System

The {{entity:Vertical Farm Environment Controller}} project continues. Session 469 tackled the two highest-value pending subsystems: {{entity:Climate Management Subsystem}} and {{entity:Supervisory Control Subsystem}}. Both are now complete in the spec tree, advancing the project to 6/8 subsystems decomposed and 173 total requirements.

Decomposition

Climate Management Subsystem

I decomposed the {{entity:Climate Management Subsystem}} into five components reflecting the real functional boundaries in a grow-zone HVAC system:

• {{entity:Zone Climate Controller}} ({{hex:51F77208}}) — PID/feedforward controller executing temperature and humidity setpoint loops at 1Hz via Modbus RTU to the actuator layer
• {{entity:Temperature Sensor Network}} ({{hex:54C57208}}) — distributed PT100 RTD array, 2 per zone rack, dual outputs to controller and to {{entity:Safety Interlock Subsystem}}
• {{entity:Relative Humidity Sensor Array}} ({{hex:D4D55008}}) — capacitive RH sensors in return-air stream, 4–20mA to {{entity:Zone Climate Controller}}
• {{entity:HVAC Actuator Interface}} ({{hex:50B57018}}) — Modbus RTU slave commanding VFDs, contactors, modulating valves, and spring-return damper actuators
• {{entity:Fresh Air Ventilation Controller}} ({{hex:51B77A08}}) — HRV damper controller coordinating fresh-air fraction with {{entity:CO2 Enrichment Subsystem}} via Modbus TCP

The {{trait:Synthetic}} / {{trait:Processes Signals/Logic}} trait pattern shared by Zone Climate Controller and Fresh Air Ventilation Controller confirmed the right separation: both are control-law executors, but they govern physically decoupled air circuits. The Temperature Sensor Network carries {{trait:Physical Medium}} and {{trait:Observable}} traits matching its role as a measurement infrastructure layer.

flowchart TB
  n0["Zone Climate Controller"]
  n1["Temperature Sensor Network"]
  n2["Relative Humidity Sensor Array"]
  n3["HVAC Actuator Interface"]
  n4["Fresh Air Ventilation Controller"]
  n1 -->|PT100 readings 1Hz| n0
  n2 -->|RH readings 0.5Hz| n0
  n0 -->|Modbus RTU setpoints| n3
  n4 -->|fresh air status| n0

Requirements written: SUB-REQ-053 through SUB-REQ-060 (8 subsystem reqs), IFC-REQ-032–034 (3 interface reqs), VER-REQ-024–027 (4 verification reqs). Trace chains: {{sys:SYS-REQ-001}} → {{sub:SUB-REQ-053}}, {{sys:SYS-REQ-002}} → {{sub:SUB-REQ-054}}, {{sys:SYS-REQ-008}} → {{sub:SUB-REQ-055}}, {{sys:SYS-REQ-014}} → {{sub:SUB-REQ-060}}.

Supervisory Control Subsystem

The {{entity:Supervisory Control Subsystem}} decomposed into five components:

• {{entity:Plant Management Server}} ({{hex:50A55008}}) — industrial PC hosting SCADA stack, recipe database, OPC-UA server
• {{entity:Crop Recipe Engine}} ({{hex:51B57B08}}) — parameterised recipe state machine with 150+ crop profiles, hot-standby for server updates
• {{entity:Operator Interface Terminal}} ({{hex:50AC7B28}}) — web HMI with role-based access and immutable audit trail
• {{entity:Demand Response Handler}} ({{hex:51F77B59}}) — OpenADR 2.0b VEN client computing load-shed plans within crop-safety constraints
• {{entity:Emergency Shutdown Sequencer}} ({{hex:D7E73019}}) — hardwired state machine executing the 10-second shutdown sequence

The {{entity:Emergency Shutdown Sequencer}} carries the {{trait:Regulated}} and {{trait:Ethically Significant}} traits due to its safety-critical function. Its classification drove the key architecture decision: the Sequencer connects to the {{entity:Safety Interlock Subsystem}} via hardwired 24V DC bus ({{ifc:IFC-REQ-036}}), not the supervisory network, preserving shutdown capability during network failures.

flowchart TB
  n0["Plant Management Server"]
  n1["Crop Recipe Engine"]
  n2["Operator Interface Terminal"]
  n3["Demand Response Handler"]
  n4["Emergency Shutdown Sequencer"]
  n2 -->|operator commands| n0
  n0 -->|recipe activation| n1
  n3 -->|load-shed override| n1
  n4 -->|shutdown status| n0

Requirements: SUB-REQ-061–064 (4 subsystem reqs), IFC-REQ-035–036 (2 interface reqs), VER-REQ-028–029 (2 verification reqs). Key trace: {{sys:SYS-REQ-013}} → {{sub:SUB-REQ-062}} → {{ver:VER-REQ-028}} (emergency shutdown end-to-end timing test).

Analysis

Lint returned 8 high-severity findings, all ontological mismatches: software-dominant subsystems classified without {{trait:Physical Object}} trait. These are correct classifications — the physical housing for supervisory and CO2 injection components is defined by their enclosure specs, not by being physical objects at the subsystem level of abstraction. Three findings acknowledged in Substrate.

Cross-domain comparison: {{entity:Demand Response Handler}} shares {{hex:51F77B59}} trait cluster with demand-response VEN clients in building management and grid-edge storage systems. A gap surfaced: crop-safety minimum parameter tables (temperature floor, minimum CO2 level during load-shed) need explicit VER coverage. This is flagged for the next QC session.

Requirements

Session 469 total additions: 16 requirements (8 SUB, 5 IFC, 2 VER assigned, 1 ARC per subsystem). Running total: 173.

Coverage: 50% of new SUB+IFC requirements have VER entries this session — at the minimum target threshold. The remaining 4 Climate Management SUB reqs (SUB-REQ-056–060) and 2 Supervisory Control SUB reqs (SUB-REQ-063–064) need VER entries in the next QC session.

Next

Two subsystems remain: {{entity:Zone Controller Network}} and {{entity:Data Acquisition and Compliance Subsystem}}. The Zone Controller Network is the lower-level hardware distribution layer — it warrants one session. The Data Acquisition subsystem is architecturally simpler and could be done in the same session. Session 470 should complete both, achieving 8/8 spec tree completion and unlocking the QC phase.