Suriyakumarvijayanayagam
4ac08e5a85
Seen on the demo PC: Start did nothing and Stop stayed grey. The supervisor's engine had failed because a second engine already held port 8010, and the tray reported that as nothing at all. The supervisor now keeps the engine's last lines and turns the known ones into a sentence - 'port 8010 is already in use - another Behavision or its engine is still running', 'run behavision-setup again' - which the tray and the window show. Tray clicks no longer run on the menu loop, so a stop that waits for the process cannot make the menu look dead. Two ways that second process came to exist are closed: setup refuses to run while Behavision.exe or the agent is up, and the app watches agent.json so a claim made underneath it - which rotates the API token - is picked up instead of leaving camera sync refused until a restart. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01KGcjxF1cNLcuwc3DAPcnfj
Behavision agent (Go)
The half of the edge install that touches the network. The Python engine keeps the cameras and the models; this keeps the tray icon, the UI shell, the MQTT connection and the offline queue.
┌─ agent (Go) ───────────────────┐ ┌─ engine (Python) ────────┐
│ tray icon + WebView2 window │ │ RTSP capture │
│ supervises the engine process │───────▶│ YuNet / ArcFace / FAISS │
│ MQTT publish + offline spool │◀───────│ SQLite (biometric) │
│ S3 handoff, tenant config │ local │ localhost API + events │
└────────────────────────────────┘ HTTP └──────────────────────────┘
Why the split
Go cannot run ONNX, OpenCV or FAISS, so the engine stays Python and ships frozen. Go is here for what it is actually better at: a durable queue that survives a store's internet dropping, a supervised child process, and one language shared with the server so the MQTT contract has a single definition.
Why not a Windows service
A service runs in session 0 and cannot draw a tray icon — that is Windows session isolation, not a library limitation. Since the product is "user starts and stops it from the tray", the agent is a normal user-session process that spawns the engine as a child. That also means it never needs elevation at runtime: starting a child process does not, controlling a service does.
internal/engine is written so a service wrapper can be added later without
touching the supervision logic.
Layout
main.go entry point, mode dispatch
internal/engine start/stop/supervise the Python engine, health polling
internal/spool durable event queue (survives restart and outage)
internal/mqtt broker client, publishes from the spool
internal/config tenant identity, broker settings, credentials
frontend/ React UI served into the WebView
Build
go build ./... # agent alone
wails build # agent + frontend, once the UI is added