Flat SubAgents

Use a flat file for a small SubAgent that needs only its definition.

subagents/
└── researcher.py

subagents/researcher.py exports an AgentDefinition named researcher.

Flat SubAgent properties

Property	Rule
File	`subagents/<name>.py`
Export	Must match the filename
Instructions	Defined by the agent declaration
Private tools	Not supported
Private MCP	Not supported
Private Agent Skills	Not supported
Use from parent	Reference by name or as a graph node

Move the SubAgent into a folder when it needs private instructions or capabilities.

Create a separate capability boundary for the child agent.