feat(openzaak): per-document-type confidentialiteit config (WP-59)

Drives the DRC upload's vertrouwelijkheidaanduiding from a new stamdata
table instead of the hardcoded "openbaar", following the existing
config-as-code pattern (ADR-0004). Adds the referential-integrity check
StamdataValidationTests was missing for the new table.

backend/src/BigRegister.Api/Stamdata/DocumentConfidentialiteit.cs

@@ -0,0 +1,12 @@
+namespace BigRegister.Stamdata;
+
+/// <summary>
+/// One row of the document-confidentialiteit stamdata (config-as-code, ADR-0004): the ZGW
+/// <c>vertrouwelijkheidaanduiding</c> to register a DRC document with, per upload category
+/// (<see cref="BigRegister.Domain.Documents.DocumentCategory.CategoryId"/>). The first
+/// property (<see cref="CategoryId"/>) is the table key by convention (see
+/// <c>StamdataTable</c>). Non-temporal — a category's sensitivity doesn't change over time.
+/// A category absent from this table falls back to <c>"openbaar"</c> (see
+/// <c>OpenZaakDocumentSource</c>) rather than failing the upload.
+/// </summary>
+public sealed record DocumentConfidentialiteit(string CategoryId, string Vertrouwelijkheidaanduiding);

backend/src/BigRegister.Api/Stamdata/StamdataCatalog.cs

@@ -14,6 +14,7 @@ public static class StamdataCatalog
     StamdataTable.Of<Beroep>("beroepen", "Beroepen (BIG)"),
     StamdataTable.Of<Opleiding>("opleidingen", "Opleidingen → beroep"),
     StamdataTable.Of<Specialisme>("specialismen", "Specialismen → beroep"),
+    StamdataTable.Of<DocumentConfidentialiteit>("documentconfidentialiteit", "Documenttype → vertrouwelijkheidaanduiding"),
     // PolicyQuestions and future tables migrate here, same one-liner each.
   };
 

backend/src/BigRegister.Api/Stamdata/documentconfidentialiteit.json

@@ -0,0 +1,7 @@
+[
+  { "categoryId": "identiteit", "vertrouwelijkheidaanduiding": "vertrouwelijk" },
+  { "categoryId": "diploma", "vertrouwelijkheidaanduiding": "openbaar" },
+  { "categoryId": "taalvaardigheid", "vertrouwelijkheidaanduiding": "openbaar" },
+  { "categoryId": "werkervaring", "vertrouwelijkheidaanduiding": "openbaar" },
+  { "categoryId": "nascholing", "vertrouwelijkheidaanduiding": "openbaar" }
+]

backend/src/BigRegister.Api/Zgw/OpenZaakDocumentSource.cs

@@ -3,6 +3,7 @@ using System.Text.Json.Serialization;
 using BigRegister.Api.Contracts;
 using BigRegister.Api.Data;
 using BigRegister.Domain.Authorization;
+using BigRegister.Stamdata;
 
 namespace BigRegister.Api.Zgw;
 
@@ -23,6 +24,15 @@ public sealed class OpenZaakDocumentSource(HttpClient http, ZgwTokenProvider tok
 {
   private readonly ZgwHttpClient zgw = new(http, tokens);
 
+  // WP-59: per-document-type confidentiality (stamdata, ADR-0004) — "openbaar" if the
+  // category isn't in the table, so an unconfigured category never fails the upload.
+  private static readonly IReadOnlyDictionary<string, string> ConfidentialiteitByCategory =
+      StamdataFile.Load<DocumentConfidentialiteit>("documentconfidentialiteit")
+          .ToDictionary(r => r.CategoryId, r => r.Vertrouwelijkheidaanduiding);
+
+  private static string ConfidentialiteitFor(string categoryId) =>
+      ConfidentialiteitByCategory.GetValueOrDefault(categoryId, "openbaar");
+
   // ponytail: sync-over-async — IDocumentSource is sync to match the local store + the
   // existing sync upload/submit endpoints, same reasoning as OpenZaakZaakSource.
   public UploadResponse Upload(
@@ -52,10 +62,7 @@ public sealed class OpenZaakDocumentSource(HttpClient http, ZgwTokenProvider tok
         Inhoud: Convert.ToBase64String(content),
         Informatieobjecttype: informatieobjecttypeUrl,
         Identificatie: doc.DocumentId,
-        // ponytail: hardcoded "openbaar" (public) — real usage would likely vary the
-        // confidentiality level per category (e.g. an identity document is more sensitive
-        // than a diploma); a fixed value is enough to prove the seam end-to-end.
-        Vertrouwelijkheidaanduiding: "openbaar"), caller);
+        Vertrouwelijkheidaanduiding: ConfidentialiteitFor(categoryId)), caller);
 
     DocumentStore.SetDrcUrl(doc.DocumentId, eio.Url);
     return new UploadResponse(doc.DocumentId, doc.LocalId);

backend/tests/BigRegister.Tests/OpenZaakDocumentSourceTests.cs

@@ -58,6 +58,23 @@ public class OpenZaakDocumentSourceTests
     Assert.Contains("123443210", body);       // bronorganisatie
     Assert.Contains("paspoort.pdf", body);
     Assert.Contains(Convert.ToBase64String("%PDF-1.4 fake"u8.ToArray()), body); // inhoud
+    // WP-59: "identiteit" is mapped to "vertrouwelijk" in the confidentialiteit stamdata.
+    Assert.Contains("\"vertrouwelijkheidaanduiding\":\"vertrouwelijk\"", body);
+  }
+
+  [Fact]
+  public void Upload_falls_back_to_openbaar_for_a_category_absent_from_the_confidentialiteit_table()
+  {
+    var options = Options();
+    options.InformatieobjecttypeUrls["org-logo"] = InformatieobjecttypeUrl;
+    var handler = new ZgwStubHandler(url =>
+        """{ "url": "https://oz.example/documenten/api/v1/enkelvoudiginformatieobjecten/eio-2" }""");
+    var source = new OpenZaakDocumentSource(new HttpClient(handler), new ZgwTokenProvider(options), options);
+
+    source.Upload("local-2", "org-logo", "org-template", "logo.png", "image/png", [1, 2, 3], Caller);
+
+    var body = handler.BodyOf($"{DrcBase}/enkelvoudiginformatieobjecten");
+    Assert.Contains("\"vertrouwelijkheidaanduiding\":\"openbaar\"", body);
   }
 
   [Fact]

backend/tests/BigRegister.Tests/StamdataValidationTests.cs

@@ -1,5 +1,6 @@
 using BigRegister.Api.Data;
 using BigRegister.Domain.Diplomas;
+using BigRegister.Domain.Documents;
 using BigRegister.Stamdata;
 
 namespace BigRegister.Tests;
@@ -22,6 +23,14 @@ public class StamdataValidationTests
   private static readonly IReadOnlySet<string> BeroepCodes =
       StamdataFile.Load<Beroep>("beroepen").Select(b => b.Code).ToHashSet(StringComparer.Ordinal);
 
+  // Every document category id that exists across any wizard (WP-59's confidentialiteit
+  // table points at these) — "org-logo" resolves too, even though it's deliberately absent
+  // from the confidentialiteit table itself (falls back to "openbaar").
+  private static readonly IReadOnlySet<string> DocumentCategoryIds = new[] { "registratie", "herregistratie", "org-template" }
+      .SelectMany(DocumentRules.AllCategoriesFor)
+      .Select(c => c.CategoryId)
+      .ToHashSet(StringComparer.Ordinal);
+
   private static readonly IReadOnlyList<StamdataRef> References = new[]
   {
     new StamdataRef(
@@ -38,6 +47,12 @@ public class StamdataValidationTests
         "Specialisme.beroep → beroepen.code",
         StamdataFile.Load<Specialisme>("specialismen").Select(s => s.Beroep),
         key => BeroepCodes.Contains(key)),
+    // WP-59: a confidentialiteit row for a category that no wizard ever asks for is dead
+    // config — fail the build rather than let it silently rot.
+    new StamdataRef(
+        "DocumentConfidentialiteit.CategoryId → a real document category",
+        StamdataFile.Load<DocumentConfidentialiteit>("documentconfidentialiteit").Select(d => d.CategoryId),
+        key => DocumentCategoryIds.Contains(key)),
   };
 
   [Fact]