APIs Last update: 19.06.2026 The main interfaces a plug-in must implement: IHarnessRunner IHarnessBuilderUI<RUNNER> However, for the BuilderUI most plug-in writers will prefer to extend one of the abstract base class helpers in this SDK: AbstractVariableBasedBuilderUI<RUNNER> AbstractScriptBasedBuilderUI<RUNNER, MODEL> Here is a class diagram of the interfaces and abstract base classes relevant for a plug-in developer: