diff --git a/phpstan.neon b/phpstan.neon
index 64e5e97c..93f52b64 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,5 +1,5 @@
 parameters:
-    level: 2
+    level: 3
     paths:
         - src/
         - tests/
diff --git a/psalm.xml b/psalm.xml
index 5df66af5..a3b7bdbb 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0"?>
 <psalm
-        errorLevel="7"
+        errorLevel="6"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns="https://getpsalm.org/schema/config"
         xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
diff --git a/src/Domain/Envelope.php b/src/Domain/Envelope.php
index 382b79cb..abf3243f 100644
--- a/src/Domain/Envelope.php
+++ b/src/Domain/Envelope.php
@@ -16,6 +16,8 @@
 use Streak\Domain\Id\UUID;
 
 /**
+ * @template T of object
+ *
  * @author Alan Gabriel Bem <alan.bem@gmail.com>
  */
 interface Envelope extends ValueObject
@@ -24,6 +26,9 @@ public function uuid(): UUID;
 
     public function name(): string;
 
+    /**
+     * @return T
+     */
     public function message();
 
     /**
@@ -33,5 +38,8 @@ public function message();
      */
     public function get($name);
 
+    /**
+     * @return array<scalar, scalar>
+     */
     public function metadata(): array;
 }
diff --git a/src/Domain/Event/Envelope.php b/src/Domain/Event/Envelope.php
index 47ac1484..c81b6a04 100644
--- a/src/Domain/Event/Envelope.php
+++ b/src/Domain/Event/Envelope.php
@@ -21,6 +21,7 @@
  * @author Alan Gabriel Bem <alan.bem@gmail.com>
  *
  * @template T of Event
+ * @implements Domain\Envelope<T>
  *
  * @see \Streak\Domain\Event\EnvelopeTest
  */
@@ -51,9 +52,6 @@ public function __construct(UUID $uuid, string $name, private Event $message, Do
         }
     }
 
-    /**
-     * @return Envelope<T>
-     */
     public static function new(Event $message, Domain\Id $producerId, ?int $version = null): self
     {
         return new self(UUID::random(), $message::class, $message, $producerId, $producerId, $version);
@@ -69,10 +67,7 @@ public function name(): string
         return $this->get(self::METADATA_NAME);
     }
 
-    /**
-     * @return T
-     */
-    public function message(): Event
+    public function message()
     {
         return $this->message;
     }
diff --git a/src/Domain/Event/Listener/Factory.php b/src/Domain/Event/Listener/Factory.php
index 1ca6760d..6a42573d 100644
--- a/src/Domain/Event/Listener/Factory.php
+++ b/src/Domain/Event/Listener/Factory.php
@@ -15,20 +15,25 @@
 
 use Streak\Domain\Event;
 use Streak\Domain\Event\Exception\InvalidEventGiven;
-use Streak\Domain\Event\Listener;
 use Streak\Domain\Exception\InvalidIdGiven;
 
 /**
+ * @template T of Event\Listener
+ *
  * @author Alan Gabriel Bem <alan.bem@gmail.com>
  */
 interface Factory
 {
     /**
+     * @return T
+     *
      * @throws InvalidIdGiven
      */
-    public function create(Listener\Id $id): Listener;
+    public function create(Event\Listener\Id $id): Event\Listener;
 
     /**
+     * @return T
+     *
      * @throws InvalidEventGiven
      */
     public function createFor(Event\Envelope $event): Event\Listener;
diff --git a/src/Domain/Event/Subscription/Factory.php b/src/Domain/Event/Subscription/Factory.php
index b5ddf677..40d3a030 100644
--- a/src/Domain/Event/Subscription/Factory.php
+++ b/src/Domain/Event/Subscription/Factory.php
@@ -16,9 +16,14 @@
 use Streak\Domain\Event;
 
 /**
+ * @template T of Event\Subscription
+ *
  * @author Alan Gabriel Bem <alan.bem@gmail.com>
  */
 interface Factory
 {
+    /**
+     * @return T
+     */
     public function create(Event\Listener $listener): Event\Subscription;
 }
diff --git a/src/Infrastructure/Domain/Event/LoggingListener/Factory.php b/src/Infrastructure/Domain/Event/LoggingListener/Factory.php
index 761a368d..798e628c 100644
--- a/src/Infrastructure/Domain/Event/LoggingListener/Factory.php
+++ b/src/Infrastructure/Domain/Event/LoggingListener/Factory.php
@@ -18,6 +18,8 @@
 use Streak\Infrastructure\Domain\Event\LoggingListener;
 
 /**
+ * @implements Event\Listener\Factory<LoggingListener>
+ *
  * @author Alan Gabriel Bem <alan.bem@gmail.com>
  *
  * @see \Streak\Infrastructure\Domain\Event\LoggingListener\FactoryTest
@@ -28,14 +30,14 @@ public function __construct(private Event\Listener\Factory $factory, private Log
     {
     }
 
-    public function create(Event\Listener\Id $id): Event\Listener
+    public function create(Event\Listener\Id $id): LoggingListener
     {
         $saga = $this->factory->create($id);
 
         return new LoggingListener($saga, $this->logger);
     }
 
-    public function createFor(Event\Envelope $event): Event\Listener
+    public function createFor(Event\Envelope $event): LoggingListener
     {
         $listener = $this->factory->createFor($event);
 
diff --git a/src/Infrastructure/Domain/Event/Sourced/Subscription/InMemoryState.php b/src/Infrastructure/Domain/Event/Sourced/Subscription/InMemoryState.php
index 3364262a..368a28b3 100644
--- a/src/Infrastructure/Domain/Event/Sourced/Subscription/InMemoryState.php
+++ b/src/Infrastructure/Domain/Event/Sourced/Subscription/InMemoryState.php
@@ -55,7 +55,7 @@ public function get(string $name)
         return $this->state[$name];
     }
 
-    public function set(string $name, $value): State
+    public function set(string $name, $value): self
     {
         $this->validate($name, $value);
 
diff --git a/src/Infrastructure/Domain/Event/Subscription/CommittingSubscription/Factory.php b/src/Infrastructure/Domain/Event/Subscription/CommittingSubscription/Factory.php
index b46bfc3f..3eb9460c 100644
--- a/src/Infrastructure/Domain/Event/Subscription/CommittingSubscription/Factory.php
+++ b/src/Infrastructure/Domain/Event/Subscription/CommittingSubscription/Factory.php
@@ -19,6 +19,8 @@
 use Streak\Infrastructure\Domain\UnitOfWork;
 
 /**
+ * @implements Event\Subscription\Factory<CommittingSubscription>
+ *
  * @author Alan Gabriel Bem <alan.bem@gmail.com>
  *
  * @see \Streak\Infrastructure\Domain\Event\Subscription\CommittingSubscription\FactoryTest
@@ -29,7 +31,7 @@ public function __construct(private Subscription\Factory $factory, private UnitO
     {
     }
 
-    public function create(Event\Listener $listener): Event\Subscription
+    public function create(Event\Listener $listener): CommittingSubscription
     {
         $subscription = $this->factory->create($listener);
 
diff --git a/src/Infrastructure/Domain/Event/Subscription/DAO.php b/src/Infrastructure/Domain/Event/Subscription/DAO.php
index 8087dcc0..a7a78fba 100644
--- a/src/Infrastructure/Domain/Event/Subscription/DAO.php
+++ b/src/Infrastructure/Domain/Event/Subscription/DAO.php
@@ -30,7 +30,7 @@ public function exists(Listener\Id $id): bool;
     /**
      * @param string[] $types
      *
-     * @return DAO\Subscription[]
+     * @return Subscription[]
      */
     public function all(array $types = [], ?bool $completed = null): iterable;
 }
diff --git a/src/Infrastructure/Domain/Event/Subscription/DAO/DbalPostgresDAO.php b/src/Infrastructure/Domain/Event/Subscription/DAO/DbalPostgresDAO.php
index 409ebb42..a2325804 100644
--- a/src/Infrastructure/Domain/Event/Subscription/DAO/DbalPostgresDAO.php
+++ b/src/Infrastructure/Domain/Event/Subscription/DAO/DbalPostgresDAO.php
@@ -30,8 +30,13 @@
  */
 class DbalPostgresDAO implements DAO
 {
-    public function __construct(private Subscription\Factory $subscriptions, private Event\Listener\Factory $listeners, private Connection $connection, private Event\Converter $converter)
-    {
+    public function __construct(
+        /** @var Subscription\Factory<DAO\Subscription> */
+        private Subscription\Factory $subscriptions,
+        private Event\Listener\Factory $listeners,
+        private Connection $connection,
+        private Event\Converter $converter
+    ) {
     }
 
     /**
@@ -69,11 +74,7 @@ public function exists(Listener\Id $id): bool
     }
 
     /**
-     * @param string[] $types
-     *
      * @throws \Doctrine\DBAL\DBALException
-     *
-     * @return Subscription[]
      */
     public function all(array $types = [], ?bool $completed = null): iterable
     {
@@ -186,7 +187,7 @@ public function drop(): void
         $statement->execute();
     }
 
-    private function fromRow($row): Subscription
+    private function fromRow($row): DAO\Subscription
     {
         $id = $row['subscription_type'];
         $id = $id::fromString($row['subscription_id']);
@@ -306,11 +307,9 @@ private function doSave(DAO\Subscription $subscription): void
     }
 
     /**
-     *
      * @throws \Doctrine\DBAL\DBALException
-     * @return \Streak\Infrastructure\Domain\Event\Subscription\DAO\Subscription|null
      */
-    private function doOne(Event\Listener\Id $id)
+    private function doOne(Event\Listener\Id $id): ?DAO\Subscription
     {
         $sql = 'SELECT subscription_type, subscription_id, subscription_version, state, started_by, started_at, last_processed_event, last_event_processed_at, completed, paused_at FROM subscriptions WHERE subscription_type = :subscription_type AND subscription_id = :subscription_id LIMIT 1';
 
diff --git a/src/Infrastructure/Domain/Event/Subscription/DAO/InMemoryDAO.php b/src/Infrastructure/Domain/Event/Subscription/DAO/InMemoryDAO.php
index 56360950..cac5f52f 100644
--- a/src/Infrastructure/Domain/Event/Subscription/DAO/InMemoryDAO.php
+++ b/src/Infrastructure/Domain/Event/Subscription/DAO/InMemoryDAO.php
@@ -60,7 +60,7 @@ public function exists(Listener\Id $id): bool
 
     public function all(array $types = [], ?bool $completed = null): iterable
     {
-        foreach ($this->subscriptions as $key => $stored) {
+        foreach ($this->subscriptions as $stored) {
             if (\count($types)) {
                 $type = $stored->id()::class;
                 if (false === \in_array($type, $types)) {
diff --git a/src/Infrastructure/Domain/Event/Subscription/DAO/Subscription.php b/src/Infrastructure/Domain/Event/Subscription/DAO/Subscription.php
index 3c09522f..29b2e418 100644
--- a/src/Infrastructure/Domain/Event/Subscription/DAO/Subscription.php
+++ b/src/Infrastructure/Domain/Event/Subscription/DAO/Subscription.php
@@ -16,6 +16,7 @@
 use Streak\Domain\Clock;
 use Streak\Domain\Event;
 use Streak\Domain\Event\Listener;
+use Streak\Domain\Event\Listener\State;
 use Streak\Domain\Event\Subscription\Exception;
 use Streak\Domain\EventStore;
 use Streak\Infrastructure\Domain\Event\Sourced\Subscription\InMemoryState;
@@ -28,12 +29,12 @@
 class Subscription implements Event\Subscription
 {
     private const LIMIT_TO_INITIAL_STREAM = 0;
-    private InMemoryState $state;
+    private State $state;
     private ?Event\Envelope $startedBy = null;
-    private ?\DateTimeImmutable $startedAt = null;
+    private ?\DateTimeImmutable $startedAt = null; // @TODO: check if needed
     private ?\DateTimeImmutable $pausedAt = null;
     private ?Event\Envelope $lastProcessedEvent = null;
-    private ?\DateTimeImmutable $lastEventProcessedAt = null;
+    private ?\DateTimeImmutable $lastEventProcessedAt = null; // @TODO: check if needed
     private int $version = 0;
     private bool $completed = false;
 
diff --git a/src/Infrastructure/Domain/Event/Subscription/DAO/Subscription/Factory.php b/src/Infrastructure/Domain/Event/Subscription/DAO/Subscription/Factory.php
index 3568288c..ccfc119e 100644
--- a/src/Infrastructure/Domain/Event/Subscription/DAO/Subscription/Factory.php
+++ b/src/Infrastructure/Domain/Event/Subscription/DAO/Subscription/Factory.php
@@ -15,9 +15,11 @@
 
 use Streak\Domain\Clock;
 use Streak\Domain\Event;
-use Streak\Infrastructure\Domain\Event\Subscription\DAO\Subscription;
+use Streak\Infrastructure\Domain\Event\Subscription\DAO;
 
 /**
+ * @implements Event\Subscription\Factory<DAO\Subscription>
+ *
  * @author Alan Gabriel Bem <alan.bem@gmail.com>
  *
  * @see \Streak\Infrastructure\Domain\Event\Subscription\DAO\Subscription\FactoryTest
@@ -28,8 +30,8 @@ public function __construct(private Clock $clock)
     {
     }
 
-    public function create(Event\Listener $listener): Event\Subscription
+    public function create(Event\Listener $listener): DAO\Subscription
     {
-        return new Subscription($listener, $this->clock);
+        return new DAO\Subscription($listener, $this->clock);
     }
 }
diff --git a/src/Infrastructure/Domain/Event/Subscription/DbalTransactionalSubscription/Factory.php b/src/Infrastructure/Domain/Event/Subscription/DbalTransactionalSubscription/Factory.php
index 86c89620..0fc0e64c 100644
--- a/src/Infrastructure/Domain/Event/Subscription/DbalTransactionalSubscription/Factory.php
+++ b/src/Infrastructure/Domain/Event/Subscription/DbalTransactionalSubscription/Factory.php
@@ -18,6 +18,8 @@
 use Streak\Infrastructure\Domain\Event\Subscription\DbalTransactionalSubscription;
 
 /**
+ * @implements Event\Subscription\Factory<DbalTransactionalSubscription>
+ *
  * @author Alan Gabriel Bem <alan.bem@gmail.com>
  *
  * @see \Streak\Infrastructure\Domain\Event\Subscription\DbalTransactionalSubscription\FactoryTest
@@ -35,7 +37,7 @@ public function __construct(private Event\Subscription\Factory $factory, private
         $this->maxTransactionSize = $maxTransactionSize;
     }
 
-    public function create(Event\Listener $listener): Event\Subscription
+    public function create(Event\Listener $listener): DbalTransactionalSubscription
     {
         $subscription = $this->factory->create($listener);
 
diff --git a/src/Infrastructure/Domain/UnitOfWork/SubscriptionDAOUnitOfWork.php b/src/Infrastructure/Domain/UnitOfWork/SubscriptionDAOUnitOfWork.php
index 186cfd3a..69f2b0ae 100644
--- a/src/Infrastructure/Domain/UnitOfWork/SubscriptionDAOUnitOfWork.php
+++ b/src/Infrastructure/Domain/UnitOfWork/SubscriptionDAOUnitOfWork.php
@@ -27,7 +27,7 @@
 class SubscriptionDAOUnitOfWork implements UnitOfWork
 {
     /**
-     * @var Subscription[]
+     * @var DAO\Subscription[]
      */
     private array $uncommited = [];
 
@@ -98,7 +98,7 @@ public function commit(): \Generator
 
             try {
                 while ($object = array_shift($this->uncommited)) {
-                    /** @var Subscription $object */
+                    /** @var DAO\Subscription $object */
                     try {
                         $this->dao->save($object);
 
@@ -125,16 +125,12 @@ public function clear(): void
 
     private function supports(object $subscription): bool
     {
-        if ($subscription instanceof DAO\Subscription) {
-            return true;
-        }
-
         while ($subscription instanceof Subscription\Decorator) {
             $subscription = $subscription->subscription();
+        }
 
-            if ($subscription instanceof DAO\Subscription) {
-                return true;
-            }
+        if ($subscription instanceof DAO\Subscription) {
+            return true;
         }
 
         return false;
diff --git a/tests/Domain/EventSourcingTest.php b/tests/Domain/EventSourcingTest.php
index 85ac0bd0..bbe4da6e 100644
--- a/tests/Domain/EventSourcingTest.php
+++ b/tests/Domain/EventSourcingTest.php
@@ -637,7 +637,7 @@ class EventSourcedAggregateStub implements Event\Sourced\Aggregate
     use Aggregate\Identification;
 
     /**
-     * @var Event\Envelope[]
+     * @var array<int, Event\Envelope>
      */
     private array $appliedEvents = [];
 
@@ -671,12 +671,12 @@ public function appliedEvents(): array
 
     private function applyEvent1(Event1 $event): void
     {
-        $this->appliedEvents = [$event];
+        $this->appliedEvents[] = $event;
     }
 
     private function applyEvent2(Event2 $event): void
     {
-        $this->appliedEvents = [$event];
+        $this->appliedEvents[] = $event;
     }
 }