A stop generation button is available during generation

Without a stop button the user is held hostage by every generation they regret starting: a prompt that is clearly going off the rails, a response already too long, a hallucination cascading into more hallucinations. They cannot terminate the stream, cannot re-prompt, and the product burns their tokens and wall-clock time on output they will immediately delete. This is one of the most-cited usability gaps in AI chat products and directly affects token-spend efficiency for paying users.

In src/components/chat/ChatInput.tsx, swap the Send button for a Stop button while isLoading is true and wire it to the stop() function from useChat (or to controller.abort() for custom AbortController-based fetches). The partial response should remain visible after stopping.

{isLoading ? (
  <Button onClick={stop} variant="destructive">Stop</Button>
) : (
  <Button type="submit">Send</Button>
)}