src/main/java/net/hostsharing/hsadminng/hs/hosting/asset/HsHostingAsset.java

@@ -34,6 +34,7 @@ import jakarta.persistence.OneToOne;
 import jakarta.persistence.PostLoad;
 import jakarta.persistence.Transient;
 import jakarta.persistence.Version;
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -115,6 +116,13 @@ public abstract class HsHostingAsset implements Stringifyable, BaseEntity<HsHost
         this.isLoaded = true;
     }
 
+    public List<HsHostingAssetRealEntity> getSubHostingAssets() {
+        if (subHostingAssets == null) {
+            subHostingAssets = new ArrayList<>();
+        }
+        return subHostingAssets;
+    }
+
     public PatchableMapWrapper<Object> getConfig() {
         return PatchableMapWrapper.of(configWrapper, (newWrapper) -> {configWrapper = newWrapper;}, config);
     }

src/main/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HostingAssetEntitySaveProcessor.java

@@ -66,6 +66,8 @@ public class HostingAssetEntitySaveProcessor {
     public HostingAssetEntitySaveProcessor saveUsing(final Function<HsHostingAsset, HsHostingAsset> saveFunction) {
         step("saveUsing", "validateContext");
         entity = saveFunction.apply(entity);
+        em.flush(); // makes RbacEntity available as RealEntity if needed
+        validator.postPersist(em, entity);
         return this;
     }
 

src/main/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsManagedWebspaceHostingAssetValidator.java

@@ -1,10 +1,13 @@
 package net.hostsharing.hsadminng.hs.hosting.asset.validators;
 
 import net.hostsharing.hsadminng.hs.hosting.asset.HsHostingAsset;
+import net.hostsharing.hsadminng.hs.hosting.asset.HsHostingAssetRealEntity;
 
+import jakarta.persistence.EntityManager;
 import java.util.regex.Pattern;
 
 import static net.hostsharing.hsadminng.hs.hosting.asset.HsHostingAssetType.MANAGED_WEBSPACE;
+import static net.hostsharing.hsadminng.hs.hosting.asset.HsHostingAssetType.UNIX_USER;
 
 class HsManagedWebspaceHostingAssetValidator extends HostingAssetEntityValidator {
     public HsManagedWebspaceHostingAssetValidator() {
@@ -22,4 +25,32 @@ class HsManagedWebspaceHostingAssetValidator extends HostingAssetEntityValidator
                         : "[a-z][a-z0-9][a-z0-9]";
         return Pattern.compile("^" + prefixPattern + "[0-9][0-9]$");
     }
+
+    @Override
+    public void postPersist(final EntityManager em, final HsHostingAsset webspaceAsset) {
+        if (!webspaceAsset.isLoaded()) {
+            final var unixUserAsset = HsHostingAssetRealEntity.builder()
+                    .type(UNIX_USER)
+                    .parentAsset(em.find(HsHostingAssetRealEntity.class, webspaceAsset.getUuid()))
+                    .identifier(webspaceAsset.getIdentifier())
+                    .caption(webspaceAsset.getIdentifier() + " webspace user")
+                    .build();
+            webspaceAsset.getSubHostingAssets().add(unixUserAsset);
+            final var emw = new EntityManagerWrapper(em);
+            new HostingAssetEntitySaveProcessor(em, unixUserAsset)
+                    .preprocessEntity()
+                    .validateEntity()
+                    .prepareForSave()
+                    .saveUsing(emw::persist)
+                    .validateContext();
+        }
+    }
+}
+
+record EntityManagerWrapper(EntityManager em) {
+
+    HsHostingAsset persist(HsHostingAsset hsHostingAsset) {
+        em.persist(hsHostingAsset);
+        return hsHostingAsset;
+    }
 }

src/main/java/net/hostsharing/hsadminng/hs/validation/HsEntityValidator.java

@@ -160,4 +160,7 @@ public abstract class HsEntityValidator<E extends PropertiesProvider> {
     public ValidatableProperty<?, ?> getProperty(final String propertyName) {
         return stream(propertyValidators).filter(pv -> pv.propertyName().equals(propertyName)).findFirst().orElse(null);
     }
+
+    public void postPersist(final EntityManager em, final E entity) {
+    }
 }

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/HsHostingAssetControllerAcceptanceTest.java

@@ -182,11 +182,23 @@ class HsHostingAssetControllerAcceptanceTest extends ContextBasedTestWithCleanup
                         .header("Location", matchesRegex("http://localhost:[1-9][0-9]*/api/hs/hosting/assets/[^/]*"))
                     .extract().header("Location");  // @formatter:on
 
-            // finally, the new asset can be accessed under the generated UUID
-            final var newWebspace = UUID.fromString(
+            // the new asset can be accessed under the generated UUID
+            final var newWebspaceUuid = UUID.fromString(
                     location.substring(location.lastIndexOf('/') + 1));
-            assertThat(newWebspace).isNotNull();
-            toCleanup(HsHostingAssetRbacEntity.class, newWebspace);
+            assertThat(newWebspaceUuid).isNotNull();
+            toCleanup(HsHostingAssetRbacEntity.class, newWebspaceUuid);
+
+            // and a default user got created
+            final var webspaceUnixUser = em.createQuery("SELECT ha FROM HsHostingAssetRealEntity ha WHERE ha.parentAsset.uuid=:webspaceUUID")
+                    .setParameter("webspaceUUID", newWebspaceUuid)
+                    .getSingleResult();
+            assertThat(webspaceUnixUser).isNotNull().extracting(Object::toString)
+                    .isEqualTo("""
+                            HsHostingAsset(UNIX_USER, fir10, fir10 webspace user, MANAGED_WEBSPACE:fir10, {
+                              "password" : null,
+                              "userid" : 1000000
+                            })
+                            """.trim());
         }
 
         @Test
@@ -325,7 +337,7 @@ class HsHostingAssetControllerAcceptanceTest extends ContextBasedTestWithCleanup
 
             jpaAttempt.transacted(() -> {
                 context.define("superuser-alex@hostsharing.net");
-                for (int n = 0; n < UNIX_USER_PER_MULTI_OPTION -preExistingUnixUserCount+1; ++n) {
+                for (int n = 0; n < UNIX_USER_PER_MULTI_OPTION-preExistingUnixUserCount; ++n) {
                     toCleanup(realAssetRepo.save(
                             HsHostingAssetRealEntity.builder()
                                     .type(UNIX_USER)