diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2c144a6..8c2921f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,21 @@ This file was introduced during the v1.7.x series. Structured entries below cove
 **v1.6.0 and later**; earlier releases can be reviewed via the
 [Git tag history](https://github.com/logiscape/mcp-sdk-php/tags).
 
+## [Unreleased]
+
+### Fixed
+
+- An `initialize` request carrying `_meta` no longer crashes the server with
+  a `TypeError`. `ClientRequest::createInitializeRequest()` passed the decoded
+  `_meta` array straight into the `?Meta` parameter of
+  `InitializeRequestParams`, so validation aborted with
+  `InitializeRequestParams::__construct(): Argument #4 ($_meta) must be of
+  type ?Mcp\Types\Meta, array given` before the handshake could be answered —
+  every request family other than `initialize` already converted `_meta`
+  through `extractMeta()`. Clients that attach trace context to the handshake
+  (SEP-414; Claude's web client sends `traceparent` / `baggage` there) could
+  not connect at all. Backported from the `v2` line.
+
 ## [1.7.4]
 
 ### Fixed
diff --git a/src/Types/ClientRequest.php b/src/Types/ClientRequest.php
index a2b09e1..74cfe63 100644
--- a/src/Types/ClientRequest.php
+++ b/src/Types/ClientRequest.php
@@ -185,11 +185,16 @@ private static function createInitializeRequest(array $params): self {
             throw new \InvalidArgumentException('protocolVersion is required for initialize.');
         }
 
+        // Wire `_meta` arrives as a decoded array — convert it like every
+        // other request family does. An initialize may legitimately carry
+        // `_meta` (SEP-414 trace context is allowed on any request), and
+        // passing the raw array to the typed ?Meta parameter crashed the
+        // session with a TypeError before the handshake could answer.
         $initializeParams = new InitializeRequestParams(
             protocolVersion: $params['protocolVersion'],
             capabilities: $capabilities,
             clientInfo: $clientInfo,
-            _meta: $params['_meta'] ?? null
+            _meta: self::extractMeta($params)
         );
 
         return new self(new InitializeRequest($initializeParams));
diff --git a/tests/Types/ClientRequestInitializeMetaTest.php b/tests/Types/ClientRequestInitializeMetaTest.php
new file mode 100644
index 0000000..6cfa9b5
--- /dev/null
+++ b/tests/Types/ClientRequestInitializeMetaTest.php
@@ -0,0 +1,76 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Mcp\Tests\Types;
+
+use Mcp\Types\ClientRequest;
+use Mcp\Types\InitializeRequest;
+use Mcp\Types\InitializeRequestParams;
+use Mcp\Types\Meta;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * An `initialize` request may carry `_meta` on the wire (SEP-414 trace
+ * context is allowed on any request). It arrives as a decoded array and has
+ * to be converted to `Meta` like every other request family does, otherwise
+ * the typed `?Meta` parameter of `InitializeRequestParams` raises a
+ * TypeError and the handshake dies before the session can answer.
+ */
+final class ClientRequestInitializeMetaTest extends TestCase
+{
+    public function testInitializeWithArrayMetaIsConvertedToMeta(): void
+    {
+        $request = ClientRequest::fromMethodAndParams('initialize', [
+            'protocolVersion' => '2025-06-18',
+            'capabilities' => [],
+            'clientInfo' => ['name' => 'test-client', 'version' => '1.0.0'],
+            '_meta' => [
+                'traceparent' => '00-0cb6548322595e40d670720bbba87ac4-fc8b88c394fe972b-01',
+                'progressToken' => 42,
+            ],
+        ]);
+
+        $inner = $request->getRequest();
+        $this->assertInstanceOf(InitializeRequest::class, $inner);
+
+        $params = $inner->params;
+        $this->assertInstanceOf(InitializeRequestParams::class, $params);
+        $this->assertInstanceOf(Meta::class, $params->_meta);
+        $this->assertSame(
+            '00-0cb6548322595e40d670720bbba87ac4-fc8b88c394fe972b-01',
+            $params->_meta->traceparent
+        );
+        $this->assertSame(42, $params->_meta->progressToken);
+
+        // The whole request must stay valid: validate() walks into _meta.
+        $request->validate();
+    }
+
+    public function testInitializeWithoutMetaKeepsNullMeta(): void
+    {
+        $request = ClientRequest::fromMethodAndParams('initialize', [
+            'protocolVersion' => '2025-06-18',
+            'capabilities' => [],
+            'clientInfo' => ['name' => 'test-client', 'version' => '1.0.0'],
+        ]);
+
+        $params = $request->getRequest()->params;
+        $this->assertInstanceOf(InitializeRequestParams::class, $params);
+        $this->assertNull($params->_meta);
+    }
+
+    public function testInitializeWithScalarMetaIsIgnoredRatherThanFatal(): void
+    {
+        $request = ClientRequest::fromMethodAndParams('initialize', [
+            'protocolVersion' => '2025-06-18',
+            'capabilities' => [],
+            'clientInfo' => ['name' => 'test-client', 'version' => '1.0.0'],
+            '_meta' => 'not-an-object',
+        ]);
+
+        $params = $request->getRequest()->params;
+        $this->assertInstanceOf(InitializeRequestParams::class, $params);
+        $this->assertNull($params->_meta);
+    }
+}