refactor: Replace json with IDataNode in DebugEngine

**Changes:**
- DebugEngine.h: Replace `json` with `std::unique_ptr<IDataNode>`
  - engineConfig: json → std::unique_ptr<IDataNode>
  - getDetailedStatus(): json → std::unique_ptr<IDataNode>

- DebugEngine.cpp: Update implementations
  - Include JsonDataNode/JsonDataValue headers
  - getDetailedStatus() returns JsonDataNode wrapper
  - Message logging adapted for IDataNode (check nullptr instead of dump())
  - Keep json internally for convenience (converted to IDataNode when needed)

**Architecture:**
- Engine uses IDataNode abstraction for external interfaces
- Internal JSON usage preserved for convenience
- Compatible with new IDataTree system

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

include/grove/DebugEngine.h

@@ -7,13 +7,11 @@
 #include <thread>
 #include <atomic>
 #include <spdlog/spdlog.h>
-#include <nlohmann/json.hpp>
 
 #include "IEngine.h"
 #include "IModuleSystem.h"
 #include "IIO.h"
-
+#include "IDataNode.h"
-using json = nlohmann::json;
 
 namespace grove {
 
@@ -48,7 +46,7 @@ private:
     size_t frameCount = 0;
 
     // Configuration
-    json engineConfig;
+    std::unique_ptr<IDataNode> engineConfig;
 
     // Helper methods
     void logEngineStart();
@@ -82,7 +80,7 @@ public:
     void resumeExecution();
     void stepSingleFrame();
     bool isPaused() const;
-    json getDetailedStatus() const;
+    std::unique_ptr<IDataNode> getDetailedStatus() const;
     void setLogLevel(spdlog::level::level_enum level);
 };
 

src/DebugEngine.cpp

@@ -1,4 +1,7 @@
 #include <grove/DebugEngine.h>
+#include <grove/JsonDataNode.h>
+#include <grove/JsonDataValue.h>
+#include <nlohmann/json.hpp>
 #include <fstream>
 #include <filesystem>
 #include <spdlog/sinks/stdout_color_sinks.h>
@@ -6,6 +9,8 @@
 
 namespace grove {
 
+using json = nlohmann::json;
+
 DebugEngine::DebugEngine() {
     // Create comprehensive logger with multiple sinks
     auto console_sink = std::make_shared<spdlog::sinks::stdout_color_sink_mt>();
@@ -294,7 +299,7 @@ bool DebugEngine::isPaused() const {
     return paused;
 }
 
-json DebugEngine::getDetailedStatus() const {
+std::unique_ptr<IDataNode> DebugEngine::getDetailedStatus() const {
     logger->debug("📊 Detailed status requested");
 
     json status = {
@@ -315,8 +320,8 @@ json DebugEngine::getDetailedStatus() const {
         status["average_fps"] = frameCount / totalTime;
     }
 
-    logger->trace("📄 Status JSON: {}", status.dump());
+    logger->trace("📄 Status: {}", status.dump());
-    return status;
+    return std::make_unique<JsonDataNode>("status", status);
 }
 
 void DebugEngine::setLogLevel(spdlog::level::level_enum level) {
@@ -425,8 +430,9 @@ void DebugEngine::processClientMessages() {
             for (int j = 0; j < messagesToProcess; ++j) {
                 try {
                     auto message = socket->pullMessage();
-                    logger->debug("📩 Client {} message: topic='{}', data size={}",
+                    std::string dataPreview = message.data ? message.data->getData()->toString() : "null";
-                                i, message.topic, message.data.dump().size());
+                    logger->debug("📩 Client {} message: topic='{}', data present={}",
+                                i, message.topic, message.data != nullptr);
 
                     // TODO: Route message to appropriate module or process it
                     logger->trace("🚧 TODO: Route client message to modules");
@@ -451,8 +457,8 @@ void DebugEngine::processCoordinatorMessages() {
         for (int i = 0; i < messagesToProcess; ++i) {
             try {
                 auto message = coordinatorSocket->pullMessage();
-                logger->debug("📩 Coordinator message: topic='{}', data size={}",
+                logger->debug("📩 Coordinator message: topic='{}', data present={}",
-                            message.topic, message.data.dump().size());
+                            message.topic, message.data != nullptr);
 
                 // TODO: Handle coordinator commands (shutdown, config reload, etc.)
                 logger->trace("🚧 TODO: Handle coordinator commands");