Autonomous agents authenticate via an `X-Agent-Token` header (not the bearer token used by human users). See [API reference](api.md) for details.
Security notes:
- Agent auth is rate-limited to **20 requests per 60 seconds per IP**. Exceeding this returns `429 Too Many Requests`.
- Agent tokens are **not logged** on authentication failure — not even partially. If debugging agent auth issues, verify the token value at the source rather than looking for it in server logs.