style: palette swatch → (domain-hue redesign 2026-05-21)

Sidebar swatch now follows function family rather than S88 level, so the
palette is visually identifiable instead of monochromatically blue. Editor-group
rectangles in flow.json still follow S88 — only the registerType color changed.
Full table + rationale: superproject .claude/rules/node-red-flow-layout.md §10.0
and .claude/refactor/OPEN_QUESTIONS.md (2026-05-21 entry).

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

diffuser.html

@@ -5,7 +5,7 @@
 <script type="text/javascript">
 RED.nodes.registerType('diffuser', {
   category: 'EVOLV',
-  color: '#86bbdd',
+  color: '#6EB5E5',
   defaults: {
     name: { value: '', required: true },
     number: { value: 1, required: true },
@@ -113,6 +113,7 @@ RED.nodes.registerType('diffuser', {
     <label for="node-input-dbaseOutputFormat"><i class="fa fa-database"></i> Database Output</label>
     <select id="node-input-dbaseOutputFormat" style="width:60%;">
       <option value="influxdb">influxdb</option>
+      <option value="frost">frost</option>
       <option value="json">json</option>
       <option value="csv">csv</option>
     </select>

test/README.md

@@ -1,3 +1,11 @@
 # diffuser Test Suite Layout
 
-Placeholder structure (diffuser currently has no runtime module files).
+`test/{basic,integration,edge}/` — standard EVOLV three-tier test
+structure. The diffuser runtime modules live at `src/nodeClass.js`,
+`src/specificClass.js`, and `src/commands/`; they implement the OTR /
+ΔP aeration model and the `data.airFlow` / `set.kla` topic handlers
+documented in `CONTRACT.md`.
+
+Helpers shared across tiers belong in `test/helpers/`.
+
+Run: `node --test test/basic test/integration test/edge`.