Beta shell - Design

Requirements: ./requirements.md
Status: agreed

Approach

The shell is copied from the served beta HTML, not redesigned. shell.html is the

page frame. Features inject HTML into named slots. That is the same split as

GeoNet's border.html plus {{template "body" .}}.

CSS for chrome comes from beta by URL. The kit only adds:

rewritten hero-pattern url()s (beta's are root-relative and 404 here)
empty-sidebar and empty-band collapse
composition-index styles

Slots

Slot	Beta region	Who fills it
`alert`	inside `.alert-container`, after the kit banner	Features that need a notice; 911/notice-bar later
`hero`	`.page-hero-container`	Features that need a page title + callout
`bandBefore`	`.layout-container-band` above the grid	A feature that wants the full page width, beta home-page style
`body`	first column of `.layout-container > .layout-two-col`	Primary feature content
`sidebar`	second column	Optional; hidden when empty (R4)
`bandAfter`	`.layout-container-band` below the grid	As `bandBefore`, after the main content

Header, footer and the kit preview banner are owned by the base. They are not slots.

Bands are wrappers the shell always emits, so any fragment mounted there gets the

full-width row without shaping itself as a band. Unused wrappers are hidden with

:not(:has(*)) rather than :empty, which whitespace would defeat.

Which slot a feature lands in is the composition's call (R10): a feature lists the

slots it can fill and the composition may remap them with at:. Keeping placement

out of the slice is what stops near-duplicate slices whose only difference is where

they sit on a page.

Markup

slices/base/v1/shell.html is the live beta header and footer, with

href="/…" and src="/…" rewritten to https://beta.geonet.org.nz/…. Nav labels

and destinations are not paraphrased.

The kit banner uses beta's .site-alert so it picks up the same type and colour,

with copy that says this is a preview (R7).

Tokens and styling

Linked from beta (R5):

geonet-design-system.css
Aspekta and Soehne
layout.css, page-hero.css, marker.css, home.css

css/base.css is kit-only overrides, not a second design system (R8).

geonet-design-system.mjs is fetched at build time and emitted under /assets/js

so header menus run same-origin (R6).

Accessibility

Header/footer keep beta's structure (aria-controls, inert menus, mobile

menu button).

Kit banner is a heading + sentence, not a live region.
Features still own their own captions, live regions and heading levels. The

shell does not supply an <h1>; the hero slot should.

Handoff notes

shell.html corresponds to border.html in www-geonet / the beta equivalent.
Slot body is the {{define "body"}} block.
Do not send css/base.css to GeoNet; it only exists because we are not on their

origin.

Header/footer markup should be re-copied from beta when they change it, not

drifted by hand.

Rejected alternatives

Invented chrome with "GeoNet Strata" wordmark. Fast, but reviews were of the

kit, not of GeoNet.

Astro/React shell. Cannot lift into Go templates.
Vendoring the design system. Those assets are marked private.
Putting shell requirements in the felt-reports spec. The chrome would churn

with a feature that does not own it.

A base@2 per page layout. Every home-page-shaped or article-shaped variant

would be a new base, and every feature would have to widen requiresBase to be

usable on it. Slots plus composition-level at: cover the same ground on one

base. base@2 is reserved for a breaking change to this contract.

Placement declared in the feature slice. Would force a second slice whenever

the same block appears in a sidebar on one page and a band on another.