Worked on the vercel/ai repository to enhance token cost visibility and citation reliability within AI-powered chat and search features. Developed a TypeScript-based solution that tracks token usage in the useChat onFinish callback, allowing users to monitor input, output, and total tokens directly in the UI. Improved inline citation handling by supporting web_search_result_location citations and ensuring accurate tracking of webFetch documents, which resolved issues with dropped citations. Emphasized robust API development and integration, incorporating runtime validation with Zod schemas and comprehensive testing. These updates improved cost transparency, citation accuracy, and overall SDK reliability for developers building chat and web integrations.