The three Cs

Ron Jeffries named the three parts a story has. The Card is the written placeholder: the Connextra sentence plus enough to remember the intent. It is deliberately too short to build from alone — its job is to hold a place in the backlog and trigger a conversation, not to specify everything. The Conversation is the talk between Operator, Author, and stakeholders that fills in the detail the card omits. It is deferred on purpose: detail decided too early is detail decided with the least information, so the conversation happens when the rung is about to be built.

The Confirmation is the acceptance check — how both sides agree the story is done. It pins the conversation's conclusions to something observable, so “done” is a fact rather than an opinion. The Confirmation is the seed of the Given/When/Then acceptance criteria of A2.04. Together, the three Cs are why a card can be one sentence and still carry a whole unit of work: the sentence is the promise, the conversation is where the detail goes, the confirmation is the proof.

A contract tries to fix every detail before any work begins. A story fixes only the promise of value (the card) and the test of done (the confirmation), and leaves the rest to the conversation. This is deliberate: deferring detail to the latest responsible moment means it is decided with the most information. A frozen contract written first is the big-bang spec failure of A1.01.2 — detail decided when the least is known, then reworked when reality arrives.

Move the slider to vary how much detail is fixed up front. As more is fixed early, less information is available when each decision is made, and the rework risk rises. At the left end, all detail is deferred to the conversation — a promise. At the right end, everything is fixed first — a frozen contract. The readout reports the trade computed from the model.

Take the Portal rung “enrol in a course”. The Card is one line plus a note: “As a learner, I want to enrol in a course, so that I can study it”, enrolment once per learner per course. The Conversation settles what the card omits — what happens on a second enrol, whether there is a confirmation step — when the rung is built, not guessed up front. The Confirmation pins it: enrolled exactly once, a second enrol does not change the count. That check is already the skeleton of an A2.04 scenario.

# Card — the written placeholder (short on purpose)
"As a learner, I want to enrol in a course, so that I can study it."
# note: enrolment is once per learner per course

# Conversation — detail deferred to the moment of building
#   what happens on a second enrol? is there a confirmation step?

# Confirmation — the acceptance check (a Given/When/Then skeleton)
#   given a learner not enrolled, when they enrol,
#   then they are enrolled exactly once — a second enrol does not change the count

The three Cs are why a card can be one sentence and still carry a unit of work. The Card holds a place and triggers a conversation; the Conversation holds the detail, deferred to where the information is greatest; the Confirmation pins “done” to an observable check. A story is a promise plus a conversation, not a contract frozen up front — fixing detail early only moves the cost to rework. With the form and the Cs in hand, the closing dive writes real Portal cards.

Primary sources for the three Cs and the story as a promise, and where it connects in the course.