@startuml Seq_RealtimeDataTransfer

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

participant "CANDumpPlayer" as CDP
participant "CAN Bus\n(SocketCAN)" as CANBUS
participant "LeahiRt\n(LeahiRtController)" as LRC
participant "Unix Domain\nSocket" as UDS
participant "AgentSim\n(AgentSimController)" as ASC

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 == send_delta AND payload unchanged\n(cached data.chopped(1) == new data.chopped(1))
    LRC -> LRC : discard (no change)
else action == send_always OR send_delta with new payload
    LRC -> LRC : canMessageToProtobufByteArray()\n→ serialised protobuf bytes
    LRC -> UDS : AgentMessage frame\n(msgId=topic, seq++, protobuf payload)
    UDS -> ASC : readyRead
    ASC -> ASC : AgentMessage::feed() → Complete\nlogMessage() + Envelope parse\n(see Seq_AgentSim for detail)
end

@enduml