Function convertToStreamingResponseChunks

test/harness/replayingCapiProxy.ts:1411–1472

(
  completion: ChatCompletion,
)

const STREAM_CHUNK_SIZE = 200;

function convertToStreamingResponseChunks(
  completion: ChatCompletion,
): ChatCompletionChunk[] {
  const choice = completion.choices[0];
  const content = choice.message.content ?? "";
  const toolCalls = choice.message.tool_calls?.filter(
    (tc): tc is ChatCompletionMessageFunctionToolCall => tc.type === "function",
  );

  const makeChunk = (
    delta: ChatCompletionChunk.Choice.Delta,
  ): ChatCompletionChunk => ({
    id: completion.id,
    object: "chat.completion.chunk",
    created: completion.created,
    model: completion.model,
    choices: [{ index: 0, delta, finish_reason: null, logprobs: null }],
  });

  const chunks: ChatCompletionChunk[] = [];

  // Content chunks
  for (let i = 0; i < content.length; i += STREAM_CHUNK_SIZE) {
    chunks.push(
      makeChunk({
        role: "assistant",
        content: content.slice(i, i + STREAM_CHUNK_SIZE),
      }),
    );
  }

  // Tool call argument chunks
  for (const [tcIdx, tc] of (toolCalls ?? []).entries()) {
    const args = tc.function.arguments;
    for (let i = 0; i < args.length; i += STREAM_CHUNK_SIZE) {
      chunks.push(
        makeChunk({
          role: "assistant",
          tool_calls: [
            {
              index: tcIdx,
              id: tc.id,
              type: "function",
              function: {
                name: i === 0 ? tc.function.name : "",
                arguments: args.slice(i, i + STREAM_CHUNK_SIZE),
              },
            },
          ],
        }),
      );
    }
  }

  // Set finish_reason on last chunk
  if (chunks.length === 0) {
    chunks.push(makeChunk({ role: "assistant" }));
  }