# 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 **master–detail** — 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).
