Antora essential extensions

This page lists Antora extensions DevCentr / OpenShellOrg / antora-supplemental treat as essential: behavior so basic that every docs site we ship should enable it, and that we argue belongs closer to Antora core (or at least in every playbook by default).

Playbook URL style (not an extension): set urls.html_extension_style: indexify so published pages use folder paths (…/email/ for email/index.adoc). Canonical links and the sitemap follow that URL. Section landings stay index.adoc with a linked parent in nav (link text = H1); do not use .Section + Overview, do not invent overview.adoc, and do not advertise index.html in prose.

Essential Extensions / Extensions that should be in core

Site search (@antora/lunr-extension)

Package: @antora/lunr-extension (official Antora extension)

Problem: Without Lunr, the site has no client-side full-text search. Users (and Valentus Search/Ask chrome) expect a working omnibox.

Behavior: Indexes published pages at build time and ships a browser search UI. Valentus and related themes assume Lunr (or a wrapper such as @antora-supplemental/antora-search-chat) is present.

Playbook:

antora:
  extensions:
    - require: '@antora/lunr-extension'

Install the package in the playbook repo (pnpm add -D @antora/lunr-extension). Register Lunr before any wrapper that depends on it (for example antora-search-chat).

Upstream: Lunr is already the official search extension. Treat it as mandatory site plumbing for every Antora site we publish—not optional polish.

Site-wide component nav tree (@antora-supplemental/site-nav-tree)

Package: @antora-supplemental/site-nav-tree

Problem: The Default UI (and Valentus tree-only chrome) shows only the current component’s nav. Other components hide behind a drawer or breadcrumbs. Multi-component hubs make whole sections easy to miss (Org infra vs encyclopedia Infrastructure).

Behavior: After Antora builds per-component navigation, wrap NavigationCatalog#getNavigation so each page receives a site-wide forest of curated roots (existing nav trees as children). Stock nav-tree + expand/collapse JS stay — not a full navigator replacement. Prefer an include allowlist: registering a content source publishes pages/xrefs but does not add a sidebar root. Align the breadcrumb component picker with the same curation (site.keys.site_nav_tree_*).

Playbook:

antora:
  extensions:
    - require: '@antora-supplemental/site-nav-tree'
      include: [home, general-knowledge, business-bootstrap, agent-rules]
      order: [home, general-knowledge, business-bootstrap, agent-rules]

Valentus: copy the package’s ui/partials/nav-menu.hbs into hub supplemental-ui/partials/ to drop the redundant current-component title line.

Copy @antora-supplemental/nav-typology companion UI into hub supplemental-ui/ (partials/nav-tree.hbs, helpers/nav-typology.js, helpers/strip-nav-typology-emoji.js, css/nav-typology.css, img/nav-typology.svg) after enabling the extension in the playbook.

Multi-nav files vs include:: (component modules)

Antora allows multiple nav: entries in antora.yml. Each file becomes a separate nav tree concatenated as siblings under the component—not nested under your linked parents.

Anti-pattern: list modules/ROOT/nav.adoc, modules/specifications/nav.adoc, modules/secrets-manager/nav.adoc, … in antora.yml. The sidebar then shows Secrets Manager .Overview & design as if it were DevCentr IA, and clicking a deep spec page can collapse the product overview branch (especially with site-nav-tree).

Preferred: one nav: entry on ROOT; nest modules with include::module$nav.adoc[] under the linked parent (* Secrets Manager). The included file uses / * depth under that parent.

Nav typology: single tree with includes vs parallel multi-nav trees

Hub companion JS (supplemental-ui/js/site-nav-tree-current.js) keeps all depth-1 branches under an active component root expanded as a guard until legacy components finish migrating. In-doc link crossfade + scroll preservation: supplemental-ui/js/site-doc-nav.js.

Upstream note for @antora-supplemental/site-nav-tree: multi-nav concatenation behavior is documented in the extension README (hub diagram: nav-typology.svg above).

Nav typology icons (@antora-supplemental/nav-typology)

Package: @antora-supplemental/nav-typology

Problem: Structural nav labels (Diátaxis buckets, spec groupings) encoded as Unicode emoji render differently on every OS font and cannot share a site color palette.

Behavior: Enriches navigation at build time and renders a shared SVG sprite in the sidebar via companion nav-tree partial + Handlebars helpers. Strips leading structural emoji from nav titles when an icon replaces them. Tags changelog / activity-log entries and hoists them near the top of each nav branch (second slot after the landing link).

Hub overlay: site-nav-tree component roots use accent expand chevrons (not the generic component-root typology sprite). Optional per-component app logos: supplemental-ui/helpers/nav-component-logo.js + supplemental-ui/img/nav-logos/ (Antora component name → SVG/PNG). Typology icons apply to Diátaxis, spec, and changelog rows deeper in the tree.

Companion UI: copy ui/partials/nav-tree.hbs, ui/helpers/*.js, ui/css/nav-typology.css, and ui/img/nav-typology.svg from the package into hub supplemental-ui/; add hub nav-component-logo.js; link nav-typology.css in head-meta.hbs (same pattern as site-math.css).

Optional Diátaxis plugin: @antora-supplemental/nav-typology-diataxis — path/title auto-detection for tutorial / how-to / reference / explanation. Omit on non-Diátaxis sites.

Playbook: register after site-nav-tree.

antora:
  extensions:
    - require: '@antora-supplemental/site-nav-tree'
      include: [home, general-knowledge]
    - require: '@antora-supplemental/nav-typology'
    - require: '@antora-supplemental/nav-typology-diataxis'

Upstream: Prefer this over hand-pasting 🎓/🛠️/📚/🧠 in every nav.adoc. Expressive emoji stays available for CTAs and prose.

Alias versioned component root → latest start page

Package: @antora-supplemental/alias-component-to-latest

Problem: A component with only numbered versions (0.2.0, 1.0, …) publishes under /component/0.2.0/. The bare URL /component/ 404s. Shared links and naive “open the component” navigation break.

Behavior: For each component that has no empty/version: ~ version, register a versionless alias of ROOT index.adoc (latest start page) so /component/ routes to the latest start page. Same algorithm as the official Antora extension use case.

Playbook:

antora:
  extensions:
    - require: '@antora-supplemental/alias-component-to-latest'

Upstream: This should be an opt-in core playbook key (for example urls.alias_component_to_latest: true), not a forever copy-paste extension. Antora already documents the snippet; core should own the switch.

Proposal / discussion: antora/antora#291 (closed after #314; remaining gap is bare /component/ → latest, not symbolic latest/current). Comment on that thread rather than opening a duplicate unless maintainers ask for a new issue.

Official use-case docs: Redirect from component to latest version

Build-time diagrams (Mermaid + PlantUML → SVG)

Package: asciidoctor-kroki (Kroki)

Problem: Runtime-only Mermaid leaves published pages dependent on CDN JS and skips PlantUML. Authors need two stable text-diagram formats that ship as SVG.

Behavior: At Antora build time, Mermaid and PlantUML blocks are converted to SVG via Kroki (kroki-fetch-diagram: true embeds them so readers do not call Kroki at view time).

Playbook: See Antora diagram formats. Compose with Lunr/math/Valentus via antora-facto — not by loading extras into Valentus core.

Math formulas (KaTeX + AsciiDoc stem)

Problem: Docs borrow equations from design notes and leave them as raw $Hash(…)$ or plain text. Sites without a math renderer cannot grow into technical explanation pages without a retrofit.

Behavior: Every Antora site enables stem: latexmath in the playbook and loads KaTeX auto-render (site-math.js / site-math.css in Valentus, mirrored into org supplemental-ui until the next Valentus UI bundle release). Authors write \(a^2+b^2=c^2\) or [stem] blocks. Markdown/Astro sites use remark-math + rehype-katex (or equivalent) with KaTeX CSS.

Playbook:

asciidoc:
  attributes:
    stem: latexmath

Load KaTeX even when the current corpus has zero formulas — plumbing, not polish.

Build stack footer (@antora-supplemental/build-stack)

Package: @antora-supplemental/build-stack

Problem: Site footers credit the UI theme only. The real stack — Lunr, site-nav-tree, nav-typology, Kroki, page-context — lives in playbook YAML but Antora never exposes antora.extensions or asciidoc.extensions to Handlebars.

Behavior: On playbookBuilt, publishes linked HTML to site.keys.build_stack_antora_html / build_stack_asciidoc_html and infers ui_bundle_name / ui_bundle_url from ui.bundle.url. Copy companion ui/partials/footer-build-stack.hbs into hub supplemental-ui and {{> footer-build-stack}} from footer-content.hbs.

Playbook:

antora:
  extensions:
    - '@antora-supplemental/build-stack'

Registered in antora-facto by default.

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