backend/src/main/java/org/raddatz/familienarchiv/document/DocumentService.java

@@ -68,6 +68,7 @@ import static org.raddatz.familienarchiv.document.DocumentSpecifications.*;
 public class DocumentService {
 
     private final DocumentRepository documentRepository;
+    private final DocumentTitleFactory documentTitleFactory;
     private final PersonService personService;
     private final FileService fileService;
     private final TagService tagService;
@@ -379,8 +380,14 @@ public class DocumentService {
 
         DocumentStatus statusBefore = doc.getStatus();
 
+        // Auto-title sync (#726): capture the machine title from the CURRENTLY-persisted state
+        // BEFORE any setter runs — the setters below overwrite date/location and applyDatePrecision
+        // skips nulls, so the old state must be read first. The submitted title is the catalog
+        // auto-title iff it equals this; only then does it follow date/location forward.
+        String autoTitleBefore = documentTitleFactory.build(doc);
+
         // 1. Einfache Felder Update
-        doc.setTitle(dto.getTitle());
+        doc.setTitle(resolveTitle(dto.getTitle(), autoTitleBefore, doc, dto));
         doc.setDocumentDate(dto.getDocumentDate());
         applyDatePrecision(doc, dto);
         validateDateRange(doc); // guard before any save (updateDocumentTags below persists)
@@ -452,6 +459,47 @@ public class DocumentService {
         return saved;
     }
 
+    /**
+     * Decides the title to persist on an edit (#726). The submitted title is the catalog
+     * auto-title only when it equals {@code autoBefore} (built from the stored state) — an exact
+     * comparison with no heuristic, relying on the edit form round-tripping the stored title
+     * verbatim when untouched. A machine title is rebuilt from the new state so a corrected
+     * date/location flows into it; a hand-written or freshly-typed title is kept verbatim. A blank
+     * submission is never persisted (title is always present) — it falls back to the rebuilt
+     * auto-title, which always carries at least the index.
+     */
+    private String resolveTitle(String submitted, String autoBefore, Document doc, DocumentUpdateDTO dto) {
+        if (submitted == null || submitted.isBlank()) {
+            return documentTitleFactory.build(projectedState(doc, dto));
+        }
+        if (!Objects.equals(submitted, autoBefore)) {
+            return submitted;
+        }
+        return documentTitleFactory.build(projectedState(doc, dto));
+    }
+
+    /**
+     * The document state the regenerated title is built from, mirroring {@code updateDocument}'s
+     * setter asymmetry exactly: {@code documentDate}/{@code location} are overwritten from the DTO
+     * (a null value clears the field), while precision/end/raw are taken from the DTO only when
+     * non-null and otherwise kept from the stored entity (see {@link #applyDatePrecision}). The
+     * index ({@code originalFilename}) is never touched by a metadata edit. A mismatch here would
+     * silently produce a wrong label, so it is kept lock-step with the real setters.
+     */
+    private Document projectedState(Document doc, DocumentUpdateDTO dto) {
+        return Document.builder()
+                .originalFilename(doc.getOriginalFilename())
+                .documentDate(dto.getDocumentDate())
+                .location(dto.getLocation())
+                .metaDatePrecision(dto.getMetaDatePrecision() != null
+                        ? dto.getMetaDatePrecision() : doc.getMetaDatePrecision())
+                .metaDateEnd(dto.getMetaDateEnd() != null
+                        ? dto.getMetaDateEnd() : doc.getMetaDateEnd())
+                .metaDateRaw(dto.getMetaDateRaw() != null
+                        ? dto.getMetaDateRaw() : doc.getMetaDateRaw())
+                .build();
+    }
+
     /**
      * Applies the three date-precision fields only when the DTO carries them.
      * A null field means "not submitted" — overwriting the stored value with null

backend/src/main/java/org/raddatz/familienarchiv/document/DocumentTitleFactory.java

@@ -23,7 +23,9 @@ public class DocumentTitleFactory {
      * location segment is dropped when blank.
      */
     public String build(Document doc) {
-        StringBuilder title = new StringBuilder(doc.getOriginalFilename());
+        // originalFilename is NOT NULL in production; guard only so a synthetic/partial entity
+        // never trips StringBuilder(null) with an opaque NPE.
+        StringBuilder title = new StringBuilder(doc.getOriginalFilename() == null ? "" : doc.getOriginalFilename());
         if (doc.getDocumentDate() != null && doc.getMetaDatePrecision() != DatePrecision.UNKNOWN) {
             title.append(SEPARATOR).append(DocumentTitleFormatter.formatTitleDate(
                     doc.getDocumentDate(), doc.getMetaDatePrecision(),

backend/src/test/java/org/raddatz/familienarchiv/document/DocumentServiceTest.java

@@ -5,6 +5,7 @@ import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.ArgumentCaptor;
 import org.mockito.InjectMocks;
 import org.mockito.Mock;
+import org.mockito.Spy;
 import org.mockito.junit.jupiter.MockitoExtension;
 import org.raddatz.familienarchiv.audit.AuditKind;
 import org.raddatz.familienarchiv.audit.AuditLogQueryService;
@@ -74,6 +75,9 @@ class DocumentServiceTest {
     @Mock AuditLogQueryService auditLogQueryService;
     @Mock TranscriptionBlockQueryService transcriptionBlockQueryService;
     @Mock ThumbnailAsyncRunner thumbnailAsyncRunner;
+    // Real factory (pure, dependency-free) so save-time title-regeneration tests exercise the
+    // shared composition rather than a stub — the #726 single source of truth.
+    @Spy DocumentTitleFactory documentTitleFactory = new DocumentTitleFactory();
     @InjectMocks DocumentService documentService;
 
     // ─── deleteDocument ───────────────────────────────────────────────────────
@@ -228,6 +232,179 @@ class DocumentServiceTest {
         assertThat(doc.getMetaDateRaw()).isEqualTo("Juni 1916");
     }
 
+    // ─── updateDocument save-time auto-title regeneration (#726) ──────────────
+    //
+    // Exact old-vs-new comparison: the title is the catalog auto-title iff the submitted
+    // title equals what the factory builds from the CURRENTLY-persisted state. The edit form
+    // round-trips the stored title verbatim when untouched, so an equal submission means the
+    // user did not type over it. makeStored() seeds index/date/precision/location and sets the
+    // stored title to the matching auto-title, mirroring a freshly-imported row.
+
+    private Document makeStored(String index, LocalDate date, DatePrecision precision, String location) {
+        Document doc = Document.builder()
+                .id(UUID.randomUUID())
+                .originalFilename(index)
+                .documentDate(date)
+                .metaDatePrecision(precision)
+                .location(location)
+                .receivers(new HashSet<>())
+                .tags(new HashSet<>())
+                .build();
+        doc.setTitle(documentTitleFactory.build(doc));
+        return doc;
+    }
+
+    /** A DTO that round-trips the stored auto-title untouched, with new date/precision/location. */
+    private static DocumentUpdateDTO editDto(String submittedTitle, LocalDate date,
+                                             DatePrecision precision, String location) {
+        DocumentUpdateDTO dto = new DocumentUpdateDTO();
+        dto.setTitle(submittedTitle);
+        dto.setDocumentDate(date);
+        dto.setMetaDatePrecision(precision);
+        dto.setLocation(location);
+        return dto;
+    }
+
+    private Document runUpdate(Document stored, DocumentUpdateDTO dto) throws Exception {
+        when(documentRepository.findById(stored.getId())).thenReturn(Optional.of(stored));
+        when(documentRepository.save(any())).thenReturn(stored);
+        documentService.updateDocument(stored.getId(), dto, null, null);
+        return stored;
+    }
+
+    @Test
+    void updateDocument_regeneratesAutoTitle_whenDateChanges() throws Exception {
+        Document stored = makeStored("C-0029", LocalDate.of(2028, 1, 1), DatePrecision.YEAR, "Berlin");
+        // title untouched ("C-0029 – 2028 – Berlin"), date corrected to 1928
+        DocumentUpdateDTO dto = editDto(stored.getTitle(), LocalDate.of(1928, 1, 1), DatePrecision.YEAR, "Berlin");
+
+        runUpdate(stored, dto);
+
+        assertThat(stored.getTitle()).isEqualTo("C-0029 – 1928 – Berlin");
+    }
+
+    @Test
+    void updateDocument_keepsHandWrittenTitle_whenDateChanges() throws Exception {
+        Document stored = makeStored("C-0029", LocalDate.of(1928, 1, 1), DatePrecision.YEAR, null);
+        stored.setTitle("C-0029 – Brief an Mutter"); // hand-written, ≠ auto-title
+        DocumentUpdateDTO dto = editDto("C-0029 – Brief an Mutter", LocalDate.of(1930, 1, 1), DatePrecision.YEAR, null);
+
+        runUpdate(stored, dto);
+
+        assertThat(stored.getTitle()).isEqualTo("C-0029 – Brief an Mutter");
+    }
+
+    @Test
+    void updateDocument_freshlyTypedTitleWins_overRegeneration() throws Exception {
+        Document stored = makeStored("C-0029", LocalDate.of(2028, 1, 1), DatePrecision.YEAR, "Berlin");
+        // user changed the date AND typed a new title in the same save
+        DocumentUpdateDTO dto = editDto("Geburtsanzeige", LocalDate.of(1928, 1, 1), DatePrecision.YEAR, "Berlin");
+
+        runUpdate(stored, dto);
+
+        assertThat(stored.getTitle()).isEqualTo("Geburtsanzeige");
+    }
+
+    @Test
+    void updateDocument_regeneratesWithNewDateAndLocation() throws Exception {
+        Document stored = makeStored("C-0029", LocalDate.of(2028, 1, 1), DatePrecision.YEAR, "Berlin");
+        DocumentUpdateDTO dto = editDto(stored.getTitle(), LocalDate.of(1928, 1, 1), DatePrecision.YEAR, "München");
+
+        runUpdate(stored, dto);
+
+        assertThat(stored.getTitle()).isEqualTo("C-0029 – 1928 – München");
+    }
+
+    @Test
+    void updateDocument_dropsTrailingLocationSegment_whenLocationCleared() throws Exception {
+        Document stored = makeStored("C-0029", LocalDate.of(1928, 1, 1), DatePrecision.YEAR, "Berlin");
+        // location cleared (null), title untouched
+        DocumentUpdateDTO dto = editDto(stored.getTitle(), LocalDate.of(1928, 1, 1), DatePrecision.YEAR, null);
+
+        runUpdate(stored, dto);
+
+        assertThat(stored.getTitle()).isEqualTo("C-0029 – 1928");
+    }
+
+    @Test
+    void updateDocument_regeneratedTitle_doesNotContainOldDate() throws Exception {
+        Document stored = makeStored("C-0029", LocalDate.of(2028, 1, 1), DatePrecision.YEAR, "Berlin");
+        DocumentUpdateDTO dto = editDto(stored.getTitle(), LocalDate.of(1928, 1, 1), DatePrecision.YEAR, "Berlin");
+
+        runUpdate(stored, dto);
+
+        assertThat(stored.getTitle()).doesNotContain("2028");
+    }
+
+    @Test
+    void updateDocument_relabelsOnPrecisionChange_yearToDay() throws Exception {
+        Document stored = makeStored("C-0029", LocalDate.of(1928, 1, 1), DatePrecision.YEAR, null);
+        // stored auto-title "C-0029 – 1928"; set a full day at DAY precision
+        DocumentUpdateDTO dto = editDto(stored.getTitle(), LocalDate.of(1928, 1, 15), DatePrecision.DAY, null);
+
+        runUpdate(stored, dto);
+
+        assertThat(stored.getTitle()).isEqualTo("C-0029 – 15. Januar 1928");
+    }
+
+    @Test
+    void updateDocument_populatesTitle_whenDateAddedToUnknownRow() throws Exception {
+        Document stored = makeStored("C-0029", null, DatePrecision.UNKNOWN, null);
+        // stored auto-title is just "C-0029"; add a 1928 YEAR date
+        DocumentUpdateDTO dto = editDto(stored.getTitle(), LocalDate.of(1928, 1, 1), DatePrecision.YEAR, null);
+
+        runUpdate(stored, dto);
+
+        assertThat(stored.getTitle()).isEqualTo("C-0029 – 1928");
+    }
+
+    @Test
+    void updateDocument_roundTripsSeasonLabel() throws Exception {
+        Document stored = makeStored("C-0029", LocalDate.of(1943, 4, 1), DatePrecision.SEASON, null);
+        stored.setMetaDateRaw("Frühling 1943");
+        stored.setTitle(documentTitleFactory.build(stored)); // "C-0029 – Frühling 1943"
+        DocumentUpdateDTO dto = editDto(stored.getTitle(), LocalDate.of(1943, 4, 1), DatePrecision.SEASON, null);
+        dto.setMetaDateRaw("Frühling 1943");
+
+        runUpdate(stored, dto);
+
+        assertThat(stored.getTitle()).isEqualTo("C-0029 – Frühling 1943");
+    }
+
+    @Test
+    void updateDocument_doesNotRegenerateToBlank_whenSubmittedTitleEmpty() throws Exception {
+        Document stored = makeStored("C-0029", LocalDate.of(1928, 1, 1), DatePrecision.YEAR, "Berlin");
+        DocumentUpdateDTO dto = editDto("", LocalDate.of(1928, 1, 1), DatePrecision.YEAR, "Berlin");
+
+        runUpdate(stored, dto);
+
+        assertThat(stored.getTitle()).isNotBlank();
+    }
+
+    @Test
+    void updateDocument_treatsFileReplacedDoc_asManual() throws Exception {
+        // originalFilename was reassigned by an earlier file-replace, so the stored title (built
+        // at import from the old index) no longer matches build(currentState) → treated as manual.
+        Document stored = makeStored("scan_2024.pdf", LocalDate.of(1928, 1, 1), DatePrecision.YEAR, "Berlin");
+        stored.setTitle("C-0029 – 1928 – Berlin"); // legacy import title, ≠ build("scan_2024.pdf"…)
+        DocumentUpdateDTO dto = editDto("C-0029 – 1928 – Berlin", LocalDate.of(1930, 1, 1), DatePrecision.YEAR, "Berlin");
+
+        runUpdate(stored, dto);
+
+        assertThat(stored.getTitle()).isEqualTo("C-0029 – 1928 – Berlin");
+    }
+
+    @Test
+    void updateDocument_idempotent_whenNothingChanges() throws Exception {
+        Document stored = makeStored("C-0029", LocalDate.of(1928, 1, 1), DatePrecision.YEAR, "Berlin");
+        String before = stored.getTitle();
+        DocumentUpdateDTO dto = editDto(before, LocalDate.of(1928, 1, 1), DatePrecision.YEAR, "Berlin");
+
+        runUpdate(stored, dto);
+
+        assertThat(stored.getTitle()).isEqualTo(before);
+    }
+
     // ─── updateDocument date-range validation (#678) ──────────────────────────
 
     /** Builds a stored doc ready for an updateDocument call (collections initialised). */