## What & why
S-09b (#75, split from #10) — the **approval flow** that completes the walking skeleton. A behandelaar can now approve a submitted registration; the entry flips from `INGEDIEND` to `INGESCHREVEN` in the public register. Flow: `POST /registrations/{id}/approve` (domain) → ACL sets the zaak eindstatus (ZGW `/statussen`) → OpenZaak → NRC → event-subscriber → projection → openbaar.
## Changes (bottom-up, each red→green TDD)
- **Domain** — `RegistrationStatus.Ingeschreven` + `Registration.Approve()` (guards: opened zaak, only from INGEDIEND); `ApproveRegistration` use case (idempotent) + temp `POST /registrations/{id}/approve` endpoint; `IAclClient.ApproveZaakAsync`.
- **ACL** — resolves the zaaktype's **eindstatus** from the catalogus (`isEindstatus` / highest volgnummer) and POSTs a ZGW status; exposed as `POST /statussen`. Unit + real-OpenZaak integration test.
- **Event-subscriber** — binds NRC `hoofdObject`, projects a `status`/`create` as `INGESCHREVEN` keyed on the zaak (updates the existing row), **without reading OpenZaak** (§8.1). Retains the ZGW `resource` in the log (new column + EF migration) so a rebuild reproduces the status.
- **e2e** — extended: submit → public INGEDIEND → approve → public INGESCHREVEN.
- **Docs** — ADR-0011 (the two non-obvious decisions + the walking-skeleton assumption) + demo note.
## Key decisions (see ADR-0011)
- **ACL discovers the eindstatus** (chosen over injecting a statustype URL): no new config/seed plumbing, domain stays ZGW-ignorant.
- **Any post-creation status-set ⇒ INGESCHREVEN**: in the walking skeleton the only status ever set after creation is the approval, and the subscriber may not read ZGW — documented to tighten when more transitions arrive (S-12+).
## Verification
- All .NET unit suites green locally (domain 47, acl 11, event-subscriber 14, bff 16, acceptance 7); Release build + `dotnet format` clean.
- No new compose config (the eindstatus-discovery approach avoided it).
- The real-OpenZaak integration test (ACL status-set) and the full submit→approve→visible e2e run in CI `verify-stack` (live NRC→projection + selectielijst egress, not reproducible locally).
closes#75
Reviewed-on: #77
S-04a: the deferred S-04 acceptance criterion. A gated Acl.IntegrationTests
project (Category=Integration) drives the real OpenZaakGateway against the
running compose stack — real ZGW JWT auth and the real POST /zaken contract a
stubbed HttpMessageHandler cannot exercise. The lane is kept out of the fast
checks: make unit filters Category!=Integration, Stryker is pinned to Acl.Tests,
and a new make integration target brings the stack up, seeds a published zaaktype
and tears down.
Red: against real OpenZaak the gateway POST fails 400 — JsonContent streams the
body chunked and OpenZaak's uwsgi rejects it. Fixed in the next commit.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
