Visibility scoping (@only / @except)

Gate individual blocks inside a body per site, template, or backend — finer-grained than the unit-level audience field.

Where audience selects whole units, wdoc's @only / @except decorators gate a single block *inside* a body. Any block can carry them, with three optional axes — sites, templates (:book, :webpage, :presentation, :ai_skill), and backends (:html, :markdown, :pdf). Values within an axis OR together; axes AND together.

wcl

body {
  p "Rendered everywhere."
  @only(templates=[:ai_skill]) callout "Agent note" { body = "Extra instruction only the skill sees." }
  @except(backends=[:pdf]) video { src = "../../assets/demo.mp4" }
}

Use it sparingly: a body that needs heavy per-view gating is usually two units in disguise (one :book, one :ai). The common legitimate cases are an agent-only callout inside shared reference material, and media that one backend can't carry.