Merge pull request 'feat(bff): BFF with one endpoint per portal + OIDC validation (closes #8)' (#64) from feat/8-bff into main

Reviewed-on: #64

.gitea/workflows/ci.yaml

@@ -79,6 +79,13 @@ jobs:
           name: domain-mutation-report
           path: services/domain/StrykerOutput/**/reports/mutation-report.html
           if-no-files-found: warn
+      - uses: https://github.com/actions/upload-artifact@v3
+        if: always()
+        continue-on-error: true
+        with:
+          name: bff-mutation-report
+          path: services/bff/StrykerOutput/**/reports/mutation-report.html
+          if-no-files-found: warn
 
   # One stage for every check that needs the live stack. On the single self-hosted
   # runner jobs run sequentially, so booting OpenZaak once (instead of once per job)
@@ -101,6 +108,8 @@ jobs:
         run: make verify-projection
       - name: Domain → Flowable → ACL → OpenZaak
         run: make verify-domain
+      - name: BFF → Keycloak + domain + projection
+        run: make verify-bff
       # Log dump must precede teardown (which removes the containers).
       - name: Dump container logs on failure
         if: failure()

Makefile

@@ -64,14 +64,14 @@ unit:
 ## mutation: run the Stryker.NET ratchet on each service with branching logic (fails below baseline)
 # Stryker is pinned as a local dotnet tool (.config/dotnet-tools.json); `tool restore`
 # makes `make mutation` work from a fresh clone. Each service owns its config + break
-# threshold (the ratchet, CLAUDE.md §5): services/acl/stryker-config.json,
+# threshold (the ratchet, CLAUDE.md §5): each services/<svc>/stryker-config.json.
-# services/event-subscriber/stryker-config.json and services/domain/stryker-config.json.
 # Scores never regress below baseline.
 mutation:
 	dotnet tool restore
 	cd services/acl && dotnet stryker
 	cd services/event-subscriber && dotnet stryker
 	cd services/domain && dotnet stryker
+	cd services/bff && dotnet stryker
 
 ## smoke: seed config, bring the whole stack up, wait for health-checked services, tear down
 # SEED populates the external config volumes first (upstream images used verbatim;
@@ -143,6 +143,11 @@ verify-projection:
 verify-domain:
 	bash infra/run-domain-check.sh
 
+## verify-bff: BFF end-to-end (S-07) against the up stack — token validation on self-service
+## + anonymous public-safe openbaar register (ADR-0010).
+verify-bff:
+	bash infra/run-bff-check.sh
+
 ## verify: local mirror of the CI verify-stack job — full stack up once, all checks,
 ## tear down (always). For fast single-concern local iteration use `integration`
 ## (oz-only) or `verify-notifications` (oz+nrc) instead.
@@ -154,7 +159,8 @@ verify:
 	    && bash infra/run-acl-integration.sh \
 	    && bash infra/run-notification-check.sh \
 	    && bash infra/run-projection-check.sh \
-	    && bash infra/run-domain-check.sh || rc=$$?; \
+	    && bash infra/run-domain-check.sh \
+	    && bash infra/run-bff-check.sh || rc=$$?; \
 	  docker compose -f $(COMPOSE) down --volumes >/dev/null 2>&1; \
 	  docker volume rm -f $(CFG_VOLS) >/dev/null 2>&1; \
 	  exit $$rc'

docs/architecture/adr-0010-bff-oidc.md

@@ -0,0 +1,74 @@
+# ADR-0010: The BFF validates Keycloak tokens and is the portals' only backend
+
+- **Status:** Accepted
+- **Date:** 2026-07-01
+- **Deciders:** Respellion engineering
+- **Relates to:** S-07 (#8); proposal #63; builds on ADR-0001 (loose coupling, §8.3), S-02 (#3, Keycloak realms), S-05 (#6, Domain Service), S-06 (#7, read projection)
+
+## Context
+
+S-07 (#8) adds the **BFF (Backend-for-Frontend)** — the single backend the Angular portals talk
+to (CLAUDE.md §8.3). For the walking skeleton it exposes two endpoints and fans out to services
+already built:
+
+- `POST /self-service/registrations` → Domain Service `POST /registrations` (S-05).
+- `GET /openbaar/register?q=…` → projection-api `GET /register` (S-06).
+
+It must validate tokens issued by Keycloak (S-02). This is an ADR-worthy moment (§14): a new
+dependency (JWT bearer authentication) and two new service boundaries (BFF→domain, BFF→projection).
+
+## Decision
+
+**The BFF is the portals' only backend; it validates Keycloak `digid`-realm JWTs on the
+self-service endpoint, leaves the openbaar lookup anonymous, and fans out to the domain and
+projection over typed HTTP clients.**
+
+- **Auth model.** `POST /self-service/registrations` requires a valid `digid`-realm bearer token;
+  the BFF reads the `bsn` claim and forwards it to the domain. Missing / invalid / expired token →
+  **401**. `GET /openbaar/register` is **anonymous** — the openbaar register is a public lookup
+  (S-09), so no token is required.
+- **Portals talk only to the BFF (§8.3).** They never call the Domain Service, ACL, projection, or
+  OpenZaak directly. The BFF orchestrates via typed `HttpClient`s whose base URLs come from config.
+  Downstream calls are unauthenticated on the internal network for the walking skeleton; a
+  service-to-service auth story (e.g. client-credentials) is a later slice, not this one.
+- **Validation is `Microsoft.AspNetCore.Authentication.JwtBearer`** pointed at the Keycloak `digid`
+  realm authority. **New dependency justification:** it gives us standards-based OIDC/JWT validation
+  (signature, issuer, expiry, audience) maintained by the framework; rolling our own JWT validation
+  would be error-prone security code; the risk is a first-party ASP.NET Core package — minimal.
+- **Tests mint their own tokens.** `WebApplicationFactory` tests override the bearer options with a
+  **test signing key**, so valid / invalid / expired tokens are minted in-process without a live
+  Keycloak. Real Keycloak validation is exercised by a live-stack `verify-bff` check.
+- **OpenAPI is generated and committed** (`services/bff/openapi.json`) from .NET's built-in OpenAPI,
+  so S-08's Angular client is generated from the spec, never hand-written (§10).
+
+## Known wrinkle — container OIDC issuer mismatch
+
+Keycloak stamps tokens with an `iss` equal to its **browser-facing** URL (what the portal used to
+log in), which differs from the BFF's **in-container** authority (`http://keycloak:8080/realms/digid`).
+Strict issuer validation then rejects otherwise-valid tokens. Unit tests avoid this (test key).
+`verify-bff` handles it by aligning the configured authority/issuer with the token's `iss` (and, if
+needed, disabling metadata address rewriting). Recorded so it is not rediscovered each time.
+
+## Consequences
+
+- **Positive:** the walking skeleton gains its front door; §8.3 holds with all portal traffic going
+  through one backend; token validation is standard and testable without infra; the committed
+  OpenAPI unblocks S-08.
+- **Negative / deferred:**
+  - Downstream service-to-service auth is deferred (internal-network trust for now).
+  - The openbaar endpoint is anonymous; when public-safe field filtering tightens (S-09) it stays
+    anonymous but the projection query narrows.
+  - The issuer-mismatch handling is dev-oriented; a production reverse-proxy setup would align the
+    browser and internal issuer URLs instead.
+
+## Alternatives considered
+
+- **Token-gate the openbaar endpoint too** — rejected: the openbaar register is public by design
+  (S-09); requiring a login would contradict the slice's intent.
+- **Validate tokens by calling Keycloak's introspection endpoint per request** — rejected: adds a
+  network hop per call and a Keycloak dependency on the hot path; local JWT signature validation via
+  the realm's JWKS is the standard, faster choice.
+- **Hand-written JWT parsing** — rejected: security-sensitive code we shouldn't own when a
+  first-party validator exists.
+- **Generate the OpenAPI client by hand / keep the spec uncommitted** — rejected: §10 requires a
+  generated client from a committed spec.

docs/demo-script.md

@@ -5,6 +5,43 @@ copy-pasteable walkthrough against a local `make up` stack.
 
 ---
 
+## S-07 — BFF: the portals' single backend
+
+**Outcome:** the BFF validates Keycloak `digid` tokens on the self-service submit (forwarding the
+bsn to the domain) and serves the openbaar register anonymously with only public-safe fields — the
+front door the portals (S-08/S-09) will talk to.
+
+**The path:** portal → BFF `POST /self-service/registrations` (token-gated) → domain; and
+BFF `GET /openbaar/register` (anonymous) → projection-api. See ADR-0010.
+
+```bash
+# 1. Bring the full stack up.
+make up
+
+# 2. Drive the BFF end-to-end (401 without a token, 202 with a real digid token, anonymous openbaar).
+make verify-bff        # → "OK — BFF: 401 without token, 202 with a digid token, anonymous ..."
+
+# 3. Try it by hand (BFF on host port 8080).
+#    a) A digid access token for the mock user jan-burger (bsn 123456782):
+tok=$(curl -s -X POST http://localhost:8180/realms/digid/protocol/openid-connect/token \
+  -d grant_type=password -d client_id=big-portal -d username=jan-burger -d password=test123 \
+  | python3 -c "import sys,json;print(json.load(sys.stdin)['access_token'])")
+
+#    b) Submit — without the token it is 401; with it, 202:
+curl -s -o /dev/null -w "no token  -> %{http_code}\n" -X POST http://localhost:8080/self-service/registrations
+curl -s -o /dev/null -w "with token-> %{http_code}\n" -X POST http://localhost:8080/self-service/registrations \
+  -H "Authorization: Bearer $tok"
+
+#    c) The openbaar register is anonymous and exposes only id + status (never the bsn):
+curl -fsS http://localhost:8080/openbaar/register | jq
+```
+
+> The self-service token is validated against Keycloak's `digid` realm; the openbaar lookup needs no
+> token (S-09). The generated contract lives at `services/bff/openapi.json` — S-08's client is built
+> from it.
+
+---
+
 ## S-05 — BIG Domain Service: submit a registration
 
 **Outcome:** submitting a registration starts a Flowable process; the external-task worker

infra/docker-compose.yml

@@ -344,6 +344,13 @@ services:
       context: ../services/bff
       dockerfile: Dockerfile
     image: register-referentie/bff:dev
+    environment:
+      # The BFF is the portals' only backend; it validates digid tokens and fans out (ADR-0010).
+      # Keycloak (start-dev) derives the issuer from the request host, so the BFF authority and the
+      # verify token request both use keycloak:8080 to keep the issuer consistent.
+      Keycloak__Authority: http://keycloak:8080/realms/digid
+      Downstream__Domain__BaseUrl: http://domain:8080/
+      Downstream__Projection__BaseUrl: http://projection-api:8080/
     ports:
       - "8080:8080"
     healthcheck:
@@ -352,6 +359,13 @@ services:
       timeout: 3s
       retries: 5
       start_period: 10s
+    depends_on:
+      domain:
+        condition: service_healthy
+      projection-api:
+        condition: service_healthy
+      keycloak:
+        condition: service_started
     networks: [cg]
 
   # ── Read projection (S-06) ────────────────────────────────────────────────

infra/run-bff-check.sh

@@ -0,0 +1,58 @@
+#!/usr/bin/env bash
+#
+# Verify the BFF end-to-end (S-07) against an ALREADY-RUNNING full stack. The BFF is the portals'
+# only backend (§8.3): it validates Keycloak digid tokens on the self-service submit and serves the
+# openbaar register anonymously with only public-safe fields (ADR-0010).
+#
+# Checks, in-network (services reached by container IP; Keycloak by its service name so the token's
+# host-derived issuer matches the BFF's authority — see the compose bff env and ADR-0010):
+#   1. POST /self-service/registrations without a token            -> 401
+#   2. mint a real digid access token (direct grant) and POST it   -> 202 (forwarded to the domain)
+#   3. GET /openbaar/register (anonymous)                          -> 200 JSON array, never a bsn
+#
+# Does NOT manage the stack lifecycle (the caller owns bring-up + teardown). Plain docker primitives.
+set -euo pipefail
+
+ip() { docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' "$1"; }
+
+bff="$(docker ps -q --filter 'name=[-_]bff[-_]' | head -1)"
+kc="$(docker ps -q --filter 'name=keycloak' | head -1)"
+[ -n "$bff" ] || { echo "ERROR: no running bff container — bring the stack up first" >&2; exit 1; }
+[ -n "$kc" ] || { echo "ERROR: no running keycloak container — bring the stack up first" >&2; exit 1; }
+net="$(docker inspect -f '{{range $k,$_ := .NetworkSettings.Networks}}{{$k}}{{"\n"}}{{end}}' "$bff" | head -1)"
+bff_ip="$(ip "$bff")"
+echo ">> bff=$bff_ip network=$net"
+
+# Helper: run curl inside a throwaway container on the stack network (reaches services by name/IP).
+net_curl() { docker run --rm --network "$net" curlimages/curl:latest "$@"; }
+
+echo ">> 1. self-service submit without a token must be 401"
+code="$(net_curl -s -o /dev/null -w '%{http_code}' -X POST "http://$bff_ip:8080/self-service/registrations" \
+  -H 'Content-Type: application/json' -d '{}')"
+echo "   -> $code"; [ "$code" = "401" ] || { echo "FAIL: expected 401, got $code" >&2; exit 1; }
+
+echo ">> 2. minting a digid token (direct grant) via keycloak:8080 (host-consistent issuer)"
+token=""
+for _ in $(seq 1 20); do
+  token="$(net_curl -s -X POST "http://keycloak:8080/realms/digid/protocol/openid-connect/token" \
+    -H 'Content-Type: application/x-www-form-urlencoded' \
+    --data-urlencode 'grant_type=password' --data-urlencode 'client_id=big-portal' \
+    --data-urlencode 'username=jan-burger' --data-urlencode 'password=test123' \
+    | sed -n 's/.*"access_token":"\([^"]*\)".*/\1/p')"
+  [ -n "$token" ] && break
+  sleep 3
+done
+[ -n "$token" ] || { echo "FAIL: could not obtain a digid access token" >&2; exit 1; }
+echo "   -> got a token"
+
+echo ">> 2b. self-service submit with the token must be 202"
+code="$(net_curl -s -o /dev/null -w '%{http_code}' -X POST "http://$bff_ip:8080/self-service/registrations" \
+  -H "Authorization: Bearer $token" -H 'Content-Type: application/json' -d '{}')"
+echo "   -> $code"; [ "$code" = "202" ] || { echo "FAIL: expected 202, got $code" >&2; docker logs "$bff" 2>&1 | tail -15 >&2; exit 1; }
+
+echo ">> 3. openbaar register (anonymous) must be 200 JSON, never a bsn"
+body="$(net_curl -s "http://$bff_ip:8080/openbaar/register")"
+echo "$body" | grep -q '^\[' || { echo "FAIL: openbaar did not return a JSON array: $body" >&2; exit 1; }
+if echo "$body" | grep -q '"bsn"'; then echo "FAIL: openbaar leaked a bsn field" >&2; exit 1; fi
+
+echo "OK — BFF: 401 without token, 202 with a digid token, anonymous public-safe openbaar register"

mkdocs.yml

@@ -31,6 +31,7 @@ nav:
       - "ADR-0007: OpenZaak → NRC notification wiring": architecture/adr-0007-notification-wiring.md
       - "ADR-0008: Read projection store": architecture/adr-0008-read-projection-store.md
       - "ADR-0009: External-task job worker": architecture/adr-0009-external-task-job-worker.md
+      - "ADR-0010: BFF OIDC validation": architecture/adr-0010-bff-oidc.md
   - Working in Gitea: gitea-workflow.md
   - Demo script: demo-script.md
   - Runbooks:

services/bff/Bff.Api/Bff.Api.csproj

@@ -6,4 +6,10 @@
     <ImplicitUsings>enable</ImplicitUsings>
   </PropertyGroup>
 
+  <ItemGroup>
+    <!-- OIDC/JWT validation of Keycloak-issued tokens (ADR-0010) and OpenAPI generation. -->
+    <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="10.0.8" />
+    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="10.0.8" />
+  </ItemGroup>
+
 </Project>

services/bff/Bff.Api/DownstreamClients.cs

@@ -0,0 +1,47 @@
+using System.Net.Http.Json;
+
+namespace Bff.Api;
+
+/// <summary>What the self-service submit returns to the portal (the domain's registration id + status).</summary>
+public sealed record SubmitAccepted(string RegistrationId, string Status);
+
+/// <summary>A projection row as the projection-api serves it. <c>Bsn</c>/<c>NaamPlaceholder</c> are
+/// read but never surfaced by the openbaar endpoint (public-safe filtering, ADR-0010/S-09).</summary>
+public sealed record ProjectionEntry(string Id, string Status, string? Bsn, string? NaamPlaceholder);
+
+/// <summary>A public-safe openbaar register row — only non-sensitive fields leave the BFF.</summary>
+public sealed record OpenbaarEntry(string Id, string Status);
+
+/// <summary>Port to the Domain Service (§8.3: the BFF is the portals' only backend; it fans out).</summary>
+public interface IDomainClient
+{
+    Task<SubmitAccepted> SubmitRegistrationAsync(string bsn, CancellationToken ct = default);
+}
+
+/// <summary>Port to the read projection.</summary>
+public interface IProjectionClient
+{
+    Task<IReadOnlyList<ProjectionEntry>> GetRegisterAsync(CancellationToken ct = default);
+}
+
+/// <summary>Calls the Domain Service's <c>POST /registrations</c>.</summary>
+public sealed class DomainClient(HttpClient http) : IDomainClient
+{
+    public async Task<SubmitAccepted> SubmitRegistrationAsync(string bsn, CancellationToken ct = default)
+    {
+        using var response = await http.PostAsJsonAsync("registrations", new { bsn }, ct);
+        response.EnsureSuccessStatusCode();
+        var dto = await response.Content.ReadFromJsonAsync<DomainResponse>(ct)
+            ?? throw new InvalidOperationException("The Domain Service returned an empty registration response.");
+        return new SubmitAccepted(dto.RegistrationId, dto.Status);
+    }
+
+    private sealed record DomainResponse(string RegistrationId, string Status, string? ZaakUrl);
+}
+
+/// <summary>Calls the projection-api's <c>GET /register</c>.</summary>
+public sealed class ProjectionClient(HttpClient http) : IProjectionClient
+{
+    public async Task<IReadOnlyList<ProjectionEntry>> GetRegisterAsync(CancellationToken ct = default)
+        => await http.GetFromJsonAsync<List<ProjectionEntry>>("register", ct) ?? [];
+}

services/bff/Bff.Api/OpenbaarProjection.cs

@@ -0,0 +1,18 @@
+namespace Bff.Api;
+
+/// <summary>
+/// The public view of the read projection: filters rows by the openbaar search term and maps each to
+/// a public-safe <see cref="OpenbaarEntry"/> (only <c>id</c> + <c>status</c> — bsn/naam never leave the
+/// BFF). Pure so it is unit- and mutation-tested directly (ADR-0010).
+/// </summary>
+public static class OpenbaarProjection
+{
+    public static IReadOnlyList<OpenbaarEntry> PublicView(IReadOnlyList<ProjectionEntry> entries, string? q)
+    {
+        var filtered = string.IsNullOrWhiteSpace(q)
+            ? entries
+            : entries.Where(e => e.Id.Contains(q, StringComparison.OrdinalIgnoreCase));
+
+        return [.. filtered.Select(e => new OpenbaarEntry(e.Id, e.Status))];
+    }
+}

services/bff/Bff.Api/Program.cs

@@ -1,10 +1,72 @@
+using System.Security.Claims;
+using Bff.Api;
+using Microsoft.AspNetCore.Authentication.JwtBearer;
+
 var builder = WebApplication.CreateBuilder(args);
+
+var keycloakAuthority = builder.Configuration["Keycloak:Authority"]
+    ?? throw new InvalidOperationException("Missing configuration 'Keycloak:Authority'");
+var domainBaseUrl = builder.Configuration["Downstream:Domain:BaseUrl"]
+    ?? throw new InvalidOperationException("Missing configuration 'Downstream:Domain:BaseUrl'");
+var projectionBaseUrl = builder.Configuration["Downstream:Projection:BaseUrl"]
+    ?? throw new InvalidOperationException("Missing configuration 'Downstream:Projection:BaseUrl'");
+
+// Validate Keycloak-issued tokens (ADR-0010). Audience validation is off for the walking skeleton —
+// Keycloak's audience mapping is a later hardening; signature/issuer/expiry are validated.
+builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
+    .AddJwtBearer(options =>
+    {
+        options.Authority = keycloakAuthority;
+        options.RequireHttpsMetadata = false;
+        options.TokenValidationParameters.ValidateAudience = false;
+    });
+builder.Services.AddAuthorization();
+
+// The BFF is the portals' only backend; it fans out to the domain and projection (§8.3).
+builder.Services.AddHttpClient<IDomainClient, DomainClient>(c => c.BaseAddress = new Uri(domainBaseUrl));
+builder.Services.AddHttpClient<IProjectionClient, ProjectionClient>(c => c.BaseAddress = new Uri(projectionBaseUrl));
+
 builder.Services.AddHealthChecks();
+// Clear the auto-populated `servers` block so the committed spec is stable regardless of the host
+// the doc was generated from (the client sets its own base URL). Keeps the drift guard deterministic.
+builder.Services.AddOpenApi(options =>
+    options.AddDocumentTransformer((document, _, _) =>
+    {
+        document.Servers?.Clear();
+        return Task.CompletedTask;
+    }));
 
 var app = builder.Build();
 
-app.MapGet("/", () => "BFF placeholder");
+app.UseAuthentication();
+app.UseAuthorization();
+
 app.MapHealthChecks("/health");
+app.MapOpenApi();
+
+// Self-service submit: requires a valid digid token; the bsn comes from the token, not the body,
+// and is forwarded to the domain (ADR-0010). Returns 202 — the zaak is opened asynchronously (S-05).
+app.MapPost("/self-service/registrations", async (ClaimsPrincipal user, IDomainClient domain, CancellationToken ct) =>
+{
+    var bsn = user.FindFirstValue("bsn");
+    if (string.IsNullOrWhiteSpace(bsn))
+        return Results.BadRequest("The token carries no bsn claim.");
+
+    var accepted = await domain.SubmitRegistrationAsync(bsn, ct);
+    return Results.Accepted($"/self-service/registrations/{accepted.RegistrationId}", accepted);
+})
+    .RequireAuthorization()
+    .Produces<SubmitAccepted>(StatusCodes.Status202Accepted)
+    .Produces(StatusCodes.Status400BadRequest)
+    .Produces(StatusCodes.Status401Unauthorized);
+
+// Openbaar register: an anonymous public lookup that exposes only public-safe fields (S-09).
+app.MapGet("/openbaar/register", async (string? q, IProjectionClient projection, CancellationToken ct) =>
+{
+    var entries = await projection.GetRegisterAsync(ct);
+    return Results.Ok(OpenbaarProjection.PublicView(entries, q));
+})
+    .Produces<IReadOnlyList<OpenbaarEntry>>(StatusCodes.Status200OK);
 
 app.Run();
 

services/bff/Bff.Api/appsettings.json

@@ -5,5 +5,12 @@
       "Microsoft.AspNetCore": "Warning"
     }
   },
-  "AllowedHosts": "*"
+  "AllowedHosts": "*",
+  "Keycloak": {
+    "Authority": "http://localhost:8180/realms/digid"
+  },
+  "Downstream": {
+    "Domain": { "BaseUrl": "http://localhost:8130/" },
+    "Projection": { "BaseUrl": "http://localhost:8120/" }
+  }
 }

services/bff/Bff.Tests/BffFactory.cs

@@ -0,0 +1,78 @@
+using System.Text;
+using Bff.Api;
+using Microsoft.AspNetCore.Authentication.JwtBearer;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.AspNetCore.TestHost;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.IdentityModel.Protocols.OpenIdConnect;
+using Microsoft.IdentityModel.Tokens;
+
+namespace Bff.Tests;
+
+/// <summary>
+/// Test host for the BFF. It swaps the downstream clients for in-memory fakes and reconfigures the
+/// JWT bearer to validate against a local test key (no live Keycloak) — so token validation is
+/// exercised in-process with tokens the tests mint (ADR-0010).
+/// </summary>
+internal sealed class BffFactory : WebApplicationFactory<Program>
+{
+    public static readonly SymmetricSecurityKey TestSigningKey =
+        new(Encoding.UTF8.GetBytes("bff-test-signing-key-that-is-at-least-256-bits-long!"));
+
+    public FakeDomainClient Domain { get; } = new();
+    public FakeProjectionClient Projection { get; } = new();
+
+    protected override void ConfigureWebHost(IWebHostBuilder builder)
+    {
+        builder.UseSetting("Keycloak:Authority", "https://keycloak.invalid/realms/digid");
+        builder.UseSetting("Downstream:Domain:BaseUrl", "http://domain.invalid/");
+        builder.UseSetting("Downstream:Projection:BaseUrl", "http://projection.invalid/");
+
+        builder.ConfigureTestServices(services =>
+        {
+            services.AddSingleton<IDomainClient>(Domain);
+            services.AddSingleton<IProjectionClient>(Projection);
+
+            services.Configure<JwtBearerOptions>(JwtBearerDefaults.AuthenticationScheme, options =>
+            {
+                // Validate locally against the test key; never reach out for OIDC metadata.
+                options.Authority = null;
+                options.MetadataAddress = null!;
+                options.RequireHttpsMetadata = false;
+                options.Configuration = new OpenIdConnectConfiguration();
+                options.TokenValidationParameters = new TokenValidationParameters
+                {
+                    ValidateIssuer = false,
+                    ValidateAudience = false,
+                    ValidateLifetime = true,
+                    ValidateIssuerSigningKey = true,
+                    IssuerSigningKey = TestSigningKey,
+                    ClockSkew = TimeSpan.Zero,
+                };
+            });
+        });
+    }
+}
+
+/// <summary>Captures the bsn the BFF forwarded and returns a canned acceptance.</summary>
+internal sealed class FakeDomainClient : IDomainClient
+{
+    public string? SubmittedBsn { get; private set; }
+    public SubmitAccepted Result { get; set; } = new("reg-123", "Ingediend");
+
+    public Task<SubmitAccepted> SubmitRegistrationAsync(string bsn, CancellationToken ct = default)
+    {
+        SubmittedBsn = bsn;
+        return Task.FromResult(Result);
+    }
+}
+
+/// <summary>Serves a configurable set of projection rows.</summary>
+internal sealed class FakeProjectionClient : IProjectionClient
+{
+    public List<ProjectionEntry> Entries { get; } = [];
+
+    public Task<IReadOnlyList<ProjectionEntry>> GetRegisterAsync(CancellationToken ct = default)
+        => Task.FromResult<IReadOnlyList<ProjectionEntry>>(Entries);
+}

services/bff/Bff.Tests/OpenApiSpecTests.cs

@@ -0,0 +1,34 @@
+using System.Runtime.CompilerServices;
+using System.Text.Json;
+
+namespace Bff.Tests;
+
+/// <summary>
+/// Guards the committed OpenAPI contract (<c>services/bff/openapi.json</c>) against drift: it must
+/// equal the document the running BFF serves. S-08's Angular client is generated from this file, so a
+/// stale spec is a bug. To regenerate: run the BFF and save <c>/openapi/v1.json</c> over the file.
+/// </summary>
+public class OpenApiSpecTests
+{
+    [Fact]
+    public async Task Committed_openapi_spec_matches_the_served_document()
+    {
+        using var factory = new BffFactory();
+
+        var served = await factory.CreateClient().GetStringAsync("/openapi/v1.json");
+        var committed = await File.ReadAllTextAsync(SpecPath());
+
+        Assert.Equal(Canonical(committed), Canonical(served));
+    }
+
+    // Reformat both sides identically so the comparison is about content, not whitespace.
+    private static string Canonical(string json)
+    {
+        using var doc = JsonDocument.Parse(json);
+        return JsonSerializer.Serialize(doc.RootElement, new JsonSerializerOptions { WriteIndented = true });
+    }
+
+    // The committed spec sits at services/bff/openapi.json — one level up from this test file.
+    private static string SpecPath([CallerFilePath] string thisFile = "")
+        => Path.Combine(Path.GetDirectoryName(thisFile)!, "..", "openapi.json");
+}

services/bff/Bff.Tests/OpenbaarEndpointTests.cs

@@ -0,0 +1,38 @@
+using System.Net;
+using System.Net.Http.Json;
+using Bff.Api;
+
+namespace Bff.Tests;
+
+public class OpenbaarEndpointTests
+{
+    [Fact]
+    public async Task Serves_public_safe_rows_anonymously()
+    {
+        using var factory = new BffFactory();
+        factory.Projection.Entries.Add(new ProjectionEntry("abc-111", "INGEDIEND", "123456782", "Jan"));
+
+        // No Authorization header — the openbaar register is a public lookup (ADR-0010/S-09).
+        var response = await factory.CreateClient().GetAsync("/openbaar/register");
+
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        var body = await response.Content.ReadAsStringAsync();
+        Assert.Contains("abc-111", body);
+        Assert.Contains("INGEDIEND", body);
+        // The bsn must never appear in a public response.
+        Assert.DoesNotContain("123456782", body);
+    }
+
+    [Fact]
+    public async Task Filters_by_the_query_parameter()
+    {
+        using var factory = new BffFactory();
+        factory.Projection.Entries.Add(new ProjectionEntry("abc-111", "INGEDIEND", null, null));
+        factory.Projection.Entries.Add(new ProjectionEntry("def-222", "INGEDIEND", null, null));
+
+        var rows = await factory.CreateClient()
+            .GetFromJsonAsync<List<OpenbaarEntry>>("/openbaar/register?q=abc");
+
+        Assert.Equal("abc-111", Assert.Single(rows!).Id);
+    }
+}

services/bff/Bff.Tests/OpenbaarProjectionTests.cs

@@ -0,0 +1,48 @@
+using Bff.Api;
+
+namespace Bff.Tests;
+
+public class OpenbaarProjectionTests
+{
+    private static readonly ProjectionEntry[] Sample =
+    [
+        new("abc-111", "INGEDIEND", "123456782", "Jan"),
+        new("def-222", "INGEDIEND", "987654321", "Piet"),
+    ];
+
+    [Fact]
+    public void Maps_every_row_to_public_safe_fields_when_no_query()
+    {
+        var view = OpenbaarProjection.PublicView(Sample, null);
+
+        Assert.Equal(2, view.Count);
+        Assert.Equal("abc-111", view[0].Id);
+        Assert.Equal("INGEDIEND", view[0].Status);
+    }
+
+    [Fact]
+    public void Public_view_exposes_only_id_and_status()
+    {
+        // OpenbaarEntry structurally carries only Id + Status — bsn/naam can never leak.
+        var props = typeof(OpenbaarEntry).GetProperties().Select(p => p.Name).ToArray();
+        Assert.Equal(["Id", "Status"], props);
+    }
+
+    [Theory]
+    [InlineData("abc", 1)]
+    [InlineData("ABC", 1)]
+    [InlineData("2", 1)]
+    [InlineData("zzz", 0)]
+    public void Filters_by_id_containing_the_query_case_insensitively(string q, int expected)
+    {
+        var view = OpenbaarProjection.PublicView(Sample, q);
+
+        Assert.Equal(expected, view.Count);
+    }
+
+    [Fact]
+    public void Blank_query_is_treated_as_no_filter()
+    {
+        Assert.Equal(2, OpenbaarProjection.PublicView(Sample, "   ").Count);
+    }
+}

services/bff/Bff.Tests/SelfServiceEndpointTests.cs

@@ -0,0 +1,75 @@
+using System.Net;
+using System.Net.Http.Headers;
+using System.Net.Http.Json;
+
+namespace Bff.Tests;
+
+public class SelfServiceEndpointTests
+{
+    private static HttpRequestMessage Submit(string? bearer)
+    {
+        var request = new HttpRequestMessage(HttpMethod.Post, "/self-service/registrations")
+        {
+            Content = JsonContent.Create(new { }),
+        };
+        if (bearer is not null)
+            request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", bearer);
+        return request;
+    }
+
+    [Fact]
+    public async Task Rejects_a_request_without_a_token()
+    {
+        using var factory = new BffFactory();
+        var client = factory.CreateClient();
+
+        var response = await client.SendAsync(Submit(bearer: null));
+
+        Assert.Equal(HttpStatusCode.Unauthorized, response.StatusCode);
+        Assert.Null(factory.Domain.SubmittedBsn);
+    }
+
+    [Theory]
+    [InlineData("not-a-jwt")]
+    public async Task Rejects_a_malformed_token(string bearer)
+    {
+        using var factory = new BffFactory();
+        var response = await factory.CreateClient().SendAsync(Submit(bearer));
+
+        Assert.Equal(HttpStatusCode.Unauthorized, response.StatusCode);
+    }
+
+    [Fact]
+    public async Task Rejects_a_token_signed_with_the_wrong_key()
+    {
+        using var factory = new BffFactory();
+        var response = await factory.CreateClient().SendAsync(Submit(TestTokens.WrongKey("123456782")));
+
+        Assert.Equal(HttpStatusCode.Unauthorized, response.StatusCode);
+    }
+
+    [Fact]
+    public async Task Rejects_an_expired_token()
+    {
+        using var factory = new BffFactory();
+        var response = await factory.CreateClient().SendAsync(Submit(TestTokens.Expired("123456782")));
+
+        Assert.Equal(HttpStatusCode.Unauthorized, response.StatusCode);
+    }
+
+    [Fact]
+    public async Task Accepts_a_valid_token_and_forwards_the_bsn_to_the_domain()
+    {
+        using var factory = new BffFactory();
+        var client = factory.CreateClient();
+
+        var response = await client.SendAsync(Submit(TestTokens.Valid("123456782")));
+
+        Assert.Equal(HttpStatusCode.Accepted, response.StatusCode);
+        Assert.Equal("123456782", factory.Domain.SubmittedBsn);
+        var body = await response.Content.ReadFromJsonAsync<SubmitAcceptedDto>();
+        Assert.Equal("reg-123", body!.RegistrationId);
+    }
+
+    private sealed record SubmitAcceptedDto(string RegistrationId, string Status);
+}

services/bff/Bff.Tests/TestTokens.cs

@@ -0,0 +1,30 @@
+using System.Text;
+using Microsoft.IdentityModel.JsonWebTokens;
+using Microsoft.IdentityModel.Tokens;
+
+namespace Bff.Tests;
+
+/// <summary>Mints JWTs for the BFF tests — signed with the factory's test key (valid) or otherwise
+/// (a wrong key / expired) to exercise the bearer validation the BFF configures.</summary>
+internal static class TestTokens
+{
+    public static string Valid(string bsn) => Create(bsn, BffFactory.TestSigningKey, expired: false);
+
+    public static string Expired(string bsn) => Create(bsn, BffFactory.TestSigningKey, expired: true);
+
+    public static string WrongKey(string bsn) => Create(
+        bsn,
+        new SymmetricSecurityKey(Encoding.UTF8.GetBytes("a-different-signing-key-256-bits-long-indeed-yes!")),
+        expired: false);
+
+    private static string Create(string bsn, SymmetricSecurityKey key, bool expired)
+    {
+        var handler = new JsonWebTokenHandler();
+        return handler.CreateToken(new SecurityTokenDescriptor
+        {
+            Claims = new Dictionary<string, object> { ["bsn"] = bsn },
+            Expires = DateTime.UtcNow.AddMinutes(expired ? -5 : 30),
+            SigningCredentials = new SigningCredentials(key, SecurityAlgorithms.HmacSha256),
+        });
+    }
+}

services/bff/openapi.json

@@ -0,0 +1,104 @@
+{
+  "openapi": "3.1.1",
+  "info": {
+    "title": "Bff.Api | v1",
+    "version": "1.0.0"
+  },
+  "paths": {
+    "/self-service/registrations": {
+      "post": {
+        "tags": [
+          "Bff.Api"
+        ],
+        "responses": {
+          "202": {
+            "description": "Accepted",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/SubmitAccepted"
+                }
+              }
+            }
+          },
+          "400": {
+            "description": "Bad Request"
+          },
+          "401": {
+            "description": "Unauthorized"
+          }
+        }
+      }
+    },
+    "/openbaar/register": {
+      "get": {
+        "tags": [
+          "Bff.Api"
+        ],
+        "parameters": [
+          {
+            "name": "q",
+            "in": "query",
+            "schema": {
+              "type": "string"
+            }
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "OK",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "array",
+                  "items": {
+                    "$ref": "#/components/schemas/OpenbaarEntry"
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  },
+  "components": {
+    "schemas": {
+      "OpenbaarEntry": {
+        "required": [
+          "id",
+          "status"
+        ],
+        "type": "object",
+        "properties": {
+          "id": {
+            "type": "string"
+          },
+          "status": {
+            "type": "string"
+          }
+        }
+      },
+      "SubmitAccepted": {
+        "required": [
+          "registrationId",
+          "status"
+        ],
+        "type": "object",
+        "properties": {
+          "registrationId": {
+            "type": "string"
+          },
+          "status": {
+            "type": "string"
+          }
+        }
+      }
+    }
+  },
+  "tags": [
+    {
+      "name": "Bff.Api"
+    }
+  ]
+}

services/bff/stryker-config.json

@@ -0,0 +1,16 @@
+{
+  "stryker-config": {
+    "solution": "Bff.slnx",
+    "test-projects": ["Bff.Tests/Bff.Tests.csproj"],
+    "reporters": ["progress", "html"],
+    "mutate": [
+      "!**/Program.cs",
+      "!**/DownstreamClients.cs"
+    ],
+    "thresholds": {
+      "high": 95,
+      "low": 90,
+      "break": 90
+    }
+  }
+}

tests/acceptance/Acceptance.csproj

@@ -9,6 +9,8 @@
 
   <ItemGroup>
     <PackageReference Include="coverlet.collector" Version="6.0.4" />
+    <!-- The BFF acceptance scenario drives the real HTTP endpoints in-process (ADR-0010). -->
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="10.0.8" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
     <PackageReference Include="Reqnroll.xUnit" Version="3.3.4" />
     <PackageReference Include="xunit" Version="2.9.3" />
@@ -20,6 +22,7 @@
     <ProjectReference Include="..\..\services\acl\Acl.Infrastructure\Acl.Infrastructure.csproj" />
     <ProjectReference Include="..\..\services\event-subscriber\EventSubscriber.Application\EventSubscriber.Application.csproj" />
     <ProjectReference Include="..\..\services\domain\Big.Application\Big.Application.csproj" />
+    <ProjectReference Include="..\..\services\bff\Bff.Api\Bff.Api.csproj" />
   </ItemGroup>
 
 </Project>

tests/acceptance/Features/BffToegang.feature

@@ -0,0 +1,22 @@
+# language: en
+# Drives S-07 (#8). The BFF is the portals' only backend (§8.3): it validates Keycloak digid tokens
+# on the self-service submit and serves the openbaar register anonymously with only public-safe
+# fields (ADR-0010). Tokens are minted with a local test key; real Keycloak validation is verify-bff.
+Feature: Toegang via de BFF
+  Als portaal wil ik uitsluitend via de BFF met de backend praten
+  zodat tokenvalidatie en veilige velden centraal geregeld zijn.
+
+  Scenario: Indienen met een geldig token wordt doorgezet naar het domein
+    Given a zorgprofessional with a valid DigiD token for BSN "123456782"
+    When they submit a registration via the BFF
+    Then the BFF accepts it and forwards BSN "123456782" to the domain
+
+  Scenario: Indienen zonder token wordt geweigerd
+    Given a caller without a token
+    When they submit a registration via the BFF
+    Then the BFF rejects it as unauthorized
+
+  Scenario: Het openbaar register is anoniem en toont geen BSN
+    Given the projection contains a zaak "abc-111" for BSN "123456782"
+    When the openbaar register is queried anonymously
+    Then the response lists "abc-111" without exposing the BSN

tests/acceptance/Steps/BffToegangSteps.cs

@@ -0,0 +1,83 @@
+using System.Net;
+using System.Net.Http.Headers;
+using System.Net.Http.Json;
+using Acceptance.Support;
+using Bff.Api;
+using Reqnroll;
+using Xunit;
+
+namespace Acceptance.Steps;
+
+/// <summary>Bindings for <c>BffToegang.feature</c> (S-07). Drives the real BFF over HTTP with a
+/// fake domain + projection and locally-minted tokens (ADR-0010). One host per scenario.</summary>
+[Binding]
+public sealed class BffToegangSteps : IDisposable
+{
+    private readonly BffAcceptanceHost _host = new();
+    private HttpClient _client = null!;
+    private string? _token;
+    private HttpResponseMessage? _response;
+
+    [Given("a zorgprofessional with a valid DigiD token for BSN \"(.*)\"")]
+    public void GivenAValidToken(string bsn)
+    {
+        _token = BffAcceptanceHost.MintToken(bsn);
+        _client = _host.CreateClient();
+    }
+
+    [Given("a caller without a token")]
+    public void GivenNoToken() => _client = _host.CreateClient();
+
+    [Given("the projection contains a zaak \"(.*)\" for BSN \"(.*)\"")]
+    public void GivenTheProjectionContains(string zaakId, string bsn)
+    {
+        _host.Projection.Entries.Add(new ProjectionEntry(zaakId, "INGEDIEND", bsn, null));
+        _client = _host.CreateClient();
+    }
+
+    [When("they submit a registration via the BFF")]
+    public async Task WhenTheySubmit()
+    {
+        var request = new HttpRequestMessage(HttpMethod.Post, "/self-service/registrations")
+        {
+            Content = JsonContent.Create(new { }),
+        };
+        if (_token is not null)
+            request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", _token);
+        _response = await _client.SendAsync(request);
+    }
+
+    [When("the openbaar register is queried anonymously")]
+    public async Task WhenTheOpenbaarRegisterIsQueried()
+        => _response = await _client.GetAsync("/openbaar/register");
+
+    [Then("the BFF accepts it and forwards BSN \"(.*)\" to the domain")]
+    public void ThenAcceptedAndForwarded(string bsn)
+    {
+        Assert.Equal(HttpStatusCode.Accepted, _response!.StatusCode);
+        Assert.Equal(bsn, _host.Domain.SubmittedBsn);
+    }
+
+    [Then("the BFF rejects it as unauthorized")]
+    public void ThenUnauthorized()
+    {
+        Assert.Equal(HttpStatusCode.Unauthorized, _response!.StatusCode);
+        Assert.Null(_host.Domain.SubmittedBsn);
+    }
+
+    [Then("the response lists \"(.*)\" without exposing the BSN")]
+    public async Task ThenListsWithoutBsn(string zaakId)
+    {
+        Assert.Equal(HttpStatusCode.OK, _response!.StatusCode);
+        var body = await _response.Content.ReadAsStringAsync();
+        Assert.Contains(zaakId, body);
+        Assert.DoesNotContain("123456782", body);
+    }
+
+    public void Dispose()
+    {
+        _response?.Dispose();
+        _client?.Dispose();
+        _host.Dispose();
+    }
+}

tests/acceptance/Support/BffAcceptanceHost.cs

@@ -0,0 +1,80 @@
+using System.Text;
+using Bff.Api;
+using Microsoft.AspNetCore.Authentication.JwtBearer;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.AspNetCore.TestHost;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.IdentityModel.JsonWebTokens;
+using Microsoft.IdentityModel.Protocols.OpenIdConnect;
+using Microsoft.IdentityModel.Tokens;
+
+namespace Acceptance.Support;
+
+/// <summary>Hosts the real BFF in-process for the acceptance scenario, with fake downstreams and a
+/// local test signing key so tokens can be minted without a live Keycloak (ADR-0010).</summary>
+public sealed class BffAcceptanceHost : WebApplicationFactory<Program>
+{
+    private static readonly SymmetricSecurityKey TestKey =
+        new(Encoding.UTF8.GetBytes("acceptance-bff-signing-key-at-least-256-bits-long!!"));
+
+    public CapturingDomainClient Domain { get; } = new();
+    public StubProjectionClient Projection { get; } = new();
+
+    public static string MintToken(string bsn) => new JsonWebTokenHandler().CreateToken(new SecurityTokenDescriptor
+    {
+        Claims = new Dictionary<string, object> { ["bsn"] = bsn },
+        Expires = DateTime.UtcNow.AddMinutes(30),
+        SigningCredentials = new SigningCredentials(TestKey, SecurityAlgorithms.HmacSha256),
+    });
+
+    protected override void ConfigureWebHost(IWebHostBuilder builder)
+    {
+        builder.UseSetting("Keycloak:Authority", "https://keycloak.invalid/realms/digid");
+        builder.UseSetting("Downstream:Domain:BaseUrl", "http://domain.invalid/");
+        builder.UseSetting("Downstream:Projection:BaseUrl", "http://projection.invalid/");
+
+        builder.ConfigureTestServices(services =>
+        {
+            services.AddSingleton<IDomainClient>(Domain);
+            services.AddSingleton<IProjectionClient>(Projection);
+            services.Configure<JwtBearerOptions>(JwtBearerDefaults.AuthenticationScheme, options =>
+            {
+                options.Authority = null;
+                options.MetadataAddress = null!;
+                options.RequireHttpsMetadata = false;
+                options.Configuration = new OpenIdConnectConfiguration();
+                options.TokenValidationParameters = new TokenValidationParameters
+                {
+                    ValidateIssuer = false,
+                    ValidateAudience = false,
+                    ValidateLifetime = true,
+                    ValidateIssuerSigningKey = true,
+                    IssuerSigningKey = TestKey,
+                    ClockSkew = TimeSpan.Zero,
+                };
+            });
+        });
+    }
+}
+
+/// <summary>Records the bsn the BFF forwarded.</summary>
+public sealed class CapturingDomainClient : IDomainClient
+{
+    public string? SubmittedBsn { get; private set; }
+
+    public Task<SubmitAccepted> SubmitRegistrationAsync(string bsn, CancellationToken ct = default)
+    {
+        SubmittedBsn = bsn;
+        return Task.FromResult(new SubmitAccepted("reg-acc-1", "Ingediend"));
+    }
+}
+
+/// <summary>Serves configurable projection rows.</summary>
+public sealed class StubProjectionClient : IProjectionClient
+{
+    public List<ProjectionEntry> Entries { get; } = [];
+
+    public Task<IReadOnlyList<ProjectionEntry>> GetRegisterAsync(CancellationToken ct = default)
+        => Task.FromResult<IReadOnlyList<ProjectionEntry>>(Entries);
+}