POST /api/devices
{ "id": "dev_x", "name": "Living", "module_id": "mod_x" }

POST /api/modules
{ "id": "mod_x", "name": "Temp", "code": "..." }

PUT /api/devices/{id}
{ "module_id": "mod_y" }

POST /api/generate
{ "device_id": "dev_x", "module_id": "mod_x" }