Practice and application
The practice is the interface; an application is an implementation of it. The practice states what must hold, who may act, and how work travels — and it never names a tool. Adopting one tracker over another, or replacing a pipeline, changes the application and leaves the practice untouched.
What follows from the split
The practice must be declared. A system states the standards it adopts and the way it works, rather than inheriting them by convention or by whoever last touched it.
The practice must be portable. Nothing in it may depend on a capability only one tool happens to have.
The practice
The interface — what must hold, who may act, and how work travels. Normative and technology-agnostic: it names no tool, and nothing in it may depend on a capability only one tool happens to have.
The practice is durable. It is the source from which any application is derived, and the thing that survives that application being replaced.
An application
One technology-specific instantiation of the practice — the trackers, pipelines, templates and agents through which a system actually runs it. An application declares everything the practice deliberately leaves open: its personas, its disciplines, its standards, and whatever work subtypes it needs.
An application is replaceable. Changing tracker, language or pipeline changes the application and leaves the practice untouched — which is the entire reason the two are kept apart.
Which side something falls on
The test is the one the naming discipline uses: could somebody instantiating this same practice somewhere else have made a different choice? If yes, it is an application decision.
| The practice says | An application decides |
|---|---|
| Every item carries exactly one type | That a label carries it, and what the labels are called |
| Every request enters one door | Which tracker is the door |
| Something on the item calls it to action | Whether that is an assignee, a label, a column or a notification |
| A role must be able to reach what it needs | Where that lives, and how it is fetched |
| A standard states how its conformance is determined | What form the standard is declared in |
A team with no practice does not learn a model and then comply with it. They use tooling that embodies it and learn by being unable to do the wrong thing easily. That makes the practice the specification of the machinery rather than onboarding material — and it is why the split is load-bearing rather than tidy.
What a system must declare is written on declaring an application.