services/acl/Acl.Infrastructure/ObjectenGateway.cs

@@ -41,7 +41,7 @@ public sealed class ObjectenGateway(HttpClient http, ObjectenOptions options, IC
     private RecordDto NewRecord(int typeVersion, RecordDataDto data) =>
         new(typeVersion, data, clock.Today.ToString("yyyy-MM-dd"));
 
-    /// <summary>The URL + latest version number of the configured objecttype, read from Objecttypen.</summary>
+    /// <summary>The URL + latest published version of the configured objecttype, read from Objecttypen.</summary>
     private async Task<Objecttype> ResolveObjecttypeAsync(CancellationToken ct)
     {
         var page = await GetAsync<ObjecttypePage>(
@@ -52,10 +52,16 @@ public sealed class ObjectenGateway(HttpClient http, ObjectenOptions options, IC
             ?? throw new InvalidOperationException(
                 $"No objecttype '{options.ObjecttypeName}' registered in Objecttypen — is the RegisterRecord seed applied?");
 
-        // `versions` lists the objecttype's version URLs; the count is the latest version number.
-        var version = match.Versions?.Count
-            ?? throw new InvalidOperationException($"Objecttype '{options.ObjecttypeName}' has no published version");
-        return new Objecttype(new Uri(match.Url), version);
+        var url = new Uri(match.Url);
+        // Write against the highest *published* version: a draft version's schema is still being
+        // shaped, and objects written against it would be validated by a moving target.
+        var versions = await GetAsync<IReadOnlyList<ObjecttypeVersionDto>>(
+            new Uri(url + "/versions"), options.ObjecttypenToken, crs: false, "objecttype versions", ct);
+        var latest = versions.Where(v => v.Status == "published").Select(v => v.Version).DefaultIfEmpty(0).Max();
+        if (latest == 0)
+            throw new InvalidOperationException($"Objecttype '{options.ObjecttypeName}' has no published version");
+
+        return new Objecttype(url, latest);
     }
 
     /// <summary>The URL of the object already holding this registration's record, or null if there is none.</summary>
@@ -115,8 +121,11 @@ public sealed class ObjectenGateway(HttpClient http, ObjectenOptions options, IC
 
     private sealed record ObjecttypeDto(
         [property: JsonPropertyName("url")] string Url,
-        [property: JsonPropertyName("name")] string? Name,
-        [property: JsonPropertyName("versions")] IReadOnlyList<string>? Versions);
+        [property: JsonPropertyName("name")] string? Name);
+
+    private sealed record ObjecttypeVersionDto(
+        [property: JsonPropertyName("version")] int Version,
+        [property: JsonPropertyName("status")] string? Status);
 
     private sealed record ObjectPage(
         [property: JsonPropertyName("results")] IReadOnlyList<ObjectDto>? Results);

services/acl/Acl.Tests/ObjectenGatewayTests.cs

@@ -46,24 +46,32 @@ public class ObjectenGatewayTests
             },
             new FixedClock(new DateOnly(2026, 6, 4)));
 
-    // The Objecttypen lookup (by name) and the Objecten search (by data attribute) that precede every
-    // write. `respondToWrite` decides what the POST/PATCH returns.
+    // A stack that answers the three reads every write is preceded by: the objecttype list (matched by
+    // name), that objecttype's versions, and the Objecten search for an existing record.
     private static HttpResponseMessage Route(HttpRequestMessage req, object[] existingObjects) =>
-        req.RequestUri!.AbsolutePath.StartsWith("/api/v2/objecttypes", StringComparison.Ordinal)
-            ? new HttpResponseMessage(HttpStatusCode.OK)
+        req.RequestUri!.AbsolutePath.EndsWith("/versions", StringComparison.Ordinal)
+            ? Json(new object[]
             {
-                Content = JsonContent.Create(new
+                new { version = 1, status = "published" },
+                new { version = 2, status = "published" },
+                // A draft must never be written against, even though it is the highest version.
+                new { version = 3, status = "draft" },
+            })
+            : req.RequestUri.AbsolutePath.StartsWith("/api/v2/objecttypes", StringComparison.Ordinal)
+                ? Json(new
                 {
                     results = new[]
                     {
-                        new { url = "http://objecttypen:8000/api/v2/objecttypes/other", name = "SomethingElse", versions = new[] { "…/versions/1" } },
-                        new { url = ObjecttypeUrl, name = "RegisterRecord", versions = new[] { "…/versions/1", "…/versions/2" } },
+                        new { url = "http://objecttypen:8000/api/v2/objecttypes/other", name = "SomethingElse" },
+                        new { url = ObjecttypeUrl, name = "RegisterRecord" },
                     },
-                }),
-            }
-            : req.Method == HttpMethod.Get
-                ? new HttpResponseMessage(HttpStatusCode.OK) { Content = JsonContent.Create(new { results = existingObjects }) }
-                : new HttpResponseMessage(HttpStatusCode.Created) { Content = JsonContent.Create(new { url = "http://objecten:8000/api/v2/objects/obj-1" }) };
+                })
+                : req.Method == HttpMethod.Get
+                    ? Json(new { results = existingObjects })
+                    : new HttpResponseMessage(HttpStatusCode.Created) { Content = JsonContent.Create(new { url = "http://objecten:8000/api/v2/objects/obj-1" }) };
+
+    private static HttpResponseMessage Json(object body) =>
+        new(HttpStatusCode.OK) { Content = JsonContent.Create(body) };
 
     private static RegisterRecord Record() => new("zaak-uuid-1", RegisterRecordStatus.Ingeschreven, "REG-2026-0001");
 
@@ -76,6 +84,7 @@ public class ObjectenGatewayTests
 
         var write = sent.Single(s => s.Method == HttpMethod.Post && s.Uri.AbsolutePath == "/api/v2/objects");
         Assert.Contains($"\"type\":\"{ObjecttypeUrl}\"", write.Body);
+        // The highest *published* version (2), not the highest version (a draft 3).
         Assert.Contains("\"typeVersion\":2", write.Body);
         Assert.Contains("\"id\":\"zaak-uuid-1\"", write.Body);
         Assert.Contains("\"status\":\"INGESCHREVEN\"", write.Body);
@@ -145,7 +154,19 @@ public class ObjectenGatewayTests
         await gateway.UpsertAsync(Record());
         await gateway.UpsertAsync(Record() with { Id = "zaak-uuid-2" });
 
-        Assert.Single(sent, s => s.Uri.AbsolutePath.StartsWith("/api/v2/objecttypes", StringComparison.Ordinal));
+        Assert.Single(sent, s => s.Uri.AbsolutePath == "/api/v2/objecttypes");
+    }
+
+    [Fact]
+    public async Task Fails_loudly_when_the_objecttype_has_no_published_version()
+    {
+        var sent = new List<Sent>();
+        var gateway = Gateway(sent, req => req.RequestUri!.AbsolutePath.EndsWith("/versions", StringComparison.Ordinal)
+            ? Json(new object[] { new { version = 1, status = "draft" } })
+            : Route(req, []));
+
+        var error = await Assert.ThrowsAsync<InvalidOperationException>(() => gateway.UpsertAsync(Record()));
+        Assert.Contains("published version", error.Message);
     }
 
     [Fact]