model tree fix 2

src/client/viewer/main.ts

@@ -286,12 +286,32 @@ async function loadStepGeometry(): Promise<void> {
   fitCamera(group)
   addGrid(group)
 
+  // Diagnostics — always log tree state so browser console can confirm what arrived
+  console.log('[StepView] geometry version:', data.version)
+  console.log('[StepView] mesh count:', data.meshes.length)
+  console.log('[StepView] data.tree:', data.tree)
+
   const treeContent = document.getElementById('tree-content')
-  if (data.tree) {
-    wireTreePanel(data.tree)
-  } else if (treeContent) {
-    treeContent.innerHTML = '<p class="text-xs text-gray-500 px-4 py-3">Tree unavailable — reconvert this model in the admin panel to enable.</p>'
+  if (!treeContent) return   // not a STEP model or panel removed
+
+  if (!data.tree) {
+    treeContent.innerHTML = '<p class="text-xs text-gray-500 px-4 py-3">No tree data — open the admin panel, edit this model, and click <strong class="text-gray-400">Retry Processing</strong> to rebuild geometry with tree support.</p>'
+    return
   }
+
+  const nodeCount = countNodes(data.tree)
+  console.log('[StepView] tree node count:', nodeCount)
+
+  if (nodeCount === 0) {
+    treeContent.innerHTML = '<p class="text-xs text-gray-500 px-4 py-3">This file has no named components in its hierarchy.</p>'
+    return
+  }
+
+  wireTreePanel(data.tree)
+}
+
+function countNodes(node: HierarchyNode): number {
+  return 1 + node.children.reduce((acc, c) => acc + countNodes(c), 0)
 }
 
 // ---- STL loader (client-side, Three.js built-in) -------------------------