A sixty-line route table pins the two vendors an overnight LLM batch is allowed to reach

Before the gateway opens a socket it resolves the route by id, refuses any id that is not in the table, and refuses to start a batch that the remaining balance cannot finish ^[16]. The author says the third check is the one people skip, and that it buys a clean stop instead of a half-processed queue ^[16]. The alert it replaced fired at 03:14, exactly as designed. The retry loop was not reading the channel ^[3][4].

The table is what makes the permitted spend countable. Its two entries carry monthlyCapUsd fields of 400 and 150 ^[15], so the reviewed ceiling for the whole gateway is 550 dollars a month ^[20]. A subtraction policy leaves that ceiling unwritten. It defines the allowed set as everything nobody has thought of yet, and each provider the router gains adds a credential, a billing identity and a spend path that no one reviewed ^[9]. Secrets appear in the table only as a name such as LLM_KEY_VENDOR_A and are resolved at call time. The post says that is the OWASP baseline, and also what makes the route table safe to log ^[13][14].

On the night in question the router failed over, the exclude rule said "not vendor X", and the job retried. Resolution landed on a provider whose key had been added months earlier for a one-off evaluation and never removed ^[5]. "Nothing was broken. The policy allowed it, because the policy was written as a subtraction," the author wrote ^[6]. The money was bounded, since that is what prepaying buys ^[19]. The expensive part arrived two weeks later, when the returns team asked which vendor's servers had seen the free-text return reasons from that batch ^[7]. The post does not put a dollar figure on the night or an hour count on the follow-up work ^[21].

An allowlist does not close this by itself. A stale entry in the table would take a failover the same way the stale key did, and the argument for the allowlist is an argument about people: "An exclude rule that nobody can explain stays forever, because deleting it looks risky and nobody can prove what it was protecting against," the author wrote ^[11]. The claimed asymmetry is that an allowlist entry nobody can explain gets deleted in review ^[22]. The evidence offered for it is one incident at one storefront ^[1].

The vendor is the right thing to pin because it is the boundary that maps onto a contract, a data processing agreement and a bill, which the model id does not ^[18].

For the balance check to transfer, the account has to be prepaid, so that there is a remaining balance to read at dispatch time ^[1]. The credentials have to sit in one routing service, so that the checked-in table is the effective allowed set ^[2]. If the account is invoiced monthly instead, the dispatcher has no balance to compare against at 03:00, and the per-route monthlyCapUsd field is the only ceiling left ^[15].