feat(multiagent): introduce Swarm multi-agent orchestrator

Author: awsarron

src/strands/agent/agent.py

@@ -316,6 +316,9 @@ def __init__(
                 self.hooks.add_hook(hook)
         self.hooks.invoke_callbacks(AgentInitializedEvent(agent=self))
 
+        # When True, force stops the agent's event loop
+        self.stop_event_loop = False
+
     @property
     def tool(self) -> ToolCaller:
         """Call tool as a function.

src/strands/event_loop/event_loop.py

@@ -462,7 +462,7 @@ def tool_handler(tool_use: ToolUse) -> ToolGenerator:
         tracer = get_tracer()
         tracer.end_event_loop_cycle_span(span=cycle_span, message=message, tool_result_message=tool_result_message)
 
-    if kwargs["request_state"].get("stop_event_loop", False):
+    if agent.stop_event_loop or kwargs["request_state"].get("stop_event_loop", False):
         agent.event_loop_metrics.end_cycle(cycle_start_time, cycle_trace)
         yield {"stop": (stop_reason, message, agent.event_loop_metrics, kwargs["request_state"])}
         return

src/strands/multiagent/__init__.py

@@ -11,11 +11,15 @@
 from . import a2a
 from .base import MultiAgentBase, MultiAgentResult
 from .graph import GraphBuilder, GraphResult
+from .swarm import Swarm, SwarmConfig, SwarmResult
 
 __all__ = [
     "a2a",
     "GraphBuilder",
     "GraphResult",
     "MultiAgentBase",
     "MultiAgentResult",
+    "Swarm",
+    "SwarmConfig",
+    "SwarmResult",
 ]