The Next.js UI is deployed on Vercel. This Space is not the product frontend.
Backend + O1–O20 agents: huggingface.co/subhan07/hvac-agents
To run the API on Hugging Face you need a Docker Space (PRO). Until then run uvicorn backend.main:app --port 8000 locally and point Vercel HVAC_API_ORIGIN at that host.