# Website RSC Presentation Architecture (Strict)

This document defines the only allowed presentation architecture for `apps/website` (Next.js App Router).

It is **website-only** and does not change `apps/api` or `core` architecture.

Authoritative contract: [`WEBSITE_CONTRACT.md`](docs/architecture/website/WEBSITE_CONTRACT.md:1).

## 1) Core rule: API owns business truth

- `apps/api` is the only source of truth for business rules and canonical filtering/sorting.
- `apps/website` is presentation infrastructure: composition, routing, caching, and rendering.

## 2) The three website presentation data types

### 2.1 Page DTO

**Purpose:** server-to-client payload.

**Rules:**

- JSON-serializable only.
- Contains raw values only (ISO date strings, numbers, codes).
- MUST NOT contain class instances.

### 2.2 ViewModel

**Purpose:** client-only presentation model.

**Rules:**

- Class-based.
- Instantiated only in `'use client'` modules.
- Composes Display Objects.
- NEVER passed into Templates.

### 2.3 ViewData

**Purpose:** Template input.

**Rules:**

- JSON-serializable only.
- Contains only values ready to render (mostly strings/numbers).
- Built from Page DTO (initial render) and from ViewModel (post-hydration).

The mapping between Page DTO, ViewModel, and ViewData is performed by Presenters.
See [`PRESENTERS.md`](docs/architecture/website/PRESENTERS.md:1).

## 3) Required per-route structure

Every route MUST follow:

1) `page.tsx` (server): calls a PageQuery and passes Page DTO
2) `*PageClient.tsx` (client): builds ViewData and renders Template
3) `*Template.tsx` (pure UI): renders ViewData only

All writes enter through Server Actions.
See [`FORM_SUBMISSION.md`](docs/architecture/website/FORM_SUBMISSION.md:1).

## 4) Authoritative specification

This document is an entry point only.

The authoritative, test-enforced spec lives at:

- [plans/nextjs-rsc-viewmodels-concept.md](plans/nextjs-rsc-viewmodels-concept.md:1)

Final contract:

- [`WEBSITE_CONTRACT.md`](docs/architecture/website/WEBSITE_CONTRACT.md:1)