feat: add completion/complete handler, centralize provider logic, and move completion capability (#97)

src/Server/Builder.php

@@ -12,13 +12,13 @@
 namespace Mcp\Server;
 
 use Mcp\Capability\Attribute\CompletionProvider;
+use Mcp\Capability\Completion\EnumCompletionProvider;
+use Mcp\Capability\Completion\ListCompletionProvider;
 use Mcp\Capability\Discovery\CachedDiscoverer;
 use Mcp\Capability\Discovery\Discoverer;
 use Mcp\Capability\Discovery\DocBlockParser;
 use Mcp\Capability\Discovery\HandlerResolver;
 use Mcp\Capability\Discovery\SchemaGenerator;
-use Mcp\Capability\Prompt\Completion\EnumCompletionProvider;
-use Mcp\Capability\Prompt\Completion\ListCompletionProvider;
 use Mcp\Capability\Prompt\PromptGetter;
 use Mcp\Capability\Prompt\PromptGetterInterface;
 use Mcp\Capability\Registry;

src/Server/Handler/JsonRpcHandler.php

@@ -11,6 +11,7 @@
 
 namespace Mcp\Server\Handler;
 
+use Mcp\Capability\Completion\Completer;
 use Mcp\Capability\Prompt\PromptGetterInterface;
 use Mcp\Capability\Registry\ReferenceProviderInterface;
 use Mcp\Capability\Registry\ReferenceRegistryInterface;
@@ -89,6 +90,7 @@ class JsonRpcHandler
                 new Handler\Request\ListResourceTemplatesHandler($referenceProvider, $paginationLimit),
                 new Handler\Request\CallToolHandler($toolCaller, $logger),
                 new Handler\Request\ListToolsHandler($referenceProvider, $paginationLimit),
+                new Handler\Request\CompletionCompleteHandler(new Completer($referenceProvider)),
             ],
             logger: $logger,
         );

src/Server/Handler/Request/CompletionCompleteHandler.php

@@ -0,0 +1,52 @@
+<?php
+
+/*
+ * 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\Server\Handler\Request;
+
+use Mcp\Capability\Completion\CompleterInterface;
+use Mcp\Exception\ExceptionInterface;
+use Mcp\Schema\JsonRpc\Error;
+use Mcp\Schema\JsonRpc\HasMethodInterface;
+use Mcp\Schema\JsonRpc\Response;
+use Mcp\Schema\Request\CompletionCompleteRequest;
+use Mcp\Server\Handler\MethodHandlerInterface;
+use Mcp\Server\Session\SessionInterface;
+
+/**
+ * Handles completion/complete requests.
+ *
+ * @author Kyrian Obikwelu <koshnawaza@gmail.com>
+ */
+final class CompletionCompleteHandler implements MethodHandlerInterface
+{
+    public function __construct(
+        private readonly CompleterInterface $completer,
+    ) {
+    }
+
+    public function supports(HasMethodInterface $message): bool
+    {
+        return $message instanceof CompletionCompleteRequest;
+    }
+
+    public function handle(CompletionCompleteRequest|HasMethodInterface $message, SessionInterface $session): Response|Error
+    {
+        \assert($message instanceof CompletionCompleteRequest);
+
+        try {
+            $result = $this->completer->complete($message);
+        } catch (ExceptionInterface) {
+            return Error::forInternalError('Error while handling completion request', $message->getId());
+        }
+
+        return new Response($message->getId(), $result);
+    }
+}