feat(diffuser): resolve supplier curves via assetResolver + wire asset menu

_loadSpecs() now calls loadCurve(model) instead of returning a hardcoded
literal. Default model 'gva-elastox-r' keeps the legacy GVA numbers; the
editor cascade (supplier → type → model → unit) lets users pick Jäger,
Aerostrip, or PIK/PRK once those curve files land in generalFunctions.

Editor changes:
- diffuser.js serves /diffuser/menu.js + /diffuser/configData.js
- diffuser.html loads the shared MenuManager scripts, includes
  asset-fields-placeholder + logger-fields-placeholder, and runs the
  shared init/save lifecycle.
- Density field re-labelled "Bottom coverage [%]" — semantics were
  always meant to be % surface-area coverage; "elements per m²" was a
  prior mis-conversion. Default flipped 2.4 → 15 (typical fine-bubble).
- New defaults: model, unit, assetTagNumber.

specificClass:
- buildDomainConfig now forwards uiConfig.model/unit/assetTagNumber
  under config.asset.* so _loadSpecs can resolve it.
- _loadSpecs walks config.asset.model || config.model || DEFAULT, falls
  through to GVA on a missing curve file (with a clear error if neither
  resolves to a usable otr_curve + p_curve).

All 8 unit + structure tests pass.

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

diffuser.html

@@ -1,17 +1,29 @@
+<!-- Load the dynamic menu & config endpoints (asset cascade + logger fields) -->
+<script src="/diffuser/menu.js"></script>
+<script src="/diffuser/configData.js"></script>
+
 <script type="text/javascript">
 RED.nodes.registerType('diffuser', {
-  category: 'wbd typical',
+  category: 'EVOLV',
   color: '#86bbdd',
   defaults: {
     name: { value: '', required: true },
     number: { value: 1, required: true },
     i_elements: { value: 1, required: true },
-    i_diff_density: { value: 2.4, required: true },
+    i_diff_density: { value: 15, required: true },
     i_m_water: { value: 0, required: true },
     alfaf: { value: 0.7, required: true },
     i_zone_volume: { value: 0, required: false },
     processOutputFormat: { value: 'process' },
     dbaseOutputFormat: { value: 'influxdb' },
+
+    // Asset identifier surface. supplier / assetType / category are derived
+    // at runtime via assetResolver.resolveAssetMetadata(model); do NOT add
+    // them back here. See generalFunctions/src/registry/README.md.
+    assetTagNumber: { value: '' },
+    model: { value: '' },
+    unit: { value: '' },
+
     enableLog: { value: false },
     logLevel: { value: 'error' },
   },
@@ -21,7 +33,36 @@ RED.nodes.registerType('diffuser', {
   outputLabels: ['process', 'dbase', 'parent'],
   icon: 'font-awesome/fa-tint',
   label: function() {
-    return this.name ? `${this.name}_${this.number}` : 'diffuser';
+    const stem = this.model ? this.model : (this.name || 'diffuser');
+    return this.name ? `${this.name}_${this.number}` : stem;
+  },
+
+  oneditprepare: function() {
+    // wait for the menu scripts to load, then hand the node off to the
+    // shared asset / logger init code from generalFunctions
+    let menuRetries = 0;
+    const maxMenuRetries = 100; // 5 s at 50 ms intervals
+    const waitForMenuData = () => {
+      if (window.EVOLV?.nodes?.diffuser?.initEditor) {
+        window.EVOLV.nodes.diffuser.initEditor(this);
+      } else if (++menuRetries < maxMenuRetries) {
+        setTimeout(waitForMenuData, 50);
+      } else {
+        console.warn('diffuser: menu scripts failed to load within 5 seconds');
+      }
+    };
+    waitForMenuData();
+  },
+
+  oneditsave: function() {
+    // Asset cascade saves model + unit + assetTagNumber
+    if (window.EVOLV?.nodes?.diffuser?.assetMenu?.saveEditor) {
+      window.EVOLV.nodes.diffuser.assetMenu.saveEditor(this);
+    }
+    // Logger fields
+    if (window.EVOLV?.nodes?.diffuser?.loggerMenu?.saveEditor) {
+      window.EVOLV.nodes.diffuser.loggerMenu.saveEditor(this);
+    }
   },
 });
 </script>
@@ -40,8 +81,11 @@ RED.nodes.registerType('diffuser', {
     <input type="number" id="node-input-i_elements" min="1">
   </div>
   <div class="form-row">
-    <label for="node-input-i_diff_density"><i class="fa fa-braille"></i> Density %</label>
-    <input type="number" id="node-input-i_diff_density" step="0.1" min="0">
+    <label for="node-input-i_diff_density"><i class="fa fa-braille"></i> Bottom coverage [%]</label>
+    <input type="number" id="node-input-i_diff_density" step="0.1" min="0" max="100" placeholder="typical 10-25">
+    <div style="font-size:11px;color:#666;margin-left:160px;">
+      Fraction of tank floor occupied by diffuser membrane (%). Used as the curve-family key.
+    </div>
   </div>
   <div class="form-row">
     <label for="node-input-i_m_water"><i class="fa fa-arrows-v"></i> Water Height</label>
@@ -55,6 +99,7 @@ RED.nodes.registerType('diffuser', {
     <label for="node-input-i_zone_volume"><i class="fa fa-cube"></i> Zone Volume</label>
     <input type="number" id="node-input-i_zone_volume" step="0.1" min="0" placeholder="m3">
   </div>
+
   <h3>Output Formats</h3>
   <div class="form-row">
     <label for="node-input-processOutputFormat"><i class="fa fa-random"></i> Process Output</label>
@@ -72,21 +117,14 @@ RED.nodes.registerType('diffuser', {
       <option value="csv">csv</option>
     </select>
   </div>
-  <div class="form-row">
-    <label for="node-input-enableLog"><i class="fa fa-book"></i> Enable Log</label>
-    <input type="checkbox" id="node-input-enableLog" style="width: auto;">
-  </div>
-  <div class="form-row">
-    <label for="node-input-logLevel"><i class="fa fa-signal"></i> Log Level</label>
-    <select id="node-input-logLevel">
-      <option value="debug">debug</option>
-      <option value="info">info</option>
-      <option value="warn">warn</option>
-      <option value="error">error</option>
-    </select>
-  </div>
+
+  <!-- Asset fields injected here by the shared asset menu (supplier → type → model → unit) -->
+  <div id="asset-fields-placeholder"></div>
+
+  <!-- Logger fields injected here by the shared logger menu -->
+  <div id="logger-fields-placeholder"></div>
 </script>
 
 <script type="text/html" data-help-name="diffuser">
-  <p>Diffused aeration device model.</p>
+  <p>Diffused aeration device model. Resolves a supplier curve (SSOTR vs flow per element, DWP vs flow) at the configured bottom-coverage %, and emits the resulting oxygen-transfer rate plus a zone OTR for the parent reactor.</p>
 </script>

diffuser.js

@@ -1,9 +1,31 @@
 const nameOfNode = 'diffuser';
 const nodeClass = require('./src/nodeClass.js');
+const { MenuManager, configManager } = require('generalFunctions');
 
 module.exports = function(RED) {
   RED.nodes.registerType(nameOfNode, function(config) {
     RED.nodes.createNode(this, config);
     this.nodeClass = new nodeClass(config, RED, this, nameOfNode);
   });
+
+  const menuMgr = new MenuManager();
+  const cfgMgr  = new configManager();
+
+  RED.httpAdmin.get(`/${nameOfNode}/menu.js`, (req, res) => {
+    try {
+      const script = menuMgr.createEndpoint(nameOfNode, ['asset', 'logger']);
+      res.type('application/javascript').send(script);
+    } catch (err) {
+      res.status(500).send(`// Error generating menu: ${err.message}`);
+    }
+  });
+
+  RED.httpAdmin.get(`/${nameOfNode}/configData.js`, (req, res) => {
+    try {
+      const script = cfgMgr.createEndpoint(nameOfNode);
+      res.type('application/javascript').send(script);
+    } catch (err) {
+      res.status(500).send(`// Error generating configData: ${err.message}`);
+    }
+  });
 };

src/nodeClass.js

@@ -14,11 +14,19 @@ class nodeClass extends BaseNodeAdapter {
 
   buildDomainConfig(uiConfig) {
     const n = (v, fb) => (Number.isFinite(Number(v)) ? Number(v) : fb);
+    const s = (v, fb) => (typeof v === 'string' && v.length ? v : fb);
     return {
+      asset: {
+        model:          s(uiConfig.model, 'gva-elastox-r'),
+        assetTagNumber: s(uiConfig.assetTagNumber, ''),
+      },
+      general: {
+        unit:           s(uiConfig.unit, 'Nm3/h'),
+      },
       diffuser: {
         number:           n(uiConfig.number, 1),
         elements:         n(uiConfig.i_elements, 1),
-        density:          n(uiConfig.i_diff_density, 2.4),
+        density:          n(uiConfig.i_diff_density, 15),
         waterHeight:      n(uiConfig.i_m_water, 0),
         alfaFactor:       n(uiConfig.alfaf, 0.7),
         headerPressure:   n(uiConfig.i_pressure, 0),

src/specificClass.js

@@ -1,6 +1,12 @@
 'use strict';
 
-const { BaseDomain, statusBadge, interpolation, gravity, convert } = require('generalFunctions');
+const { BaseDomain, statusBadge, interpolation, gravity, convert, loadCurve } = require('generalFunctions');
+
+// Default curve used when the node's asset model field is not set. Preserves
+// the historical behaviour of the hardcoded _loadSpecs() (GVA ELASTOX-R at
+// density 2.4 elements/m²) — the existing test suite calibrates against
+// these numbers.
+const DEFAULT_DIFFUSER_MODEL = 'gva-elastox-r';
 
 class Diffuser extends BaseDomain {
   static name = 'diffuser';
@@ -19,7 +25,7 @@ class Diffuser extends BaseDomain {
     this.i_water_density = _num(d.waterDensity, 997);
     this.i_alfa_factor = _num(d.alfaFactor, 0.7);
     this.i_n_elements = _posInt(d.elements, 1);
-    this.i_diff_density = _num(d.density, 2.4);
+    this.i_diff_density = _num(d.density, 15);
     this.i_m_water = _num(d.waterHeight, 0);
     this.i_flow = 0;
     this.zoneVolume = _num(d.zoneVolume, 0);
@@ -219,11 +225,27 @@ class Diffuser extends BaseDomain {
   }
 
   _loadSpecs() {
+    // Curve lookup id: prefer the asset-menu-saved field, fall back to the
+    // legacy GVA ELASTOX-R reference (same numbers as the previous inline
+    // _loadSpecs). If a configured id misses the registry, fall back too —
+    // a missing curve would otherwise crash the constructor in production.
+    const cfgModel =
+      this.config?.asset?.model ||
+      this.config?.model ||
+      DEFAULT_DIFFUSER_MODEL;
+    const raw = loadCurve(cfgModel) || loadCurve(DEFAULT_DIFFUSER_MODEL);
+    if (!raw || !raw.otr_curve || !raw.p_curve) {
+      throw new Error(
+        `diffuser: curve '${cfgModel}' is missing otr_curve/p_curve (registry has: ${Object.keys(raw || {}).join(',') || 'nothing'})`,
+      );
+    }
     return {
-      supplier: 'GVA', type: 'ELASTOX-R',
+      supplier: raw._meta?.supplier || null,
+      type: raw._meta?.type || null,
+      model: raw._meta?.model || cfgModel,
       units: { Nm3: { temp: 20, pressure: 1.01325, RH: 0 } },
-      otr_curve: { 2.4: { x: [2, 3, 4, 5, 6, 7, 8, 9, 10],     y: [26, 25, 24, 23.5, 23, 22.75, 22.5, 22.25, 22] } },
-      p_curve:   { 0:   { x: [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12], y: [40, 42.5, 45, 47.5, 50, 51.5, 53, 54.5, 56, 57.5, 59] } },
+      otr_curve: raw.otr_curve,
+      p_curve: raw.p_curve,
     };
   }
 }