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soyukasoyuka
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fix(mcp): list tools/resources at request time
The SDK Builder runs MCP loaders once, when mcp.server is first built, into a shared registry that tools/list reads from. Under a persistent runtime (FrankenPHP worker mode) that single build can capture an empty registry (cold metadata cache) and stays empty for the whole process, so tools/list returns []. tools/call keeps working because the request-time Handler resolves operations from metadata directly. Add a ListHandler (tagged mcp.request_handler, so it takes precedence over the SDK's registry-backed handler) that builds tools/list and resources/list from the api-platform Loader on each request, keeping discovery as resilient as invocation. Closes #8370
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‎src/Mcp/Server/ListHandler.php‎

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<?php
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/*
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* This file is part of the API Platform project.
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*
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* (c) Kévin Dunglas <dunglas@gmail.com>
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*/
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declare(strict_types=1);
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namespace ApiPlatform\Mcp\Server;
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use Mcp\Capability\Registry;
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use Mcp\Capability\Registry\Loader\LoaderInterface;
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use Mcp\Schema\JsonRpc\Request;
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use Mcp\Schema\JsonRpc\Response;
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use Mcp\Schema\Request\ListResourcesRequest;
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use Mcp\Schema\Request\ListToolsRequest;
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use Mcp\Schema\Result\ListResourcesResult;
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use Mcp\Schema\Result\ListToolsResult;
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use Mcp\Server\Handler\Request\RequestHandlerInterface;
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use Mcp\Server\Session\SessionInterface;
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/**
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* Lists MCP tools and resources from API Platform metadata at request time.
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*
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* The SDK's built-in list handlers read from a registry populated once, when mcp.server is
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* built. Under a persistent runtime (e.g. FrankenPHP worker mode) that single build can capture
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* an empty registry — leaving tools/list empty for the whole process while tools/call keeps
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* working through the request-time {@see Handler}. Rebuilding from the loader on each request
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* keeps discovery and invocation consistent.
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*
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* @experimental
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*
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* @implements RequestHandlerInterface<ListToolsResult|ListResourcesResult>
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*/
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final class ListHandler implements RequestHandlerInterface
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{
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public function __construct(
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private readonly LoaderInterface $loader,
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private readonly int $pageSize = 20,
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) {
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}
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public function supports(Request $request): bool
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{
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return $request instanceof ListToolsRequest || $request instanceof ListResourcesRequest;
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}
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/**
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* @return Response<ListToolsResult|ListResourcesResult>
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*/
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public function handle(Request $request, SessionInterface $session): Response
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{
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$registry = new Registry();
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$this->loader->load($registry);
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if ($request instanceof ListResourcesRequest) {
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$page = $registry->getResources($this->pageSize, $request->cursor);
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$result = new ListResourcesResult($page->references, $page->nextCursor);
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} else {
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\assert($request instanceof ListToolsRequest);
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$page = $registry->getTools($this->pageSize, $request->cursor);
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$result = new ListToolsResult($page->references, $page->nextCursor);
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}
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return new Response($request->getId(), $result);
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}
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}

‎src/Mcp/Tests/Server/ListHandlerTest.php‎

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<?php
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/*
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* This file is part of the API Platform project.
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*
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* (c) Kévin Dunglas <dunglas@gmail.com>
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*/
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declare(strict_types=1);
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namespace ApiPlatform\Mcp\Tests\Server;
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use ApiPlatform\JsonSchema\Schema;
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use ApiPlatform\JsonSchema\SchemaFactoryInterface;
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use ApiPlatform\Mcp\Capability\Registry\Loader;
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use ApiPlatform\Mcp\Server\ListHandler;
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use ApiPlatform\Metadata\ApiResource;
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use ApiPlatform\Metadata\McpResource;
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use ApiPlatform\Metadata\McpTool;
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use ApiPlatform\Metadata\Resource\Factory\ResourceMetadataCollectionFactoryInterface;
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use ApiPlatform\Metadata\Resource\Factory\ResourceNameCollectionFactoryInterface;
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use ApiPlatform\Metadata\Resource\ResourceMetadataCollection;
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use ApiPlatform\Metadata\Resource\ResourceNameCollection;
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use Mcp\Schema\Request\ListResourcesRequest;
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use Mcp\Schema\Request\ListToolsRequest;
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use Mcp\Schema\Result\ListResourcesResult;
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use Mcp\Schema\Result\ListToolsResult;
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use Mcp\Server\Session\SessionInterface;
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use PHPUnit\Framework\TestCase;
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class ListHandlerTest extends TestCase
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{
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public function testListToolsIsBuiltFromMetadataAtRequestTime(): void
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{
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$inputSchema = new Schema(Schema::VERSION_JSON_SCHEMA);
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unset($inputSchema['$schema']);
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$inputSchema['type'] = 'object';
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$inputSchema['properties'] = ['query' => ['type' => 'string']];
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$schemaFactory = $this->createMock(SchemaFactoryInterface::class);
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$schemaFactory->method('buildSchema')->willReturn($inputSchema);
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$mcpTool = new McpTool(
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name: 'search',
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description: 'Search things',
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structuredContent: false,
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class: \stdClass::class,
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);
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$resource = (new ApiResource(class: \stdClass::class))->withMcp(['search' => $mcpTool]);
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$handler = new ListHandler($this->createLoader($resource, $schemaFactory));
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$request = (new ListToolsRequest())->withId(1);
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$response = $handler->handle($request, $this->createMock(SessionInterface::class));
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$result = $response->result;
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$this->assertInstanceOf(ListToolsResult::class, $result);
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$this->assertCount(1, $result->tools);
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$this->assertSame('search', $result->tools[0]->name);
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}
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public function testListResourcesIsBuiltFromMetadataAtRequestTime(): void
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{
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$mcpResource = new McpResource(
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uri: 'dummy://docs',
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name: 'docs',
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description: 'Documentation resource',
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mimeType: 'text/plain',
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class: \stdClass::class,
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);
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$resource = (new ApiResource(class: \stdClass::class))->withMcp(['docs' => $mcpResource]);
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$handler = new ListHandler($this->createLoader($resource, $this->createMock(SchemaFactoryInterface::class)));
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$request = (new ListResourcesRequest())->withId(1);
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$response = $handler->handle($request, $this->createMock(SessionInterface::class));
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$result = $response->result;
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$this->assertInstanceOf(ListResourcesResult::class, $result);
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$this->assertCount(1, $result->resources);
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$this->assertSame('dummy://docs', $result->resources[0]->uri);
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}
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public function testSupportsListRequests(): void
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{
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$handler = new ListHandler($this->createMock(\Mcp\Capability\Registry\Loader\LoaderInterface::class));
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$this->assertTrue($handler->supports(new ListToolsRequest()));
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$this->assertTrue($handler->supports(new ListResourcesRequest()));
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}
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private function createLoader(ApiResource $resource, SchemaFactoryInterface $schemaFactory): Loader
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{
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$nameCollectionFactory = $this->createMock(ResourceNameCollectionFactoryInterface::class);
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$nameCollectionFactory->method('create')->willReturn(new ResourceNameCollection([\stdClass::class]));
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$metadataCollectionFactory = $this->createMock(ResourceMetadataCollectionFactoryInterface::class);
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$metadataCollectionFactory->method('create')->willReturn(new ResourceMetadataCollection(\stdClass::class, [$resource]));
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return new Loader($nameCollectionFactory, $metadataCollectionFactory, $schemaFactory);
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}
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}

‎src/Symfony/Bundle/Resources/config/mcp/mcp.php‎

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use ApiPlatform\Mcp\JsonSchema\SchemaFactory;
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use ApiPlatform\Mcp\Metadata\Operation\Factory\OperationMetadataFactory;
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use ApiPlatform\Mcp\Routing\IriConverter;
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use ApiPlatform\Mcp\Server\ListHandler;
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use ApiPlatform\Mcp\State\ToolProvider;
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return static function (ContainerConfigurator $container) {
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])
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->tag('mcp.loader');
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// Serves tools/list and resources/list from metadata at request time, so discovery survives
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// a persistent runtime (e.g. FrankenPHP worker mode) where the SDK registry is built once and
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// may capture an empty state. Takes precedence over the SDK's registry-backed list handlers.
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$services->set('api_platform.mcp.list_handler', ListHandler::class)
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->args([
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service('api_platform.mcp.loader'),
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])
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->tag('mcp.request_handler');
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$services->set('api_platform.mcp.iri_converter', IriConverter::class)
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->decorate('api_platform.iri_converter', null, 300)
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->args([

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