> **Reflects code as of `f21e2aa` · regenerated `2026-05-11` (hand-written)**
> No `npm run wiki:all` script exists for this library. The API surface block (section 5) is hand-maintained between the AUTOGEN markers. If the banner is stale, treat this page as informative, not authoritative.
---
## 1. What this library is
**generalFunctions** is the shared infrastructure every EVOLV node depends on. It provides the base classes all nodes extend (`BaseDomain`, `BaseNodeAdapter`), the command dispatch engine, the measurement store, unit-policy system, child-registration machinery, InfluxDB output formatting, and a set of domain utilities (PID, curve interpolation, prediction, statistics, coolprop). Nodes hold zero duplicated scaffolding — they only write the logic that differs.
---
## 2. Position in the platform
```mermaid
flowchart LR
gf["generalFunctions\n(shared library)"]:::lib
rm["rotatingMachine\nEquipment"]:::equip
mgc["machineGroupControl\nUnit"]:::unit
ps["pumpingStation\nProcess Cell"]:::proc
meas["measurement\nControl Module"]:::ctrl
valve["valve\nEquipment"]:::equip
vgc["valveGroupControl\nUnit"]:::unit
reactor["reactor\nUnit"]:::unit
settler["settler\nUnit"]:::unit
monster["monster\nUnit"]:::unit
diffuser["diffuser\nEquipment"]:::equip
dashAPI["dashboardAPI\nutility"]:::util
gf --> rm
gf --> mgc
gf --> ps
gf --> meas
gf --> valve
gf --> vgc
gf --> reactor
gf --> settler
gf --> monster
gf --> diffuser
gf --> dashAPI
classDef lib fill:#222,color:#fff,stroke:#444
classDef proc fill:#0c99d9,color:#fff
classDef unit fill:#50a8d9,color:#000
classDef equip fill:#86bbdd,color:#000
classDef ctrl fill:#a9daee,color:#000
classDef util fill:#dddddd,color:#000
```
Every EVOLV node declares `generalFunctions` as a `dependencies` entry and imports from the package root only (`require('generalFunctions')`). Cross-node coupling happens exclusively through this library's API surface and Node-RED messages — never through direct imports between node packages.
All imports use the package root: `const { X } = require('generalFunctions');`
| Export | Import name | Source file | Contract |
|---|---|---|---|
| `BaseDomain` | `BaseDomain` | `src/domain/BaseDomain.js` | Abstract base class for every `specificClass.js`. Provides `emitter`, `config`, `logger`, `measurements`, `childRegistrationUtils`, `router`. Subclass must declare `static name` (maps to schema JSON) and implement `configure()`. See CONTRACTS.md §3. |
| `BaseNodeAdapter` | `BaseNodeAdapter` | `src/nodered/BaseNodeAdapter.js` | Abstract base for every `nodeClass.js`. Wires config build → domain instantiation → registration delay → output strategy → status loop → input dispatch → close handler. Subclass declares `static DomainClass`, `static commands`, `static tickInterval`, `static statusInterval`, and overrides `buildDomainConfig(uiConfig, nodeId)`. See CONTRACTS.md §2. |
| `CommandRegistry` | `CommandRegistry` | `src/nodered/commandRegistry.js` | Class form of the command registry. Accepts array of descriptors (topic, aliases, payloadSchema, units, description, handler). Dispatches by O(1) lookup, normalises units before handler runs, warns on alias use. |
| `createRegistry` | `createRegistry` | `src/nodered/commandRegistry.js` | Factory: `createRegistry(descriptors, options)` → `CommandRegistry`. Used by `BaseNodeAdapter`; rarely needed directly. |
| `UnitPolicy` | `UnitPolicy` | `src/domain/UnitPolicy.js` | Declare unit sets: `UnitPolicy.declare({ canonical, output, curve?, requireUnitForTypes? })`. Returns policy with dual method/property access (`policy.canonical('flow')` and `policy.canonical.flow`). Methods: `canonical`, `output`, `curve`, `resolve`, `convert`, `containerOptions`, `setLogger`. See CONTRACTS.md §6. |
| `LatestWinsGate` | `LatestWinsGate` | `src/domain/LatestWinsGate.js` | Serialises async dispatches so only the latest value wins. `fire(value)` — non-blocking. `fireAndWait(value)` → `Promise` that resolves with dispatch result or `LatestWinsGate.SUPERSEDED`. `drain()` — await idle. See CONTRACTS.md §8. |
| `outputUtils` | `outputUtils` | `src/helper/outputUtils.js` | Singleton-per-node delta-compression engine. `formatMsg(output, config, format)` returns `msg` only when fields changed, or `undefined`. `format` is `'process'` or `'influxdb'`. Consumers must cache and merge. |
| `configUtils` | `configUtils` | `src/helper/configUtils.js` | `new configUtils(defaultConfig)`. `initConfig(userConfig)` validates and merges user values over defaults via `validationUtils`. |
| `childRegistrationUtils` | `childRegistrationUtils` | `src/helper/childRegistrationUtils.js` | `new childRegistrationUtils(parentDomain)`. `registerChild(child, positionVsParent, distance?)` stores child by softwareType/category with alias normalisation. `getChildrenOfType(softwareType, category?)`, `getChildById(id)`, `getAllChildren()`. Normally used via `ChildRouter` — direct use is for advanced cases. |
| `statusBadge` | `statusBadge` | `src/nodered/statusBadge.js` | Pure-function badge builder. `statusBadge.compose(parts, opts?)` → `{ fill, shape, text }`. `statusBadge.error(msg)`, `statusBadge.idle(label)`. Text clipped to 60 chars. See CONTRACTS.md §7. |
| `StatusUpdater` | `StatusUpdater` | `src/nodered/statusUpdater.js` | `new StatusUpdater({ node, source, intervalMs, logger })`. `start()`, `stop()`. Calls `source.getStatusBadge()` on interval; catches errors and shows a red badge. Owned by `BaseNodeAdapter` — rarely needed directly. |
| `interpolation` | `interpolation` | `src/predict/interpolation.js` | Class for 1-D and 2-D curve interpolation (linear, cubic-spline). Used internally by `predict`. |
| `MenuManager` | `MenuManager` | `src/menu/index.js` | `new MenuManager()`. Manages editor dropdown menus (asset, logger, position, aquon). `registerMenu(type, factory)`. Used in node entry files to power Node-RED editor forms. |
| `menuUtils` / `MenuUtils` | via `menuUtils` in helper | `src/helper/menuUtils.js` | Browser-side editor helper. Toggles, data fetching, URL construction, dropdown population, HTML generation. Served to browser via `endpointUtils`. |
| `coolprop` | `coolprop` | `src/coolprop-node/src/index.js` | CoolProp fluid/gas thermodynamic property lookup. Used by nodes that model heat transfer or gas compression. |
| `loadModel` | `loadModel` | `datasets/assetData/modelData/index.js` | Load a JSON model-data asset by dataset type and asset ID (with LRU cache). Preferred over deprecated `loadCurve`. |
| `loadCurve` | `loadCurve` | `datasets/assetData/curves/index.js` | **Deprecated** — load a pump-curve JSON. Replaced by `loadModel`. |
<!-- END AUTOGEN: api-surface -->
---
## 6. Config schema registry
One JSON file per node in `src/configs/`. `ConfigManager.buildConfig` merges the schema defaults with the Node-RED editor values before the domain sees them.
To add a new node: create `src/configs/<nodeName>.json` extending `baseConfig.json`, declare `static name = '<nodeName>'` in the domain class. `configManager.buildConfig` finds it automatically.
---
## 7. Lifecycle — how a node tick or event reaches the output port
The sequence below uses `rotatingMachine` as the example. Every stateful EVOLV node follows the same path. See the [rotatingMachine wiki](../rotatingMachine/Home.md) for node-specific detail.
```mermaid
sequenceDiagram
participant RED as Node-RED runtime
participant BNA as BaseNodeAdapter
participant CMD as CommandRegistry
participant DOM as Domain (specificClass)
participant CR as ChildRouter
participant MC as MeasurementContainer
participant OU as outputUtils
participant PORT as Port 0 / 1 / 2
RED->>BNA: constructor(uiConfig, RED, node, name)
BNA->>BNA: configManager.buildConfig()
BNA->>DOM: new DomainClass(config)
DOM->>MC: new MeasurementContainer(unitPolicy.containerOptions())
Source of truth: `.claude/rules/general-functions.md`.
| Category | Rule |
|---|---|
| **Safe to add** | New named exports. New optional methods on existing classes. New config keys with defaults in the schema. |
| **Requires decision-gate interview** | Removing or renaming any export. Changing a method signature. Changing the output key format of `MeasurementContainer.getFlattenedOutput()`. Changing the `formatMsg` delta-compression behaviour. |
| **Forbidden without migration** | Breaking the 4-segment key shape (`type.variant.position.childId`). Changing Port 0/1/2 payload envelope. Changing the CONTRACTS.md §1–§9 shapes. |
`generalFunctions` is a git submodule shared by all 12 node repos. A breaking change here requires updating every consumer in a single coordinated commit. Before modifying any module, run `grep -r "require('generalFunctions')" nodes/*/` to identify all call sites.
---
## 9. No editor form — consumers' config forms map to config slices
`generalFunctions` has no Node-RED editor form of its own. The library is never placed directly in a flow.
Consumer nodes expose their own editor forms. Each form field writes into a config key that `configManager.buildConfig` validates against the node's schema (in `src/configs/<nodeName>.json`). The resulting merged config is passed to the domain constructor.
For the form-to-config mapping of a specific node, see section 9 of that node's wiki page.
| Child never registers (no `registerChild` log) | Is the child's `softwareType` in the `SOFTWARE_TYPE_ALIASES` map? | `src/helper/childRegistrationUtils.js` line 1–12 and `src/domain/ChildRouter.js` |
| Port 0 sends nothing after an input | `outputUtils` only emits on changes. Is the field actually different from the last call? | Add a debug tap after `formatMsg`; check `outputUtils._output[format]` state |
| Unit mismatch — handler receives wrong value | Did the command descriptor declare `units: { measure, default }`? Is `msg.unit` set by the sender? | `commandRegistry.js` → `_normaliseUnit()`; check the warn log |
| `query.units` returns empty object | The commands array has no descriptors with a `units` field. | `BaseNodeAdapter._buildImplicitUnitsCommand()` |
| `MeasurementContainer.getFlattenedOutput()` returns unexpected key shape | Key is `type.variant.position.childId` — position is always lowercase. Check `setChildId()` was called. | `src/measurements/MeasurementContainer.js` → `getFlattenedOutput()` |
| `LatestWinsGate` promise never resolves | A superseded fire resolves with `{ superseded: true }`, not `undefined`. Branch on `r && r.superseded`. | `src/domain/LatestWinsGate.js` |
| Status badge stuck at grey | `getStatusBadge()` threw and `StatusUpdater` caught it. Look for `statusBadge.error(...)` in the container log. | `src/nodered/statusUpdater.js` |
> Never ship `enableLog: 'debug'` in a demo or production config — it fills the container log within seconds and obscures real errors.
---
## 12. When NOT to depend on this library
- **Passive HTTP gateway nodes** (e.g. `dashboardAPI`) may skip `BaseDomain` and `BaseNodeAdapter` entirely if they hold no domain state. A plain Node-RED node with HTTP endpoints needs only `logger`, `outputUtils`, and `configManager`. See the `dashboardAPI` wiki for the rationale.
- **External scripts or standalone tools** that need only unit conversion can import just `const { convert } = require('generalFunctions')` without pulling in the full domain stack.
- **Nodes at a different S88 level** that inherit from a third-party base class must not import from `src/domain/` or `src/nodered/` internal paths — they may only use root-level exports.
---
## 13. Known limitations
| # | Issue | Tracked in |
|---|---|---|
| 1 | `loadCurve` is deprecated; replacement `loadModel` exists but not all nodes have migrated | `OPEN_QUESTIONS.md` — Phase 8.5 cleanup |
| 2 | `outlierDetection` (`DynamicClusterDeviation`) prints to `console.log` internally — not routed through `logger` | Code review backlog |
| 3 | `configUtils.initConfig` strips unknown keys silently; schema must include every key the domain reads or defaults are lost | `OPEN_QUESTIONS.md` — e.g. monster schema fix 2026-05-11 |
| 4 | `state` (FSM) and `predict` are not yet integrated with `BaseDomain` lifecycle — nodes wire them manually in `configure()` | Architecture backlog |
| 5 | `menuUtils` / `MenuManager` are served as browser JavaScript and bypass the normal Node.js import path — deep changes require testing in both environments | `endpointUtils.js` |
| 6 | `CascadePIDController` has no dedicated test suite | Test backlog |
