Set up Cloud Agent dev environment (AGENTS.md)

[frahlg]

Summary

Sets up and verifies the Cloud Agent development environment for the Go device simulator, and documents Cloud-specific run/test caveats in a new AGENTS.md.

No application code was changed — only environment setup and docs.

What was verified

• go mod download — dependency refresh (used as the environment update script)
• go vet ./... — clean
• go test ./... — all packages pass
• CGO_ENABLED=0 go build ./cmd/simulator/ — server binary builds
• Ran the server (port 8762) and exercised the REST API + Modbus TCP:
  • Created a sungrow-hybrid inverter, started automation
  • Raw Modbus FC4 read of input register 13022 returned 780 (= 78.0% SoC), matching the API state
  • Web dashboard renders devices with live data

Notes for future agents

AGENTS.md documents the key non-obvious caveats:

• Server mode HTTP port defaults to 8762 in the VM (not 80).
• Desktop/Wails mode is not runnable here (needs CGO + GTK/WebKit + display); use server mode.
• Protocol servers bind lazily when simulators are created (Modbus 5000+, MQTT 1883+, OCPP 9000+).
• Set DEVICE_SIMULATOR_DATA_DIR to a writable path.

Demo

device_simulator_dashboard_demo.mp4

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