diff --git a/src/server/routes/adminModels.ts b/src/server/routes/adminModels.ts
index ec85461..c8245af 100644
--- a/src/server/routes/adminModels.ts
+++ b/src/server/routes/adminModels.ts
@@ -242,10 +242,15 @@ router.get('/admin/models/:id/edit', requireAdmin, (req: Request, res: Response)
   const model = q<Model>(`SELECT * FROM models WHERE id = ?`).get(req.params.id)
   if (!model) { res.redirect('/admin'); return }
 
-  const categories = q<Category>(`SELECT * FROM categories ORDER BY sort_order, name`).all()
-  const pdfs       = q<ModelPdf>(`SELECT * FROM model_pdfs WHERE model_id = ? ORDER BY sort_order`).all(model.id)
+  const categories  = q<Category>(`SELECT * FROM categories ORDER BY sort_order, name`).all()
+  const pdfs        = q<ModelPdf>(`SELECT * FROM model_pdfs WHERE model_id = ? ORDER BY sort_order`).all(model.id)
+  const absModelPath = path.join(UPLOADS_DIR, model.file_path)
+  const hasGeometry = (model.file_type === 'step' || model.file_type === 'stp')
+    ? fs.existsSync(geometryOutputPath(absModelPath))
+    : true
+
   res.render('admin/edit', {
-    model, categories, pdfs, error: null,
+    model, categories, pdfs, error: null, hasGeometry,
     baseUrl: process.env.BASE_URL ?? `http://localhost:${process.env.PORT ?? 3000}`,
   })
 })
@@ -277,6 +282,44 @@ router.post('/admin/pdfs/:id/delete', requireAdmin, (req: Request, res: Response
   res.redirect(`/admin/models/${pdf.model_id}/edit`)
 })
 
+// ---- Reconvert STEP/STP geometry -----------------------------------------
+
+router.post('/admin/models/:id/reconvert', requireAdmin, async (req: Request, res: Response) => {
+  const model = q<Model>(`SELECT * FROM models WHERE id = ?`).get(req.params.id)
+  if (!model) { res.status(404).json({ error: 'Model not found' }); return }
+
+  if (model.file_type !== 'step' && model.file_type !== 'stp') {
+    res.status(400).json({ error: 'Only STEP/STP models require geometry conversion' }); return
+  }
+
+  const absModelPath = path.join(UPLOADS_DIR, model.file_path)
+  if (!fs.existsSync(absModelPath)) {
+    res.status(404).json({ error: 'Source model file not found on disk' }); return
+  }
+
+  const geoOutPath = geometryOutputPath(absModelPath)
+
+  try {
+    await convertStepFile(absModelPath, geoOutPath)
+  } catch (err) {
+    res.status(500).json({ error: `Conversion failed: ${(err as Error).message}` }); return
+  }
+
+  // Regenerate thumbnail from new geometry (non-fatal)
+  try {
+    const geo  = JSON.parse(fs.readFileSync(geoOutPath, 'utf8')) as GeometryFile
+    const tris = geometryToTriangles(geo)
+    const thumbPath = thumbnailOutputPath(UPLOADS_DIR, model.id)
+    await renderThumbnail(tris, thumbPath)
+    const thumbRel = path.relative(UPLOADS_DIR, thumbPath).replace(/\\/g, '/')
+    db.prepare(`UPDATE models SET thumbnail_path = ? WHERE id = ?`).run(thumbRel, model.id)
+  } catch (thumbErr) {
+    console.error('[thumbnail] reconvert thumbnail failed:', (thumbErr as Error).message)
+  }
+
+  res.json({ ok: true })
+})
+
 // ---- JSON list -----------------------------------------------------------
 
 router.get('/api/admin/models', requireAdmin, (_req: Request, res: Response) => {
diff --git a/src/server/services/stepConverter.ts b/src/server/services/stepConverter.ts
index 969cbfe..40347fc 100644
--- a/src/server/services/stepConverter.ts
+++ b/src/server/services/stepConverter.ts
@@ -22,7 +22,11 @@ let _init: Promise<Awaited<ReturnType<typeof occtimport>>> | null = null
 
 async function getOcct() {
   if (_occt) return _occt
-  if (!_init) _init = occtimport().then(m => { _occt = m; return m })
+  if (!_init) {
+    _init = occtimport().then(m => { _occt = m; return m })
+    // Reset on failure so the next upload attempt retries rather than replaying a cached rejection
+    _init.catch(() => { _init = null })
+  }
   return _init
 }
 
diff --git a/views/admin/edit.ejs b/views/admin/edit.ejs
index f98f02c..32b0773 100644
--- a/views/admin/edit.ejs
+++ b/views/admin/edit.ejs
@@ -61,6 +61,31 @@
       </div>
     </form>
 
+    <!-- Geometry status (STEP/STP only) -->
+    <% if (model.file_type === 'step' || model.file_type === 'stp') { %>
+    <div class="bg-surface-900 border border-gray-800 rounded-2xl p-6 mb-6">
+      <h2 class="text-sm font-semibold text-white mb-3">3D Geometry Processing</h2>
+      <% if (hasGeometry) { %>
+      <div class="flex items-center gap-2 text-sm text-green-400">
+        <svg class="w-4 h-4 shrink-0" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg>
+        Geometry processed successfully
+      </div>
+      <% } else { %>
+      <div class="flex items-center justify-between gap-4">
+        <div class="flex items-center gap-2 text-sm text-amber-400">
+          <svg class="w-4 h-4 shrink-0" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2"><path stroke-linecap="round" stroke-linejoin="round" d="M12 9v4m0 4h.01M10.29 3.86L1.82 18a2 2 0 001.71 3h16.94a2 2 0 001.71-3L13.71 3.86a2 2 0 00-3.42 0z"/></svg>
+          Geometry processing failed — model cannot be viewed
+        </div>
+        <button type="button" id="reconvert-btn"
+          class="shrink-0 bg-surface-700 hover:bg-surface-600 border border-gray-700 text-sm text-gray-300 rounded-lg px-4 py-2 transition-colors">
+          Retry Processing
+        </button>
+      </div>
+      <pre id="reconvert-error" class="mt-3 text-xs text-red-400 whitespace-pre-wrap break-all hidden"></pre>
+      <% } %>
+    </div>
+    <% } %>
+
     <!-- Attached PDFs -->
     <div class="bg-surface-900 border border-gray-800 rounded-2xl p-6 mb-6">
       <h2 class="text-sm font-semibold text-white mb-4">Shop Diagrams / PDFs</h2>
@@ -115,5 +140,34 @@
 </div>
 
 <script src="/admin.js"></script>
+<script>
+(function () {
+  const btn = document.getElementById('reconvert-btn')
+  if (!btn) return
+  const errEl = document.getElementById('reconvert-error')
+  btn.addEventListener('click', async () => {
+    btn.disabled = true
+    btn.textContent = 'Processing…'
+    errEl.classList.add('hidden')
+    try {
+      const res  = await fetch('/admin/models/<%= model.id %>/reconvert', { method: 'POST' })
+      const data = await res.json()
+      if (data.ok) {
+        window.location.reload()
+      } else {
+        errEl.textContent = data.error ?? 'Unknown error'
+        errEl.classList.remove('hidden')
+        btn.disabled = false
+        btn.textContent = 'Retry Processing'
+      }
+    } catch (err) {
+      errEl.textContent = String(err)
+      errEl.classList.remove('hidden')
+      btn.disabled = false
+      btn.textContent = 'Retry Processing'
+    }
+  })
+})()
+</script>
 </body>
 </html>