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>