A forecast is only a forecast if the worst case is bounded. Set hard dollar ceilings at the org, team, user and key scope, decompose next month's number into them, and know exactly which code your client gets when one bites.
A step-by-step path from a funded nRouter account to a production LLM call with a spend ceiling on it — create a scoped key, point your existing OpenAI client at one base URL, cap the key, and verify the cost header came back.
A budget caps dollars over a window and answers 402; a rate limit caps RPM/TPM right now and answers 429. Here is how to classify the risk, set each control in the dashboard, and write client code that tells the three rejections apart.
Auto top-up keeps your balance from hitting zero mid-traffic, but on its own it removes the only thing that stops a runaway. Here is the three-number configuration — threshold, top-up amount, and a Block-mode budget — that makes it safe.
Every request through an LLM gateway clears four independent gates before a provider ever sees it — credit balance, budget cap, RPM/TPM rate limit, and guardrails. Each has its own status code, its own scope, and its own fix.
A budget is a dollar allowance attached to a scope and a window. Here is how to create one on each of the four scopes, which status code each returns when it fires, and how to prove the cap bites before you trust it in production.
A coding agent turns one task into hundreds of model calls. Here is how a gateway gives each run a hard ceiling that holds under burst, a fallback path that does not strand a half-finished edit, and a cost you can read per task.
nRouter vs Portkey, the closest true competitor on governance breadth. What "plan-dependent" costs you beyond the price, where Portkey is genuinely ahead, and the two error codes a budget ceiling returns.
nRouter is a managed LLM gateway. One OpenAI-compatible key reaches every model in your catalog, every response carries its exact cost, and guardrails, budgets, A/B tests and prompt management are on every plan, not gated.
An agent sends hundreds of calls without a human in the loop, so the loop bug you have not written yet is a billing event. Give each agent role its own key with its own rate ceiling and spend cap, enforced at the gateway rather than in the agent code that has the bug.
