Worked on enhancing the reliability of GraphQL subscriptions in the microsoft/graphitation repository by implementing comprehensive end-to-end testing for error handling during mid-stream events. Focused on improving type safety within the GraphQL schema by refactoring resolver definitions using TypeScript, which helps prevent silent failures and increases maintainability. Introduced snapshot testing to ensure that future changes do not introduce regressions, and updated test execution logic to cover scenarios where errors occur during active subscriptions. This work leveraged skills in GraphQL subscriptions, schema definition, and testing, resulting in a more robust and predictable GraphQL layer for ongoing development and maintenance.