Events & Hooks

The framework exposes a typed EventBus and lifecycle hooks for observability and integration.

EventBus

Use EventBus to publish/subscribe runtime events such as:

• turn boundaries
• tool lifecycle
• GUI updates
• subagent interaction events

Hooks

Common hooks include:

• onSessionStart
• onSessionEnd
• onToolCall
• onToolResult
• onSubagentStep
• onAgentTransfer
• onTurnLatency
• onMemoryExtraction
• onBackgroundNotification — fired when a background notification (BackgroundAgent, tool-completion bridge, interactive subagent question, or VoiceSession.notifyBackground) is delivered to the LLM. The event includes label, priority, publishedAtMs, deliveredAtMs, deferredMs, and the envelope correlationId. See Background Agents.
• onError

Hooks are ideal for logging, tracing, and metrics.