{"message":"Spreadsheet Service","endpoints":{"upload":"POST /upload","upload_progress_webhook":"POST /upload-progress  (internal — called by worker)","upload_result":"GET /upload-result/{job_id}","upload_ws":"WS /ws/upload/{job_id}","status":"GET /status/{job_id}","transform":"POST /transform","transform_ws":"WS /ws/transform/{task_id}","transform_result":"GET /transform-result/{task_id}","transform_status":"GET /transform-status/{task_id}  (no cell data)","undo":"POST /undo/{spreadsheet_id}","redo":"POST /redo/{spreadsheet_id}","version_info":"GET /version/{spreadsheet_id}"}}