# WP-08 — One store idiom + machine naming + TEA MDX

Status: done
Phase: 1 — FP/DDD core

## Why

Docs (`docs/fp-tea-atomic-design.md`, ARCHITECTURE §2c) teach `createStore` as THE
wiring, but the wizard pages hand-wire `signal(model)` + local `dispatch()` — juniors see
two idioms and copy the wrong one. Machine naming also drifts:
`change-request.machine.ts` exports bare `State`/`Msg`; `upload.machine.ts` exports
`reduceUpload`/`initialUpload`.

## Read first

- `src/app/shared/application/store.ts` (`createStore`) + its spec
- `docs/fp-tea-atomic-design.md` Part on TEA-in-Angular
- All `*.machine.ts` files (6) and their UI wiring sites (wizard components/pages)

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

- **`createStore` is THE idiom** — migrate the hand-wired pages to it. One shape
  everywhere is the teachability win; the migration is ~5 lines per page.
- Naming convention (goes into CLAUDE.md §3):
  - State/Msg types are context-prefixed: `ChangeRequestState`, `ChangeRequestMsg` (rename
    the bare ones; other machines already comply).
  - A top-level machine exports `initial` + `reduce`.
  - A **composable sub-machine** (embedded in a parent model) keeps prefixed value
    exports: `initialUpload`/`reduceUpload` **stay** — prefixing avoids alias noise at
    the composition site.

## Files

- `src/app/registratie/domain/change-request.machine.ts` (+ spec + consumers) — rename
- Wizard UI wiring: `registratie-wizard.component.ts`, `intake-wizard.component.ts`,
  `herregistratie-wizard.component.ts` (whichever hand-wire `signal`+dispatch) →
  `createStore`
- `CLAUDE.md` §3 — the naming + wiring convention
- New `src/docs/machines.mdx` — title `Foundations/State Machines (TEA)`

## Steps

1. Rename `State`/`Msg` in change-request (mechanical; lint/build finds consumers).
2. Swap hand-wired model signals for `createStore(initial, reduce)` in the wizard
   components; templates keep dispatching messages — no template changes expected.
3. Write the convention into CLAUDE.md §3 (including the sub-machine rule).
4. MDX page: Model/Msg/reduce, commands-outside-reducers, `createStore` wiring, the
   naming rules — linking `herregistratie.machine.ts` as the worked example.

## Acceptance criteria

- [x] `grep -rn "export type State\b\|export type Msg\b" src/app` → empty.
- [x] Every machine consumer wires via `createStore`; no local `signal(model)` +
      hand-rolled dispatch remains.
- [x] Convention documented in CLAUDE.md; MDX renders.
- [x] All machine specs pass unchanged (reducers untouched).

## Verification

GREEN + `npm run test-storybook:ci` (197 unit / 137 Storybook, unchanged from WP-07 —
this WP touched no reducer logic). Manual smoke via a running `docker compose` stack +
Playwright: the change-request form (the renamed machine) submitted end-to-end with a
referentie shown; the intake wizard stepped forward and back; the herregistratie wizard
loaded its first step — no console errors across all three.

## Deviation from the original plan

**Step 2 (migrate wizard pages off hand-wired `signal(model)`+`dispatch()` onto
`createStore`) turned out to already be done.** `registratie-wizard.component.ts`,
`intake-wizard.component.ts`, `herregistratie-wizard.component.ts`, and
`change-request-form.component.ts` all already wire
`createStore<XState, XMsg>(initial, reduce)` — confirmed both by reading each file and by
`git log -p` on `registratie-wizard.component.ts`, which shows `createStore` present
since the file's introduction. `grep -rn "= signal<.*State>\|= signal(init" src/app`
(excluding specs) turns up nothing outside `store.ts` itself and `brief.store.ts`'s two
unrelated transient-state signals (WP-07). The WP's "Why" section was accurate for an
earlier snapshot of the codebase but stale by the time this WP ran — only the
`change-request.machine.ts` naming fix (Step 1) and the CLAUDE.md/MDX documentation
(Steps 3–4) had real work left.

## Out of scope

Changing reducer logic or messages; store specs for root stores (they're covered where
logic exists).

## Risks

Rename ripple — purely mechanical; reducer specs are the net.
