Add a setData Function to useCompletion

[marnelram]

Feature Description

The useCompletion hook currently provides access to provider metadata by streaming it through the data field and onMessageAnnotation callback, but doesn't allow the data to be modified on the front-end. This feature would allow the data to be cleared if the user makes another completion request.

An example implementation:

  const {
    completion: researchOutput,
    data: citations,
    setData: setCitations,
    complete: research,
    isLoading: isResearching,
  } = useCompletion({
    api: "/api/perplexityTest"
  });

Use Cases

Use Case

1. Clean State Between Completions

   • Clearing accumulated metadata before starting new completions
   • Resetting citation lists for new research queries
   • Ensuring stale data doesn't persist between different user sessions

2. Error Recovery

   • Clearing invalid or partial data after failed completions
   • Resetting to a known state when handling errors

Additional context

Current Workaround is setting citations in a separate state variable

const [citations, setCitations] = useState<string[] | undefined>(undefined);
  const {
    completion: researchOutput,
    data: researchData,
    complete: research,
    isLoading: isResearching,
  } = useCompletion({
    api: "/api/perplexityTest",
    onFinish: (completion) => {
      setCitations(researchData as string[]);
    },
  });