Drawing the line

Nadia did not begin with a model. She began with a notebook and a pen. In the course of an hour with Tom, the representative who had worked the desk longest, she wrote down the process as it actually operated: the steps in order, the person responsible for each, the rules that existed but had never been recorded, the points at which someone genuinely made a decision, the waits, and the systems consulted. The minimum order was ten units; seven countries were served; the discount was five per cent at fifty units, ten at two hundred and fifteen at five hundred, and anything above fifteen required a representative's agreement. None of this had ever been written down, and two of the three rules, it emerged, had been applied differently by the two representatives.

Two piles

The page was then sorted into two piles. Into the first went the steps that have a correct answer: whether the enquiry is complete, whether the quantity exceeds the minimum, whether the country is one the company serves, whether the buyer is an existing customer, and what the price should be. Each of these can be expressed as a rule and applied identically every time, by something that does not tire, improvise or hold an opinion. Into the second went the steps that require reasoning: whether the company is a good fit for what Kettle Co. sells, what the representative ought to know before quoting, and how the note to the buyer should be worded. There were two such steps in a dozen. That proportion is typical, and it is the single most useful fact to establish before an agent is allowed anywhere near a process for which one is accountable.

The sorted page, made executable

A workflow, in Chatterfly's vocabulary, is that sorted page made executable. Each of its steps is of one of two kinds. A deterministic step applies a rule, looks something up, displays a message or puts a question to a person, and behaves identically on every occasion. An agentic step gives a language model its instructions, the tools it may use and a budget, and allows it to reason within those limits. Both kinds run within the same process and read and write the same record. When a coding agent turned Nadia's page into a workflow, the result contained eleven steps that never involve a model and two that do: one that researches the company and forms a view, and one that composes three sentences to the buyer from figures a rule has already produced. The price is set by a rule, and the model has no part in it.

The rule decides, the model explains

The principle that makes the arrangement work can be stated briefly: the rule decides, and the model explains. Where a decision has a correct answer, a rule makes it and a model puts it into words. Where the input is untidy, a model reads it and a rule checks the result before anything acts upon it. The two kinds of step are meant to be combined, and the combination is the point of the design. Nobody at Kettle Co. wrote any of this by hand. The coding agent produced the workflow from the page, validated it and ran it, and Nadia examined the result as a diagram in which the two model steps are shown in orange.