fix: move BeforeMultiAgentInvocationEvent to stream_async

Author: JackYPCOnline

src/strands/multiagent/graph.py

@@ -469,7 +469,6 @@ def __call__(
         if invocation_state is None:
             invocation_state = {}
 
-        self.hooks.invoke_callbacks(BeforeMultiAgentInvocationEvent(self, invocation_state))
         return run_async(lambda: self.invoke_async(task, invocation_state))
 
     async def invoke_async(
@@ -517,6 +516,8 @@ async def stream_async(
         if invocation_state is None:
             invocation_state = {}
 
+        self.hooks.invoke_callbacks(BeforeMultiAgentInvocationEvent(self, invocation_state))
+
         logger.debug("task=<%s> | starting graph execution", task)
 
         # Initialize state

src/strands/multiagent/swarm.py

@@ -288,7 +288,6 @@ def __call__(
         """
         if invocation_state is None:
             invocation_state = {}
-        self.hooks.invoke_callbacks(BeforeMultiAgentInvocationEvent(self, invocation_state))
         return run_async(lambda: self.invoke_async(task, invocation_state))
 
     async def invoke_async(
@@ -337,6 +336,8 @@ async def stream_async(
         if invocation_state is None:
             invocation_state = {}
 
+        self.hooks.invoke_callbacks(BeforeMultiAgentInvocationEvent(self, invocation_state))
+
         logger.debug("starting swarm execution")
 
         if not self._resume_from_session: