toServerSentEventsResponse

function toServerSentEventsResponse<TOffset>(stream, init?): Response;

Defined in: packages/ai/src/stream-to-response.ts:1059

Convert a StreamChunk async iterable to a Response in Server-Sent Events format

This creates a Response that emits chunks in SSE format:

• Each chunk is prefixed with "data: "
• Each chunk is followed by "\n\n"
• Stream ends when the underlying iterable is exhausted (RUN_FINISHED is the terminal event)

Pass a durability sink (memoryStream(request) / durableStream(request)) to make the stream resumable: fresh runs are appended to the log and each SSE event is tagged with an id: offset; a reconnect (native Last-Event-ID) or a ?offset join replays from the log without re-running the producer. batch controls how many chunks are buffered per append (default 32), and batchWaitMs how long a buffered chunk waits for more (default 50).

Type Parameters

TOffset

TOffset extends string = string

Parameters

stream

AsyncIterable<AGUIEvent>

AsyncIterable of StreamChunks from chat()

init?

ResponseInit & object

Optional Response initialization options (including abortController, durability with its optional batch and batchWaitMs, and debug)

Returns

Response

Response in Server-Sent Events format

Example

export async function POST(request: Request) {
  const stream = chat({ adapter: openaiText('gpt-5.5'), messages: [...] });
  return toServerSentEventsResponse(stream, { durability: { adapter: memoryStream(request) } });
}