Worked on the Shopify/cli repository to enhance the Theme Development Proxy by improving the handling of Authorization headers. Addressed a security concern by ensuring Bearer tokens were excluded from cart, checkout, and account proxy endpoints, which reduced unauthorized token usage and API errors. Expanded unit test coverage using Jest to validate authentication header behavior, including edge cases involving query strings and non-CDN authentication paths. Applied Prettier formatting and related code quality improvements to maintain consistency across the Node.js and TypeScript codebase. These changes increased the security and reliability of storefront proxy flows, supporting smoother theme development workflows for developers.