diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 80a0f827..3a617ab0 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -6,6 +6,7 @@ Changelog
 - Fix #512: Validate `from` pagination cursor to prevent unbounded conversation loading
 - Fix #514: Optimize pin icon rendering on the inbox message list
 - Fix #515: Reduce database queries in the inbox list, conversation loading, reply action and unread count polling
+- Enh: Automated code refactoring for HumHub 1.18.1 using Rector
 
 3.3.12 (July 16, 2026)
 ----------------------
diff --git a/models/Message.php b/models/Message.php
index 482e1194..0734c848 100644
--- a/models/Message.php
+++ b/models/Message.php
@@ -189,9 +189,7 @@ public function getUsersCount(): int
             return count($this->users);
         }
 
-        if ($this->_userCount === null) {
-            $this->_userCount = $this->getUsers()->count();
-        }
+        $this->_userCount ??= $this->getUsers()->count();
 
         return $this->_userCount;
     }
@@ -283,13 +281,11 @@ public function getLastEntry(): ?MessageEntry
             return $this->lastEntryRelation;
         }
 
-        if ($this->_lastEntry === null) {
-            $this->_lastEntry = MessageEntry::find()
-                ->where(['message_id' => $this->id])
-                ->orderBy('created_at DESC')
-                ->limit(1)
-                ->one();
-        }
+        $this->_lastEntry ??= MessageEntry::find()
+            ->where(['message_id' => $this->id])
+            ->orderBy('created_at DESC')
+            ->limit(1)
+            ->one();
 
         return $this->_lastEntry;
     }
diff --git a/models/UserMessage.php b/models/UserMessage.php
index 61db924f..c859b815 100644
--- a/models/UserMessage.php
+++ b/models/UserMessage.php
@@ -135,9 +135,7 @@ public static function invalidateNewMessageCountCache($userId): void
 
     public static function findByUser($userId = null)
     {
-        if ($userId === null) {
-            $userId = Yii::$app->user->id;
-        }
+        $userId ??= Yii::$app->user->id;
 
         if ($userId instanceof User) {
             $userId = $userId->id;
diff --git a/search/SearchProvider.php b/search/SearchProvider.php
index 5e5024ed..ac94620d 100644
--- a/search/SearchProvider.php
+++ b/search/SearchProvider.php
@@ -90,9 +90,7 @@ public function getResults(int $maxResults): array
      */
     public function getService(): MetaSearchService
     {
-        if ($this->service === null) {
-            $this->service = new MetaSearchService($this);
-        }
+        $this->service ??= new MetaSearchService($this);
 
         return $this->service;
     }
diff --git a/widgets/InboxMessagePreview.php b/widgets/InboxMessagePreview.php
index 7e05ed34..03d6be18 100644
--- a/widgets/InboxMessagePreview.php
+++ b/widgets/InboxMessagePreview.php
@@ -53,9 +53,7 @@ private function getOptions(): array
 
     public function getMessage(): Message
     {
-        if ($this->_message === null) {
-            $this->_message = $this->userMessage->message;
-        }
+        $this->_message ??= $this->userMessage->message;
 
         return $this->_message;
     }