A server system having memory and one or more processors running a trusted internal process receives, from an untrusted external process of one or more external processes, a request to interact with a data item. In response to the request, the server system interacts with the first data item and stores a marker indicative of the interaction with the data item. After storing the marker, the server system identifies a plurality of markers corresponding to a plurality of data items and retrieves information corresponding to the plurality of markers. The retrieved information enables a determination, for each data item in the plurality of data items, as to whether an operation corresponding to the data item is to be executed. When a determination has been made that an operation corresponding to the data item is to be executed, the server system deletes the markers in conjunction with execution of the operation.