Cheap for a reason worth stating: the Windows package is already a SOURCE install - a pure-Python wheel plus a setup tool that builds a venv on the target machine, because PyInstaller cannot cross-compile. macOS needs nothing different. Same wheel, same setup tool, a natively built .app in place of the .exe. No frozen engine, no 200 MB, no second packaging story. behavision-setup already handled both platforms (Scripts vs bin, the tasklist check guarded) and cross-compiled for darwin without a change. The one thing that did not was its advice when Python is missing: it told everyone to tick 'Add python.exe to PATH' on a Windows installer page. Software that does not know which machine it is running on is software somebody stops trusting for the rest of the session. MAC=1 opts in, so the ordinary Windows release is unchanged. 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