Index: tools/AgentSim/AgentSimController.cpp
===================================================================
diff -u -rb1bab9e8d105f31bca82799af43ed354a4ab2df0 -r402926738e7394ee2d3dc7add2e6d755f06a289d
--- tools/AgentSim/AgentSimController.cpp	(.../AgentSimController.cpp)	(revision b1bab9e8d105f31bca82799af43ed354a4ab2df0)
+++ tools/AgentSim/AgentSimController.cpp	(.../AgentSimController.cpp)	(revision 402926738e7394ee2d3dc7add2e6d755f06a289d)
@@ -11,7 +11,12 @@
  *
  */
 #include "AgentSimController.h"
+#include "LeahiMsgProtoUtils.h"
 
+#include <google/protobuf/descriptor.h>
+#include <google/protobuf/dynamic_message.h>
+#include <google/protobuf/util/json_util.h>
+
 #include <QDebug>
 
 /*!
@@ -91,8 +96,7 @@
         result = _rxMsg.feed(_rxBuf);
         switch (result) {
             case AgentMessage::FeedResult::Complete:
-                logMessage(_rxMsg.msgId(), _rxMsg.sequence(), _rxMsg.payload());
-                sendAck(_rxMsg.sequence());
+                handleMessage(_rxMsg);
                 _rxMsg.reset();
                 break;
             case AgentMessage::FeedResult::HeaderError:
@@ -108,6 +112,61 @@
 }
 
 /*!
+ * \brief   AgentSimController::handleMessage
+ * \details Decodes a received frame and prints its typed body as JSON, generically
+ *          via the protobuf descriptor pool (msgId -> message name -> dynamic parse).
+ * \param   msg  The complete AgentMessage frame.
+ */
+void AgentSimController::handleMessage(const AgentMessage &msg)
+{
+    const QByteArray payload = msg.payload();
+    logMessage(msg.msgId(), msg.sequence(), payload);
+
+    // Read the Header (field 1, shared by every typed message) to learn the msgId.
+    leahi::messages::Envelope envelope;
+    if (!envelope.ParseFromArray(payload.constData(), payload.size())) {
+        qWarning().noquote() << "AgentSim: could not parse Envelope header — frame dropped";
+        return;
+    }
+    const leahi::messages::Header &header = envelope.header();
+
+    // Identify the concrete message type from the msgId and decode it generically.
+    const std::string &typeName = leahi::msgIdToProtoName(static_cast<quint16>(header.msgid()));
+    if (typeName.empty()) {
+        qWarning().noquote() << QString("AgentSim: unknown msgId=0x%1 — cannot decode typed body")
+            .arg(header.msgid(), 4, 16, QChar('0'));
+        return;
+    }
+
+    const google::protobuf::Descriptor *desc =
+        google::protobuf::DescriptorPool::generated_pool()->FindMessageTypeByName(typeName);
+    if (desc == nullptr) {
+        qWarning().noquote() << "AgentSim: no descriptor for" << QString::fromStdString(typeName);
+        return;
+    }
+
+    google::protobuf::DynamicMessageFactory factory;
+    std::unique_ptr<google::protobuf::Message> body(factory.GetPrototype(desc)->New());
+    if (!body->ParseFromArray(payload.constData(), payload.size())) {
+        qWarning().noquote() << "AgentSim: could not parse" << QString::fromStdString(typeName);
+        return;
+    }
+
+    std::string json;
+    google::protobuf::util::JsonPrintOptions opts;
+    opts.add_whitespace = true;
+    opts.always_print_primitive_fields = true;
+    google::protobuf::util::MessageToJsonString(*body, &json, opts);
+
+    // protobuf renders msgId as a decimal integer; rewrite it as 0x + 4-digit hex.
+    QString jsonStr = QString::fromStdString(json);
+    jsonStr.replace(QString("\"msgId\": %1").arg(header.msgid()),
+                    QString("\"msgId\": \"0x%1\"").arg(header.msgid(), 4, 16, QChar('0')));
+    qDebug().noquote() << QString::fromStdString(typeName) << ":" << Qt::endl
+                       << jsonStr;
+}
+
+/*!
  * \brief   AgentSimController::logMessage
  * \details Logs the message identifier, sequence number, and payload length.
  * \param   msgId     Message identifier from the parsed frame.
@@ -121,19 +180,3 @@
                              .arg(sequence)
                              .arg(payload.size());
 }
-
-/*!
- * \brief   AgentSimController::sendAck
- * \details Builds an Ack frame carrying \p sequence and writes it to the client socket.
- * \param   sequence  Sequence number to echo back in the Ack frame.
- */
-void AgentSimController::sendAck(quint16 sequence)
-{
-    if (!_client || _client->state() != QLocalSocket::ConnectedState) {
-        return;
-    }
-    const QByteArray frame = AgentMessage::build(AgentMessage::MsgId::Ack, sequence);
-    _client->write(frame);
-    _client->flush();
-    qInfo().noquote() << QString("AgentSim: tx  MsgId=Ack  seq=%1").arg(sequence);
-}