diff --git a/libs/api-client/src/lib/generated/bff-api.ts b/libs/api-client/src/lib/generated/bff-api.ts
index ca0d967..ca1d1c3 100644
--- a/libs/api-client/src/lib/generated/bff-api.ts
+++ b/libs/api-client/src/lib/generated/bff-api.ts
@@ -24,6 +24,10 @@ import {
   Observable
 } from 'rxjs';
 
+export interface DecideRequest {
+  besluit: string;
+}
+
 export interface OpenbaarEntry {
   id: string;
   status: string;
@@ -252,4 +256,42 @@ export class BffApiV1Service {
     );
   }
 
+ postBehandelRegistrationsIdDecide<TData = void>(id: string,
+    decideRequest: DecideRequest, options?: HttpClientBodyOptions): Observable<TData>;
+ postBehandelRegistrationsIdDecide<TData = void>(id: string,
+    decideRequest: DecideRequest, options?: HttpClientEventOptions): Observable<HttpEvent<TData>>;
+ postBehandelRegistrationsIdDecide<TData = void>(id: string,
+    decideRequest: DecideRequest, options?: HttpClientResponseOptions): Observable<AngularHttpResponse<TData>>;
+  postBehandelRegistrationsIdDecide<TData = void>(
+    id: string,
+    decideRequest: DecideRequest, options?: HttpClientObserveOptions): Observable<TData | HttpEvent<TData> | AngularHttpResponse<TData>> {
+    if (options?.observe === 'events') {
+      return this.http.post<TData>(
+      `/behandel/registrations/${id}/decide`,
+      decideRequest,{
+        ...(options as Omit<NonNullable<typeof options>, 'observe'>),
+        observe: 'events',
+      }
+    );
+    }
+
+    if (options?.observe === 'response') {
+      return this.http.post<TData>(
+      `/behandel/registrations/${id}/decide`,
+      decideRequest,{
+        ...(options as Omit<NonNullable<typeof options>, 'observe'>),
+        observe: 'response',
+      }
+    );
+    }
+
+    return this.http.post<TData>(
+      `/behandel/registrations/${id}/decide`,
+      decideRequest,{
+        ...(options as Omit<NonNullable<typeof options>, 'observe'>),
+        observe: 'body',
+      }
+    );
+  }
+
 };
diff --git a/services/bff/Bff.Api/DownstreamClients.cs b/services/bff/Bff.Api/DownstreamClients.cs
index 8571641..5c21c85 100644
--- a/services/bff/Bff.Api/DownstreamClients.cs
+++ b/services/bff/Bff.Api/DownstreamClients.cs
@@ -24,6 +24,9 @@ public interface IDomainClient
 
     /// <summary>The behandelaar's werkbak — registrations awaiting beoordeling.</summary>
     Task<IReadOnlyList<WerkbakItem>> GetWerkbakAsync(CancellationToken ct = default);
+
+    /// <summary>Apply a behandelaar's decision (<c>goedkeuren</c>/<c>afwijzen</c>) to a registration.</summary>
+    Task DecideAsync(string registrationId, string besluit, CancellationToken ct = default);
 }
 
 /// <summary>Port to the read projection.</summary>
@@ -47,6 +50,13 @@ public sealed class DomainClient(HttpClient http) : IDomainClient
     public async Task<IReadOnlyList<WerkbakItem>> GetWerkbakAsync(CancellationToken ct = default)
         => await http.GetFromJsonAsync<List<WerkbakItem>>("behandel/werkbak", ct) ?? [];
 
+    public async Task DecideAsync(string registrationId, string besluit, CancellationToken ct = default)
+    {
+        using var response = await http.PostAsJsonAsync(
+            $"registrations/{registrationId}/decide", new { besluit }, ct);
+        response.EnsureSuccessStatusCode();
+    }
+
     private sealed record DomainResponse(string RegistrationId, string Status, string? ZaakUrl);
 }
 
diff --git a/services/bff/Bff.Api/Program.cs b/services/bff/Bff.Api/Program.cs
index 871ae31..1f95d04 100644
--- a/services/bff/Bff.Api/Program.cs
+++ b/services/bff/Bff.Api/Program.cs
@@ -103,8 +103,28 @@ app.MapGet("/behandel/werkbak", async (IDomainClient domain, CancellationToken c
     .Produces(StatusCodes.Status401Unauthorized)
     .Produces(StatusCodes.Status403Forbidden);
 
+// A behandelaar's beoordeling on a registration (goedkeuren/afwijzen). Forwarded to the domain, which
+// applies the decision and completes the workflow task (ADR-0013). Same medewerker/behandelaar gate.
+app.MapPost("/behandel/registrations/{id}/decide",
+    async (string id, DecideRequest body, IDomainClient domain, CancellationToken ct) =>
+    {
+        if (!BehandelAuth.IsKnownBesluit(body.Besluit))
+            return Results.BadRequest(new { error = $"Unknown besluit '{body.Besluit}'. Expected 'goedkeuren' or 'afwijzen'." });
+
+        await domain.DecideAsync(id, body.Besluit, ct);
+        return Results.NoContent();
+    })
+    .RequireAuthorization(BehandelAuth.Policy)
+    .Produces(StatusCodes.Status204NoContent)
+    .Produces(StatusCodes.Status400BadRequest)
+    .Produces(StatusCodes.Status401Unauthorized)
+    .Produces(StatusCodes.Status403Forbidden);
+
 app.Run();
 
+/// <summary>The behandelaar's decision on a registration.</summary>
+public sealed record DecideRequest(string Besluit);
+
 // Behandel (medewerker-realm) authentication + authorization wiring (ADR-0013).
 internal static class BehandelAuth
 {
@@ -112,6 +132,12 @@ internal static class BehandelAuth
     public const string Policy = "behandelaar";
     public const string BehandelaarRole = "behandelaar";
 
+    /// <summary>The beoordeling vocabulary the BFF accepts (case-insensitive); an unknown besluit is a
+    /// 400 without troubling the domain. Mirrors the domain's <c>BeoordelingsBesluit</c>.</summary>
+    public static bool IsKnownBesluit(string? besluit) =>
+        string.Equals(besluit, "goedkeuren", StringComparison.OrdinalIgnoreCase) ||
+        string.Equals(besluit, "afwijzen", StringComparison.OrdinalIgnoreCase);
+
     /// <summary>Lift Keycloak's realm roles (the nested <c>realm_access.roles</c> claim) onto the
     /// principal as role claims, so <c>RequireRole</c> can authorize on them.</summary>
     public static void AddRealmRoles(ClaimsPrincipal? principal)
diff --git a/services/bff/Bff.Tests/BehandelEndpointTests.cs b/services/bff/Bff.Tests/BehandelEndpointTests.cs
index 3d39147..c3e3dfb 100644
--- a/services/bff/Bff.Tests/BehandelEndpointTests.cs
+++ b/services/bff/Bff.Tests/BehandelEndpointTests.cs
@@ -54,4 +54,61 @@ public class BehandelEndpointTests
         Assert.Equal("reg-1", item.RegistrationId);
         Assert.Equal("123456782", item.Bsn);
     }
+
+    private static HttpRequestMessage Decide(string? bearer, string id = "reg-1", string besluit = "goedkeuren")
+    {
+        var request = new HttpRequestMessage(HttpMethod.Post, $"/behandel/registrations/{id}/decide")
+        {
+            Content = JsonContent.Create(new { besluit }),
+        };
+        if (bearer is not null)
+            request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", bearer);
+        return request;
+    }
+
+    [Fact]
+    public async Task Rejects_a_decision_without_a_token()
+    {
+        using var factory = new BffFactory();
+
+        var response = await factory.CreateClient().SendAsync(Decide(bearer: null));
+
+        Assert.Equal(HttpStatusCode.Unauthorized, response.StatusCode);
+        Assert.Null(factory.Domain.Decided);
+    }
+
+    [Fact]
+    public async Task Rejects_a_decision_from_a_medewerker_without_the_behandelaar_role()
+    {
+        using var factory = new BffFactory();
+
+        var response = await factory.CreateClient().SendAsync(Decide(TestTokens.Medewerker("teamlead")));
+
+        Assert.Equal(HttpStatusCode.Forbidden, response.StatusCode);
+        Assert.Null(factory.Domain.Decided);
+    }
+
+    [Fact]
+    public async Task Forwards_a_behandelaar_decision_to_the_domain()
+    {
+        using var factory = new BffFactory();
+
+        var response = await factory.CreateClient()
+            .SendAsync(Decide(TestTokens.Medewerker("behandelaar"), id: "reg-42", besluit: "afwijzen"));
+
+        Assert.Equal(HttpStatusCode.NoContent, response.StatusCode);
+        Assert.Equal(("reg-42", "afwijzen"), factory.Domain.Decided);
+    }
+
+    [Fact]
+    public async Task Rejects_an_unknown_besluit_without_calling_the_domain()
+    {
+        using var factory = new BffFactory();
+
+        var response = await factory.CreateClient()
+            .SendAsync(Decide(TestTokens.Medewerker("behandelaar"), besluit: "misschien"));
+
+        Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
+        Assert.Null(factory.Domain.Decided);
+    }
 }
diff --git a/services/bff/Bff.Tests/BffFactory.cs b/services/bff/Bff.Tests/BffFactory.cs
index 5e74fb9..3cf1e67 100644
--- a/services/bff/Bff.Tests/BffFactory.cs
+++ b/services/bff/Bff.Tests/BffFactory.cs
@@ -82,8 +82,16 @@ internal sealed class FakeDomainClient : IDomainClient
         return Task.FromResult(Result);
     }
 
+    public (string RegistrationId, string Besluit)? Decided { get; private set; }
+
     public Task<IReadOnlyList<WerkbakItem>> GetWerkbakAsync(CancellationToken ct = default)
         => Task.FromResult<IReadOnlyList<WerkbakItem>>(Werkbak);
+
+    public Task DecideAsync(string registrationId, string besluit, CancellationToken ct = default)
+    {
+        Decided = (registrationId, besluit);
+        return Task.CompletedTask;
+    }
 }
 
 /// <summary>Serves a configurable set of projection rows.</summary>
diff --git a/services/bff/openapi.json b/services/bff/openapi.json
index e3591c3..272d9e3 100644
--- a/services/bff/openapi.json
+++ b/services/bff/openapi.json
@@ -88,10 +88,62 @@
           }
         }
       }
+    },
+    "/behandel/registrations/{id}/decide": {
+      "post": {
+        "tags": [
+          "Bff.Api"
+        ],
+        "parameters": [
+          {
+            "name": "id",
+            "in": "path",
+            "required": true,
+            "schema": {
+              "type": "string"
+            }
+          }
+        ],
+        "requestBody": {
+          "content": {
+            "application/json": {
+              "schema": {
+                "$ref": "#/components/schemas/DecideRequest"
+              }
+            }
+          },
+          "required": true
+        },
+        "responses": {
+          "204": {
+            "description": "No Content"
+          },
+          "400": {
+            "description": "Bad Request"
+          },
+          "401": {
+            "description": "Unauthorized"
+          },
+          "403": {
+            "description": "Forbidden"
+          }
+        }
+      }
     }
   },
   "components": {
     "schemas": {
+      "DecideRequest": {
+        "required": [
+          "besluit"
+        ],
+        "type": "object",
+        "properties": {
+          "besluit": {
+            "type": "string"
+          }
+        }
+      },
       "OpenbaarEntry": {
         "required": [
           "id",
diff --git a/services/domain/Big.Application/BeoordeelRegistratie.cs b/services/domain/Big.Application/BeoordeelRegistratie.cs
index f0a384f..8ba8e3f 100644
--- a/services/domain/Big.Application/BeoordeelRegistratie.cs
+++ b/services/domain/Big.Application/BeoordeelRegistratie.cs
@@ -20,10 +20,12 @@ public sealed record BeoordeelRegistratieCommand(RegistrationId RegistrationId,
 /// <see cref="BeoordelingsBesluit.Goedkeuren"/> sets the zaak's final status via the ACL (§8.1) and
 /// advances the aggregate to INGESCHREVEN; <see cref="BeoordelingsBesluit.Afwijzen"/> advances it to
 /// AFGEWEZEN in the domain (propagating a rejection to the zaak, so the openbaar projection reflects
-/// it, is a later sub-slice of S-12). Both decisions are idempotent — a repeated or redelivered
-/// decision that matches the current terminal state is a no-op, so the ACL is not called twice.
+/// it, is a later sub-slice of S-12). After applying the decision it completes the Flowable
+/// <c>Beoordelen</c> task (found by registrationId) so the workflow advances (ADR-0013). Both
+/// decisions are idempotent — a repeated or redelivered decision that matches the current terminal
+/// state is a no-op, so the ACL is not called and the task not completed twice.
 /// </summary>
-public sealed class BeoordeelRegistratie(IRegistrationStore store, IAclClient acl)
+public sealed class BeoordeelRegistratie(IRegistrationStore store, IAclClient acl, IUserTaskClient tasks)
 {
     public async Task HandleAsync(BeoordeelRegistratieCommand command, CancellationToken ct = default)
     {
@@ -53,5 +55,17 @@ public sealed class BeoordeelRegistratie(IRegistrationStore store, IAclClient ac
         }
 
         await store.SaveAsync(registration, ct);
+        await CompleteWorkflowTaskAsync(command.RegistrationId, command.Besluit, ct);
+    }
+
+    // Advance the workflow: complete the open Beoordelen task for this registration. If none is open
+    // (already completed, or the process hasn't parked yet) the decision still stands — we complete
+    // nothing rather than fail.
+    private async Task CompleteWorkflowTaskAsync(RegistrationId registrationId, BeoordelingsBesluit besluit, CancellationToken ct)
+    {
+        var open = await tasks.GetOpenBeoordelingenAsync(ct);
+        var task = open.FirstOrDefault(t => t.RegistrationId == registrationId);
+        if (task is not null)
+            await tasks.CompleteBeoordelingAsync(task.TaskId, besluit, ct);
     }
 }
diff --git a/services/domain/Big.Tests/BeoordeelRegistratieTests.cs b/services/domain/Big.Tests/BeoordeelRegistratieTests.cs
index de51af2..9ad48de 100644
--- a/services/domain/Big.Tests/BeoordeelRegistratieTests.cs
+++ b/services/domain/Big.Tests/BeoordeelRegistratieTests.cs
@@ -6,8 +6,8 @@ namespace Big.Tests;
 /// <summary>
 /// The beoordeling use case (S-12): a behandelaar's decision on a registration. Goedkeuren sets the
 /// zaak's final status via the ACL (§8.1) and marks the aggregate INGESCHREVEN; Afwijzen marks it
-/// AFGEWEZEN in the domain (propagating a rejection to the zaak is a later sub-slice). Both are
-/// idempotent so a repeated or redelivered decision is a no-op.
+/// AFGEWEZEN. Either way the decision also completes the Flowable Beoordelen task (found by
+/// registrationId) so the process advances. All idempotent — a repeated decision is a no-op.
 /// </summary>
 public class BeoordeelRegistratieTests
 {
@@ -18,6 +18,9 @@ public class BeoordeelRegistratieTests
         return registration;
     }
 
+    private static FakeUserTaskClient TaskFor(Registration registration) =>
+        new([new BeoordelingTask("task-1", registration.Id)]);
+
     [Fact]
     public async Task Goedkeuren_sets_the_zaak_status_via_the_acl_and_marks_the_registration_ingeschreven()
     {
@@ -25,7 +28,8 @@ public class BeoordeelRegistratieTests
         var acl = new FakeAclClient();
         var registration = WithZaak();
         store.Seed(registration);
-        var handler = new BeoordeelRegistratie(store, acl);
+        var tasks = TaskFor(registration);
+        var handler = new BeoordeelRegistratie(store, acl, tasks);
 
         await handler.HandleAsync(new BeoordeelRegistratieCommand(registration.Id, BeoordelingsBesluit.Goedkeuren));
 
@@ -34,6 +38,8 @@ public class BeoordeelRegistratieTests
         Assert.Equal(FakeAclClient.DefaultZaakUrl, acl.ApprovedZaakUrl);
         Assert.Equal(1, acl.ApproveCallCount);
         Assert.Equal(1, store.SaveCount);
+        // The behandelaar's decision advances the workflow: the Beoordelen task is completed.
+        Assert.Equal(("task-1", BeoordelingsBesluit.Goedkeuren), tasks.Completed);
     }
 
     [Fact]
@@ -43,7 +49,8 @@ public class BeoordeelRegistratieTests
         var acl = new FakeAclClient();
         var registration = WithZaak();
         store.Seed(registration);
-        var handler = new BeoordeelRegistratie(store, acl);
+        var tasks = TaskFor(registration);
+        var handler = new BeoordeelRegistratie(store, acl, tasks);
 
         await handler.HandleAsync(new BeoordeelRegistratieCommand(registration.Id, BeoordelingsBesluit.Afwijzen));
 
@@ -51,6 +58,7 @@ public class BeoordeelRegistratieTests
         Assert.Equal(RegistrationStatus.Afgewezen, saved!.Status);
         Assert.Equal(0, acl.ApproveCallCount);
         Assert.Equal(1, store.SaveCount);
+        Assert.Equal(("task-1", BeoordelingsBesluit.Afwijzen), tasks.Completed);
     }
 
     [Fact]
@@ -61,7 +69,7 @@ public class BeoordeelRegistratieTests
         var registration = WithZaak();
         registration.TakeIntoBehandeling();
         store.Seed(registration);
-        var handler = new BeoordeelRegistratie(store, acl);
+        var handler = new BeoordeelRegistratie(store, acl, TaskFor(registration));
 
         await handler.HandleAsync(new BeoordeelRegistratieCommand(registration.Id, BeoordelingsBesluit.Goedkeuren));
 
@@ -73,7 +81,7 @@ public class BeoordeelRegistratieTests
     {
         var store = new FakeRegistrationStore();
         var acl = new FakeAclClient();
-        var handler = new BeoordeelRegistratie(store, acl);
+        var handler = new BeoordeelRegistratie(store, acl, new FakeUserTaskClient([]));
 
         await Assert.ThrowsAsync<ArgumentNullException>(() => handler.HandleAsync(null!));
         Assert.Equal(0, acl.ApproveCallCount);
@@ -85,7 +93,7 @@ public class BeoordeelRegistratieTests
     {
         var store = new FakeRegistrationStore();
         var acl = new FakeAclClient();
-        var handler = new BeoordeelRegistratie(store, acl);
+        var handler = new BeoordeelRegistratie(store, acl, new FakeUserTaskClient([]));
 
         var ex = await Assert.ThrowsAsync<InvalidOperationException>(() =>
             handler.HandleAsync(new BeoordeelRegistratieCommand(RegistrationId.New(), BeoordelingsBesluit.Goedkeuren)));
@@ -100,7 +108,7 @@ public class BeoordeelRegistratieTests
         var acl = new FakeAclClient();
         var registration = Registration.Submit("123456782"); // no zaak yet
         store.Seed(registration);
-        var handler = new BeoordeelRegistratie(store, acl);
+        var handler = new BeoordeelRegistratie(store, acl, TaskFor(registration));
 
         var ex = await Assert.ThrowsAsync<InvalidOperationException>(() =>
             handler.HandleAsync(new BeoordeelRegistratieCommand(registration.Id, BeoordelingsBesluit.Goedkeuren)));
@@ -115,7 +123,7 @@ public class BeoordeelRegistratieTests
         var acl = new FakeAclClient();
         var registration = WithZaak();
         store.Seed(registration);
-        var handler = new BeoordeelRegistratie(store, acl);
+        var handler = new BeoordeelRegistratie(store, acl, TaskFor(registration));
 
         await handler.HandleAsync(new BeoordeelRegistratieCommand(registration.Id, BeoordelingsBesluit.Goedkeuren));
         await handler.HandleAsync(new BeoordeelRegistratieCommand(registration.Id, BeoordelingsBesluit.Goedkeuren));
@@ -131,7 +139,7 @@ public class BeoordeelRegistratieTests
         var acl = new FakeAclClient();
         var registration = WithZaak();
         store.Seed(registration);
-        var handler = new BeoordeelRegistratie(store, acl);
+        var handler = new BeoordeelRegistratie(store, acl, TaskFor(registration));
 
         await handler.HandleAsync(new BeoordeelRegistratieCommand(registration.Id, BeoordelingsBesluit.Afwijzen));
         await handler.HandleAsync(new BeoordeelRegistratieCommand(registration.Id, BeoordelingsBesluit.Afwijzen));
@@ -139,4 +147,22 @@ public class BeoordeelRegistratieTests
         Assert.Equal(1, store.SaveCount);
         Assert.Equal(RegistrationStatus.Afgewezen, (await store.GetAsync(registration.Id))!.Status);
     }
+
+    [Fact]
+    public async Task Deciding_completes_no_task_when_none_is_open_for_the_registration()
+    {
+        // The task may already be gone (redelivery / manual completion). The decision still applies
+        // and simply completes nothing rather than failing.
+        var store = new FakeRegistrationStore();
+        var acl = new FakeAclClient();
+        var registration = WithZaak();
+        store.Seed(registration);
+        var tasks = new FakeUserTaskClient([]); // no open task for this registration
+        var handler = new BeoordeelRegistratie(store, acl, tasks);
+
+        await handler.HandleAsync(new BeoordeelRegistratieCommand(registration.Id, BeoordelingsBesluit.Goedkeuren));
+
+        Assert.Equal(RegistrationStatus.Ingeschreven, (await store.GetAsync(registration.Id))!.Status);
+        Assert.Null(tasks.Completed);
+    }
 }
diff --git a/tests/acceptance/Features/EenRegistratieBeoordelen.feature b/tests/acceptance/Features/EenRegistratieBeoordelen.feature
index 7c94fa6..1ff6aec 100644
--- a/tests/acceptance/Features/EenRegistratieBeoordelen.feature
+++ b/tests/acceptance/Features/EenRegistratieBeoordelen.feature
@@ -15,6 +15,7 @@ Feature: Een registratie beoordelen
     When the behandelaar decides "goedkeuren"
     Then the registration has status "INGESCHREVEN"
     And the zaak's final status is set via the ACL
+    And the beoordeling task is completed with "goedkeuren"
 
   Scenario: Afwijzen wijst de registratie af zonder de ACL
     Given a submitted registration with an opened zaak
@@ -22,3 +23,4 @@ Feature: Een registratie beoordelen
     And the behandelaar decides "afwijzen"
     Then the registration has status "AFGEWEZEN"
     And the ACL is not asked to set the zaak status
+    And the beoordeling task is completed with "afwijzen"
diff --git a/tests/acceptance/Steps/EenRegistratieBeoordelenSteps.cs b/tests/acceptance/Steps/EenRegistratieBeoordelenSteps.cs
index 181951d..39bfa3b 100644
--- a/tests/acceptance/Steps/EenRegistratieBeoordelenSteps.cs
+++ b/tests/acceptance/Steps/EenRegistratieBeoordelenSteps.cs
@@ -16,6 +16,7 @@ public sealed class EenRegistratieBeoordelenSteps
 {
     private readonly InMemoryAclClient _acl = new();
     private readonly InMemoryRegistrationStore _store = new();
+    private readonly InMemoryUserTaskClient _tasks = new();
     private RegistrationId _id;
 
     [Given("a submitted registration with an opened zaak")]
@@ -25,6 +26,8 @@ public sealed class EenRegistratieBeoordelenSteps
         registration.AttachZaak(InMemoryAclClient.OpenedZaakUrl);
         await _store.SaveAsync(registration);
         _id = registration.Id;
+        // The process has parked at the Beoordelen user task awaiting the behandelaar.
+        _tasks.Open(_id);
     }
 
     [When("the behandelaar takes it into behandeling")]
@@ -37,7 +40,7 @@ public sealed class EenRegistratieBeoordelenSteps
 
     [When("the behandelaar decides \"(.*)\"")]
     public async Task WhenTheBehandelaarDecides(string besluit)
-        => await new BeoordeelRegistratie(_store, _acl).HandleAsync(
+        => await new BeoordeelRegistratie(_store, _acl, _tasks).HandleAsync(
             new BeoordeelRegistratieCommand(_id, Enum.Parse<BeoordelingsBesluit>(besluit, ignoreCase: true)));
 
     [Then("the registration has status \"(.*)\"")]
@@ -55,4 +58,8 @@ public sealed class EenRegistratieBeoordelenSteps
     [Then("the ACL is not asked to set the zaak status")]
     public void ThenTheAclIsNotAskedToSetTheZaakStatus()
         => Assert.Null(_acl.ApprovedZaakUrl);
+
+    [Then("the beoordeling task is completed with \"(.*)\"")]
+    public void ThenTheBeoordelingTaskIsCompletedWith(string besluit)
+        => Assert.Equal(Enum.Parse<BeoordelingsBesluit>(besluit, ignoreCase: true), _tasks.Completed?.Besluit);
 }
diff --git a/tests/acceptance/Support/BffAcceptanceHost.cs b/tests/acceptance/Support/BffAcceptanceHost.cs
index 574a686..b574377 100644
--- a/tests/acceptance/Support/BffAcceptanceHost.cs
+++ b/tests/acceptance/Support/BffAcceptanceHost.cs
@@ -71,6 +71,9 @@ public sealed class CapturingDomainClient : IDomainClient
 
     public Task<IReadOnlyList<WerkbakItem>> GetWerkbakAsync(CancellationToken ct = default)
         => Task.FromResult<IReadOnlyList<WerkbakItem>>([]);
+
+    public Task DecideAsync(string registrationId, string besluit, CancellationToken ct = default)
+        => Task.CompletedTask;
 }
 
 /// <summary>Serves configurable projection rows.</summary>
diff --git a/tests/acceptance/Support/InMemoryDomainPorts.cs b/tests/acceptance/Support/InMemoryDomainPorts.cs
index fefb2e9..b5714ef 100644
--- a/tests/acceptance/Support/InMemoryDomainPorts.cs
+++ b/tests/acceptance/Support/InMemoryDomainPorts.cs
@@ -43,6 +43,29 @@ public sealed class InMemoryAclClient : IAclClient
     }
 }
 
+/// <summary>An in-memory user-task client for the beoordeling acceptance scenario: it holds one open
+/// Beoordelen task per registration and records the besluit each is completed with.</summary>
+public sealed class InMemoryUserTaskClient : IUserTaskClient
+{
+    private readonly List<BeoordelingTask> _open = [];
+
+    public (string TaskId, BeoordelingsBesluit Besluit)? Completed { get; private set; }
+
+    public void Open(RegistrationId registrationId) => _open.Add(new BeoordelingTask($"task-{registrationId}", registrationId));
+
+    public Task<IReadOnlyList<BeoordelingTask>> GetOpenBeoordelingenAsync(CancellationToken ct = default)
+        => Task.FromResult<IReadOnlyList<BeoordelingTask>>(_open);
+
+    public Task ClaimAsync(string taskId, string behandelaar, CancellationToken ct = default) => Task.CompletedTask;
+
+    public Task CompleteBeoordelingAsync(string taskId, BeoordelingsBesluit besluit, CancellationToken ct = default)
+    {
+        Completed = (taskId, besluit);
+        _open.RemoveAll(t => t.TaskId == taskId);
+        return Task.CompletedTask;
+    }
+}
+
 /// <summary>An in-memory registration store for the domain acceptance scenario.</summary>
 public sealed class InMemoryRegistrationStore : IRegistrationStore
 {