Conditionally call Builder->setLogger() only when MonologBundle exists, and handle nullable logger in McpCommand/McpController by conditionally passing it to Transports.

  When MonologBundle is absent, Server and Transports use their default NullLogger.

Author: camilleislasse

src/mcp-bundle/config/services.php

@@ -25,17 +25,21 @@
         ;
     }
 
-    $container->services()
+    $builderDefinition = $container->services()
         ->set('mcp.server.builder', Builder::class)
             ->factory([Server::class, 'builder'])
             ->call('setServerInfo', [param('mcp.app'), param('mcp.version')])
             ->call('setPaginationLimit', [param('mcp.pagination_limit')])
             ->call('setInstructions', [param('mcp.instructions')])
-            ->call('setLogger', [service('monolog.logger.mcp')->nullOnInvalid()])
             ->call('setEventDispatcher', [service('event_dispatcher')])
             ->call('setSession', [service('mcp.session.store')])
-            ->call('setDiscovery', [param('kernel.project_dir'), param('mcp.discovery.scan_dirs'), param('mcp.discovery.exclude_dirs')])
+            ->call('setDiscovery', [param('kernel.project_dir'), param('mcp.discovery.scan_dirs'), param('mcp.discovery.exclude_dirs')]);
 
+    if (class_exists(MonologBundle::class)) {
+        $builderDefinition->call('setLogger', [service('monolog.logger.mcp')]);
+    }
+
+    $container->services()
         ->set('mcp.server', Server::class)
             ->factory([service('mcp.server.builder'), 'build'])
 

src/mcp-bundle/src/Command/McpCommand.php

@@ -24,14 +24,16 @@ class McpCommand extends Command
 {
     public function __construct(
         private readonly Server $server,
-        private readonly LoggerInterface $logger,
+        private readonly ?LoggerInterface $logger = null,
     ) {
         parent::__construct();
     }
 
     protected function execute(InputInterface $input, OutputInterface $output): int
     {
-        $transport = new StdioTransport(logger: $this->logger);
+        $transport = $this->logger
+            ? new StdioTransport(logger: $this->logger)
+            : new StdioTransport();
         $this->server->run($transport);
 
         return Command::SUCCESS;

src/mcp-bundle/src/Controller/McpController.php

@@ -35,12 +35,18 @@ public function __construct(
 
     public function handle(Request $request): Response
     {
-        $transport = new StreamableHttpTransport(
-            $this->httpMessageFactory->createRequest($request),
-            $this->responseFactory,
-            $this->streamFactory,
-            logger: $this->logger,
-        );
+        $transport = $this->logger
+            ? new StreamableHttpTransport(
+                $this->httpMessageFactory->createRequest($request),
+                $this->responseFactory,
+                $this->streamFactory,
+                logger: $this->logger,
+            )
+            : new StreamableHttpTransport(
+                $this->httpMessageFactory->createRequest($request),
+                $this->responseFactory,
+                $this->streamFactory,
+            );
 
         return $this->httpFoundationFactory->createResponse(
             $this->server->run($transport),