A collaboration session is provided in which an owner computer system and a participant computer system are both members. Within this collaboration session, both the owner and the participant computer systems are provided access to a multi-file workspace's build instance. Here, the multi-file workspace and the build instance are both stored locally on the owner computer system. Further, this workspace includes multiple files of source code. As a result, the build instance is a build of that source code. Various debug commands that are directed to the build instance may be received. Some of these commands originate from the owner computer system while others originate from the participant computer system. These debug commands are then multiplexed, and the build instance is executed in accordance with the multiplexed debug commands. As a result of executing the build instance, debugging data is generated.