Worked on stabilizing the test infrastructure for the com-lihaoyi/mill repository by addressing a recurring issue in cross-version testing. Focused on build tool development using Scala, the work involved correcting the test source path in CrossSbtTests to ensure that test-specific Scala versions were properly identified and processed. This adjustment resolved persistent test compilation failures and reduced CI flakiness, improving reliability for cross-version scenarios. The solution enhanced diagnostics and traceability around versioned source handling, supporting more robust feedback cycles. Through targeted debugging and careful source management, contributed to a more dependable build and test process within the Mill project’s codebase.