feat(server): add server lifecycle events (#175)

Signed-off-by: Edouard Courty <edouard.courty2@gmail.com>

src/Event/ErrorEvent.php

@@ -0,0 +1,61 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the official PHP MCP SDK.
+ *
+ * A collaboration between Symfony and the PHP Foundation.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Mcp\Event;
+
+use Mcp\Schema\JsonRpc\Error;
+use Mcp\Schema\JsonRpc\Request;
+use Mcp\Server\Session\SessionInterface;
+
+/**
+ * Event dispatched when an error occurs during request processing.
+ *
+ * Listeners can modify the error before it's sent to the client.
+ *
+ * @author Edouard Courty <edouard.courty2@gmail.com>
+ */
+final class ErrorEvent
+{
+    public function __construct(
+        private Error $error,
+        private readonly Request $request,
+        private readonly SessionInterface $session,
+        private readonly ?\Throwable $throwable,
+    ) {
+    }
+
+    public function getError(): Error
+    {
+        return $this->error;
+    }
+
+    public function setError(Error $error): void
+    {
+        $this->error = $error;
+    }
+
+    public function getRequest(): Request
+    {
+        return $this->request;
+    }
+
+    public function getThrowable(): ?\Throwable
+    {
+        return $this->throwable;
+    }
+
+    public function getSession(): SessionInterface
+    {
+        return $this->session;
+    }
+}

src/Event/NotificationEvent.php

@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the official PHP MCP SDK.
+ *
+ * A collaboration between Symfony and the PHP Foundation.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Mcp\Event;
+
+use Mcp\Schema\JsonRpc\Notification;
+use Mcp\Server\Session\SessionInterface;
+
+/**
+ * Event dispatched when any notification is received from the client.
+ *
+ * Listeners can modify the notification before it's processed by handlers.
+ *
+ * @author Edouard Courty <edouard.courty2@gmail.com>
+ */
+final class NotificationEvent
+{
+    public function __construct(
+        private Notification $notification,
+        private readonly SessionInterface $session,
+    ) {
+    }
+
+    public function getNotification(): Notification
+    {
+        return $this->notification;
+    }
+
+    public function setNotification(Notification $notification): void
+    {
+        $this->notification = $notification;
+    }
+
+    public function getSession(): SessionInterface
+    {
+        return $this->session;
+    }
+
+    public function getMethod(): string
+    {
+        return $this->notification::getMethod();
+    }
+}

src/Event/RequestEvent.php

@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the official PHP MCP SDK.
+ *
+ * A collaboration between Symfony and the PHP Foundation.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Mcp\Event;
+
+use Mcp\Schema\JsonRpc\Request;
+use Mcp\Server\Session\SessionInterface;
+
+/**
+ * Event dispatched when any request is received from the client.
+ *
+ * Listeners can modify the request before it's processed by handlers.
+ *
+ * @author Edouard Courty <edouard.courty2@gmail.com>
+ */
+final class RequestEvent
+{
+    public function __construct(
+        private Request $request,
+        private readonly SessionInterface $session,
+    ) {
+    }
+
+    public function getRequest(): Request
+    {
+        return $this->request;
+    }
+
+    public function setRequest(Request $request): void
+    {
+        $this->request = $request;
+    }
+
+    public function getSession(): SessionInterface
+    {
+        return $this->session;
+    }
+
+    public function getMethod(): string
+    {
+        return $this->request::getMethod();
+    }
+}

src/Event/ResponseEvent.php

@@ -0,0 +1,69 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the official PHP MCP SDK.
+ *
+ * A collaboration between Symfony and the PHP Foundation.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Mcp\Event;
+
+use Mcp\Schema\JsonRpc\Request;
+use Mcp\Schema\JsonRpc\Response;
+use Mcp\Server\Session\SessionInterface;
+
+/**
+ * Event dispatched when a successful response is ready to be sent to the client.
+ *
+ * Listeners can modify the response before it's sent.
+ *
+ * @author Edouard Courty <edouard.courty2@gmail.com>
+ */
+final class ResponseEvent
+{
+    /**
+     * @param Response<mixed> $response
+     */
+    public function __construct(
+        private Response $response,
+        private readonly Request $request,
+        private readonly SessionInterface $session,
+    ) {
+    }
+
+    /**
+     * @return Response<mixed>
+     */
+    public function getResponse(): Response
+    {
+        return $this->response;
+    }
+
+    /**
+     * @param Response<mixed> $response
+     */
+    public function setResponse(Response $response): void
+    {
+        $this->response = $response;
+    }
+
+    public function getRequest(): Request
+    {
+        return $this->request;
+    }
+
+    public function getSession(): SessionInterface
+    {
+        return $this->session;
+    }
+
+    public function getMethod(): string
+    {
+        return $this->request::getMethod();
+    }
+}