docs(spec): frontend SPA milestone 1 (foundation slice) design

Decomposes the admin SPA into milestones; specs M1 — web/ scaffold,
Vite+React+TS+pnpm+shadcn/ui, openapi-typescript+openapi-fetch typed
client, TanStack Query, react-i18next (sv/en), two-pane master-detail
layout, login/session guard, read-only Objects browse, Vitest+RTL+MSW
tests, memory-serve embed behind a feature gate, 150KB bundle budget.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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# Frontend SPA — Milestone 1 (Foundation Slice) — Design
**Date:** 2026-06-03
**Status:** Approved (brainstorming) — ready for implementation planning.
## Context
The backend MVP is code-complete: an authenticated admin HTTP API (object CRUD +
flexible fields, vocabulary/authority/term management, stepwise publishing, search,
audit), a public read API, and a code-first OpenAPI document (utoipa). There is **no
frontend yet**. VISION + `docs/specs/2026-06-02-mvp-architecture.md` §17 call for a
**lean React SPA** in `web/` that consumes the OpenAPI, with sv/en localization and an
explicit "potato hardware" bundle-discipline budget.
The admin UI is a large surface, so it is **decomposed into milestones**, each with its
own spec → plan → implementation cycle:
1. **Foundation slice (this spec):** scaffold, build/dev/serve, typed API client, app
shell (nav + i18n), login/session, and the Objects screen (paginated list +
read-only detail).
2. Object authoring — create/edit/delete + the dynamic flexible-field form driven by
`field-definitions`.
3. Publishing workflow — stepwise draft→internal→public UI with the required-field gate.
4. Vocabulary & authority management.
5. Search UI.
## Goal (Milestone 1)
A walking skeleton that proves the whole pipeline end-to-end — **log in → fetch →
render → embedded in the binary** — and lands a real, usable screen (browse + read
catalogue objects). Every piece of plumbing here is reused by later milestones.
## Decisions (settled during brainstorming)
- **Stack:** React + TypeScript + **Vite**, **pnpm**, **shadcn/ui** components,
**TanStack Query** for server state, **react-i18next** for sv/en.
- **API client (Option A):** `openapi-typescript` generates types from the OpenAPI
JSON; `openapi-fetch` (tiny typed wrapper) for calls; TanStack Query hooks written by
hand. Smallest dependency surface, contract auto-synced, query layer under our control.
- **Layout (Option C):** two-pane **masterdetail** — object list on the left, the
selected record fills the right pane (inspector style; efficient for browse + later
edit-in-place).
- **Testing (Option A):** **Vitest + React Testing Library + MSW** (Mock Service Worker)
— component/hook tests in-process; MSW intercepts fetches with handlers typed against
the generated schema, so tests stay honest to the OpenAPI contract without a browser.
A Playwright e2e smoke is deferred to a later milestone (fits once `--seed` data exists).
- **Bundle budget:** initial JS **≤ 150 KB gzipped**, tracked in CI.
## Scope (YAGNI)
**In:**
- `web/` scaffold + build/dev/serve (incl. release embedding).
- Generated typed API client + TanStack Query hooks.
- App shell: compact icon sidebar (Objects active; later items shown **disabled /
"coming soon"**), top bar with sv/en switch + user menu (logout).
- Auth: login page, logout, session guard.
- **Objects two-pane:** paginated list (left) + **read-only** detail (right) showing the
inventory-minimum fields and flexible-field *values*, with a visibility badge.
**Out (later milestones):** create/edit/delete and dynamic field *forms* (M2), publish
workflow (M3), vocabulary/authority/term management (M4), search UI (M5), media/
thumbnails. Later nav items appear as disabled stubs so the shell's shape is visible.
## Architecture
### Project layout (`web/`)
```
web/
package.json pnpm; scripts: dev, build, test, typecheck, lint, gen:api
vite.config.ts dev proxy /api,/api-docs,/health -> http://localhost:8080
tsconfig.json
index.html
components.json shadcn/ui
src/
main.tsx entry: QueryClientProvider, i18n, router
app.tsx route table
api/
schema.d.ts generated (openapi-typescript) — committed
client.ts openapi-fetch client; credentials:'include'; 401 middleware
queries.ts useMe, useObjectsPage, useObject, useLogin, useLogout
auth/
session.tsx session context (via /api/admin/me); RequireAuth guard
login-page.tsx
shell/
app-shell.tsx icon sidebar + top bar + <Outlet/>
lang-switch.tsx
objects/
objects-page.tsx two-pane container (list + detail by :id)
object-list.tsx
object-detail.tsx
visibility-badge.tsx
i18n/
index.ts react-i18next init
en.json sv.json
components/ui/... shadcn primitives
test/
setup.ts Vitest + RTL + MSW server
handlers.ts MSW handlers typed against schema.d.ts
```
### Serve / build model
- **Dev:** `pnpm dev` runs Vite on `:5173`, proxying `/api`, `/api-docs`, `/health` to
the Rust server on `:8080` (run separately). Session cookies stay same-origin through
the proxy. Backend dev/test loop is unchanged and independent of the frontend.
- **Release:** `pnpm build``web/dist`, embedded into the **`server`** binary via the
**`memory-serve`** crate and served at `/` with an SPA fallback (any non-`/api`,
non-`/health`, non-`/api-docs` path → `index.html` for client-side routing).
- **Feature gate `embed-web`** (off by default) on the `server` crate guards the
memory-serve embedding, so `cargo build`/`cargo test` never require a built `web/dist`.
CI builds the SPA first, then `cargo build -p server --features embed-web` for the
release artifact. **Milestone 1 proves this embed path end-to-end.**
### Data flow
1. App mounts → `useMe()` queries `/api/admin/me`. 200 → session established; 401 → the
client middleware redirects to `/login`.
2. `/objects``useObjectsPage(limit, offset)``GET /api/admin/objects` (the paginated
admin list already built). Left pane renders rows; selecting one routes to
`/objects/:id`.
3. `/objects/:id``useObject(id)``GET /api/admin/objects/{id}`. Right pane renders
inventory-minimum fields + flexible-field values + visibility badge; 404 → not-found
state.
4. Login: `useLogin``POST /api/admin/login` (session cookie set); on success invalidate
`useMe` and navigate to `/objects`. Logout: `POST /api/admin/logout` → clear → `/login`.
### Routing
| Path | Access | Renders |
|------|--------|---------|
| `/login` | public | login page (redirects to `/objects` if already authed) |
| `/` | protected | redirect → `/objects` |
| `/objects` | protected | two-pane; empty right pane prompt |
| `/objects/:id` | protected | two-pane; right pane = record |
| `*` | protected | redirect → `/objects` |
`RequireAuth` wraps protected routes; unauthenticated → `/login`.
## Error / loading / empty states
- **List:** loading skeleton; empty ("no objects yet"); error with retry.
- **Detail:** loading; 404 not-found; error with retry.
- **Login:** inline invalid-credentials (401) and network-error messages.
- **Visibility:** i18n'd badge — draft (neutral) / internal (amber) / public (green).
- All user-facing copy lives in `en.json` + `sv.json`; language switch persists to
`localStorage`.
## Testing & CI
- **Vitest + RTL + MSW.** `test/setup.ts` starts an MSW server; `handlers.ts` returns
realistic responses typed against `schema.d.ts`. Coverage for M1:
- API client + query hooks (success + error mapping).
- Login flow: success → navigates; 401 → inline error.
- Objects list: renders rows, pagination controls, empty + error states.
- Object detail: renders fields + visibility; 404 state.
- Language switch toggles copy.
- `RequireAuth` redirects unauthenticated users to `/login`.
- **CI (new `web` job):** `pnpm install``tsc` typecheck → eslint → `vitest run`
`vite build`**bundle-size check (initial JS ≤ 150 KB gz)**.
## Acceptance criteria (Milestone 1 "done")
1. `pnpm dev` + the running server: can log in, see a paginated object list, select a
row, read its detail (incl. flexible-field values), switch sv/en, and log out.
2. Unauthenticated access to a protected route redirects to `/login`; a 401 mid-session
bounces to `/login`.
3. `cargo build -p server --features embed-web` (after `pnpm build`) produces a binary
that serves the SPA at `/` with working client-side routing; backend `cargo test`
still passes **without** a built frontend.
4. `web` CI job green: typecheck, lint, tests, build, bundle-size within budget.
5. Later nav items are visible but disabled.
## Out of scope / follow-ups
- Playwright e2e smoke (later milestone, once `--seed` data exists; relates to issue #14).
- Object create/edit/delete + dynamic field forms (Milestone 2).
- Any write operations from the UI (M1 is read-only beyond auth).