 */
-	public function add_meta( $key, $value, $unique = false ) {
+	public function add_meta( string $key, mixed $value, bool $unique = false ): int|bool {
 		return add_term_meta( $this->term->term_id, $key, $value, $unique );
 	}
 
 	/**
 	 * Deletes the given meta field - delete_term_meta().
 	 *
-	 * @param string $key   The meta key to get for the term.
-	 * @param string $value The value to set the meta field to.
+	 * @param string $key   The meta key to delete for the term.
+	 * @param string $value Optionally limit deletion to entries with this value.
 	 *
 	 * @return bool False for failure. True for success.
 	 */
-	public function delete_meta( $key, $value = '' ) {
+	public function delete_meta( string $key, string $value = '' ): bool {
 		return delete_term_meta( $this->term->term_id, $key, $value );
 	}
 }
diff --git a/src/Model/TaxonomyTermModelFactory.php b/src/Model/TaxonomyTermModelFactory.php
index 0347e10..f964d6e 100644
--- a/src/Model/TaxonomyTermModelFactory.php
+++ b/src/Model/TaxonomyTermModelFactory.php
@@ -351,37 +351,7 @@ public function delete_term_by_id( $term_id, $taxonomy, $args = [] ) {
 	 * @param array             $meta_fields The key/value meta data.
 	 */
 	public function set_term_meta( $term, $meta_fields ) {
-		foreach ( $meta_fields as $key => $value ) {
-			if ( empty( $value ) ) {
-				$term->delete_meta( $key );
-			} elseif ( is_array( $value ) ) {
-					$term->delete_meta( $key );
-
-					// Arrays will be added as multiple, separate values.
-				foreach ( $value as $val ) {
-					$term->add_meta( $key, $val );
-				}
-			} else {
-				$term->set_meta( $key, $value );
-			}
-		}
-	}
-
-	/**
-	 * Wrap the given WP model instances.
-	 *
-	 * @param array $wp_models WordPress model instances.
-	 *
-	 * @return array
-	 */
-	public function wrap_models( $wp_models ) {
-		$models = [];
-
-		foreach ( $wp_models as $wp_model ) {
-			$models[] = $this->wrap( $wp_model );
-		}
-
-		return $models;
+		$this->apply_meta_fields( $term, $meta_fields );
 	}
 
 	/**
diff --git a/src/Model/UserModel.php b/src/Model/UserModel.php
index bb6796b..1b221c1 100644
--- a/src/Model/UserModel.php
+++ b/src/Model/UserModel.php
@@ -35,6 +35,7 @@
  * @property string $locale
  *                         TODO document the user properties.
  */
+#[\AllowDynamicProperties]
 class UserModel extends WPModel implements WPMeta {
 
 	const FIELD_USER_LOGIN = 'user_login';
@@ -45,9 +46,9 @@ class UserModel extends WPModel implements WPMeta {
 	/**
 	 * The backing WP_User object.
 	 *
-	 * @var bool|\WP_User
+	 * @var \WP_User|false
 	 */
-	protected $user;
+	protected \WP_User|false $user;
 
 	/**
 	 * UserModel constructor.
@@ -55,9 +56,8 @@ class UserModel extends WPModel implements WPMeta {
 	 * @param \WP_User|int $user User object or ID. Use of ID is discouraged.
 	 */
 	public function __construct( $user = 0 ) {
-		// assert( ! empty( $user ) );
 
-		if ( 'object' === (string) gettype( $user ) ) {
+		if ( $user instanceof \WP_User ) {
 			$this->user = $user;
 		} else {
 			$this->user = get_user_by( 'id', $user );
@@ -71,7 +71,7 @@ public function __construct( $user = 0 ) {
 	 *
 	 * @return mixed
 	 */
-	public function __get( $name ) {
+	public function __get( string $name ): mixed {
 		$value = null;
 
 		if ( isset( $this->user->$name ) ) {
@@ -89,7 +89,7 @@ public function __get( $name ) {
 	 * @param string $name  Field name/slug.
 	 * @param mixed  $value New field value.
 	 */
-	public function __set( $name, $value ) {
+	public function __set( string $name, mixed $value ): void {
 		if ( isset( $this->user->$name ) ) {
 			$this->user->$name = $value;
 		} else {
@@ -105,7 +105,7 @@ public function __set( $name, $value ) {
 	 *
 	 * @return mixed
 	 */
-	public function __call( $name, $args ) {
+	public function __call( string $name, array $args ): mixed {
 		$return = null;
 
 		if ( method_exists( $this->user, $name ) ) {
@@ -122,7 +122,7 @@ public function __call( $name, $args ) {
 	 *
 	 * @return bool|int|\WP_User
 	 */
-	public function get_wp_user() {
+	public function get_wp_user(): \WP_User|false {
 		return $this->user;
 	}
 
@@ -134,8 +134,7 @@ public function get_wp_user() {
 	 * @return int|\WP_Error
 	 * @deprecated Use a factory to update a model.
 	 */
-	public function update( $args ) {
-		// assert( ! empty( $args ) );
+	public function update( array $args ): int|\WP_Error {
 		$args['ID'] = $this->user->ID;
 
 		return wp_update_user( $args );
@@ -149,7 +148,7 @@ public function update( $args ) {
 	 *
 	 * @return mixed
 	 */
-	public function get_meta( $key = null, $single = true ) {
+	public function get_meta( ?string $key = null, bool $single = true ): mixed {
 		return get_user_meta( $this->user->ID, $key, $single );
 	}
 
@@ -161,8 +160,7 @@ public function get_meta( $key = null, $single = true ) {
 	 *
 	 * @return bool|int
 	 */
-	public function set_meta( $key, $value ) {
-		// assert( ! empty( $key ) );
+	public function set_meta( string $key, mixed $value ): int|bool {
 
 		return update_user_meta( $this->user->ID, $key, $value );
 	}
@@ -176,8 +174,7 @@ public function set_meta( $key, $value ) {
 	 *
 	 * @return false|int
 	 */
-	public function add_meta( $key, $value, $unique = false ) {
-		// assert( ! empty( $key ) );
+	public function add_meta( string $key, mixed $value, bool $unique = false ): int|bool {
 
 		return add_user_meta( $this->user->ID, $key, $value, $unique );
 	}
@@ -190,8 +187,7 @@ public function add_meta( $key, $value, $unique = false ) {
 	 *
 	 * @return bool False for failure. True for success.
 	 */
-	public function delete_meta( $key, $value = '' ) {
-		// assert( ! empty( $key ) );
+	public function delete_meta( string $key, string $value = '' ): bool {
 
 		return delete_user_meta( $this->user->ID, $key, $value );
 	}
@@ -201,7 +197,7 @@ public function delete_meta( $key, $value = '' ) {
 	 *
 	 * @param string $role Role to pass to the set_role call on $this->user.
 	 */
-	public function set_role( $role ) {
+	public function set_role( string $role ): void {
 		$this->user->set_role( $role );
 	}
 }
diff --git a/src/Model/UserModelFactory.php b/src/Model/UserModelFactory.php
index b9c516e..26c25e1 100644
--- a/src/Model/UserModelFactory.php
+++ b/src/Model/UserModelFactory.php
@@ -175,10 +175,10 @@ public function convert_models_to_output( $users, $output = self::OUTPUT_DEFAULT
 	/**
 	 * Converts the WP User object into the desired output.
 	 *
-	 * @param \WP_Post $user   The user object to convert.
+	 * @param \WP_User $user   The user object to convert.
 	 * @param string   $output Output type for return value.
 	 *
-	 * @return UserModel|null post in the desired output.
+	 * @return UserModel|int|null User in the desired output.
 	 */
 	public function convert_model_to_output( $user, $output = self::OUTPUT_DEFAULT ) {
 		$converted_user = null;
@@ -302,20 +302,7 @@ public function update_user( $user, $user_data = [] ) {
 	 * @param array     $meta_fields The key/value meta data.
 	 */
 	public function set_user_meta( $user, $meta_fields ) {
-		foreach ( $meta_fields as $key => $value ) {
-			if ( empty( $value ) ) {
-				$user->delete_meta( $key );
-			} elseif ( is_array( $value ) ) {
-					$user->delete_meta( $key );
-
-					// Arrays will be added as multiple, separate values.
-				foreach ( $value as $val ) {
-					$user->add_meta( $key, $val );
-				}
-			} else {
-				$user->set_meta( $key, $value );
-			}
-		}
+		$this->apply_meta_fields( $user, $meta_fields );
 	}
 
 	/**
@@ -342,23 +329,6 @@ public function delete_user_by_id( $user_id, $reassign = null ) {
 		return wp_delete_user( $user_id, $reassign );
 	}
 
-	/**
-	 * Wrap the given WP model instances.
-	 *
-	 * @param array $wp_models WordPress model instances.
-	 *
-	 * @return array
-	 */
-	public function wrap_models( $wp_models ) {
-		$models = [];
-
-		foreach ( $wp_models as $wp_model ) {
-			$models[] = $this->wrap( $wp_model );
-		}
-
-		return $models;
-	}
-
 	/**
 	 * The role the factory works with. If empty, no specific role is used.
 	 *
diff --git a/src/Model/WPMeta.php b/src/Model/WPMeta.php
index 13526c7..c96fe9e 100644
--- a/src/Model/WPMeta.php
+++ b/src/Model/WPMeta.php
@@ -18,38 +18,43 @@ interface WPMeta {
 	/**
 	 * Returns the given meta field.
 	 *
-	 * @param string $key The meta key to get for the object, null to return all
-	 * meta fields. Default `null`.
-	 * @param bool   $single Whether to get a single value, or array of all
-	 * meta. Default `true`.
+	 * @param string|null $key    The meta key to get for the object, null to return all
+	 *                            meta fields. Default `null`.
+	 * @param bool        $single Whether to get a single value, or array of all
+	 *                            meta. Default `true`.
+	 *
+	 * @return mixed
 	 */
-	public function get_meta( $key = null, $single = true );
+	public function get_meta( ?string $key = null, bool $single = true ): mixed;
 
 	/**
 	 * Sets the given meta field.
 	 *
-	 * @param string $key The meta key to get for the object.
+	 * @param string $key   The meta key to set for the object.
 	 * @param mixed  $value The value to set the meta field to.
+	 *
 	 * @return int|bool Meta ID if the key didn't exist, true on successful
-	 * update, false on failure.
+	 *                  update, false on failure.
 	 */
-	public function set_meta( $key, $value );
+	public function set_meta( string $key, mixed $value ): int|bool;
 
 	/**
 	 * Adds the given meta field.
 	 *
-	 * @param string $key The meta key to get for the object.
+	 * @param string $key   The meta key to add for the object.
 	 * @param mixed  $value The value to set the meta field to.
+	 *
 	 * @return int|bool Meta ID on success, false on failure.
 	 */
-	public function add_meta( $key, $value );
+	public function add_meta( string $key, mixed $value ): int|bool;
 
 	/**
 	 * Deletes the given meta field.
 	 *
-	 * @param string $key The meta key to get for the object.
-	 * @param string $value The value to set the meta field to.
+	 * @param string $key   The meta key to delete for the object.
+	 * @param string $value Optionally limit deletion to entries with this value.
+	 *
 	 * @return bool False for failure. True for success.
 	 */
-	public function delete_meta( $key, $value = '' );
+	public function delete_meta( string $key, string $value = '' ): bool;
 }
diff --git a/src/Model/WPModelFactory.php b/src/Model/WPModelFactory.php
index 8c75163..1fd2242 100644
--- a/src/Model/WPModelFactory.php
+++ b/src/Model/WPModelFactory.php
@@ -16,6 +16,55 @@
  *
  * @package wpmvc
  */
-class WPModelFactory extends ModelFactory {
+abstract class WPModelFactory extends ModelFactory {
 
+	/**
+	 * Wrap an array of WP model objects using this factory's wrap() method.
+	 *
+	 * @param array $wp_models WordPress model objects to wrap.
+	 *
+	 * @return array
+	 */
+	public function wrap_models( array $wp_models ): array {
+		$models = [];
+
+		foreach ( $wp_models as $wp_model ) {
+			$models[] = $this->wrap( $wp_model );
+		}
+
+		return $models;
+	}
+
+	/**
+	 * Apply an array of meta key/value pairs to a model that implements WPMeta.
+	 * Empty values delete the key; array values are stored as multiple separate entries.
+	 *
+	 * @param WPMeta $model       The model to update meta for.
+	 * @param array  $meta_fields Key/value meta data.
+	 *
+	 * @return void
+	 */
+	protected function apply_meta_fields( WPMeta $model, array $meta_fields ): void {
+		foreach ( $meta_fields as $key => $value ) {
+			if ( empty( $value ) ) {
+				$model->delete_meta( $key );
+			} elseif ( is_array( $value ) ) {
+				$model->delete_meta( $key );
+				foreach ( $value as $val ) {
+					$model->add_meta( $key, $val );
+				}
+			} else {
+				$model->set_meta( $key, $value );
+			}
+		}
+	}
+
+	/**
+	 * Wrap a single model object. Must be overridden by child factories.
+	 *
+	 * @param mixed $model The model object to wrap.
+	 *
+	 * @return mixed
+	 */
+	abstract public function wrap( mixed $model ): mixed;
 }
diff --git a/src/Model/WPTaxonomyTerms.php b/src/Model/WPTaxonomyTerms.php
index b7b68c8..6b0177c 100644
--- a/src/Model/WPTaxonomyTerms.php
+++ b/src/Model/WPTaxonomyTerms.php
@@ -24,39 +24,37 @@ interface WPTaxonomyTerms {
 	 *                         Defaults to post_tag.
 	 * @param array  $args     Args to pass to `wp_get_post_terms()`.
 	 *
-	 * @return array|\WP_Error Array of terms or WP_Error if taxonomy does not
-	 * exist
+	 * @return array|\WP_Error Array of terms or WP_Error if taxonomy does not exist.
 	 */
-	public function get_terms( $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT, $args = [] );
+	public function get_terms( string $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT, array $args = [] ): array|\WP_Error;
 
 	/**
 	 * Adds new terms to the object.
 	 *
-	 * @param array   $terms    List of terms. Can be an array or a comma separated string. If you want to enter terms of a hierarchical taxonomy like
-	 *                          categories, then use IDs. If you want to add non-hierarchical terms like tags, then use names.
-	 * @param string  $taxonomy Possible values for example: 'category', 'post_tag', 'taxonomy slug'.
-	 * @param boolean $append   If true, tags will be appended to the object. If false, tags will replace existing tags.
+	 * @param array|string $terms    List of terms. Can be an array or a comma separated string.
+	 * @param string       $taxonomy Possible values for example: 'category', 'post_tag', 'taxonomy slug'.
+	 * @param bool         $append   If true, terms will be appended. If false, they will replace existing terms.
 	 *
-	 * @return array|boolean|\WP_Error|string Array of terms or WP_Error if any issues occurred while processing the request.
+	 * @return array|bool|\WP_Error Array of term IDs or WP_Error if any issues occurred.
 	 */
-	public function set_terms( $terms, $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT, $append = false );
+	public function set_terms( array|string $terms, string $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT, bool $append = false ): array|bool|\WP_Error;
 
 	/**
 	 * Removes all of the terms attached to this object from the provided taxonomy.
 	 *
 	 * @param string $taxonomy The taxonomy to remove all of the terms for.
 	 *
-	 * @return array|boolean|\WP_Error|string Array of terms or WP_Error if any issues occurred while processing the request.
+	 * @return array|bool|\WP_Error Array of term IDs or WP_Error if any issues occurred.
 	 */
-	public function remove_terms( $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT );
+	public function remove_terms( string $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT ): array|bool|\WP_Error;
 
 	/**
 	 * Removes a term from this object.
 	 *
-	 * @param integer $term_id  The ID for the term that needs to be removed.
-	 * @param string  $taxonomy The taxonomy name.
+	 * @param int    $term_id  The ID for the term that needs to be removed.
+	 * @param string $taxonomy The taxonomy name.
 	 *
-	 * @return mixed True on success, false or WP_Error on failure.
+	 * @return bool|\WP_Error True on success, false or WP_Error on failure.
 	 */
-	public function remove_term( $term_id, $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT );
+	public function remove_term( int $term_id, string $taxonomy = TaxonomyTermModel::TAXONOMY_NAME_DEFAULT ): bool|\WP_Error;
 }
diff --git a/src/View/EmailView.php b/src/View/EmailView.php
index 6f713e7..b8c12cc 100644
--- a/src/View/EmailView.php
+++ b/src/View/EmailView.php
@@ -36,28 +36,35 @@ class EmailView extends View {
 	 *
 	 * @var Config
 	 */
-	protected $config;
+	protected Config $config;
 
 	/**
 	 * The email template file.
 	 *
 	 * @var string
 	 */
-	protected $template;
+	protected string $template;
 
 	/**
 	 * Email headers.
 	 *
 	 * @var array
 	 */
-	protected $headers = [];
+	protected array $headers = [];
 
 	/**
 	 * Files to attach.
 	 *
 	 * @var array
 	 */
-	protected $attachments = [];
+	protected array $attachments = [];
+
+	/**
+	 * Whether the mail filters have been registered yet.
+	 *
+	 * @var bool
+	 */
+	private static bool $filters_registered = false;
 
 	/**
 	 * Constructor.
@@ -65,25 +72,29 @@ class EmailView extends View {
 	 * @param Config $config   App configuration object.
 	 * @param string $template The email template file.
 	 */
-	public function __construct( Config $config, $template ) {
+	public function __construct( Config $config, string $template ) {
 
 		$this->config   = $config;
 		$this->template = $template;
 
-		// Force html content type for emails.
-		add_filter(
-			'wp_mail_content_type',
-			function () {
-				return 'text/html';
-			}
-		);
+		self::register_mail_filters();
+	}
 
-		add_filter(
-			'wp_mail_charset',
-			function () {
-				return 'UTF-8';
-			}
-		);
+	/**
+	 * Register wp_mail filters once per process, regardless of how many EmailView instances are created.
+	 *
+	 * @return void
+	 */
+	private static function register_mail_filters(): void {
+
+		if ( self::$filters_registered ) {
+			return;
+		}
+
+		add_filter( 'wp_mail_content_type', static function () { return 'text/html'; } );
+		add_filter( 'wp_mail_charset',      static function () { return 'UTF-8'; } );
+
+		self::$filters_registered = true;
 	}
 
 	/**
@@ -91,9 +102,8 @@ function () {
 	 *
 	 * @param string $filename Absolute path of the file to attach.
 	 */
-	public function attach( $filename ) {
+	public function attach( string $filename ): void {
 
-		// assert( file_exists( $filename ) );
 
 		$this->attachments[] = $filename;
 	}
@@ -105,16 +115,18 @@ public function attach( $filename ) {
 	 *
 	 * @return boolean Whether the email was sent correctly.  NOTE does not mean that it was received properly.
 	 */
-	public function send( $to ) {
+	public function send( string|array $to ): bool {
 		$success = false;
 
-		// assert( ! empty( $to ) );
 
 		// Recurse if the to field is an array of email addresses.
 		if ( is_array( $to ) ) {
 
+			$success = true;
 			foreach ( $to as $recipient ) {
-				$this->send( $recipient );
+				if ( ! $this->send( $recipient ) ) {
+					$success = false;
+				}
 			}
 
 			return $success;
@@ -132,16 +144,17 @@ public function send( $to ) {
 		$subject = $subject_templater->render( false );
 
 		// Build the email content template.
+		$content_params            = $this->params;
+		$content_params['subject'] = $subject;
+
 		$content_templater = new Templater(
 			[
 				'slug'   => $this->template,
 				'dir'    => $this->config->get_app_directory(),
-				'params' => $this->params,
+				'params' => $content_params,
 			]
 		);
 
-		$content_templater->subject = $subject;
-
 		$content = $content_templater->render( false );
 
 		// Now send the email.
@@ -163,18 +176,20 @@ public function send( $to ) {
 	 *
 	 * @return string
 	 */
-	protected function shortcodes( $content ) {
+	protected function shortcodes( string $content ): string {
 
-		// assert( ! empty( $content ) );
 
 		// Perform shortcode replacement.
 		foreach ( $this->params as $key => $value ) {
 
 			if ( is_string( $value ) ) {
 
-				$content = preg_replace(
-					'{{{(| )' . $key . '( |)}}}',
-					$value,
+				$replacement = $value; // Capture for use inside closure.
+				$content     = preg_replace_callback(
+					'{{{(| )' . preg_quote( $key, '{' ) . '( |)}}}',
+					static function () use ( $replacement ) {
+						return $replacement;
+					},
 					$content
 				);
 
diff --git a/src/View/ThemeableView.php b/src/View/ThemeableView.php
index 2eae861..529c1e0 100644
--- a/src/View/ThemeableView.php
+++ b/src/View/ThemeableView.php
@@ -35,9 +35,16 @@ class ThemeableView extends View {
 	/**
 	 * Application config object.
 	 *
-	 * @var object
+	 * @var Config
 	 */
-	protected $config;
+	protected Config $config;
+
+	/**
+	 * Template slug.
+	 *
+	 * @var string
+	 */
+	protected string $template;
 
 	/**
 	 * Constructor.
@@ -45,7 +52,7 @@ class ThemeableView extends View {
 	 * @param Config $config   Application configuration object.
 	 * @param string $template Slug of the template to use.
 	 */
-	public function __construct( Config $config, $template ) {
+	public function __construct( Config $config, string $template ) {
 
 		$this->config   = $config;
 		$this->template = $template;
@@ -55,9 +62,11 @@ public function __construct( Config $config, $template ) {
 	 * Renders the given template file.  By default, it will use the template in the theme.  If there is no template in
 	 * the theme, it will look in the 'template' directory in the application directory.
 	 *
-	 * @param boolean $output Whether to output the content or return as string (default true).
+	 * @param bool $output Whether to output the content or return as string (default true).
+	 *
+	 * @return string|false|null
 	 */
-	public function render( $output = true ) {
+	public function render( bool $output = true ): string|false|null {
 
 		// Build the template.
 		$templater = new Templater(