Update app.py

app.py

@@ -2298,13 +2298,13 @@ def download_sb3(project_id):
 @app.route("/download_pdf/<project_id>", methods=["GET"])
 def download_pdf(project_id):
     pdf_path = GEN_PROJECT_DIR / f"{project_id}.pdf"
-    if not pdf_doc.exists():
+    if not pdf_path.exists():
         return jsonify({"error": "Scratch project file not found"}), 404
 
     return send_file(
-        pdf_doc,
+        pdf_path,
         as_attachment=True,
-        download_name=pdf_doc.name
+        download_name=pdf_path.name
     )
 
 # API endpoint