diff --git a/CRM/MembershipExtras/Upgrader.php b/CRM/MembershipExtras/Upgrader.php
index f2c18830..b02e993d 100755
--- a/CRM/MembershipExtras/Upgrader.php
+++ b/CRM/MembershipExtras/Upgrader.php
@@ -5,7 +5,7 @@
  * enabling and disabling the extension. Also includes the code
  * to run the upgrade steps defined in Upgrader/Steps/ directory.
  */
-class CRM_MembershipExtras_Upgrader extends CRM_MembershipExtras_Upgrader_Base {
+class CRM_MembershipExtras_Upgrader extends CRM_Extension_Upgrader_Base {
 
   public function postInstall() {
     // steps that create new entities.
@@ -78,7 +78,7 @@ public function uninstall() {
   }
 
   // To reduce the size of this Upgrader class we move upgraders to Upgrader/Steps folder.
-  // The functions below override the ones defined in CRM_MembershipExtras_Upgrader_Base file.
+  // The functions below override the ones defined in CRM_Extension_Upgrader_Base file.
   // These functions allow Civi to process the upgraders added in the Upgrader/Steps folder
   // because without these functions Civi will not process them by default.
 
@@ -100,26 +100,23 @@ public function hasPendingRevisions() {
   /**
    * @inheritdoc
    */
-  public function enqueuePendingRevisions(CRM_Queue_Queue $queue) {
+  public function enqueuePendingRevisions() {
     $currentRevisionNum = (int) $this->getCurrentRevision();
     foreach ($this->getRevisions() as $revisionClass => $revisionNum) {
       if ($revisionNum <= $currentRevisionNum) {
         continue;
       }
-      $tsParams = [1 => $this->extensionName, 2 => $revisionNum];
-      $title = ts('Upgrade %1 to revision %2', $tsParams);
+      $title = ts('Upgrade %1 to revision %2', [
+        1 => $this->extensionName,
+        2 => $revisionNum,
+      ]);
       $upgradeTask = new CRM_Queue_Task(
         [get_class($this), 'runStepUpgrade'],
         [(new $revisionClass())],
         $title
       );
-      $queue->createItem($upgradeTask);
-      $setRevisionTask = new CRM_Queue_Task(
-        [get_class($this), '_queueAdapter'],
-        ['setCurrentRevision', $revisionNum],
-        $title
-      );
-      $queue->createItem($setRevisionTask);
+      $this->queue->createItem($upgradeTask);
+      $this->appendTask($title, 'setCurrentRevision', $revisionNum);
     }
   }
 
diff --git a/CRM/MembershipExtras/Upgrader/Base.php b/CRM/MembershipExtras/Upgrader/Base.php
deleted file mode 100644
index bf4d7119..00000000
--- a/CRM/MembershipExtras/Upgrader/Base.php
+++ /dev/null
@@ -1,396 +0,0 @@
-<?php
-
-// AUTO-GENERATED FILE -- Civix may overwrite any changes made to this file
-use CRM_MembershipExtras_ExtensionUtil as E;
-
-/**
- * Base class which provides helpers to execute upgrade logic
- */
-class CRM_MembershipExtras_Upgrader_Base {
-
-  /**
-   * @var CRM_MembershipExtras_Upgrader_Base
-   */
-  public static $instance;
-
-  /**
-   * @var CRM_Queue_TaskContext
-   */
-  protected $ctx;
-
-  /**
-   * @var string
-   *   eg 'com.example.myextension'
-   */
-  protected $extensionName;
-
-  /**
-   * @var string
-   *   full path to the extension's source tree
-   */
-  protected $extensionDir;
-
-  /**
-   * @var array
-   *   sorted numerically
-   */
-  private $revisions;
-
-  /**
-   * @var bool
-   *   Flag to clean up extension revision data in civicrm_setting
-   */
-  private $revisionStorageIsDeprecated = FALSE;
-
-  /**
-   * Obtain a reference to the active upgrade handler.
-   */
-  public static function instance() {
-    if (!self::$instance) {
-      self::$instance = new CRM_MembershipExtras_Upgrader(
-        'uk.co.compucorp.membershipextras',
-        E::path()
-      );
-    }
-    return self::$instance;
-  }
-
-  /**
-   * Adapter that lets you add normal (non-static) member functions to the queue.
-   *
-   * Note: Each upgrader instance should only be associated with one
-   * task-context; otherwise, this will be non-reentrant.
-   *
-   * ```
-   * CRM_MembershipExtras_Upgrader_Base::_queueAdapter($ctx, 'methodName', 'arg1', 'arg2');
-   * ```
-   */
-  public static function _queueAdapter() {
-    $instance = self::instance();
-    $args = func_get_args();
-    $instance->ctx = array_shift($args);
-    $instance->queue = $instance->ctx->queue;
-    $method = array_shift($args);
-    return call_user_func_array([$instance, $method], $args);
-  }
-
-  /**
-   * CRM_MembershipExtras_Upgrader_Base constructor.
-   *
-   * @param $extensionName
-   * @param $extensionDir
-   */
-  public function __construct($extensionName, $extensionDir) {
-    $this->extensionName = $extensionName;
-    $this->extensionDir = $extensionDir;
-  }
-
-  // ******** Task helpers ********
-
-  /**
-   * Run a CustomData file.
-   *
-   * @param string $relativePath
-   *   the CustomData XML file path (relative to this extension's dir)
-   * @return bool
-   */
-  public function executeCustomDataFile($relativePath) {
-    $xml_file = $this->extensionDir . '/' . $relativePath;
-    return $this->executeCustomDataFileByAbsPath($xml_file);
-  }
-
-  /**
-   * Run a CustomData file
-   *
-   * @param string $xml_file
-   *   the CustomData XML file path (absolute path)
-   *
-   * @return bool
-   */
-  protected function executeCustomDataFileByAbsPath($xml_file) {
-    $import = new CRM_Utils_Migrate_Import();
-    $import->run($xml_file);
-    return TRUE;
-  }
-
-  /**
-   * Run a SQL file.
-   *
-   * @param string $relativePath
-   *   the SQL file path (relative to this extension's dir)
-   *
-   * @return bool
-   */
-  public function executeSqlFile($relativePath) {
-    CRM_Utils_File::sourceSQLFile(
-      CIVICRM_DSN,
-      $this->extensionDir . DIRECTORY_SEPARATOR . $relativePath
-    );
-    return TRUE;
-  }
-
-  /**
-   * Run the sql commands in the specified file.
-   *
-   * @param string $tplFile
-   *   The SQL file path (relative to this extension's dir).
-   *   Ex: "sql/mydata.mysql.tpl".
-   *
-   * @return bool
-   * @throws \CRM_Core_Exception
-   */
-  public function executeSqlTemplate($tplFile) {
-    // Assign multilingual variable to Smarty.
-    $upgrade = new CRM_Upgrade_Form();
-
-    $tplFile = CRM_Utils_File::isAbsolute($tplFile) ? $tplFile : $this->extensionDir . DIRECTORY_SEPARATOR . $tplFile;
-    $smarty = CRM_Core_Smarty::singleton();
-    $smarty->assign('domainID', CRM_Core_Config::domainID());
-    CRM_Utils_File::sourceSQLFile(
-      CIVICRM_DSN, $smarty->fetch($tplFile), NULL, TRUE
-    );
-    return TRUE;
-  }
-
-  /**
-   * Run one SQL query.
-   *
-   * This is just a wrapper for CRM_Core_DAO::executeSql, but it
-   * provides syntactic sugar for queueing several tasks that
-   * run different queries
-   *
-   * @return bool
-   */
-  public function executeSql($query, $params = []) {
-    // FIXME verify that we raise an exception on error
-    CRM_Core_DAO::executeQuery($query, $params);
-    return TRUE;
-  }
-
-  /**
-   * Syntactic sugar for enqueuing a task which calls a function in this class.
-   *
-   * The task is weighted so that it is processed
-   * as part of the currently-pending revision.
-   *
-   * After passing the $funcName, you can also pass parameters that will go to
-   * the function. Note that all params must be serializable.
-   */
-  public function addTask($title) {
-    $args = func_get_args();
-    $title = array_shift($args);
-    $task = new CRM_Queue_Task(
-      [get_class($this), '_queueAdapter'],
-      $args,
-      $title
-    );
-    return $this->queue->createItem($task, ['weight' => -1]);
-  }
-
-  // ******** Revision-tracking helpers ********
-
-  /**
-   * Determine if there are any pending revisions.
-   *
-   * @return bool
-   */
-  public function hasPendingRevisions() {
-    $revisions = $this->getRevisions();
-    $currentRevision = $this->getCurrentRevision();
-
-    if (empty($revisions)) {
-      return FALSE;
-    }
-    if (empty($currentRevision)) {
-      return TRUE;
-    }
-
-    return ($currentRevision < max($revisions));
-  }
-
-  /**
-   * Add any pending revisions to the queue.
-   *
-   * @param CRM_Queue_Queue $queue
-   */
-  public function enqueuePendingRevisions(CRM_Queue_Queue $queue) {
-    $this->queue = $queue;
-
-    $currentRevision = $this->getCurrentRevision();
-    foreach ($this->getRevisions() as $revision) {
-      if ($revision > $currentRevision) {
-        $title = E::ts('Upgrade %1 to revision %2', [
-          1 => $this->extensionName,
-          2 => $revision,
-        ]);
-
-        // note: don't use addTask() because it sets weight=-1
-
-        $task = new CRM_Queue_Task(
-          [get_class($this), '_queueAdapter'],
-          ['upgrade_' . $revision],
-          $title
-        );
-        $this->queue->createItem($task);
-
-        $task = new CRM_Queue_Task(
-          [get_class($this), '_queueAdapter'],
-          ['setCurrentRevision', $revision],
-          $title
-        );
-        $this->queue->createItem($task);
-      }
-    }
-  }
-
-  /**
-   * Get a list of revisions.
-   *
-   * @return array
-   *   revisionNumbers sorted numerically
-   */
-  public function getRevisions() {
-    if (!is_array($this->revisions)) {
-      $this->revisions = [];
-
-      $clazz = new ReflectionClass(get_class($this));
-      $methods = $clazz->getMethods();
-      foreach ($methods as $method) {
-        if (preg_match('/^upgrade_(.*)/', $method->name, $matches)) {
-          $this->revisions[] = $matches[1];
-        }
-      }
-      sort($this->revisions, SORT_NUMERIC);
-    }
-
-    return $this->revisions;
-  }
-
-  public function getCurrentRevision() {
-    $revision = CRM_Core_BAO_Extension::getSchemaVersion($this->extensionName);
-    if (!$revision) {
-      $revision = $this->getCurrentRevisionDeprecated();
-    }
-    return $revision;
-  }
-
-  private function getCurrentRevisionDeprecated() {
-    $key = $this->extensionName . ':version';
-    if ($revision = \Civi::settings()->get($key)) {
-      $this->revisionStorageIsDeprecated = TRUE;
-    }
-    return $revision;
-  }
-
-  public function setCurrentRevision($revision) {
-    CRM_Core_BAO_Extension::setSchemaVersion($this->extensionName, $revision);
-    // clean up legacy schema version store (CRM-19252)
-    $this->deleteDeprecatedRevision();
-    return TRUE;
-  }
-
-  private function deleteDeprecatedRevision() {
-    if ($this->revisionStorageIsDeprecated) {
-      $setting = new CRM_Core_BAO_Setting();
-      $setting->name = $this->extensionName . ':version';
-      $setting->delete();
-      CRM_Core_Error::debug_log_message("Migrated extension schema revision ID for {$this->extensionName} from civicrm_setting (deprecated) to civicrm_extension.\n");
-    }
-  }
-
-  // ******** Hook delegates ********
-
-  /**
-   * @see https://docs.civicrm.org/dev/en/latest/hooks/hook_civicrm_install
-   */
-  public function onInstall() {
-    $files = glob($this->extensionDir . '/sql/*_install.sql');
-    if (is_array($files)) {
-      foreach ($files as $file) {
-        CRM_Utils_File::sourceSQLFile(CIVICRM_DSN, $file);
-      }
-    }
-    $files = glob($this->extensionDir . '/sql/*_install.mysql.tpl');
-    if (is_array($files)) {
-      foreach ($files as $file) {
-        $this->executeSqlTemplate($file);
-      }
-    }
-    $files = glob($this->extensionDir . '/xml/*_install.xml');
-    if (is_array($files)) {
-      foreach ($files as $file) {
-        $this->executeCustomDataFileByAbsPath($file);
-      }
-    }
-    if (is_callable([$this, 'install'])) {
-      $this->install();
-    }
-  }
-
-  /**
-   * @see https://docs.civicrm.org/dev/en/latest/hooks/hook_civicrm_postInstall
-   */
-  public function onPostInstall() {
-    $revisions = $this->getRevisions();
-    if (!empty($revisions)) {
-      $this->setCurrentRevision(max($revisions));
-    }
-    if (is_callable([$this, 'postInstall'])) {
-      $this->postInstall();
-    }
-  }
-
-  /**
-   * @see https://docs.civicrm.org/dev/en/latest/hooks/hook_civicrm_uninstall
-   */
-  public function onUninstall() {
-    $files = glob($this->extensionDir . '/sql/*_uninstall.mysql.tpl');
-    if (is_array($files)) {
-      foreach ($files as $file) {
-        $this->executeSqlTemplate($file);
-      }
-    }
-    if (is_callable([$this, 'uninstall'])) {
-      $this->uninstall();
-    }
-    $files = glob($this->extensionDir . '/sql/*_uninstall.sql');
-    if (is_array($files)) {
-      foreach ($files as $file) {
-        CRM_Utils_File::sourceSQLFile(CIVICRM_DSN, $file);
-      }
-    }
-  }
-
-  /**
-   * @see https://docs.civicrm.org/dev/en/latest/hooks/hook_civicrm_enable
-   */
-  public function onEnable() {
-    // stub for possible future use
-    if (is_callable([$this, 'enable'])) {
-      $this->enable();
-    }
-  }
-
-  /**
-   * @see https://docs.civicrm.org/dev/en/latest/hooks/hook_civicrm_disable
-   */
-  public function onDisable() {
-    // stub for possible future use
-    if (is_callable([$this, 'disable'])) {
-      $this->disable();
-    }
-  }
-
-  public function onUpgrade($op, CRM_Queue_Queue $queue = NULL) {
-    switch ($op) {
-      case 'check':
-        return [$this->hasPendingRevisions()];
-
-      case 'enqueue':
-        return $this->enqueuePendingRevisions($queue);
-
-      default:
-    }
-  }
-
-}
diff --git a/info.xml b/info.xml
index d5f066ad..43aa0998 100755
--- a/info.xml
+++ b/info.xml
@@ -20,10 +20,11 @@
   </comments>
   <civix>
     <namespace>CRM/MembershipExtras</namespace>
-    <format>22.05.2</format>
+    <format>23.02.1</format>
   </civix>
   <classloader>
     <psr4 prefix="Civi\" path="Civi"/>
+    <psr0 prefix="CRM_" path="."/>
   </classloader>
   <urls>
     <url desc="Documentation">https://github.com/compucorp/uk.co.compucorp.membershipextras/blob/master/readme.md</url>
@@ -31,5 +32,8 @@
   <mixins>
     <mixin>menu-xml@1.0.0</mixin>
     <mixin>setting-php@1.0.0</mixin>
+    <mixin>smarty-v2@1.0.1</mixin>
+    <mixin>entity-types-php@1.0.0</mixin>
   </mixins>
+  <upgrader>CRM_MembershipExtras_Upgrader</upgrader>
 </extension>
diff --git a/js/paymentPlanToggler.js b/js/paymentPlanToggler.js
index 2360b965..f30daa90 100644
--- a/js/paymentPlanToggler.js
+++ b/js/paymentPlanToggler.js
@@ -62,7 +62,7 @@ function paymentPlanToggler(togglerValue, currencySymbol) {
     function hideOfflineAutorenewField() {
       const autoRenewSelector = '.custom-group-offline_autorenew_option';
 
-      waitForElement($, '#customData',
+      waitForElement($, '#customData_Membership',
         element => isPaymentPlanTabActive()
           ? $(autoRenewSelector).show()
           : $(autoRenewSelector).hide()
@@ -437,7 +437,7 @@ function paymentPlanToggler(togglerValue, currencySymbol) {
 
     /**
      * Prevent the payment tab link from appending hash to the URL
-     * 
+     *
      * This resolves the issue with the activity tab not opening after signing up for a membership.
      */
     function preventPaymentTabLinkAction() {
diff --git a/membershipextras.civix.php b/membershipextras.civix.php
index 4367ac71..1cbc43a8 100644
--- a/membershipextras.civix.php
+++ b/membershipextras.civix.php
@@ -24,7 +24,7 @@ class CRM_MembershipExtras_ExtensionUtil {
    *   Translated text.
    * @see ts
    */
-  public static function ts($text, $params = []) {
+  public static function ts($text, $params = []): string {
     if (!array_key_exists('domain', $params)) {
       $params['domain'] = [self::LONG_NAME, NULL];
     }
@@ -41,7 +41,7 @@ public static function ts($text, $params = []) {
    *   Ex: 'http://example.org/sites/default/ext/org.example.foo'.
    *   Ex: 'http://example.org/sites/default/ext/org.example.foo/css/foo.css'.
    */
-  public static function url($file = NULL) {
+  public static function url($file = NULL): string {
     if ($file === NULL) {
       return rtrim(CRM_Core_Resources::singleton()->getUrl(self::LONG_NAME), '/');
     }
@@ -84,27 +84,17 @@ public static function findClass($suffix) {
  *
  * @link https://docs.civicrm.org/dev/en/latest/hooks/hook_civicrm_config
  */
-function _membershipextras_civix_civicrm_config(&$config = NULL) {
+function _membershipextras_civix_civicrm_config($config = NULL) {
   static $configured = FALSE;
   if ($configured) {
     return;
   }
   $configured = TRUE;
 
-  $template = CRM_Core_Smarty::singleton();
-
   $extRoot = __DIR__ . DIRECTORY_SEPARATOR;
-  $extDir = $extRoot . 'templates';
-
-  if (is_array($template->template_dir)) {
-    array_unshift($template->template_dir, $extDir);
-  }
-  else {
-    $template->template_dir = [$extDir, $template->template_dir];
-  }
-
   $include_path = $extRoot . PATH_SEPARATOR . get_include_path();
   set_include_path($include_path);
+  // Based on <compatibility>, this does not currently require mixin/polyfill.php.
 }
 
 /**
@@ -114,35 +104,7 @@ function _membershipextras_civix_civicrm_config(&$config = NULL) {
  */
 function _membershipextras_civix_civicrm_install() {
   _membershipextras_civix_civicrm_config();
-  if ($upgrader = _membershipextras_civix_upgrader()) {
-    $upgrader->onInstall();
-  }
-}
-
-/**
- * Implements hook_civicrm_postInstall().
- *
- * @link https://docs.civicrm.org/dev/en/latest/hooks/hook_civicrm_postInstall
- */
-function _membershipextras_civix_civicrm_postInstall() {
-  _membershipextras_civix_civicrm_config();
-  if ($upgrader = _membershipextras_civix_upgrader()) {
-    if (is_callable([$upgrader, 'onPostInstall'])) {
-      $upgrader->onPostInstall();
-    }
-  }
-}
-
-/**
- * Implements hook_civicrm_uninstall().
- *
- * @link https://docs.civicrm.org/dev/en/latest/hooks/hook_civicrm_uninstall
- */
-function _membershipextras_civix_civicrm_uninstall() {
-  _membershipextras_civix_civicrm_config();
-  if ($upgrader = _membershipextras_civix_upgrader()) {
-    $upgrader->onUninstall();
-  }
+  // Based on <compatibility>, this does not currently require mixin/polyfill.php.
 }
 
 /**
@@ -150,58 +112,9 @@ function _membershipextras_civix_civicrm_uninstall() {
  *
  * @link https://docs.civicrm.org/dev/en/latest/hooks/hook_civicrm_enable
  */
-function _membershipextras_civix_civicrm_enable() {
+function _membershipextras_civix_civicrm_enable(): void {
   _membershipextras_civix_civicrm_config();
-  if ($upgrader = _membershipextras_civix_upgrader()) {
-    if (is_callable([$upgrader, 'onEnable'])) {
-      $upgrader->onEnable();
-    }
-  }
-}
-
-/**
- * (Delegated) Implements hook_civicrm_disable().
- *
- * @link https://docs.civicrm.org/dev/en/latest/hooks/hook_civicrm_disable
- * @return mixed
- */
-function _membershipextras_civix_civicrm_disable() {
-  _membershipextras_civix_civicrm_config();
-  if ($upgrader = _membershipextras_civix_upgrader()) {
-    if (is_callable([$upgrader, 'onDisable'])) {
-      $upgrader->onDisable();
-    }
-  }
-}
-
-/**
- * (Delegated) Implements hook_civicrm_upgrade().
- *
- * @param $op string, the type of operation being performed; 'check' or 'enqueue'
- * @param $queue CRM_Queue_Queue, (for 'enqueue') the modifiable list of pending up upgrade tasks
- *
- * @return mixed
- *   based on op. for 'check', returns array(boolean) (TRUE if upgrades are pending)
- *   for 'enqueue', returns void
- *
- * @link https://docs.civicrm.org/dev/en/latest/hooks/hook_civicrm_upgrade
- */
-function _membershipextras_civix_civicrm_upgrade($op, CRM_Queue_Queue $queue = NULL) {
-  if ($upgrader = _membershipextras_civix_upgrader()) {
-    return $upgrader->onUpgrade($op, $queue);
-  }
-}
-
-/**
- * @return CRM_MembershipExtras_Upgrader
- */
-function _membershipextras_civix_upgrader() {
-  if (!file_exists(__DIR__ . '/CRM/MembershipExtras/Upgrader.php')) {
-    return NULL;
-  }
-  else {
-    return CRM_MembershipExtras_Upgrader_Base::instance();
-  }
+  // Based on <compatibility>, this does not currently require mixin/polyfill.php.
 }
 
 /**
@@ -220,8 +133,8 @@ function _membershipextras_civix_insert_navigation_menu(&$menu, $path, $item) {
   if (empty($path)) {
     $menu[] = [
       'attributes' => array_merge([
-        'label'      => CRM_Utils_Array::value('name', $item),
-        'active'     => 1,
+        'label' => $item['name'] ?? NULL,
+        'active' => 1,
       ], $item),
     ];
     return TRUE;
@@ -285,30 +198,3 @@ function _membershipextras_civix_fixNavigationMenuItems(&$nodes, &$maxNavID, $pa
     }
   }
 }
-
-/**
- * (Delegated) Implements hook_civicrm_entityTypes().
- *
- * Find any *.entityType.php files, merge their content, and return.
- *
- * @link https://docs.civicrm.org/dev/en/latest/hooks/hook_civicrm_entityTypes
- */
-function _membershipextras_civix_civicrm_entityTypes(&$entityTypes) {
-  $entityTypes = array_merge($entityTypes, [
-    'CRM_MembershipExtras_DAO_AutoMembershipUpgradeRule' => [
-      'name' => 'AutoMembershipUpgradeRule',
-      'class' => 'CRM_MembershipExtras_DAO_AutoMembershipUpgradeRule',
-      'table' => 'membershipextras_auto_membership_upgrade_rule',
-    ],
-    'CRM_MembershipExtras_DAO_ContributionRecurLineItem' => [
-      'name' => 'ContributionRecurLineItem',
-      'class' => 'CRM_MembershipExtras_DAO_ContributionRecurLineItem',
-      'table' => 'membershipextras_subscription_line',
-    ],
-    'CRM_MembershipExtras_DAO_PaymentScheme' => [
-      'name' => 'PaymentScheme',
-      'class' => 'CRM_MembershipExtras_DAO_PaymentScheme',
-      'table' => 'civicrm_payment_scheme',
-    ],
-  ]);
-}
diff --git a/membershipextras.php b/membershipextras.php
index 66db06ea..632f23ff 100755
--- a/membershipextras.php
+++ b/membershipextras.php
@@ -24,24 +24,6 @@ function membershipextras_civicrm_install() {
   _membershipextras_civix_civicrm_install();
 }
 
-/**
- * Implements hook_civicrm_postInstall().
- *
- * @link http://wiki.civicrm.org/confluence/display/CRMDOC/hook_civicrm_postInstall
- */
-function membershipextras_civicrm_postInstall() {
-  _membershipextras_civix_civicrm_postInstall();
-}
-
-/**
- * Implements hook_civicrm_uninstall().
- *
- * @link http://wiki.civicrm.org/confluence/display/CRMDOC/hook_civicrm_uninstall
- */
-function membershipextras_civicrm_uninstall() {
-  _membershipextras_civix_civicrm_uninstall();
-}
-
 /**
  * Implements hook_civicrm_enable().
  *
@@ -51,24 +33,6 @@ function membershipextras_civicrm_enable() {
   _membershipextras_civix_civicrm_enable();
 }
 
-/**
- * Implements hook_civicrm_disable().
- *
- * @link http://wiki.civicrm.org/confluence/display/CRMDOC/hook_civicrm_disable
- */
-function membershipextras_civicrm_disable() {
-  _membershipextras_civix_civicrm_disable();
-}
-
-/**
- * Implements hook_civicrm_upgrade().
- *
- * @link http://wiki.civicrm.org/confluence/display/CRMDOC/hook_civicrm_upgrade
- */
-function membershipextras_civicrm_upgrade($op, CRM_Queue_Queue $queue = NULL) {
-  return _membershipextras_civix_civicrm_upgrade($op, $queue);
-}
-
 /**
  * Implements hook_civicrm_navigationMenu().
  *
@@ -416,13 +380,6 @@ function membershipextras_civicrm_alterContent(&$content, $context, $tplName, &$
   }
 }
 
-/**
- * Implements hook_civicrm_entityTypes().
- */
-function membershipextras_civicrm_entityTypes(&$entityTypes) {
-  return _membershipextras_civix_civicrm_entityTypes($entityTypes);
-}
-
 function membershipextras_civicrm_preProcess($formName, $form) {
   if ($formName === 'CRM_Contribute_Form_ContributionView') {
     $preProcessor = new CRM_MembershipExtras_Hook_PreProcess_ContributionView($form);
diff --git a/mixin/entity-types-php@1.0.0.mixin.php b/mixin/entity-types-php@1.0.0.mixin.php
new file mode 100644
index 00000000..8ec4203d
--- /dev/null
+++ b/mixin/entity-types-php@1.0.0.mixin.php
@@ -0,0 +1,36 @@
+<?php
+
+/**
+ * Auto-register entity declarations from `xml/schema/...*.entityType.php`.
+ *
+ * @mixinName entity-types-php
+ * @mixinVersion 1.0.0
+ * @since 5.57
+ *
+ * @param CRM_Extension_MixInfo $mixInfo
+ *   On newer deployments, this will be an instance of MixInfo. On older deployments, Civix may polyfill with a work-a-like.
+ * @param \CRM_Extension_BootCache $bootCache
+ *   On newer deployments, this will be an instance of MixInfo. On older deployments, Civix may polyfill with a work-a-like.
+ */
+return function ($mixInfo, $bootCache) {
+
+  /**
+   * @param \Civi\Core\Event\GenericHookEvent $e
+   * @see CRM_Utils_Hook::entityTypes()
+   */
+  Civi::dispatcher()->addListener('hook_civicrm_entityTypes', function ($e) use ($mixInfo) {
+    // When deactivating on a polyfill/pre-mixin system, listeners may not cleanup automatically.
+    if (!$mixInfo->isActive() || !is_dir($mixInfo->getPath('xml/schema/CRM'))) {
+      return;
+    }
+
+    $files = (array) glob($mixInfo->getPath('xml/schema/CRM/*/*.entityType.php'));
+    foreach ($files as $file) {
+      $entities = include $file;
+      foreach ($entities as $entity) {
+        $e->entityTypes[$entity['class']] = $entity;
+      }
+    }
+  });
+
+};
diff --git a/mixin/smarty-v2@1.0.1.mixin.php b/mixin/smarty-v2@1.0.1.mixin.php
new file mode 100644
index 00000000..5972dbdc
--- /dev/null
+++ b/mixin/smarty-v2@1.0.1.mixin.php
@@ -0,0 +1,51 @@
+<?php
+
+/**
+ * Auto-register "templates/" folder.
+ *
+ * @mixinName smarty-v2
+ * @mixinVersion 1.0.1
+ * @since 5.59
+ *
+ * @param CRM_Extension_MixInfo $mixInfo
+ *   On newer deployments, this will be an instance of MixInfo. On older deployments, Civix may polyfill with a work-a-like.
+ * @param \CRM_Extension_BootCache $bootCache
+ *   On newer deployments, this will be an instance of MixInfo. On older deployments, Civix may polyfill with a work-a-like.
+ */
+return function ($mixInfo, $bootCache) {
+  $dir = $mixInfo->getPath('templates');
+  if (!file_exists($dir)) {
+    return;
+  }
+
+  $register = function() use ($dir) {
+    // This implementation has a theoretical edge-case bug on older versions of CiviCRM where a template could
+    // be registered more than once.
+    CRM_Core_Smarty::singleton()->addTemplateDir($dir);
+  };
+
+  // Let's figure out what environment we're in -- so that we know the best way to call $register().
+
+  if (!empty($GLOBALS['_CIVIX_MIXIN_POLYFILL'])) {
+    // Polyfill Loader (v<=5.45): We're already in the middle of firing `hook_config`.
+    if ($mixInfo->isActive()) {
+      $register();
+    }
+    return;
+  }
+
+  if (CRM_Extension_System::singleton()->getManager()->extensionIsBeingInstalledOrEnabled($mixInfo->longName)) {
+    // New Install, Standard Loader: The extension has just been enabled, and we're now setting it up.
+    // System has already booted. New templates may be needed for upcoming installation steps.
+    $register();
+    return;
+  }
+
+  // Typical Pageview, Standard Loader: Defer the actual registration for a moment -- to ensure that Smarty is online.
+  \Civi::dispatcher()->addListener('hook_civicrm_config', function() use ($mixInfo, $register) {
+    if ($mixInfo->isActive()) {
+      $register();
+    }
+  });
+
+};