Module events 

Available on crate feature managed-agents-preview only.

Session events: typed user / agent / session / span events.

Communication with a session is event-based. You send user.* events and receive agent.*, session.*, and span.* events back. Every event in this module is forward-compatible: an unknown wire type tag falls through to SessionEvent::Other preserving the raw JSON, so brand-new server variants don’t break the build.

Structs

AgentMessageEvent

agent.message: text content blocks the agent emitted.

AgentThinkingEvent

agent.thinking: extended-thinking content.

AgentThreadMessageReceivedEvent

agent.thread_message_received. The agent received a message from another thread (typically a sub-agent responding to the coordinator).

AgentThreadMessageSentEvent

agent.thread_message_sent. The agent sent a message to another thread (typically the coordinator delegating to a sub-agent).

AgentToolResultEvent

agent.tool_result.

AgentToolUseEvent

agent.tool_use: agent invokes a pre-built tool.

EventEnvelope

Common envelope fields present on most events. Used as the body of any event that has no additional payload beyond the envelope.

EventStreamstreaming

SSE-backed stream of SessionEvents for a Managed Agents session.

Events

Namespace handle for session-events operations.

SessionErrorEvent

session.error. Includes a typed error payload with retry status.

SessionStatusIdleEvent

session.status_idle. Carries an optional stop_reason describing why the agent paused.

SessionThreadCreatedEvent

session.thread_created. Carries the new thread’s ID and the model the spawned agent runs against.

SpanModelRequestEndEvent

span.model_request_end. Includes model_usage with token counts.

UserCustomToolResultEvent

user.custom_tool_result: caller-side response to an agent.custom_tool_use.

UserDefineOutcomeEvent

user.define_outcome: define an outcome the agent works toward.

UserMessageEvent

user.message: a text user message.

UserToolConfirmationEvent

user.tool_confirmation: allow / deny a pending tool call.

Enums

AgentEvaluatedPermission

Permission verdict the platform applied to a pending tool call. Returned on AgentToolUseEvent when the agent’s permission policy includes ask.

ConfirmationResult

allow / deny verdict for UserToolConfirmationEvent.

KnownSessionEvent

All event variants this SDK version recognizes.

KnownStopReason

Stop-reason variants this SDK version knows about.

OutcomeRubric

Rubric source for an outcome.

OutgoingUserEvent

One event included in a Events::send call.

SessionEvent

One event on a Managed Agents session.

StopReason

Reason the session went idle. Forward-compatible: unknown type tags fall through to Self::Other.

UserContentBlock

One block of content inside a UserMessageEvent or UserCustomToolResultEvent.

Type Aliases

AgentCustomToolUseEvent

agent.custom_tool_use: agent invokes one of the caller’s custom tools. The session pauses; respond with an OutgoingUserEvent::CustomToolResult.

AgentMcpToolResultEvent

agent.mcp_tool_result.

AgentMcpToolUseEvent

agent.mcp_tool_use: agent invokes an MCP server tool.