Significant work done porting to headless engine

procedural/src/engine/support/routes-generator_render.md

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+# Removed Rendering/UI Logic from routes-generator.js
+
+The following DOM manipulation and SVG rendering code blocks were **removed** from the engine module and should be moved to the Viewer application:
+
+## 1. Route Path Generation (SVG)
+**Location:** `getPath()` function (lines 675-680)
+```javascript
+const ROUTE_CURVES = {
+  roads: d3.curveCatmullRom.alpha(0.1),
+  trails: d3.curveCatmullRom.alpha(0.1),
+  searoutes: d3.curveCatmullRom.alpha(0.5),
+  default: d3.curveCatmullRom.alpha(0.1)
+};
+
+function getPath({group, points}) {
+  const lineGen = d3.line();
+  lineGen.curve(ROUTE_CURVES[group] || ROUTE_CURVES.default);
+  const path = round(lineGen(points.map(p => [p[0], p[1]])), 1);
+  return path;
+}
+```
+
+## 2. Route Length Measurement (DOM Access)
+**Location:** `getLength()` function (lines 682-685)
+```javascript
+function getLength(routeId) {
+  const path = routes.select("#route" + routeId).node();
+  return path.getTotalLength();
+}
+```
+
+## 3. Route Removal from SVG (DOM Manipulation)
+**Location:** `remove()` function (line 707)
+```javascript
+// From the original remove() function:
+viewbox.select("#route" + route.i).remove();
+```
+
+## 4. Console Timing (UI Feedback)
+**Location:** Throughout generation functions
+```javascript
+// Lines 121, 139, 144, 162, 167, 185
+TIME && console.time("generateMainRoads");
+TIME && console.timeEnd("generateMainRoads");
+TIME && console.time("generateTrails");
+TIME && console.timeEnd("generateTrails");
+TIME && console.time("generateSeaRoutes");
+TIME && console.timeEnd("generateSeaRoutes");
+```
+
+## Summary
+- **SVG path generation using D3** - Should be handled by the Viewer
+- **DOM element selection and manipulation** - Should be handled by the Viewer
+- **Console timing output** - Should be handled by the Viewer for debugging
+- **Direct access to SVG elements** - Should be handled by the Viewer
+
+The engine now returns pure data that the Viewer can use to create SVG paths and handle all rendering operations.