Index: docs/SDD/Class_Overview.puml
===================================================================
diff -u -rf9eefe0a6092719f35d5a73fa43632c8c779e0df -r8b98ff34313ee5d3f5d49672d622162acfc755c9
--- docs/SDD/Class_Overview.puml	(.../Class_Overview.puml)	(revision f9eefe0a6092719f35d5a73fa43632c8c779e0df)
+++ docs/SDD/Class_Overview.puml	(.../Class_Overview.puml)	(revision 8b98ff34313ee5d3f5d49672d622162acfc755c9)
@@ -6,28 +6,47 @@
 skinparam class {
     BackgroundColor<<generated>> LightYellow
     BackgroundColor<<tool>> LightCyan
-    BackgroundColor<<orphaned>> #EEEEEE
-    BorderStyle<<orphaned>> dashed
+    BackgroundColor<<external>> #E8F0E8
 }
 
 package "CloudConnect (process)" {
     class CloudConnectController {
-        -_settings: QSettings
         -_canInterface: Can::CanInterface
-        -_canThread: QThread
         -_dispatcher: Can::MessageDispatcher
-        -_msgHandling: QHash<Can::MsgId, MsgHandling>
-        -_msgCache: QMap<Can::MsgId, pair<bool, Can::Message>>
-        -_appServer: CloudConnectServer
-        -_txSequence: quint16
+        -_canCache: QMap<Can::MsgId, pair<bool, Can::Message>>
+        -_canRouting: QHash<Can::MsgId, CanRouting>
+        -_appServerSocketPath: QString
+        -_appServer: QSharedPointer<CloudConnectServer>
+        -_mqttClient: MqttClient
+        -_topicPrefix: QString
+        -_deviceId: QString
         __
-        +CloudConnectController(configPath, msgHandlingPath)
+        +CloudConnectController(parent)
+        +loadConfig(configPath): bool
+        +initThread(QThread&)
+        +startCan(): bool
         +listenForApp(): bool
-        -loadMsgHandling(msgHandlingPath)
+        +connectToCloud(): bool
+        -loadCanRouting(canRoutingPath): bool
+        -mqttTopic(Topic): QString
         __
-        -onFrameReceive(QCanBusFrame)
-        -onMessageReceive(Can::Message)
+        -onCanFrameReceive(QCanBusFrame) <<slot>>
+        -onCanMessageReceive(Can::Message) <<slot>>
+        -onCloudStateChanged(ClientState) <<slot>>
+        -onCloudMessageStatusChanged(id, status, props) <<slot>>
+        -onCloudMessageReceived(QByteArray, QMqttTopicName) <<slot>>
     }
+
+    enum "CloudConnectController::CanAction" as CanAction {
+        Drop
+        SendAlways
+        SendDelta
+    }
+
+    class "CloudConnectController::CanRouting" as CanRouting {
+        +action: CanAction = Drop
+        +topic: CloudConnectFrame::Topic = NormalPriority
+    }
 }
 
 package "Comms (lib)" {
@@ -37,7 +56,7 @@
         -_txFrameCount: FrameCount
         -_erFrameCount: FrameCount
         __
-        +init(thread: QThread&): bool
+        +init(): bool
         +quitDevice()
         +enableConsoleOut(bool)
         +status(): QString
@@ -53,18 +72,47 @@
         -onFrameWritten(qint64) <<slot>>
     }
 
-    class CloudConnectClient <<orphaned>> {
+    class MqttClient {
+        -_client: QMqttClient*
+        -_config: Config
+        -_sslConfig: QSslConfiguration
+        __
+        +init(Config): bool
+        +open(): bool
+        +close()
+        +publish(topic, payload, msgId&, qos = 1): bool
+        +subscribe(topicFilter, qos = 1): bool
+        __
+        +didStateChanged(ClientState) <<signal>>
+        +didMessageStatusChanged(id, status, props) <<signal>>
+        +didMessageReceived(QByteArray, QMqttTopicName) <<signal>>
+        __
+        -onStateChanged() <<slot>>
+    }
+
+    class "MqttClient::Config" as MqttConfig {
+        +endpoint: QString
+        +port: quint16 = 8883
+        +certPath: QString
+        +keyPath: QString
+        +caPath: QString
+        +clientId: QString
+        +keepAliveSecs: quint16 = 30
+        +cleanSession: bool = true
+    }
+
+    class CloudConnectClient {
         -_socket: QLocalSocket
         -_reconnectTimer: QTimer
         -_socketPath: QString
         -_rxBuf: QByteArray
         -_rxMsg: CloudConnectFrame
         __
         +init(socketPath, reconnectIntervalMs, thread): bool
-        +send(type, sequence, payload): bool
+        +send(topic, sequence, payload): bool
         +quit() <<slot>>
         __
-        +didMessageReceive(Type, seq, payload) <<signal>>
+        +didMessageReceive(Topic, seq, payload) <<signal>>
         +didConnect() <<signal>>
         +didDisconnect() <<signal>>
         __
@@ -75,24 +123,17 @@
         -onReconnectTimer() <<slot>>
     }
 
-    note bottom of CloudConnectClient
-      No call sites. The agent socket it served
-      was removed in Phase 1; the class and its
-      build entries in Comms remain. Delete or
-      repurpose — see AgentMigrationPlan.md §7.
-    end note
-
     class CloudConnectServer {
         -_server: QLocalServer
         -_client: QLocalSocket*
         -_rxBuf: QByteArray
         -_rxMsg: CloudConnectFrame
         __
         +listen(socketPath): bool
-        +send(type, sequence, payload): bool
+        +send(topic, sequence, payload): bool
         +isConnected(): bool
         __
-        +didMessageReceive(Type, seq, payload) <<signal>>
+        +didMessageReceive(Topic, seq, payload) <<signal>>
         +didConnect() <<signal>>
         +didDisconnect() <<signal>>
         __
@@ -122,20 +163,20 @@
 
     class CloudConnectFrame {
         -_headerBuf: QByteArray
-        -_rxType: Type
+        -_rxTopic: Topic
         -_rxSequence: quint16
         -_rxPayloadLen: quint32
         -_rxPayload: QByteArray
         __
-        +{static} build(type, sequence, payload): QByteArray
+        +{static} build(topic, sequence, payload): QByteArray
         +read(bytes: QByteArray&): ReadState
-        +type(): Type
+        +topic(): Topic
         +sequence(): quint16
         +payload(): QByteArray
         +reset()
     }
 
-    enum "CloudConnectFrame::Type" as Type {
+    enum "CloudConnectFrame::Topic" as Topic {
         HighPriority      = 0x0001
         NormalPriority    = 0x0002
         DeviceLogFile     = 0x0003
@@ -151,33 +192,72 @@
     }
 }
 
-package "CANDumpPlayer (process)" {
+package "MsgUtils (lib)" {
+    class "leahi (generated)" as MsgDefs <<generated>> {
+        +{static} msgIdString(MsgId): QString
+        +{static} msgIdToProtoName(msgId): std::string
+        +{static} canMessageToProtobufByteArray(when, msg, out): bool
+        __
+        Generated from LeahiUnhandled.conf —
+        see CodeGenPipeline
+    }
+
+    class "leahi::messages (protobuf)" as Proto <<generated>> {
+        Envelope
+        Header
+        <474 message types>
+    }
+}
+
+package "Tools (processes)" {
     class "CANDumpPlayer\n(main)" <<tool>> {
         +can_interface: string
         +candump_file: string
         +--speed: double
         +--test: bool
         __
-        Parses candump log and replays\nframes onto SocketCAN at a\nconfigurable speed multiplier
+        Replays a candump log onto\nSocketCAN at a configurable\nspeed multiplier
     }
+
+    class "DCSsim\n(DCSSimController)" <<tool>> {
+        -_server: SslTcpServer
+        __
+        Local MQTT broker simulator.\nTLS/mTLS via SslTcpServer,\nhand-rolled MqttPacket codec.\nStands in for AWS IoT Core.
+    }
 }
 
+package "luis (process)" {
+    class "luis application" as LUIS <<external>> {
+        -_ccClient: CloudConnectClient
+    }
+}
+
 ' --- composition ---
 CloudConnectController *-- CanInterface
-CloudConnectController *-- CloudConnectServer
 CloudConnectController *-- MessageDispatcher
+CloudConnectController *-- MqttClient
+CloudConnectController o-- CloudConnectServer
 
+' --- nested types ---
+CloudConnectController +-- CanAction
+CloudConnectController +-- CanRouting
+MqttClient +-- MqttConfig
+CloudConnectFrame +-- Topic
+CloudConnectFrame +-- ReadState
+
 ' --- internal composition ---
 MessageDispatcher *-- MessageBuilder
 
+' --- external client ---
+LUIS *-- CloudConnectClient
+CloudConnectClient --> CloudConnectServer : connects via LocalSocket\n(CloudConnectFrame stream)
+
 ' --- usage ---
+CloudConnectController ..> MsgDefs : serialize / decode
+MsgDefs ..> Proto : builds
+CanRouting ..> Topic : uses
 CloudConnectServer ..> CloudConnectFrame : uses
-CloudConnectClient ..> CloudConnectFrame : uses
 
-' --- enum nesting ---
-CloudConnectFrame +-- Type
-CloudConnectFrame +-- ReadState
-
 ' --- layout hints ---
 CanInterface -[hidden]- CloudConnectClient