# WP-09 — Pure-logic closure: dates + missing command specs

Status: todo
Phase: 1 — FP/DDD core

## Why

Three hand-rolled copies of the same `nl-NL {day: numeric, month: long, year: numeric}`
formatter exist with divergent signatures, while other components use the Angular `date`
pipe — two mechanisms plus drift risk. And two application commands with real logic have
no spec despite "domain and pure logic must have a spec" (CLAUDE.md §5).

## Read first

- `src/app/registratie/domain/tasks.ts` (~line 15, `formatNL(d: Date)`)
- `src/app/registratie/ui/aanvraag-block/aanvraag-block.component.ts` (~line 96,
  `formatNL(iso?: string)`)
- `src/app/brief/ui/letter-preview/letter-preview.component.ts` (~line 96, inline copy)
- `src/app/registratie/application/draft-sync.ts` (debounce logic)
- `src/app/registratie/application/submit-change-request.ts`
- `src/app/app.config.ts` (LOCALE_ID `nl` is already set)

## Decisions (pre-made, don't relitigate)

- **Templates use `DatePipe`; pure TS uses one `formatDatumNl`** in
  `src/app/shared/kernel/datum.ts` (Intl.DateTimeFormat, accepts ISO string | Date,
  empty-safe). Rule goes into CLAUDE.md conventions.
- Kernel naming is Dutch (`datum.ts`) — it formats for the Dutch UI; if that clashes with
  the "shared = English" rule during implementation, `format-date-nl.ts` is the
  alternative — pick one and note it here.

## Files

- New `src/app/shared/kernel/datum.ts` + `datum.spec.ts`
- The three formatter copies (delete, redirect to pipe or kernel fn)
- New `src/app/registratie/application/draft-sync.spec.ts`
- New `src/app/registratie/application/submit-change-request.spec.ts`
- `CLAUDE.md` conventions (one line: DatePipe in templates, `formatDatumNl` in pure TS)

## Steps

1. Write `formatDatumNl` + spec (pin exact expected strings, e.g. `2 juli 2026`;
   undefined/empty → `''`).
2. Replace the three copies; templates that can use the pipe use the pipe.
3. `draft-sync.spec.ts` with vitest fake timers: coalescing (n rapid changes → 1 sync),
   trailing call, flush-on-submit if applicable.
4. `submit-change-request.spec.ts`: ok path, error path (stubbed client), Result shape.
5. Also sweep the tiny dead exports flagged in the audit: remove unused `map3` from
   `shared/kernel/fp.ts` (verify unused first) and the never-set `variant` input on
   `confirmation.component.ts`.

## Acceptance criteria

- [ ] Exactly one hand-written date formatter in the repo; `grep -rn "toLocaleDateString" src/app`
      hits only `datum.ts`.
- [ ] Both command specs exist; debounce coalescing + error path covered.
- [ ] `map3` / unused `variant` input removed (or a note here why kept).
- [ ] CLAUDE.md rule added.

## Verification

GREEN + `npm run test-storybook:ci`.

## Out of scope

`Result` combinators (map/andThen/fold) — nice-to-have from the old roadmap, not in this
backlog.

## Risks

Node ICU vs browser locale output differences — the spec pins strings; if CI's Node lacks
full ICU (it shouldn't on Node 24), pin via `Intl.DateTimeFormat('nl-NL', …)` explicitly.
