@startuml Seq_RealtimeDataTransfer

title Real-time Data Transfer — End-to-End Scenario

participant "CANDumpPlayer" as CDP
participant "CAN Bus\n(SocketCAN)" as CANBUS
participant "CloudConnect\n(CloudConnectController)" as LRC
participant "CloudConnectServer" as RS
participant "Luis application" as APP
participant "Cloud pipeline\n(planned)" as PIPE

note over CDP
  Replays a candump log onto SocketCAN
  at a configurable speed multiplier.
  See Seq_CANDumpPlayer for detail.
end note

CDP -> CANBUS : writeFrame(can_id, payload)
CANBUS -> LRC : didFrameReceive(QCanBusFrame)

LRC -> LRC : MessageDispatcher reassembles\nmulti-frame Can::Message\n(see Seq_CANToCloud for detail)

alt action == Drop (or msgId not in _msgHandling)
    LRC -> LRC : discard
else action == SendDelta AND payload unchanged\n(cached data.chopped(1) == new data.chopped(1))
    LRC -> LRC : discard (no change)
else action == SendAlways OR SendDelta with new payload
    LRC -> LRC : canMessageToProtobufByteArray()\n→ serialised protobuf bytes

    LRC -> RS : send(topic, seq++, protobuf payload)
    RS -> APP : CloudConnectFrame frame over\n/tmp/cloudconnect.sock

    LRC -->> PIPE : route → spool → publish
end

note over PIPE
  NOT YET IMPLEMENTED.

  The Connectivity Agent process and its UDS have been
  removed. The replacement in-process pipeline is:

    Router      → resolve MQTT topic from Type,
                  build Envelope
    MessageSpool → durable insert BEFORE publish
    MqttPublisher → QoS 1 PUBLISH to AWS IoT Core
                  → PUBACK → MessageSpool::remove()
    SpoolDrain  → replay spooled messages on reconnect

  Until this lands, nothing is sent to the cloud.
  See docs/SDD/AgentMigrationPlan.md Phases 2-3.
end note

@enduml