The AI SDK splits an AI message into a parts array — text, reasoning, source-url, tool-* — each an independent typed fragment (introduced in v5, unchanged since). That data structure dictates how modern AI conversation UIs are written: render by switching on part.type, handing each fragment to its component. This post unpacks the design logic of the parts model, useChat's streaming behavior, and how it became the foundation for component libraries like AI Elements.
AI Elements is Vercel's React component library for the AI SDK ecosystem — the registry currently holds 48 components covering Conversation, Reasoning, Sources, Tool, and the rest of the AI-interface vocabulary. It follows the shadcn model: npx ai-elements@latest copies the source into your project, fully editable, mapped one-to-one onto useChat's message parts.
A comparison of seven major design systems—Tailwind, Radix, Material 3, Carbon, Ant Design, Primer, and Apple HIG—covering scale structure, neutral colors, dark-mode strategies, and why new projects should prefer OKLCH over HSL.
shadcn/ui is not an npm package — it copies component source code directly into your project, giving you full ownership. DaoDao uses it to build packages/ui, a shared component library used across three Next.js apps.
Tamagui is a UI framework built for React Native with a complete design token system, theme support, and compile-time optimization that moves style computation to build time. NobodyClimb chose it over NativeWind primarily because its cross-platform token system is more robust.