A user interface is configured to present a stream of activities that arise from operation of two or more heterogeneous applications that access shared content objects of a content management system. A first application of a first type among the heterogeneous applications interoperates with a second application of a second type. Application activity records that correspond to interactions by the second application over the shared content objects are stored. Additional interactions that are raised by the first application and that pertain to a common content object are also stored. When a user requests access to a content object of the content management system, recent application activity records are selected. Some of the selected activity records are filtered out based on permissions attributes corresponding to the content object and/or based on permissions attributes corresponding to the requesting user. An application activity stream is generated based on the selected application activity records.