Preflight

Before a live exercise, verify current documentation and customer policy for:

• repository and data boundary;
• supported surface and profile syntax;
• permitted tools and MCP access;
• reviewer, meter, escalation, and stop guard.

Use a non-sensitive starter task. A manual profile review is the fallback.

A role charter

.github/agents/
└── test-writer.md

A profile names one job, allowed inputs and tools, validation, stop conditions, and a manual fallback. It does not grant new authority.

Least privilege

Demo task

Add tests for `validateEmail`.
- `"ada@example.com"` returns `true`.
- `"invalid"` returns `false`.
- `""` returns `false`.
- Change tests only.
- Run the verified focused test command.

Review the diff and test result separately. Stop if production code needs to change.

Pick the smallest extension