During June 2025, Korri focused on improving historical date handling in the formatjs/formatjs repository. They addressed a longstanding issue where JavaScript’s Date.UTC function incorrectly parsed years before 100 AD, leading to inaccurate day calculations. By introducing conditional logic in TypeScript, Korri ensured that the DayFromYear function now correctly processes dates prior to 100 AD, aligning with ECMA-402 standards. They also developed targeted tests to validate these changes and prevent future regressions. This work enhanced the reliability of internationalization features, particularly for edge-case date formatting, and demonstrated a strong grasp of date handling and JavaScript internals in production code.