diff --git a/src/Handler/Pipeline.php b/src/Handler/Pipeline.php
index 00e3e8b2..4542f64f 100644
--- a/src/Handler/Pipeline.php
+++ b/src/Handler/Pipeline.php
@@ -15,7 +15,6 @@
  *
  * @psalm-type TLast = Closure(mixed ...): mixed
  *
- * @psalm-immutable
  * @internal
  * @psalm-internal Buggregator\Trap
  */
diff --git a/src/Sender/Console/Renderer/Monolog.php b/src/Sender/Console/Renderer/Monolog.php
index 9cd364dc..071c6f17 100644
--- a/src/Sender/Console/Renderer/Monolog.php
+++ b/src/Sender/Console/Renderer/Monolog.php
@@ -28,6 +28,8 @@ public function isSupport(Frame $frame): bool
 
     public function render(OutputInterface $output, Frame $frame): void
     {
+        \assert($frame instanceof Frame\Monolog);
+
         $payload = $frame->message;
         $levelColor = match (\strtolower($payload['level_name'])) {
             'notice', 'info' => 'blue',
@@ -41,7 +43,7 @@ public function render(OutputInterface $output, Frame $frame): void
             [
                 'date' => $payload['datetime'],
                 'channel' => $payload['channel'] ?? '',
-                'level' => $payload['level_name'] . '' ?? 'DEBUG',
+                'level' => $payload['level_name'] ?? 'DEBUG',
                 'levelColor' => $levelColor,
                 'messages' => \explode("\n", $payload['message']),
             ]
diff --git a/src/Sender/Console/Renderer/SentryEnvelope.php b/src/Sender/Console/Renderer/SentryEnvelope.php
index b34736d0..1491daf2 100644
--- a/src/Sender/Console/Renderer/SentryEnvelope.php
+++ b/src/Sender/Console/Renderer/SentryEnvelope.php
@@ -26,6 +26,8 @@ public function isSupport(Frame $frame): bool
 
     public function render(OutputInterface $output, Frame $frame): void
     {
+        \assert($frame instanceof Frame\Sentry\SentryEnvelope);
+
         Common::renderHeader1($output, 'SENTRY', 'ENVELOPE');
         Header::renderMessageHeader($output, $frame->headers + ['timestamp' => $frame->time->format('U.u')]);
 
diff --git a/src/Sender/Console/Renderer/SentryStore.php b/src/Sender/Console/Renderer/SentryStore.php
index 43f51143..fc9867d3 100644
--- a/src/Sender/Console/Renderer/SentryStore.php
+++ b/src/Sender/Console/Renderer/SentryStore.php
@@ -26,6 +26,8 @@ public function isSupport(Frame $frame): bool
 
     public function render(OutputInterface $output, Frame $frame): void
     {
+        \assert($frame instanceof Frame\Sentry\SentryStore);
+
         Common::renderHeader1($output, 'SENTRY');
 
         try {
diff --git a/src/Sender/Console/Renderer/Smtp.php b/src/Sender/Console/Renderer/Smtp.php
index b49b83c4..5b40302d 100644
--- a/src/Sender/Console/Renderer/Smtp.php
+++ b/src/Sender/Console/Renderer/Smtp.php
@@ -25,6 +25,8 @@ public function isSupport(Frame $frame): bool
 
     public function render(OutputInterface $output, Frame $frame): void
     {
+        \assert($frame instanceof Frame\Smtp);
+
         Common::renderHeader1($output, 'SMTP');
         Common::renderMetadata($output, [
             'Time' => $frame->time->format('Y-m-d H:i:s.u'),
diff --git a/src/Sender/Console/Renderer/VarDumper.php b/src/Sender/Console/Renderer/VarDumper.php
index db465489..6dcfb948 100644
--- a/src/Sender/Console/Renderer/VarDumper.php
+++ b/src/Sender/Console/Renderer/VarDumper.php
@@ -32,6 +32,8 @@ public function isSupport(Frame $frame): bool
 
     public function render(OutputInterface $output, Frame $frame): void
     {
+        \assert($frame instanceof Frame\VarDumper);
+
         $payload = @\unserialize(\base64_decode($frame->dump), ['allowed_classes' => [Data::class, Stub::class]]);
 
         // Impossible to decode the message, give up.
diff --git a/src/Sender/Console/RendererInterface.php b/src/Sender/Console/RendererInterface.php
index c9937263..c75e8e2d 100644
--- a/src/Sender/Console/RendererInterface.php
+++ b/src/Sender/Console/RendererInterface.php
@@ -18,7 +18,7 @@ interface RendererInterface
     public function isSupport(Frame $frame): bool;
 
     /**
-     * @param TFrame $frame
+     * @psalm-assert-if-true TFrame $frame
      */
     public function render(OutputInterface $output, Frame $frame): void;
 }
diff --git a/src/Sender/Console/Support/Files.php b/src/Sender/Console/Support/Files.php
index d3162bff..387e5376 100644
--- a/src/Sender/Console/Support/Files.php
+++ b/src/Sender/Console/Support/Files.php
@@ -55,6 +55,9 @@ public static function renderFile(
         $output->writeln("<bg=black;fg=magenta> └───┘</>  <fg=gray>$type</>");
     }
 
+    /**
+     * @param int<0, max>|null $size
+     */
     public static function normalizeSize(?int $size): ?string
     {
         if ($size === null) {
@@ -62,8 +65,11 @@ public static function normalizeSize(?int $size): ?string
         }
 
         $units = ['B', 'KiB', 'MiB', 'GiB', 'TiB', 'PiB'];
-        $power = \floor(\log($size, 1024));
+        $power = (int)\floor(\log($size, 1024));
         $float = $power > 0 ? \round($size / (1024 ** $power), 2) : $size;
-        return $float . ' ' . $units[$power];
+
+        \assert($power >= 0 && $power <= 5);
+
+        return \sprintf('%s %s', \number_format($float, 2), $units[$power]);
     }
 }
diff --git a/src/Socket/SocketStream.php b/src/Socket/SocketStream.php
index 5d0d3c34..aca31bfd 100644
--- a/src/Socket/SocketStream.php
+++ b/src/Socket/SocketStream.php
@@ -16,6 +16,7 @@
  * Use {@see Server::$clientInflector} to wrap {@see Client} into {@see self}.
  *
  * @internal
+ * @implements IteratorAggregate<int, string>
  */
 final class SocketStream implements IteratorAggregate, StreamClient
 {
diff --git a/src/Support/ProtobufCaster.php b/src/Support/ProtobufCaster.php
index 234e1558..a7d26023 100644
--- a/src/Support/ProtobufCaster.php
+++ b/src/Support/ProtobufCaster.php
@@ -173,19 +173,4 @@ class: $ed->getClass(),
 
         return $values;
     }
-
-    private static function extractViaPublic(Message $message, PublicDescriptor $descriptor): mixed
-    {
-        for ($i = 0; $i < $descriptor->getFieldCount(); $i++) {
-            /** @var FieldDescriptor $d */
-            $d = $descriptor->getField($i);
-            // $d->
-            if ($d->getType() !== GPBType::MESSAGE) {
-                continue;
-            }
-
-            // todo what can we do?
-            // $descriptor = $d->getMessageType();
-        }
-    }
 }
diff --git a/src/Support/StreamHelper.php b/src/Support/StreamHelper.php
index 5d2b40d4..02e6889f 100644
--- a/src/Support/StreamHelper.php
+++ b/src/Support/StreamHelper.php
@@ -56,6 +56,8 @@ public static function strpos(StreamInterface $stream, string $substr): int|fals
         }
 
         $stream->seek($caret, \SEEK_SET);
+
+        \assert($result >= 0);
         return $result;
     }
 
diff --git a/src/Traffic/Message/Headers.php b/src/Traffic/Message/Headers.php
index 4e96ab03..53b986f9 100644
--- a/src/Traffic/Message/Headers.php
+++ b/src/Traffic/Message/Headers.php
@@ -30,10 +30,6 @@ public function hasHeader(string $header): bool
      */
     public function getHeader(string $header): array
     {
-        if (!\is_string($header)) {
-            throw new \InvalidArgumentException('Header name must be an RFC 7230 compatible string');
-        }
-
         $header = \strtr($header, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz');
         if (!isset($this->headerNames[$header])) {
             return [];
@@ -66,7 +62,7 @@ public function withHeader(string $header, $value): static
 
     public function withAddedHeader(string $header, string $value): static
     {
-        if (!\is_string($header) || '' === $header) {
+        if ('' === $header) {
             throw new \InvalidArgumentException('Header name must be an RFC 7230 compatible string');
         }
 
@@ -78,10 +74,6 @@ public function withAddedHeader(string $header, string $value): static
 
     public function withoutHeader(string $header): static
     {
-        if (!\is_string($header)) {
-            throw new \InvalidArgumentException('Header name must be an RFC 7230 compatible string');
-        }
-
         $normalized = \strtr($header, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz');
         if (!isset($this->headerNames[$normalized])) {
             return $this;
diff --git a/src/Traffic/Message/Smtp.php b/src/Traffic/Message/Smtp.php
index 996019cc..12d9c3e5 100644
--- a/src/Traffic/Message/Smtp.php
+++ b/src/Traffic/Message/Smtp.php
@@ -17,13 +17,6 @@
  * @psalm-import-type FieldDataArray from Field
  * @psalm-import-type FileDataArray from File
  *
- * @psalm-type SmtpDataArray = array{
- *     protocol: array<string, string|list<string>>,
- *     headers: array<string, list<string>>,
- *     messages: array<int, FieldDataArray>,
- *     attachments: array<int, FileDataArray>
- * }
- *
  * @internal
  */
 final class Smtp implements JsonSerializable
@@ -31,10 +24,10 @@ final class Smtp implements JsonSerializable
     use Headers;
     use StreamBody;
 
-    /** @var Field[] */
+    /** @var list<Field> */
     private array $messages = [];
 
-    /** @var File[] */
+    /** @var list<File> */
     private array $attachments = [];
 
     /**
@@ -57,9 +50,6 @@ public static function create(array $protocol, array $headers): self
         return new self($protocol, $headers);
     }
 
-    /**
-     * @param SmtpDataArray $data
-     */
     public static function fromArray(array $data): self
     {
         $self = new self($data['protocol'], $data['headers']);
@@ -73,9 +63,6 @@ public static function fromArray(array $data): self
         return $self;
     }
 
-    /**
-     * @return SmtpDataArray
-     */
     public function jsonSerialize(): array
     {
         return [
diff --git a/src/Traffic/StreamClient.php b/src/Traffic/StreamClient.php
index 717638af..4747779f 100644
--- a/src/Traffic/StreamClient.php
+++ b/src/Traffic/StreamClient.php
@@ -12,6 +12,7 @@
  * Simple abstraction over a client two-way stream.
  * @internal
  * @psalm-internal Buggregator\Trap\Traffic
+ * @extends \IteratorAggregate<int, string>
  */
 interface StreamClient extends \IteratorAggregate
 {