fix(production): JPA-Save-Pattern, Optimistic Locking und Domain-Validierung

- Managed-Entity-Update statt detach/merge (verhindert DELETE+INSERT-Churn)
- @Version für Optimistic Locking mit ConcurrentModification-Error
- Null-Checks für quantityUsed/quantityUnit vor BigDecimal-Parsing
- Duplicate-Check nach Consumption.create() für robustere Validierung
- FetchType.EAGER→LAZY für BatchEntity.consumptions
- Liquibase-Migration 020 für version-Spalte

backend/src/main/java/de/effigenix/domain/production/Batch.java

@@ -37,6 +37,7 @@ public class Batch {
     private final LocalDate bestBeforeDate;
     private final OffsetDateTime createdAt;
     private OffsetDateTime updatedAt;
+    private final long version;
     private final List<Consumption> consumptions;
 
     private Batch(
@@ -49,6 +50,7 @@ public class Batch {
             LocalDate bestBeforeDate,
             OffsetDateTime createdAt,
             OffsetDateTime updatedAt,
+            long version,
             List<Consumption> consumptions
     ) {
         this.id = id;
@@ -60,6 +62,7 @@ public class Batch {
         this.bestBeforeDate = bestBeforeDate;
         this.createdAt = createdAt;
         this.updatedAt = updatedAt;
+        this.version = version;
         this.consumptions = consumptions;
     }
 
@@ -110,6 +113,7 @@ public class Batch {
                 draft.bestBeforeDate(),
                 now,
                 now,
+                0L,
                 new ArrayList<>()
         ));
     }
@@ -128,21 +132,18 @@ public class Batch {
             return Result.failure(new BatchError.NotInProduction(id));
         }
 
-        if (draft.inputBatchId() != null && !draft.inputBatchId().isBlank()) {
-            var inputId = BatchId.of(draft.inputBatchId());
-            boolean duplicate = consumptions.stream()
-                    .anyMatch(c -> c.inputBatchId().equals(inputId));
-            if (duplicate) {
-                return Result.failure(new BatchError.DuplicateInputBatch(inputId));
-            }
-        }
-
         Consumption consumption;
         switch (Consumption.create(draft)) {
             case Result.Failure(var err) -> { return Result.failure(err); }
             case Result.Success(var val) -> consumption = val;
         }
 
+        boolean duplicate = consumptions.stream()
+                .anyMatch(c -> c.inputBatchId().equals(consumption.inputBatchId()));
+        if (duplicate) {
+            return Result.failure(new BatchError.DuplicateInputBatch(consumption.inputBatchId()));
+        }
+
         consumptions.add(consumption);
         this.updatedAt = OffsetDateTime.now(ZoneOffset.UTC);
         return Result.success(consumption);
@@ -158,10 +159,11 @@ public class Batch {
             LocalDate bestBeforeDate,
             OffsetDateTime createdAt,
             OffsetDateTime updatedAt,
+            long version,
             List<Consumption> consumptions
     ) {
         return new Batch(id, batchNumber, recipeId, status, plannedQuantity, productionDate,
-                bestBeforeDate, createdAt, updatedAt, new ArrayList<>(consumptions));
+                bestBeforeDate, createdAt, updatedAt, version, new ArrayList<>(consumptions));
     }
 
     public BatchId id() { return id; }
@@ -173,5 +175,6 @@ public class Batch {
     public LocalDate bestBeforeDate() { return bestBeforeDate; }
     public OffsetDateTime createdAt() { return createdAt; }
     public OffsetDateTime updatedAt() { return updatedAt; }
+    public long version() { return version; }
     public List<Consumption> consumptions() { return Collections.unmodifiableList(consumptions); }
 }

backend/src/main/java/de/effigenix/domain/production/Consumption.java

@@ -34,6 +34,13 @@ public class Consumption {
             return Result.failure(new BatchError.ValidationFailure("articleId must not be blank"));
         }
 
+        if (draft.quantityUsed() == null || draft.quantityUsed().isBlank()) {
+            return Result.failure(new BatchError.InvalidConsumptionQuantity("quantityUsed must not be blank"));
+        }
+        if (draft.quantityUnit() == null || draft.quantityUnit().isBlank()) {
+            return Result.failure(new BatchError.InvalidConsumptionQuantity("quantityUnit must not be blank"));
+        }
+
         Quantity quantity;
         try {
             var amount = new BigDecimal(draft.quantityUsed());

backend/src/main/java/de/effigenix/domain/production/event/BatchStarted.java

@@ -4,4 +4,8 @@ import de.effigenix.domain.production.BatchId;
 
 import java.time.OffsetDateTime;
 
+/**
+ * Stub – wird derzeit nicht publiziert.
+ * Vorgesehen für spätere Event-Infrastruktur (Audit, Inventory-Deduction, Tracing).
+ */
 public record BatchStarted(BatchId batchId, OffsetDateTime startedAt) {}

backend/src/main/java/de/effigenix/domain/production/event/ConsumptionRecorded.java

@@ -3,4 +3,8 @@ package de.effigenix.domain.production.event;
 import de.effigenix.domain.production.BatchId;
 import de.effigenix.domain.production.ConsumptionId;
 
+/**
+ * Stub – wird derzeit nicht publiziert.
+ * Vorgesehen für spätere Event-Infrastruktur (Chargen-Genealogie, Bestandsabzug).
+ */
 public record ConsumptionRecorded(BatchId batchId, ConsumptionId consumptionId, BatchId inputBatchId) {}

backend/src/main/java/de/effigenix/infrastructure/production/persistence/entity/BatchEntity.java

@@ -16,6 +16,10 @@ public class BatchEntity {
     @Column(name = "id", nullable = false, length = 36)
     private String id;
 
+    @Version
+    @Column(name = "version", nullable = false)
+    private Long version;
+
     @Column(name = "batch_number", nullable = false, unique = true, length = 20)
     private String batchNumber;
 
@@ -43,7 +47,7 @@ public class BatchEntity {
     @Column(name = "updated_at", nullable = false)
     private OffsetDateTime updatedAt;
 
-    @OneToMany(mappedBy = "batch", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.EAGER)
+    @OneToMany(mappedBy = "batch", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.LAZY)
     private List<ConsumptionEntity> consumptions = new ArrayList<>();
 
     protected BatchEntity() {}
@@ -73,6 +77,7 @@ public class BatchEntity {
     }
 
     public String getId() { return id; }
+    public Long getVersion() { return version; }
     public String getBatchNumber() { return batchNumber; }
     public String getRecipeId() { return recipeId; }
     public String getStatus() { return status; }
@@ -83,5 +88,7 @@ public class BatchEntity {
     public OffsetDateTime getCreatedAt() { return createdAt; }
     public OffsetDateTime getUpdatedAt() { return updatedAt; }
     public List<ConsumptionEntity> getConsumptions() { return consumptions; }
-    public void setConsumptions(List<ConsumptionEntity> consumptions) { this.consumptions = consumptions; }
+
+    public void setStatus(String status) { this.status = status; }
+    public void setUpdatedAt(OffsetDateTime updatedAt) { this.updatedAt = updatedAt; }
 }

backend/src/main/java/de/effigenix/infrastructure/production/persistence/mapper/BatchMapper.java

@@ -8,8 +8,9 @@ import de.effigenix.shared.common.Quantity;
 import de.effigenix.shared.common.UnitOfMeasure;
 import org.springframework.stereotype.Component;
 
-import java.util.ArrayList;
 import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
 
 @Component
 public class BatchMapper {
@@ -28,23 +29,28 @@ public class BatchMapper {
                 batch.updatedAt()
         );
 
-        List<ConsumptionEntity> consumptionEntities = new ArrayList<>();
         for (Consumption c : batch.consumptions()) {
-            consumptionEntities.add(new ConsumptionEntity(
+            entity.getConsumptions().add(toConsumptionEntity(c, entity));
-                    c.id().value(),
-                    entity,
-                    c.inputBatchId().value(),
-                    c.articleId().value(),
-                    c.quantityUsed().amount(),
-                    c.quantityUsed().uom().name(),
-                    c.consumedAt()
-            ));
         }
-        entity.setConsumptions(consumptionEntities);
 
         return entity;
     }
 
+    public void updateEntity(BatchEntity entity, Batch batch) {
+        entity.setStatus(batch.status().name());
+        entity.setUpdatedAt(batch.updatedAt());
+
+        Set<String> existingIds = entity.getConsumptions().stream()
+                .map(ConsumptionEntity::getId)
+                .collect(Collectors.toSet());
+
+        for (Consumption c : batch.consumptions()) {
+            if (!existingIds.contains(c.id().value())) {
+                entity.getConsumptions().add(toConsumptionEntity(c, entity));
+            }
+        }
+    }
+
     public Batch toDomain(BatchEntity entity) {
         List<Consumption> consumptions = entity.getConsumptions().stream()
                 .map(ce -> Consumption.reconstitute(
@@ -72,7 +78,20 @@ public class BatchMapper {
                 entity.getBestBeforeDate(),
                 entity.getCreatedAt(),
                 entity.getUpdatedAt(),
+                entity.getVersion(),
                 consumptions
         );
     }
+
+    private ConsumptionEntity toConsumptionEntity(Consumption c, BatchEntity parent) {
+        return new ConsumptionEntity(
+                c.id().value(),
+                parent,
+                c.inputBatchId().value(),
+                c.articleId().value(),
+                c.quantityUsed().amount(),
+                c.quantityUsed().uom().name(),
+                c.consumedAt()
+        );
+    }
 }

backend/src/main/java/de/effigenix/infrastructure/production/persistence/repository/JpaBatchRepository.java

@@ -7,6 +7,7 @@ import de.effigenix.shared.common.Result;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.context.annotation.Profile;
+import org.springframework.orm.ObjectOptimisticLockingFailureException;
 import org.springframework.stereotype.Repository;
 import org.springframework.transaction.annotation.Transactional;
 
@@ -111,8 +112,17 @@ public class JpaBatchRepository implements BatchRepository {
     @Transactional
     public Result<RepositoryError, Void> save(Batch batch) {
         try {
+            var existing = jpaRepository.findById(batch.id().value());
+            if (existing.isPresent()) {
+                mapper.updateEntity(existing.get(), batch);
+            } else {
                 jpaRepository.save(mapper.toEntity(batch));
+            }
             return Result.success(null);
+        } catch (ObjectOptimisticLockingFailureException e) {
+            logger.warn("Optimistic locking failure for batch {}", batch.id().value());
+            return Result.failure(new RepositoryError.ConcurrentModification(
+                    "Batch was modified by another transaction"));
         } catch (Exception e) {
             logger.trace("Database error in save", e);
             return Result.failure(new RepositoryError.DatabaseError(e.getMessage()));

backend/src/main/java/de/effigenix/shared/common/RepositoryError.java

@@ -21,4 +21,7 @@ public sealed interface RepositoryError {
 
     record DatabaseError(String message) implements RepositoryError {
     }
+
+    record ConcurrentModification(String message) implements RepositoryError {
+    }
 }

backend/src/main/resources/db/changelog/changes/020-add-version-to-batches.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<databaseChangeLog
+        xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
+        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
+        http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-latest.xsd">
+
+    <changeSet id="020-add-version-to-batches" author="effigenix">
+        <addColumn tableName="batches">
+            <column name="version" type="bigint" defaultValueNumeric="0">
+                <constraints nullable="false"/>
+            </column>
+        </addColumn>
+    </changeSet>
+
+</databaseChangeLog>

backend/src/main/resources/db/changelog/db.changelog-master.xml

@@ -24,5 +24,6 @@
     <include file="db/changelog/changes/017-timestamps-to-timestamptz.xml"/>
     <include file="db/changelog/changes/018-add-article-id-to-recipes.xml"/>
     <include file="db/changelog/changes/019-create-batch-consumptions-table.xml"/>
+    <include file="db/changelog/changes/020-add-version-to-batches.xml"/>
 
 </databaseChangeLog>

backend/src/test/java/de/effigenix/application/production/FindBatchByNumberTest.java

@@ -53,7 +53,7 @@ class FindBatchByNumberTest {
                 LocalDate.of(2026, 6, 1),
                 OffsetDateTime.now(ZoneOffset.UTC),
                 OffsetDateTime.now(ZoneOffset.UTC),
-                List.of()
+                0L, List.of()
         );
     }
 

backend/src/test/java/de/effigenix/application/production/GetBatchTest.java

@@ -51,7 +51,7 @@ class GetBatchTest {
                 LocalDate.of(2026, 6, 1),
                 OffsetDateTime.now(ZoneOffset.UTC),
                 OffsetDateTime.now(ZoneOffset.UTC),
-                List.of()
+                0L, List.of()
         );
     }
 

backend/src/test/java/de/effigenix/application/production/ListBatchesTest.java

@@ -55,7 +55,7 @@ class ListBatchesTest {
                 LocalDate.of(2026, 6, 1),
                 OffsetDateTime.now(ZoneOffset.UTC),
                 OffsetDateTime.now(ZoneOffset.UTC),
-                List.of()
+                0L, List.of()
         );
     }
 

backend/src/test/java/de/effigenix/application/production/RecordConsumptionTest.java

@@ -52,7 +52,7 @@ class RecordConsumptionTest {
                 LocalDate.of(2026, 6, 1),
                 OffsetDateTime.now(ZoneOffset.UTC),
                 OffsetDateTime.now(ZoneOffset.UTC),
-                List.of()
+                0L, List.of()
         );
     }
 
@@ -67,7 +67,7 @@ class RecordConsumptionTest {
                 LocalDate.of(2026, 6, 1),
                 OffsetDateTime.now(ZoneOffset.UTC),
                 OffsetDateTime.now(ZoneOffset.UTC),
-                List.of()
+                0L, List.of()
         );
     }
 

backend/src/test/java/de/effigenix/application/production/StartBatchTest.java

@@ -52,7 +52,7 @@ class StartBatchTest {
                 LocalDate.of(2026, 6, 1),
                 OffsetDateTime.now(ZoneOffset.UTC),
                 OffsetDateTime.now(ZoneOffset.UTC),
-                List.of()
+                0L, List.of()
         );
     }
 
@@ -67,7 +67,7 @@ class StartBatchTest {
                 LocalDate.of(2026, 6, 1),
                 OffsetDateTime.now(ZoneOffset.UTC),
                 OffsetDateTime.now(ZoneOffset.UTC),
-                List.of()
+                0L, List.of()
         );
     }
 

backend/src/test/java/de/effigenix/domain/production/BatchTest.java

@@ -210,7 +210,7 @@ class BatchTest {
                     Quantity.of(new BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                     PRODUCTION_DATE, BEST_BEFORE_DATE,
                     OffsetDateTime.now(ZoneOffset.UTC), OffsetDateTime.now(ZoneOffset.UTC),
-                    List.of()
+                    0L, List.of()
             );
 
             var result = batch.startProduction();
@@ -231,7 +231,7 @@ class BatchTest {
                     Quantity.of(new BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                     PRODUCTION_DATE, BEST_BEFORE_DATE,
                     OffsetDateTime.now(ZoneOffset.UTC), OffsetDateTime.now(ZoneOffset.UTC),
-                    List.of()
+                    0L, List.of()
             );
 
             var result = batch.startProduction();
@@ -249,7 +249,7 @@ class BatchTest {
                     Quantity.of(new BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                     PRODUCTION_DATE, BEST_BEFORE_DATE,
                     OffsetDateTime.now(ZoneOffset.UTC), OffsetDateTime.now(ZoneOffset.UTC),
-                    List.of()
+                    0L, List.of()
             );
 
             var result = batch.startProduction();
@@ -313,7 +313,7 @@ class BatchTest {
                     Quantity.of(new BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                     PRODUCTION_DATE, BEST_BEFORE_DATE,
                     OffsetDateTime.now(ZoneOffset.UTC), OffsetDateTime.now(ZoneOffset.UTC),
-                    List.of()
+                    0L, List.of()
             );
             var draft = new ConsumptionDraft("input-1", "article-1", "5.0", "KILOGRAM");
 
@@ -379,7 +379,7 @@ class BatchTest {
                     BEST_BEFORE_DATE,
                     OffsetDateTime.now(ZoneOffset.UTC),
                     OffsetDateTime.now(ZoneOffset.UTC),
-                    List.of()
+                    0L, List.of()
             );
 
             assertThat(batch.id().value()).isEqualTo("batch-1");

backend/src/test/java/de/effigenix/domain/production/ConsumptionTest.java

@@ -111,6 +111,28 @@ class ConsumptionTest {
             assertThat(result.unsafeGetError()).isInstanceOf(BatchError.InvalidConsumptionQuantity.class);
         }
 
+        @Test
+        @DisplayName("should fail when quantity is null")
+        void should_Fail_When_QuantityNull() {
+            var draft = new ConsumptionDraft("input-batch-1", "article-1", null, "KILOGRAM");
+
+            var result = Consumption.create(draft);
+
+            assertThat(result.isFailure()).isTrue();
+            assertThat(result.unsafeGetError()).isInstanceOf(BatchError.InvalidConsumptionQuantity.class);
+        }
+
+        @Test
+        @DisplayName("should fail when unit is null")
+        void should_Fail_When_UnitNull() {
+            var draft = new ConsumptionDraft("input-batch-1", "article-1", "10", null);
+
+            var result = Consumption.create(draft);
+
+            assertThat(result.isFailure()).isTrue();
+            assertThat(result.unsafeGetError()).isInstanceOf(BatchError.InvalidConsumptionQuantity.class);
+        }
+
         @Test
         @DisplayName("should fail when unit is invalid")
         void should_Fail_When_UnitInvalid() {