Registry Architecture Refactoring - Enhanced Separation of Concerns (#46)

* refactor: Separate Registry concerns following SOLID principles [WIP]

- Extract ReferenceProvider and ReferenceRegistryInterface interfaces
- Create DefaultToolExecutor with ReferenceHandlerInterface
- Remove execution responsibility from Registry class
- Enable custom handler and executor implementations

* refactor: implement SOLID principles with separated execution concerns

* Create DefaultResourceReader, DefaultPromptGetter
* Refactor JsonRpc Handler and RequestHandlers to use dedicated executors
* Update ServerBuilder to support custom executors via dependency injection

* chore: remove extra comments

* feat: introduce DispatchableRegistry for enhanced tool and resource management

* refactor: use proper interfaces

* refactor: implement HandlerInterface for improved abstraction and flexibility

* test: add unit tests for DispatchableRegistry and Registry classes

* refactor: cover with unit tests Resource reader, Prompt getter and Tool executor

* cs fix

* phpstan fix

* test: add unit tests for CallToolHandler, GetPromptHandler, PingHandler, and ReadResourceHandler

* refactor: revert Handler

* chore: remove style guide for tests

* refactor: remove "Default" prefix from classes

* refactor: remove DispatchableRegistry

* refactor: use package specific exception classes

* refactor: remove DispatchableRegistry

* refactor: add logger support to PromptGetter and ResourceReader classes

* Update src/Capability/Prompt/PromptGetter.php

Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>

* refactor: Use FQN for Resource class to avoid cs-fixer misinterpreting it as `resource`

* refactor: rename ToolExecutor to ToolCaller and related classes for clarity and consistency

* refactor: add missed docblock

* refactor: rename ToolExecutor references to ToolCaller

* refactor: rename ToolCallerTest property and variable references

* cs fix

* ignore some phpstan errors

---------

Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>

src/Server/RequestHandler/CallToolHandler.php

@@ -11,13 +11,12 @@
 
 namespace Mcp\Server\RequestHandler;
 
-use Mcp\Capability\Registry;
+use Mcp\Capability\Tool\ToolCallerInterface;
 use Mcp\Exception\ExceptionInterface;
 use Mcp\Schema\JsonRpc\Error;
 use Mcp\Schema\JsonRpc\HasMethodInterface;
 use Mcp\Schema\JsonRpc\Response;
 use Mcp\Schema\Request\CallToolRequest;
-use Mcp\Schema\Result\CallToolResult;
 use Mcp\Server\MethodHandlerInterface;
 use Psr\Log\LoggerInterface;
 use Psr\Log\NullLogger;
@@ -29,7 +28,7 @@ use Psr\Log\NullLogger;
 final class CallToolHandler implements MethodHandlerInterface
 {
     public function __construct(
-        private readonly Registry $registry,
+        private readonly ToolCallerInterface $toolCaller,
         private readonly LoggerInterface $logger = new NullLogger(),
     ) {
     }
@@ -44,16 +43,19 @@ final class CallToolHandler implements MethodHandlerInterface
         \assert($message instanceof CallToolRequest);
 
         try {
-            $content = $this->registry->handleCallTool($message->name, $message->arguments);
+            $content = $this->toolCaller->call($message);
         } catch (ExceptionInterface $exception) {
-            $this->logger->error(\sprintf('Error while executing tool "%s": "%s".', $message->name, $exception->getMessage()), [
-                'tool' => $message->name,
-                'arguments' => $message->arguments,
-            ]);
+            $this->logger->error(
+                \sprintf('Error while executing tool "%s": "%s".', $message->name, $exception->getMessage()),
+                [
+                    'tool' => $message->name,
+                    'arguments' => $message->arguments,
+                ],
+            );
 
             return Error::forInternalError('Error while executing tool', $message->getId());
         }
 
-        return new Response($message->getId(), new CallToolResult($content));
+        return new Response($message->getId(), $content);
     }
 }

src/Server/RequestHandler/GetPromptHandler.php

@@ -11,13 +11,12 @@
 
 namespace Mcp\Server\RequestHandler;
 
-use Mcp\Capability\Registry;
+use Mcp\Capability\Prompt\PromptGetterInterface;
 use Mcp\Exception\ExceptionInterface;
 use Mcp\Schema\JsonRpc\Error;
 use Mcp\Schema\JsonRpc\HasMethodInterface;
 use Mcp\Schema\JsonRpc\Response;
 use Mcp\Schema\Request\GetPromptRequest;
-use Mcp\Schema\Result\GetPromptResult;
 use Mcp\Server\MethodHandlerInterface;
 
 /**
@@ -26,7 +25,7 @@ use Mcp\Server\MethodHandlerInterface;
 final class GetPromptHandler implements MethodHandlerInterface
 {
     public function __construct(
-        private readonly Registry $registry,
+        private readonly PromptGetterInterface $promptGetter,
     ) {
     }
 
@@ -40,11 +39,11 @@ final class GetPromptHandler implements MethodHandlerInterface
         \assert($message instanceof GetPromptRequest);
 
         try {
-            $messages = $this->registry->handleGetPrompt($message->name, $message->arguments);
+            $messages = $this->promptGetter->get($message);
         } catch (ExceptionInterface) {
             return Error::forInternalError('Error while handling prompt', $message->getId());
         }
 
-        return new Response($message->getId(), new GetPromptResult($messages));
+        return new Response($message->getId(), $messages);
     }
 }

src/Server/RequestHandler/ListPromptsHandler.php

@@ -11,7 +11,7 @@
 
 namespace Mcp\Server\RequestHandler;
 
-use Mcp\Capability\Registry;
+use Mcp\Capability\Registry\ReferenceProviderInterface;
 use Mcp\Schema\JsonRpc\HasMethodInterface;
 use Mcp\Schema\JsonRpc\Response;
 use Mcp\Schema\Request\ListPromptsRequest;
@@ -24,7 +24,7 @@ use Mcp\Server\MethodHandlerInterface;
 final class ListPromptsHandler implements MethodHandlerInterface
 {
     public function __construct(
-        private readonly Registry $registry,
+        private readonly ReferenceProviderInterface $registry,
         private readonly int $pageSize = 20,
     ) {
     }

src/Server/RequestHandler/ListResourcesHandler.php

@@ -11,7 +11,7 @@
 
 namespace Mcp\Server\RequestHandler;
 
-use Mcp\Capability\Registry;
+use Mcp\Capability\Registry\ReferenceProviderInterface;
 use Mcp\Schema\JsonRpc\HasMethodInterface;
 use Mcp\Schema\JsonRpc\Response;
 use Mcp\Schema\Request\ListResourcesRequest;
@@ -24,7 +24,7 @@ use Mcp\Server\MethodHandlerInterface;
 final class ListResourcesHandler implements MethodHandlerInterface
 {
     public function __construct(
-        private readonly Registry $registry,
+        private readonly ReferenceProviderInterface $registry,
         private readonly int $pageSize = 20,
     ) {
     }

src/Server/RequestHandler/ListToolsHandler.php

@@ -11,7 +11,7 @@
 
 namespace Mcp\Server\RequestHandler;
 
-use Mcp\Capability\Registry;
+use Mcp\Capability\Registry\ReferenceProviderInterface;
 use Mcp\Schema\JsonRpc\HasMethodInterface;
 use Mcp\Schema\JsonRpc\Response;
 use Mcp\Schema\Request\ListToolsRequest;
@@ -25,7 +25,7 @@ use Mcp\Server\MethodHandlerInterface;
 final class ListToolsHandler implements MethodHandlerInterface
 {
     public function __construct(
-        private readonly Registry $registry,
+        private readonly ReferenceProviderInterface $registry,
         private readonly int $pageSize = 20,
     ) {
     }

src/Server/RequestHandler/ReadResourceHandler.php

@@ -11,14 +11,13 @@
 
 namespace Mcp\Server\RequestHandler;
 
-use Mcp\Capability\Registry;
+use Mcp\Capability\Resource\ResourceReaderInterface;
 use Mcp\Exception\ExceptionInterface;
 use Mcp\Exception\ResourceNotFoundException;
 use Mcp\Schema\JsonRpc\Error;
 use Mcp\Schema\JsonRpc\HasMethodInterface;
 use Mcp\Schema\JsonRpc\Response;
 use Mcp\Schema\Request\ReadResourceRequest;
-use Mcp\Schema\Result\ReadResourceResult;
 use Mcp\Server\MethodHandlerInterface;
 
 /**
@@ -27,7 +26,7 @@ use Mcp\Server\MethodHandlerInterface;
 final class ReadResourceHandler implements MethodHandlerInterface
 {
     public function __construct(
-        private readonly Registry $registry,
+        private readonly ResourceReaderInterface $resourceReader,
     ) {
     }
 
@@ -41,13 +40,13 @@ final class ReadResourceHandler implements MethodHandlerInterface
         \assert($message instanceof ReadResourceRequest);
 
         try {
-            $contents = $this->registry->handleReadResource($message->uri);
+            $contents = $this->resourceReader->read($message);
         } catch (ResourceNotFoundException $e) {
             return new Error($message->getId(), Error::RESOURCE_NOT_FOUND, $e->getMessage());
         } catch (ExceptionInterface) {
             return Error::forInternalError('Error while reading resource', $message->getId());
         }
 
-        return new Response($message->getId(), new ReadResourceResult($contents));
+        return new Response($message->getId(), $contents);
     }
 }