refactor(specs): replay real messages in 4 machine specs (RB-31)

Four machine specs built their starting state with a hand-rolled object
literal instead of replaying real Msgs through the real reduce, the
exact anti-pattern ADR-0006 section 2 forbids. Three of the four also
hardcoded errors: {}, a shape the reducer might never actually produce.

intake.machine.spec.ts now imports the existing givenIntake from
intake.testing.ts (previously used only by intake.acceptance.spec.ts).
Three new one-line *.testing.ts files export the same given(reduce,
initial) wrapper for registratie-wizard, besluit, and brief. Every old
literal helper (answering, invullen, editingWith, loaded) is replaced
by a message replay that reaches the same state.

Two tests in registratie-wizard.machine.spec.ts asserted a cursor value
the real reducer cannot reach (cursor 2 with no diploma chosen yet,
which requires a diploma to already be set). Both are re-pointed at the
reachable cursor-1 equivalent; submit() validates the whole draft
regardless of cursor, so no assertion changed. Recorded in
implementation/rb-31.md, not worked around.

No *.machine.ts reducer was touched. All four specs pass; npm run ci
is green (lint, typecheck, dep:check, format, tokens, seam, all four
test suites, both app builds, backend 293/293, api-client drift).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

apps/behandelportal/src/app/behandeling/domain/besluit.machine.spec.ts

@@ -1,12 +1,7 @@
 import { describe, it, expect } from 'vitest';
 import { expectTag } from '@shared/testing/expect-tag';
-import { BesluitState, reduce, initial } from './besluit.machine';
-
-const editingWith = (besluit: string, toelichting = ''): BesluitState => ({
-  tag: 'Editing',
-  draft: { besluit, toelichting },
-  errors: {},
-});
+import { reduce, initial } from './besluit.machine';
+import { givenBesluit } from './besluit.testing';
 
 describe('besluit reduce', () => {
   it('SetField updates the draft while editing', () => {
@@ -15,17 +10,23 @@ describe('besluit reduce', () => {
   });
 
   it('Submit with no besluit chosen stays Editing and reports a field error', () => {
-    const s = reduce(editingWith(''), { tag: 'Submit' });
+    const s = reduce(initial, { tag: 'Submit' });
     expect(expectTag(s, 'Editing').errors.besluit).toBeTruthy();
   });
 
   it('Submit Afwijzen without a toelichting stays Editing and reports a field error', () => {
-    const s = reduce(editingWith('Afwijzen'), { tag: 'Submit' });
+    const editingAfwijzen = givenBesluit({ tag: 'SetField', key: 'besluit', value: 'Afwijzen' });
+    const s = reduce(editingAfwijzen, { tag: 'Submit' });
     expect(expectTag(s, 'Editing').errors.toelichting).toBeTruthy();
   });
 
   it('Submit Goedkeuren with no toelichting moves to Submitting (optional there)', () => {
-    const s = reduce(editingWith('Goedkeuren'), { tag: 'Submit' });
+    const editingGoedkeuren = givenBesluit({
+      tag: 'SetField',
+      key: 'besluit',
+      value: 'Goedkeuren',
+    });
+    const s = reduce(editingGoedkeuren, { tag: 'Submit' });
     expect(expectTag(s, 'Submitting').data).toEqual({
       besluit: 'Goedkeuren',
       toelichting: undefined,
@@ -33,7 +34,11 @@ describe('besluit reduce', () => {
   });
 
   it('Submit Afwijzen with a toelichting moves to Submitting with the trimmed value', () => {
-    const s = reduce(editingWith('Afwijzen', '  niet erkend  '), { tag: 'Submit' });
+    const editingAfwijzenWithToelichting = givenBesluit(
+      { tag: 'SetField', key: 'besluit', value: 'Afwijzen' },
+      { tag: 'SetField', key: 'toelichting', value: '  niet erkend  ' },
+    );
+    const s = reduce(editingAfwijzenWithToelichting, { tag: 'Submit' });
     expect(expectTag(s, 'Submitting').data).toEqual({
       besluit: 'Afwijzen',
       toelichting: 'niet erkend',
@@ -41,24 +46,36 @@ describe('besluit reduce', () => {
   });
 
   it('SubmitConfirmed maps Submitting to Submitted', () => {
-    const submitting = reduce(editingWith('Goedkeuren'), { tag: 'Submit' });
+    const submitting = givenBesluit(
+      { tag: 'SetField', key: 'besluit', value: 'Goedkeuren' },
+      { tag: 'Submit' },
+    );
     expect(reduce(submitting, { tag: 'SubmitConfirmed' }).tag).toBe('Submitted');
   });
 
   it('SubmitFailed maps Submitting to Failed with the error', () => {
-    const submitting = reduce(editingWith('Goedkeuren'), { tag: 'Submit' });
+    const submitting = givenBesluit(
+      { tag: 'SetField', key: 'besluit', value: 'Goedkeuren' },
+      { tag: 'Submit' },
+    );
     const failed = reduce(submitting, { tag: 'SubmitFailed', error: 'boom' });
     expect(failed).toMatchObject({ tag: 'Failed', error: 'boom' });
   });
 
   it('Retry re-submits a failure', () => {
-    const submitting = reduce(editingWith('Goedkeuren'), { tag: 'Submit' });
+    const submitting = givenBesluit(
+      { tag: 'SetField', key: 'besluit', value: 'Goedkeuren' },
+      { tag: 'Submit' },
+    );
     const failed = reduce(submitting, { tag: 'SubmitFailed', error: 'boom' });
     expect(reduce(failed, { tag: 'Retry' }).tag).toBe('Submitting');
   });
 
   it('Reset returns to the initial editing state', () => {
-    const submitting = reduce(editingWith('Goedkeuren'), { tag: 'Submit' });
+    const submitting = givenBesluit(
+      { tag: 'SetField', key: 'besluit', value: 'Goedkeuren' },
+      { tag: 'Submit' },
+    );
     expect(reduce(submitting, { tag: 'Reset' })).toEqual(initial);
   });
 });

apps/behandelportal/src/app/behandeling/domain/besluit.testing.ts

@@ -0,0 +1,7 @@
+import { given } from '@shared/testing/machine';
+import { reduce, initial } from './besluit.machine';
+
+/** Replay real `BesluitMsg`s through the real `reduce`, starting from `initial`.
+    Pure TS only (no Angular) — domain/ stays framework-free (dependency-cruiser
+    `domain-is-pure`). See `libs/shared/src/testing/machine.ts`. */
+export const givenBesluit = given(reduce, initial);