refactor(ocr): move async training dispatch out of controller into SenderModelService

Controller was deciding when to fire runSenderTraining based on the returned run
status — a business rule that belongs in the service. Introduces @Lazy self-reference
to preserve @Async proxy dispatch without self-invocation bypassing Spring AOP.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/main/java/org/raddatz/familienarchiv/controller/OcrController.java

@@ -11,7 +11,6 @@ import org.raddatz.familienarchiv.dto.TriggerSenderTrainingDTO;
 import org.raddatz.familienarchiv.model.AppUser;
 import org.raddatz.familienarchiv.model.OcrJob;
 import org.raddatz.familienarchiv.model.OcrTrainingRun;
-import org.raddatz.familienarchiv.model.TrainingStatus;
 import org.raddatz.familienarchiv.security.Permission;
 import org.raddatz.familienarchiv.security.RequirePermission;
 import org.raddatz.familienarchiv.service.OcrBatchService;
@@ -156,11 +155,7 @@ public class OcrController {
     @ResponseStatus(HttpStatus.ACCEPTED)
     @RequirePermission(Permission.ADMIN)
     public OcrTrainingRun triggerSenderTraining(@Valid @RequestBody TriggerSenderTrainingDTO dto) {
-        OcrTrainingRun run = senderModelService.triggerManualSenderTraining(dto.personId());
-        if (run.getStatus() == TrainingStatus.RUNNING) {
-            senderModelService.runSenderTraining(dto.personId());
-        }
-        return run;
+        return senderModelService.triggerManualSenderTraining(dto.personId());
     }
 
     private UUID resolveUserId(Authentication authentication) {

backend/src/main/java/org/raddatz/familienarchiv/service/SenderModelService.java

@@ -9,7 +9,9 @@ import org.raddatz.familienarchiv.repository.OcrTrainingRunRepository;
 import org.raddatz.familienarchiv.repository.SenderModelRepository;
 import org.raddatz.familienarchiv.repository.TranscriptionBlockRepository;
 import org.slf4j.MDC;
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Lazy;
 import org.springframework.scheduling.annotation.Async;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
@@ -35,6 +37,11 @@ public class SenderModelService {
     private final TrainingDataExportService trainingDataExportService;
     private final PersonService personService;
 
+    // Self-reference through the Spring proxy so @Async is honoured on self-calls.
+    @Lazy
+    @Autowired
+    private SenderModelService self;
+
     @Value("${ocr.sender-model.activation-threshold:100}")
     private int activationThreshold;
 
@@ -56,9 +63,13 @@ public class SenderModelService {
         long correctedLines = blockRepository.countManualKurrentBlocksByPerson(personId);
         boolean runNow = runOrQueueSenderTraining(personId, (int) correctedLines);
         TrainingStatus targetStatus = runNow ? TrainingStatus.RUNNING : TrainingStatus.QUEUED;
-        return trainingRunRepository.findFirstByPersonIdAndStatus(personId, targetStatus)
+        OcrTrainingRun run = trainingRunRepository.findFirstByPersonIdAndStatus(personId, targetStatus)
                 .orElseThrow(() -> new IllegalStateException(
                         "Expected " + targetStatus + " row for person " + personId));
+        if (runNow) {
+            self.runSenderTraining(personId);
+        }
+        return run;
     }
 
     @Async

backend/src/test/java/org/raddatz/familienarchiv/controller/OcrControllerTest.java

@@ -30,6 +30,8 @@ import java.util.Map;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyBoolean;
 import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
@@ -429,6 +431,23 @@ class OcrControllerTest {
                 .andExpect(jsonPath("$.status").value("QUEUED"));
     }
 
+    @Test
+    @WithMockUser(authorities = "ADMIN")
+    void triggerSenderTraining_doesNotCallRunSenderTraining_fromController() throws Exception {
+        UUID personId = UUID.randomUUID();
+        OcrTrainingRun run = OcrTrainingRun.builder()
+                .id(UUID.randomUUID()).status(TrainingStatus.RUNNING)
+                .personId(personId).blockCount(5).documentCount(0).modelName("sender_" + personId).build();
+        when(senderModelService.triggerManualSenderTraining(personId)).thenReturn(run);
+
+        mockMvc.perform(post("/api/ocr/train-sender")
+                        .contentType(MediaType.APPLICATION_JSON)
+                        .content("{\"personId\":\"" + personId + "\"}"))
+                .andExpect(status().isAccepted());
+
+        verify(senderModelService, never()).runSenderTraining(any());
+    }
+
     @Test
     @WithMockUser(authorities = "READ_ALL")
     void getDocumentOcrStatus_returnsNone_whenNoOcrJobExists() throws Exception {

backend/src/test/java/org/raddatz/familienarchiv/service/SenderModelServiceTest.java

@@ -34,6 +34,7 @@ class SenderModelServiceTest {
     TransactionTemplate txTemplate;
     TrainingDataExportService trainingDataExportService;
     PersonService personService;
+    SenderModelService selfProxy;
     SenderModelService service;
 
     UUID personId = UUID.randomUUID();
@@ -47,6 +48,7 @@ class SenderModelServiceTest {
         txTemplate = mock(TransactionTemplate.class);
         trainingDataExportService = mock(TrainingDataExportService.class);
         personService = mock(PersonService.class);
+        selfProxy = mock(SenderModelService.class);
 
         // Execute transaction callbacks inline so unit tests run without a real DataSource.
         // lenient: not every test hits the txTemplate path, but the setup is shared.
@@ -57,6 +59,7 @@ class SenderModelServiceTest {
 
         service = new SenderModelService(senderModelRepository, blockRepository,
                 trainingRunRepository, ocrClient, txTemplate, trainingDataExportService, personService);
+        ReflectionTestUtils.setField(service, "self", selfProxy);
         ReflectionTestUtils.setField(service, "activationThreshold", 100);
         ReflectionTestUtils.setField(service, "retrainDelta", 50);
     }