Fix project reopen persistence

backend/routed_layout_preview.py

@@ -9,6 +9,7 @@ import tempfile
 
 import yaml
 
+from layout_files import load_layout_cell_files, write_layout_cells_to_directory
 from router_dependency import require_router_stack
 
 
@@ -32,9 +33,20 @@ def create_routed_layout_svg(
     # Build into a temporary GDS first, then convert the generated top cell into
     # the SVG preview consumed by the canvas.
     with tempfile.TemporaryDirectory(prefix="mxpic_routed_preview_") as temp_dir:
+        staged_project_dir = os.path.join(temp_dir, "project")
+        saved_cells, _warnings = load_layout_cell_files(project_dir)
+        staged_cells = [cell for cell in saved_cells if cell["name"] != cell_name]
+        staged_cells.append({
+            "filename": f"{cell_name}.yml",
+            "name": cell_name,
+            "data": layout,
+            "content": yaml_content,
+        })
+        write_layout_cells_to_directory(staged_cells, staged_project_dir)
+
         temp_gds = os.path.join(temp_dir, f"{cell_name}.gds")
         build_project_gds(
-            project_dir=project_dir,
+            project_dir=staged_project_dir,
             output_path=temp_gds,
             pdk_root=pdk_root,
             technology_manifest_path=technology_manifest_path,