Worked on the getsentry/sentry-python repository to stabilize the ARQ worker creation API by addressing a bug in how settings_cls was handled during worker instantiation. Improved the backend logic to ensure settings_cls could be passed as either a positional or keyword argument, preventing potential IndexError exceptions and enhancing API compatibility. Expanded the automated test suite using Python to cover these scenarios, specifically targeting kwarg-based usage to guard against future regressions. Focused on backend development and testing, the work delivered a robust fix that improved reliability for user workflows and maintained high code quality through comprehensive test coverage and careful attention to edge cases.