Fix: Add support for notifications/initialized method (#41)

Author: kargnas

src/Data/Resources/JsonRpc/JsonRpcResultResource.php

@@ -19,16 +19,17 @@ class JsonRpcResultResource
      * The identifier established by the client for the JSON-RPC request.
      * Must be the same as the value of the id member in the Request Object.
      * If there was an error in detecting the id in the Request object (e.g. Parse error/Invalid Request), it MUST be Null.
+     * For notifications, this is null as notifications don't have IDs.
      */
-    protected string|int $id;
+    protected string|int|null $id;
 
     /**
      * JsonRpcResultResource constructor.
      *
-     * @param  string|int  $id  The identifier established by the client.
+     * @param  string|int|null  $id  The identifier established by the client. Null for notifications.
      * @param  array|stdClass  $result  The result data from the method execution.
      */
-    public function __construct(string|int $id, array|stdClass $result)
+    public function __construct(string|int|null $id, array|stdClass $result)
     {
         $this->result = $result;
         $this->id = $id;
@@ -37,7 +38,7 @@ public function __construct(string|int $id, array|stdClass $result)
     /**
      * Formats the data into a JSON-RPC 2.0 compliant response array.
      *
-     * @return array{jsonrpc: string, id: string|int, result: array|stdClass} The JSON-RPC response array.
+     * @return array{jsonrpc: string, id: string|int|null, result: array|stdClass} The JSON-RPC response array.
      */
     public function toResponse(): array
     {

src/Protocol/MCPProtocol.php

@@ -3,7 +3,6 @@
 namespace OPGG\LaravelMcpServer\Protocol;
 
 use Exception;
-use Illuminate\Support\Str;
 use OPGG\LaravelMcpServer\Data\ProcessMessageData;
 use OPGG\LaravelMcpServer\Data\Requests\NotificationData;
 use OPGG\LaravelMcpServer\Data\Requests\RequestData;
@@ -196,14 +195,13 @@ private function sendSSEMessage(string $clientId, array|JsonRpcResultResource|Js
      */
     private function processNotification(string $clientId, NotificationData $notificationData): ProcessMessageData
     {
-        // todo:: processNotification currently not implemented
         $method = $notificationData->method;
-        $handler = $this->requestHandlers[$method] ?? null;
+        $handler = $this->notificationHandlers[$method] ?? null;
         if ($handler) {
-            $result = $handler->execute(method: $notificationData->method, params: $notificationData->params);
+            $result = $handler->execute(params: $notificationData->params);
             $messageType = $handler->getMessageType($notificationData->params);
 
-            $resultResource = new JsonRpcResultResource(id: Str::uuid()->toString(), result: $result);
+            $resultResource = new JsonRpcResultResource(id: null, result: $result);
             $processMessageData = new ProcessMessageData(messageType: $messageType, resource: $resultResource);
 
             if ($processMessageData->isSSEMessage()) {

src/Server/MCPServer.php

@@ -10,6 +10,7 @@
 use OPGG\LaravelMcpServer\Protocol\Handlers\NotificationHandler;
 use OPGG\LaravelMcpServer\Protocol\Handlers\RequestHandler;
 use OPGG\LaravelMcpServer\Protocol\MCPProtocol;
+use OPGG\LaravelMcpServer\Server\Notification\InitializedHandler;
 use OPGG\LaravelMcpServer\Server\Request\InitializeHandler;
 use OPGG\LaravelMcpServer\Server\Request\PingHandler;
 use OPGG\LaravelMcpServer\Server\Request\PromptsGetHandler;
@@ -85,6 +86,9 @@ public function __construct(MCPProtocol $protocol, array $serverInfo, ?ServerCap
 
         // Initialize Default Handlers
         $this->registerRequestHandler(new PingHandler);
+
+        // Register notification handlers
+        $this->registerNotificationHandler(new InitializedHandler);
     }
 
     /**

src/Server/Notification/InitializedHandler.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace OPGG\LaravelMcpServer\Server\Notification;
+
+use OPGG\LaravelMcpServer\Enums\ProcessMessageType;
+use OPGG\LaravelMcpServer\Protocol\Handlers\NotificationHandler;
+use stdClass;
+
+class InitializedHandler extends NotificationHandler
+{
+    protected const MESSAGE_TYPE = ProcessMessageType::HTTP;
+
+    protected const HANDLE_METHOD = 'notifications/initialized';
+
+    public function execute(?array $params = null): array|stdClass
+    {
+        // The 'notifications/initialized' is sent by the client after the initialization
+        // handshake is complete. This is purely for acknowledgment - no response is needed.
+        // We return an empty array to indicate successful processing.
+        return [];
+    }
+}