events is mixing while running single_turn agent as parallel

[maxx1958]

🔴 Required Information

Please ensure all items in this section are completed to allow for efficient
triaging. Requests without complete information may be rejected / deprioritized.
If an item is not applicable to you - please mark it as N/A

Describe the Bug:
When "single_turn" agents are executed in parallel, the context gets mixed.
Single_turn_Agent1("order 1")
Single_turn_Agent1("order 2")
Single_turn_Agent1 got
context = [
"order 1",
"order 2",
]

Single_turn_Agent2 also got
context = [
"order 1",
"order 2",
]

Steps to Reproduce:
Please provide a numbered list of steps to reproduce the behavior:

1. Install '...'
2. Run '....'
3. Open '....'
4. Provide error or stacktrace
   root_agent(
   sub_agents = [ Single_turn_Agent1 , Single_turn_Agent2 ]
   )

Asking questions that are called simultaneously

Expected Behavior:
A clear and concise description of what you expected to happen.

Single_turn_Agent1("order 1")
Single_turn_Agent1("order 2")
Single_turn_Agent1 got
context = [
"order 1",
]

Single_turn_Agent2 also got
context = [
"order 2",
]

Observed Behavior:
What actually happened? Include error messages or crash stack traces here.

Environment Details:

• ADK Library Version (pip show google-adk):
  Version: 2.1.0

• Desktop OS:** [e.g., macOS, Linux, Windows] : linux

• Python Version (python -V):
  Python 3.12.3

Model Information:

• Are you using LiteLLM: Yes
• Which model is being used: (e.g., gemini-2.5-pro)
  bedrock/us.anthropic.claude-sonnet-4-5-20250929-v1:0

---

🟡 Optional Information

Providing this information greatly speeds up the resolution process.

Regression:
Did this work in a previous version of ADK? If so, which one?

Logs:
Please attach relevant logs. Wrap them in code blocks (```) or attach a
text file.

// Paste logs here

Screenshots / Video:
If applicable, add screenshots or screen recordings to help explain
your problem.

Additional Context:
Add any other context about the problem here.

@OverRide
async def run_async(
self,
*,
args: dict[str, Any],
tool_context: ToolContext,
) -> Any:
input_schema = _get_input_schema(self.agent)
if input_schema:
try:
node_input = input_schema.model_validate(args)
except Exception as e:
return f'Error validating input: {e}'
else:
node_input = args.get('request')
print(f"# name:{self.agent.name}, node_input:{node_input}")
print(f"# name:{self.agent.name}, tool_context:{tool_context.session.events}")
try:
return await tool_context.run_node(
self.agent, node_input=node_input, use_sub_branch=True
)
except Exception as e:
return f'Error running sub-agent: {e}'

Minimal Reproduction Code:
Please provide a code snippet or a link to a Gist/repo that isolates the issue.

// Code snippet here

How often has this issue occurred?:

• Always (100%)

[maxx1958]

_SingleTurnAgentTool name:battery, node_input:get device list with battery issue

content=Content(
parts=[
Part(
text="I'll help you retrieve information about devices with security issues and battery issues."
),
Part(
function_call=FunctionCall(
args={
'request': 'get device list with security issues'
},
id='tooluse_z4B4h5OaNfK6vg7YayK12x',
name='security'
)
),
Part(
function_call=FunctionCall(
args={
'request': 'get device list with battery issues'
},
id='tooluse_IJXmFZ01iOnO3BLydn8wWA',
name='battery'
)
),
],
role='model'
...
Event(model_version=None, content=Content(
parts=[
Part(
text='get device list with security issues'
),
],
role='user'
)
...
Event(model_version=None, content=Content(
parts=[
Part(
text='get device list with battery issues'
),
],

_SingleTurnAgentTool name:security, node_input:get device list with security vulnerabilities and security issues

content=Content(
parts=[
Part(
text="I'll help you retrieve information about devices with security issues and battery issues."
),
Part(
function_call=FunctionCall(
args={
'request': 'get device list with security issues'
},
id='tooluse_z4B4h5OaNfK6vg7YayK12x',
name='security'
)
),
Part(
function_call=FunctionCall(
args={
'request': 'get device list with battery issues'
},
id='tooluse_IJXmFZ01iOnO3BLydn8wWA',
name='battery'
)
),
],
role='model'
...
Event(model_version=None, content=Content(
parts=[
Part(
text='get device list with security issues'
),
],
role='user'
)
...
Event(model_version=None, content=Content(
parts=[
Part(
text='get device list with battery issues'
),
],

[llalitkumarrr]

Hello @maxx1958 ,

Could you please try parallel worker sample and check if you observe similar behavior here as well? Kindly try this and share your observations with us.

Also we observed that you are using Litellm with Gemini models, we highly recommend using Gemini model class with gemini models.