Worked on the microsoft/playwright repository to enhance test reliability by addressing a subtle issue in fixture management. Focused on fixing the handling of fixtures named "then," which were incorrectly treated as thenable promises, the solution involved wrapping fixture parameters in an object within the FixtureRunner and updating WorkerMain to extract these parameters correctly. This change, implemented in TypeScript, was accompanied by new regression tests to ensure the fix remained robust and prevented future regressions. The work improved the stability of Playwright’s continuous integration pipeline, reduced test flakiness, and contributed to more predictable and efficient feature development cycles.