Root page

How llms.txt and shared chrome find the page published at each language root: the home page, or a doc-rooted site’s docs section page

Selection rule

_partials/td/root-page.html returns a site’s root page: it takes a Site and returns the page at logical path /docs when the URL of its html output format equals the home page’s, otherwise the home. Consumers share the result through partialCached, which caches per site.

Consumers

llms.txt discovery: the rel="describedby" link in every page head, the in-body agent directive, the Markdown versions’ llms.txt link, and the Docsy-private _root-llms-txt-path shortcode all need the language’s llms.txt URL, which exists when the root page has an LLMS output (Discovery).
The llms.txt template (all.llms.txt):
- The home-page link targets the language’s root page; the Site locales list links each language’s root page.
- The description is the root page’s, falling back to the home page’s.
- The documentation index is a separate /docs lookup.
Shared chrome: in the shared chrome build mode, the navbar and footer are kept on one donor page per language, the root page, and restored from it elsewhere. The chrome applies the definition without the lookup: a page is the donor when its html URL equals the home page’s. The placeholders carry data-chrome-donor, the home page’s html URL, where the client fetches the chrome; the navbar’s also carries data-canonical-path, the page’s own html URL, which keys the client’s active-state restore. The left-nav has a donor rule of its own (donor pages).

Why this rule

Absolute logical path, site.GetPage "/docs": a bare "docs" would be wrong. When there is no /docs section, a Site lookup falls back to a site-wide lookup by name, which fails the build on two pages named docs (page reference "docs" is ambiguous) and silently returns the one such page otherwise (#2875).
The URL comparison keeps an ordinary /docs/ section from being taken for the root.
The html output URL, not the URL of the format being rendered: the cached result serves every render pass, and a permalinkable format can render before HTML.
The home page’s html URL as the reference: Hugo computes it under every URL setting (baseURL paths, language prefixes, multihost, site-wide uglyURLs, the site matrix’s version dimension), which no configuration-derived root reproduces in full.

The docs name is the doc-rooted recipe’s own: the recipe redefines that section’s permalinks, and the llms.txt documentation index lists its subsections. Two alternatives that avoided the name were set aside:

Scanning site.Sections for a section at the home’s URL depends on Hugo’s listing rules: a section page with build.list: never publishes but is not listed.
A configuration switch would duplicate what permalinks already states.

Covered cases

The table records supported behavior; the Evidence column names the fixture test (tests/fixture-site/) exercising the row. Chrome consequences assume shared mode.

Case	Root page and consequences	Evidence
Ordinary site (home renders, docs under `/docs/`)	The home. `llms.txt` at `/llms.txt` when `LLMS` is among the home outputs; the home is the donor page.	`llms-directive`, `chrome-render`
Doc-rooted site	The `docs` section page, published at the home’s URL. Publishes `llms.txt` when its outputs include `LLMS`; it is the donor page.	`llms-doc-rooted`, `chrome-doc-rooted`
No `/docs` section, pages named `docs` elsewhere (one or many)	The home; the build succeeds, and `llms.txt` has no documentation index.	`root-page`
Multilingual project	One root page per language (`/`, `/fr/`), each able to publish its own `llms.txt` and each its own donor page; `defaultContentLanguageInSubdir` only moves the URLs.	`root-page`, `chrome-doc-rooted`
`docs` section page without a translated `_index` file	Hugo’s auto-created section is still the root when published there; its outputs come from configuration or `cascade`, not from a file.	`root-page`
`baseURL` with a subpath	Both compared URLs include the subpath, so the selection is unchanged.	`root-page`
Several output formats (HTML, Markdown, print, RSS, LLMS)	Selection is unchanged whatever format renders first or carries `rel=canonical` (the rule compares `html` URLs). The donor is the root page’s HTML render; its print render gets a placeholder like any other page.	`root-page`, `llms-doc-rooted`, `chrome-doc-rooted` (print), `chrome-render` (permalinkable print)
Site-wide `uglyURLs`	Both compared URLs end in `index.html`, so the selection is unchanged; the donor is named as `/index.html`.	`root-page`
Doc-rooted home with `LLMS` configured	The home publishes no file; root-level `llms.txt` and discovery require `LLMS` on the `docs` section page.	`llms-doc-rooted`
Root page without `LLMS`	No `describedby` link, directive, or Markdown link, even when another section publishes an `llms.txt`; the shortcode fails the build when invoked.	`llms-directive`, `llms-doc-rooted`
`LLMS` on a non-root section	Its `llms.txt` is the site overview, not a section index; discovery still depends on the root page’s `LLMS` output.	`llms-doc-rooted`

Limits

The design leaves these unresolved:

A section other than docs remapped to the site root: the lookup keeps the home, so llms.txt discovery follows the home, while the chrome’s self-test makes that section the donor; Hugo need not warn (a link-only home leaves no duplicate output).
Two pages publishing the same root URL: a path conflict of the site’s own.
A doc-rooted language without a /docs section: it has no root page, so llms.txt lists the language at an unpublished URL, and the site root that shared chrome names as donor serves nothing.
A doc-rooted home whose output formats (site outputs.home, or its own front matter) don’t start with HTML: a link-only page keeps only its first configured format, so the home has no html URL to compare with; the home stays the root page, no render is the donor, and the placeholders name an empty donor (the client fetches the page itself once); llms.txt discovery follows the home’s kept formats, present only when LLMS is among them. The same holds for build.render: never and an empty outputs.home, where llms.txt’s home and locale links are empty too (the docs section page still publishes its llms.txt). Hugo’s outputs convention is HTML first.
A docs section page whose outputs leave out HTML: it is neither selected nor a donor.
uglyURLs set for the docs section only (uglyURLs: { docs: true }): the section page publishes at /index.html while the home page, in no section, keeps /, so the URLs differ and the home stays the root page, with no discovery and no donor.
HTML marked notAlternative: the donor page’s other renders then carry the chrome too (the current-render test is “HTML is not among the alternatives”); the placeholders still name the site root, so the restore works.
A paginated root page: each /page/N/ continuation renders the chrome too. The theme’s own layouts paginate only the blog list.

Dernière modification October 20, 2026: Fix the root-page lookup and the doc-rooted donor page (#2888) (7cfa759)