Worked on the great-expectations/great_expectations repository to improve the reliability of parameterized data validation. Focused on hardening the ExpectTableRowCountToBeBetween expectation by fixing its runtime parameter handling, specifically ensuring that dictionary inputs for min_value and max_value correctly require the '$PARAMETER' key. Addressed a bug where the expectation failed validation with certain runtime parameters, and expanded unit test coverage to include both valid and invalid configurations. Utilized Python for implementation, emphasizing robust bug fixing, data validation, and comprehensive testing practices. The work reduced production risk by making parameterized validations more predictable and easier to maintain within the codebase.