LiteLLM

The border post station served three mail routes at once: the northern kingdom, the southern port and the mountains. Each route's messengers required different forms, sealing wax and fee rules, and the counter clerks recorded exceptions every day.

Merchants in the city only want to send letters, not learn the rules of every mail route. But when the northern kingdom raises prices or the southern port is blocked, the merchants' ledgers and processes have to change accordingly.

The stationmaster first wrote a thick manual and had the clerks convert according to it. The manual quickly became outdated, no one knew how to fill in newly added mail routes, and when errors occurred, no one knew which courier to contact.

Later the stationmaster set up a unified counter. Merchants submitted letters in only one format, and the counter then decided which route to take, how to change the sealing wax, and which account to charge the fee to.

The counter also added rules: valuable letters take the fast route, ordinary letters take the cheap route; if a route breaks, switch to a backup; if a merchant exceeds budget, stop it first and have a supervisor confirm.

A few months later, adding a new mail route no longer required changing forms across the whole city. The accountant could see how much each party spent, and the stationmaster could trace whether a failure was at the counter, on the mail route, or in the letter itself. Merchants finally turned their attention back to the content of the letters.

The unified counter did not erase regional differences either. The northern kingdom still had its northern sealing wax, the southern port still had its southern billing, and the mountain region still feared road closures in the rainy season; these troubles were simply no longer placed on every merchant's desk.

What the stationmaster valued most was replaceability. If one mail route raised prices, the counter could divert some letters; if one route failed, the counter could explain where the failure occurred. A unified entry point turned multiple couriers from a chaotic choice into a governable network. Later, when newcomers started, the old masters no longer first talked about abstract categories. Instead, they had them review that failure: where intuition had originally been relied on, why the first fix was not enough, and how the new arrangement kept risk in a place that could be checked. Only when they could explain these details clearly and also point out when to keep using the method and when to upgrade it were they considered to truly understand the approach. Later they also had newcomers rehearse with this method: first have the newcomers do it the old way and see how errors appeared; then redo it under the new rules and see which step was blocked in advance and which step left evidence. If newcomers could only recite names, they would still misuse it in similar scenarios; only those who could state the applicable boundaries, costs, and remedies after failure were allowed to take work independently.