Marvin Kastner focused on enhancing user guidance and onboarding for constrained optimization workflows in the optuna/optuna repository by updating documentation to include GPSampler as a supported sampler. He integrated GPSampler into the main documentation and FAQ, providing clear references to multi-objective optimization with constraints using NSGAIISampler. Working primarily with reStructuredText and leveraging his documentation skills, Marvin ensured that the new feature was traceable by linking the relevant commit. His work improved clarity for users adopting GPSampler, reducing support queries and onboarding time. The depth of the update was limited to documentation, with no direct code or bug fixes during this period.