Governance of agent behavior cannot be expressed as natural-language prompts or markdown policies because the agent bypasses them at runtime; it must be enforced deterministically at the API gateway layer that sits between the agent and the tools/backends it calls.
This relocates the trust boundary for agent safety from the model's instruction-following to infrastructure that is immune to prompt injection and model behavior drift, making security guarantees deterministic rather than probabilistic.
Any system where an autonomous component decides which privileged backend operations to invoke should enforce authorization on the invocation path, not in the component's instructions — the same reason you don't rely on client-side validation.
the agent during execution
Security and governance must be enforced in infrastructure, not in natural language prompts.