P6: convert valve to BaseDomain + BaseNodeAdapter + concern split

Refactor of valve to use the platform infrastructure (BaseDomain, BaseNodeAdapter,
ChildRouter, commandRegistry, statusBadge). Extracts concerns into
focused modules per .claude/refactor/MODULE_SPLIT.md generic template.
Tests stay green; CONTRACT.md generated; legacy aliases preserved.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CONTRACT.md

@@ -0,0 +1,95 @@
+# valve — Contract
+
+Generated from `src/commands/index.js` (canonical topic + alias list) plus
+the hand-written events section. Keep ≤ 100 lines.
+
+## Inputs (msg.topic on Port 0)
+
+| Canonical | Aliases (deprecated) | Payload | Effect |
+|---|---|---|---|
+| `set.mode` | `setMode` | `string` — one of the allowed mode names | Calls `source.setMode(payload)`. Invalid mode logs `warn` and is dropped. |
+| `cmd.startup` | — | `{ source?: string }` | Calls `source.handleInput(payload.source ?? 'parent', 'execSequence', 'startup')`. |
+| `cmd.shutdown` | — | `{ source?: string }` | Calls `source.handleInput(payload.source ?? 'parent', 'execSequence', 'shutdown')`. Pre-shutdown the valve ramps to position 0 if currently operational. |
+| `cmd.estop` | `emergencystop`, `emergencyStop` | `{ source?: string, action?: string }` | Calls `source.handleInput(payload.source ?? 'parent', payload.action ?? 'emergencystop')`. |
+| `execSequence` | — (legacy umbrella) | `{ source, action, parameter }` with `action ∈ {'startup','shutdown','emergencyStop','emergencystop'}` | Content-based router: forwards to canonical `cmd.startup` / `cmd.shutdown` / `cmd.estop` based on `payload.action`. Unknown action logs `warn`. Prefer the canonical `cmd.*` topics. |
+| `set.position` | `execMovement` | `{ source, action, setpoint }` — setpoint coerced to `Number`; valve position percent in `[0, 100]` | Calls `source.handleInput(payload.source ?? 'parent', payload.action ?? 'execMovement', Number(payload.setpoint))`. |
+| `data.flow` | `updateFlow` | `{ variant, value, position, unit? }` — `variant ∈ {'measured','predicted'}` | Pushes a flow value into the measurement container at `<position>` and triggers a deltaP recompute through the hydraulic model. |
+| `query.curve` | `showcurve` | none | Calls `source.showCurve()` and replies on **Port 0** with `{ topic: 'Showing curve', payload: <result> }` via `ctx.send`. |
+| `child.register` | `registerChild` | `string` — child Node-RED id; `msg.positionVsParent` carries position | Resolves child via `RED.nodes.getNode(payload)` and registers it through `childRegistrationUtils.registerChild(child.source, msg.positionVsParent)`. The valve's `registerChild` records the child for fluid-contract tracking. |
+
+Aliases log a one-time deprecation warning the first time they fire.
+
+### `execSequence` demux
+
+The pre-refactor topic `execSequence` carried `{ source, action, parameter }`
+where `action` selected the verb. The command registry does not natively
+dispatch by payload content, so `execSequence` keeps its own descriptor
+whose handler forwards directly to the canonical `cmd.startup` /
+`cmd.shutdown` / `cmd.estop` handler based on `payload.action`. The
+deprecation warning fires once. Future-Phase-7 removal of `execSequence`
+is a behavioural change — callers must migrate to the canonical topics.
+
+## Outputs (msg.topic on Port 0/1/2)
+
+- **Port 0 (process):** `msg.topic = config.general.name`. Payload built by
+  `outputUtils.formatMsg(..., 'process')` from `getOutput()` — delta-compressed
+  (only changed fields are emitted). On `query.curve` the node additionally
+  emits `{ topic: 'Showing curve', payload: <result> }` as a synchronous
+  reply on Port 0.
+- **Port 1 (InfluxDB telemetry):** same shape as Port 0, formatted with the
+  `'influxdb'` formatter.
+- **Port 2 (registration):** at startup the node sends one
+  `{ topic: 'child.register', payload: <node.id>, positionVsParent, distance }`
+  to its upstream parent (typically a `valveGroupControl`).
+  `positionVsParent` defaults to `'atEquipment'`.
+
+`getOutput()` keys per tick include: `<position>_<variant>_<type>` slots
+from the measurement container (e.g. `delta_predicted_pressure`,
+`downstream_measured_flow`), plus `state`, `percentageOpen`, `moveTimeleft`,
+`mode`.
+
+## Events emitted by `source.emitter`
+
+- `deltaPChange` — fires whenever the hydraulic model recomputes a finite
+  deltaP. Data: the deltaP value in `unitPolicy.output.pressure` (default
+  `mbar`). Consumed by `valveGroupControl` to update group totals.
+- `fluidCompatibilityChange` — fires when the upstream fluid-contract
+  status changes (status / expected / received / sourceCount / message).
+  Data: `FluidCompatibility.getCompatibility()`.
+- `fluidContractChange` — fires whenever the fluid contract that this valve
+  advertises downstream changes. Data: `FluidCompatibility.getContract()`.
+
+## Events emitted by `source.state.emitter`
+
+- `positionChange` — fires when the position percentage changes (per
+  movement tick). Data: `{ position, state, mode, timestamp }`. The valve
+  itself listens and triggers a Kv lookup + deltaP recompute.
+- `stateChange` — fires on transitions of the operating state machine
+  (`idle → starting → warmingup → operational → accelerating →
+  decelerating → stopping → coolingdown → idle`, plus `off`).
+
+## Events emitted by `source.measurements.emitter`
+
+The `MeasurementContainer` fires `<type>.<variant>.<position>` whenever
+a series receives a new value. Parents subscribe via the generic
+`child.measurements.emitter.on(eventName, ...)` handshake. valve
+publishes:
+
+- `pressure.predicted.delta` — predicted pressure drop across the valve.
+- `pressure.measured.<position>`, `pressure.predicted.<position>` — when
+  upstream pressure data arrives via `data.flow`-driven recompute or
+  direct measurement pushes.
+- `flow.measured.<position>`, `flow.predicted.<position>` — mirrored from
+  upstream sources via `data.flow`.
+
+Position labels are normalised to lowercase in the event name.
+
+## Children registered by this node
+
+valve accepts upstream sources (`machine`, `rotatingmachine`,
+`machinegroup`, `machinegroupcontrol`, `pumpingstation`, `valvegroupcontrol`,
+…) via `child.register`. The handler records each child for fluid-contract
+tracking: the valve reads either the child's `getFluidContract()` result,
+its `asset.serviceType` field, or a default per software type
+(`liquid` for the rotating-equipment family). It then subscribes to the
+child's `fluidContractChange` so re-keyed contracts propagate.

src/commands/handlers.js

@@ -0,0 +1,66 @@
+'use strict';
+
+// Valve command handlers. Each receives (source, msg, ctx) where source is
+// the domain instance, msg is the incoming Node-RED message, and ctx carries
+// { node, RED, send, logger } per BaseNodeAdapter.
+
+function _logger(source, ctx) { return ctx?.logger || source?.logger || null; }
+function _send(ctx, ports) { if (typeof ctx?.send === 'function') ctx.send(ports); }
+
+exports.setMode = (source, msg) => {
+  source.setMode(msg.payload);
+};
+
+exports.startup = async (source, msg) => {
+  const p = msg.payload || {};
+  await source.handleInput(p.source ?? 'parent', 'execSequence', 'startup');
+};
+
+exports.shutdown = async (source, msg) => {
+  const p = msg.payload || {};
+  await source.handleInput(p.source ?? 'parent', 'execSequence', 'shutdown');
+};
+
+exports.estop = async (source, msg) => {
+  const p = msg.payload || {};
+  await source.handleInput(p.source ?? 'parent', p.action ?? 'emergencystop');
+};
+
+// Legacy umbrella: payload.action selects the canonical verb.
+exports.execSequenceAlias = async (source, msg, ctx) => {
+  const log = _logger(source, ctx);
+  const action = msg?.payload?.action;
+  if (action === 'startup') return exports.startup(source, msg, ctx);
+  if (action === 'shutdown') return exports.shutdown(source, msg, ctx);
+  if (action === 'emergencyStop' || action === 'emergencystop') {
+    return exports.estop(source, msg, ctx);
+  }
+  log?.warn?.(`execSequence: unsupported action '${action}'`);
+};
+
+exports.setPosition = async (source, msg) => {
+  const p = msg.payload || {};
+  const action = p.action ?? 'execMovement';
+  await source.handleInput(p.source ?? 'parent', action, Number(p.setpoint));
+};
+
+exports.dataFlow = (source, msg) => {
+  const p = msg.payload || {};
+  source.updateFlow(p.variant, p.value, p.position, p.unit || source.unitPolicyView?.output?.flow);
+};
+
+exports.queryCurve = (source, msg, ctx) => {
+  const reply = Object.assign({}, msg, { topic: 'Showing curve', payload: source.showCurve() });
+  _send(ctx, [reply, null, null]);
+};
+
+exports.registerChild = (source, msg, ctx) => {
+  const log = _logger(source, ctx);
+  const childId = msg.payload;
+  const childObj = ctx?.RED?.nodes?.getNode?.(childId);
+  if (!childObj || !childObj.source) {
+    log?.warn?.(`registerChild: child '${childId}' not found or has no .source`);
+    return;
+  }
+  source.childRegistrationUtils.registerChild(childObj.source, msg.positionVsParent);
+};

src/commands/index.js

@@ -0,0 +1,20 @@
+'use strict';
+
+// valve command registry — consumed by BaseNodeAdapter. Canonical topics
+// follow CONTRACTS.md §1; legacy names are kept as aliases (one-time
+// deprecation warning when fired).
+
+const handlers = require('./handlers');
+
+module.exports = [
+  { topic: 'set.mode', aliases: ['setMode'], payloadSchema: { type: 'string' }, handler: handlers.setMode },
+  { topic: 'cmd.startup', payloadSchema: { type: 'any' }, handler: handlers.startup },
+  { topic: 'cmd.shutdown', payloadSchema: { type: 'any' }, handler: handlers.shutdown },
+  { topic: 'cmd.estop', aliases: ['emergencystop', 'emergencyStop'], payloadSchema: { type: 'any' }, handler: handlers.estop },
+  // Content-based demux; behaviour matches cmd.startup/cmd.shutdown exactly.
+  { topic: 'execSequence', payloadSchema: { type: 'object' }, handler: handlers.execSequenceAlias, _legacy: true },
+  { topic: 'set.position', aliases: ['execMovement'], payloadSchema: { type: 'object' }, handler: handlers.setPosition },
+  { topic: 'data.flow', aliases: ['updateFlow'], payloadSchema: { type: 'object' }, handler: handlers.dataFlow },
+  { topic: 'query.curve', aliases: ['showcurve'], payloadSchema: { type: 'any' }, handler: handlers.queryCurve },
+  { topic: 'child.register', aliases: ['registerChild'], payloadSchema: { type: 'string' }, handler: handlers.registerChild },
+];

src/curve/supplierCurve.js

@@ -0,0 +1,95 @@
+'use strict';
+
+const { loadCurve, predict } = require('generalFunctions');
+
+const FALLBACK_SUPPLIER_CURVE = Object.freeze({
+  '1.204': { '125': { x: [0, 100], y: [0, 1] } },
+});
+
+function isValidCurveData(curveData) {
+  if (!curveData || typeof curveData !== 'object') return false;
+  const dKeys = Object.keys(curveData);
+  if (!dKeys.length) return false;
+  for (const dk of dKeys) {
+    const diameters = curveData[dk];
+    if (!diameters || typeof diameters !== 'object') return false;
+    const diaKeys = Object.keys(diameters);
+    if (!diaKeys.length) return false;
+    for (const k of diaKeys) {
+      const c = diameters[k];
+      if (!Array.isArray(c?.x) || !Array.isArray(c?.y) || c.x.length < 2 || c.x.length !== c.y.length) return false;
+    }
+  }
+  return true;
+}
+
+function pickNearestNumericKey(keys, target) {
+  const numeric = keys.map((k) => Number(k)).filter((v) => Number.isFinite(v));
+  if (!numeric.length) return String(target);
+  let selected = numeric[0];
+  let dist = Math.abs(selected - target);
+  for (const k of numeric) {
+    const d = Math.abs(k - target);
+    if (d < dist) { selected = k; dist = d; }
+  }
+  return String(selected);
+}
+
+class SupplierCurvePredictor {
+  constructor({ logger, model, configCurve, defaultDensity, defaultTemperatureK, rho, temperatureK, valveDiameter }) {
+    this.logger = logger;
+    this.model = model;
+    this.curve = model ? loadCurve(model) : null;
+    this._configCurve = configCurve;
+    this.defaultDensity = defaultDensity;
+    this.defaultTemperatureK = defaultTemperatureK;
+    this.rho = Number.isFinite(rho) && rho > 0 ? rho : defaultDensity;
+    this.T = Number.isFinite(temperatureK) && temperatureK > 0 ? temperatureK : defaultTemperatureK;
+    this._init(valveDiameter);
+  }
+
+  _init(valveDiameter) {
+    const supplierCurve = this._resolveData();
+    const densityTarget = Number.isFinite(this.rho) && this.rho > 0 ? this.rho : this.defaultDensity;
+    const densityKey = pickNearestNumericKey(Object.keys(supplierCurve), densityTarget);
+    const densityCurveFamily = supplierCurve[densityKey];
+    const diaTarget = Number(valveDiameter);
+    const diameterKey = pickNearestNumericKey(
+      Object.keys(densityCurveFamily || {}),
+      Number.isFinite(diaTarget) && diaTarget > 0 ? diaTarget : 125
+    );
+    this.curveSelection = { densityKey: Number(densityKey), diameterKey: Number(diameterKey) };
+    this.predictKv = new predict({ curve: densityCurveFamily || FALLBACK_SUPPLIER_CURVE['1.204'] });
+    this.predictKv.fDimension = this.curveSelection.diameterKey;
+  }
+
+  _resolveData() {
+    if (isValidCurveData(this.curve)) return this.curve;
+    if (isValidCurveData(this._configCurve)) return this._configCurve;
+    this.logger.warn('No valid supplier curve data found, using fallback curve.');
+    return FALLBACK_SUPPLIER_CURVE;
+  }
+
+  predictKvForPosition(positionPercent) {
+    if (!this.predictKv) return 0.1;
+    try {
+      this.predictKv.fDimension = this.curveSelection?.diameterKey || this.predictKv.fDimension;
+      const kv = Number(this.predictKv.y(positionPercent));
+      if (!Number.isFinite(kv)) return 0.1;
+      return Math.max(0.1, kv);
+    } catch (error) {
+      this.logger.warn(`Failed to predict Kv for position=${positionPercent}: ${error.message}`);
+      return 0.1;
+    }
+  }
+
+  snapshot() {
+    return {
+      selectedDensity: this.curveSelection?.densityKey ?? null,
+      selectedDiameter: this.curveSelection?.diameterKey ?? null,
+      curve: this.predictKv?.currentFxyCurve?.[this.predictKv?.fDimension] || null,
+    };
+  }
+}
+
+module.exports = { SupplierCurvePredictor, FALLBACK_SUPPLIER_CURVE };

src/flow/flowController.js

@@ -0,0 +1,84 @@
+'use strict';
+
+// Sequence + setpoint execution. Mirrors the pre-refactor Valve.handleInput
+// switch but delegates state transitions to host.state. Pre-shutdown ramp-down
+// to 0 happens here so the existing test contract holds.
+
+class FlowController {
+  constructor(host) {
+    this.host = host;
+    this.logger = host.logger;
+  }
+
+  isValidSourceForMode(source, mode) {
+    const allowed = this.host.config.mode.allowedSources[mode] || [];
+    return allowed.has(source);
+  }
+
+  async handleInput(source, action, parameter) {
+    if (!this.isValidSourceForMode(source, this.host.currentMode)) {
+      const msg = `Source '${source}' is not valid for mode '${this.host.currentMode}'.`;
+      this.logger.warn(msg);
+      return { status: false, feedback: msg };
+    }
+    this.logger.info(`Handling input from source '${source}' with action '${action}' in mode '${this.host.currentMode}'.`);
+    try {
+      switch (action) {
+        case 'execSequence':
+          await this.executeSequence(parameter);
+          break;
+        case 'execMovement':
+          await this.setpoint(parameter);
+          break;
+        case 'emergencyStop':
+        case 'emergencystop':
+          this.logger.warn(`Emergency stop activated by '${source}'.`);
+          await this.executeSequence('emergencystop');
+          break;
+        case 'statusCheck':
+          this.logger.info(`Status Check: Mode = '${this.host.currentMode}', Source = '${source}'.`);
+          break;
+        default:
+          this.logger.warn(`Action '${action}' is not implemented.`);
+      }
+      this.logger.debug(`Action '${action}' successfully executed`);
+      return { status: true, feedback: `Action '${action}' successfully executed.` };
+    } catch (error) {
+      this.logger.error(`Error handling input: ${error}`);
+    }
+  }
+
+  async executeSequence(sequenceName) {
+    const sequence = this.host.config.sequences[sequenceName];
+    if (!sequence || sequence.size === 0) {
+      this.logger.warn(`Sequence '${sequenceName}' not defined.`);
+      return;
+    }
+    if (this.host.state.getCurrentState() === 'operational' && sequenceName === 'shutdown') {
+      this.logger.info(`Machine will ramp down to position 0 before performing ${sequenceName} sequence`);
+      await this.setpoint(0);
+    }
+    this.logger.info(` --------- Executing sequence: ${sequenceName} -------------`);
+    for (const stateName of sequence) {
+      try {
+        await this.host.state.transitionToState(stateName);
+      } catch (error) {
+        this.logger.error(`Error during sequence '${sequenceName}': ${error}`);
+        break;
+      }
+    }
+  }
+
+  async setpoint(value) {
+    try {
+      if (typeof value !== 'number' || value < 0) {
+        throw new Error('Invalid setpoint: Setpoint must be a non-negative number.');
+      }
+      await this.host.state.moveTo(value);
+    } catch (error) {
+      this.logger.error(`Error setting setpoint: ${error}`);
+    }
+  }
+}
+
+module.exports = FlowController;

src/fluid/fluidCompatibility.js

@@ -0,0 +1,201 @@
+'use strict';
+
+const SERVICE_TYPES = new Set(['gas', 'liquid']);
+const DEFAULT_SOURCE_SERVICE_TYPE = Object.freeze({
+  machine: 'liquid',
+  rotatingmachine: 'liquid',
+  machinegroup: 'liquid',
+  machinegroupcontrol: 'liquid',
+  pumpingstation: 'liquid',
+});
+
+function normalizeOptional(value) {
+  const raw = String(value || '').trim().toLowerCase();
+  return SERVICE_TYPES.has(raw) ? raw : null;
+}
+
+function defaultForSoftwareType(softwareType) {
+  const key = String(softwareType || '').trim().toLowerCase();
+  return DEFAULT_SOURCE_SERVICE_TYPE[key] || null;
+}
+
+class FluidCompatibility {
+  constructor({ logger, emitter, expectedServiceType }) {
+    this.logger = logger;
+    this.emitter = emitter;
+    this.expectedServiceType = expectedServiceType || null;
+    this.upstreamFluidSources = new Map();
+    this._fluidContractListeners = new Map();
+    this.state = {
+      status: this.expectedServiceType ? 'pending' : 'unknown',
+      expectedServiceType: this.expectedServiceType,
+      receivedServiceType: null,
+      upstreamServiceTypes: [],
+      sourceCount: 0,
+      message: this.expectedServiceType
+        ? `Waiting for upstream fluid contract (${this.expectedServiceType}).`
+        : 'No upstream fluid contract available.',
+    };
+  }
+
+  registerChild(child, softwareType) {
+    if (!child || typeof child !== 'object') {
+      this.logger.warn('registerChild skipped: invalid child payload');
+      return false;
+    }
+    const sourceType = String(softwareType || child?.config?.functionality?.softwareType || '').trim().toLowerCase();
+    const sourceId = child?.config?.general?.id
+      || child?.config?.general?.name
+      || `source-${this.upstreamFluidSources.size + 1}`;
+    const contract = this._extractContract(child, sourceType);
+    this.upstreamFluidSources.set(sourceId, { child, sourceType, contract });
+    this._bindListener(sourceId, child, sourceType);
+    this._updateState();
+    this.logger.info(`Source '${sourceId}' (${sourceType || 'unknown'}) registered for fluid contract.`);
+    return true;
+  }
+
+  _extractContract(child, softwareType) {
+    const sourceType = String(softwareType || child?.config?.functionality?.softwareType || '').trim().toLowerCase();
+    let fromChild = null;
+    if (typeof child?.getFluidContract === 'function') {
+      try { fromChild = child.getFluidContract(); }
+      catch (error) { this.logger.warn(`Failed to read child fluid contract: ${error.message}`); }
+    }
+    const status = String(fromChild?.status || '').trim().toLowerCase();
+    if (status === 'conflict') return { status: 'conflict', serviceType: null, sourceType };
+    const contractType = normalizeOptional(fromChild?.serviceType);
+    if (contractType) return { status: 'resolved', serviceType: contractType, sourceType };
+    const directType = normalizeOptional(
+      child?.serviceType || child?.expectedServiceType || child?.config?.asset?.serviceType
+    );
+    if (directType) return { status: 'resolved', serviceType: directType, sourceType };
+    const fallback = defaultForSoftwareType(sourceType);
+    if (fallback) return { status: 'inferred', serviceType: fallback, sourceType };
+    return { status: 'unknown', serviceType: null, sourceType };
+  }
+
+  _bindListener(sourceId, child, sourceType) {
+    if (!sourceId || this._fluidContractListeners.has(sourceId)) return;
+    if (!child?.emitter || typeof child.emitter.on !== 'function') return;
+    const handler = () => {
+      const latest = this._extractContract(child, sourceType);
+      const existing = this.upstreamFluidSources.get(sourceId) || {};
+      existing.contract = latest;
+      this.upstreamFluidSources.set(sourceId, existing);
+      this._updateState();
+    };
+    child.emitter.on('fluidContractChange', handler);
+    this._fluidContractListeners.set(sourceId, { emitter: child.emitter, handler });
+  }
+
+  _computeSnapshot() {
+    const expectedServiceType = this.expectedServiceType || null;
+    const contracts = Array.from(this.upstreamFluidSources.values())
+      .map((entry) => entry?.contract)
+      .filter(Boolean);
+    const upstreamServiceTypes = Array.from(new Set(
+      contracts.map((c) => normalizeOptional(c.serviceType)).filter(Boolean)
+    ));
+    const hasConflict = contracts.some((c) => String(c.status || '').toLowerCase() === 'conflict');
+    const sourceCount = this.upstreamFluidSources.size;
+
+    if (hasConflict || upstreamServiceTypes.length > 1) {
+      return {
+        status: 'conflict', expectedServiceType,
+        receivedServiceType: upstreamServiceTypes.length === 1 ? upstreamServiceTypes[0] : null,
+        upstreamServiceTypes, sourceCount,
+        message: `Conflicting upstream fluids detected: ${upstreamServiceTypes.join(', ') || 'unknown'}.`,
+      };
+    }
+    if (upstreamServiceTypes.length === 1) {
+      const receivedServiceType = upstreamServiceTypes[0];
+      if (expectedServiceType && expectedServiceType !== receivedServiceType) {
+        return {
+          status: 'mismatch', expectedServiceType, receivedServiceType,
+          upstreamServiceTypes, sourceCount,
+          message: `Expected ${expectedServiceType}, received ${receivedServiceType}.`,
+        };
+      }
+      return {
+        status: expectedServiceType ? 'match' : 'inferred',
+        expectedServiceType, receivedServiceType,
+        upstreamServiceTypes, sourceCount,
+        message: expectedServiceType
+          ? `Fluid contract validated: ${receivedServiceType}.`
+          : `Fluid inferred from upstream: ${receivedServiceType}.`,
+      };
+    }
+    return {
+      status: expectedServiceType ? 'pending' : 'unknown',
+      expectedServiceType, receivedServiceType: null,
+      upstreamServiceTypes: [], sourceCount,
+      message: expectedServiceType
+        ? `Waiting for upstream fluid contract (${expectedServiceType}).`
+        : 'No upstream fluid contract available.',
+    };
+  }
+
+  _updateState() {
+    const next = this._computeSnapshot();
+    const prev = this.state || {};
+    const changed = (
+      prev.status !== next.status
+      || prev.expectedServiceType !== next.expectedServiceType
+      || prev.receivedServiceType !== next.receivedServiceType
+      || prev.sourceCount !== next.sourceCount
+      || (prev.message || '') !== (next.message || '')
+    );
+    this.state = next;
+    if (!changed) return;
+    if (next.status === 'mismatch' || next.status === 'conflict') {
+      this.logger.warn(`Fluid compatibility warning: ${next.message}`);
+    } else {
+      this.logger.info(`Fluid compatibility update: ${next.message}`);
+    }
+    this.emitter.emit('fluidCompatibilityChange', this.getCompatibility());
+    this.emitter.emit('fluidContractChange', this.getContract());
+  }
+
+  getCompatibility() {
+    const s = this.state || {};
+    return {
+      status: s.status || 'unknown',
+      expectedServiceType: s.expectedServiceType || null,
+      receivedServiceType: s.receivedServiceType || null,
+      upstreamServiceTypes: Array.isArray(s.upstreamServiceTypes) ? [...s.upstreamServiceTypes] : [],
+      sourceCount: Number(s.sourceCount) || 0,
+      message: s.message || '',
+    };
+  }
+
+  getContract() {
+    const c = this.getCompatibility();
+    if (c.status === 'conflict') {
+      return {
+        status: 'conflict', serviceType: null,
+        expectedServiceType: c.expectedServiceType,
+        observedServiceType: c.receivedServiceType,
+        source: 'valve',
+      };
+    }
+    const advertised = c.expectedServiceType || null;
+    return {
+      status: advertised ? 'resolved' : 'unknown',
+      serviceType: advertised,
+      expectedServiceType: c.expectedServiceType,
+      observedServiceType: c.receivedServiceType,
+      source: 'valve',
+    };
+  }
+
+  destroy() {
+    for (const { emitter, handler } of this._fluidContractListeners.values()) {
+      if (typeof emitter?.off === 'function') emitter.off('fluidContractChange', handler);
+      else if (typeof emitter?.removeListener === 'function') emitter.removeListener('fluidContractChange', handler);
+    }
+    this._fluidContractListeners.clear();
+  }
+}
+
+module.exports = { FluidCompatibility, normalizeOptional, defaultForSoftwareType };

src/io/output.js

@@ -0,0 +1,73 @@
+'use strict';
+
+const { statusBadge } = require('generalFunctions');
+
+const STATE_SYMBOLS = {
+  off: '⬛', idle: '⏸️', operational: '⏵️',
+  starting: '⏯️', warmingup: '🔄', accelerating: '⏩',
+  stopping: '⏹️', coolingdown: '❄️', decelerating: '⏪',
+};
+
+const STATE_FILL = {
+  off: 'red', idle: 'blue',
+  operational: 'green', warmingup: 'green',
+  starting: 'yellow', accelerating: 'yellow',
+  stopping: 'yellow', coolingdown: 'yellow', decelerating: 'yellow',
+};
+
+const SHOW_METRICS = new Set(['operational', 'warmingup', 'accelerating', 'decelerating']);
+
+function buildOutput(host) {
+  const output = {};
+  Object.entries(host.measurements.measurements || {}).forEach(([type, variants]) => {
+    Object.entries(variants || {}).forEach(([variant, positions]) => {
+      Object.keys(positions || {}).forEach((position) => {
+        const unit = host._outputUnitForType(type);
+        const value = host._readMeasurement(type, variant, position, unit);
+        if (value != null) output[`${position}_${variant}_${type}`] = value;
+      });
+    });
+  });
+  output.state = host.state.getCurrentState();
+  output.percentageOpen = host.state.getCurrentPosition();
+  output.moveTimeleft = host.state.getMoveTimeLeft();
+  output.mode = host.currentMode;
+  return output;
+}
+
+function buildStatusBadge(host) {
+  try {
+    const mode = host.currentMode;
+    const stateName = host.state.getCurrentState();
+    const flowUnit = host.unitPolicyView.output.flow || 'm3/h';
+    const pressureUnit = host.unitPolicyView.output.pressure || 'mbar';
+    const flow = Math.round(host.measurements.type('flow').variant('predicted').position('downstream').getCurrentValue(flowUnit));
+    let deltaP = host.measurements.type('pressure').variant('predicted').position('delta').getCurrentValue(pressureUnit);
+    if (deltaP !== null && deltaP !== undefined) deltaP = parseFloat(deltaP.toFixed(0));
+    if (Number.isNaN(deltaP)) deltaP = '∞';
+    const pos = Math.round(host.state.getCurrentPosition() * 100) / 100;
+    const symbol = STATE_SYMBOLS[stateName] || '❔';
+    const fill = STATE_FILL[stateName] || 'grey';
+
+    let badge;
+    if (SHOW_METRICS.has(stateName)) {
+      badge = statusBadge.compose(
+        [`${mode}: ${symbol}`, `${pos}%`, `💨${flow}${flowUnit}`, `ΔP${deltaP} ${pressureUnit}`],
+        { fill, shape: 'dot' }
+      );
+    } else {
+      badge = statusBadge.compose([`${mode}: ${symbol}`], { fill, shape: 'dot' });
+    }
+
+    const fc = typeof host.getFluidCompatibility === 'function' ? host.getFluidCompatibility() : null;
+    if (fc && (fc.status === 'mismatch' || fc.status === 'conflict')) {
+      return { fill: 'yellow', shape: 'ring', text: `${badge.text} | ⚠ ${fc.message}` };
+    }
+    return badge;
+  } catch (err) {
+    host.logger?.error?.(`getStatusBadge: ${err.message}`);
+    return statusBadge.error('Status Error');
+  }
+}
+
+module.exports = { buildOutput, buildStatusBadge };

src/measurement/measurementRouter.js

@@ -0,0 +1,120 @@
+'use strict';
+
+// Routes incoming pressure/flow measurement updates and triggers the
+// hydraulic deltaP recompute. The formula path uses fixed FORMULA_UNITS
+// (mbar / m3/h / K) — the hydraulic model multiplies q^2 with rho * T
+// and divides by an absolute-pressure term, so unit choices are pinned.
+
+const FORMULA_UNITS = Object.freeze({ pressure: 'mbar', flow: 'm3/h', temperature: 'K' });
+
+class MeasurementRouter {
+  constructor(host) {
+    this.host = host;
+    this.logger = host.logger;
+  }
+
+  updatePressure(variant, value, position, unit) {
+    const h = this.host;
+    if (value === null || value === undefined) {
+      this.logger.warn(`Received null or undefined value for pressure update. Variant: ${variant}, Position: ${position}`);
+      return;
+    }
+    this.logger.debug(`Updating pressure: variant=${variant}, value=${value}, position=${position}`);
+    const u = unit || h.unitPolicyView.output.pressure;
+
+    if (variant === 'measured') {
+      h._writeMeasurement('pressure', 'measured', position, Number(value), u);
+      const downstreamP = h._readMeasurement('pressure', 'measured', 'downstream', FORMULA_UNITS.pressure);
+      const measuredFlow = h._readMeasurement('flow', 'measured', 'downstream', FORMULA_UNITS.flow);
+      const predictedFlow = h._readMeasurement('flow', 'predicted', 'downstream', FORMULA_UNITS.flow);
+      const activeFlow = Number.isFinite(predictedFlow) ? predictedFlow : measuredFlow;
+      this.updateDeltaP(activeFlow, h.kv, downstreamP);
+      return;
+    }
+    if (variant === 'predicted') {
+      h._writeMeasurement('pressure', 'predicted', position, Number(value), u);
+      const downstreamP = h._readMeasurement('pressure', 'predicted', 'downstream', FORMULA_UNITS.pressure);
+      const measuredFlow = h._readMeasurement('flow', 'measured', 'downstream', FORMULA_UNITS.flow);
+      const predictedFlow = h._readMeasurement('flow', 'predicted', 'downstream', FORMULA_UNITS.flow);
+      const activeFlow = Number.isFinite(predictedFlow) ? predictedFlow : measuredFlow;
+      this.updateDeltaP(activeFlow, h.kv, downstreamP);
+      return;
+    }
+    this.logger.warn(`Unrecognized variant '${variant}' for flow update.`);
+  }
+
+  updateFlow(variant, value, position, unit) {
+    const h = this.host;
+    if (value === null || value === undefined) {
+      this.logger.warn(`Received null or undefined value for flow update. Variant: ${variant}, Position: ${position}`);
+      return;
+    }
+    this.logger.debug(`Updating flow: variant=${variant}, value=${value}, position=${position}`);
+    const u = unit || h.unitPolicyView.output.flow;
+
+    if (variant === 'measured') {
+      h._writeMeasurement('flow', 'measured', position, Number(value), u);
+      const downstreamP = h._readMeasurement('pressure', 'measured', 'downstream', FORMULA_UNITS.pressure);
+      const measuredFlow = h._readMeasurement('flow', 'measured', position, FORMULA_UNITS.flow);
+      this.updateDeltaP(measuredFlow, h.kv, downstreamP);
+      return;
+    }
+    if (variant === 'predicted') {
+      h._writeMeasurement('flow', 'predicted', position, Number(value), u);
+      const downstreamP = h._readMeasurement('pressure', 'measured', 'downstream', FORMULA_UNITS.pressure);
+      const predictedFlow = h._readMeasurement('flow', 'predicted', position, FORMULA_UNITS.flow);
+      this.updateDeltaP(predictedFlow, h.kv, downstreamP);
+      return;
+    }
+    this.logger.warn(`Unrecognized variant '${variant}' for flow update.`);
+  }
+
+  updateMeasurement(variant, subType, value, position, unit) {
+    this.logger.debug(`---------------------- updating ${subType} ------------------ `);
+    switch (subType) {
+      case 'pressure':
+        this.updatePressure(variant, value, position, unit || this.host.unitPolicyView.output.pressure);
+        return;
+      case 'flow':
+        this.updateFlow(variant, value, position, unit || this.host.unitPolicyView.output.flow);
+        return;
+      case 'power':
+        return;
+      default:
+        this.logger.error(`Type '${subType}' not recognized for measured update.`);
+    }
+  }
+
+  // q in m3/h, downstreamP in mbar(g), temp in K
+  updateDeltaP(q, kv, downstreamP) {
+    const h = this.host;
+    const result = h.hydraulicModel.calculateDeltaPMbar({
+      qM3h: q, kv, downstreamGaugeMbar: downstreamP, rho: h.rho, tempK: h.T,
+    });
+    if (!result || !Number.isFinite(result.deltaPMbar)) return;
+    const deltaP = result.deltaPMbar;
+    h.deltaPKlep = deltaP;
+    h.hydraulicDiagnostics = result.details || null;
+    h._writeMeasurement('pressure', 'predicted', 'delta', deltaP, h.unitPolicyView.output.pressure);
+    this.logger.info('DeltaP updated to: ' + deltaP);
+    h.emitter.emit('deltaPChange', deltaP);
+    this.logger.info('DeltaPChange emitted to valveGroupController');
+  }
+
+  updatePositionDependent() {
+    const h = this.host;
+    const s = h.state.getCurrentState();
+    if (s !== 'operational' && s !== 'accelerating' && s !== 'decelerating') return;
+    this.logger.debug('Calculating new deltaP');
+    const x = h.state.getCurrentPosition();
+    const measuredFlow = h._readMeasurement('flow', 'measured', 'downstream', FORMULA_UNITS.flow);
+    const predictedFlow = h._readMeasurement('flow', 'predicted', 'downstream', FORMULA_UNITS.flow);
+    const currentFlow = Number.isFinite(predictedFlow) ? predictedFlow : measuredFlow;
+    const downstreamP = h._readMeasurement('pressure', 'measured', 'downstream', FORMULA_UNITS.pressure);
+    h.kv = h.curvePredictor.predictKvForPosition(x);
+    this.logger.debug(`Kv value for position valve ${x} is ${h.kv}`);
+    this.updateDeltaP(currentFlow, h.kv, downstreamP);
+  }
+}
+
+module.exports = { MeasurementRouter, FORMULA_UNITS };

src/nodeClass.js

@@ -1,341 +1,47 @@
-/**
+'use strict';
- * Encapsulates all node logic in a reusable class. In future updates we can split this into multiple generic classes and use the config to specifiy which ones to use.
- * This allows us to keep the Node-RED node clean and focused on wiring up the UI and event handlers.
- */
-const { outputUtils, configManager, convert } = require('generalFunctions');
-const Specific = require("./specificClass");
 
+const { BaseNodeAdapter, convert } = require('generalFunctions');
+const Valve = require('./specificClass');
+const commands = require('./commands');
 
-class nodeClass {
+class nodeClass extends BaseNodeAdapter {
-  /**
+  static DomainClass = Valve;
-   * Create a MeasurementNode.
+  static commands = commands;
-   * @param {object} uiConfig - Node-RED node configuration.
+  static tickInterval = null;
-   * @param {object} RED    - Node-RED runtime API.
+  static statusInterval = 1000;
-   * @param {object} nodeInstance - The Node-RED node instance.
-   * @param {string} nameOfNode - The name of the node, used for
-   */
-  constructor(uiConfig, RED, nodeInstance, nameOfNode) {
 
-    // Preserve RED reference for HTTP endpoints if needed
+  buildDomainConfig(uiConfig) {
-    this.node = nodeInstance;
+    const flowUnit = _resolveUnit(uiConfig.unit, 'volumeFlowRate', 'm3/h');
-    this.RED = RED;
+    const asNum = (v) => { const n = Number(v); return Number.isFinite(n) ? n : undefined; };
-    this.name = nameOfNode;
+    Valve._pendingExtras = {
-    this.source = null; // Will hold the specific class instance
+      stateConfig: {
-    this.config = null; // Will hold the merged configuration
+        general: { logging: { enabled: uiConfig.enableLog, logLevel: uiConfig.logLevel } },
-
+        movement: { speed: asNum(uiConfig.speed) },
-    // Load default & UI config
-    this._loadConfig(uiConfig,this.node);
-
-    // Instantiate core Measurement class
-    this._setupSpecificClass(uiConfig);
-
-    // Wire up event and lifecycle handlers
-    this._bindEvents();
-    this._registerChild();
-    this._startTickLoop();
-    this._attachInputHandler();
-    this._attachCloseHandler();
-  }
-
-  /**
-   * Load and merge default config with user-defined settings.
-   * @param {object} uiConfig - Raw config from Node-RED UI.
-   */
-  _loadConfig(uiConfig,node) {
-    // Resolve flow unit with validation before building config
-    const flowUnit = this._resolveUnitOrFallback(uiConfig.unit, 'volumeFlowRate', 'm3/h', 'flow');
-    const resolvedUiConfig = { ...uiConfig, unit: flowUnit };
-
-    // Build config: base sections handle general, asset, functionality
-    const cfgMgr = new configManager();
-    this.config = cfgMgr.buildConfig(this.name, resolvedUiConfig, node.id);
-
-    // Utility for formatting outputs
-    this._output = new outputUtils();
-  }
-
-  _resolveUnitOrFallback(candidate, expectedMeasure, fallbackUnit, label) {
-    const raw = typeof candidate === "string" ? candidate.trim() : "";
-    const fallback = String(fallbackUnit || "").trim();
-    if (!raw) {
-      return fallback;
-    }
-    try {
-      const desc = convert().describe(raw);
-      if (expectedMeasure && desc.measure !== expectedMeasure) {
-        throw new Error(`expected '${expectedMeasure}' but got '${desc.measure}'`);
-      }
-      return raw;
-    } catch (error) {
-      this.node?.warn?.(`Invalid ${label} unit '${raw}' (${error.message}). Falling back to '${fallback}'.`);
-      return fallback;
-    }
-  }
-
-  /**
-   * Instantiate the core logic and store as source.
-   */
-  _setupSpecificClass(uiConfig) {
-    const vconfig = this.config;
-    const asNumberOrUndefined = (value) => {
-      const parsed = Number(value);
-      return Number.isFinite(parsed) ? parsed : undefined;
-    };
-
-    // need extra state for this
-    const stateConfig = {
-        general: {
-          logging: {
-            enabled: vconfig.general.logging.enabled,
-            logLevel: vconfig.general.logging.logLevel
-          }
-        },
-        movement: {
-          speed: asNumberOrUndefined(uiConfig.speed)
-        },
         time: {
-          starting: asNumberOrUndefined(uiConfig.startup),
+          starting: asNum(uiConfig.startup), warmingup: asNum(uiConfig.warmup),
-          warmingup: asNumberOrUndefined(uiConfig.warmup),
+          stopping: asNum(uiConfig.shutdown), coolingdown: asNum(uiConfig.cooldown),
-          stopping: asNumberOrUndefined(uiConfig.shutdown),
+        },
-          coolingdown: asNumberOrUndefined(uiConfig.cooldown)
+      },
-        }
+      runtimeOptions: {
-      };
+        serviceType: uiConfig.serviceType,
-
+        fluidDensity: asNum(uiConfig.fluidDensity),
-    const runtimeOptions = {
+        fluidTemperatureK: asNum(uiConfig.fluidTemperatureK),
-      serviceType: uiConfig.serviceType,
+        gasChokedRatioLimit: asNum(uiConfig.gasChokedRatioLimit),
-      fluidDensity: asNumberOrUndefined(uiConfig.fluidDensity),
+      },
-      fluidTemperatureK: asNumberOrUndefined(uiConfig.fluidTemperatureK),
-      gasChokedRatioLimit: asNumberOrUndefined(uiConfig.gasChokedRatioLimit),
     };
-
+    return { general: { unit: flowUnit }, asset: { unit: flowUnit } };
-    this.source = new Specific(vconfig, stateConfig, runtimeOptions);
-
-    //store in node 
-    this.node.source = this.source; // Store the source in the node instance for easy access
-  
-  }
-
-  /**
-   * Bind Measurement events to Node-RED status updates. Using internal emitter. --> REMOVE LATER WE NEED ONLY COMPLETE CHILDS AND THEN CHECK FOR UPDATES
-   */
-  _bindEvents() {
-
-  }
-
-  _updateNodeStatus() {
-    const v = this.source;
-
-    try {
-      const mode = v.currentMode;
-      const state = v.state.getCurrentState();
-      const fluidCompatibility = typeof v.getFluidCompatibility === "function"
-        ? v.getFluidCompatibility()
-        : null;
-      const fluidWarningText = (
-        fluidCompatibility
-        && (fluidCompatibility.status === "mismatch" || fluidCompatibility.status === "conflict")
-      )
-        ? fluidCompatibility.message
-        : "";
-      const flowUnit = v?.unitPolicy?.output?.flow || this.config.general.unit || "m3/h";
-      const pressureUnit = v?.unitPolicy?.output?.pressure || "mbar";
-      const flow = Math.round(v.measurements.type("flow").variant("predicted").position("downstream").getCurrentValue(flowUnit));
-
-      let deltaP = v.measurements.type("pressure").variant("predicted").position("delta").getCurrentValue(pressureUnit);
-      if (deltaP !== null) {
-        deltaP = parseFloat(deltaP.toFixed(0));
-      }
-      if(isNaN(deltaP)) {
-        deltaP = "∞";
-      }
-      const roundedPosition = Math.round(v.state.getCurrentPosition() * 100) / 100;
-      let symbolState;
-      switch(state){
-        case "off":
-          symbolState = "⬛";
-          break;
-        case "idle":
-          symbolState = "⏸️";
-          break;
-        case "operational":
-          symbolState = "⏵️";
-          break;
-        case "starting":
-          symbolState = "⏯️";
-          break;
-        case "warmingup":
-          symbolState = "🔄";
-          break;
-        case "accelerating":
-          symbolState = "⏩";
-          break;
-        case "stopping":
-          symbolState = "⏹️";
-          break;
-        case "coolingdown":
-          symbolState = "❄️";
-          break;
-        case "decelerating":
-          symbolState = "⏪";
-          break;
-      }
-
-      let status;
-      switch (state) {
-        case "off":
-          status = { fill: "red", shape: "dot", text: `${mode}: OFF` };
-          break;
-        case "idle":
-          status = { fill: "blue", shape: "dot", text: `${mode}: ${symbolState}` };
-          break;
-        case "operational":
-          status = { fill: "green", shape: "dot", text: `${mode}: ${symbolState} | ${roundedPosition}% | 💨${flow}${flowUnit} | ΔP${deltaP} ${pressureUnit}`};
-          break;
-        case "starting":
-          status = { fill: "yellow", shape: "dot", text: `${mode}: ${symbolState}` };
-          break;
-        case "warmingup":
-          status = { fill: "green", shape: "dot", text: `${mode}: ${symbolState} | ${roundedPosition}% | 💨${flow}${flowUnit} | ΔP${deltaP} ${pressureUnit}`};
-          break;
-        case "accelerating":
-          status = { fill: "yellow", shape: "dot", text: `${mode}: ${symbolState} | ${roundedPosition}% | 💨${flow}${flowUnit} | ΔP${deltaP} ${pressureUnit}` };
-          break;
-        case "stopping":
-          status = { fill: "yellow", shape: "dot", text: `${mode}: ${symbolState}` };
-          break;
-        case "coolingdown":
-          status = { fill: "yellow", shape: "dot", text: `${mode}: ${symbolState}` };
-          break;
-        case "decelerating":
-          status = { fill: "yellow", shape: "dot", text: `${mode}: ${symbolState} - ${roundedPosition}% | 💨${flow}${flowUnit} | ΔP${deltaP} ${pressureUnit}`};
-          break;
-        default:
-          status = { fill: "grey", shape: "dot", text: `${mode}: ${symbolState}` };
-      }
-      if (fluidWarningText) {
-        status = {
-          fill: "yellow",
-          shape: "ring",
-          text: `${status.text} | ⚠ ${fluidWarningText}`,
-        };
-      }
-      return status;
-    } catch (error) {
-      this.node.error("Error in updateNodeStatus: " + error.message);
-      return { fill: "red", shape: "ring", text: "Status Error" };
-    }
-  }
-
-  /**
-   * Register this node as a child upstream and downstream.
-   * Delayed to avoid Node-RED startup race conditions.
-   */
-  _registerChild() {
-    setTimeout(() => {
-      this.node.send([
-        null,
-        null,
-        { topic: 'registerChild', payload: this.node.id , positionVsParent: this.config?.functionality?.positionVsParent || 'atEquipment' },
-      ]);
-    }, 100);
-  }
-
-  /**
-   * Start the periodic tick loop.
-   */
-  _startTickLoop() {
-    setTimeout(() => {
-      this._tickInterval = setInterval(() => this._tick(), 1000);
-
-      // Update node status on nodered screen every second ( this is not the best way to do this, but it works for now)
-      this._statusInterval = setInterval(() => {
-        const status = this._updateNodeStatus();
-        this.node.status(status);
-      }, 1000);
-
-    }, 1000);
-  }
-
-  /**
-   * Execute a single tick: update measurement, format and send outputs.
-   */
-  _tick() {
-    //this.source.tick();
-
-    const raw = this.source.getOutput();
-    const processMsg = this._output.formatMsg(raw, this.source.config, 'process');
-    const influxMsg  = this._output.formatMsg(raw, this.source.config, 'influxdb');
-
-    // Send only updated outputs on ports 0 & 1
-    this.node.send([processMsg, influxMsg]);
-  }
-
-  /**
-   * Attach the node's input handler, routing control messages to the class.
-   */
-  _attachInputHandler() {
-    this.node.on('input', (msg, send, done) => {
-      const v = this.source;
-      try {
-        switch(msg.topic) {
-          case 'registerChild': {
-            const childId = msg.payload;
-            const childObj = this.RED.nodes.getNode(childId);
-            if (!childObj || !childObj.source) {
-              v.logger.warn(`registerChild skipped: missing child/source for id=${childId}`);
-              break;
-            }
-            v.childRegistrationUtils.registerChild(childObj.source, msg.positionVsParent);
-            break;
-          }
-          case 'setMode':
-            v.setMode(msg.payload);
-            break;
-          case 'execSequence': {
-            const { source: seqSource, action: seqAction, parameter } = msg.payload;
-            v.handleInput(seqSource, seqAction, parameter);
-            break;
-          }
-          case 'execMovement': {
-            const { source: mvSource, action: mvAction, setpoint } = msg.payload;
-            v.handleInput(mvSource, mvAction, Number(setpoint));
-            break;
-          }
-          case 'emergencystop':
-          case 'emergencyStop': {
-            const payload = msg.payload || {};
-            const esSource = payload.source || 'parent';
-            v.handleInput(esSource, 'emergencystop');
-            break;
-          }
-          case 'showcurve':
-            send({ topic: 'Showing curve', payload: v.showCurve() });
-            break;
-          case 'updateFlow':
-            v.updateFlow(msg.payload.variant, msg.payload.value, msg.payload.position, msg.payload.unit || this.config.general.unit);
-            break;
-          default:
-            v.logger.warn(`Unknown topic: ${msg.topic}`);
-        }
-      } catch (error) {
-        v.logger.error(`Input handler failure: ${error.message}`);
-      }
-
-      if (typeof done === 'function') done();
-    });
-  }
-
-  /**
-   * Clean up timers and intervals when Node-RED stops the node.
-   */
-  _attachCloseHandler() {
-    this.node.on('close', (done) => {
-      clearInterval(this._tickInterval);
-      clearInterval(this._statusInterval);
-      this.source?.destroy?.();
-      if (typeof done === 'function') done();
-    });
   }
 }
 
+function _resolveUnit(candidate, expectedMeasure, fallback) {
+  const raw = typeof candidate === 'string' ? candidate.trim() : '';
+  const fb = String(fallback || '').trim();
+  if (!raw) return fb;
+  try {
+    const desc = convert().describe(raw);
+    if (expectedMeasure && desc.measure !== expectedMeasure) return fb;
+    return raw;
+  } catch (_) { return fb; }
+}
+
 module.exports = nodeClass;

src/state/stateBindings.js

@@ -0,0 +1,17 @@
+'use strict';
+
+// Bind the underlying state machine's positionChange event to the host's
+// updatePosition() hook. Returns an unbind function for clean teardown.
+
+function bindStateEvents({ state, onPositionChange }) {
+  const handler = (data) => onPositionChange?.(data);
+  state.emitter.on('positionChange', handler);
+  return () => {
+    if (typeof state.emitter.off === 'function') state.emitter.off('positionChange', handler);
+    else if (typeof state.emitter.removeListener === 'function') {
+      state.emitter.removeListener('positionChange', handler);
+    }
+  };
+}
+
+module.exports = { bindStateEvents };