# machineGroupControl

> **Reflects code as of `afc304b` · regenerated `2026-05-11` via `npm run wiki:all`**
> If this banner is stale, the page may be out of date. Treat as informative, not authoritative.

## 1. What this node is

**machineGroupControl (MGC)** is an S88 Unit orchestrator that coordinates multiple `rotatingMachine` children sharing a common header. It receives a demand setpoint, evaluates valid pump combinations against the group's totals and curves, picks the best operating point (BEP-Gravitation or NCog), and dispatches per-machine flow setpoints + start/stop commands.

## 2. Position in the platform

```mermaid
flowchart LR
    parent[pumpingStation<br/>Process Cell]:::pc -->|set.demand| mgc[machineGroupControl<br/>Unit]:::unit
    header[measurement<br/>header pressure]:::ctrl -.data.-> mgc
    mgc -->|flowmovement / execsequence| m_a[rotatingMachine A]:::equip
    mgc -->|flowmovement / execsequence| m_b[rotatingMachine B]:::equip
    mgc -->|flowmovement / execsequence| m_c[rotatingMachine C]:::equip
    mgc -->|child.register| parent
    m_a -->|child.register| mgc
    m_b -->|child.register| mgc
    m_c -->|child.register| mgc
    classDef pc fill:#0c99d9,color:#fff
    classDef unit fill:#50a8d9,color:#000
    classDef equip fill:#86bbdd,color:#000
    classDef ctrl fill:#a9daee,color:#000
```

S88 colours: Process Cell `#0c99d9`, Unit `#50a8d9`, Equipment `#86bbdd`, Control Module `#a9daee`. Source of truth: `.claude/rules/node-red-flow-layout.md`.

## 3. Capability matrix

| Capability | Status | Notes |
|---|---|---|
| Aggregate group flow / power totals | ✅ | `TotalsCalculator` — absolute and dynamic. |
| Valid-combination enumeration | ✅ | `combinatorics/pumpCombinations`. |
| Best-combination optimiser (BEP-Gravitation) | ✅ | Directional or symmetric variant. |
| Best-combination optimiser (NCog) | ✅ | Normalised cost-of-goods score. |
| Priority / equal-flow control | ✅ | `mode='prioritycontrol'`. |
| Priority percentage control | ✅ | Requires `scaling='normalized'`. |
| Optimal control | ✅ | `mode='optimalcontrol'`. |
| Group efficiency + BEP distance | ✅ | `GroupEfficiency`. |
| Header-pressure equalisation | ✅ | `operatingPoint.equalize()`. |
| Demand serialisation (latest-wins) | ✅ | Inline gate; deferred call drains on completion. |
| Forced shutdown on `Qd ≤ 0` | ✅ | `turnOffAllMachines()`. |

## 4. Code map

```mermaid
flowchart TB
    subgraph nodeRED["nodeClass.js — adapter (BaseNodeAdapter)"]
        nc["buildDomainConfig()<br/>static DomainClass, commands"]
    end
    subgraph domain["specificClass.js — orchestrator (BaseDomain)"]
        sc["MachineGroup.configure()<br/>ChildRouter rules<br/>handleInput() dispatch gate"]
    end
    subgraph concerns["src/ concern modules"]
        groupOps["groupOps/<br/>GroupOperatingPoint + curves"]
        totals["totals/<br/>TotalsCalculator"]
        combi["combinatorics/<br/>validPumpCombinations"]
        opt["optimizer/<br/>BEP-Grav / NCog selectors"]
        efficiency["efficiency/<br/>GroupEfficiency + BEP dist"]
        dispatch["control/<br/>strategies (equalFlow / prioPct)"]
        io["io/<br/>output + status"]
        commands["commands/<br/>topic registry + handlers"]
    end
    nc --> sc
    sc --> groupOps
    sc --> totals
    sc --> combi
    sc --> opt
    sc --> efficiency
    sc --> dispatch
    sc --> io
    nc --> commands
```

| Module | Owns | Read first if you're changing… |
|---|---|---|
| `groupOps/` | Group operating point + child read helpers | Header pressure handling, child measurement plumbing. |
| `totals/` | Absolute + dynamic flow/power totals | Demand clamping, totals math. |
| `combinatorics/` | Enumeration of valid pump subsets | Which combinations are considered eligible. |
| `optimizer/` | Best-combination selectors | Optimiser selection method, scoring math. |
| `efficiency/` | Group efficiency, BEP distance | BEP gravitation tuning, peak math. |
| `control/strategies.js` | Per-mode dispatch (priority, prioPct) | Mode behaviour, priorityList usage. |
| `dispatch/` | Demand fan-out helpers (legacy alongside inline gate) | Serialisation, mid-flight overrides. |
| `commands/` | Input-topic registry and handlers | New input topics, payload validation. |
| `io/` | `getOutput`, `getStatusBadge` | Output shape, dashboard badge. |

## 5. Topic contract

> **Auto-generated** from `src/commands/index.js`. Do NOT hand-edit between the markers. Re-run `npm run wiki:contract`.

<!-- BEGIN AUTOGEN: topic-contract -->

| Canonical topic | Aliases | Payload | Unit | Effect |
|---|---|---|---|---|
| `set.mode` | `setMode` | `string` | — | Switch the machine group between auto / manual modes. |
| `set.scaling` | `setScaling` | `string` | — | Select the group scaling strategy. |
| `child.register` | `registerChild` | `string` | — | Register a child machine with this group. |
| `set.demand` | `Qd` | `any` | `volumeFlowRate` (default `m3/h`) | Operator demand setpoint dispatched to the child machines. |

<!-- END AUTOGEN: topic-contract -->

## 6. Child registration

`ChildRouter` declarations in `specificClass.js → configure()`.

```mermaid
flowchart LR
    subgraph kids["accepted children (softwareType)"]
        mach["machine<br/>(rotatingMachine)"]:::equip
        m["measurement<br/>(header pressure)"]:::ctrl
    end
    mach -->|"pressure.measured.downstream<br/>pressure.measured.differential<br/>flow.predicted.downstream"| eq[operatingPoint.equalize<br/>+ totals refresh]
    m -->|"&lt;type&gt;.measured.&lt;position&gt;"| mirror[mirror into own<br/>MeasurementContainer]
    mirror -->|"if type === 'pressure'"| eq
    eq --> emit[notifyOutputChanged]
    classDef equip fill:#86bbdd,color:#000
    classDef ctrl fill:#a9daee,color:#000
```

| softwareType | filter / subscribed events | Side-effect |
|---|---|---|
| `machine` | onRegister stores in `this.machines[id]`; subscribes to `pressure.measured.downstream`, `pressure.measured.differential`, `flow.predicted.downstream` | `handlePressureChange()` — equalise + recompute totals + recompute group efficiency. |
| `measurement` | onRegister attaches listener for `<asset.type>.measured.<positionVsParent>` | Mirror value into MGC's own MeasurementContainer; pressure also triggers `handlePressureChange()`. |

## 7. Lifecycle — what one event does

```mermaid
sequenceDiagram
    participant parent as pumpingStation
    participant mgc as MGC
    participant op as GroupOperatingPoint
    participant tot as TotalsCalculator
    participant opt as optimizer
    participant kids as rotatingMachine[]

    parent->>mgc: set.demand (Qd)
    Note over mgc: dispatch gate — latest-wins
    mgc->>mgc: abortActiveMovements('new demand')
    mgc->>tot: calcDynamicTotals()
    mgc->>mgc: clamp Qd to [minFlow, maxFlow]
    alt mode=optimalcontrol
        mgc->>mgc: validPumpCombinations(Qd)
        mgc->>opt: pick best (BEP-Grav | NCog)
        opt-->>mgc: bestCombination + bestFlow/Power
        mgc->>kids: flowmovement (per-pump flow)
        mgc->>kids: execsequence (startup / shutdown)
    else mode=prioritycontrol
        mgc->>mgc: equalFlowControl(Qd, powerCap, priorityList)
    end
    mgc->>op: writeOwn flow/power predicted (AT_EQUIPMENT + DOWNSTREAM)
    mgc->>mgc: notifyOutputChanged()
```

## 8. Data model — `getOutput()`

What lands on Port 0. Composed in `io/output.js → getOutput(this)` and delta-compressed by `outputUtils.formatMsg`.

<!-- BEGIN AUTOGEN: data-model -->

| Key | Type | Unit | Sample |
|---|---|---|---|
| `absDistFromPeak` | number | — | `0` |
| `mode` | string | — | `"optimalcontrol"` |
| `relDistFromPeak` | number | — | `0` |
| `scaling` | string | — | `"normalized"` |

<!-- END AUTOGEN: data-model -->

**Concrete sample** (excerpt — see live test output for the canonical shape):

~~~json
{
  "mode": "optimalcontrol",
  "scaling": "normalized",
  "flow.predicted.atequipment.<nodeId>": 0.0125,
  "flow.predicted.downstream.<nodeId>":  0.0125,
  "power.predicted.atequipment.<nodeId>": 1800,
  "efficiency.predicted.atequipment.<nodeId>": 0.65,
  "absDistFromPeak": 0.02,
  "relDistFromPeak": 0.10
}
~~~

The `<nodeId>` segment is the Node-RED node id assigned at deploy time.

## 9. Configuration — editor form ↔ config keys

```mermaid
flowchart TB
    subgraph editor["Node-RED editor form"]
        f1[Control mode dropdown]
        f2[Scaling dropdown]
        f3[Optimisation method]
        f4[Output unit (flow)]
        f5[Position vs parent]
        f6[Allowed sources / actions per mode]
    end
    subgraph cfg["Domain config slice"]
        c1[mode.current]
        c2[scaling.current]
        c3[optimization.method]
        c4[general.unit]
        c5[functionality.positionVsParent]
        c6[mode.allowedSources<br/>mode.allowedActions]
    end
    f1 --> c1
    f2 --> c2
    f3 --> c3
    f4 --> c4
    f5 --> c5
    f6 --> c6
```

| Form field | Config key | Default | Range | Where used |
|---|---|---|---|---|
| Control mode | `mode.current` | `optimalControl` | enum (`prioritycontrol`, `prioritypercentagecontrol`, `optimalcontrol`) | dispatch switch in `_runDispatch` |
| Scaling | `scaling.current` | `normalized` | enum (`absolute`, `normalized`) | demand mapping in `_runDispatch` |
| Optimisation method | `optimization.method` | `BEP-Gravitation-Directional` | enum (`NCog`, `BEP-Gravitation`, `BEP-Gravitation-Directional`) | `_optimalControl` selector |
| Output unit (flow) | `general.unit` | `m3/h` | unit string | unit policy `output.flow` |
| Position vs parent | `functionality.positionVsParent` | `atEquipment` | enum | event suffix for parent subscription |

## 10. State chart

MGC is **event-driven and stateless** with respect to operating modes — there is no FSM. The closest thing to "state" is the dispatch gate. Diagram for that single state vector:

```mermaid
stateDiagram-v2
    [*] --> idle_disp: configure()
    idle_disp --> dispatching: handleInput(Qd)
    dispatching --> idle_disp: dispatch complete
    dispatching --> dispatching: handleInput(Qd) — deferred and re-fired on completion
    dispatching --> turning_off: Qd <= 0
    turning_off --> idle_disp: all machines acknowledged shutdown
```

While `dispatching`, additional `handleInput` calls overwrite `_delayedCall` (latest-wins); the gate drains the latest one on completion. `turnOffAllMachines()` clears `_delayedCall` to make turn-off the final intent.

## 11. Examples

| Tier | File | What it shows | Status |
|---|---|---|---|
| Basic | `examples/basic.flow.json` | Single MGC + 2 pumps, manual setDemand | ⚠️ legacy shape, pre-refactor |
| Integration | `examples/integration.flow.json` | MGC wired under pumpingStation | ⚠️ legacy shape, pre-refactor |
| Edge | `examples/edge.flow.json` | Mid-flight demand override + abort | ⚠️ legacy shape, pre-refactor |

Tier 1/2/3 visual-first example flows are still TODO (see `MEMORY.md` "TODO: Example Flows"). Screenshots will land under `wiki/_partial-screenshots/machineGroupControl/` when the new flows ship.

## 12. Debug recipes

| Symptom | First thing to check | Where to look |
|---|---|---|
| No combination selected | Demand outside `[dynamicTotals.flow.min, max]` — clamped on entry; `_optimalControl` returns early if combinations empty. | `validPumpCombinations` + warn log. |
| Group flow stuck at zero | Machines never reach an `ACTIVE_STATE` — check per-pump startup logs. | `isMachineActive`. |
| Priority-percentage mode warns and exits | Mode requires `scaling='normalized'`. Set both. | `_runDispatch` switch. |
| Stale flow setpoints on chained calls | Dispatch gate may have collapsed multiple calls — confirm `_delayedCall` was honoured. | `handleInput` finally block. |
| Header pressure not equalising | Pressure children must register with `asset.type='pressure'` and a matching position. | `operatingPoint.equalize`. |
| Optimiser picks unexpected combo | Verify `optimization.method` and per-method scoring (NCog vs BEP-Grav). | `optimizer/`. |

> Never ship `enableLog: 'debug'` in a demo — fills the container log within seconds and obscures real errors.

## 13. When you would NOT use this node

- Don't use MGC for a **single pump** — wire `rotatingMachine` directly. MGC's combinatorics + totals add no value below N=2.
- Don't use MGC for **valves** — use `valveGroupControl`. MGC's optimiser assumes a flow-vs-pressure characteristic curve.
- Don't use MGC when the pumps live behind **independent headers** — combinations assume a shared discharge / suction pressure.

## 14. Known limitations / current issues

| # | Issue | Tracked in |
|---|---|---|
| 1 | `optimalControl` requires every machine to expose a curve — null-curve members silently exclude themselves from combinations. | `combinatorics/pumpCombinations`. |
| 2 | Mid-flight setpoint overrides on `accelerating` / `decelerating` rely on `abortActiveMovements` per dispatch — a sequence with no awaitable `abortMovement` will warn but proceed. | `abortActiveMovements`. |
| 3 | Power-cap parameter exposed but not surfaced as a topic input — only programmatic via `handleInput(source, demand, powerCap)`. | `commands/index.js` — no canonical topic. |
| 4 | Tier 1/2/3 visual-first example flows not yet written. | P9 follow-up. |