Architecture¶

Greenhouse Sentinel separates measurement, evaluation, presentation, and response guidance so each part can be tested and explained independently.

System Boundary¶

The hub receives local sensor readings and produces a recommendation. It does not operate pumps, vents, heaters, locks, or other physical equipment. A person remains responsible for any physical action.

Sensors -> sample normalizer -> rule engine -> local event store -> dashboard
                                  |
                                  +-> response guidance

Components¶

Sample normalizer: converts each supported sensor value to a consistent unit and marks stale data.
Rule engine: evaluates the most recent valid samples against versioned thresholds.
Event store: retains 30 days of readings, state changes, and acknowledgements on the hub.
Dashboard: presents current conditions, recent trends, and the reason for the current state.

Decision States¶

The engine assigns one of three states after three consecutive samples meet the same condition.

State	Example condition	Operator expectation
Normal	All readings are inside target ranges	Continue scheduled checks
Watch	One reading is near a threshold	Inspect within 30 minutes
Act	One reading exceeds a threshold	Follow the displayed response

Feature in action: portable table

This is a semantic Markdown table because the content has repeated, comparable fields. Zensical renders it responsively. The export script maps it to a real Word table with a header row. Ordinary explanatory prose remains outside tables for readability and accessibility.

The three-sample rule reduces noise without hiding sustained change. Thresholds in this demo are illustrative, not horticultural advice.

Data Retention¶

The hub stores 30 days of samples and event history. An export contains timestamps, normalized readings, state transitions, acknowledgements, and the rule-set version. It does not contain names unless an operator voluntarily enters one in a note.

Failure Behavior¶

If one sensor becomes stale, the dashboard reports sensor unavailable and does not infer a replacement value. The last valid measurement remains visible with its timestamp. See Troubleshooting.