Worked on stabilizing the google/j2cl test suite by addressing a cross-environment incompatibility in October 2024. Identified that the testSetValueWriteThrough test exhibited inconsistent behavior due to differences in MutableMap.Entry implementations, particularly affecting the J2kt environment. Rather than modifying production code, introduced a targeted compatibility flag at the test level, marking the test as J2ktIncompatible. This approach preserved the integrity of functional code while ensuring reliable and accurate test results across environments. Utilized Java and compatibility engineering skills, with a focus on robust testing practices, resulting in reduced CI noise, faster developer feedback, and clearer ownership of environment-specific test cases.