startProviderResponse function

Future<StreamedResponse> startProviderResponse(AssistantMessageEventStream eventStream, ProviderStreamState state, Client httpClient, Request request, CancelToken? cancelToken, FutureOr<void> onResponse(int statusCode, Map<String, String> headers, Model)?,)

Sends request (via sendProviderRequest), runs the adapter's onResponse hook, and pushes the StartEvent with the initial snapshot.

Shared by the adapters: pi fires start right after the response headers arrive, before the body stream is consumed.

Implementation

Future<http.StreamedResponse> startProviderResponse(
  AssistantMessageEventStream eventStream,
  ProviderStreamState state,
  http.Client httpClient,
  http.Request request,
  CancelToken? cancelToken,
  FutureOr<void> Function(int statusCode, Map<String, String> headers, Model)?
  onResponse,
) async {
  // Issue #1554: the model's request-scoped watchdog windows (a roles
  // chain entry's `connectTimeoutMs`/`streamIdleTimeoutMs`) ride the send
  // — the top precedence layer, above the URL-keyed tuning table. The
  // scope label cites THE LEG THAT RAN (review round 1): an idle-only
  // override never names its scope on a connect-stall note, and vice
  // versa — a leg that ran the global default keeps the bare text.
  final response = await sendProviderRequest(
    httpClient,
    request,
    cancelToken,
    connectTimeout: state.model.connectTimeout,
    timeoutSource: state.model.connectTimeout == null
        ? null
        : state.model.timeoutScopeLabel,
  );
  await onResponse?.call(response.statusCode, response.headers, state.model);
  eventStream.push(StartEvent(partial: state.snapshot()));
  return response;
}