.gitea/workflows/ci.yml

@@ -48,7 +48,7 @@ jobs:
           path: frontend/test-results/screenshots/
 
   # ─── OCR Service Unit Tests ───────────────────────────────────────────────────
-  # Only spell_check.py and test_confidence.py — no ML stack required.
+  # Only spell_check.py, test_confidence.py, test_sender_registry.py — no ML stack required.
   ocr-tests:
     name: OCR Service Tests
     runs-on: ubuntu-latest
@@ -60,11 +60,11 @@ jobs:
           python-version: '3.11'
 
       - name: Install test dependencies
-        run: pip install "pyspellchecker==0.9.0" pytest
+        run: pip install "pyspellchecker==0.9.0" pytest pytest-asyncio
         working-directory: ocr-service
 
       - name: Run OCR unit tests (no ML stack required)
-        run: python -m pytest test_spell_check.py test_confidence.py -v
+        run: python -m pytest test_spell_check.py test_confidence.py test_sender_registry.py -v
         working-directory: ocr-service
 
   # ─── Backend Unit & Slice Tests ───────────────────────────────────────────────

backend/src/main/java/org/raddatz/familienarchiv/model/OcrTrainingRun.java

@@ -59,6 +59,9 @@ public class OcrTrainingRun {
     @Column(name = "triggered_by")
     private UUID triggeredBy;
 
+    @Column(name = "person_id")
+    private UUID personId;
+
     @CreationTimestamp
     @Column(name = "created_at", nullable = false, updatable = false)
     @Schema(requiredMode = Schema.RequiredMode.REQUIRED)

backend/src/main/java/org/raddatz/familienarchiv/model/SenderModel.java

@@ -0,0 +1,56 @@
+package org.raddatz.familienarchiv.model;
+
+import com.fasterxml.jackson.annotation.JsonIgnore;
+import io.swagger.v3.oas.annotations.media.Schema;
+import jakarta.persistence.*;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.time.Instant;
+import java.util.UUID;
+
+@Entity
+@Table(name = "sender_models")
+@Data
+@NoArgsConstructor
+@AllArgsConstructor
+@Builder
+public class SenderModel {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.UUID)
+    @Schema(requiredMode = Schema.RequiredMode.REQUIRED)
+    private UUID id;
+
+    @Column(name = "person_id", nullable = false, unique = true)
+    @Schema(requiredMode = Schema.RequiredMode.REQUIRED)
+    private UUID personId;
+
+    @JsonIgnore
+    @Column(name = "model_path", nullable = false)
+    private String modelPath;
+
+    @Column
+    private Double accuracy;
+
+    @Column
+    private Double cer;
+
+    @Column(name = "corrected_lines_at_training", nullable = false)
+    @Schema(requiredMode = Schema.RequiredMode.REQUIRED)
+    private int correctedLinesAtTraining;
+
+    @CreationTimestamp
+    @Column(name = "created_at", nullable = false, updatable = false)
+    @Schema(requiredMode = Schema.RequiredMode.REQUIRED)
+    private Instant createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at", nullable = false)
+    @Schema(requiredMode = Schema.RequiredMode.REQUIRED)
+    private Instant updatedAt;
+}

backend/src/main/java/org/raddatz/familienarchiv/model/TrainingStatus.java

@@ -1,6 +1,7 @@
 package org.raddatz.familienarchiv.model;
 
 public enum TrainingStatus {
+    QUEUED,
     RUNNING,
     DONE,
     FAILED

backend/src/main/java/org/raddatz/familienarchiv/repository/OcrTrainingRunRepository.java

@@ -12,5 +12,11 @@ public interface OcrTrainingRunRepository extends JpaRepository<OcrTrainingRun,
 
     Optional<OcrTrainingRun> findFirstByStatus(TrainingStatus status);
 
-    List<OcrTrainingRun> findTop10ByOrderByCreatedAtDesc();
+    Optional<OcrTrainingRun> findFirstByStatusOrderByCreatedAtAsc(TrainingStatus status);
+
+    Optional<OcrTrainingRun> findFirstByPersonIdAndStatus(UUID personId, TrainingStatus status);
+
+    boolean existsByPersonIdAndStatus(UUID personId, TrainingStatus status);
+
+    List<OcrTrainingRun> findTop20ByOrderByCreatedAtDesc();
 }

backend/src/main/java/org/raddatz/familienarchiv/repository/SenderModelRepository.java

@@ -0,0 +1,12 @@
+package org.raddatz.familienarchiv.repository;
+
+import org.raddatz.familienarchiv.model.SenderModel;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.Optional;
+import java.util.UUID;
+
+public interface SenderModelRepository extends JpaRepository<SenderModel, UUID> {
+
+    Optional<SenderModel> findByPersonId(UUID personId);
+}

backend/src/main/java/org/raddatz/familienarchiv/repository/TranscriptionBlockRepository.java

@@ -3,6 +3,7 @@ package org.raddatz.familienarchiv.repository;
 import org.raddatz.familienarchiv.model.TranscriptionBlock;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 
 import java.util.List;
 import java.util.Optional;
@@ -37,4 +38,22 @@ public interface TranscriptionBlockRepository extends JpaRepository<Transcriptio
             AND 'KURRENT_SEGMENTATION' MEMBER OF d.trainingLabels
             """)
     List<TranscriptionBlock> findSegmentationBlocks();
+
+    @Query("""
+            SELECT COUNT(b) FROM TranscriptionBlock b
+            JOIN Document d ON d.id = b.documentId
+            WHERE b.source = 'MANUAL'
+            AND d.sender.id = :personId
+            AND d.scriptType = 'HANDWRITING_KURRENT'
+            """)
+    long countManualKurrentBlocksByPerson(@Param("personId") UUID personId);
+
+    @Query("""
+            SELECT b FROM TranscriptionBlock b
+            JOIN Document d ON d.id = b.documentId
+            WHERE b.source = 'MANUAL'
+            AND d.sender.id = :personId
+            AND d.scriptType = 'HANDWRITING_KURRENT'
+            """)
+    List<TranscriptionBlock> findManualKurrentBlocksByPerson(@Param("personId") UUID personId);
 }

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

@@ -9,10 +9,12 @@ import org.raddatz.familienarchiv.repository.OcrJobRepository;
 import org.springframework.scheduling.annotation.Async;
 import org.springframework.stereotype.Component;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.UUID;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
 
 @Component
 @RequiredArgsConstructor
@@ -29,6 +31,7 @@ public class OcrAsyncRunner {
     private final OcrJobRepository ocrJobRepository;
     private final OcrJobDocumentRepository ocrJobDocumentRepository;
     private final OcrProgressService ocrProgressService;
+    private final SenderModelService senderModelService;
 
     @Async
     public void runSingleDocument(UUID jobId, UUID documentId, UUID userId) {
@@ -68,12 +71,18 @@ public class OcrAsyncRunner {
 
             String pdfUrl = fileService.generatePresignedUrl(doc.getFilePath());
 
+            String senderModelPath = null;
+            if (doc.getSender() != null && doc.getScriptType() == ScriptType.HANDWRITING_KURRENT) {
+                senderModelPath = senderModelService.maybeGetModelPath(doc.getSender().getId()).orElse(null);
+            }
+
             AtomicInteger blockCounter = new AtomicInteger(0);
             AtomicInteger currentPage = new AtomicInteger(0);
             AtomicInteger skippedPages = new AtomicInteger(0);
             AtomicInteger totalPages = new AtomicInteger(0);
 
-            ocrClient.streamBlocks(pdfUrl, doc.getScriptType(), regions, event -> {
+            final String finalSenderModelPath = senderModelPath;
+            ocrClient.streamBlocks(pdfUrl, doc.getScriptType(), regions, finalSenderModelPath, event -> {
                 switch (event) {
                     case OcrStreamEvent.Start start -> {
                         totalPages.set(start.totalPages());
@@ -207,7 +216,25 @@ public class OcrAsyncRunner {
         clearExistingBlocks(documentId);
 
         String pdfUrl = fileService.generatePresignedUrl(doc.getFilePath());
-        List<OcrBlockResult> blocks = ocrClient.extractBlocks(pdfUrl, doc.getScriptType());
+
+        String senderModelPath = null;
+        if (doc.getSender() != null && doc.getScriptType() == ScriptType.HANDWRITING_KURRENT) {
+            senderModelPath = senderModelService.maybeGetModelPath(doc.getSender().getId()).orElse(null);
+        }
+
+        final AtomicReference<List<OcrBlockResult>> blocksRef = new AtomicReference<>();
+        final String finalSenderModelPath = senderModelPath;
+        ocrClient.streamBlocks(pdfUrl, doc.getScriptType(), null, finalSenderModelPath, event -> {
+            switch (event) {
+                case OcrStreamEvent.Page page -> {
+                    blocksRef.compareAndSet(null, new ArrayList<>());
+                    blocksRef.get().addAll(page.blocks());
+                }
+                default -> {}
+            }
+        });
+
+        List<OcrBlockResult> blocks = blocksRef.get() != null ? blocksRef.get() : List.of();
         createTranscriptionBlocks(documentId, blocks, userId, doc.getFileHash());
     }
 

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

@@ -1,6 +1,7 @@
 package org.raddatz.familienarchiv.service;
 
 import org.raddatz.familienarchiv.model.ScriptType;
+import org.springframework.lang.Nullable;
 
 import java.util.ArrayList;
 import java.util.LinkedHashMap;
@@ -37,15 +38,27 @@ public interface OcrClient {
     TrainingResult segtrainModel(byte[] trainingDataZip);
 
     /**
-     * Stream OCR results page-by-page via NDJSON. Implementations should override
+     * Fine-tune the Kurrent model for a specific sender.
-     * this method. The default exists only for backward compatibility during migration
-     * — it calls extractBlocks() and synthesizes events from the collected result.
      *
-     * @param regions optional list of pre-drawn annotation regions; when non-null,
+     * @param trainingDataZip raw ZIP bytes produced by TrainingDataExportService.exportForSender()
-     *                the OCR service runs in guided mode (crop + recognize per region)
+     * @param outputModelPath where to save the trained model (e.g. /app/models/sender_{uuid}.mlmodel)
+     * @return training result metrics
+     */
+    TrainingResult trainSenderModel(byte[] trainingDataZip, String outputModelPath);
+
+    /**
+     * Stream OCR results page-by-page via NDJSON, optionally using a sender-specific model.
+     * The default implementation synthesizes events from extractBlocks() for backward compatibility.
+     * Implementations that support real streaming (e.g. RestClientOcrClient) override this.
+     *
+     * @param regions         optional list of pre-drawn annotation regions; when non-null,
+     *                        the OCR service runs in guided mode (crop + recognize per region)
+     * @param senderModelPath optional path to a per-sender model file; null means use base model
      */
     default void streamBlocks(String pdfUrl, ScriptType scriptType,
-                               List<OcrRegion> regions, Consumer<OcrStreamEvent> handler) {
+                               List<OcrRegion> regions,
+                               @Nullable String senderModelPath,
+                               Consumer<OcrStreamEvent> handler) {
         List<OcrBlockResult> allBlocks = extractBlocks(pdfUrl, scriptType);
 
         LinkedHashMap<Integer, List<OcrBlockResult>> byPage = new LinkedHashMap<>();
@@ -62,4 +75,9 @@ public interface OcrClient {
 
         handler.accept(new OcrStreamEvent.Done(allBlocks.size(), 0));
     }
+
+    default void streamBlocks(String pdfUrl, ScriptType scriptType,
+                               List<OcrRegion> regions, Consumer<OcrStreamEvent> handler) {
+        streamBlocks(pdfUrl, scriptType, regions, null, handler);
+    }
 }

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

@@ -17,9 +17,11 @@ import org.springframework.transaction.support.TransactionTemplate;
 
 import java.io.ByteArrayOutputStream;
 import java.time.Instant;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.UUID;
 
 @Service
@@ -34,6 +36,7 @@ public class OcrTrainingService {
     private final OcrHealthClient ocrHealthClient;
     private final TranscriptionBlockRepository blockRepository;
     private final TransactionTemplate txTemplate;
+    private final PersonService personService;
 
     public record TrainingInfoResponse(
             int availableBlocks,
@@ -42,7 +45,8 @@ public class OcrTrainingService {
             int availableSegBlocks,
             boolean ocrServiceAvailable,
             OcrTrainingRun lastRun,
-            List<OcrTrainingRun> runs
+            List<OcrTrainingRun> runs,
+            Map<String, String> personNames
     ) {}
 
     private void assertNoRunningTraining() {
@@ -195,9 +199,20 @@ public class OcrTrainingService {
         int totalOcrBlocks = (int) blockRepository.count();
         int availableSegBlocks = segmentationTrainingExportService.querySegmentationBlocks().size();
 
-        List<OcrTrainingRun> recentRuns = trainingRunRepository.findTop10ByOrderByCreatedAtDesc();
+        List<OcrTrainingRun> recentRuns = trainingRunRepository.findTop20ByOrderByCreatedAtDesc();
         OcrTrainingRun lastRun = recentRuns.isEmpty() ? null : recentRuns.get(0);
 
+        List<UUID> distinctPersonIds = recentRuns.stream()
+                .map(OcrTrainingRun::getPersonId)
+                .filter(Objects::nonNull)
+                .distinct()
+                .toList();
+        Map<String, String> personNames = new HashMap<>();
+        if (!distinctPersonIds.isEmpty()) {
+            personService.getAllById(distinctPersonIds)
+                    .forEach(p -> personNames.put(p.getId().toString(), p.getDisplayName()));
+        }
+
         return new TrainingInfoResponse(
                 eligibleBlocks.size(),
                 totalOcrBlocks,
@@ -205,7 +220,8 @@ public class OcrTrainingService {
                 availableSegBlocks,
                 ocrHealthClient.isHealthy(),
                 lastRun,
-                recentRuns
+                recentRuns,
+                personNames
         );
     }
 
@@ -224,15 +240,4 @@ public class OcrTrainingService {
         });
     }
 
-    public Map<String, Object> buildTrainingInfoMap(TrainingInfoResponse info) {
-        return Map.of(
-                "availableBlocks", info.availableBlocks(),
-                "totalOcrBlocks", info.totalOcrBlocks(),
-                "availableDocuments", info.availableDocuments(),
-                "availableSegBlocks", info.availableSegBlocks(),
-                "ocrServiceAvailable", info.ocrServiceAvailable(),
-                "lastRun", info.lastRun() != null ? info.lastRun() : Map.of(),
-                "runs", info.runs()
-        );
-    }
 }

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

@@ -14,6 +14,7 @@ import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
 import org.springframework.http.client.JdkClientHttpRequestFactory;
+import org.springframework.lang.Nullable;
 import org.springframework.stereotype.Component;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
@@ -102,6 +103,13 @@ public class RestClientOcrClient implements OcrClient, OcrHealthClient {
                 .toList();
     }
 
+    private RestClient.RequestBodySpec addTrainingAuth(RestClient.RequestBodySpec spec) {
+        if (trainingToken != null && !trainingToken.isBlank()) {
+            return spec.header("X-Training-Token", trainingToken);
+        }
+        return spec;
+    }
+
     @Override
     public OcrClient.TrainingResult trainModel(byte[] trainingDataZip) {
         ByteArrayResource zipResource = new ByteArrayResource(trainingDataZip) {
@@ -114,15 +122,10 @@ public class RestClientOcrClient implements OcrClient, OcrHealthClient {
         partHeaders.setContentType(MediaType.parseMediaType("application/zip"));
         body.add("file", new HttpEntity<>(zipResource, partHeaders));
 
-        var spec = trainingRestClient.post()
+        TrainingResultJson result = addTrainingAuth(
-                .uri("/train")
+                trainingRestClient.post()
-                .contentType(MediaType.MULTIPART_FORM_DATA);
+                        .uri("/train")
-
+                        .contentType(MediaType.MULTIPART_FORM_DATA))
-        if (trainingToken != null && !trainingToken.isBlank()) {
-            spec = spec.header("X-Training-Token", trainingToken);
-        }
-
-        TrainingResultJson result = spec
                 .body(body)
                 .retrieve()
                 .body(TrainingResultJson.class);
@@ -143,15 +146,35 @@ public class RestClientOcrClient implements OcrClient, OcrHealthClient {
         partHeaders.setContentType(MediaType.parseMediaType("application/zip"));
         body.add("file", new HttpEntity<>(zipResource, partHeaders));
 
-        var spec = trainingRestClient.post()
+        TrainingResultJson result = addTrainingAuth(
-                .uri("/segtrain")
+                trainingRestClient.post()
-                .contentType(MediaType.MULTIPART_FORM_DATA);
+                        .uri("/segtrain")
+                        .contentType(MediaType.MULTIPART_FORM_DATA))
+                .body(body)
+                .retrieve()
+                .body(TrainingResultJson.class);
 
-        if (trainingToken != null && !trainingToken.isBlank()) {
+        if (result == null) return new OcrClient.TrainingResult(null, null, null, null);
-            spec = spec.header("X-Training-Token", trainingToken);
+        return new OcrClient.TrainingResult(result.loss(), result.accuracy(), result.cer(), result.epochs());
-        }
+    }
 
-        TrainingResultJson result = spec
+    @Override
+    public OcrClient.TrainingResult trainSenderModel(byte[] trainingDataZip, String outputModelPath) {
+        ByteArrayResource zipResource = new ByteArrayResource(trainingDataZip) {
+            @Override
+            public String getFilename() { return "sender-training-data.zip"; }
+        };
+
+        MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
+        HttpHeaders partHeaders = new HttpHeaders();
+        partHeaders.setContentType(MediaType.parseMediaType("application/zip"));
+        body.add("file", new HttpEntity<>(zipResource, partHeaders));
+        body.add("output_model_path", outputModelPath);
+
+        TrainingResultJson result = addTrainingAuth(
+                trainingRestClient.post()
+                        .uri("/train-sender")
+                        .contentType(MediaType.MULTIPART_FORM_DATA))
                 .body(body)
                 .retrieve()
                 .body(TrainingResultJson.class);
@@ -176,7 +199,8 @@ public class RestClientOcrClient implements OcrClient, OcrHealthClient {
 
     @Override
     public void streamBlocks(String pdfUrl, ScriptType scriptType,
-                              List<OcrRegion> regions, Consumer<OcrStreamEvent> handler) {
+                              List<OcrRegion> regions, @Nullable String senderModelPath,
+                              Consumer<OcrStreamEvent> handler) {
         String body;
         try {
             var requestMap = new java.util.LinkedHashMap<String, Object>();
@@ -186,6 +210,9 @@ public class RestClientOcrClient implements OcrClient, OcrHealthClient {
             if (regions != null && !regions.isEmpty()) {
                 requestMap.put("regions", regions);
             }
+            if (senderModelPath != null) {
+                requestMap.put("senderModelPath", senderModelPath);
+            }
             body = NDJSON_MAPPER.writeValueAsString(requestMap);
         } catch (IOException e) {
             throw new RuntimeException("Failed to serialize OCR request", e);
@@ -204,7 +231,12 @@ public class RestClientOcrClient implements OcrClient, OcrHealthClient {
 
             if (response.statusCode() == 404) {
                 log.info("OCR service does not support /ocr/stream (404), falling back to /ocr");
-                OcrClient.super.streamBlocks(pdfUrl, scriptType, regions, handler);
+                List<OcrBlockResult> allBlocks = extractBlocks(pdfUrl, scriptType);
+                handler.accept(new OcrStreamEvent.Start(0));
+                for (OcrBlockResult block : allBlocks) {
+                    handler.accept(new OcrStreamEvent.Page(block.pageNumber(), List.of(block)));
+                }
+                handler.accept(new OcrStreamEvent.Done(allBlocks.size(), 0));
                 return;
             }
 

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

@@ -0,0 +1,197 @@
+package org.raddatz.familienarchiv.service;
+
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.raddatz.familienarchiv.model.OcrTrainingRun;
+import org.raddatz.familienarchiv.model.SenderModel;
+import org.raddatz.familienarchiv.model.TrainingStatus;
+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.Value;
+import org.springframework.scheduling.annotation.Async;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+import org.springframework.transaction.support.TransactionTemplate;
+
+import java.io.ByteArrayOutputStream;
+import java.time.Instant;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.UUID;
+
+@Service
+@RequiredArgsConstructor
+@Slf4j
+public class SenderModelService {
+
+    private final SenderModelRepository senderModelRepository;
+    private final TranscriptionBlockRepository blockRepository;
+    private final OcrTrainingRunRepository trainingRunRepository;
+    private final OcrClient ocrClient;
+    private final TransactionTemplate txTemplate;
+    private final TrainingDataExportService trainingDataExportService;
+
+    @Value("${ocr.sender-model.activation-threshold:100}")
+    private int activationThreshold;
+
+    @Value("${ocr.sender-model.retrain-delta:50}")
+    private int retrainDelta;
+
+    /** Returns the model path if a trained sender model exists for this person. */
+    public Optional<String> maybeGetModelPath(UUID personId) {
+        return senderModelRepository.findByPersonId(personId)
+                .map(SenderModel::getModelPath);
+    }
+
+    /**
+     * Called after every MANUAL block save for HANDWRITING_KURRENT documents.
+     * Checks activation and retrain thresholds; enqueues or starts sender training when met.
+     */
+    @Async
+    public void checkAndTriggerTraining(UUID personId) {
+        long correctedLines = blockRepository.countManualKurrentBlocksByPerson(personId);
+        Optional<SenderModel> existing = senderModelRepository.findByPersonId(personId);
+
+        boolean shouldActivate = existing.isEmpty() && correctedLines >= activationThreshold;
+        boolean shouldRetrain = existing.isPresent()
+                && (correctedLines - existing.get().getCorrectedLinesAtTraining()) >= retrainDelta;
+
+        if (!shouldActivate && !shouldRetrain) {
+            return;
+        }
+
+        log.info("Sender training threshold met for person {} (correctedLines={}, activate={}, retrain={})",
+                personId, correctedLines, shouldActivate, shouldRetrain);
+
+        boolean runNow = runOrQueueSenderTraining(personId, (int) correctedLines);
+        if (runNow) {
+            triggerSenderTraining(personId, (int) correctedLines);
+        }
+    }
+
+    /**
+     * Atomically checks the queue state and either creates a RUNNING row (returns true) or a
+     * QUEUED row (returns false). All three operations — idle check, duplicate-queue guard, and
+     * RUNNING row creation — happen in one transaction, eliminating the race window that would
+     * otherwise exist between the check and a separate RUNNING row creation.
+     */
+    @Transactional
+    public boolean runOrQueueSenderTraining(UUID personId, int correctedLines) {
+        if (trainingRunRepository.existsByPersonIdAndStatus(personId, TrainingStatus.QUEUED)) {
+            log.info("Sender training already queued for person {} — skipping duplicate trigger", personId);
+            return false;
+        }
+
+        if (trainingRunRepository.findFirstByStatus(TrainingStatus.RUNNING).isPresent()) {
+            int blockCount = (int) blockRepository.countManualKurrentBlocksByPerson(personId);
+            trainingRunRepository.save(OcrTrainingRun.builder()
+                    .status(TrainingStatus.QUEUED)
+                    .personId(personId)
+                    .blockCount(blockCount)
+                    .documentCount(0)
+                    .modelName("sender_" + personId)
+                    .build());
+            log.info("Queued sender training for person {} — training already running", personId);
+            return false;
+        }
+
+        long blockCount = blockRepository.countManualKurrentBlocksByPerson(personId);
+        trainingRunRepository.save(OcrTrainingRun.builder()
+                .status(TrainingStatus.RUNNING)
+                .personId(personId)
+                .blockCount((int) blockCount)
+                .documentCount(0)
+                .modelName("sender_" + personId)
+                .build());
+        return true;
+    }
+
+    /**
+     * Executes sender training synchronously. Caller must run this on a background thread.
+     * The RUNNING row is expected to already exist — created atomically by
+     * runOrQueueSenderTraining (for new runs) or by promoteNextQueuedRun (for promoted runs).
+     */
+    public void triggerSenderTraining(UUID personId, int correctedLines) {
+        String outputModelPath = "/app/models/sender_" + personId + ".mlmodel";
+
+        OcrTrainingRun run = Objects.requireNonNull(txTemplate.execute(status ->
+                trainingRunRepository.findFirstByPersonIdAndStatus(personId, TrainingStatus.RUNNING)
+                        .orElseThrow(() -> new IllegalStateException(
+                                "Expected RUNNING row for person " + personId + " but none found"))));
+
+        String runId = run.getId().toString();
+        MDC.put("trainingRunId", runId);
+        log.info("Started sender training run {} for person {}", runId, personId);
+
+        try {
+            byte[] zipBytes = exportSenderData(personId);
+            log.info("[trainingRun={}] Sending {} bytes to OCR service for sender training", runId, zipBytes.length);
+            OcrClient.TrainingResult result = ocrClient.trainSenderModel(zipBytes, outputModelPath);
+
+            txTemplate.execute(status -> {
+                SenderModel model = senderModelRepository.findByPersonId(personId)
+                        .orElseGet(() -> SenderModel.builder().personId(personId).build());
+                model.setModelPath(outputModelPath);
+                model.setCer(result.cer());
+                model.setAccuracy(result.accuracy());
+                model.setCorrectedLinesAtTraining(correctedLines);
+                senderModelRepository.save(model);
+
+                run.setStatus(TrainingStatus.DONE);
+                run.setCompletedAt(Instant.now());
+                run.setCer(result.cer());
+                run.setAccuracy(result.accuracy());
+                run.setEpochs(result.epochs());
+                trainingRunRepository.save(run);
+                log.info("[trainingRun={}] Sender training completed — cer={}", runId, result.cer());
+                return null;
+            });
+        } catch (Exception e) {
+            txTemplate.execute(status -> {
+                run.setStatus(TrainingStatus.FAILED);
+                run.setErrorMessage(e.getMessage());
+                run.setCompletedAt(Instant.now());
+                trainingRunRepository.save(run);
+                log.error("[trainingRun={}] Sender training failed: {}", runId, e.getMessage(), e);
+                return null;
+            });
+        } finally {
+            MDC.remove("trainingRunId");
+            promoteNextQueuedRun();
+        }
+    }
+
+    private byte[] exportSenderData(UUID personId) throws java.io.IOException {
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        trainingDataExportService.exportForSender(personId).writeTo(baos);
+        return baos.toByteArray();
+    }
+
+    /**
+     * Promotes the oldest QUEUED sender run to RUNNING and triggers its training.
+     * Called in the finally block of triggerSenderTraining, creating a sequential chain:
+     * each run promotes the next only after it fully completes (success or failure).
+     *
+     * This is intentionally tail-recursive via the @Async thread: the same thread holds the
+     * full queue drain, serialising all sender training runs naturally without an external
+     * scheduler. With N queued runs the thread stays occupied for N sequential trainings —
+     * acceptable because the @Async executor is dedicated to long-running background work.
+     */
+    private void promoteNextQueuedRun() {
+        Optional<OcrTrainingRun> queuedOpt = txTemplate.execute(status ->
+                trainingRunRepository.findFirstByStatusOrderByCreatedAtAsc(TrainingStatus.QUEUED)
+                        .map(queued -> {
+                            queued.setStatus(TrainingStatus.RUNNING);
+                            return trainingRunRepository.save(queued);
+                        }));
+
+        if (queuedOpt != null && queuedOpt.isPresent()) {
+            OcrTrainingRun promoted = queuedOpt.get();
+            log.info("Promoting queued sender training run {} for person {}", promoted.getId(), promoted.getPersonId());
+            long freshCount = blockRepository.countManualKurrentBlocksByPerson(promoted.getPersonId());
+            triggerSenderTraining(promoted.getPersonId(), (int) freshCount);
+        }
+    }
+}

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

@@ -38,10 +38,20 @@ public class TrainingDataExportService {
     }
 
     public StreamingResponseBody exportToZip() {
-        // Collect all data before entering the lambda — no open DB txn during streaming
+        return exportBlocksToZip(queryEligibleBlocks());
-        List<TranscriptionBlock> blocks = queryEligibleBlocks();
+    }
+
+    public List<TranscriptionBlock> queryBlocksForSender(UUID personId) {
+        return blockRepository.findManualKurrentBlocksByPerson(personId);
+    }
+
+    public StreamingResponseBody exportForSender(UUID personId) {
+        return exportBlocksToZip(queryBlocksForSender(personId));
+    }
+
+    private StreamingResponseBody exportBlocksToZip(List<TranscriptionBlock> blocks) {
         if (blocks.isEmpty()) {
-            return out -> {}; // caller checks isEmpty() for 204 response
+            return out -> {};
         }
 
         // Group blocks by documentId so we only download each PDF once

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

@@ -11,6 +11,7 @@ import org.raddatz.familienarchiv.exception.ErrorCode;
 import org.raddatz.familienarchiv.model.BlockSource;
 import org.raddatz.familienarchiv.model.Document;
 import org.raddatz.familienarchiv.model.DocumentAnnotation;
+import org.raddatz.familienarchiv.model.ScriptType;
 import org.raddatz.familienarchiv.model.TranscriptionBlock;
 import org.raddatz.familienarchiv.model.TranscriptionBlockVersion;
 import org.raddatz.familienarchiv.repository.AnnotationRepository;
@@ -35,6 +36,7 @@ public class TranscriptionService {
     private final AnnotationRepository annotationRepository;
     private final AnnotationService annotationService;
     private final DocumentService documentService;
+    private final SenderModelService senderModelService;
 
     public List<TranscriptionBlock> listBlocks(UUID documentId) {
         return blockRepository.findByDocumentIdOrderBySortOrderAsc(documentId);
@@ -122,6 +124,7 @@ public class TranscriptionService {
 
         String text = sanitizeText(dto.getText());
         block.setText(text);
+        block.setSource(BlockSource.MANUAL);
         if (dto.getLabel() != null) {
             block.setLabel(dto.getLabel());
         }
@@ -129,6 +132,12 @@ public class TranscriptionService {
 
         TranscriptionBlock saved = blockRepository.save(block);
         saveVersion(saved, userId);
+
+        Document doc = documentService.getDocumentById(documentId);
+        if (doc.getSender() != null && doc.getScriptType() == ScriptType.HANDWRITING_KURRENT) {
+            senderModelService.checkAndTriggerTraining(doc.getSender().getId());
+        }
+
         return saved;
     }
 

backend/src/main/resources/application.yaml

@@ -77,3 +77,8 @@ app:
       tags: 10
       summary: 11
       transcription: 13
+
+ocr:
+  sender-model:
+    activation-threshold: 100
+    retrain-delta: 50

backend/src/main/resources/db/migration/V40__add_sender_models.sql

@@ -0,0 +1,10 @@
+CREATE TABLE sender_models (
+    id                          UUID        PRIMARY KEY DEFAULT gen_random_uuid(),
+    person_id                   UUID        NOT NULL UNIQUE REFERENCES persons(id) ON DELETE CASCADE,
+    model_path                  TEXT        NOT NULL,
+    accuracy                    DOUBLE PRECISION,
+    cer                         DOUBLE PRECISION,
+    corrected_lines_at_training INT         NOT NULL DEFAULT 0,
+    created_at                  TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at                  TIMESTAMPTZ NOT NULL DEFAULT now()
+);

backend/src/main/resources/db/migration/V41__add_person_to_training_runs.sql

@@ -0,0 +1,2 @@
+ALTER TABLE ocr_training_runs
+    ADD COLUMN person_id UUID REFERENCES persons(id) ON DELETE SET NULL;

backend/src/main/resources/db/migration/V42__add_queued_per_person_unique_index.sql

@@ -0,0 +1,3 @@
+CREATE UNIQUE INDEX idx_training_runs_queued_per_person
+    ON ocr_training_runs(person_id)
+    WHERE status = 'QUEUED';

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

@@ -23,6 +23,8 @@ import org.springframework.test.web.servlet.MockMvc;
 import java.util.List;
 import java.util.UUID;
 
+import java.util.Map;
+
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyBoolean;
 import static org.mockito.ArgumentMatchers.eq;
@@ -219,7 +221,7 @@ class OcrControllerTest {
     @WithMockUser(authorities = "ADMIN")
     void getTrainingInfo_returns200_withInfo() throws Exception {
         OcrTrainingService.TrainingInfoResponse info =
-                new OcrTrainingService.TrainingInfoResponse(5, 20, 2, 3, true, null, List.of());
+                new OcrTrainingService.TrainingInfoResponse(5, 20, 2, 3, true, null, List.of(), Map.of());
         when(ocrTrainingService.getTrainingInfo()).thenReturn(info);
 
         mockMvc.perform(get("/api/ocr/training-info"))
@@ -228,6 +230,52 @@ class OcrControllerTest {
                 .andExpect(jsonPath("$.ocrServiceAvailable").value(true));
     }
 
+    @Test
+    @WithMockUser(authorities = "ADMIN")
+    void getTrainingInfo_returns200_and_omits_personName_when_service_provides_empty_map() throws Exception {
+        UUID personId = UUID.randomUUID();
+        OcrTrainingRun runWithPerson = OcrTrainingRun.builder()
+                .id(UUID.randomUUID()).status(TrainingStatus.DONE)
+                .personId(personId).blockCount(5).documentCount(1).modelName("sender_x").build();
+        OcrTrainingService.TrainingInfoResponse info =
+                new OcrTrainingService.TrainingInfoResponse(5, 20, 2, 3, true, null,
+                        List.of(runWithPerson), Map.of());
+        when(ocrTrainingService.getTrainingInfo()).thenReturn(info);
+
+        mockMvc.perform(get("/api/ocr/training-info"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.personNames").isEmpty());
+    }
+
+    @Test
+    @WithMockUser(authorities = "ADMIN")
+    void getTrainingInfo_includesPersonName_whenPersonIdResolves() throws Exception {
+        UUID personId = UUID.randomUUID();
+        OcrTrainingRun runWithPerson = OcrTrainingRun.builder()
+                .id(UUID.randomUUID()).status(TrainingStatus.DONE)
+                .personId(personId).blockCount(5).documentCount(1).modelName("sender_x").build();
+        OcrTrainingService.TrainingInfoResponse info =
+                new OcrTrainingService.TrainingInfoResponse(5, 20, 2, 3, true, null,
+                        List.of(runWithPerson), Map.of(personId.toString(), "Max Mustermann"));
+        when(ocrTrainingService.getTrainingInfo()).thenReturn(info);
+
+        mockMvc.perform(get("/api/ocr/training-info"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.personNames." + personId).value("Max Mustermann"));
+    }
+
+    @Test
+    @WithMockUser(authorities = "ADMIN")
+    void getTrainingInfo_serializes_null_lastRun_as_json_null() throws Exception {
+        OcrTrainingService.TrainingInfoResponse info =
+                new OcrTrainingService.TrainingInfoResponse(0, 0, 0, 0, false, null, List.of(), Map.of());
+        when(ocrTrainingService.getTrainingInfo()).thenReturn(info);
+
+        mockMvc.perform(get("/api/ocr/training-info"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.lastRun").doesNotExist());
+    }
+
     @Test
     @WithMockUser(authorities = "READ_ALL")
     void getDocumentOcrStatus_returnsNone_whenNoOcrJobExists() throws Exception {

backend/src/test/java/org/raddatz/familienarchiv/repository/MigrationIntegrationTest.java

@@ -217,8 +217,71 @@ class MigrationIntegrationTest {
         assertThat(stored).isEqualTo("sage");
     }
 
+    // ─── V42: idx_training_runs_queued_per_person partial unique index ────────
+
+    @Test
+    @Transactional(propagation = Propagation.NOT_SUPPORTED)
+    void v42_partialUniqueIndex_preventsTwoQueuedRunsForSamePerson() {
+        UUID personId = createPerson("V42Test", "SamePerson");
+        jdbc.update("""
+                INSERT INTO ocr_training_runs (id, status, block_count, document_count, model_name, person_id)
+                VALUES (gen_random_uuid(), 'QUEUED', 10, 2, 'sender_x', ?)
+                """, personId);
+
+        assertThatThrownBy(() ->
+                jdbc.update("""
+                        INSERT INTO ocr_training_runs (id, status, block_count, document_count, model_name, person_id)
+                        VALUES (gen_random_uuid(), 'QUEUED', 5, 1, 'sender_x', ?)
+                        """, personId)
+        ).isInstanceOf(DataIntegrityViolationException.class);
+
+        jdbc.update("DELETE FROM ocr_training_runs WHERE person_id = ?", personId);
+        jdbc.update("DELETE FROM persons WHERE id = ?", personId);
+    }
+
+    @Test
+    void v42_partialUniqueIndex_allowsQueuedRunsForDifferentPersons() {
+        UUID person1 = createPerson("V42Test", "PersonA");
+        UUID person2 = createPerson("V42Test", "PersonB");
+
+        int rows1 = jdbc.update("""
+                INSERT INTO ocr_training_runs (id, status, block_count, document_count, model_name, person_id)
+                VALUES (gen_random_uuid(), 'QUEUED', 10, 2, 'sender_a', ?)
+                """, person1);
+        int rows2 = jdbc.update("""
+                INSERT INTO ocr_training_runs (id, status, block_count, document_count, model_name, person_id)
+                VALUES (gen_random_uuid(), 'QUEUED', 5, 1, 'sender_b', ?)
+                """, person2);
+
+        assertThat(rows1).isEqualTo(1);
+        assertThat(rows2).isEqualTo(1);
+    }
+
+    @Test
+    void v42_partialUniqueIndex_allowsMultipleDoneRunsForSamePerson() {
+        UUID personId = createPerson("V42Test", "DonePerson");
+
+        int rows1 = jdbc.update("""
+                INSERT INTO ocr_training_runs (id, status, block_count, document_count, model_name, person_id)
+                VALUES (gen_random_uuid(), 'DONE', 10, 2, 'sender_x', ?)
+                """, personId);
+        int rows2 = jdbc.update("""
+                INSERT INTO ocr_training_runs (id, status, block_count, document_count, model_name, person_id)
+                VALUES (gen_random_uuid(), 'DONE', 15, 3, 'sender_x', ?)
+                """, personId);
+
+        assertThat(rows1).isEqualTo(1);
+        assertThat(rows2).isEqualTo(1);
+    }
+
     // ─── helpers ─────────────────────────────────────────────────────────────
 
+    private UUID createPerson(String firstName, String lastName) {
+        UUID id = UUID.randomUUID();
+        jdbc.update("INSERT INTO persons (id, first_name, last_name) VALUES (?, ?, ?)", id, firstName, lastName);
+        return id;
+    }
+
     private UUID createTag(String name) {
         UUID id = UUID.randomUUID();
         jdbc.update("INSERT INTO tag (id, name) VALUES (?, ?)", id, name);

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

@@ -31,6 +31,7 @@ class OcrAsyncRunnerTest {
     @Mock OcrJobRepository ocrJobRepository;
     @Mock OcrJobDocumentRepository ocrJobDocumentRepository;
     @Mock OcrProgressService ocrProgressService;
+    @Mock SenderModelService senderModelService;
 
     @InjectMocks OcrAsyncRunner ocrAsyncRunner;
 
@@ -42,7 +43,12 @@ class OcrAsyncRunnerTest {
                 .fileHash("hash").scriptType(ScriptType.TYPEWRITER).build();
 
         when(fileService.generatePresignedUrl(any())).thenReturn("http://presigned");
-        when(ocrClient.extractBlocks(any(), any())).thenReturn(List.of());
+        doAnswer(inv -> {
+            Consumer<OcrStreamEvent> handler = inv.getArgument(4);
+            handler.accept(new OcrStreamEvent.Start(0));
+            handler.accept(new OcrStreamEvent.Done(0, 0));
+            return null;
+        }).when(ocrClient).streamBlocks(any(), any(), any(), any(), any());
 
         ocrAsyncRunner.processDocument(docId, doc, userId);
 
@@ -59,9 +65,15 @@ class OcrAsyncRunnerTest {
 
 
         when(fileService.generatePresignedUrl(any())).thenReturn("http://presigned");
-        when(ocrClient.extractBlocks(any(), any())).thenReturn(List.of(
+        doAnswer(inv -> {
-                new OcrBlockResult(0, 0.1, 0.1, 0.8, 0.04, null, "Line 1", null),
+            Consumer<OcrStreamEvent> handler = inv.getArgument(4);
-                new OcrBlockResult(0, 0.1, 0.2, 0.8, 0.04, null, "Line 2", null)));
+            handler.accept(new OcrStreamEvent.Start(1));
+            handler.accept(new OcrStreamEvent.Page(0, List.of(
+                    new OcrBlockResult(0, 0.1, 0.1, 0.8, 0.04, null, "Line 1", null),
+                    new OcrBlockResult(0, 0.1, 0.2, 0.8, 0.04, null, "Line 2", null))));
+            handler.accept(new OcrStreamEvent.Done(2, 0));
+            return null;
+        }).when(ocrClient).streamBlocks(any(), any(), any(), any(), any());
         DocumentAnnotation ann = DocumentAnnotation.builder().id(annId).build();
         when(annotationService.createOcrAnnotation(any(), any(), any(), any(), any())).thenReturn(ann);
 
@@ -83,8 +95,14 @@ class OcrAsyncRunnerTest {
 
 
         when(fileService.generatePresignedUrl(any())).thenReturn("http://presigned");
-        when(ocrClient.extractBlocks(any(), any())).thenReturn(List.of(
+        doAnswer(inv -> {
-                new OcrBlockResult(0, 0.1, 0.1, 0.8, 0.04, null, "Test", null)));
+            Consumer<OcrStreamEvent> handler = inv.getArgument(4);
+            handler.accept(new OcrStreamEvent.Start(1));
+            handler.accept(new OcrStreamEvent.Page(0, List.of(
+                    new OcrBlockResult(0, 0.1, 0.1, 0.8, 0.04, null, "Test", null))));
+            handler.accept(new OcrStreamEvent.Done(1, 0));
+            return null;
+        }).when(ocrClient).streamBlocks(any(), any(), any(), any(), any());
         DocumentAnnotation ann = DocumentAnnotation.builder().id(annId).build();
         when(annotationService.createOcrAnnotation(any(), any(), any(), any(), any())).thenReturn(ann);
 
@@ -112,12 +130,12 @@ class OcrAsyncRunnerTest {
 
         when(fileService.generatePresignedUrl(any())).thenReturn("http://presigned");
         doAnswer(inv -> {
-            Consumer<OcrStreamEvent> handler = inv.getArgument(3);
+            Consumer<OcrStreamEvent> handler = inv.getArgument(4);
             handler.accept(new OcrStreamEvent.Start(1));
             handler.accept(new OcrStreamEvent.Page(0, List.of()));
             handler.accept(new OcrStreamEvent.Done(0, 0));
             return null;
-        }).when(ocrClient).streamBlocks(any(), any(), any(), any());
+        }).when(ocrClient).streamBlocks(any(), any(), any(), any(), any());
 
         ocrAsyncRunner.runSingleDocument(jobId, docId, userId);
 
@@ -142,7 +160,7 @@ class OcrAsyncRunnerTest {
         when(documentService.getDocumentById(docId)).thenReturn(doc);
 
         when(fileService.generatePresignedUrl(any())).thenReturn("http://presigned");
-        doThrow(new RuntimeException("OCR failed")).when(ocrClient).streamBlocks(any(), any(), any(), any());
+        doThrow(new RuntimeException("OCR failed")).when(ocrClient).streamBlocks(any(), any(), any(), any(), any());
 
         ocrAsyncRunner.runSingleDocument(jobId, docId, userId);
 
@@ -174,7 +192,7 @@ class OcrAsyncRunnerTest {
 
         List<String> progressMessages = new ArrayList<>();
         doAnswer(inv -> {
-            Consumer<OcrStreamEvent> handler = inv.getArgument(3);
+            Consumer<OcrStreamEvent> handler = inv.getArgument(4);
             handler.accept(new OcrStreamEvent.Start(3));
             handler.accept(new OcrStreamEvent.Page(0, List.of(
                     new OcrBlockResult(0, 0.1, 0.1, 0.8, 0.04, null, "L1", null),
@@ -185,7 +203,7 @@ class OcrAsyncRunnerTest {
             progressMessages.add(job.getProgressMessage());
             handler.accept(new OcrStreamEvent.Done(3, 0));
             return null;
-        }).when(ocrClient).streamBlocks(any(), any(), any(), any());
+        }).when(ocrClient).streamBlocks(any(), any(), any(), any(), any());
 
         ocrAsyncRunner.runSingleDocument(jobId, docId, userId);
 
@@ -215,14 +233,14 @@ class OcrAsyncRunnerTest {
         when(fileService.generatePresignedUrl(any())).thenReturn("http://presigned");
 
         doAnswer(inv -> {
-            Consumer<OcrStreamEvent> handler = inv.getArgument(3);
+            Consumer<OcrStreamEvent> handler = inv.getArgument(4);
             handler.accept(new OcrStreamEvent.Start(3));
             handler.accept(new OcrStreamEvent.Page(0, List.of()));
             handler.accept(new OcrStreamEvent.Error(1, "failed"));
             handler.accept(new OcrStreamEvent.Page(2, List.of()));
             handler.accept(new OcrStreamEvent.Done(0, 1));
             return null;
-        }).when(ocrClient).streamBlocks(any(), any(), any(), any());
+        }).when(ocrClient).streamBlocks(any(), any(), any(), any(), any());
 
         ocrAsyncRunner.runSingleDocument(jobId, docId, userId);
 
@@ -251,14 +269,14 @@ class OcrAsyncRunnerTest {
 
         List<String> progressMessages = new ArrayList<>();
         doAnswer(inv -> {
-            Consumer<OcrStreamEvent> handler = inv.getArgument(3);
+            Consumer<OcrStreamEvent> handler = inv.getArgument(4);
             handler.accept(new OcrStreamEvent.Start(5));
             handler.accept(new OcrStreamEvent.Preprocessing(1));
             progressMessages.add(job.getProgressMessage());
             handler.accept(new OcrStreamEvent.Page(1, List.of()));
             handler.accept(new OcrStreamEvent.Done(0, 0));
             return null;
-        }).when(ocrClient).streamBlocks(any(), any(), any(), any());
+        }).when(ocrClient).streamBlocks(any(), any(), any(), any(), any());
 
         ocrAsyncRunner.runSingleDocument(jobId, docId, userId);
 
@@ -287,13 +305,13 @@ class OcrAsyncRunnerTest {
         when(fileService.generatePresignedUrl(any())).thenReturn("http://presigned");
 
         doAnswer(inv -> {
-            Consumer<OcrStreamEvent> handler = inv.getArgument(3);
+            Consumer<OcrStreamEvent> handler = inv.getArgument(4);
             handler.accept(new OcrStreamEvent.Start(2));
             handler.accept(new OcrStreamEvent.Error(0, "some python traceback details"));
             handler.accept(new OcrStreamEvent.Page(1, List.of()));
             handler.accept(new OcrStreamEvent.Done(0, 1));
             return null;
-        }).when(ocrClient).streamBlocks(any(), any(), any(), any());
+        }).when(ocrClient).streamBlocks(any(), any(), any(), any(), any());
 
         ocrAsyncRunner.runSingleDocument(jobId, docId, userId);
 

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

@@ -21,6 +21,7 @@ class OcrClientDefaultStreamTest {
             }
             @Override public TrainingResult trainModel(byte[] zip) { return null; }
             @Override public TrainingResult segtrainModel(byte[] zip) { return null; }
+            @Override public TrainingResult trainSenderModel(byte[] zip, String path) { return null; }
         };
 
         List<OcrStreamEvent> events = new ArrayList<>();
@@ -52,6 +53,7 @@ class OcrClientDefaultStreamTest {
             @Override public List<OcrBlockResult> extractBlocks(String pdfUrl, ScriptType scriptType) { return List.of(); }
             @Override public TrainingResult trainModel(byte[] zip) { return null; }
             @Override public TrainingResult segtrainModel(byte[] zip) { return null; }
+            @Override public TrainingResult trainSenderModel(byte[] zip, String path) { return null; }
         };
 
         List<OcrStreamEvent> events = new ArrayList<>();

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

@@ -4,11 +4,12 @@ import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.raddatz.familienarchiv.exception.DomainException;
 import org.raddatz.familienarchiv.model.OcrTrainingRun;
-import org.raddatz.familienarchiv.model.TrainingLabel;
+import org.raddatz.familienarchiv.model.Person;
 import org.raddatz.familienarchiv.model.TrainingStatus;
 import org.raddatz.familienarchiv.model.TranscriptionBlock;
 import org.raddatz.familienarchiv.repository.OcrTrainingRunRepository;
 import org.raddatz.familienarchiv.repository.TranscriptionBlockRepository;
+import org.raddatz.familienarchiv.service.PersonService;
 import org.springframework.transaction.support.TransactionCallback;
 import org.springframework.transaction.support.TransactionTemplate;
 
@@ -32,6 +33,7 @@ class OcrTrainingServiceTest {
     OcrHealthClient healthClient;
     TranscriptionBlockRepository blockRepository;
     TransactionTemplate txTemplate;
+    PersonService personService;
     OcrTrainingService service;
 
     @BeforeEach
@@ -43,6 +45,7 @@ class OcrTrainingServiceTest {
         healthClient = mock(OcrHealthClient.class);
         blockRepository = mock(TranscriptionBlockRepository.class);
         txTemplate = mock(TransactionTemplate.class);
+        personService = mock(PersonService.class);
 
         // Execute transaction callbacks inline so unit tests run without a real DataSource
         when(txTemplate.execute(any())).thenAnswer(inv -> {
@@ -50,10 +53,10 @@ class OcrTrainingServiceTest {
             return callback.doInTransaction(null);
         });
 
-        service = new OcrTrainingService(runRepository, exportService, segExportService, ocrClient, healthClient, blockRepository, txTemplate);
+        service = new OcrTrainingService(runRepository, exportService, segExportService, ocrClient, healthClient, blockRepository, txTemplate, personService);
 
         when(blockRepository.count()).thenReturn(0L);
-        when(runRepository.findTop10ByOrderByCreatedAtDesc()).thenReturn(List.of());
+        when(runRepository.findTop20ByOrderByCreatedAtDesc()).thenReturn(List.of());
         when(segExportService.querySegmentationBlocks()).thenReturn(List.of());
     }
 
@@ -230,6 +233,37 @@ class OcrTrainingServiceTest {
                 run.getStatus() == TrainingStatus.FAILED && run.getErrorMessage() != null));
     }
 
+    // ─── getTrainingInfo: batch person name resolution ────────────────────────
+
+    @Test
+    void getTrainingInfo_resolves_person_names_in_single_batch_call() {
+        UUID personA = UUID.randomUUID();
+        UUID personB = UUID.randomUUID();
+        List<OcrTrainingRun> runs = List.of(
+                OcrTrainingRun.builder().id(UUID.randomUUID()).status(TrainingStatus.DONE)
+                        .personId(personA).blockCount(5).documentCount(1).modelName("sender_a").build(),
+                OcrTrainingRun.builder().id(UUID.randomUUID()).status(TrainingStatus.DONE)
+                        .personId(personB).blockCount(5).documentCount(1).modelName("sender_b").build(),
+                OcrTrainingRun.builder().id(UUID.randomUUID()).status(TrainingStatus.DONE)
+                        .personId(personA).blockCount(5).documentCount(1).modelName("sender_a").build()
+        );
+        when(runRepository.findTop20ByOrderByCreatedAtDesc()).thenReturn(runs);
+        when(exportService.queryEligibleBlocks()).thenReturn(List.of());
+
+        Person pa = Person.builder().id(personA).firstName("Anna").lastName("Müller").build();
+        Person pb = Person.builder().id(personB).firstName("Karl").lastName("Bauer").build();
+        when(personService.getAllById(argThat(ids -> ids.size() == 2 && ids.containsAll(List.of(personA, personB)))))
+                .thenReturn(List.of(pa, pb));
+        when(healthClient.isHealthy()).thenReturn(true);
+
+        OcrTrainingService.TrainingInfoResponse info = service.getTrainingInfo();
+
+        verify(personService, never()).getById(any());
+        verify(personService, times(1)).getAllById(any());
+        assertThat(info.personNames()).containsKey(personA.toString());
+        assertThat(info.personNames()).containsKey(personB.toString());
+    }
+
     // ─── Orphan recovery ──────────────────────────────────────────────────────
 
     @Test

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

@@ -0,0 +1,41 @@
+package org.raddatz.familienarchiv.service;
+
+import com.sun.net.httpserver.HttpServer;
+import org.junit.jupiter.api.Test;
+
+import java.io.OutputStream;
+import java.net.InetSocketAddress;
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class RestClientOcrClientTrainingTest {
+
+    @Test
+    void trainSenderModel_postsToTrainSenderEndpoint() throws Exception {
+        List<String> capturedPaths = new CopyOnWriteArrayList<>();
+        HttpServer server = HttpServer.create(new InetSocketAddress(0), 0);
+        server.createContext("/", exchange -> {
+            capturedPaths.add(exchange.getRequestURI().getPath());
+            byte[] response = "{\"loss\":0.1,\"accuracy\":0.95,\"cer\":0.05,\"epochs\":3}"
+                    .getBytes(StandardCharsets.UTF_8);
+            exchange.getResponseHeaders().set("Content-Type", "application/json");
+            exchange.sendResponseHeaders(200, response.length);
+            try (OutputStream os = exchange.getResponseBody()) {
+                os.write(response);
+            }
+        });
+        server.start();
+
+        try {
+            int port = server.getAddress().getPort();
+            RestClientOcrClient client = new RestClientOcrClient("http://localhost:" + port, "");
+            client.trainSenderModel(new byte[]{1, 2, 3}, "/app/models/sender_test.mlmodel");
+            assertThat(capturedPaths).contains("/train-sender");
+        } finally {
+            server.stop(0);
+        }
+    }
+}

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

@@ -0,0 +1,302 @@
+package org.raddatz.familienarchiv.service;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.raddatz.familienarchiv.model.OcrTrainingRun;
+import org.raddatz.familienarchiv.model.SenderModel;
+import org.raddatz.familienarchiv.model.TrainingStatus;
+import org.raddatz.familienarchiv.repository.OcrTrainingRunRepository;
+import org.raddatz.familienarchiv.repository.SenderModelRepository;
+import org.raddatz.familienarchiv.repository.TranscriptionBlockRepository;
+import org.springframework.test.util.ReflectionTestUtils;
+import org.springframework.transaction.support.TransactionCallback;
+import org.springframework.transaction.support.TransactionTemplate;
+
+import java.util.Optional;
+import java.util.UUID;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.*;
+import static org.mockito.Mockito.*;
+
+@ExtendWith(MockitoExtension.class)
+class SenderModelServiceTest {
+
+    SenderModelRepository senderModelRepository;
+    TranscriptionBlockRepository blockRepository;
+    OcrTrainingRunRepository trainingRunRepository;
+    OcrClient ocrClient;
+    TransactionTemplate txTemplate;
+    TrainingDataExportService trainingDataExportService;
+    SenderModelService service;
+
+    UUID personId = UUID.randomUUID();
+
+    @BeforeEach
+    void setUp() {
+        senderModelRepository = mock(SenderModelRepository.class);
+        blockRepository = mock(TranscriptionBlockRepository.class);
+        trainingRunRepository = mock(OcrTrainingRunRepository.class);
+        ocrClient = mock(OcrClient.class);
+        txTemplate = mock(TransactionTemplate.class);
+        trainingDataExportService = mock(TrainingDataExportService.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.
+        lenient().when(txTemplate.execute(any())).thenAnswer(inv -> {
+            TransactionCallback<?> callback = inv.getArgument(0);
+            return callback.doInTransaction(null);
+        });
+
+        service = new SenderModelService(senderModelRepository, blockRepository,
+                trainingRunRepository, ocrClient, txTemplate, trainingDataExportService);
+        ReflectionTestUtils.setField(service, "activationThreshold", 100);
+        ReflectionTestUtils.setField(service, "retrainDelta", 50);
+    }
+
+    // ─── Activation threshold ─────────────────────────────────────────────────
+
+    @Test
+    void checkAndTriggerTraining_doesNothing_belowActivationThreshold() {
+        when(blockRepository.countManualKurrentBlocksByPerson(personId)).thenReturn(99L);
+        when(senderModelRepository.findByPersonId(personId)).thenReturn(Optional.empty());
+
+        SenderModelService spy = spy(service);
+        spy.checkAndTriggerTraining(personId);
+
+        verify(spy, never()).runOrQueueSenderTraining(any(), anyInt());
+    }
+
+    @Test
+    void checkAndTriggerTraining_triggersTraining_atActivationThreshold() {
+        when(blockRepository.countManualKurrentBlocksByPerson(personId)).thenReturn(100L);
+        when(senderModelRepository.findByPersonId(personId)).thenReturn(Optional.empty());
+
+        SenderModelService spy = spy(service);
+        doReturn(false).when(spy).runOrQueueSenderTraining(personId, 100);
+
+        spy.checkAndTriggerTraining(personId);
+
+        verify(spy).runOrQueueSenderTraining(personId, 100);
+    }
+
+    // ─── Retrain delta ────────────────────────────────────────────────────────
+
+    @Test
+    void checkAndTriggerTraining_doesNothing_belowRetrainDelta() {
+        SenderModel existing = SenderModel.builder().personId(personId)
+                .correctedLinesAtTraining(100).build();
+        when(senderModelRepository.findByPersonId(personId)).thenReturn(Optional.of(existing));
+        when(blockRepository.countManualKurrentBlocksByPerson(personId)).thenReturn(149L);
+
+        SenderModelService spy = spy(service);
+        spy.checkAndTriggerTraining(personId);
+
+        verify(spy, never()).runOrQueueSenderTraining(any(), anyInt());
+    }
+
+    @Test
+    void checkAndTriggerTraining_triggersRetrain_atRetrainDelta() {
+        SenderModel existing = SenderModel.builder().personId(personId)
+                .correctedLinesAtTraining(100).build();
+        when(senderModelRepository.findByPersonId(personId)).thenReturn(Optional.of(existing));
+        when(blockRepository.countManualKurrentBlocksByPerson(personId)).thenReturn(150L);
+
+        SenderModelService spy = spy(service);
+        doReturn(false).when(spy).runOrQueueSenderTraining(personId, 150);
+
+        spy.checkAndTriggerTraining(personId);
+
+        verify(spy).runOrQueueSenderTraining(personId, 150);
+    }
+
+    // ─── runNow flag ──────────────────────────────────────────────────────────
+
+    @Test
+    void checkAndTriggerTraining_callsTrigger_whenRunNow() {
+        when(blockRepository.countManualKurrentBlocksByPerson(personId)).thenReturn(100L);
+        when(senderModelRepository.findByPersonId(personId)).thenReturn(Optional.empty());
+
+        SenderModelService spy = spy(service);
+        doReturn(true).when(spy).runOrQueueSenderTraining(personId, 100);
+        doNothing().when(spy).triggerSenderTraining(personId, 100);
+
+        spy.checkAndTriggerTraining(personId);
+
+        verify(spy).triggerSenderTraining(personId, 100);
+    }
+
+    @Test
+    void checkAndTriggerTraining_doesNotCallTrigger_whenQueued() {
+        when(blockRepository.countManualKurrentBlocksByPerson(personId)).thenReturn(100L);
+        when(senderModelRepository.findByPersonId(personId)).thenReturn(Optional.empty());
+
+        SenderModelService spy = spy(service);
+        doReturn(false).when(spy).runOrQueueSenderTraining(personId, 100);
+
+        spy.checkAndTriggerTraining(personId);
+
+        verify(spy, never()).triggerSenderTraining(any(), anyInt());
+    }
+
+    // ─── runOrQueueSenderTraining ─────────────────────────────────────────────
+
+    @Test
+    void runOrQueueSenderTraining_returnsTrue_whenIdle() {
+        when(trainingRunRepository.existsByPersonIdAndStatus(personId, TrainingStatus.QUEUED)).thenReturn(false);
+        when(trainingRunRepository.findFirstByStatus(TrainingStatus.RUNNING)).thenReturn(Optional.empty());
+
+        boolean result = service.runOrQueueSenderTraining(personId, 120);
+
+        assertThat(result).isTrue();
+        verify(trainingRunRepository, never()).save(argThat(r -> r.getStatus() == TrainingStatus.QUEUED));
+    }
+
+    @Test
+    void runOrQueueSenderTraining_savesQueued_whenRunning() {
+        when(trainingRunRepository.existsByPersonIdAndStatus(personId, TrainingStatus.QUEUED)).thenReturn(false);
+        when(trainingRunRepository.findFirstByStatus(TrainingStatus.RUNNING)).thenReturn(
+                Optional.of(OcrTrainingRun.builder().id(UUID.randomUUID()).status(TrainingStatus.RUNNING)
+                        .blockCount(5).documentCount(1).modelName("german_kurrent").build()));
+        when(blockRepository.countManualKurrentBlocksByPerson(personId)).thenReturn(120L);
+        when(trainingRunRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+
+        boolean result = service.runOrQueueSenderTraining(personId, 120);
+
+        assertThat(result).isFalse();
+        verify(trainingRunRepository).save(argThat(r ->
+                r.getStatus() == TrainingStatus.QUEUED && personId.equals(r.getPersonId())));
+    }
+
+    @Test
+    void runOrQueueSenderTraining_returnsFalse_whenAlreadyQueued() {
+        when(trainingRunRepository.existsByPersonIdAndStatus(personId, TrainingStatus.QUEUED)).thenReturn(true);
+
+        boolean result = service.runOrQueueSenderTraining(personId, 120);
+
+        assertThat(result).isFalse();
+        verify(trainingRunRepository, never()).save(any());
+    }
+
+    @Test
+    void runOrQueueSenderTraining_createsRunningRow_atomically() {
+        // RUNNING row must be created inside the same @Transactional boundary as the idle check,
+        // eliminating the race window between the check and a separate triggerSenderTraining call.
+        when(trainingRunRepository.existsByPersonIdAndStatus(personId, TrainingStatus.QUEUED)).thenReturn(false);
+        when(trainingRunRepository.findFirstByStatus(TrainingStatus.RUNNING)).thenReturn(Optional.empty());
+        when(blockRepository.countManualKurrentBlocksByPerson(personId)).thenReturn(120L);
+        when(trainingRunRepository.save(any())).thenAnswer(inv -> {
+            OcrTrainingRun r = inv.getArgument(0);
+            if (r.getId() == null) r.setId(UUID.randomUUID());
+            return r;
+        });
+
+        boolean result = service.runOrQueueSenderTraining(personId, 120);
+
+        assertThat(result).isTrue();
+        verify(trainingRunRepository).save(argThat(r ->
+                r.getStatus() == TrainingStatus.RUNNING && personId.equals(r.getPersonId())));
+    }
+
+    // ─── triggerSenderTraining — happy path ──────────────────────────────────
+
+    @Test
+    void triggerSenderTraining_savesModelRecord_onSuccess() throws Exception {
+        OcrTrainingRun runningRun = OcrTrainingRun.builder()
+                .id(UUID.randomUUID()).status(TrainingStatus.RUNNING)
+                .personId(personId).blockCount(10).documentCount(0)
+                .modelName("sender_" + personId).build();
+        when(trainingRunRepository.findFirstByPersonIdAndStatus(personId, TrainingStatus.RUNNING))
+                .thenReturn(Optional.of(runningRun));
+        when(trainingDataExportService.exportForSender(personId)).thenReturn(out -> {});
+        when(ocrClient.trainSenderModel(any(), any()))
+                .thenReturn(new OcrClient.TrainingResult(0.08, 0.92, 0.08, 5));
+        when(senderModelRepository.findByPersonId(personId)).thenReturn(Optional.empty());
+        when(senderModelRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+        when(trainingRunRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+        when(trainingRunRepository.findFirstByStatusOrderByCreatedAtAsc(TrainingStatus.QUEUED))
+                .thenReturn(Optional.empty());
+
+        service.triggerSenderTraining(personId, 120);
+
+        verify(senderModelRepository).save(argThat(m ->
+                ("/app/models/sender_" + personId + ".mlmodel").equals(m.getModelPath())
+                        && Double.valueOf(0.08).equals(m.getCer())
+                        && personId.equals(m.getPersonId())));
+        verify(trainingRunRepository, atLeastOnce()).save(argThat(r ->
+                r.getStatus() == TrainingStatus.DONE
+                        && Double.valueOf(0.08).equals(r.getCer())
+                        && r.getCompletedAt() != null));
+    }
+
+    // ─── triggerSenderTraining — failure path ────────────────────────────────
+
+    @Test
+    void triggerSenderTraining_marksRunFailed_whenOcrClientThrows() throws Exception {
+        OcrTrainingRun runningRun = OcrTrainingRun.builder()
+                .id(UUID.randomUUID()).status(TrainingStatus.RUNNING)
+                .personId(personId).blockCount(10).documentCount(0)
+                .modelName("sender_" + personId).build();
+        when(trainingRunRepository.findFirstByPersonIdAndStatus(personId, TrainingStatus.RUNNING))
+                .thenReturn(Optional.of(runningRun));
+        when(trainingDataExportService.exportForSender(personId)).thenReturn(out -> {});
+        when(ocrClient.trainSenderModel(any(), any()))
+                .thenThrow(new RuntimeException("OCR service timeout"));
+        when(trainingRunRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+        when(trainingRunRepository.findFirstByStatusOrderByCreatedAtAsc(TrainingStatus.QUEUED))
+                .thenReturn(Optional.empty());
+
+        service.triggerSenderTraining(personId, 120);
+
+        verify(trainingRunRepository, atLeastOnce()).save(argThat(r ->
+                r.getStatus() == TrainingStatus.FAILED
+                        && r.getErrorMessage() != null
+                        && r.getCompletedAt() != null));
+        verify(senderModelRepository, never()).save(any());
+    }
+
+    // ─── triggerSenderTraining — queue promotion ──────────────────────────────
+
+    @Test
+    void triggerSenderTraining_promotesNextQueued_afterCompletion() throws Exception {
+        UUID nextPersonId = UUID.randomUUID();
+
+        OcrTrainingRun runningRun = OcrTrainingRun.builder()
+                .id(UUID.randomUUID()).status(TrainingStatus.RUNNING)
+                .personId(personId).blockCount(10).documentCount(0)
+                .modelName("sender_" + personId).build();
+        when(trainingRunRepository.findFirstByPersonIdAndStatus(personId, TrainingStatus.RUNNING))
+                .thenReturn(Optional.of(runningRun));
+        when(trainingRunRepository.save(any())).thenAnswer(inv -> {
+            OcrTrainingRun r = inv.getArgument(0);
+            if (r.getId() == null) r.setId(UUID.randomUUID());
+            return r;
+        });
+        when(trainingDataExportService.exportForSender(personId)).thenReturn(out -> {});
+        when(ocrClient.trainSenderModel(any(), any()))
+                .thenReturn(new OcrClient.TrainingResult(0.05, 0.95, 0.05, 3));
+        when(senderModelRepository.findByPersonId(personId)).thenReturn(Optional.empty());
+
+        OcrTrainingRun queued = OcrTrainingRun.builder()
+                .id(UUID.randomUUID()).status(TrainingStatus.QUEUED)
+                .personId(nextPersonId).blockCount(5).documentCount(0)
+                .modelName("sender_" + nextPersonId).build();
+        when(trainingRunRepository.findFirstByStatusOrderByCreatedAtAsc(TrainingStatus.QUEUED))
+                .thenReturn(Optional.of(queued));
+        when(blockRepository.countManualKurrentBlocksByPerson(nextPersonId)).thenReturn(5L);
+
+        SenderModelService spy = spy(service);
+        // Stub the recursive call to stop the chain after one promotion
+        doNothing().when(spy).triggerSenderTraining(eq(nextPersonId), anyInt());
+
+        spy.triggerSenderTraining(personId, 10);
+
+        // Queued run promoted to RUNNING
+        verify(trainingRunRepository).save(argThat(r ->
+                nextPersonId.equals(r.getPersonId()) && r.getStatus() == TrainingStatus.RUNNING));
+        // Next training was kicked off
+        verify(spy).triggerSenderTraining(eq(nextPersonId), anyInt());
+    }
+}

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

@@ -22,6 +22,7 @@ class TranscriptionServiceGuidedTest {
     AnnotationRepository annotationRepository;
     AnnotationService annotationService;
     DocumentService documentService;
+    SenderModelService senderModelService;
     TranscriptionService service;
 
     UUID docId = UUID.randomUUID();
@@ -35,9 +36,10 @@ class TranscriptionServiceGuidedTest {
         annotationRepository = mock(AnnotationRepository.class);
         annotationService = mock(AnnotationService.class);
         documentService = mock(DocumentService.class);
+        senderModelService = mock(SenderModelService.class);
 
         service = new TranscriptionService(blockRepository, versionRepository,
-                annotationRepository, annotationService, documentService);
+                annotationRepository, annotationService, documentService, senderModelService);
 
         when(blockRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
         when(versionRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));

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

@@ -13,6 +13,8 @@ import org.raddatz.familienarchiv.exception.DomainException;
 import org.raddatz.familienarchiv.model.BlockSource;
 import org.raddatz.familienarchiv.model.Document;
 import org.raddatz.familienarchiv.model.DocumentAnnotation;
+import org.raddatz.familienarchiv.model.Person;
+import org.raddatz.familienarchiv.model.ScriptType;
 import org.raddatz.familienarchiv.model.TranscriptionBlock;
 import org.raddatz.familienarchiv.model.TranscriptionBlockVersion;
 import org.raddatz.familienarchiv.repository.AnnotationRepository;
@@ -39,6 +41,7 @@ class TranscriptionServiceTest {
     @Mock AnnotationRepository annotationRepository;
     @Mock AnnotationService annotationService;
     @Mock DocumentService documentService;
+    @Mock SenderModelService senderModelService;
     @InjectMocks TranscriptionService transcriptionService;
 
     // ─── getBlock ────────────────────────────────────────────────────────────────
@@ -156,6 +159,8 @@ class TranscriptionServiceTest {
                 .id(blockId).documentId(docId).text("old").build();
         when(blockRepository.findByIdAndDocumentId(blockId, docId)).thenReturn(Optional.of(block));
         when(blockRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+        when(documentService.getDocumentById(any())).thenReturn(
+                Document.builder().scriptType(ScriptType.TYPEWRITER).build());
 
         UpdateTranscriptionBlockDTO dto = new UpdateTranscriptionBlockDTO("new text", null);
 
@@ -175,6 +180,8 @@ class TranscriptionServiceTest {
                 .id(blockId).documentId(docId).text("text").label("old label").build();
         when(blockRepository.findByIdAndDocumentId(blockId, docId)).thenReturn(Optional.of(block));
         when(blockRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+        when(documentService.getDocumentById(any())).thenReturn(
+                Document.builder().scriptType(ScriptType.TYPEWRITER).build());
 
         UpdateTranscriptionBlockDTO dto = new UpdateTranscriptionBlockDTO("text", "Anrede");
 
@@ -183,6 +190,57 @@ class TranscriptionServiceTest {
         assertThat(result.getLabel()).isEqualTo("Anrede");
     }
 
+    @Test
+    void updateBlock_setsSourceToManual() {
+        UUID docId = UUID.randomUUID();
+        UUID blockId = UUID.randomUUID();
+        TranscriptionBlock block = TranscriptionBlock.builder()
+                .id(blockId).documentId(docId).text("old").source(BlockSource.OCR).build();
+        when(blockRepository.findByIdAndDocumentId(blockId, docId)).thenReturn(Optional.of(block));
+        when(blockRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+        when(documentService.getDocumentById(any())).thenReturn(
+                Document.builder().scriptType(ScriptType.TYPEWRITER).build());
+
+        TranscriptionBlock result = transcriptionService.updateBlock(
+                docId, blockId, new UpdateTranscriptionBlockDTO("new", null), UUID.randomUUID());
+
+        assertThat(result.getSource()).isEqualTo(BlockSource.MANUAL);
+    }
+
+    @Test
+    void updateBlock_triggersTraining_whenKurrentSenderPresent() {
+        UUID docId = UUID.randomUUID();
+        UUID blockId = UUID.randomUUID();
+        UUID senderId = UUID.randomUUID();
+        Person sender = Person.builder().id(senderId).build();
+        TranscriptionBlock block = TranscriptionBlock.builder()
+                .id(blockId).documentId(docId).text("old").build();
+        when(blockRepository.findByIdAndDocumentId(blockId, docId)).thenReturn(Optional.of(block));
+        when(blockRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+        when(documentService.getDocumentById(any())).thenReturn(
+                Document.builder().scriptType(ScriptType.HANDWRITING_KURRENT).sender(sender).build());
+
+        transcriptionService.updateBlock(docId, blockId, new UpdateTranscriptionBlockDTO("text", null), UUID.randomUUID());
+
+        verify(senderModelService).checkAndTriggerTraining(senderId);
+    }
+
+    @Test
+    void updateBlock_doesNotTriggerTraining_whenNoSender() {
+        UUID docId = UUID.randomUUID();
+        UUID blockId = UUID.randomUUID();
+        TranscriptionBlock block = TranscriptionBlock.builder()
+                .id(blockId).documentId(docId).text("old").build();
+        when(blockRepository.findByIdAndDocumentId(blockId, docId)).thenReturn(Optional.of(block));
+        when(blockRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+        when(documentService.getDocumentById(any())).thenReturn(
+                Document.builder().scriptType(ScriptType.HANDWRITING_KURRENT).build());
+
+        transcriptionService.updateBlock(docId, blockId, new UpdateTranscriptionBlockDTO("text", null), UUID.randomUUID());
+
+        verify(senderModelService, never()).checkAndTriggerTraining(any());
+    }
+
     // ─── deleteBlock ─────────────────────────────────────────────────────────────
 
     @Test

docker-compose.yml

@@ -97,6 +97,7 @@ services:
       DETECTOR_BATCH_SIZE: "8"
       OCR_CLAHE_CLIP_LIMIT: "2.0"   # CLAHE contrast limit (multiplier of average histogram frequency)
       OCR_CLAHE_TILE_SIZE: "8"      # CLAHE tile grid size (NxN tiles per page)
+      OCR_MAX_CACHED_MODELS: "2"    # LRU cache; each model ~500 MB, so 2 = ~1 GB resident
     networks:
       - archive-net
     healthcheck:

frontend/messages/de.json

@@ -330,6 +330,7 @@
 	"comment_time_days": "vor {count} Tag(en)",
 	"comment_panel_title": "Kommentare",
 	"comment_panel_close": "Schließen",
+	"comp_dismiss": "Schließen",
 	"doc_panel_tab_metadata": "Metadaten",
 	"doc_panel_tab_transcription": "Transkription",
 	"doc_panel_tab_discussion": "Diskussion",
@@ -541,6 +542,7 @@
 	"training_start_btn": "Training starten",
 	"training_in_progress": "…",
 	"training_success": "Training wurde gestartet und abgeschlossen.",
+	"training_start_failed": "Training konnte nicht gestartet werden. Bitte versuche es erneut.",
 	"training_too_few_blocks": "Mindestens 5 geprüfte Blöcke erforderlich (aktuell: {available}).",
 	"training_service_down": "OCR-Dienst ist nicht erreichbar.",
 	"training_history_heading": "Verlauf",
@@ -561,6 +563,11 @@
 	"transcription_block_segmentation_only": "Nur Segmentierung",
 	"training_chip_kurrent": "Kurrent-Erkennung",
 	"training_chip_segmentation": "Segmentierung",
+	"training_col_type": "Typ",
+	"training_type_base": "Basis",
+	"training_type_personalized": "Personalisiert",
+	"training_col_person": "Absender",
+	"training_status_queued": "Warteschlange",
 	"mission_control_heading": "Was braucht Aufmerksamkeit?",
 	"mission_control_segmentation_heading": "Text markieren",
 	"mission_control_segmentation_description": "Textbereiche markieren — keine Vorkenntnisse nötig",

frontend/messages/en.json

@@ -330,6 +330,7 @@
 	"comment_time_days": "{count} day(s) ago",
 	"comment_panel_title": "Comments",
 	"comment_panel_close": "Close",
+	"comp_dismiss": "Dismiss",
 	"doc_panel_tab_metadata": "Metadata",
 	"doc_panel_tab_transcription": "Transcription",
 	"doc_panel_tab_discussion": "Discussion",
@@ -541,6 +542,7 @@
 	"training_start_btn": "Start training",
 	"training_in_progress": "…",
 	"training_success": "Training started and completed.",
+	"training_start_failed": "Failed to start training. Please try again.",
 	"training_too_few_blocks": "At least 5 reviewed blocks required (currently: {available}).",
 	"training_service_down": "OCR service is unavailable.",
 	"training_history_heading": "History",
@@ -561,6 +563,11 @@
 	"transcription_block_segmentation_only": "Segmentation only",
 	"training_chip_kurrent": "Kurrent recognition",
 	"training_chip_segmentation": "Segmentation",
+	"training_col_type": "Type",
+	"training_type_base": "Base",
+	"training_type_personalized": "Personalized",
+	"training_col_person": "Sender",
+	"training_status_queued": "Queued",
 	"mission_control_heading": "What needs attention?",
 	"mission_control_segmentation_heading": "Mark text",
 	"mission_control_segmentation_description": "Mark text areas — no prior knowledge needed",

frontend/messages/es.json

@@ -330,6 +330,7 @@
 	"comment_time_days": "hace {count} día(s)",
 	"comment_panel_title": "Comentarios",
 	"comment_panel_close": "Cerrar",
+	"comp_dismiss": "Cerrar",
 	"doc_panel_tab_metadata": "Metadatos",
 	"doc_panel_tab_transcription": "Transcripción",
 	"doc_panel_tab_discussion": "Discusión",
@@ -541,6 +542,7 @@
 	"training_start_btn": "Iniciar entrenamiento",
 	"training_in_progress": "…",
 	"training_success": "Entrenamiento iniciado y completado.",
+	"training_start_failed": "No se pudo iniciar el entrenamiento. Por favor, inténtalo de nuevo.",
 	"training_too_few_blocks": "Se requieren al menos 5 bloques revisados (actualmente: {available}).",
 	"training_service_down": "El servicio OCR no está disponible.",
 	"training_history_heading": "Historial",
@@ -561,6 +563,11 @@
 	"transcription_block_segmentation_only": "Solo segmentación",
 	"training_chip_kurrent": "Reconocimiento Kurrent",
 	"training_chip_segmentation": "Segmentación",
+	"training_col_type": "Tipo",
+	"training_type_base": "Base",
+	"training_type_personalized": "Personalizado",
+	"training_col_person": "Remitente",
+	"training_status_queued": "En cola",
 	"mission_control_heading": "¿Qué necesita atención?",
 	"mission_control_segmentation_heading": "Marcar texto",
 	"mission_control_segmentation_description": "Marcar áreas de texto — sin conocimientos previos",

frontend/src/lib/components/OcrTrainingCard.svelte

@@ -1,26 +1,16 @@
 <script lang="ts">
 import TrainingHistory from './TrainingHistory.svelte';
 import { m } from '$lib/paraglide/messages.js';
-
+import type { TrainingRun } from '$lib/types/training.js';
-interface Run {
-	id: string;
-	status: 'RUNNING' | 'DONE' | 'FAILED';
-	blockCount: number;
-	documentCount: number;
-	modelName: string;
-	errorMessage?: string;
-	triggeredBy?: string;
-	createdAt: string;
-	completedAt?: string;
-}
 
 interface TrainingInfo {
 	availableBlocks?: number;
 	totalOcrBlocks?: number;
 	availableDocuments?: number;
 	ocrServiceAvailable?: boolean;
-	lastRun?: Run | null;
+	lastRun?: TrainingRun | null;
-	runs?: Run[];
+	runs?: TrainingRun[];
+	personNames?: Record<string, string>;
 }
 
 interface Props {
@@ -31,6 +21,7 @@ let { trainingInfo }: Props = $props();
 
 let training = $state(false);
 let successMessage = $state<string | null>(null);
+let errorMessage = $state<string | null>(null);
 
 const available = $derived(trainingInfo?.availableBlocks ?? 0);
 const tooFewBlocks = $derived(available < 5);
@@ -40,6 +31,7 @@ const disabled = $derived(training || tooFewBlocks || serviceDown);
 async function startTraining() {
 	training = true;
 	successMessage = null;
+	errorMessage = null;
 	try {
 		const res = await fetch('/api/ocr/train', { method: 'POST' });
 		if (res.ok) {
@@ -47,7 +39,11 @@ async function startTraining() {
 			setTimeout(() => {
 				successMessage = null;
 			}, 5000);
+		} else {
+			errorMessage = m.training_start_failed();
 		}
+	} catch {
+		errorMessage = m.training_start_failed();
 	} finally {
 		training = false;
 	}
@@ -82,11 +78,26 @@ async function startTraining() {
 	{/if}
 
 	{#if successMessage}
-		<p class="mt-2 text-xs text-green-700">{successMessage}</p>
+		<p class="mt-2 flex items-center gap-2 text-xs text-green-700" aria-live="polite">
+			{successMessage}
+			<button
+				type="button"
+				class="-my-2 ml-1 inline-flex h-11 w-11 items-center justify-center rounded-sm underline hover:no-underline focus-visible:ring-2 focus-visible:ring-brand-navy focus-visible:outline-none"
+				onclick={() => (successMessage = null)}
+				aria-label={m.comp_dismiss()}>×</button
+			>
+		</p>
+	{/if}
+
+	{#if errorMessage}
+		<p class="mt-2 text-xs text-red-600" aria-live="assertive">{errorMessage}</p>
 	{/if}
 
 	<h3 class="mt-6 mb-3 text-xs font-bold tracking-widest text-ink-3 uppercase">
 		{m.training_history_heading()}
 	</h3>
-	<TrainingHistory runs={(trainingInfo?.runs ?? []).filter((r) => r.modelName !== 'blla')} />
+	<TrainingHistory
+		runs={(trainingInfo?.runs ?? []).filter((r) => r.modelName !== 'blla')}
+		personNames={trainingInfo?.personNames ?? {}}
+	/>
 </div>

frontend/src/lib/components/OcrTrainingCard.svelte.spec.ts

@@ -73,6 +73,24 @@ describe('OcrTrainingCard — enabled state', () => {
 	});
 });
 
+describe('OcrTrainingCard — success dismiss button', () => {
+	it('dismiss button has 44×44px touch target (h-11 w-11)', async () => {
+		vi.stubGlobal('fetch', vi.fn().mockResolvedValue({ ok: true }));
+
+		render(OcrTrainingCard, { trainingInfo: baseInfo });
+
+		const btn = page.getByRole('button', { name: /Training starten/i });
+		await btn.click();
+
+		const dismissBtn = page.getByRole('button', { name: /Schließen/i });
+		await expect.element(dismissBtn).toBeInTheDocument();
+
+		const el = await dismissBtn.element();
+		expect(el.classList.contains('h-11')).toBe(true);
+		expect(el.classList.contains('w-11')).toBe(true);
+	});
+});
+
 describe('OcrTrainingCard — in-flight state', () => {
 	it('shows "…" while POST is in-flight', async () => {
 		let resolveFetch!: (v: unknown) => void;

frontend/src/lib/components/TrainingHistory.svelte

@@ -1,24 +1,13 @@
 <script lang="ts">
 import { m } from '$lib/paraglide/messages.js';
-
+import type { TrainingRun } from '$lib/types/training.js';
-interface Run {
-	id: string;
-	status: 'RUNNING' | 'DONE' | 'FAILED';
-	blockCount: number;
-	documentCount: number;
-	modelName: string;
-	errorMessage?: string;
-	triggeredBy?: string;
-	createdAt: string;
-	completedAt?: string;
-	cer?: number;
-}
 
 interface Props {
-	runs: Run[];
+	runs: TrainingRun[];
+	personNames?: Record<string, string>;
 }
 
-let { runs }: Props = $props();
+let { runs, personNames }: Props = $props();
 
 const COLLAPSED_COUNT = 3;
 let expanded = $state(false);
@@ -47,6 +36,8 @@ function formatCer(cer: number | undefined | null): string {
 		<tr class="border-b border-line text-xs font-bold tracking-widest text-ink-3 uppercase">
 			<th class="pb-2 text-left">{m.training_history_col_date()}</th>
 			<th class="pb-2 text-left">{m.training_history_col_status()}</th>
+			<th class="hidden pb-2 text-left md:table-cell">{m.training_col_type()}</th>
+			<th class="hidden pb-2 text-left md:table-cell">{m.training_col_person()}</th>
 			<th class="pb-2 text-right">{m.training_history_col_blocks()}</th>
 			<th class="hidden pb-2 text-right md:table-cell">{m.training_history_col_docs()}</th>
 			<th class="hidden pb-2 text-right md:table-cell">{m.training_history_col_cer()}</th>
@@ -55,7 +46,7 @@ function formatCer(cer: number | undefined | null): string {
 	<tbody id="training-history-rows">
 		{#if runs.length === 0}
 			<tr>
-				<td colspan="5" class="py-4 text-center text-sm text-ink-2">
+				<td colspan="7" class="py-4 text-center text-sm text-ink-2">
 					{m.training_history_empty()}
 				</td>
 			</tr>
@@ -64,7 +55,14 @@ function formatCer(cer: number | undefined | null): string {
 				<tr class="border-b border-line/50 last:border-0">
 					<td class="py-2 text-ink-2">{formatDate(run.createdAt)}</td>
 					<td class="py-2">
-						{#if run.status === 'DONE'}
+						{#if run.status === 'QUEUED'}
+							<span
+								class="inline-flex items-center gap-1 rounded-sm bg-amber-100 px-1.5 py-0.5 text-xs font-medium text-amber-700"
+							>
+								<span aria-hidden="true" class="h-1.5 w-1.5 rounded-full bg-amber-500"></span>
+								{m.training_status_queued()}
+							</span>
+						{:else if run.status === 'DONE'}
 							<span
 								class="inline-flex items-center gap-1 rounded-sm bg-green-100 px-1.5 py-0.5 text-xs font-medium text-green-700"
 							>
@@ -119,6 +117,17 @@ function formatCer(cer: number | undefined | null): string {
 								{m.training_status_running()}
 							</span>
 						{/if}
+						{#if run.personId && personNames?.[run.personId]}
+							<span class="mt-0.5 block text-xs text-ink-3 md:hidden"
+								>{personNames[run.personId]}</span
+							>
+						{/if}
+					</td>
+					<td class="hidden py-2 text-left text-ink-2 md:table-cell">
+						{run.personId ? m.training_type_personalized() : m.training_type_base()}
+					</td>
+					<td class="hidden py-2 text-left text-ink-2 md:table-cell">
+						{run.personId && personNames?.[run.personId] ? personNames[run.personId] : '—'}
 					</td>
 					<td class="py-2 text-right text-ink-2">{run.blockCount}</td>
 					<td class="hidden py-2 text-right text-ink-2 md:table-cell">{run.documentCount}</td>
@@ -137,7 +146,7 @@ function formatCer(cer: number | undefined | null): string {
 			type="button"
 			aria-expanded={expanded}
 			aria-controls="training-history-rows"
-			class="text-xs font-medium text-ink-3 transition-colors hover:text-ink"
+			class="rounded-sm py-2 text-xs font-medium text-ink-3 transition-colors hover:text-ink focus-visible:ring-2 focus-visible:ring-brand-navy focus-visible:ring-offset-1 focus-visible:outline-none"
 			onclick={() => (expanded = !expanded)}
 		>
 			{expanded ? m.comp_expandable_show_less() : m.comp_expandable_show_more()}

frontend/src/lib/components/TrainingHistory.svelte.spec.ts

@@ -50,3 +50,36 @@ describe('TrainingHistory — expand/collapse', () => {
 			.not.toBeInTheDocument();
 	});
 });
+
+describe('TrainingHistory — status badges', () => {
+	it('shows amber QUEUED badge for queued runs', async () => {
+		const run = { ...makeRun(0), status: 'QUEUED' as const };
+		render(TrainingHistory, { runs: [run] });
+
+		await expect.element(page.getByText(/Warteschlange/i)).toBeInTheDocument();
+	});
+});
+
+describe('TrainingHistory — type and person columns', () => {
+	it('shows "Basis" for runs without personId', async () => {
+		render(TrainingHistory, { runs: [makeRun(0)] });
+
+		await expect.element(page.getByText(/Basis/i)).toBeInTheDocument();
+	});
+
+	it('shows "Personalisiert" for runs with personId', async () => {
+		const run = { ...makeRun(0), personId: 'person-1' };
+		render(TrainingHistory, { runs: [run], personNames: { 'person-1': 'Karl Müller' } });
+
+		await expect.element(page.getByText(/Personalisiert/i)).toBeInTheDocument();
+	});
+
+	it('shows person name from personNames for sender runs', async () => {
+		const run = { ...makeRun(0), personId: 'person-1' };
+		render(TrainingHistory, { runs: [run], personNames: { 'person-1': 'Karl Müller' } });
+
+		await expect.element(page.getByText(/Personalisiert/i)).toBeInTheDocument();
+		// Name appears in both the mobile inline span and the desktop table cell
+		await expect.element(page.getByText('Karl Müller').first()).toBeInTheDocument();
+	});
+});

frontend/src/lib/generated/api.ts

@@ -1374,7 +1374,7 @@ export interface components {
         };
         MergeTagDTO: {
             /** Format: uuid */
-            targetId?: string;
+            targetId: string;
         };
         PersonNameAliasDTO: {
             lastName: string;
@@ -1398,7 +1398,7 @@ export interface components {
             /** Format: uuid */
             id: string;
             /** @enum {string} */
-            status: "RUNNING" | "DONE" | "FAILED";
+            status: "QUEUED" | "RUNNING" | "DONE" | "FAILED";
             /** Format: int32 */
             blockCount: number;
             /** Format: int32 */
@@ -1415,6 +1415,8 @@ export interface components {
             errorMessage?: string;
             /** Format: uuid */
             triggeredBy?: string;
+            /** Format: uuid */
+            personId?: string;
             /** Format: date-time */
             createdAt: string;
             /** Format: date-time */
@@ -1596,11 +1598,11 @@ export interface components {
         };
         TagTreeNodeDTO: {
             /** Format: uuid */
-            id?: string;
+            id: string;
-            name?: string;
+            name: string;
             color?: string;
             /** Format: int32 */
-            documentCount?: number;
+            documentCount: number;
             children?: components["schemas"]["TagTreeNodeDTO"][];
             /**
              * Format: uuid
@@ -1619,7 +1621,6 @@ export interface components {
             /** Format: uuid */
             id?: string;
             displayName?: string;
-            personType?: string;
             firstName?: string;
             lastName?: string;
             /** Format: int64 */
@@ -1630,19 +1631,7 @@ export interface components {
             deathYear?: number;
             alias?: string;
             notes?: string;
-        };
+            personType?: string;
-        TrainingInfoResponse: {
-            /** Format: int32 */
-            availableBlocks?: number;
-            /** Format: int32 */
-            totalOcrBlocks?: number;
-            /** Format: int32 */
-            availableDocuments?: number;
-            /** Format: int32 */
-            availableSegBlocks?: number;
-            ocrServiceAvailable?: boolean;
-            lastRun?: components["schemas"]["OcrTrainingRun"];
-            runs?: components["schemas"]["OcrTrainingRun"][];
         };
         StreamingResponseBody: unknown;
         OcrJob: {
@@ -1671,13 +1660,11 @@ export interface components {
             timeout?: number;
         };
         PageNotificationDTO: {
-            /** Format: int64 */
-            totalElements?: number;
             /** Format: int32 */
             totalPages?: number;
+            /** Format: int64 */
+            totalElements?: number;
             pageable?: components["schemas"]["PageableObject"];
-            first?: boolean;
-            last?: boolean;
             /** Format: int32 */
             size?: number;
             content?: components["schemas"]["NotificationDTO"][];
@@ -1686,6 +1673,8 @@ export interface components {
             sort?: components["schemas"]["SortObject"];
             /** Format: int32 */
             numberOfElements?: number;
+            first?: boolean;
+            last?: boolean;
             empty?: boolean;
         };
         PageableObject: {
@@ -3501,7 +3490,9 @@ export interface operations {
                     [name: string]: unknown;
                 };
                 content: {
-                    "*/*": components["schemas"]["TrainingInfoResponse"];
+                    "*/*": {
+                        [key: string]: unknown;
+                    };
                 };
             };
         };

frontend/src/lib/types/training.ts

@@ -0,0 +1,13 @@
+export interface TrainingRun {
+	id: string;
+	status: 'QUEUED' | 'RUNNING' | 'DONE' | 'FAILED';
+	personId?: string;
+	blockCount: number;
+	documentCount: number;
+	modelName: string;
+	errorMessage?: string;
+	triggeredBy?: string;
+	createdAt: string;
+	completedAt?: string;
+	cer?: number;
+}

ocr-service/engines/kraken.py

@@ -1,13 +1,84 @@
 """Kraken OCR engine wrapper — historical HTR model support for Kurrent/Suetterlin."""
 
+from __future__ import annotations
+
+import collections
 import logging
 import os
+import threading
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from PIL.Image import Image
 
 logger = logging.getLogger(__name__)
 
 _model = None
 _model_path = os.environ.get("KRAKEN_MODEL_PATH", "/app/models/german_kurrent.mlmodel")
 
+_MODELS_DIR = os.path.realpath("/app/models")
+_MAX_CACHED_SENDER_MODELS = int(os.environ.get("OCR_MAX_CACHED_MODELS", "5"))
+
+
+def _load_sender_model(path: str):
+    """Load a Kraken model from disk. Extracted for testability."""
+    from kraken.lib import models as kraken_models
+    return kraken_models.load_any(path)
+
+
+class _SenderModelRegistry:
+    """Thread-safe LRU cache for per-sender Kraken models.
+
+    Uses double-checked locking: model loading happens outside the lock to
+    avoid blocking concurrent OCR requests. At most one entry per path is
+    stored even under concurrent load.
+    """
+
+    def __init__(self, max_size: int):
+        self._max_size = max_size
+        self._cache: collections.OrderedDict = collections.OrderedDict()
+        self._lock = threading.Lock()
+
+    def get_model(self, model_path: str):
+        """Return the cached model or load it. Validates path is within /app/models/."""
+        resolved = os.path.realpath(model_path)
+        if not resolved.startswith(_MODELS_DIR + os.sep) and resolved != _MODELS_DIR:
+            raise ValueError(f"Sender model path not allowed: {model_path}")
+
+        with self._lock:
+            if model_path in self._cache:
+                self._cache.move_to_end(model_path)
+                return self._cache[model_path]
+
+        new_model = _load_sender_model(model_path)
+
+        with self._lock:
+            if model_path in self._cache:
+                self._cache.move_to_end(model_path)
+                return self._cache[model_path]
+            self._cache[model_path] = new_model
+            self._cache.move_to_end(model_path)
+            while len(self._cache) > self._max_size:
+                self._cache.popitem(last=False)
+
+        return new_model
+
+    def invalidate(self, model_path: str) -> None:
+        """Remove model from cache so the next request reloads from disk."""
+        with self._lock:
+            self._cache.pop(model_path, None)
+
+    def size(self) -> int:
+        with self._lock:
+            return len(self._cache)
+
+    def _contains(self, model_path: str) -> bool:
+        with self._lock:
+            return model_path in self._cache
+
+
+_sender_registry = _SenderModelRegistry(_MAX_CACHED_SENDER_MODELS)
+
 
 def load_models():
     """Load the Kraken model at startup. Skips if model file is not present."""
@@ -29,10 +100,12 @@ def is_available() -> bool:
     return _model is not None
 
 
-def extract_page_blocks(image, page_idx: int, language: str = "de") -> list[dict]:
+def extract_page_blocks(image: Image, page_idx: int, language: str = "de",
+                         sender_model_path: str | None = None) -> list[dict]:
     """Run Kraken segmentation + recognition on a single PIL image.
 
     Returns block dicts for that page. Coordinates are normalized to [0, 1].
+    When sender_model_path is provided, the per-sender fine-tuned model is used.
     """
     from kraken import blla, rpred
     from confidence import words_from_characters
@@ -40,11 +113,13 @@ def extract_page_blocks(image, page_idx: int, language: str = "de") -> list[dict
     if _model is None:
         raise RuntimeError("Kraken model is not loaded")
 
+    active_model = _sender_registry.get_model(sender_model_path) if sender_model_path else _model
+
     page_w, page_h = image.size
     blocks = []
 
     baseline_seg = blla.segment(image)
-    pred_it = rpred.rpred(_model, image, baseline_seg)
+    pred_it = rpred.rpred(active_model, image, baseline_seg)
 
     for record in pred_it:
         polygon_pts = record.boundary if hasattr(record, "boundary") and record.boundary else []
@@ -79,13 +154,15 @@ def extract_page_blocks(image, page_idx: int, language: str = "de") -> list[dict
     return blocks
 
 
-def extract_region_text(image, x: float, y: float, w: float, h: float) -> str:
+def extract_region_text(image: Image, x: float, y: float, w: float, h: float,
+                         sender_model_path: str | None = None) -> str:
     """Crop image to a normalized region and run Kraken recognition on the crop.
 
     Used for guided OCR — skips full-page layout detection entirely.
     A single synthetic baseline spanning the full crop width is used so that
     blla.segment() (which crashes on small crops) is never called.
     Coordinates are normalized to [0, 1].
+    When sender_model_path is provided, the per-sender fine-tuned model is used.
     """
     from kraken import rpred
     from kraken.containers import Segmentation, BaselineLine
@@ -93,6 +170,8 @@ def extract_region_text(image, x: float, y: float, w: float, h: float) -> str:
     if _model is None:
         raise RuntimeError("Kraken model is not loaded")
 
+    active_model = _sender_registry.get_model(sender_model_path) if sender_model_path else _model
+
     pw, ph = image.size
     x1 = max(0, int(x * pw))
     y1 = max(0, int(y * ph))
@@ -123,11 +202,12 @@ def extract_region_text(image, x: float, y: float, w: float, h: float) -> str:
         regions={},
         line_orders=[],
     )
-    pred_it = rpred.rpred(_model, crop, synthetic_seg)
+    pred_it = rpred.rpred(active_model, crop, synthetic_seg)
     return " ".join(r.prediction for r in pred_it)
 
 
-def extract_blocks(images: list, language: str = "de") -> list[dict]:
+def extract_blocks(images: list, language: str = "de",
+                   sender_model_path: str | None = None) -> list[dict]:
     """Run Kraken segmentation + recognition on a list of PIL images.
 
     Returns block dicts with pageNumber, x, y, width, height, polygon, text.
@@ -137,7 +217,7 @@ def extract_blocks(images: list, language: str = "de") -> list[dict]:
     all_blocks = []
 
     for page_idx, image in enumerate(images, start=1):
-        all_blocks.extend(extract_page_blocks(image, page_idx, language))
+        all_blocks.extend(extract_page_blocks(image, page_idx, language, sender_model_path))
 
     return all_blocks
 

ocr-service/main.py

@@ -17,7 +17,7 @@ from urllib.parse import urlparse
 
 import httpx
 import pypdfium2 as pdfium
-from fastapi import FastAPI, Header, HTTPException, UploadFile
+from fastapi import FastAPI, Form, Header, HTTPException, UploadFile
 from fastapi.responses import StreamingResponse
 from PIL import Image
 
@@ -103,7 +103,8 @@ async def run_ocr(request: OcrRequest):
                 status_code=400,
                 detail="Kraken model not available — cannot process Kurrent script",
             )
-        blocks = await asyncio.to_thread(kraken_engine.extract_blocks, images, request.language)
+        blocks = await asyncio.to_thread(
+            kraken_engine.extract_blocks, images, request.language, request.senderModelPath)
     else:
         # TYPEWRITER, HANDWRITING_LATIN, UNKNOWN — all use Surya
         blocks = await asyncio.to_thread(surya_engine.extract_blocks, images, request.language)
@@ -171,10 +172,12 @@ async def run_ocr_stream(request: OcrRequest):
                     yield json.dumps({"type": "preprocessing", "pageNumber": page_idx}) + "\n"
                     image = await asyncio.to_thread(preprocess_page, image)
                     blocks = []
+                    sender_path = request.senderModelPath if use_kraken else None
                     for region in page_regions:
                         text = await asyncio.to_thread(
                             engine.extract_region_text, image,
                             region.x, region.y, region.width, region.height,
+                            sender_path,
                         )
                         if script_type in _SPELL_CHECK_SCRIPT_TYPES:
                             text = correct_text(text)
@@ -231,8 +234,9 @@ async def run_ocr_stream(request: OcrRequest):
             try:
                 yield json.dumps({"type": "preprocessing", "pageNumber": page_idx}) + "\n"
                 image = await asyncio.to_thread(preprocess_page, image)
+                sender_path = request.senderModelPath if use_kraken else None
                 blocks = await asyncio.to_thread(
-                    engine.extract_page_blocks, image, page_idx, request.language
+                    engine.extract_page_blocks, image, page_idx, request.language, sender_path
                 )
 
                 for block in blocks:
@@ -443,6 +447,86 @@ async def train_model(
     return result
 
 
+@app.post("/train-sender")
+async def train_sender_model(
+    file: UploadFile,
+    output_model_path: str = Form(...),
+    x_training_token: str | None = Header(default=None),
+):
+    """Fine-tune a per-sender Kurrent model and save to output_model_path.
+
+    output_model_path must be within /app/models/. The per-sender model cache
+    is invalidated after training so the next OCR request picks up the new model.
+    """
+    _check_training_token(x_training_token)
+
+    if not _models_ready:
+        raise HTTPException(status_code=503, detail="Models not loaded yet")
+
+    models_dir = os.path.realpath("/app/models")
+    resolved_output = os.path.realpath(output_model_path)
+    if not resolved_output.startswith(models_dir + os.sep):
+        raise HTTPException(status_code=400, detail="output_model_path must be within /app/models/")
+
+    zip_bytes = await file.read()
+
+    training_run_id = datetime.now(timezone.utc).strftime("%Y%m%dT%H%M%SZ")
+    log = logging.LoggerAdapter(logger, {"training_run_id": training_run_id})
+    log.info("Starting sender training run %s → %s", training_run_id, output_model_path)
+
+    def _run_sender_training() -> dict:
+        with tempfile.TemporaryDirectory() as tmp_dir:
+            with zipfile.ZipFile(io.BytesIO(zip_bytes)) as zf:
+                for entry in zf.namelist():
+                    _validate_zip_entry(entry, tmp_dir)
+                zf.extractall(tmp_dir)
+
+            ground_truth = glob.glob(os.path.join(tmp_dir, "*.xml"))
+            if not ground_truth:
+                raise HTTPException(status_code=422, detail="No ground-truth files found in ZIP")
+
+            log.info("Sender training on %d ground-truth pairs", len(ground_truth))
+            checkpoint_dir = os.path.join(tmp_dir, "checkpoints")
+            os.makedirs(checkpoint_dir, exist_ok=True)
+
+            cmd = [
+                "ketos", "--workers", "0", "--device", "cpu", "--threads", "2",
+                "train",
+                "-f", "page",
+                "--weights-format", "coreml",
+                "-o", checkpoint_dir,
+                "-q", "fixed",
+                "-N", "10",
+                "-B", "1",
+            ]
+            if os.path.exists(KRAKEN_MODEL_PATH):
+                cmd += ["-i", KRAKEN_MODEL_PATH]
+            cmd += ground_truth
+
+            log.info("Running sender training: %s", " ".join(cmd[:6]) + " ...")
+            proc = subprocess.run(cmd, capture_output=True, text=True)
+            if proc.returncode != 0:
+                raise RuntimeError(f"ketos train failed (exit {proc.returncode}): {proc.stderr[-500:]}")
+
+            accuracy, epochs = _parse_best_checkpoint(checkpoint_dir)
+            cer = round(1.0 - accuracy, 4) if accuracy is not None else None
+
+            best_model = _find_best_model(checkpoint_dir)
+            if best_model is None:
+                raise RuntimeError("Sender training produced no model file")
+
+            os.makedirs(os.path.dirname(resolved_output), exist_ok=True)
+            shutil.copy2(best_model, resolved_output)
+            log.info("Saved sender model to %s", resolved_output)
+
+            kraken_engine._sender_registry.invalidate(output_model_path)
+
+            return {"loss": None, "accuracy": accuracy, "cer": cer, "epochs": epochs}
+
+    result = await asyncio.to_thread(_run_sender_training)
+    return result
+
+
 @app.post("/segtrain")
 async def segtrain_model(
     file: UploadFile,

ocr-service/models.py

@@ -19,6 +19,7 @@ class OcrRequest(BaseModel):
     scriptType: str = "UNKNOWN"
     language: str = "de"
     regions: list[OcrRegion] | None = None
+    senderModelPath: str | None = None
 
 
 class OcrBlock(BaseModel):

ocr-service/test_sender_registry.py

@@ -0,0 +1,75 @@
+"""Tests for the per-sender model LRU registry in engines/kraken.py."""
+from unittest.mock import MagicMock, call, patch
+
+import pytest
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+def _make_registry(max_size=5):
+    from engines.kraken import _SenderModelRegistry
+    return _SenderModelRegistry(max_size=max_size)
+
+
+# ---------------------------------------------------------------------------
+# Tests
+# ---------------------------------------------------------------------------
+
+def test_cache_hit_returns_same_object():
+    """Second get_model call with the same path must return the cached object."""
+    registry = _make_registry()
+    mock_model = MagicMock(name="model_a")
+    with patch("engines.kraken._load_sender_model", return_value=mock_model) as loader:
+        m1 = registry.get_model("/app/models/sender_a.mlmodel")
+        m2 = registry.get_model("/app/models/sender_a.mlmodel")
+
+    assert m1 is m2
+    loader.assert_called_once()  # only loaded once despite two gets
+
+
+def test_lru_eviction_removes_least_recently_used():
+    """When the cache exceeds max_size, the oldest-accessed entry is evicted."""
+    registry = _make_registry(max_size=2)
+
+    def _side_effect(path):
+        return MagicMock(name=path)
+
+    with patch("engines.kraken._load_sender_model", side_effect=_side_effect):
+        registry.get_model("/app/models/sender_a.mlmodel")
+        registry.get_model("/app/models/sender_b.mlmodel")
+        registry.get_model("/app/models/sender_c.mlmodel")  # should evict 'a'
+
+    assert registry.size() == 2
+    # 'a' was the least-recently-used and should be gone
+    assert not registry._contains("/app/models/sender_a.mlmodel")
+
+
+def test_invalidate_removes_entry_from_cache():
+    """invalidate() must evict the entry so the next get reloads from disk."""
+    registry = _make_registry()
+    mock_model = MagicMock(name="model_x")
+    with patch("engines.kraken._load_sender_model", return_value=mock_model):
+        registry.get_model("/app/models/sender_x.mlmodel")
+        assert registry.size() == 1
+
+        registry.invalidate("/app/models/sender_x.mlmodel")
+        assert registry.size() == 0
+
+
+def test_path_outside_models_dir_raises():
+    """get_model must reject paths outside /app/models/ (path traversal guard)."""
+    registry = _make_registry()
+    with pytest.raises(ValueError, match="not allowed"):
+        registry.get_model("/etc/passwd")
+
+
+def test_load_failure_does_not_cache_broken_entry():
+    """A failed load must not leave a broken entry in the cache."""
+    registry = _make_registry()
+    with patch("engines.kraken._load_sender_model", side_effect=RuntimeError("corrupt model")):
+        with pytest.raises(RuntimeError, match="corrupt model"):
+            registry.get_model("/app/models/sender_bad.mlmodel")
+
+    assert registry.size() == 0

ocr-service/test_training_auth.py

@@ -67,3 +67,42 @@ async def test_train_returns_403_when_token_wrong():
             )
 
     assert response.status_code == 403
+
+
+# ─── /train-sender authentication ─────────────────────────────────────────────
+
+
+@pytest.mark.asyncio
+async def test_train_sender_returns_503_when_training_token_not_configured():
+    """POST /train-sender must return 503 when TRAINING_TOKEN env var is empty.
+
+    An empty token means the service was started without training configured.
+    Allowing requests through would grant unauthenticated access to the
+    training endpoint, contradicting the principle of failing closed.
+    """
+    with patch("main.TRAINING_TOKEN", ""), \
+         patch("main._models_ready", True):
+        async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as client:
+            response = await client.post(
+                "/train-sender",
+                data={"output_model_path": "/app/models/sender_test.mlmodel"},
+                files={"file": ("training.zip", _minimal_zip(), "application/zip")},
+            )
+
+    assert response.status_code == 503
+
+
+@pytest.mark.asyncio
+async def test_train_sender_returns_403_when_token_wrong():
+    """POST /train-sender must return 403 when TRAINING_TOKEN is set but header is wrong."""
+    with patch("main.TRAINING_TOKEN", "secret-token"), \
+         patch("main._models_ready", True):
+        async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as client:
+            response = await client.post(
+                "/train-sender",
+                data={"output_model_path": "/app/models/sender_test.mlmodel"},
+                files={"file": ("training.zip", _minimal_zip(), "application/zip")},
+                headers={"X-Training-Token": "wrong-token"},
+            )
+
+    assert response.status_code == 403