Child events

Enable child streaming when internal operators or application logic need to inspect nested agent progress.

1. Forward child events

const policyReview = policyAgent.asTool({
  name: 'policy_review',
  description: 'Review a draft answer for policy risk.',
  maxTurns: 2,
  suspension: 'reject',
  stream: true,
})

Child events are forwarded only when the parent is itself consumed with stream() and the child model supports streaming.

2. Consume the parent stream

const session = { sessionId: threadId, userId: user.id };
for await (const event of supportAgent.stream({
    prompt: message,
    session: session
})) {
    if (event.type === 'agent_tool_event') {
        await operationsLog.write({
            parentTurn: event.turn,
            childAgentId: event.agentId,
            childAgentName: event.agentName,
            toolName: event.toolName,
            internalCallId: event.internalCallId,
            childEventType: event.event.type,
        });
    }
    if (event.type === 'response') {
        await responses.save(event.output);
    }
}

agent_tool_event identifies the parent turn, tool and call, child agent, and wrapped child event.

3. Keep one stream owner

Consume the parent stream completely so child work, parent tool results, final output, memory writes, lifecycle callbacks, and observers can settle normally.

Do not create a second consumer for the child. Anvia forwards its enabled events through the active parent tool call.

4. Project events for clients

Nested events can contain private prompts, reasoning, tool arguments, tool results, model requests, and errors. Map them to a reviewed product status:

function toClientEvent(event: AgentStreamEvent) {
  if (event.type === 'agent_tool_event') {
    return {
      type: 'status',
      label: `Running ${event.toolName}`,
    }
  }
}

Use turn, toolName, toolCallId, internalCallId, and agentId to attach nested work to the correct delegation. Apply redaction and retention rules to operational event storage.

Next, define memory boundaries.