test(geschichte): add integration tests for documentId JPQL EXISTS filter

Verifies the EXISTS subquery in findSummaries actually filters by document
membership — a journey containing the document appears, one without does not.

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

backend/src/test/java/org/raddatz/familienarchiv/geschichte/GeschichteListProjectionTest.java

@@ -4,6 +4,11 @@ import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.raddatz.familienarchiv.PostgresContainerConfig;
 import org.raddatz.familienarchiv.config.FlywayConfig;
+import org.raddatz.familienarchiv.document.Document;
+import org.raddatz.familienarchiv.document.DocumentRepository;
+import org.raddatz.familienarchiv.document.DocumentStatus;
+import org.raddatz.familienarchiv.geschichte.journeyitem.JourneyItem;
+import org.raddatz.familienarchiv.geschichte.journeyitem.JourneyItemRepository;
 import org.raddatz.familienarchiv.person.Person;
 import org.raddatz.familienarchiv.person.PersonRepository;
 import org.raddatz.familienarchiv.user.AppUser;
@@ -27,6 +32,8 @@ class GeschichteListProjectionTest {
     @Autowired GeschichteRepository geschichteRepository;
     @Autowired AppUserRepository appUserRepository;
     @Autowired PersonRepository personRepository;
+    @Autowired DocumentRepository documentRepository;
+    @Autowired JourneyItemRepository journeyItemRepository;
 
     AppUser author;
     AppUser otherAuthor;
@@ -170,6 +177,35 @@ class GeschichteListProjectionTest {
         assertThat(result.get(0).getTitle()).isEqualTo("Both");
     }
 
+    // ─── documentId filter (JPQL EXISTS subquery) ────────────────────────────
+
+    @Test
+    void findSummaries_with_documentId_returns_journey_containing_that_document() {
+        Document doc = documentRepository.save(Document.builder()
+                .title("Brief").originalFilename("brief.pdf").status(DocumentStatus.UPLOADED).build());
+        Geschichte withDoc = geschichteRepository.save(journey("Reise mit Dokument", author));
+        Geschichte withoutDoc = geschichteRepository.save(journey("Reise ohne Dokument", author));
+        journeyItemRepository.save(JourneyItem.builder()
+                .geschichte(withDoc).document(doc).position(1).build());
+
+        List<GeschichteSummary> result = geschichteRepository.findSummaries(
+                GeschichteStatus.PUBLISHED, null, sentinel(), 0, doc.getId());
+
+        assertThat(result).hasSize(1);
+        assertThat(result.get(0).getTitle()).isEqualTo("Reise mit Dokument");
+        assertThat(result).extracting(GeschichteSummary::getTitle).doesNotContain("Reise ohne Dokument");
+    }
+
+    @Test
+    void findSummaries_with_unknown_documentId_returns_empty() {
+        geschichteRepository.save(journey("Irgendeine Reise", author));
+
+        List<GeschichteSummary> result = geschichteRepository.findSummaries(
+                GeschichteStatus.PUBLISHED, null, sentinel(), 0, UUID.randomUUID());
+
+        assertThat(result).isEmpty();
+    }
+
     // ─── helpers ─────────────────────────────────────────────────────────────
 
     private Geschichte published(String title, AppUser writer) {
@@ -189,6 +225,16 @@ class GeschichteListProjectionTest {
                 .build();
     }
 
+    private Geschichte journey(String title, AppUser writer) {
+        return Geschichte.builder()
+                .title(title)
+                .status(GeschichteStatus.PUBLISHED)
+                .type(GeschichteType.JOURNEY)
+                .author(writer)
+                .publishedAt(LocalDateTime.now())
+                .build();
+    }
+
     /** Sentinel UUID passed when personCount=0 — the IN() clause is never evaluated. */
     private List<UUID> sentinel() {
         return List.of(UUID.fromString("00000000-0000-0000-0000-000000000000"));