Event Streaming

StreamPromptAsync() starts a prompt and yields events as they arrive.

Basic Pattern

await foreach (var item in sdk.StreamPromptAsync("Explain closures in one sentence."))
{
    if (item is MessageUpdateEvent message)
    {
        Console.Write(message.Delta);
    }
}

Event Types

• MessageUpdateEvent: token or text delta.
• MessageEndEvent: final message content.
• ToolStartEvent: a tool started.
• ToolUpdateEvent: streaming tool output.
• ToolEndEvent: a tool completed.
• PermissionRequestEvent: host approval is required.
• ErrorEvent: agent or transport error.

Handling Permissions While Streaming

await foreach (var item in sdk.StreamPromptAsync("Run the relevant tests."))
{
    if (item is PermissionRequestEvent permission && permission.RequestId is not null)
    {
        await sdk.PermissionResponseAsync(permission.RequestId, "allow_once");
    }
}

Production hosts should route permission requests to a human, policy engine, or trusted automation boundary.

Collecting Final Text

Use Agent and Run when you want streaming and a final result:

var run = agent.Send("Summarize this repository.");
await foreach (var item in run.StreamAsync())
{
    Console.WriteLine(item.Type);
}
var result = await run.WaitAsync();
Console.WriteLine(result.Text);