Cards and wires

An agent on the canvas is made of cards and wires, and nothing else.

A card does one thing

Each card does one thing and says so in one line. A card has doors: what it takes in, and what it gives out. The names on the doors are plain — text, email, booking, times — and one name always means one thing, on every card.

A wire carries one thing

A wire runs from a door that gives to a door that takes, and it carries exactly what the door it leaves says it carries. Every door says what KIND of thing goes through it — words, a number, a moment in time, an amount of money, a booking, a list of times, a file, or somebody — and the canvas lets you join any giving door to any taking door, because everything travels as words underneath and a name arriving where words were expected reads perfectly well. What the canvas does now is TELL YOU when the two ends do not match: it names the wire in one plain sentence, says what each end carries, and says that it will still run. That is a thing to read, not a thing that stops you. A door waiting for words takes anything, and is never named. What the canvas checks harder — a wire to a door a card does not have, a door with nothing wired into it, or a circle that feeds itself — is named the same way, and the agent cannot go to work until those are answered.

The first card needs nothing

An agent starts from a card that needs nothing before it — a box a customer types in, a message arriving, a call coming in, a clock. Every other card takes something from the card before it.

The last card gives nothing

The card that shows the customer the result is the end of the line. It takes the answer and gives nothing on, and it says so.

Wires are drawn once

The same wire is never drawn twice between the same two doors. If it were, the same words would arrive twice, so the canvas refuses it.