summercms/docs/backend/admin-spa.md

title, description, section, order

title	description	section	order
Admin SPA	How boardwalk serves the embedded Vue admin SPA under backend.uri, how the SPA talks to the admin API, and how its TypeScript types come from OpenAPI.	backend	80

Admin SPA

WinterCMS renders its backend on the server with layouts, partials and the AJAX framework. SummerCMS replaces that with one Vue 3 single-page app, built once and embedded in the binary by boardwalk. Plugins do not ship admin pages: they ship YAML and, when they need them, partials and scripts, and the SPA renders every controller from the schemas the admin API serves.

Serving

cabana mounts the SPA under the admin prefix, backend.uri (/backend by default; one or more lowercase path segments). boardwalk.Handler serves the build:

• Any path under the prefix that is not a file and not under api/ returns index.html, so the SPA's own routes work on reload.
• Paths under api/ that no API route matches return the admin API's JSON not_found error, never the SPA.
• Hashed files under assets/ are cached for a long time; index.html is never cached.
• Every response carries a restrictive Content-Security-Policy, frame denial, nosniff, a same-origin referrer policy and noindex, nofollow.

The build is path-agnostic: index.html holds a placeholder (boardwalk.BaseToken) that boardwalk.RewriteIndex replaces with the prefix once, when the handler is built. A build without the placeholder fails the start-up.

A plugin route under the admin prefix also fails the start-up: the SPA and the admin API own that whole path.

How the SPA talks to the server

The SPA signs in through the admin API and keeps the token in the HttpOnly cookie described on Users and permissions. For each screen it loads the controller's localized schema (schema/list, schema/form), then the records, and renders the fields and columns the schema names. Strings come from GET <prefix>/api/v1/lang, the backend::lang bundle in the request locale, with CLDR plural forms.

Each record form makes a session key when it opens: 32 random bytes, base64url encoded. The form sends it in the X-Session-Key header with every file upload, file list and file removal, and with the final create or update save. Uploads and removals are deferred: the server holds them against the key and the admin, and the save that carries the same key commits them in its transaction. Until then the form counts as unsaved, so leaving it asks first, and a new record's files go to record id 0. The form will not save while an upload is still in flight. Uploads use XMLHttpRequest for progress events and carry the same X-Requested-With header and cookie as every other call, plus an X-Upload-Id so a retry returns the already stored file. Files of a protected relation are fetched through the admin API with the key and shown from object URLs. The key travels only in headers, never in a URL. See File uploads for the fileupload field.

Types from OpenAPI

The admin API is described by swag annotations in cabana. scripts/check-admin-openapi.sh generates the OpenAPI document (admin/openapi/admin.json) from them and the SPA's TypeScript types (admin/src/api/schema.d.ts) from the document, so the SPA's API client is checked against the server's shapes at compile time. --check fails when either committed file is out of date:

scripts/check-admin-openapi.sh --check

Building the SPA

The SPA's source is the admin/ Vite project. npm --prefix admin run build type-checks it and writes the build to modules/boardwalk/dist, which the next go build embeds. An application that only uses the framework never builds the SPA: the build is committed with the framework.