Billing anomaly alerts run on a 24–48 hour lag. The retry loop is already an invoice by the time anyone sees it. The control that catches it is per-session, in-process, and lives in the orchestration layer — profiled envelope, 3x P95 trip, defined degradation.
You approved Copilot. Then Claude Code. The invoice is a surprise and nobody owns the line item. The window for token FinOps is open right now — proxy, attribution, routing, anomaly detection. Build it before the next quarterly review.
Two LangChain agents burned $47K in eleven days. The model worked. The budget math didn't. Multi-agent cost is a heavy-tailed distribution, monitoring is structurally too late, and only synchronous SDK-level enforcement stops the spiral.
Why production inference bills always exceed estimates — and the Finance-Engineering governance framework for per-agent budgets, model routing, and cost forecasting without capability degradation.