Enhance Agent and Flow Execution Logic

- Updated the Agent class to automatically detect the event loop and return a coroutine when called within a Flow, simplifying async handling for users.
- Modified Flow class to execute listeners sequentially, preventing race conditions on shared state during listener execution.
- Improved handling of coroutine results from synchronous methods, ensuring proper execution flow and state management.

These changes enhance the overall execution logic and user experience when working with agents and flows in CrewAI.

lib/crewai/src/crewai/agent/core.py

@@ -8,6 +8,7 @@ import time
 from typing import (
     TYPE_CHECKING,
     Any,
+    Coroutine,
     Final,
     Literal,
     cast,
@@ -69,6 +70,7 @@ from crewai.security.fingerprint import Fingerprint
 from crewai.tools.agent_tools.agent_tools import AgentTools
 from crewai.utilities.agent_utils import (
     get_tool_names,
+    is_inside_event_loop,
     load_agent_from_repository,
     parse_tools,
     render_text_description_and_args,
@@ -1699,16 +1701,16 @@ class Agent(BaseAgent):
         self,
         messages: str | list[LLMMessage],
         response_format: type[Any] | None = None,
-    ) -> LiteAgentOutput:
+    ) -> LiteAgentOutput | Coroutine[Any, Any, LiteAgentOutput]:
         """
         Execute the agent with the given messages using the AgentExecutor.
 
         This method provides standalone agent execution without requiring a Crew.
         It supports tools, response formatting, and guardrails.
 
-        When called from within a sync Flow method, the Flow framework automatically
+        When called from within a Flow (sync or async method), this automatically
-        runs the method in a thread pool, so this works seamlessly. For async Flow
+        detects the event loop and returns a coroutine that the Flow framework
-        methods, use kickoff_async() instead.
+        awaits. Users don't need to handle async explicitly.
 
         Args:
             messages: Either a string query or a list of message dictionaries.
@@ -1718,10 +1720,15 @@ class Agent(BaseAgent):
 
         Returns:
             LiteAgentOutput: The result of the agent execution.
+            When inside a Flow, returns a coroutine that resolves to LiteAgentOutput.
 
         Note:
-            If called from an async context (not through Flow), use kickoff_async().
+            For explicit async usage outside of Flow, use kickoff_async() directly.
         """
+        # Magic auto-async: if inside event loop (e.g., inside a Flow),
+        # return coroutine for Flow to await
+        if is_inside_event_loop():
+            return self.kickoff_async(messages, response_format)
 
         executor, inputs, agent_info, parsed_tools = self._prepare_kickoff(
             messages, response_format

lib/crewai/src/crewai/flow/flow.py

@@ -1522,11 +1522,9 @@ class Flow(Generic[T], metaclass=FlowMeta):
                     if self.last_human_feedback is not None
                     else result
                 )
-                tasks = [
+                # Execute listeners sequentially to prevent race conditions on shared state
-                    self._execute_single_listener(listener_name, listener_result)
+                for listener_name in listeners_for_result:
-                    for listener_name in listeners_for_result
+                    await self._execute_single_listener(listener_name, listener_result)
-                ]
-                await asyncio.gather(*tasks)
         else:
             await self._execute_listeners(start_method_name, result)
 
@@ -1595,12 +1593,14 @@ class Flow(Generic[T], metaclass=FlowMeta):
             if asyncio.iscoroutinefunction(method):
                 result = await method(*args, **kwargs)
             else:
+                # Run sync methods in thread pool for isolation
+                # This allows Agent.kickoff() to work synchronously inside Flow methods
                 import contextvars
 
                 ctx = contextvars.copy_context()
                 result = await asyncio.to_thread(ctx.run, method, *args, **kwargs)
 
-            # Auto-await coroutines from sync methods (still useful for explicit coroutine returns)
+            # Auto-await coroutines returned from sync methods (enables AgentExecutor pattern)
             if asyncio.iscoroutine(result):
                 result = await result
 
@@ -1749,11 +1749,11 @@ class Flow(Generic[T], metaclass=FlowMeta):
                     listener_result = router_result_to_feedback.get(
                         str(current_trigger), result
                     )
-                    tasks = [
+                    # Execute listeners sequentially to prevent race conditions on shared state
-                        self._execute_single_listener(listener_name, listener_result)
+                    for listener_name in listeners_triggered:
-                        for listener_name in listeners_triggered
+                        await self._execute_single_listener(
-                    ]
+                            listener_name, listener_result
-                    await asyncio.gather(*tasks)
+                        )
 
                 if current_trigger in router_results:
                     # Find start methods triggered by this router result
@@ -1969,11 +1969,9 @@ class Flow(Generic[T], metaclass=FlowMeta):
                         if self.last_human_feedback is not None
                         else listener_result
                     )
-                    tasks = [
+                    # Execute listeners sequentially to prevent race conditions on shared state
-                        self._execute_single_listener(name, feedback_result)
+                    for name in listeners_for_result:
-                        for name in listeners_for_result
+                        await self._execute_single_listener(name, feedback_result)
-                    ]
-                    await asyncio.gather(*tasks)
 
         except Exception as e:
             # Don't log HumanFeedbackPending as an error - it's expected control flow

lib/crewai/tests/cassettes/agents/test_multiple_agents_in_same_flow.yaml

@@ -47,16 +47,15 @@ interactions:
     uri: https://api.openai.com/v1/chat/completions
   response:
     body:
-      string: "{\n  \"id\": \"chatcmpl-Cy7awLGYnYfpKGEeRhKlU90FltH7L\",\n  \"object\":
+      string: "{\n  \"id\": \"chatcmpl-CyRKzgODZ9yn3F9OkaXsscLk2Ln3N\",\n  \"object\":
-        \"chat.completion\",\n  \"created\": 1768444910,\n  \"model\": \"gpt-4o-mini-2024-07-18\",\n
+        \"chat.completion\",\n  \"created\": 1768520801,\n  \"model\": \"gpt-4o-mini-2024-07-18\",\n
         \ \"choices\": [\n    {\n      \"index\": 0,\n      \"message\": {\n        \"role\":
         \"assistant\",\n        \"content\": \"I now can give a great answer  \\nFinal
-        Answer: Hello and welcome! It's wonderful to see you here. I hope you're having
+        Answer: Hello! Welcome! I'm so glad to see you here. If you need any assistance
-        a fantastic day. If there's anything you need or if you have any questions,
+        or have any questions, feel free to ask. Have a wonderful day!\",\n        \"refusal\":
-        feel free to ask. I'm here to help and make your experience enjoyable!\",\n
+        null,\n        \"annotations\": []\n      },\n      \"logprobs\": null,\n
-        \       \"refusal\": null,\n        \"annotations\": []\n      },\n      \"logprobs\":
+        \     \"finish_reason\": \"stop\"\n    }\n  ],\n  \"usage\": {\n    \"prompt_tokens\":
-        null,\n      \"finish_reason\": \"stop\"\n    }\n  ],\n  \"usage\": {\n    \"prompt_tokens\":
+        127,\n    \"completion_tokens\": 43,\n    \"total_tokens\": 170,\n    \"prompt_tokens_details\":
-        127,\n    \"completion_tokens\": 57,\n    \"total_tokens\": 184,\n    \"prompt_tokens_details\":
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@@ -69,7 +68,7 @@ interactions:
       Content-Type:
       - application/json
       Date:
-      - Thu, 15 Jan 2026 02:41:51 GMT
+      - Thu, 15 Jan 2026 23:46:42 GMT
       Server:
       - cloudflare
       Set-Cookie:
@@ -87,17 +86,17 @@ interactions:
       cf-cache-status:
       - DYNAMIC
       content-length:
-      - '1074'
+      - '990'
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-      - '1019'
+      - '880'
       openai-project:
       - OPENAI-PROJECT-XXX
       openai-version:
       - '2020-10-01'
       x-envoy-upstream-service-time:
-      - '1242'
+      - '1160'
       x-openai-proxy-wasm:
       - v0.1
       x-ratelimit-limit-requests:
@@ -165,18 +164,18 @@ interactions:
     uri: https://api.openai.com/v1/chat/completions
   response:
     body:
-      string: "{\n  \"id\": \"chatcmpl-Cy7ayZre6crr19UyujJE9YbNxDndk\",\n  \"object\":
+      string: "{\n  \"id\": \"chatcmpl-CyRL1Ua2PkK5xXPp3KeF0AnGAk3JP\",\n  \"object\":
-        \"chat.completion\",\n  \"created\": 1768444912,\n  \"model\": \"gpt-4o-mini-2024-07-18\",\n
+        \"chat.completion\",\n  \"created\": 1768520803,\n  \"model\": \"gpt-4o-mini-2024-07-18\",\n
         \ \"choices\": [\n    {\n      \"index\": 0,\n      \"message\": {\n        \"role\":
         \"assistant\",\n        \"content\": \"I now can give a great answer  \\nFinal
-        Answer: As we conclude our conversation, I just want to take a moment to express
+        Answer: As we reach the end of our conversation, I want to express my gratitude
-        my heartfelt gratitude for your time and engagement. It has been a pleasure
+        for the time we've shared. It's been a pleasure assisting you, and I hope
-        interacting with you. I wish you all the best in your future endeavors. May
+        you found our interaction helpful and enjoyable. Remember, whenever you need
-        your path ahead be filled with success and happiness. Farewell, and until
+        assistance, I'm just a message away. Wishing you all the best in your future
-        we meet again!\",\n        \"refusal\": null,\n        \"annotations\": []\n
+        endeavors. Goodbye and take care!\",\n        \"refusal\": null,\n        \"annotations\":
-        \     },\n      \"logprobs\": null,\n      \"finish_reason\": \"stop\"\n    }\n
+        []\n      },\n      \"logprobs\": null,\n      \"finish_reason\": \"stop\"\n
-        \ ],\n  \"usage\": {\n    \"prompt_tokens\": 126,\n    \"completion_tokens\":
+        \   }\n  ],\n  \"usage\": {\n    \"prompt_tokens\": 126,\n    \"completion_tokens\":
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@@ -189,7 +188,7 @@ interactions:
       Content-Type:
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       Date:
-      - Thu, 15 Jan 2026 02:41:53 GMT
+      - Thu, 15 Jan 2026 23:46:44 GMT
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+      - '1363'
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-      - '1550'
+      - '1605'
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