Worked on modernizing notebook metadata handling in the dotnet/interactive repository by removing the legacy 'custom' property and refactoring utilities to standardize on the 'metadata' field for polyglot notebook information. This update, implemented using TypeScript and JavaScript, simplified metadata management and reduced technical debt, making future enhancements more straightforward. The approach improved interoperability across different kernels by aligning with current standards for notebook metadata. No major bugs were addressed during this period, with the focus remaining on feature development. The work demonstrates a methodical approach to codebase modernization and maintenance, particularly in the context of VS Code extension development and notebooks.