docs

docs/architecture/website/PRESENTERS.md

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+# Presenters (Strict)
+
+This document defines the **Presenter** boundary for `apps/website`.
+
+Presenters exist to prevent responsibility drift into:
+
+- server routes
+- Page Queries
+- Templates
+
+## 1) Definition
+
+A **Presenter** is a deterministic, side-effect free transformation between website presentation models.
+
+Allowed transformations:
+
+- Page DTO → ViewData
+- Page DTO → ViewModel
+- ViewModel → ViewData
+
+## 2) Non-negotiable rules
+
+1. Presenters MUST be deterministic.
+2. Presenters MUST be side-effect free.
+3. Presenters MUST NOT perform HTTP.
+4. Presenters MUST NOT call API clients.
+5. Presenters MUST NOT access cookies/headers.
+6. Presenters MAY use Display Objects.
+7. Presenters MUST NOT import Templates.
+
+## 3) Where Presenters run
+
+Presenters run in **client code only**.
+
+Presenters MUST be defined in `'use client'` modules.
+
+If a computation affects routing decisions (redirect, notFound), it belongs in a Page Query or server route composition, not in a Presenter.
+
+## 4) Relationship to Display Objects
+
+Display Objects implement reusable formatting/mapping.
+
+Rules:
+
+- Presenters may orchestrate Display Objects.
+- Display Object instances MUST NOT appear in ViewData.
+
+See [`DISPLAY_OBJECTS.md`](docs/architecture/website/DISPLAY_OBJECTS.md:1) and [`VIEW_DATA.md`](docs/architecture/website/VIEW_DATA.md:1).
+
+## 5) Canonical placement in this repo (strict)
+
+Presenters MUST live colocated with ViewModels under:
+
+- `apps/website/lib/view-models/**`
+
+Reason: this repo already treats `apps/website/lib/view-models/**` as the client-only presentation module boundary.