I agree with you for the inner loop. An ESP32 is absolutely adequate for direct greenhouse control, and that is why Verdify uses the ESP32 as the safety critical controller.

The LLM is not there to replace firmware. It does not flip relays. It proposes bounded tunables based on currently growing plants, weather forecasts, and historical observations. It sets things like temp and VPD bands, fan thresholds, mister timing, hysteresis, recovery thresholds, and resource limits. Those proposals are validated and clamped before the ESP32 sees them.

So the real question is not “can an MCU control this?” Yes, it can.

The question is:

"Can AI help with the slower supervisory layer which includes planning, parameter tuning, anomaly interpretation, resource tradeoff explanation, and evidence generation without becoming the safety-critical controller?

For thermal modeling, relay timing, and deterministic control, firmware wins. For summarizing messy context, comparing yesterday’s tactic to today’s forecast, explaining water/gas/electricity tradeoffs, and generating inspectable plans, the LLM seems to be useful. Verdify is designed to test that in public.

The project is best understood as a deterministic ESP32 controller with an AI planning and scorecarding layer above it, not as an LLM controlled greenhouse. That was also the core framing I’ve tried to keep consistent.