# kb/concepts/ - Collection Contract

Ideas rather than things: architectures, patterns, protocols, workflows, recurring problems,
and the decisions taken about them. A concept explains *how* or *why*, where an entity page
records *what*.

**Quality goal:** explanatory sufficiency - the page should answer *why it is done this way*
without the reader having to open the entity pages that use it. If the explanation only makes
sense once you already know the system, it is on the wrong page.

Inherits [kb/CONTRACT.md](../CONTRACT.md) - naming, tone, linking, provenance and confidence
are defined there and are not restated here.

## Types offered

`concept` (`tools/wikitool types describe concept`).

## Decisions and ADRs

An architectural decision is a concept page prefixed `adr-NNN-`, e.g.
`adr-001-use-go-modules.md`. It records:

- **Context** - what forced a decision.
- **Decision** - what was chosen.
- **Consequences** - what this costs, not only what it buys.
- **Status** - proposed / accepted / deprecated / superseded.
- Links to every entity the decision affects.

A superseded ADR is never deleted or rewritten; a new one supersedes it and both link to the
other with `replaces` / `replaced by`.

## Outbound linking

A concept links to every entity that implements or uses it. A concept with no inbound entity
link is usually either premature or misfiled - `wikitool lint` reports it as an orphan.

Where two concepts compete, do not argue the comparison inside either page; create a page in
`kb/comparisons/` and link both to it.

## What does not belong here

- A concrete, pointable thing - that is an entity.
- A head-to-head evaluation of alternatives - that is a comparison.
- Generic textbook explanation with no connection to anything in this wiki. If no entity here
  uses it, the page is not earning its keep.