docs(architecture): ADR-0011 approval status flow + demo note (refs #75)

Records the two non-obvious decisions: the ACL resolves the zaaktype eindstatus
(domain stays ZGW-ignorant), and the event-subscriber projects INGESCHREVEN from
the notification alone (hoofdObject + any status-create), never reading OpenZaak.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/architecture/adr-0011-approval-status-flow.md

@@ -0,0 +1,64 @@
+# ADR-0011: Approval sets the zaak eindstatus via the ACL and projects INGESCHREVEN from the notification alone
+
+- **Status:** Accepted
+- **Date:** 2026-07-13
+- **Deciders:** Respellion engineering
+- **Relates to:** S-09b (#75); split from S-09 (#10); builds on ADR-0001 (§8 loose coupling), ADR-0003 (ACL default-fill), ADR-0007 (OZ→NRC wiring), ADR-0008 (read projection), ADR-0009 (external-task worker)
+
+## Context
+
+The walking skeleton could submit a registration (INGEDIEND) and show it in the openbaar register,
+but nothing could **approve** it. S-09b adds a behandelaar approval that must make the entry publicly
+visible as a terminal status. There is no behandel-portal yet (S-12), so approval is triggered by a
+**temporary admin endpoint** on the Domain Service.
+
+Two decisions are non-obvious (§14) and cross service boundaries:
+
+1. **Who resolves the ZGW statustype?** Approval means "set the zaak to its final status", but the
+   domain must stay ZGW-ignorant (§8.1 — only the ACL talks to ZGW) and does not know statustype URLs.
+2. **How does the projection learn the new status?** The status is set in OpenZaak, which notifies over
+   NRC; the Event Subscriber projects it. But the subscriber **may not read OpenZaak** (§8.1), and an
+   NRC `status`/`create` notification's `resourceUrl` is the *status* resource, not the zaak, and does
+   not carry the statustype.
+
+## Decision
+
+**Approval flows Domain → ACL → OpenZaak → NRC → Event Subscriber → projection, using only the
+notification's own fields on the read side.**
+
+- **Domain.** `Registration.Approve()` advances INGEDIEND → INGESCHREVEN (requires an opened zaak; a
+  repeat is a no-op). The `ApproveRegistration` use case calls the ACL to set the zaak status, then
+  advances the aggregate. A temporary `POST /registrations/{id}/approve` endpoint drives it.
+- **ACL.** A new `POST /statussen` operation takes only the zaak URL. The ACL resolves the zaaktype's
+  **eindstatus** from the catalogus (`isEindstatus`, falling back to the highest `volgnummer`) and
+  POSTs a ZGW status against the zaak. The domain never names statustypen — the ACL owns the ZGW
+  translation (§8.1, ADR-0003).
+- **Event Subscriber.** It binds the NRC `hoofdObject` (always the zaak URL) and keys the projection on
+  it, so a `zaken`/`status`/`create` notification updates the **same** row the zaak-create created,
+  flipping it to INGESCHREVEN. It takes **any** status-create as the approval — in the walking skeleton
+  the only status ever set after creation is the approval — so it never has to read OpenZaak to learn
+  the statustype. The ZGW `resource` is retained in the notification log (new column) so a rebuild
+  reproduces the right status.
+
+## Consequences
+
+- The domain↔ACL boundary stays clean: the domain hands over a zaak URL and says "approve"; ZGW
+  statustype knowledge lives only in the ACL.
+- The projection remains rebuildable without OpenZaak (§8.1, ADR-0008): the log now records the ZGW
+  resource, which is all a rebuild needs to reproject the status.
+- The openbaar register shows real lifecycle: INGEDIEND on submit, INGESCHREVEN on approval.
+- **Walking-skeleton assumption:** "any status-create ⇒ INGESCHREVEN" holds only while approval is the
+  sole post-creation status transition. When more transitions arrive (beoordeling, afwijzing — S-12+),
+  the subscriber must distinguish statustypen. The honest options then are to carry the statustype
+  omschrijving in the notification `kenmerken`, or to have the ACL resolve it and re-notify — recorded
+  here so future-me revisits this rather than assuming it generalises.
+
+## Alternatives considered
+
+- **Inject the approved statustype URL into the ACL as config** (like the zaaktype URL). Rejected:
+  couples ACL config to seed output and adds compose/run-domain-check plumbing; runtime eindstatus
+  discovery keeps the ACL self-contained for one extra ZGW GET per approval.
+- **Have the Event Subscriber GET the status/statustype from OpenZaak** to map precisely. Rejected:
+  violates §8.1 (only the ACL talks to ZGW) and makes the projection depend on OpenZaak being up.
+- **Record the derived status in the notification log** instead of the ZGW resource. Rejected: the log
+  should retain notification *facts*, not projection semantics; the mapping stays in the projector.

docs/demo-script.md

@@ -195,5 +195,35 @@ curl -fsS http://localhost:8140/openbaar/register | jq   # same public-safe view
 # → [ { "id": "<zaak-uuid>", "status": "INGEDIEND" } ]
 ```
 
-> The register shows `INGEDIEND` entries today; the approval transition to a terminal status
-> (e.g. `INGESCHREVEN`) lands with the approval flow (S-09b, #75).
+> The register shows `INGEDIEND` on submit; approval flips it to `INGESCHREVEN` — see S-09b below.
+
+---
+
+## S-09b — Approval flow (public visibility flips to INGESCHREVEN)
+
+**Outcome:** a behandelaar approves a submitted registration via a temporary admin endpoint (no
+behandel-portal yet — S-12). The approval sets the zaak's final status through the ACL, which flows
+back to the projection over NRC, and the openbaar register then shows the entry as `INGESCHREVEN`.
+
+**The path:** `POST /registrations/{id}/approve` (domain) → ACL sets the zaak eindstatus (ZGW
+`/statussen`) → OpenZaak → NRC → Event Subscriber projects `INGESCHREVEN` → openbaar register.
+
+```bash
+# 1. Full stack up, then drive submit → public INGEDIEND → approve → public INGESCHREVEN:
+make up
+make verify-e2e
+
+# 2. Or by hand: submit (as in S-09), note the reference, then approve it.
+#    The zaak is opened off the request path, so approve once GET shows a zaakUrl.
+ref="<registration-reference-from-the-confirmation>"
+curl -fsS http://localhost:8130/registrations/$ref | jq       # domain (host port 8130): wait for .zaakUrl
+curl -fsS -X POST http://localhost:8130/registrations/$ref/approve -i   # → 204 No Content
+
+# 3. The public register now shows the entry as approved.
+curl -fsS http://localhost:8140/openbaar/register | jq
+# → [ { "id": "<zaak-uuid>", "status": "INGESCHREVEN" } ]
+```
+
+> **End of walking skeleton** (S-09 + S-09b): submit → process → projection → public visibility, from
+> INGEDIEND through approval to INGESCHREVEN. The subscriber takes any post-creation status-set as the
+> approval (ADR-0011) — a walking-skeleton assumption that tightens when more transitions arrive (S-12+).

services/acl/Acl.Api/Program.cs

@@ -24,8 +24,18 @@ app.MapPost("/zaken", async (OpenZaakRequest body, AclService acl, CancellationT
     return Results.Ok(new { zaakUrl = zaakUrl.ToString() });
 });
 
+// Approve a zaak: set it to its zaaktype's eindstatus (S-09b). The domain hands over only the zaak
+// URL; the ACL owns the ZGW statustype resolution (§8.1).
+app.MapPost("/statussen", async (SetStatusRequest body, AclService acl, CancellationToken ct) =>
+{
+    await acl.ApproveZaakAsync(new Uri(body.ZaakUrl), ct);
+    return Results.NoContent();
+});
+
 app.Run();
 
 public sealed record OpenZaakRequest(string Bsn);
 
+public sealed record SetStatusRequest(string ZaakUrl);
+
 public partial class Program;

services/acl/Acl.Application/AclService.cs

@@ -17,4 +17,15 @@ public sealed class AclService(IZaakGateway gateway, AclDefaults defaults, ICloc
 
         return gateway.OpenZaakAsync(request, ct);
     }
+
+    /// <summary>
+    /// Approve a zaak: set it to the eindstatus of the configured BIG zaaktype (ADR-0003 default). The
+    /// domain hands over only the zaak URL; the ACL owns which statustype means "approved" (§8.1).
+    /// </summary>
+    public Task ApproveZaakAsync(Uri zaakUrl, CancellationToken ct = default)
+    {
+        ArgumentNullException.ThrowIfNull(zaakUrl);
+
+        return gateway.SetZaakToEindstatusAsync(zaakUrl, defaults.ZaaktypeUrl, clock.Today, ct);
+    }
 }

services/acl/Acl.Application/IZaakGateway.cs

@@ -5,4 +5,11 @@ namespace Acl.Application;
 public interface IZaakGateway
 {
     Task<Uri> OpenZaakAsync(ZaakRequest request, CancellationToken ct = default);
+
+    /// <summary>
+    /// Set the given zaak to the <em>eindstatus</em> (final statustype) of the supplied zaaktype —
+    /// the ZGW translation of "approve". The gateway resolves which statustype is the eindstatus from
+    /// the catalogus and POSTs a status against the zaak, dated <paramref name="datumStatusGezet"/>.
+    /// </summary>
+    Task SetZaakToEindstatusAsync(Uri zaakUrl, Uri zaaktypeUrl, DateOnly datumStatusGezet, CancellationToken ct = default);
 }

services/acl/Acl.Infrastructure/OpenZaakGateway.cs

@@ -41,6 +41,56 @@ public sealed class OpenZaakGateway(HttpClient http, OpenZaakOptions options) :
         return new Uri(created.Url);
     }
 
+    public async Task SetZaakToEindstatusAsync(Uri zaakUrl, Uri zaaktypeUrl, DateOnly datumStatusGezet, CancellationToken ct = default)
+    {
+        ArgumentNullException.ThrowIfNull(zaakUrl);
+        ArgumentNullException.ThrowIfNull(zaaktypeUrl);
+
+        var eindstatus = await ResolveEindstatusAsync(zaaktypeUrl, ct);
+
+        using var message = new HttpRequestMessage(
+            HttpMethod.Post, new Uri(options.BaseUrl, "/zaken/api/v1/statussen"))
+        {
+            Content = JsonContent.Create(new StatusDto(
+                zaakUrl.ToString(),
+                eindstatus.ToString(),
+                // datumStatusGezet is a ZGW date-time; set it at the start of the given day (UTC).
+                datumStatusGezet.ToDateTime(TimeOnly.MinValue, DateTimeKind.Utc).ToString("yyyy-MM-ddTHH:mm:ssZ"))),
+        };
+        message.Headers.Authorization =
+            new AuthenticationHeaderValue("Bearer", ZgwToken.Mint(options.ClientId, options.Secret));
+        // The status resource carries no geometry, so no CRS headers. As with zaak-create, buffer the
+        // body so uwsgi gets a Content-Length instead of a chunked body.
+        await message.Content.LoadIntoBufferAsync(ct);
+
+        using var response = await http.SendAsync(message, ct);
+        response.EnsureSuccessStatusCode();
+    }
+
+    /// <summary>Resolve the zaaktype's eindstatus (the terminal statustype) from the catalogus.</summary>
+    private async Task<Uri> ResolveEindstatusAsync(Uri zaaktypeUrl, CancellationToken ct)
+    {
+        var query = new Uri(options.BaseUrl,
+            "/catalogi/api/v1/statustypen?status=alles&zaaktype=" + Uri.EscapeDataString(zaaktypeUrl.ToString()));
+        using var message = new HttpRequestMessage(HttpMethod.Get, query);
+        message.Headers.Authorization =
+            new AuthenticationHeaderValue("Bearer", ZgwToken.Mint(options.ClientId, options.Secret));
+
+        using var response = await http.SendAsync(message, ct);
+        response.EnsureSuccessStatusCode();
+
+        var page = await response.Content.ReadFromJsonAsync<StatustypePage>(ct)
+            ?? throw new InvalidOperationException("OpenZaak returned an empty statustypen response");
+        var results = page.Results ?? [];
+
+        // OpenZaak flags the terminal statustype (highest volgnummer) as isEindstatus; fall back to the
+        // highest volgnummer if the flag is absent.
+        var eindstatus = results.FirstOrDefault(s => s.IsEindstatus)
+            ?? results.OrderByDescending(s => s.Volgnummer).FirstOrDefault()
+            ?? throw new InvalidOperationException($"No statustypen found for zaaktype {zaaktypeUrl}");
+        return new Uri(eindstatus.Url);
+    }
+
     private sealed record ZaakDto(
         [property: JsonPropertyName("bronorganisatie")] string Bronorganisatie,
         [property: JsonPropertyName("zaaktype")] string Zaaktype,
@@ -50,4 +100,17 @@ public sealed class OpenZaakGateway(HttpClient http, OpenZaakOptions options) :
 
     private sealed record ZaakCreatedDto(
         [property: JsonPropertyName("url")] string Url);
+
+    private sealed record StatusDto(
+        [property: JsonPropertyName("zaak")] string Zaak,
+        [property: JsonPropertyName("statustype")] string Statustype,
+        [property: JsonPropertyName("datumStatusGezet")] string DatumStatusGezet);
+
+    private sealed record StatustypePage(
+        [property: JsonPropertyName("results")] IReadOnlyList<StatustypeDto>? Results);
+
+    private sealed record StatustypeDto(
+        [property: JsonPropertyName("url")] string Url,
+        [property: JsonPropertyName("volgnummer")] int Volgnummer,
+        [property: JsonPropertyName("isEindstatus")] bool IsEindstatus);
 }

services/acl/Acl.IntegrationTests/OpenZaakFixture.cs

@@ -65,6 +65,43 @@ public sealed class OpenZaakFixture : IDisposable
         return JsonDocument.Parse(json).RootElement.Clone();
     }
 
+    /// <summary>GETs a non-geo ZGW resource (e.g. a status) by URL — no CRS headers.</summary>
+    public async Task<JsonElement> GetJsonAsync(Uri url, CancellationToken ct = default)
+    {
+        using var message = new HttpRequestMessage(HttpMethod.Get, url);
+        message.Headers.Authorization = new AuthenticationHeaderValue("Bearer", MintToken());
+
+        using var response = await Http.SendAsync(message, ct);
+        response.EnsureSuccessStatusCode();
+        var json = await response.Content.ReadAsStringAsync(ct);
+        return JsonDocument.Parse(json).RootElement.Clone();
+    }
+
+    /// <summary>The zaaktype's eindstatus (terminal statustype) URL — the one an approval sets.</summary>
+    public async Task<Uri> FindEindstatustypeAsync(Uri zaaktypeUrl, CancellationToken ct = default)
+    {
+        var query = new Uri(BaseUrl,
+            "/catalogi/api/v1/statustypen?status=alles&zaaktype=" + Uri.EscapeDataString(zaaktypeUrl.ToString()));
+        var page = await GetJsonAsync(query, ct);
+        var results = page.GetProperty("results");
+
+        Uri? fallback = null;
+        var highest = int.MinValue;
+        foreach (var st in results.EnumerateArray())
+        {
+            if (st.TryGetProperty("isEindstatus", out var eind) && eind.GetBoolean())
+                return new Uri(st.GetProperty("url").GetString()!);
+            var volgnummer = st.GetProperty("volgnummer").GetInt32();
+            if (volgnummer > highest)
+            {
+                highest = volgnummer;
+                fallback = new Uri(st.GetProperty("url").GetString()!);
+            }
+        }
+
+        return fallback ?? throw new InvalidOperationException($"No statustypen for zaaktype {zaaktypeUrl}");
+    }
+
     // A ZGW (vng-api-common) HS256 JWT, mirroring the seed's client. Minted here
     // rather than reusing Acl.Infrastructure's internal minter to keep that internal.
     private string MintToken()

services/acl/Acl.IntegrationTests/OpenZaakGatewayIntegrationTests.cs

@@ -42,4 +42,32 @@ public sealed class OpenZaakGatewayIntegrationTests(OpenZaakFixture stack)
         Assert.Equal("517439943", zaak.GetProperty("bronorganisatie").GetString());
         Assert.Equal("openbaar", zaak.GetProperty("vertrouwelijkheidaanduiding").GetString());
     }
+
+    [Fact]
+    public async Task Setting_a_zaak_to_its_eindstatus_records_the_terminal_statustype()
+    {
+        var zaaktype = await stack.FindPublishedBigZaaktypeAsync();
+        Assert.True(zaaktype is not null,
+            "No published BIG-REGISTRATIE zaaktype found in OpenZaak — bring the stack up and " +
+            "seed it with OZ_PUBLISH=1 (`make integration` does this).");
+
+        var gateway = new OpenZaakGateway(stack.Http, stack.Options);
+        var zaakUrl = await gateway.OpenZaakAsync(new ZaakRequest(
+            Bronorganisatie: "517439943",
+            VerantwoordelijkeOrganisatie: "517439943",
+            Vertrouwelijkheidaanduiding: "openbaar",
+            Zaaktype: zaaktype!,
+            Startdatum: DateOnly.FromDateTime(DateTime.UtcNow)));
+
+        await gateway.SetZaakToEindstatusAsync(zaakUrl, zaaktype!, DateOnly.FromDateTime(DateTime.UtcNow));
+
+        // The zaak now carries a current status, and it is the zaaktype's eindstatus.
+        var zaak = await stack.GetZaakAsync(zaakUrl);
+        var statusUrl = zaak.GetProperty("status").GetString();
+        Assert.False(string.IsNullOrEmpty(statusUrl), "the approved zaak has no current status");
+
+        var status = await stack.GetJsonAsync(new Uri(statusUrl!));
+        var eindstatustype = await stack.FindEindstatustypeAsync(zaaktype!);
+        Assert.Equal(eindstatustype.ToString(), status.GetProperty("statustype").GetString());
+    }
 }

services/acl/Acl.Tests/AclServiceTests.cs

@@ -9,13 +9,29 @@ public class AclServiceTests
         public ZaakRequest? Captured;
         public Uri Result { get; } = new("http://openzaak/zaken/api/v1/zaken/abc");
 
+        public (Uri Zaak, Uri Zaaktype, DateOnly Datum)? Approved;
+
         public Task<Uri> OpenZaakAsync(ZaakRequest request, CancellationToken ct = default)
         {
             Captured = request;
             return Task.FromResult(Result);
         }
+
+        public Task SetZaakToEindstatusAsync(Uri zaakUrl, Uri zaaktypeUrl, DateOnly datumStatusGezet, CancellationToken ct = default)
+        {
+            Approved = (zaakUrl, zaaktypeUrl, datumStatusGezet);
+            return Task.CompletedTask;
+        }
     }
 
+    private static AclDefaults Defaults() => new()
+    {
+        Bronorganisatie = "517439943",
+        VerantwoordelijkeOrganisatie = "517439943",
+        Vertrouwelijkheidaanduiding = "openbaar",
+        ZaaktypeUrl = new("http://openzaak/catalogi/api/v1/zaaktypen/big"),
+    };
+
     private sealed class FixedClock(DateOnly today) : IClock
     {
         public DateOnly Today { get; } = today;
@@ -61,4 +77,30 @@ public class AclServiceTests
         await Assert.ThrowsAsync<ArgumentNullException>(() => service.OpenZaakAsync(null!));
         Assert.Null(gateway.Captured);
     }
+
+    [Fact]
+    public async Task Approving_a_zaak_sets_it_to_its_zaaktypes_eindstatus_dated_today()
+    {
+        var gateway = new FakeGateway();
+        var defaults = Defaults();
+        var service = new AclService(gateway, defaults, new FixedClock(new DateOnly(2026, 6, 4)));
+        var zaak = new Uri("http://openzaak/zaken/api/v1/zaken/abc");
+
+        await service.ApproveZaakAsync(zaak);
+
+        Assert.NotNull(gateway.Approved);
+        Assert.Equal(zaak, gateway.Approved!.Value.Zaak);
+        Assert.Equal(defaults.ZaaktypeUrl, gateway.Approved.Value.Zaaktype);
+        Assert.Equal(new DateOnly(2026, 6, 4), gateway.Approved.Value.Datum);
+    }
+
+    [Fact]
+    public async Task Approving_a_null_zaak_is_rejected_without_touching_the_gateway()
+    {
+        var gateway = new FakeGateway();
+        var service = new AclService(gateway, Defaults(), new FixedClock(new DateOnly(2026, 6, 4)));
+
+        await Assert.ThrowsAsync<ArgumentNullException>(() => service.ApproveZaakAsync(null!));
+        Assert.Null(gateway.Approved);
+    }
 }

services/domain/Big.Api/Program.cs

@@ -23,6 +23,7 @@ builder.Services.AddTransient<IExternalWorkerClient>(sp => sp.GetRequiredService
 builder.Services.AddHttpClient<IAclClient, AclHttpClient>();
 
 builder.Services.AddScoped<SubmitRegistration>();
+builder.Services.AddScoped<ApproveRegistration>();
 builder.Services.AddScoped<OpenZaakWorker>();
 builder.Services.AddScoped<OpenZaakJobProcessor>();
 
@@ -42,6 +43,18 @@ app.MapPost("/registrations", async (SubmitRegistrationRequest body, SubmitRegis
     return Results.Accepted($"/registrations/{id}", new RegistrationResponse(id.ToString(), RegistrationStatus.Ingediend.ToString(), null));
 });
 
+// Temporary admin endpoint (S-09b): approve a registration — the behandelaar's decision, until the
+// behandel-portal exists (S-12). The zaak's final status is set via the ACL, which flows back over
+// NRC to the projection, making the entry publicly visible as INGESCHREVEN. Idempotent.
+app.MapPost("/registrations/{id}/approve", async (string id, ApproveRegistration approve, CancellationToken ct) =>
+{
+    if (!Guid.TryParse(id, out var guid))
+        return Results.NotFound();
+
+    await approve.HandleAsync(new ApproveRegistrationCommand(new RegistrationId(guid)), ct);
+    return Results.NoContent();
+});
+
 // Read a registration. Its zaak URL appears once the worker has opened the zaak (eventually).
 app.MapGet("/registrations/{id}", async (string id, IRegistrationStore store, CancellationToken ct) =>
 {

services/domain/Big.Application/ApproveRegistration.cs

@@ -0,0 +1,36 @@
+using Big.Domain;
+
+namespace Big.Application;
+
+/// <summary>A behandelaar's decision to approve a registration, in domain language.</summary>
+public sealed record ApproveRegistrationCommand(RegistrationId RegistrationId);
+
+/// <summary>
+/// The approve use case (S-09b): set the registration's zaak to its final status via the ACL (§8.1),
+/// then advance the aggregate to INGESCHREVEN. Idempotent — a redelivered or repeated approval of an
+/// already-approved registration is a no-op, so the ACL is not asked to set the status twice. The
+/// zaak status is the projection's source of truth (it flows back over NRC); the aggregate transition
+/// keeps the domain's own view consistent.
+/// </summary>
+public sealed class ApproveRegistration(IRegistrationStore store, IAclClient acl)
+{
+    public async Task HandleAsync(ApproveRegistrationCommand command, CancellationToken ct = default)
+    {
+        ArgumentNullException.ThrowIfNull(command);
+
+        var registration = await store.GetAsync(command.RegistrationId, ct)
+            ?? throw new InvalidOperationException($"No registration {command.RegistrationId} to approve.");
+
+        // A repeated approval is a no-op: don't set the zaak status a second time.
+        if (registration.Status == RegistrationStatus.Ingeschreven)
+            return;
+
+        if (registration.ZaakUrl is null)
+            throw new InvalidOperationException(
+                $"Registration {command.RegistrationId} has no zaak yet; it cannot be approved.");
+
+        await acl.ApproveZaakAsync(registration.ZaakUrl, ct);
+        registration.Approve();
+        await store.SaveAsync(registration, ct);
+    }
+}

services/domain/Big.Application/Ports.cs

@@ -25,6 +25,12 @@ public interface IWorkflowClient
 public interface IAclClient
 {
     Task<Uri> OpenZaakAsync(string bsn, CancellationToken ct = default);
+
+    /// <summary>
+    /// Record the approval on the given zaak. The ACL translates this to the ZGW concept — setting
+    /// the zaak's final status — which OpenZaak notifies over NRC; the domain never names statustypen.
+    /// </summary>
+    Task ApproveZaakAsync(Uri zaakUrl, CancellationToken ct = default);
 }
 
 /// <summary>

services/domain/Big.Domain/Registration.cs

@@ -64,4 +64,23 @@ public sealed class Registration
 
         ZaakUrl = zaakUrl;
     }
+
+    /// <summary>
+    /// Approve the registration — the behandelaar's decision to enter it in the register. Advances
+    /// <see cref="RegistrationStatus.Ingediend"/> → <see cref="RegistrationStatus.Ingeschreven"/>.
+    /// Requires an opened zaak (the approval sets that zaak's status via the ACL), and only a
+    /// submitted registration can be approved: re-approving is rejected as an invalid transition.
+    /// </summary>
+    public void Approve()
+    {
+        if (ZaakUrl is null)
+            throw new InvalidOperationException(
+                $"Registration {Id} has no zaak yet; it cannot be approved before its zaak is opened.");
+
+        if (Status != RegistrationStatus.Ingediend)
+            throw new InvalidOperationException(
+                $"Registration {Id} is {Status}; only an INGEDIEND registration can be approved.");
+
+        Status = RegistrationStatus.Ingeschreven;
+    }
 }

services/domain/Big.Domain/RegistrationStatus.cs

@@ -1,10 +1,13 @@
 namespace Big.Domain;
 
 /// <summary>The lifecycle states a <see cref="Registration"/> moves through. The walking
-/// skeleton knows only <see cref="Ingediend"/>; withdrawal, beoordeling and herregistratie
-/// states arrive in their own slices (Iteration 2+).</summary>
+/// skeleton knows <see cref="Ingediend"/> and the terminal <see cref="Ingeschreven"/>; withdrawal,
+/// beoordeling and herregistratie states arrive in their own slices (Iteration 2+).</summary>
 public enum RegistrationStatus
 {
     /// <summary>Submitted by the zorgprofessional; the registratie process has been started.</summary>
     Ingediend,
+
+    /// <summary>Approved: entered in the register. Terminal in the walking skeleton (S-09b).</summary>
+    Ingeschreven,
 }

services/domain/Big.Infrastructure/AclHttpClient.cs

@@ -22,7 +22,18 @@ public sealed class AclHttpClient(HttpClient http, AclOptions options) : IAclCli
         return new Uri(opened.ZaakUrl);
     }
 
+    public async Task ApproveZaakAsync(Uri zaakUrl, CancellationToken ct = default)
+    {
+        ArgumentNullException.ThrowIfNull(zaakUrl);
+
+        using var response = await http.PostAsJsonAsync(
+            new Uri(options.BaseUrl, "statussen"), new SetStatusRequest(zaakUrl.ToString()), ct);
+        response.EnsureSuccessStatusCode();
+    }
+
     private sealed record OpenZaakRequest([property: JsonPropertyName("bsn")] string Bsn);
 
     private sealed record OpenZaakResponse([property: JsonPropertyName("zaakUrl")] string ZaakUrl);
+
+    private sealed record SetStatusRequest([property: JsonPropertyName("zaakUrl")] string ZaakUrl);
 }

services/domain/Big.Tests/AclHttpClientTests.cs

@@ -41,4 +41,27 @@ public class AclHttpClientTests
         var ex = await Assert.ThrowsAsync<InvalidOperationException>(() => client.OpenZaakAsync("123456782"));
         Assert.Contains("empty", ex.Message, StringComparison.OrdinalIgnoreCase);
     }
+
+    [Fact]
+    public async Task Approves_a_zaak_by_posting_its_url_to_statussen()
+    {
+        var capture = new RequestCapture();
+        var client = Client(capture.Responds(HttpStatusCode.NoContent));
+
+        await client.ApproveZaakAsync(new Uri("http://openzaak/zaken/api/v1/zaken/abc"));
+
+        Assert.Equal(HttpMethod.Post, capture.Seen!.Method);
+        Assert.Equal("http://acl/statussen", capture.Seen.RequestUri!.ToString());
+        Assert.Contains("\"zaakUrl\":\"http://openzaak/zaken/api/v1/zaken/abc\"", capture.Body);
+    }
+
+    [Fact]
+    public async Task Approve_throws_when_the_acl_rejects_the_request()
+    {
+        var capture = new RequestCapture();
+        var client = Client(capture.Responds(HttpStatusCode.BadGateway));
+
+        await Assert.ThrowsAsync<HttpRequestException>(
+            () => client.ApproveZaakAsync(new Uri("http://openzaak/zaken/api/v1/zaken/abc")));
+    }
 }

services/domain/Big.Tests/ApproveRegistrationTests.cs

@@ -0,0 +1,74 @@
+using Big.Application;
+using Big.Domain;
+
+namespace Big.Tests;
+
+public class ApproveRegistrationTests
+{
+    private static Registration WithZaak(string bsn = "123456782")
+    {
+        var registration = Registration.Submit(bsn);
+        registration.AttachZaak(FakeAclClient.DefaultZaakUrl);
+        return registration;
+    }
+
+    [Fact]
+    public async Task Approving_sets_the_zaak_status_via_the_acl_and_marks_the_registration_ingeschreven()
+    {
+        var store = new FakeRegistrationStore();
+        var acl = new FakeAclClient();
+        var registration = WithZaak();
+        store.Seed(registration);
+        var handler = new ApproveRegistration(store, acl);
+
+        await handler.HandleAsync(new ApproveRegistrationCommand(registration.Id));
+
+        var saved = await store.GetAsync(registration.Id);
+        Assert.Equal(RegistrationStatus.Ingeschreven, saved!.Status);
+        Assert.Equal(FakeAclClient.DefaultZaakUrl, acl.ApprovedZaakUrl);
+        Assert.Equal(1, acl.ApproveCallCount);
+    }
+
+    [Fact]
+    public async Task Approving_an_unknown_registration_throws_and_does_not_call_the_acl()
+    {
+        var store = new FakeRegistrationStore();
+        var acl = new FakeAclClient();
+        var handler = new ApproveRegistration(store, acl);
+
+        await Assert.ThrowsAsync<InvalidOperationException>(
+            () => handler.HandleAsync(new ApproveRegistrationCommand(RegistrationId.New())));
+        Assert.Equal(0, acl.ApproveCallCount);
+    }
+
+    [Fact]
+    public async Task Approving_before_the_zaak_is_opened_throws_without_calling_the_acl()
+    {
+        var store = new FakeRegistrationStore();
+        var acl = new FakeAclClient();
+        var registration = Registration.Submit("123456782"); // no zaak yet
+        store.Seed(registration);
+        var handler = new ApproveRegistration(store, acl);
+
+        await Assert.ThrowsAsync<InvalidOperationException>(
+            () => handler.HandleAsync(new ApproveRegistrationCommand(registration.Id)));
+        Assert.Equal(0, acl.ApproveCallCount);
+    }
+
+    [Fact]
+    public async Task Re_approving_an_already_ingeschreven_registration_is_idempotent()
+    {
+        var store = new FakeRegistrationStore();
+        var acl = new FakeAclClient();
+        var registration = WithZaak();
+        store.Seed(registration);
+        var handler = new ApproveRegistration(store, acl);
+
+        await handler.HandleAsync(new ApproveRegistrationCommand(registration.Id));
+        await handler.HandleAsync(new ApproveRegistrationCommand(registration.Id));
+
+        // The second approval is a no-op: the ACL is not asked to set the status again.
+        Assert.Equal(1, acl.ApproveCallCount);
+        Assert.Equal(RegistrationStatus.Ingeschreven, (await store.GetAsync(registration.Id))!.Status);
+    }
+}

services/domain/Big.Tests/Fakes.cs

@@ -52,10 +52,20 @@ internal sealed class FakeAclClient(Uri? zaakUrl = null) : IAclClient
     public string? OpenedForBsn { get; private set; }
     public int CallCount { get; private set; }
 
+    public Uri? ApprovedZaakUrl { get; private set; }
+    public int ApproveCallCount { get; private set; }
+
     public Task<Uri> OpenZaakAsync(string bsn, CancellationToken ct = default)
     {
         CallCount++;
         OpenedForBsn = bsn;
         return Task.FromResult(_zaakUrl);
     }
+
+    public Task ApproveZaakAsync(Uri zaakUrl, CancellationToken ct = default)
+    {
+        ApproveCallCount++;
+        ApprovedZaakUrl = zaakUrl;
+        return Task.CompletedTask;
+    }
 }

services/domain/Big.Tests/RegistrationTests.cs

@@ -87,4 +87,37 @@ public class RegistrationTests
         Assert.Contains("/zaken/abc", ex.Message);
         Assert.Contains("/zaken/other", ex.Message);
     }
+
+    [Fact]
+    public void Approving_a_registration_with_a_zaak_sets_it_ingeschreven()
+    {
+        var registration = Registration.Submit("123456782");
+        registration.AttachZaak(new Uri("http://openzaak/zaken/api/v1/zaken/abc"));
+
+        registration.Approve();
+
+        Assert.Equal(RegistrationStatus.Ingeschreven, registration.Status);
+    }
+
+    [Fact]
+    public void Approving_before_the_zaak_is_opened_is_rejected()
+    {
+        var registration = Registration.Submit("123456782");
+
+        var ex = Assert.Throws<InvalidOperationException>(() => registration.Approve());
+
+        Assert.Contains("no zaak", ex.Message, StringComparison.OrdinalIgnoreCase);
+        Assert.Equal(RegistrationStatus.Ingediend, registration.Status);
+    }
+
+    [Fact]
+    public void Approving_an_already_ingeschreven_registration_is_rejected()
+    {
+        var registration = Registration.Submit("123456782");
+        registration.AttachZaak(new Uri("http://openzaak/zaken/api/v1/zaken/abc"));
+        registration.Approve();
+
+        Assert.Throws<InvalidOperationException>(() => registration.Approve());
+        Assert.Equal(RegistrationStatus.Ingeschreven, registration.Status);
+    }
 }

services/event-subscriber/EventSubscriber.Api/Program.cs

@@ -54,9 +54,9 @@ await app.RunAsync();
 
 /// <summary>The NRC notification body, as Open Notificaties POSTs it. Only the fields the
 /// projection needs are bound; <c>aanmaakdatum</c>/<c>kenmerken</c> are ignored for the minimal slice.</summary>
-public sealed record NotificationDto(string Kanaal, string Resource, string Actie, Uri ResourceUrl)
+public sealed record NotificationDto(string Kanaal, string Resource, string Actie, Uri ResourceUrl, Uri? HoofdObject = null)
 {
-    public Notification ToNotification() => new(Kanaal, Resource, Actie, ResourceUrl);
+    public Notification ToNotification() => new(Kanaal, Resource, Actie, ResourceUrl, HoofdObject);
 }
 
 public partial class Program

services/event-subscriber/EventSubscriber.Application/Notification.cs

@@ -11,14 +11,23 @@ public sealed record Notification(
     string Kanaal,
     string Resource,
     string Actie,
-    Uri ResourceUrl)
+    Uri ResourceUrl,
+    Uri? HoofdObject = null)
 {
-    /// <summary>The only event the walking-skeleton projection reacts to: a zaak being created.</summary>
+    /// <summary>A zaak being created — projected as INGEDIEND.</summary>
     public bool IsZaakCreated =>
         Kanaal == "zaken" && Resource == "zaak" && Actie == "create";
 
-    /// <summary>The zaak UUID — the trailing path segment of the resource URL — used as the projection key.</summary>
-    public string ZaakId => ResourceUrl.Segments[^1].Trim('/');
+    /// <summary>A status being set on a zaak — the approval, projected as INGESCHREVEN (S-09b). In the
+    /// walking skeleton the only status ever set after creation is the approval, and the subscriber may
+    /// not read OpenZaak (§8.1), so any status-create is taken as the approval.</summary>
+    public bool IsZaakStatusSet =>
+        Kanaal == "zaken" && Resource == "status" && Actie == "create";
+
+    /// <summary>The zaak UUID used as the projection key. For a status notification the resource URL is
+    /// the status, so the zaak comes from <c>hoofdObject</c> (which, for a zaak-create, equals the
+    /// resource URL) — see the NRC payload note.</summary>
+    public string ZaakId => (HoofdObject ?? ResourceUrl).Segments[^1].Trim('/');
 
     /// <summary>
     /// A deterministic dedup key. Open Notificaties carries no notification id and may

services/event-subscriber/EventSubscriber.Application/NotificationProjector.cs

@@ -7,13 +7,15 @@ namespace EventSubscriber.Application;
 /// </summary>
 public sealed class NotificationProjector(INotificationLog log, IProjectionStore store)
 {
-    /// <summary>Handle one inbound notification. Ignores anything that is not a zaak-created event.</summary>
+    /// <summary>Handle one inbound notification. Reacts to a zaak being created (INGEDIEND) and a
+    /// status being set (INGESCHREVEN); ignores everything else.</summary>
     public async Task HandleAsync(Notification notification, CancellationToken ct = default)
     {
-        if (!notification.IsZaakCreated)
+        if (!notification.IsZaakCreated && !notification.IsZaakStatusSet)
             return;
 
-        var recorded = new RecordedNotification(notification.IdempotencyKey, notification.Actie, notification.ZaakId);
+        var recorded = new RecordedNotification(
+            notification.IdempotencyKey, notification.Actie, notification.ZaakId, notification.Resource);
 
         // Atomic record-or-skip: a duplicate (or concurrent) delivery is recognised and dropped
         // before it touches the projection, so the projection stays a faithful derived artefact.
@@ -31,8 +33,10 @@ public sealed class NotificationProjector(INotificationLog log, IProjectionStore
             await store.UpsertAsync(ToEntry(recorded), ct);
     }
 
-    /// <summary>The minimal projection row for an accepted notification. A zaak-create maps to
-    /// INGEDIEND; bsn/naam are deferred (ADR-0008).</summary>
+    /// <summary>The projection row for an accepted notification: a status-set maps to INGESCHREVEN,
+    /// a zaak-create to INGEDIEND. bsn/naam are deferred (ADR-0008).</summary>
     private static RegisterEntry ToEntry(RecordedNotification recorded)
-        => new(recorded.ZaakId, RegistrationStatus.Ingediend);
+        => new(recorded.ZaakId, recorded.Resource == "status"
+            ? RegistrationStatus.Ingeschreven
+            : RegistrationStatus.Ingediend);
 }

services/event-subscriber/EventSubscriber.Application/Ports.cs

@@ -19,8 +19,10 @@ public interface INotificationLog
     Task<IReadOnlyList<RecordedNotification>> AllAsync(CancellationToken ct = default);
 }
 
-/// <summary>A notification that has been accepted, retaining what a rebuild needs to recompute its projection row.</summary>
-public sealed record RecordedNotification(string Key, string Actie, string ZaakId);
+/// <summary>A notification that has been accepted, retaining what a rebuild needs to recompute its
+/// projection row — including the ZGW <c>resource</c>, which distinguishes a zaak-create (INGEDIEND)
+/// from a status-set (INGESCHREVEN) so a rebuild reproduces the right status.</summary>
+public sealed record RecordedNotification(string Key, string Actie, string ZaakId, string Resource);
 
 /// <summary>The read projection store. Owned by the projection bounded context (ADR-0008); the
 /// subscriber writes to it and the projection-api reads it.</summary>

services/event-subscriber/EventSubscriber.Application/RegisterEntry.cs

@@ -17,4 +17,7 @@ public static class RegistrationStatus
 {
     /// <summary>A zaak has been created; the registration is submitted.</summary>
     public const string Ingediend = "INGEDIEND";
+
+    /// <summary>The registration has been approved and entered in the register (S-09b).</summary>
+    public const string Ingeschreven = "INGESCHREVEN";
 }

services/event-subscriber/EventSubscriber.Tests/NotificationProjectorTests.cs

@@ -8,6 +8,7 @@ namespace EventSubscriber.Tests;
 public sealed class NotificationProjectorTests
 {
     private const string ZaakUrl = "http://openzaak:8000/zaken/api/v1/zaken/11111111-1111-1111-1111-111111111111";
+    private const string StatusUrl = "http://openzaak:8000/zaken/api/v1/statussen/22222222-2222-2222-2222-222222222222";
 
     private readonly InMemoryNotificationLog _log = new();
     private readonly InMemoryProjectionStore _store = new();
@@ -17,6 +18,10 @@ public sealed class NotificationProjectorTests
     private static Notification ZaakCreated(string url = ZaakUrl)
         => new("zaken", "zaak", "create", new Uri(url));
 
+    // A status-set notification: resourceUrl is the status resource, hoofdObject is the zaak it belongs to.
+    private static Notification StatusSet(string zaakUrl = ZaakUrl, string statusUrl = StatusUrl)
+        => new("zaken", "status", "create", new Uri(statusUrl), new Uri(zaakUrl));
+
     [Fact]
     public async Task creating_a_zaak_writes_one_row_with_status_ingediend()
     {
@@ -62,16 +67,53 @@ public sealed class NotificationProjectorTests
     [Theory]
     [InlineData("documenten", "enkelvoudiginformatieobject", "create")] // wrong kanaal + resource
     [InlineData("documenten", "zaak", "create")]                        // wrong kanaal only
-    [InlineData("zaken", "status", "create")]                           // wrong resource only
     [InlineData("zaken", "zaak", "update")]                             // wrong actie
     [InlineData("zaken", "zaak", "destroy")]                            // wrong actie
-    public async Task only_a_zaken_zaak_create_notification_is_projected(string kanaal, string resource, string actie)
+    [InlineData("zaken", "status", "update")]                           // a status change we ignore
+    [InlineData("zaken", "resultaat", "create")]                        // not a status we project
+    public async Task an_unrelated_notification_is_not_projected(string kanaal, string resource, string actie)
     {
         await Projector().HandleAsync(new Notification(kanaal, resource, actie, new Uri(ZaakUrl)));
 
         Assert.Empty(await _store.AllAsync());
     }
 
+    [Fact]
+    public async Task setting_a_status_projects_ingeschreven_keyed_on_the_zaak_not_the_status()
+    {
+        await Projector().HandleAsync(StatusSet());
+
+        var entry = Assert.Single(await _store.AllAsync());
+        // Keyed on the zaak (hoofdObject), not the status resource URL.
+        Assert.Equal("11111111-1111-1111-1111-111111111111", entry.Id);
+        Assert.Equal(RegistrationStatus.Ingeschreven, entry.Status);
+    }
+
+    [Fact]
+    public async Task approving_updates_the_existing_zaak_row_from_ingediend_to_ingeschreven()
+    {
+        var projector = Projector();
+        await projector.HandleAsync(ZaakCreated());
+        await projector.HandleAsync(StatusSet());
+
+        var entry = Assert.Single(await _store.AllAsync());
+        Assert.Equal("11111111-1111-1111-1111-111111111111", entry.Id);
+        Assert.Equal(RegistrationStatus.Ingeschreven, entry.Status);
+    }
+
+    [Fact]
+    public async Task rebuild_reproduces_the_approved_status()
+    {
+        var projector = Projector();
+        await projector.HandleAsync(ZaakCreated());
+        await projector.HandleAsync(StatusSet());
+
+        await projector.RebuildAsync();
+
+        var entry = Assert.Single(await _store.AllAsync());
+        Assert.Equal(RegistrationStatus.Ingeschreven, entry.Status);
+    }
+
     [Fact]
     public async Task rebuild_clears_stale_rows_and_repopulates_from_the_notification_log()
     {

services/projection-api/Projection.ReadModel/EfNotificationLog.cs

@@ -15,6 +15,7 @@ public sealed class EfNotificationLog(ProjectionDbContext db) : INotificationLog
             Key = notification.Key,
             Actie = notification.Actie,
             ZaakId = notification.ZaakId,
+            Resource = notification.Resource,
             ReceivedAt = DateTimeOffset.UtcNow,
         });
 
@@ -34,6 +35,6 @@ public sealed class EfNotificationLog(ProjectionDbContext db) : INotificationLog
     public async Task<IReadOnlyList<RecordedNotification>> AllAsync(CancellationToken ct = default)
         => await db.ProcessedNotifications
             .OrderBy(r => r.ReceivedAt)
-            .Select(r => new RecordedNotification(r.Key, r.Actie, r.ZaakId))
+            .Select(r => new RecordedNotification(r.Key, r.Actie, r.ZaakId, r.Resource))
             .ToListAsync(ct);
 }

services/projection-api/Projection.ReadModel/Migrations/20260713145944_AddNotificationResource.Designer.cs

@@ -0,0 +1,84 @@
+// <auto-generated />
+using System;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+using Projection.ReadModel;
+
+#nullable disable
+
+namespace Projection.ReadModel.Migrations
+{
+    [DbContext(typeof(ProjectionDbContext))]
+    [Migration("20260713145944_AddNotificationResource")]
+    partial class AddNotificationResource
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasAnnotation("ProductVersion", "10.0.0")
+                .HasAnnotation("Relational:MaxIdentifierLength", 63);
+
+            NpgsqlModelBuilderExtensions.UseIdentityByDefaultColumns(modelBuilder);
+
+            modelBuilder.Entity("Projection.ReadModel.ProcessedNotificationRow", b =>
+                {
+                    b.Property<string>("Key")
+                        .HasColumnType("text")
+                        .HasColumnName("key");
+
+                    b.Property<string>("Actie")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("actie");
+
+                    b.Property<DateTimeOffset>("ReceivedAt")
+                        .HasColumnType("timestamp with time zone")
+                        .HasColumnName("received_at");
+
+                    b.Property<string>("Resource")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("resource");
+
+                    b.Property<string>("ZaakId")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("zaak_id");
+
+                    b.HasKey("Key");
+
+                    b.ToTable("processed_notifications", (string)null);
+                });
+
+            modelBuilder.Entity("Projection.ReadModel.RegisterEntryRow", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("text")
+                        .HasColumnName("id");
+
+                    b.Property<string>("Bsn")
+                        .HasColumnType("text")
+                        .HasColumnName("bsn");
+
+                    b.Property<string>("NaamPlaceholder")
+                        .HasColumnType("text")
+                        .HasColumnName("naam_placeholder");
+
+                    b.Property<string>("Status")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("status");
+
+                    b.HasKey("Id");
+
+                    b.ToTable("register_projection", (string)null);
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

services/projection-api/Projection.ReadModel/Migrations/20260713145944_AddNotificationResource.cs

@@ -0,0 +1,31 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Projection.ReadModel.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddNotificationResource : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            // Pre-existing rows are all zaak-creates (the only notification the projector recorded
+            // before S-09b), so default the backfill to "zaak" rather than "".
+            migrationBuilder.AddColumn<string>(
+                name: "resource",
+                table: "processed_notifications",
+                type: "text",
+                nullable: false,
+                defaultValue: "zaak");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "resource",
+                table: "processed_notifications");
+        }
+    }
+}

services/projection-api/Projection.ReadModel/Migrations/ProjectionDbContextModelSnapshot.cs

@@ -37,6 +37,11 @@ namespace Projection.ReadModel.Migrations
                         .HasColumnType("timestamp with time zone")
                         .HasColumnName("received_at");
 
+                    b.Property<string>("Resource")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("resource");
+
                     b.Property<string>("ZaakId")
                         .IsRequired()
                         .HasColumnType("text")

services/projection-api/Projection.ReadModel/ProjectionDbContext.cs

@@ -35,6 +35,7 @@ public sealed class ProjectionDbContext(DbContextOptions<ProjectionDbContext> op
             e.Property(r => r.Key).HasColumnName("key");
             e.Property(r => r.Actie).HasColumnName("actie").IsRequired();
             e.Property(r => r.ZaakId).HasColumnName("zaak_id").IsRequired();
+            e.Property(r => r.Resource).HasColumnName("resource").IsRequired();
             e.Property(r => r.ReceivedAt).HasColumnName("received_at");
         });
     }
@@ -55,5 +56,10 @@ public sealed class ProcessedNotificationRow
     public required string Key { get; set; }
     public required string Actie { get; set; }
     public required string ZaakId { get; set; }
+
+    /// <summary>The ZGW resource (e.g. <c>zaak</c> or <c>status</c>) — retained so a rebuild reprojects
+    /// the right status without reading OpenZaak (S-09b).</summary>
+    public required string Resource { get; set; }
+
     public DateTimeOffset ReceivedAt { get; set; }
 }

tests/acceptance/Support/InMemoryDomainPorts.cs

@@ -26,12 +26,19 @@ public sealed class InMemoryAclClient : IAclClient
     public static readonly Uri OpenedZaakUrl = new("http://openzaak/zaken/api/v1/zaken/acc-zaak");
 
     public string? OpenedForBsn { get; private set; }
+    public Uri? ApprovedZaakUrl { get; private set; }
 
     public Task<Uri> OpenZaakAsync(string bsn, CancellationToken ct = default)
     {
         OpenedForBsn = bsn;
         return Task.FromResult(OpenedZaakUrl);
     }
+
+    public Task ApproveZaakAsync(Uri zaakUrl, CancellationToken ct = default)
+    {
+        ApprovedZaakUrl = zaakUrl;
+        return Task.CompletedTask;
+    }
 }
 
 /// <summary>An in-memory registration store for the domain acceptance scenario.</summary>

tests/acceptance/Support/InMemoryZaakGateway.cs

@@ -11,10 +11,17 @@ public sealed class InMemoryZaakGateway : IZaakGateway
     public static readonly Uri CreatedZaakUrl = new("http://openzaak/zaken/api/v1/zaken/created-123");
 
     public ZaakRequest? Captured { get; private set; }
+    public (Uri Zaak, Uri Zaaktype, DateOnly Datum)? Approved { get; private set; }
 
     public Task<Uri> OpenZaakAsync(ZaakRequest request, CancellationToken ct = default)
     {
         Captured = request;
         return Task.FromResult(CreatedZaakUrl);
     }
+
+    public Task SetZaakToEindstatusAsync(Uri zaakUrl, Uri zaaktypeUrl, DateOnly datumStatusGezet, CancellationToken ct = default)
+    {
+        Approved = (zaakUrl, zaaktypeUrl, datumStatusGezet);
+        return Task.CompletedTask;
+    }
 }

tests/e2e/registration.spec.ts

@@ -1,9 +1,10 @@
 import { expect, test } from '@playwright/test';
 
-// Walking-skeleton happy path (S-08d + S-09): a zorgprofessional logs in via mock DigiD and submits a
-// registration through the self-service portal → BFF → domain; the projection is updated via NRC → the
-// event-subscriber, and the entry becomes publicly visible in the openbaar register portal.
-test('DigiD login → submit → confirmation → public visibility', async ({ page }) => {
+// Walking-skeleton happy path (S-08d + S-09 + S-09b): a zorgprofessional logs in via mock DigiD and
+// submits through the self-service portal → BFF → domain; the entry appears in the openbaar register
+// as INGEDIEND; a behandelaar approves it via the temporary admin endpoint; the approval flows via the
+// ACL → NRC → event-subscriber → projection, and the openbaar register then shows it as INGESCHREVEN.
+test('DigiD login → submit → public INGEDIEND → approve → public INGESCHREVEN', async ({ page, request }) => {
   // Visiting the guarded page redirects to the Keycloak (mock DigiD) login.
   await page.goto('/');
 
@@ -17,8 +18,11 @@ test('DigiD login → submit → confirmation → public visibility', async ({ p
 
   await page.getByRole('button', { name: /indienen/i }).click();
 
-  // The BFF accepted it and the page shows the confirmation.
-  await expect(page.getByText(/ontvangen/i)).toBeVisible();
+  // The BFF accepted it and the page shows the confirmation with the reference.
+  const confirmation = page.getByText(/ontvangen/i);
+  await expect(confirmation).toBeVisible();
+  const reference = (await confirmation.textContent())?.match(/Referentie:\s*([0-9a-fA-F-]+)/)?.[1];
+  expect(reference, 'the confirmation shows a registration reference').toBeTruthy();
 
   // The openbaar register (anonymous, its own origin) shows the submitted entry once the projection
   // catches up. The projection updates asynchronously (NRC → event-subscriber), and the register loads
@@ -31,4 +35,25 @@ test('DigiD login → submit → confirmation → public visibility', async ({ p
       return page.getByRole('cell', { name: 'INGEDIEND' }).count();
     }, { timeout: 30_000, intervals: [1_000, 2_000, 3_000, 5_000] })
     .toBeGreaterThan(0);
+
+  // Approve via the temporary admin endpoint (reached directly on the compose network, as a
+  // behandelaar would until the behandel-portal exists — S-12). The zaak is opened off the request
+  // path by the worker, so wait for it before approving.
+  await expect
+    .poll(async () => {
+      const res = await request.get(`http://domain:8080/registrations/${reference}`);
+      return res.ok() ? (await res.json()).zaakUrl : null;
+    }, { timeout: 30_000, intervals: [1_000, 2_000, 3_000, 5_000] })
+    .toBeTruthy();
+
+  const approve = await request.post(`http://domain:8080/registrations/${reference}/approve`);
+  expect(approve.status()).toBe(204);
+
+  // The approval flows back to the projection; the openbaar register now shows it as INGESCHREVEN.
+  await expect
+    .poll(async () => {
+      await page.reload();
+      return page.getByRole('cell', { name: 'INGESCHREVEN' }).count();
+    }, { timeout: 30_000, intervals: [1_000, 2_000, 3_000, 5_000] })
+    .toBeGreaterThan(0);
 });