you order and
a tray appears,
but what happened
in between?

image: ai-generated (gpt-image-2)

every computable piece has this shape

a box with clear edges brings its own test

if you know the input and the expected output, you already have a test.

the sender is a box

which colour stands for which character is an agreement within the team.

what enters the receiver?

your eyes see red, but the box only sees four numbers.

same reading, two rules

the rule decides what the numbers mean, and a test decides which rule is right.

boxes connect when their edges agree

every boundary needs an agreement about the form and meaning of the data.

to find the fault, follow the data
from one boundary to the next.

the question is up to which boundary the data are still correct.

one box from the outside

open a box only as far as your question requires.

the shape survives every level

two relationships, two questions

both cut a problem, once into steps in a row and once into smaller work inside.

the right level is the one
you can test.

every box leaves two questions

an AI agent is a box, too

you do not have to trust a box when you have a test for it.

inside the box,
a program works
through the order
step by step.

image: ai-generated (gpt-image-2.5-flare)