Edwin van den Houdt
64385999eb
Checkpoint of in-progress work: the registration wizard (address prefill, DUO diploma lookup, policy questions), decision-DTO contracts, parse-don't- validate value objects, infrastructure adapters, plus CLAUDE.md and the architecture/ADR docs. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
124 lines
6.8 KiB
Markdown
124 lines
6.8 KiB
Markdown
# CLAUDE.md
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Agent guide for this repo. The *why* lives in `docs/ARCHITECTURE.md` and
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`docs/architecture/0001-bff-lite-decision-dtos.md`; this file is the *rules*.
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When a decision below and those docs disagree, the docs win — update this file.
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POC of a Dutch BIG-register self-service portal (healthcare professionals log in,
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view their registration, apply for re-registration). Angular 22, standalone,
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signals. No real backend/auth — static mock JSON + fake timers.
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## Commands
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```bash
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npm start # ng serve → http://localhost:4200
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npm test # vitest
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npm run build # ng build (must stay green)
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npm run storybook # component library by atomic layer
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```
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`.npmrc` sets `legacy-peer-deps=true` (Storybook's peer range lags Angular 22).
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Do not run `npm audit fix --force` — it downgrades Angular 22→21. Dev-only
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advisories are pinned via `package.json` `overrides`; the shipped bundle audits clean.
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## The decisions (non-negotiable working agreements)
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### 1. DDD: contexts then layers, dependencies point inward
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`src/app/<context>/<layer>/`. Contexts: `shared`, `auth`, `registratie`,
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`herregistratie`, `showcase` (teaching page, not a feature).
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| Layer | Job | Angular allowed? |
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|---|---|---|
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| `domain/` | business rules + data types | **No — pure TS.** Has `.spec.ts` |
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| `application/` | coordinate state/tasks (stores, commands) | yes (signals) |
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| `infrastructure/` | where data comes from (HTTP adapters) | yes (HTTP) |
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| `contracts/` | wire DTOs (the FE⇄BE seam) | no |
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| `ui/` | how it looks (components, pages) | yes |
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**Dependencies only point inward**: `ui → application → domain`; everyone may use
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`shared`; never the reverse. Cross-context only `herregistratie → registratie → shared`,
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`auth → shared`. Imports use aliases as direction statements: `@shared/* @auth/*
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@registratie/* @herregistratie/*`. `domain/` imports nothing from Angular.
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### 2. Atomic design: folder = layer
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`shared/ui` atoms → molecules → organisms; `shared/layout` templates (`shell`,
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`page-shell`); context `ui/` pages. Each level only uses levels below. A new page
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should be **composition of existing blocks** — adding building blocks is the
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exception, not the default. Atoms are thin wrappers over Utrecht/RHC CSS classes;
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we own only a small typed `input()` API, the design system does the visuals.
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### 3. State: make illegal states unrepresentable
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Default reflex — **if you're about to add a second/third boolean to track state,
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model a discriminated union instead.** Three tools, all in `shared/application`:
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- **`RemoteData<E,T>`** (`remote-data.ts`) — `Loading | Empty | Failure{error} | Success{value}`.
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Combine sources with `map`/`map2`/`map3`/`andThen` (Failure > Loading > Success).
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Render it via the `<app-async>` molecule (`shared/ui/async`) — one of four
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templates, mutually exclusive by construction. Default loading spinner/skeleton
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is delay-gated (~250ms) so fast connections don't flash.
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- **Elm-style store** (`store.ts` → `createStore(initial, reduce)`) — all state in
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one Model; change only by `dispatch(msg)` → **pure** `reduce(model, msg)`. Models
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are tagged unions (see `herregistratie.machine.ts`, `intake.machine.ts`). Templates
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send messages, never mutate.
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- **`Result<E,T>` + value objects** ("parse, don't validate") — raw input becomes a
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branded type only via a parser returning `Result` (`registratie/domain/value-objects/`:
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`Postcode`, `Uren`, `BigNummer`). Once you hold the type, never re-check it.
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**Derive, don't store** what you can compute — e.g. the wizard's visible steps are
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`visibleSteps(answers)`, not a stored field (`intake.machine.ts`).
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**Side effects stay out of the reducer.** A *command* (`application/submit-*.ts`)
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does the HTTP, then dispatches a message describing the outcome. Reducer = "what the
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new state is"; command = "go do it, then say what happened."
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**Shared cross-page state = one root singleton.** Stores are `providedIn: 'root'`
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(`BigProfileStore`, `SessionStore`). That single instance is the shared state — no
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NgRx, no extra lib. Optimistic update pattern: `begin*` (flip pending) →
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`confirm*` (clear + `resource.reload()`) / `rollback*` (undo).
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### 4. BFF-lite + decision DTOs (ADR-0001)
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`infrastructure/` is the **only** layer that touches the network — the
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anti-corruption boundary. Each screen gets one screen-shaped endpoint returning a
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decision-enriched DTO; **the FE renders decisions, it does not recompute business
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rules.** Per rule, pick: *decision flag* (server computes the boolean — e.g.
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herregistratie eligibility) or *config value* (server sends threshold, FE applies
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for instant feedback, server re-validates as authority — e.g. scholing threshold).
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FE keeps only **format** validation, never as authority.
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DTO lives in `contracts/`; a hand-written `parse*`/`toDomain` in `infrastructure/`
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validates the untrusted shape and maps DTO → domain. Wiring a real .NET backend
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touches only `infrastructure/` + `contracts/` (see ARCHITECTURE §6). Server-owned
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rules stay in `domain/*.policy.ts` as reference impl + unit test, marked server-owned,
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but the FE doesn't call them.
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### 5. Testing
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Vitest. Co-locate `*.spec.ts` next to the unit. **Domain and pure logic must have a
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spec** (reducers, combinators, `visibleSteps`, parsers, boundary `parse*` adapters).
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Test the pure function directly — no Angular TestBed for domain. UI is exercised via
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Storybook stories (`*.stories.ts` co-located, titled `Layer/Name`, a11y addon on),
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not heavy component tests.
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## Conventions
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- Standalone components only; no NgModules. Signal inputs (`input()`), `inject()` over
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constructor DI (constructor only for `effect()`/template-ref injection).
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- Angular-native control flow `@if/@for`; native `httpResource` for fetching;
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`withViewTransitions()` for page transitions (header/footer have stable
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`view-transition-name`, excluded from the fade).
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- Routes: lazy `loadComponent`, persistent `ShellComponent` parent, `canActivate:
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[authGuard]` on protected routes (`app.routes.ts`).
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- Theming is one import — `src/styles.scss` pulls the RHC palette; no hand-written theme.
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- Scenario toggle: `?scenario=slow|loading|empty|error` on data pages
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(`scenario.interceptor.ts`) to see every async state.
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- Prettier; `.editorconfig`. tsconfig: `noImplicitReturns`,
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`noPropertyAccessFromIndexSignature`, `noFallthroughCasesInSwitch`, `isolatedModules`.
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## Adding a feature (recipe)
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Domain first (types + pure rules + spec, no Angular) → infrastructure (adapter:
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`httpResource` or command returning `Result`) → application (store if shared state;
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union + pure reduce) → UI last (compose `shared/ui` atoms, wrap async in `<app-async>`,
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dispatch messages). Worked example: the intake wizard (`herregistratie/`).
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## Out of scope (POC, don't build unprompted)
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Real auth/DigiD, real backend, i18n, NgRx, licensed Rijkshuisstijl font/logo,
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runtime DTO validation on every endpoint, multi-tab session sync, OpenAPI codegen.
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