feat(bulk-edit): add GET /api/documents/ids endpoint

READ_ALL-gated endpoint returning all document UUIDs matching the same
filter parameters as /search, ignoring page/size. Powers the "Alle X
editieren" fast path so the bulk-edit page can replace the selection
with every match in one round-trip.

Refs #225

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

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

@@ -281,6 +281,22 @@ public class DocumentController {
         return new BulkEditResult(updated, errors);
     }
 
+    @GetMapping("/ids")
+    @RequirePermission(Permission.READ_ALL)
+    public List<UUID> getDocumentIds(
+            @RequestParam(required = false) String q,
+            @RequestParam(required = false) LocalDate from,
+            @RequestParam(required = false) LocalDate to,
+            @RequestParam(required = false) UUID senderId,
+            @RequestParam(required = false) UUID receiverId,
+            @RequestParam(required = false, name = "tag") List<String> tags,
+            @RequestParam(required = false) String tagQ,
+            @RequestParam(required = false) DocumentStatus status,
+            @RequestParam(required = false) String tagOp) {
+        TagOperator operator = "OR".equalsIgnoreCase(tagOp) ? TagOperator.OR : TagOperator.AND;
+        return documentService.findIdsForFilter(q, from, to, senderId, receiverId, tags, tagQ, status, operator);
+    }
+
     @PostMapping(value = "/batch-metadata", consumes = MediaType.APPLICATION_JSON_VALUE)
     @RequirePermission(Permission.READ_ALL)
     public List<DocumentBatchSummary> batchMetadata(@RequestBody BatchMetadataRequest request) {

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

@@ -350,6 +350,35 @@ public class DocumentService {
         return documentRepository.save(doc);
     }
 
+    /**
+     * Returns all document IDs matching the given filter parameters, ignoring
+     * pagination. Used by the bulk-edit "Alle X editieren" fast path so the
+     * frontend can replace the selection with every match across pages in one
+     * round-trip.
+     */
+    public List<UUID> findIdsForFilter(String text, LocalDate from, LocalDate to, UUID sender, UUID receiver,
+                                       List<String> tags, String tagQ, DocumentStatus status, TagOperator tagOperator) {
+        boolean hasText = StringUtils.hasText(text);
+        List<UUID> rankedIds = null;
+        if (hasText) {
+            rankedIds = documentRepository.findRankedIdsByFts(text);
+            if (rankedIds.isEmpty()) return List.of();
+        }
+        boolean useOrLogic = tagOperator == TagOperator.OR;
+        List<Set<UUID>> expandedTagSets = tagService.expandTagNamesToDescendantIdSets(tags);
+
+        Specification<Document> textSpec = hasText ? hasIds(rankedIds) : (root, query, cb) -> null;
+        Specification<Document> spec = Specification.where(textSpec)
+                .and(isBetween(from, to))
+                .and(hasSender(sender))
+                .and(hasReceiver(receiver))
+                .and(hasTags(expandedTagSets, useOrLogic))
+                .and(hasTagPartial(tagQ))
+                .and(hasStatus(status));
+
+        return documentRepository.findAll(spec).stream().map(Document::getId).toList();
+    }
+
     /**
      * Returns lightweight summaries (id, title, server PDF URL) for the given
      * document IDs. Unknown IDs are silently dropped — the consumer is the

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

@@ -1016,6 +1016,39 @@ class DocumentControllerTest {
         verify(documentService).applyBulkEditToDocument(eq(id2), any());
     }
 
+    // ─── GET /api/documents/ids ──────────────────────────────────────────────
+
+    @Test
+    void getDocumentIds_returns401_whenUnauthenticated() throws Exception {
+        mockMvc.perform(get("/api/documents/ids"))
+                .andExpect(status().isUnauthorized());
+    }
+
+    @Test
+    @WithMockUser(authorities = "READ_ALL")
+    void getDocumentIds_returns200_andDelegatesToService() throws Exception {
+        UUID id = UUID.randomUUID();
+        when(documentService.findIdsForFilter(any(), any(), any(), any(), any(), any(), any(), any(), any()))
+                .thenReturn(List.of(id));
+
+        mockMvc.perform(get("/api/documents/ids"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$[0]").value(id.toString()));
+    }
+
+    @Test
+    @WithMockUser(authorities = "READ_ALL")
+    void getDocumentIds_passesSenderIdParamToService() throws Exception {
+        UUID senderId = UUID.randomUUID();
+        when(documentService.findIdsForFilter(any(), any(), any(), eq(senderId), any(), any(), any(), any(), any()))
+                .thenReturn(List.of());
+
+        mockMvc.perform(get("/api/documents/ids").param("senderId", senderId.toString()))
+                .andExpect(status().isOk());
+
+        verify(documentService).findIdsForFilter(any(), any(), any(), eq(senderId), any(), any(), any(), any(), any());
+    }
+
     // ─── POST /api/documents/batch-metadata ──────────────────────────────────
 
     @Test

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

@@ -2089,6 +2089,32 @@ class DocumentServiceTest {
         assertThat(doc.getDocumentLocation()).isEqualTo("NewLocation");
     }
 
+    // ─── findIdsForFilter ────────────────────────────────────────────────────
+
+    @Test
+    void findIdsForFilter_returnsAllMatchingIds_uncapped() {
+        Document d1 = Document.builder().id(UUID.randomUUID()).title("A").build();
+        Document d2 = Document.builder().id(UUID.randomUUID()).title("B").build();
+        when(documentRepository.findAll(any(org.springframework.data.jpa.domain.Specification.class)))
+                .thenReturn(List.of(d1, d2));
+
+        List<UUID> result = documentService.findIdsForFilter(
+                null, null, null, null, null, null, null, null, null);
+
+        assertThat(result).containsExactly(d1.getId(), d2.getId());
+    }
+
+    @Test
+    void findIdsForFilter_returnsEmpty_whenFtsHasNoMatches() {
+        when(documentRepository.findRankedIdsByFts("xyz")).thenReturn(List.of());
+
+        List<UUID> result = documentService.findIdsForFilter(
+                "xyz", null, null, null, null, null, null, null, null);
+
+        assertThat(result).isEmpty();
+        verify(documentRepository, never()).findAll(any(org.springframework.data.jpa.domain.Specification.class));
+    }
+
     // ─── batchMetadata ───────────────────────────────────────────────────────
 
     @Test