strands.experimental.hooks.multiagent.events

Multi-agent execution lifecycle events for hook system integration.

Deprecated: Use strands.hooks.multiagent instead.

__all__ = ['AfterMultiAgentInvocationEvent', 'AfterNodeCallEvent', 'BeforeMultiAgentInvocationEvent', 'BeforeNodeCallEvent', 'MultiAgentInitializedEvent'] module-attribute

AfterMultiAgentInvocationEvent dataclass

Bases: BaseHookEvent

Event triggered after orchestrator execution completes.

Attributes:

Name	Type	Description
source	MultiAgentBase	The multi-agent orchestrator instance
invocation_state	dict[str, Any] | None	Configuration that user passes in

Source code in strands/hooks/events.py

@dataclass
class AfterMultiAgentInvocationEvent(BaseHookEvent):
    """Event triggered after orchestrator execution completes.

    Attributes:
        source: The multi-agent orchestrator instance
        invocation_state: Configuration that user passes in
    """

    source: "MultiAgentBase"
    invocation_state: dict[str, Any] | None = None

    @property
    def should_reverse_callbacks(self) -> bool:
        """True to invoke callbacks in reverse order."""
        return True

should_reverse_callbacks property

True to invoke callbacks in reverse order.

AfterNodeCallEvent dataclass

Bases: BaseHookEvent

Event triggered after individual node execution completes.

Attributes:

Name	Type	Description
source	MultiAgentBase	The multi-agent orchestrator instance
node_id	str	ID of the node that just completed execution
invocation_state	dict[str, Any] | None	Configuration that user passes in

Source code in strands/hooks/events.py

@dataclass
class AfterNodeCallEvent(BaseHookEvent):
    """Event triggered after individual node execution completes.

    Attributes:
        source: The multi-agent orchestrator instance
        node_id: ID of the node that just completed execution
        invocation_state: Configuration that user passes in
    """

    source: "MultiAgentBase"
    node_id: str
    invocation_state: dict[str, Any] | None = None

    @property
    def should_reverse_callbacks(self) -> bool:
        """True to invoke callbacks in reverse order."""
        return True

should_reverse_callbacks property

True to invoke callbacks in reverse order.

BeforeMultiAgentInvocationEvent dataclass

Bases: BaseHookEvent

Event triggered before orchestrator execution starts.

Attributes:

Name	Type	Description
source	MultiAgentBase	The multi-agent orchestrator instance
invocation_state	dict[str, Any] | None	Configuration that user passes in

Source code in strands/hooks/events.py

@dataclass
class BeforeMultiAgentInvocationEvent(BaseHookEvent):
    """Event triggered before orchestrator execution starts.

    Attributes:
        source: The multi-agent orchestrator instance
        invocation_state: Configuration that user passes in
    """

    source: "MultiAgentBase"
    invocation_state: dict[str, Any] | None = None

BeforeNodeCallEvent dataclass

Bases: BaseHookEvent, _Interruptible

Event triggered before individual node execution starts.

Attributes:

Name	Type	Description
source	MultiAgentBase	The multi-agent orchestrator instance
node_id	str	ID of the node about to execute
invocation_state	dict[str, Any] | None	Configuration that user passes in
cancel_node	bool | str	A user defined message that when set, will cancel the node execution with status FAILED. The message will be emitted under a MultiAgentNodeCancel event. If set to True, Strands will cancel the node using a default cancel message.

Source code in strands/hooks/events.py

@dataclass
class BeforeNodeCallEvent(BaseHookEvent, _Interruptible):
    """Event triggered before individual node execution starts.

    Attributes:
        source: The multi-agent orchestrator instance
        node_id: ID of the node about to execute
        invocation_state: Configuration that user passes in
        cancel_node: A user defined message that when set, will cancel the node execution with status FAILED.
            The message will be emitted under a MultiAgentNodeCancel event. If set to `True`, Strands will cancel the
            node using a default cancel message.
    """

    source: "MultiAgentBase"
    node_id: str
    invocation_state: dict[str, Any] | None = None
    cancel_node: bool | str = False

    def _can_write(self, name: str) -> bool:
        return name in ["cancel_node"]

    @override
    def _interrupt_id(self, name: str) -> str:
        """Unique id for the interrupt.

        Args:
            name: User defined name for the interrupt.

        Returns:
            Interrupt id.
        """
        node_id = uuid.uuid5(uuid.NAMESPACE_OID, self.node_id)
        call_id = uuid.uuid5(uuid.NAMESPACE_OID, name)
        return f"v1:before_node_call:{node_id}:{call_id}"

MultiAgentInitializedEvent dataclass

Bases: BaseHookEvent

Event triggered when multi-agent orchestrator initialized.

Attributes:

Name	Type	Description
source	MultiAgentBase	The multi-agent orchestrator instance
invocation_state	dict[str, Any] | None	Configuration that user passes in

Source code in strands/hooks/events.py

@dataclass
class MultiAgentInitializedEvent(BaseHookEvent):
    """Event triggered when multi-agent orchestrator initialized.

    Attributes:
        source: The multi-agent orchestrator instance
        invocation_state: Configuration that user passes in
    """

    source: "MultiAgentBase"
    invocation_state: dict[str, Any] | None = None