docs(adr): record React/Vite admin decision as ADR-008

Commits ADR-008 (React/Vite admin) for [E01-S01-T07], with the six mandated
sections (Context, Decision, Alternatives, Consequences, Operational impact,
Revisit trigger) per ADR index 46, and adds docs/adr/README.md as the
repository copy of the ADR index (section 70) so the decision-text match is
verifiable inside the repo. Documentation-only: no source, manifest,
lockfile, workflow or test changes.

docs/adr/ADR-008-react-vite-admin.md

@@ -0,0 +1,136 @@
+# ADR-008: React/Vite admin
+
+- Status: Accepted
+- Date: 2026-08-31
+- Deciders: platform stream
+- References: ADR index (section 70, `docs/adr/README.md`), ADR-001, ADR-007,
+  Architecture wiki (sections 1, 4, 9, 11, 20, 42), Technology-Stack wiki
+  (sections 5.2, 5.3, 6, 7, 8)
+
+## Context
+
+EPPP is a modular monolith (ADR-001) whose single application image contains the
+public server, admin API, rendering pipeline, extension runtime, core services,
+built admin assets and first-party extensions (Architecture §4). The v0.1 scope
+explicitly includes an "administration interface" (§1), and Architecture §20
+already fixes its shape: a **React client app built with Vite**, served by the
+same image, with `/admin/*` talking to the admin API under `/api/admin/v1/*` and
+an initial IA of Dashboard, Content→Posts, Home, Navigation, Appearance (active
+theme, theme settings), Extensions and Settings→Site. ADR-001 fixes the runtime
+as "Node.js 24 LTS with Fastify 5, PostgreSQL 18, React 19 for server-rendered
+public components and a Vite admin".
+
+React and Vite are already the pinned toolchain in the golden compatibility
+tuple. React / React DOM 19.2.8 (class C, exact-pinned) is in the runtime stack
+and golden tuple (Technology-Stack §5.2, §7), and the build/admin/test toolchain
+is pinned to Vite 8.2.2, `@vitejs/plugin-react` 6.1.0, pnpm 11.23.0, Vitest
+4.1.10 and Playwright 1.62.1 (§5.3). The LTS strategy keeps React exact-pinned
+at 19.2.8, keeps React Server Components out of v1 and keeps React out of
+persisted content formats (§6); direct platform dependencies are exact-pinned
+with a committed lockfile (§8).
+
+The workspace does not implement the admin app yet — `apps/server` is the bare
+Fastify health shell and there is no `apps/admin` (Architecture §9; the CI
+`build-apps` stage already globs `apps/**` so the admin is picked up when it
+lands). This ADR therefore records the decision ahead of the code that
+implements it, formalising what the Architecture and Technology-Stack wikis
+already mandate: the admin frontend is a React client app built with Vite and
+served by the same application image.
+
+## Decision
+
+EPPP builds the admin frontend with **React/Vite admin**: a React client
+application built with Vite — React 19.2.8 and Vite 8.2.2, exact-pinned class C
+dependencies from the golden compatibility tuple (Technology-Stack §5.2, §5.3,
+§7) — served by the same application image (ADR-001, Architecture §4). The admin
+lives under `/admin/*` and calls the admin API at `/api/admin/v1/*` (§20, §42).
+It is deliberately a separate concern from the public rendering pipeline:
+public pages stay server-rendered with no client hydration (ADR-007, §19.1),
+while the admin is a client-rendered SPA — the interactive management surface
+where JavaScript is expected and required. React Server Components stay out of
+v1 and React stays out of persisted content formats (Technology-Stack §6).
+The decision text — **React/Vite admin** — matches the ADR index entry
+(ADR-008, section 70).
+
+## Alternatives
+
+- **Server-rendered admin through the public React SSR pipeline** — rejected:
+  the admin is an interactive management surface where JavaScript is expected;
+  routing it through the zero-JavaScript, non-hydrated SSR pipeline (ADR-007,
+  §19.1) would buy nothing — every admin page needs client interactivity — and
+  would couple admin rendering to the public pipeline's per-request server
+  rendering.
+- **Separate admin framework (e.g. Next.js, Angular, Vue SPA)** — rejected: the
+  golden tuple pins React 19.2.8 (Technology-Stack §5.2, §7) and ADR-001 already
+  records "a Vite admin"; a second frontend ecosystem would split the admin UI
+  from the public components with no v1 requirement justifying it.
+- **Framework-less Vite / hand-rolled DOM** — rejected: the admin IA (§20) needs
+  a component model for the content, theme, extension and settings screens;
+  re-implementing state management and composition by hand duplicates what React
+  already provides, and the golden tuple already pins React.
+- **Build-time static-site-generated admin** — rejected: the admin is an
+  authenticated, connection-backed interface over the canonical database
+  (ADR-005, ADR-019); build-time HTML would go stale against the canonical DB
+  and add a rebuild/redeploy cycle per content change.
+- **Admin as a separate service or image** — rejected: ADR-001 fixes one
+  application image containing built admin assets; a separate admin deployment
+  would break the single-deployable-unit model and add service boundaries with
+  no v1 benefit.
+
+## Consequences
+
+- Positive: one frontend technology — React 19.2.8 — spans the public SSR
+  pipeline (ADR-007) and the admin SPA, so patterns, components and the golden
+  tuple pin are shared; Vite gives fast HMR during admin development and a
+  static build that ships inside the same image (ADR-001); the admin is
+  explicitly outside the public zero-JavaScript baseline (§19.1), so its
+  interactivity does not conflict with the public surface; the exact-pinned
+  toolchain (Vite 8.2.2, React 19.2.8, committed lockfile) keeps admin builds
+  reproducible under the ADR-026 upgrade lanes.
+- Negative: the admin ships client JavaScript and a client runtime to
+  authenticated admin users; a client-side build step joins the CI pipeline
+  (the `build-apps` stage globs `apps/**`) and brings its own test tooling
+  (Vitest, Playwright — Technology-Stack §5.3, §7); two rendering paths — public
+  SSR and admin SPA — must be maintained, and the client/server contract at
+  `/api/admin/v1/*` must stay versioned; the admin is an authenticated security
+  surface (opaque DB-backed sessions, ADR-019) that the security baseline must
+  keep covering (CSRF, session handling, authz).
+- Neutral: Vite is a build-time detail — what ships is static assets served
+  behind `/admin/*` from the same image; the decision constrains the later
+  client-side decisions (zero-JS public baseline and the client-island model,
+  ADR-009 and ADR-010) to the public surface, not the admin.
+
+## Operational impact
+
+- `apps/admin` builds with Vite into static assets that are served by the same
+  application image behind `/admin/*` (Architecture §20); there is no separate
+  admin service, container or deployment (ADR-001).
+- `/admin/*` serves the SPA shell; the SPA reads and writes through the admin
+  API at `/api/admin/v1/*` (§42), secured by the Fastify lifecycle and opaque
+  DB-backed sessions (ADR-019).
+- The admin build runs in the CI `build-apps` stage — the pnpm `apps/**` glob
+  picks `apps/admin` up automatically when the app lands — and admin behaviour
+  is covered by Vitest unit suites and Playwright e2e (Technology-Stack §5.3,
+  §7).
+- Admin traffic is authenticated and internal; the admin is not part of the
+  public zero-JavaScript surface (§19.1) — client JavaScript is expected and
+  required there — so no byte-budget applies to admin assets.
+- The admin is not implemented yet — today rollback is reverting this
+  documentation commit; once the admin lands, rollback is redeploying the
+  previous image (built admin assets live inside the image, so there is no
+  separate asset deploy to coordinate).
+
+## Revisit trigger
+
+- Revisit when the admin grows a requirement the React/Vite SPA model cannot
+  meet — for example a genuinely different client architecture or offline
+  capability — with evidence per the architecture review gates (ADR index
+  section 68).
+- Revisit when the golden tuple moves React or Vite to a new major — an
+  ADR-recorded upgrade program item (Technology-Stack §7/§8, ADR-026 lane) — or
+  changes the React pin's support class.
+- Revisit when the public client-side decisions (ADR-009, ADR-010) change the
+  boundary between the public surface and the admin, or the admin API contract
+  at `/api/admin/v1/*` needs a different shape.
+- Revisit when the single-image model (ADR-001) changes such that built admin
+  assets must be served or deployed separately.

docs/adr/README.md

@@ -0,0 +1,65 @@
+# ADR index (§70)
+
+Repository copy of the ADR index from the wiki ADR-Index page (§70): the
+canonical list of architectural decisions, committed or planned. Every ADR
+committed to `docs/adr/` must record a decision that matches its row in
+section 70; the wiki page remains the canonical index.
+
+| ADR | Decision |
+|---|---|
+| ADR-001 | Modular monolith |
+| ADR-002 | Node.js 24 LTS runtime |
+| ADR-003 | TypeScript 6.0.3 pending TS7.1 ecosystem review |
+| ADR-004 | Fastify 5 HTTP runtime |
+| ADR-005 | PostgreSQL 18 sole canonical DB |
+| ADR-006 | Kysely contained inside DB adapter |
+| ADR-007 | React SSR for public rendering |
+| ADR-008 | React/Vite admin |
+| ADR-009 | Zero-JS public baseline |
+| ADR-010 | Client-island model for optional public interactivity |
+| ADR-011 | JSON Schema + TypeBox + Ajv validation |
+| ADR-012 | EPPP Extension API hides framework internals |
+| ADR-013 | Node/Amber is a theme extension |
+| ADR-014 | Blog is a first-party content extension |
+| ADR-015 | Versioned block documents |
+| ADR-016 | Versioned page composition |
+| ADR-017 | Extension-owned migrations/tables |
+| ADR-018 | Docker Compose primary installation |
+| ADR-019 | Opaque DB-backed admin sessions |
+| ADR-020 | Separate anonymous preference identity |
+| ADR-021 | Local media storage through storage port |
+| ADR-022 | PostgreSQL jobs before external broker |
+| ADR-023 | No Redis initially |
+| ADR-024 | No microservices initially |
+| ADR-025 | Trusted build-time executable extensions in v1 |
+| ADR-026 | Exact dependency pinning + controlled upgrade lanes |
+| ADR-027 (v1.1) | `core.markdown` block restores Markdown authoring inside the block model |
+| ADR-028 (v1.1) | Hardened outbound fetch as a core service; extensions never fetch directly |
+| ADR-029 (v1.1) | Embed provider allowlist enforced in renderer and generated CSP |
+| ADR-030 (v1.1) | Native server-side SVG charts and diagrams with an accessibility contract |
+| ADR-031 (v1.1) | Theme renaming replaces trademark references |
+| ADR-032 (v1.1) | Day-one byte budgets; latency targets from measurement |
+
+Every ADR contains: Context, Decision, Alternatives, Consequences, Operational
+impact, Revisit trigger (§46 E01-S01).
+
+## Architectural fitness tests (§71)
+
+- **Add Ledger/Paper:** create `theme-paper` extension → register
+  manifest/tokens/assets → optionally override renderer slots → tests →
+  include in build. Failure = editing Home/Post domain, core DB, auth, or
+  `if (theme === "paper")` in core.
+- **Add Reading:** create `org.eppp.reading` → migrations → public route →
+  admin contribution → Home section → settings → job(s) → content/block
+  contributions. Failure = core learning seam/half-life/bookmark/link-health
+  semantics.
+
+## Architecture review gates (§68)
+
+Gate A (end Sprint 1): publish a real post without core becoming
+blog/Amber-specific. Gate B (end Sprint 3): add a Home feature as an extension
+with no core edits. Gate C (end Sprint 4): a radically different theme runs
+without changing content/business logic. Gate D (end Sprint 5): visitor
+preference persists without coupling to auth or theme storage. Gate E (before
+public SDK): Extension API v1 proven enough to maintain. Gate F (Reading):
+Reading owns its whole domain without `if (readingEnabled)` in core.