@startuml comm
box ClientProcess #LightBlue
Participant Caller
Participant CloudPointClient
Participant StereoRectifier
Participant PointCloudBuilder
Participant TCPClient
end box
box UnityProcess #LightGreen
Participant TCPServer
Participant CloudPointServer
Participant MainThreadQueue
Participant UnityWorld
end box

== Initialization ==

UnityWorld -> CloudPointServer : Awake() — crpc_init()
activate CloudPointServer
CloudPointServer -> TCPServer : start (await connections)
activate TCPServer

Caller -> CloudPointClient : connect()
activate CloudPointClient
CloudPointClient -> TCPClient : establish TCP connection
TCPClient -> TCPServer : TCP handshake
TCPServer -> TCPServer : spawn per-client handler thread (loops)

CloudPointClient -> TCPClient : get-stereo-calibration
TCPClient -> TCPServer : send request
TCPServer -> CloudPointServer : dispatch
CloudPointServer -> MainThreadQueue : enqueue task
MainThreadQueue -> UnityWorld : Update() dequeues
activate UnityWorld
UnityWorld -> UnityWorld : read camera params
UnityWorld -> MainThreadQueue : tcs.SetResult(calibration JSON)
deactivate UnityWorld
MainThreadQueue -> CloudPointServer : task complete
CloudPointServer -> TCPServer : send response
TCPServer -> TCPClient : response
TCPClient -> CloudPointClient : calibration received
CloudPointClient -> StereoRectifier : init(calibration)\ncv::stereoRectify + remap maps
deactivate CloudPointClient

== Per compute_cloud() call ==

Caller -> CloudPointClient : compute_cloud()
activate CloudPointClient
CloudPointClient -> TCPClient : get-image-pair
TCPClient -> TCPServer : send request
TCPServer -> CloudPointServer : dispatch
CloudPointServer -> MainThreadQueue : enqueue task
MainThreadQueue -> UnityWorld : Update() dequeues
activate UnityWorld
UnityWorld -> UnityWorld : Render() both cameras\nReadPixels + vertical flip\nBase64 encode
UnityWorld -> MainThreadQueue : tcs.SetResult(image pair JSON)
deactivate UnityWorld
MainThreadQueue -> CloudPointServer : task complete
CloudPointServer -> TCPServer : send response
TCPServer -> TCPClient : response (base64 left + right)
TCPClient -> CloudPointClient : image pair received

CloudPointClient -> StereoRectifier : rectify(left, right)
StereoRectifier -> StereoRectifier : cv::remap both images
StereoRectifier -> CloudPointClient : rectified pair

CloudPointClient -> PointCloudBuilder : build(rectified, Q)
PointCloudBuilder -> PointCloudBuilder : cv::StereoSGBM disparity\n(1/16 scale)\ncv::reprojectImageTo3D\nNaN filter
PointCloudBuilder -> CloudPointClient : PointCloud

CloudPointClient -> Caller : std::expected<PointCloud, Error>
deactivate CloudPointClient

== Teardown ==

Caller -> CloudPointClient : destruct
deactivate CloudPointClient
UnityWorld -> CloudPointServer : OnDestroy() — crpc_deinit()
deactivate CloudPointServer
deactivate TCPServer

@enduml