Sample contract · MD directive · ARC 2.0.0-beta.28

`:::step`

Nest a single step body under steps; full live sample lives with the steps container.

Web Device Markdown directive — not an AUP primitive; not a theme/site layout component.

Sample contract

Field	Value
Purpose	Single step container inside `::::steps`
Boundaries	Must nest under `::::steps`; leaf `::step` cannot hold a body
Author entry	`:::step{title=…}` nested under `::::steps`
Surface	Web Device document (child view of steps)
Public status	`released`
Fallback / failure	Outside steps → no full steps chrome; wrong fence → empty body
Verification	Pair page steps · `arc --version` = `2.0.0-beta.28`

:::step only has meaning inside ::::steps. Full fence rule and live render:

Source (must be nested):

::::steps
:::step{title="One unit, one body"}
This body is a step item. It is not a free-standing tutorial primitive.
:::
::::

Rendered:

One unit, one body
This body is a step item. It is not a free-standing tutorial primitive.

See also the fuller multi-step sample on steps.

Situation	Expected result
`:::step` without outer `::::steps`	No complete steps contract
Leaf `::step`	Cannot hold a body
Missing `title`	Step still may render; title chrome omitted

Item	Value
Baseline	`2026-08-09` · `arc --version` → `2.0.0-beta.28`
Capability row	`docs/aup/capability-matrix.md` §6 · `:::step`
Implementation	`content-reader.ts` (child name `step`) · `stepsDirectiveToAup`
Public routes	`/en/docs/web-device/markdown/step/` · `/zh/docs/web-device/markdown/step/`
Local run	`arc service start --blocklet blocklets/arcblock --port 4900` · open this page and steps
Accept	Nested step body renders inside steps chrome