.config/dotnet-tools.json

@@ -8,6 +8,13 @@
         "dotnet-stryker"
       ],
       "rollForward": false
+    },
+    "dotnet-ef": {
+      "version": "10.0.0",
+      "commands": [
+        "dotnet-ef"
+      ],
+      "rollForward": false
     }
   }
 }

register-referentie.slnx

@@ -12,9 +12,14 @@
     <Project Path="services/bff/Bff.Tests/Bff.Tests.csproj" />
   </Folder>
   <Folder Name="/services/event-subscriber/">
+    <Project Path="services/event-subscriber/EventSubscriber.Api/EventSubscriber.Api.csproj" />
     <Project Path="services/event-subscriber/EventSubscriber.Application/EventSubscriber.Application.csproj" />
     <Project Path="services/event-subscriber/EventSubscriber.Tests/EventSubscriber.Tests.csproj" />
   </Folder>
+  <Folder Name="/services/projection-api/">
+    <Project Path="services/projection-api/Projection.ReadModel/Projection.ReadModel.csproj" />
+    <Project Path="services/projection-api/ProjectionApi.Api/ProjectionApi.Api.csproj" />
+  </Folder>
   <Folder Name="/tests/">
     <Project Path="tests/acceptance/Acceptance.csproj" />
   </Folder>

services/event-subscriber/EventSubscriber.Api/EventSubscriber.Api.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <ItemGroup>
+    <ProjectReference Include="..\EventSubscriber.Application\EventSubscriber.Application.csproj" />
+    <ProjectReference Include="..\..\projection-api\Projection.ReadModel\Projection.ReadModel.csproj" />
+  </ItemGroup>
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+</Project>

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

@@ -0,0 +1,56 @@
+using EventSubscriber.Application;
+using Projection.ReadModel;
+
+var builder = WebApplication.CreateBuilder(args);
+
+var connectionString = builder.Configuration.GetConnectionString("Projection")
+    ?? throw new InvalidOperationException("Missing connection string 'ConnectionStrings:Projection'");
+// The exact Authorization header value Open Notificaties sends on each abonnement callback.
+// NRC probes the callback during registration and refuses it unless it returns 401 without
+// this value (ADR-0007), so the webhook enforces it.
+var webhookToken = builder.Configuration["EventSubscriber:Webhook:AuthToken"]
+    ?? throw new InvalidOperationException("Missing configuration 'EventSubscriber:Webhook:AuthToken'");
+
+builder.Services.AddProjectionReadModel(connectionString);
+builder.Services.AddProjectionWriteSide();
+
+var app = builder.Build();
+
+// Apply migrations on start so a fresh stack reaches a usable schema unattended.
+await app.Services.MigrateProjectionAsync();
+
+app.MapGet("/health", () => "Healthy");
+
+// The NRC abonnement callback. Open Notificaties POSTs a notification here; we project it.
+// Auth-on-callback is mandatory: without the configured Authorization, return 401 (NRC's
+// registration probe depends on this — ADR-0007).
+app.MapPost("/notifications", async (
+    HttpRequest request,
+    NotificationDto body,
+    NotificationProjector projector,
+    CancellationToken ct) =>
+{
+    if (request.Headers.Authorization != webhookToken)
+        return Results.Unauthorized();
+
+    await projector.HandleAsync(body.ToNotification(), ct);
+    return Results.NoContent();
+});
+
+// Admin: rebuild the projection from the durable notification log (PRD §8.4 — rebuildable).
+app.MapPost("/admin/rebuild", async (NotificationProjector projector, CancellationToken ct) =>
+{
+    await projector.RebuildAsync(ct);
+    return Results.NoContent();
+});
+
+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 Notification ToNotification() => new(Kanaal, Resource, Actie, ResourceUrl);
+}
+
+public partial class Program;

services/event-subscriber/EventSubscriber.Api/appsettings.json

@@ -0,0 +1,8 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}

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

@@ -0,0 +1,18 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Design;
+
+namespace Projection.ReadModel;
+
+/// <summary>Lets <c>dotnet ef migrations</c> build the context at design time without a running
+/// database or the host's DI. The connection string is a placeholder — migrations only need the
+/// provider to emit Postgres-shaped SQL.</summary>
+public sealed class DesignTimeProjectionDbContextFactory : IDesignTimeDbContextFactory<ProjectionDbContext>
+{
+    public ProjectionDbContext CreateDbContext(string[] args)
+    {
+        var options = new DbContextOptionsBuilder<ProjectionDbContext>()
+            .UseNpgsql("Host=localhost;Database=projection;Username=projection;Password=projection")
+            .Options;
+        return new ProjectionDbContext(options);
+    }
+}

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

@@ -0,0 +1,39 @@
+using EventSubscriber.Application;
+using Microsoft.EntityFrameworkCore;
+
+namespace Projection.ReadModel;
+
+/// <summary>EF Core implementation of the notification log. Idempotency is enforced atomically
+/// by the primary key on <c>key</c>: a duplicate insert raises a unique violation, which is
+/// caught and reported as "already recorded" rather than failing the request.</summary>
+public sealed class EfNotificationLog(ProjectionDbContext db) : INotificationLog
+{
+    public async Task<bool> TryRecordAsync(RecordedNotification notification, CancellationToken ct = default)
+    {
+        db.ProcessedNotifications.Add(new ProcessedNotificationRow
+        {
+            Key = notification.Key,
+            Actie = notification.Actie,
+            ZaakId = notification.ZaakId,
+            ReceivedAt = DateTimeOffset.UtcNow,
+        });
+
+        try
+        {
+            await db.SaveChangesAsync(ct);
+            return true;
+        }
+        catch (DbUpdateException)
+        {
+            // Already recorded by an earlier (or concurrent) delivery — drop this duplicate.
+            db.ChangeTracker.Clear();
+            return false;
+        }
+    }
+
+    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))
+            .ToListAsync(ct);
+}

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

@@ -0,0 +1,40 @@
+using EventSubscriber.Application;
+using Microsoft.EntityFrameworkCore;
+
+namespace Projection.ReadModel;
+
+/// <summary>EF Core implementation of the projection store over <see cref="ProjectionDbContext"/>.</summary>
+public sealed class EfProjectionStore(ProjectionDbContext db) : IProjectionStore
+{
+    public async Task UpsertAsync(RegisterEntry entry, CancellationToken ct = default)
+    {
+        var row = await db.RegisterEntries.FindAsync([entry.Id], ct);
+        if (row is null)
+        {
+            db.RegisterEntries.Add(new RegisterEntryRow
+            {
+                Id = entry.Id,
+                Status = entry.Status,
+                Bsn = entry.Bsn,
+                NaamPlaceholder = entry.NaamPlaceholder,
+            });
+        }
+        else
+        {
+            row.Status = entry.Status;
+            row.Bsn = entry.Bsn;
+            row.NaamPlaceholder = entry.NaamPlaceholder;
+        }
+
+        await db.SaveChangesAsync(ct);
+    }
+
+    public async Task ClearAsync(CancellationToken ct = default)
+        => await db.RegisterEntries.ExecuteDeleteAsync(ct);
+
+    public async Task<IReadOnlyList<RegisterEntry>> AllAsync(CancellationToken ct = default)
+        => await db.RegisterEntries
+            .OrderBy(r => r.Id)
+            .Select(r => new RegisterEntry(r.Id, r.Status, r.Bsn, r.NaamPlaceholder))
+            .ToListAsync(ct);
+}

services/projection-api/Projection.ReadModel/Migrations/20260630125055_InitialProjection.Designer.cs

@@ -0,0 +1,79 @@
+// <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("20260630125055_InitialProjection")]
+    partial class InitialProjection
+    {
+        /// <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>("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/20260630125055_InitialProjection.cs

@@ -0,0 +1,53 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Projection.ReadModel.Migrations
+{
+    /// <inheritdoc />
+    public partial class InitialProjection : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "processed_notifications",
+                columns: table => new
+                {
+                    key = table.Column<string>(type: "text", nullable: false),
+                    actie = table.Column<string>(type: "text", nullable: false),
+                    zaak_id = table.Column<string>(type: "text", nullable: false),
+                    received_at = table.Column<DateTimeOffset>(type: "timestamp with time zone", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_processed_notifications", x => x.key);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "register_projection",
+                columns: table => new
+                {
+                    id = table.Column<string>(type: "text", nullable: false),
+                    status = table.Column<string>(type: "text", nullable: false),
+                    bsn = table.Column<string>(type: "text", nullable: true),
+                    naam_placeholder = table.Column<string>(type: "text", nullable: true)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_register_projection", x => x.id);
+                });
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "processed_notifications");
+
+            migrationBuilder.DropTable(
+                name: "register_projection");
+        }
+    }
+}

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

@@ -0,0 +1,76 @@
+// <auto-generated />
+using System;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+using Projection.ReadModel;
+
+#nullable disable
+
+namespace Projection.ReadModel.Migrations
+{
+    [DbContext(typeof(ProjectionDbContext))]
+    partial class ProjectionDbContextModelSnapshot : ModelSnapshot
+    {
+        protected override void BuildModel(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>("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/Projection.ReadModel.csproj

@@ -0,0 +1,28 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <!-- Audit only the packages we choose directly. The one flagged transitive
+         (System.Security.Cryptography.Xml, NU1903) comes via EF Core's design-time
+         migration tooling (Microsoft.EntityFrameworkCore.Design, PrivateAssets=all) and
+         is never shipped at runtime — it is out of our control to upgrade. -->
+    <NuGetAuditMode>direct</NuGetAuditMode>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\event-subscriber\EventSubscriber.Application\EventSubscriber.Application.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="10.0.0" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Relational" Version="10.0.0" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="10.0.0">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="10.0.0" />
+  </ItemGroup>
+
+</Project>

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

@@ -0,0 +1,59 @@
+using Microsoft.EntityFrameworkCore;
+
+namespace Projection.ReadModel;
+
+/// <summary>
+/// The read projection's persistence. This single store is the system's rebuildable read model
+/// (PRD §8.4): the Event Subscriber writes to it (projector) and the projection-api reads it
+/// (query). Both processes are the one "Read Projection" bounded context and share this schema —
+/// not a cross-domain DB share (ADR-0008 reconciles this with CLAUDE.md §8.5).
+/// </summary>
+public sealed class ProjectionDbContext(DbContextOptions<ProjectionDbContext> options) : DbContext(options)
+{
+    /// <summary>The public-facing register rows (public-safe filtering is tightened in S-09).</summary>
+    public DbSet<RegisterEntryRow> RegisterEntries => Set<RegisterEntryRow>();
+
+    /// <summary>The Event Subscriber's durable log of accepted notifications — idempotency guard and rebuild source.</summary>
+    public DbSet<ProcessedNotificationRow> ProcessedNotifications => Set<ProcessedNotificationRow>();
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        modelBuilder.Entity<RegisterEntryRow>(e =>
+        {
+            e.ToTable("register_projection");
+            e.HasKey(r => r.Id);
+            e.Property(r => r.Id).HasColumnName("id");
+            e.Property(r => r.Status).HasColumnName("status").IsRequired();
+            e.Property(r => r.Bsn).HasColumnName("bsn");
+            e.Property(r => r.NaamPlaceholder).HasColumnName("naam_placeholder");
+        });
+
+        modelBuilder.Entity<ProcessedNotificationRow>(e =>
+        {
+            e.ToTable("processed_notifications");
+            e.HasKey(r => r.Key);
+            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.ReceivedAt).HasColumnName("received_at");
+        });
+    }
+}
+
+/// <summary>A register projection row. <c>Bsn</c>/<c>NaamPlaceholder</c> are deferred (ADR-0008).</summary>
+public sealed class RegisterEntryRow
+{
+    public required string Id { get; set; }
+    public required string Status { get; set; }
+    public string? Bsn { get; set; }
+    public string? NaamPlaceholder { get; set; }
+}
+
+/// <summary>An accepted notification, retained so the projection can be rebuilt without OpenZaak (§8.1).</summary>
+public sealed class ProcessedNotificationRow
+{
+    public required string Key { get; set; }
+    public required string Actie { get; set; }
+    public required string ZaakId { get; set; }
+    public DateTimeOffset ReceivedAt { get; set; }
+}

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

@@ -0,0 +1,30 @@
+using EventSubscriber.Application;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Projection.ReadModel;
+
+public static class ServiceCollectionExtensions
+{
+    /// <summary>Register the projection <see cref="ProjectionDbContext"/> against Postgres.</summary>
+    public static IServiceCollection AddProjectionReadModel(this IServiceCollection services, string connectionString)
+        => services.AddDbContext<ProjectionDbContext>(o => o.UseNpgsql(connectionString));
+
+    /// <summary>Register the write-side ports (projector store + notification log) used by the Event Subscriber.</summary>
+    public static IServiceCollection AddProjectionWriteSide(this IServiceCollection services)
+    {
+        services.AddScoped<IProjectionStore, EfProjectionStore>();
+        services.AddScoped<INotificationLog, EfNotificationLog>();
+        services.AddScoped<NotificationProjector>();
+        return services;
+    }
+
+    /// <summary>Apply any pending EF migrations. Called once on service start so a fresh stack
+    /// reaches a usable schema without a manual migration step (DoD: compose up reaches green).</summary>
+    public static async Task MigrateProjectionAsync(this IServiceProvider services, CancellationToken ct = default)
+    {
+        await using var scope = services.CreateAsyncScope();
+        var db = scope.ServiceProvider.GetRequiredService<ProjectionDbContext>();
+        await db.Database.MigrateAsync(ct);
+    }
+}

services/projection-api/ProjectionApi.Api/Program.cs

@@ -0,0 +1,43 @@
+using Microsoft.EntityFrameworkCore;
+using Projection.ReadModel;
+
+var builder = WebApplication.CreateBuilder(args);
+
+var connectionString = builder.Configuration.GetConnectionString("Projection")
+    ?? throw new InvalidOperationException("Missing connection string 'ConnectionStrings:Projection'");
+
+builder.Services.AddProjectionReadModel(connectionString);
+
+var app = builder.Build();
+
+// Ensure the schema exists before serving reads. EF serialises concurrent migrators via the
+// migrations-history lock, so it is safe that the Event Subscriber migrates too.
+await app.Services.MigrateProjectionAsync();
+
+app.MapGet("/health", () => "Healthy");
+
+// The read side of the projection. Public-safe field filtering is tightened in S-09; for now
+// the minimal projection only carries id + status (bsn/naam deferred — ADR-0008).
+app.MapGet("/register", async (ProjectionDbContext db, CancellationToken ct) =>
+{
+    var rows = await db.RegisterEntries
+        .OrderBy(r => r.Id)
+        .Select(r => new RegisterEntryDto(r.Id, r.Status, r.Bsn, r.NaamPlaceholder))
+        .ToListAsync(ct);
+    return Results.Ok(rows);
+});
+
+app.MapGet("/register/{id}", async (string id, ProjectionDbContext db, CancellationToken ct) =>
+{
+    var row = await db.RegisterEntries
+        .Where(r => r.Id == id)
+        .Select(r => new RegisterEntryDto(r.Id, r.Status, r.Bsn, r.NaamPlaceholder))
+        .SingleOrDefaultAsync(ct);
+    return row is null ? Results.NotFound() : Results.Ok(row);
+});
+
+await app.RunAsync();
+
+public sealed record RegisterEntryDto(string Id, string Status, string? Bsn, string? NaamPlaceholder);
+
+public partial class Program;

services/projection-api/ProjectionApi.Api/ProjectionApi.Api.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <ItemGroup>
+    <ProjectReference Include="..\Projection.ReadModel\Projection.ReadModel.csproj" />
+  </ItemGroup>
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+</Project>

services/projection-api/ProjectionApi.Api/appsettings.json

@@ -0,0 +1,8 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}