Summary
I'm trying to run a multi-agent setup using google-adk==1.9.0, structured as follows. When running adk web from one level above the main_agent directory, I get the following error:

{"error": "[WIP] _load_from_yaml_config: _load_from_yaml_config is not ready for use."}

I want to confirm if this is expected behavior or a bug in the ADK library.

Project Structure
main_agent/

• init.py
• agent.py
• agent_tools.py
• sub_agents/
  -- sub_agent1/
  --- init.py
  --- agent.py
  -- sub_agent2/
  --- init.py
  --- agent.py
  -- sub_agent3/
  --- init.py
  --- agent.py

main_agent/agent.py

from .sub_agents.sub_agent1.agent import sub_agent_1
from .sub_agents.sub_agent2.agent import sub_agent_2
from .sub_agents.sub_agent3.agent import sub_agent_3
from google.adk.agents import Agent
from .agent_tools import tool_1, tool_2, tool_3

sub_agent_1.tools = [tool_1]
sub_agent_2.tools = [tool_2]
sub_agent_3.tools = [tool_3]

main_agent = Agent(
    name="main_agent",
    description="xxxxxxxx",
    instruction="You are an agent xxxxxxxxxxxx.",
    sub_agents=[sub_agent_1, sub_agent_2, sub_agent_3],
    model="gemini-2.0-flash"
)

sub_agents/sub_agent1/agent.py (example)

from google.adk.agents import Agent

sub_agent_1 = Agent(
    name="sub_agent_1",
    description="xxxxxx",
    tools=[],
    instruction="xxxxxxxx",
    model="gemini-2.0-flash"
)

Steps to Reproduce
Install google-adk==1.9.0

Run adk web from the directory one level above main_agent/

Observe the error message in the logs or browser:

json
Copy
Edit
{"error": "[WIP] _load_from_yaml_config: _load_from_yaml_config is not ready for use."}
Expected Behavior
ADK should be able to load agents defined purely in Python without relying on YAML configuration.

Environment
OS: 15.5 (24F74)

Python version: 3.12.4

google-adk version: 1.9.0

How you are running it: adk web

Additional Context
I am not using a .yaml file, just Python-based agent definitions.

Is _load_from_yaml_config being called automatically even if I define agents in Python?