Function runStreamLoop

apps/sim/lib/copilot/request/go/stream.ts:122–570

(
  fetchUrl: string,
  fetchOptions: RequestInit,
  context: StreamingContext,
  execContext: ExecutionContext,
  options: StreamLoopOptions
)

 * Feature-specific normalization runs through dedicated adapters before the raw event is forwarded.
 */
export async function runStreamLoop(
  fetchUrl: string,
  fetchOptions: RequestInit,
  context: StreamingContext,
  execContext: ExecutionContext,
  options: StreamLoopOptions
): Promise<void> {
  const { timeout = ORCHESTRATION_TIMEOUT_MS, abortSignal } = options
  const filePreviewAdapterState = createFilePreviewAdapterState()

  const pathname = new URL(fetchUrl).pathname
  const requestBodyBytes = estimateBodyBytes(fetchOptions.body)
  const fetchSpan = context.trace.startSpan(`HTTP Request → ${pathname}`, 'sim.http.fetch', {
    url: fetchUrl,
    method: fetchOptions.method ?? 'GET',
    requestBodyBytes,
  })
  const fetchStart = performance.now()
  let response: Response
  try {
    response = await fetchGo(fetchUrl, {
      ...fetchOptions,
      signal: abortSignal,
      otelContext: options.otelContext,
      spanName: `sim → go ${pathname}`,
      operation: 'stream',
      attributes: {
        [TraceAttr.CopilotStream]: true,
        ...(requestBodyBytes ? { [TraceAttr.HttpRequestContentLength]: requestBodyBytes } : {}),
      },
    })
  } catch (error) {
    fetchSpan.attributes = {
      ...(fetchSpan.attributes ?? {}),
      headersMs: Math.round(performance.now() - fetchStart),
    }
    context.trace.endSpan(fetchSpan, abortSignal?.aborted ? 'cancelled' : 'error')
    throw error
  }
  const headersElapsedMs = Math.round(performance.now() - fetchStart)
  fetchSpan.attributes = {
    ...(fetchSpan.attributes ?? {}),
    status: response.status,
    headersMs: headersElapsedMs,
  }

  if (!response.ok) {
    context.trace.endSpan(fetchSpan, 'error')
    const errorText = await response.text().catch(() => '')

    if (response.status === 402) {
      throw new BillingLimitError(execContext.userId)
    }

    throw new CopilotBackendError(
      `Copilot backend error (${response.status}): ${errorText || response.statusText}`,
      { status: response.status, body: errorText || response.statusText }
    )