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Agent configured with WithStream(true) that emits lifecycle events as the loop runs — text deltas, tool calls, run finished. Source: examples/agent_with_stream/

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What it demonstrates

  • Stream() returning <-chan AgentEvent
  • Handling TEXT_MESSAGE_CONTENT, tool lifecycle events, and RUN_FINISHED
  • Built-in tools with auto-approval

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Run

From examples/: 
go run ./agent_with_stream "What's the weather in Tokyo?"
go run ./agent_with_stream "What is 15 + 27?"

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Key code

Enable streaming at construction, then consume the event channel: 
a, err := agent.NewAgent(
    agent.WithLLMClient(llmClient),
    agent.WithStream(true),
    agent.WithToolRegistry(reg),
    agent.WithToolApprovalPolicy(agent.AutoToolApprovalPolicy()),
)

eventCh, err := a.Stream(ctx, prompt, nil)
if err != nil {
    log.Fatal(err)
}
for ev := range eventCh {
    if ev == nil {
        continue
    }
    switch ev.Type() {
    case agent.AgentEventTypeTextMessageContent:
        if t, ok := ev.(*agent.AgentTextMessageContentEvent); ok {
            fmt.Print(t.Delta)
        }
    case agent.AgentEventTypeRunFinished:
        // result and LLMUsage available on AgentRunFinishedEvent.Result
    case agent.AgentEventTypeRunError:
        if t, ok := ev.(*agent.AgentRunErrorEvent); ok {
            log.Println("error:", t.Message)
        }
    }
}
See Streaming for all event types and AG-UI Protocol for frontend integration.

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Expected output

Tokens print to stdout as they arrive, with no trailing newline until the run finishes: 
The current weather in Tokyo is 18°C, partly cloudy with light winds from the northeast.
With SHOW_LLM_USAGE=true a usage footer follows on a new line. Tool lifecycle events are consumed silently in this example — add a case for AgentEventTypeToolCallStart to log them.

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Learn more

Streaming

Event types and consumption patterns

Stream + Conversation

Streaming with persisted history

AG-UI

SSE server for web frontends