Over a two-month period, contributed to MetaMask/core by developing the MultichainNetworkController, enabling seamless network and account switching across both EVM and non-EVM chains. This work involved refactoring existing switching logic and updating dependent controllers to support a unified multichain user experience, laying the groundwork for scalable cross-chain support. Leveraging TypeScript, JavaScript, and Node.js, the implementation focused on maintainable architecture and improved user workflows. Additionally, addressed CI reliability in MetaMask/github-tools by updating the GitHub Actions Xcode version, resolving Swift module compilation errors and enhancing developer feedback. The work demonstrated depth in full stack development, CI/CD, and controller design.