Enigma is originally authored by cuchaz; FabricMC has maintained a fork of it since 2016, and has since been using it for yarn development.
See enigma documentation.
Graphical User Interface
Open enigma jar by double clicking it. In the file menu, select “open jar” to choose the jar to map; then select “open mappings” to select the mappings to continue working on (or just start mapping if you are starting fresh).
When you want to save your work, you can go to save option in the file menu and save your mappings.
Certain features of enigma, such as custom services, profiles, etc. are only available through command line. Hence, yarn's enigma can only be launched properly from the gradle task because of its usage of advanced features.