vue-menu-layer/README.md

# vue-menu-layer

A Nuxt 4 layer that renders a menu of the SummerCMS menu plugin as an accessible site navigation.

```bash
pnpm add git+https://git.golem15.com/golem15/vue-menu-layer.git#v0.2.0
```

## Overview

The layer is consumed with `extends: ['vue-menu-layer']`. It reads one route of the menu plugin's anonymous API, `GET /_menu/api/v1/menus/{code}`, during SSR, so the first paint already has the menu, and renders it with `<MenuNav code="…">`. Editors manage menus in the SummerCMS admin; the site needs no menu data of its own.

The layer is neutral: it ships no site colours, no site copy and no Nuxt modules. Its look comes from `--menu-*` CSS custom properties, which an app overrides, and every component can be replaced by a file of the same name in the app.

## Features

- **`MenuNav`**: a `<nav>` with the menu's `css_class`, a list of entries, and a 44×44 mobile toggle below 768px. Fetched during SSR through `useAsyncData` (key `menu:<code>:<locale>`).
- **Disclosure navigation** (WAI pattern): an entry with children and a URL keeps its link and gets a sibling toggle button with `aria-expanded` and `aria-controls`; an entry with children and no URL (or the placeholder `#`) is one toggle button. Submenus open on click, and on hover for hover-capable pointers on the desktop layout; Esc (focus returns to the toggle), focus leaving the entry, a pointer-down outside the nav and every route change close them. Opening one submenu closes its open siblings.
- **Links**: a site path renders as `NuxtLink`; an absolute, `mailto:`, `tel:` or `#fragment` URL as a plain anchor. A URL outside the allowlist (`http`, `https`, `mailto`, `tel`, a leading `/` or `#`) renders as `<span class="menu-nav__text">` without an `href`, even though the API already refuses such URLs. A `_blank` link carries `rel="noopener noreferrer"`.
- **Active state**: the entry whose URL path equals the current route path (decoded, query, hash and trailing slash ignored; an absolute URL only on the request host) gets `aria-current="page"` and `menu-nav__link--active`; its ancestors get `menu-nav__item--trail`.
- **Dividers**: `aria-hidden` list items, a horizontal line in panels and a short vertical line at the top level on the desktop.
- **Empty states**: a missing menu (404), a failed request or a menu without entries renders nothing, or the `#fallback` slot. There is never an empty `<nav>`.
- **Site cache purge**: the shared route `POST /api/__site__/cache/purge` drops the site's route cache when the backend saves, deletes or reorders a menu or menu entry (or a FAQ or post, through the other core layers). See [Site cache purge](#site-cache-purge).
- **Rate limits**: server-side fetches forward the visitor's `x-forwarded-for` (also on route-cached renders), so the API's per-client throttle sees visitors, not the Nuxt server.

## Usage

```ts
// nuxt.config.ts of the app
export default defineNuxtConfig({
  extends: ['vue-menu-layer'],
  runtimeConfig: {
    menu: { apiBase: 'http://127.0.0.1:8096/_menu/api/v1' }, // NUXT_MENU_API_BASE
  },
})
```

```vue
<MenuNav
  code="main"
  label="Main menu"
  open-label="Open menu"
  close-label="Close menu"
  submenu-label="Show submenu: :title"
/>
```

| Prop | Default | Meaning |
|---|---|---|
| `code` | required | The menu code. |
| `locale` | the API's default locale | Sent as `?locale=`; picks the locale alternates of resolved entries. |
| `label` | the menu code | `aria-label` of the `<nav>`. |
| `openLabel` / `closeLabel` | `Open menu` / `Close menu` | Visually hidden text of the mobile toggle. |
| `submenuLabel` | `Show submenu: :title` | Visually hidden text of a submenu toggle next to a link; `:title` is the entry title. |

Slots:

- `#item="{ entry, depth, active }"`: the content of an entry's link, button or text, for example to render the API's `icon`, which the layer does not render.
- `#fallback`: rendered instead of the nav when there is no menu to show.

`useMenu(code, { locale })` returns the `useAsyncData` result (`data` is `null` for a missing menu) for an app that renders the menu its own way; `useMenuApi()` returns the typed client.

## Configuration

| Key | Default | Environment |
|---|---|---|
| `runtimeConfig.menu.apiBase` | `http://127.0.0.1:8096/_menu/api/v1` | `NUXT_MENU_API_BASE` (server only, used for SSR) |
| `runtimeConfig.public.menu.apiBase` | `/_menu/api/v1` | `NUXT_PUBLIC_MENU_API_BASE` (browser, same origin) |
| `runtimeConfig.siteCache.purgeToken` | `''` (route off) | `NUXT_SITE_CACHE_PURGE_TOKEN` (server only; at least 32 characters) |

The base URLs always come from runtime config, never from request input. In production the web server routes `/_menu/` to the SummerCMS binary.

## Site cache purge

A site that route-caches its pages (for example `routeRules: { '/**': { swr: 300 } }`) shows an admin edit only when the cache window ends. The layer ships the shared purge route that the SummerCMS backend calls after an admin save commits:

```
POST /api/__site__/cache/purge
Authorization: Bearer <NUXT_SITE_CACHE_PURGE_TOKEN>
{"kind":"menu_entry","slug":"partition:3"}
→ {"purged": <n>}
```

- It removes every entry of Nitro's route cache (pages, their `_payload.json` and feeds) and logs `[site-cache] purge: …` with the kind and slug.
- Set `NUXT_SITE_CACHE_PURGE_TOKEN` to the backend's `site_cache.purge_token` (at least 32 characters) and point the backend's `site_cache.purge_url` at `http://127.0.0.1:<port>/api/__site__/cache/purge`. Without a token of that length the route answers 404.
- It answers 404 to any request that came through a reverse proxy (`X-Forwarded-For`, `X-Real-IP` or `Forwarded`), so only the backend on the same machine reaches it, and 401 to a missing or wrong bearer token (compared in constant time).
- The layer adds the route rule `'/api/__site__/**': { cache: false }`; without it, a site-wide `swr` rule would answer the purge from the cache.
- vue-journal-layer, vue-menu-layer and vue-faq-layer ship the same `server/lib/siteCachePurge.ts` and `server/api/__site__/cache/purge.post.ts` byte for byte (a test pins their sha256), so a site that extends several of them gets one route, whichever copy Nitro keeps.

## API

The layer expects the menu plugin's public API:

```json
GET /_menu/api/v1/menus/main?locale=en
{"data":{"code":"main","name":"Main","css_class":null,"items":[
  {"id":1,"title":"Home","type":"url","url":"/","target":"_self","css_class":null,"icon":null,"code":"home","items":[]},
  {"id":3,"title":"Pages","type":"acme-list","url":"/pages","target":null,"css_class":null,"icon":null,"code":null,"items":[
    {"id":null,"title":"About","type":"acme-list","url":"/about","target":null,"css_class":null,"icon":null,"code":null,"items":[]}]},
  {"id":5,"title":"","type":"divider","url":null,"target":null,"css_class":null,"icon":null,"code":null,"items":[]}]}}
```

An unknown or inactive menu answers `404 {"error":"Menu not found"}`. The types are in `app/utils/types.ts` (`Menu`, `MenuEntry`).

## Theming

Override tokens on `:root:root` (higher specificity than the layer's `:root`, independent of CSS order):

```css
:root:root {
  --menu-color-accent: #2f6b3a;
  --menu-font: 'Jost', sans-serif;
}
```

| Group | Tokens |
|---|---|
| Colour | `--menu-color-text`, `--menu-color-muted`, `--menu-color-bg`, `--menu-color-surface`, `--menu-color-border`, `--menu-color-accent` |
| Type | `--menu-font`, `--menu-font-size`, `--menu-line-height` |
| Spacing | `--menu-space-1` … `--menu-space-4` |
| Radii | `--menu-radius`, `--menu-radius-panel` |
| Layout | `--menu-submenu-min-width`, `--menu-toggle-size` |
| Shadow | `--menu-shadow` |

The mobile breakpoint (767px) is fixed in `menu-base.css`, because custom properties cannot drive media queries. The mobile panel is positioned against the nearest positioned ancestor (a sticky header, for example).

To replace a component, add a file with the same path in the app, for example `app/components/Menu/NavItem.vue`.

## Local development

```bash
pnpm install
pnpm dev               # the playground in .playground/
```

## Releasing

Commit, tag `vX.Y.Z` (annotated) and push the tag; apps pin `#vX.Y.Z` in their dependency.

## Testing

```bash
pnpm test                                   # node --test: link rules, client, rendered NavItem markup, site cache purge
pnpm build:playground && pnpm smoke:ssr     # SSR of the playground against testing/fixture-api.mjs
```

`tests/render.ts` compiles `Menu/NavItem.vue` with Vue's SFC compiler and renders it on the server, so the URL allowlist and `rel` rules are asserted on the markup.