diff --git a/__init__.py b/__init__.py
index b498e1d4..d6e0df3d 100644
--- a/__init__.py
+++ b/__init__.py
@@ -52,8 +52,47 @@ def _register_gpack_routes():
         items.sort()
         return web.json_response(items)
 
+    # /gpack/save_preview -- the viewers' "Save mesh" button. Copies a temp
+    # preview export (preview_*.stl/vtp/glb, written to ComfyUI output/ or the
+    # OS tempdir by the preview nodes) to a stable name in output/ so it
+    # survives the next preview run. Body: {"temp_filename": "<basename>"}.
+    @inst.routes.post("/gpack/save_preview")
+    async def _gpack_save_preview(request):
+        import shutil
+        try:
+            body = await request.json()
+        except Exception:
+            return web.json_response({"success": False, "error": "invalid JSON body"}, status=400)
+        # basename() defuses path traversal -- we only ever serve files the
+        # preview nodes themselves wrote into these two directories.
+        name = os.path.basename(str(body.get("temp_filename") or ""))
+        if not name:
+            return web.json_response({"success": False, "error": "temp_filename required"}, status=400)
+        import tempfile
+        try:
+            import folder_paths
+            out_dir = folder_paths.get_output_directory()
+        except Exception:
+            out_dir = None
+        candidates = [d for d in (out_dir, tempfile.gettempdir()) if d]
+        src = next((os.path.join(d, name) for d in candidates
+                    if os.path.isfile(os.path.join(d, name))), None)
+        if src is None:
+            return web.json_response(
+                {"success": False, "error": f"{name} not found (previews are temporary; re-run the node)"},
+                status=404)
+        if out_dir is None:
+            return web.json_response({"success": False, "error": "no ComfyUI output directory"}, status=500)
+        saved = f"saved_{name}"
+        try:
+            shutil.copy2(src, os.path.join(out_dir, saved))
+        except OSError as e:
+            return web.json_response({"success": False, "error": str(e)}, status=500)
+        log.info("[GeomPack] saved preview %s -> %s", name, saved)
+        return web.json_response({"success": True, "saved_filename": saved})
+
     inst._gpack_getpath_registered = True
-    log.info("[GeomPack] /gpack/getpath route registered")
+    log.info("[GeomPack] /gpack/getpath + /gpack/save_preview routes registered")
 
 
 try:
diff --git a/javascript/js/mesh_preview_multi.js b/javascript/js/mesh_preview_multi.js
index a3a3eb96..2ae24a46 100644
--- a/javascript/js/mesh_preview_multi.js
+++ b/javascript/js/mesh_preview_multi.js
@@ -181,13 +181,27 @@ app.registerExtension({
                     iframe.src = `/extensions/${EXTENSION_FOLDER}/${viewerUrl()}?v=` + Date.now();
                 });
 
-                const onDim = () => {
-                    viewerState.grid_cols = colsInput.value ? Math.max(1, parseInt(colsInput.value, 10)) : null;
-                    viewerState.grid_rows = rowsInput.value ? Math.max(1, parseInt(rowsInput.value, 10)) : null;
+                // The edited field is authoritative; the OTHER dimension auto-raises
+                // so cols*rows always fits every mesh. Without this, a grid smaller
+                // than the mesh count overflows into implicit CSS rows (auto height)
+                // and the layout stops matching the inputs. Both inputs are updated
+                // so the UI always shows the grid actually in effect.
+                const onDim = (edited) => () => {
+                    const n = lastLoad?.numMeshes || 1;
+                    let cols = Math.max(1, parseInt(colsInput.value, 10) || 0) || (lastLoad?.autoCols ?? 1);
+                    let rows = Math.max(1, parseInt(rowsInput.value, 10) || 0) || (lastLoad?.autoRows ?? 1);
+                    if (cols * rows < n) {
+                        if (edited === "cols") rows = Math.ceil(n / cols);
+                        else cols = Math.ceil(n / rows);
+                    }
+                    colsInput.value = cols;
+                    rowsInput.value = rows;
+                    viewerState.grid_cols = cols;
+                    viewerState.grid_rows = rows;
                     buildAndSend();   // same iframe -> viewer re-tiles, no reload
                 };
-                colsInput.addEventListener('change', onDim);
-                rowsInput.addEventListener('change', onDim);
+                colsInput.addEventListener('change', onDim("cols"));
+                rowsInput.addEventListener('change', onDim("rows"));
 
                 syncLayoutUI();
                 applyCollapsed();
diff --git a/javascript/viewer_vtk.html b/javascript/viewer_vtk.html
index 99f124e6..07826049 100644
--- a/javascript/viewer_vtk.html
+++ b/javascript/viewer_vtk.html
@@ -1031,7 +1031,7 @@
                 saveButton.disabled = true;
                 saveButton.textContent = 'Saving...';
 
-                const response = await fetch('/geometrypack/save_preview', {
+                const response = await fetch('/gpack/save_preview', {
                     method: 'POST',
                     headers: { 'Content-Type': 'application/json' },
                     body: JSON.stringify({ temp_filename: currentFilename })