Worked on the Shopify/tapioca repository to enhance GraphQL schema correctness by enforcing non-nullability for required mutation arguments. Addressed a bug where required fields could be incorrectly treated as nullable, updating the GraphQL type helper in Ruby on Rails to ensure type-safety. Expanded test coverage to validate non-null semantics across mutation inputs, and improved RBI generation so that required fields are accurately reflected as non-nullable. Included documentation clarifications and explanatory comments to support future maintenance. The work focused on backend development using Ruby and GraphQL, reducing the risk of runtime errors related to null values in mutation arguments.