subscriber.mdx

title	AgentSubscriber
description	Event subscriber interface for reactive agent interaction (Java)

AgentSubscriber

Implement AgentSubscriber to handle lifecycle, message, tool call, and state events during agent execution.

Event Handlers

• Request lifecycle: onRunInitialized, onRunFailed, onRunFinalized
• Lifecycle events: onRunStartedEvent, onRunFinishedEvent, onRunErrorEvent, onStepStartedEvent, onStepFinishedEvent
• Text messages: onTextMessageStartEvent, onTextMessageContentEvent, onTextMessageEndEvent
• Tool calls: onToolCallStartEvent, onToolCallArgsEvent, onToolCallEndEvent, onToolCallResultEvent
• State: onStateSnapshotEvent, onStateDeltaEvent, onMessagesSnapshotEvent, onMessagesChanged, onStateChanged
• Special: onRawEvent, onCustomEvent, and catch-all onEvent

Usage Example

agent.subscribe(new AgentSubscriber() {
  @Override
  public void onRunStartedEvent(RunStartedEvent event) {
    System.out.println("Run started: " + event.getRunId());
  }

  @Override
  public void onTextMessageContentEvent(TextMessageContentEvent event) {
    System.out.print(event.getDelta());
  }
});