Folder-owned SubAgents - Fused

A folder SubAgent is a separate composition boundary.

subagents/researcher/
├── agent.py
├── instructions.md
├── tools/
├── mcp/
├── skills/
├── sandbox/
└── subagents/       ADK-only recursive discovery

Ownership properties

Resource	Child can own it?	Inherited from parent?
`instructions.md`	Yes	No
`tools/`	Yes	No
`mcp/`	Yes	No
`skills/`	Yes	No
`sandbox/`	Yes, additional local names	Ancestor names are available; permissions are not inherited
Agent `plugins/` or Harnest `extensions/`	No	No
`lifecycle/`	No	Root-owned
`models/` and `lib/`	No	Root namespace

The child’s private capabilities are not exposed to the parent merely because the directory is nested. Each SubAgent must declare its own Agent(sandboxes=[...]) assignments. Its tools can then call context.sandboxes["<name>"].execute(code) or aexecute(code). Child-local names cannot duplicate ancestor names.

Discovery rules

Rule	Result
`agent.py` export matches the folder name	Stable SubAgent identity
Supported child folders are discovered by location	Sandbox names additionally require explicit per-agent assignment
Unsupported root-only folder is populated	Compilation fails
Parent references the child	Harnest wires the composition

Framework behavior

Check recursive discovery and portable graph behavior before choosing the layout.