Ben Standefer developed multi-value response headers support for serverless functions in the netlify/primitives repository, focusing on accurate header preservation and reconstruction in API responses. He implemented this feature using TypeScript, leveraging his skills in API development and serverless functions to ensure both standard and multiValueHeaders were correctly merged and propagated, including in the Vite plugin development workflow. Ben also streamlined the codebase by removing an unused header conversion helper, reducing technical debt. To maintain reliability, he added regression tests for both plain and streamed responses, validating header handling across environments and addressing a dev-time header propagation issue.