refactor(document): extract title composition into shared DocumentTitleFactory (#726)

Move DocumentTitleFormatter from importing into the document package and
introduce DocumentTitleFactory there as the single source of truth for the
{index} – {dateLabel} – {location} formula. DocumentImporter now consumes the
factory instead of owning the composition; the document package owns the rule,
importing depends on it (not the reverse). No behavioral change — importer
title assertions and the #666 fixture parity test stay green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

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

@@ -0,0 +1,82 @@
+package org.raddatz.familienarchiv.document;
+
+import org.junit.jupiter.api.Test;
+
+import java.time.LocalDate;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * The auto-title composition {@code {index} – {dateLabel} – {location}} in isolation.
+ * The honest date-label forms themselves are pinned by {@link DocumentTitleFormatterTest}
+ * against the shared #666 fixture; here we assert only how the factory composes the
+ * three segments and which segments it omits.
+ */
+class DocumentTitleFactoryTest {
+
+    private final DocumentTitleFactory factory = new DocumentTitleFactory();
+
+    private static Document.DocumentBuilder doc(String index) {
+        return Document.builder()
+                .originalFilename(index)
+                .metaDatePrecision(DatePrecision.UNKNOWN);
+    }
+
+    @Test
+    void index_only_when_no_date_and_no_location() {
+        assertThat(factory.build(doc("C-0029").build())).isEqualTo("C-0029");
+    }
+
+    @Test
+    void index_and_year_date() {
+        Document d = doc("C-0029")
+                .documentDate(LocalDate.of(1928, 1, 15))
+                .metaDatePrecision(DatePrecision.YEAR)
+                .build();
+        assertThat(factory.build(d)).isEqualTo("C-0029 – 1928");
+    }
+
+    @Test
+    void index_date_and_location() {
+        Document d = doc("C-0029")
+                .documentDate(LocalDate.of(1928, 1, 15))
+                .metaDatePrecision(DatePrecision.YEAR)
+                .location("Berlin")
+                .build();
+        assertThat(factory.build(d)).isEqualTo("C-0029 – 1928 – Berlin");
+    }
+
+    @Test
+    void location_without_date_attaches_directly_to_index() {
+        Document d = doc("C-0029").location("Berlin").build();
+        assertThat(factory.build(d)).isEqualTo("C-0029 – Berlin");
+    }
+
+    @Test
+    void unknown_precision_omits_the_date_segment() {
+        Document d = doc("C-0029")
+                .documentDate(LocalDate.of(1928, 1, 15))
+                .metaDatePrecision(DatePrecision.UNKNOWN)
+                .build();
+        assertThat(factory.build(d)).isEqualTo("C-0029");
+    }
+
+    @Test
+    void blank_location_is_omitted() {
+        Document d = doc("C-0029")
+                .documentDate(LocalDate.of(1928, 1, 15))
+                .metaDatePrecision(DatePrecision.YEAR)
+                .location("   ")
+                .build();
+        assertThat(factory.build(d)).isEqualTo("C-0029 – 1928");
+    }
+
+    @Test
+    void day_precision_renders_the_full_german_label() {
+        Document d = doc("C-0029")
+                .documentDate(LocalDate.of(1928, 1, 15))
+                .metaDatePrecision(DatePrecision.DAY)
+                .build();
+        assertThat(factory.build(d)).isEqualTo("C-0029 – 15. Januar 1928");
+    }
+}

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

@@ -1,10 +1,9 @@
-package org.raddatz.familienarchiv.importing;
+package org.raddatz.familienarchiv.document;
 
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import org.junit.jupiter.api.DynamicTest;
 import org.junit.jupiter.api.TestFactory;
-import org.raddatz.familienarchiv.document.DatePrecision;
 
 import java.nio.file.Files;
 import java.nio.file.Path;

backend/src/test/java/org/raddatz/familienarchiv/importing/DocumentImporterTest.java

@@ -11,6 +11,7 @@ import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 import org.raddatz.familienarchiv.document.Document;
 import org.raddatz.familienarchiv.document.DocumentService;
+import org.raddatz.familienarchiv.document.DocumentTitleFactory;
 import org.raddatz.familienarchiv.document.DocumentStatus;
 import org.raddatz.familienarchiv.document.ThumbnailAsyncRunner;
 import org.raddatz.familienarchiv.person.Person;
@@ -59,8 +60,10 @@ class DocumentImporterTest {
         // override this stub locally (load_skipsFile_whenMagicByteCheckThrowsIoException).
         lenient().when(fileStreamOpener.open(any(File.class)))
                 .thenAnswer(inv -> new java.io.FileInputStream(inv.getArgument(0, File.class)));
-        importer = new DocumentImporter(documentService, personService, tagService, s3Client,
-                thumbnailAsyncRunner, fileStreamOpener);
+        // Real factory (pure, dependency-free) so the title-content assertions below exercise
+        // the shared composition rather than a stub — the #726 single source of truth.
+        importer = new DocumentImporter(documentService, new DocumentTitleFactory(), personService,
+                tagService, s3Client, thumbnailAsyncRunner, fileStreamOpener);
         ReflectionTestUtils.setField(importer, "bucketName", "test-bucket");
     }