Ai sdk Interview Questions

useChat keeps an array of UIMessage objects, each with an id, a role and a list of parts. sendMessage adds your message right away, sets status to submitted, posts the conversation through a transport and then applies each streamed chunk to the assistant message, moving status to streaming and finally to ready or error. Helpers like stop, regenerate and setMessages change that same array, and the throttle option limits how often React re-renders.

The server owns everything that must be trusted: the API key, the model choice, the system instructions, tool execution, auth, input validation, rate limits and saving the conversation. The client owns everything the user touches: the input box, the message list, rendering streamed parts, the stop button and loading or error states. In the App Router that usually means a Route Handler that returns a UI message stream and a Client Component that uses useChat.

An AI SDK gives you one API (generateText, streamText, tools, structured output and a UI message stream) on top of a shared language model specification, so switching providers is mostly a change to the model argument. What stays provider-specific is capability and behaviour: which models support tools, images or reasoning, how they tokenize and price, features like prompt caching, and extra settings you pass through providerOptions keyed by provider name.