feat(document): thread an undated filter through search and the /ids path

Adds an optional `undated` query param to GET /api/documents/search and
/api/documents/ids, threaded through searchDocuments and findIdsForFilter
into the shared buildSearchSpec via undatedOnly(boolean). undated=true also
bypasses the pure-text RELEVANCE SQL shortcut, which skips buildSearchSpec
and would otherwise drop the predicate. The read GET stays unguarded
(WebMvc authz test pins 200 for an authenticated user, 401 unauthenticated).
A locking test proves the in-memory SENDER sort keeps undated letters under
their sender.

Refs #668

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

@@ -313,9 +313,10 @@ public class DocumentController {
             @RequestParam(required = false) String tagQ,
             @RequestParam(required = false) DocumentStatus status,
             @RequestParam(required = false) String tagOp,
+            @RequestParam(required = false) Boolean undated,
             Authentication authentication) {
         TagOperator operator = "OR".equalsIgnoreCase(tagOp) ? TagOperator.OR : TagOperator.AND;
-        List<UUID> ids = documentService.findIdsForFilter(q, from, to, senderId, receiverId, tags, tagQ, status, operator);
+        List<UUID> ids = documentService.findIdsForFilter(q, from, to, senderId, receiverId, tags, tagQ, status, operator, Boolean.TRUE.equals(undated));
         if (ids.size() > BULK_EDIT_FILTER_MAX_IDS) {
             throw DomainException.badRequest(ErrorCode.BULK_EDIT_TOO_MANY_IDS,
                     "Filter matches " + ids.size() + " documents — refine filter (max " + BULK_EDIT_FILTER_MAX_IDS + ")");
@@ -375,6 +376,7 @@ public class DocumentController {
             @Parameter(description = "Sort field") @RequestParam(required = false) DocumentSort sort,
             @Parameter(description = "Sort direction: ASC or DESC") @RequestParam(required = false, defaultValue = "DESC") String dir,
             @Parameter(description = "Tag operator: AND (default) or OR") @RequestParam(required = false) String tagOp,
+            @Parameter(description = "Restrict to undated documents (meta_date IS NULL)") @RequestParam(required = false) Boolean undated,
             // @Max on page guards against overflow when pageable.getOffset() is computed
             // as page * size — Integer.MAX_VALUE * 50 would wrap to a negative long, which
             // Hibernate cheerfully turns into an invalid SQL OFFSET.
@@ -387,7 +389,7 @@ public class DocumentController {
         // defaults to AND, which matches the frontend default and keeps old clients working.
         TagOperator operator = "OR".equalsIgnoreCase(tagOp) ? TagOperator.OR : TagOperator.AND;
         Pageable pageable = PageRequest.of(page, size);
-        return ResponseEntity.ok(documentService.searchDocuments(q, from, to, senderId, receiverId, tags, tagQ, status, sort, dir, operator, pageable));
+        return ResponseEntity.ok(documentService.searchDocuments(q, from, to, senderId, receiverId, tags, tagQ, status, sort, dir, operator, Boolean.TRUE.equals(undated), pageable));
     }
 
     @GetMapping(value = "/density", produces = MediaType.APPLICATION_JSON_VALUE)

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

@@ -171,7 +171,7 @@ public class DocumentService {
                 hasFts, ftsIds, null, null,
                 filters.sender(), filters.receiver(),
                 filters.tags(), filters.tagQ(),
-                filters.status(), filters.tagOperator());
+                filters.status(), filters.tagOperator(), false);
         return documentRepository.findAll(spec).stream()
                 .map(Document::getDocumentDate)
                 .filter(Objects::nonNull)
@@ -501,7 +501,8 @@ public class DocumentService {
      */
     @Transactional(readOnly = true)
     public List<UUID> findIdsForFilter(String text, LocalDate from, LocalDate to, UUID sender, UUID receiver,
-                                       List<String> tags, String tagQ, DocumentStatus status, TagOperator tagOperator) {
+                                       List<String> tags, String tagQ, DocumentStatus status, TagOperator tagOperator,
+                                       boolean undated) {
         boolean hasText = StringUtils.hasText(text);
         List<UUID> rankedIds = null;
         if (hasText) {
@@ -510,7 +511,7 @@ public class DocumentService {
         }
 
         Specification<Document> spec = buildSearchSpec(
-                hasText, rankedIds, from, to, sender, receiver, tags, tagQ, status, tagOperator);
+                hasText, rankedIds, from, to, sender, receiver, tags, tagQ, status, tagOperator, undated);
         return documentRepository.findAll(spec).stream().map(Document::getId).toList();
     }
 
@@ -524,7 +525,8 @@ public class DocumentService {
                                                     LocalDate from, LocalDate to,
                                                     UUID sender, UUID receiver,
                                                     List<String> tags, String tagQ,
-                                                    DocumentStatus status, TagOperator tagOperator) {
+                                                    DocumentStatus status, TagOperator tagOperator,
+                                                    boolean undated) {
         boolean useOrLogic = tagOperator == TagOperator.OR;
         List<Set<UUID>> expandedTagSets = tagService.expandTagNamesToDescendantIdSets(tags);
         Specification<Document> textSpec = hasText ? hasIds(ftsIds) : (root, query, cb) -> null;
@@ -534,7 +536,8 @@ public class DocumentService {
                 .and(hasReceiver(receiver))
                 .and(hasTags(expandedTagSets, useOrLogic))
                 .and(hasTagPartial(tagQ))
-                .and(hasStatus(status));
+                .and(hasStatus(status))
+                .and(undatedOnly(undated));
     }
 
     /**
@@ -663,11 +666,13 @@ public class DocumentService {
     }
 
     // 1. Allgemeine Suche (für das Suchfeld im Frontend)
-    public DocumentSearchResult searchDocuments(String text, LocalDate from, LocalDate to, UUID sender, UUID receiver, List<String> tags, String tagQ, DocumentStatus status, DocumentSort sort, String dir, TagOperator tagOperator, Pageable pageable) {
+    public DocumentSearchResult searchDocuments(String text, LocalDate from, LocalDate to, UUID sender, UUID receiver, List<String> tags, String tagQ, DocumentStatus status, DocumentSort sort, String dir, TagOperator tagOperator, boolean undated, Pageable pageable) {
         boolean hasText = StringUtils.hasText(text);
 
         // Pure-text RELEVANCE: push pagination into SQL — skip findAllMatchingIdsByFts entirely (ADR-008).
-        if (isPureTextRelevance(hasText, sort, from, to, sender, receiver, tags, tagQ, status)) {
+        // An active undated filter must NOT take this path: it bypasses buildSearchSpec, so the
+        // undatedOnly predicate would be silently dropped.
+        if (!undated && isPureTextRelevance(hasText, sort, from, to, sender, receiver, tags, tagQ, status)) {
             return relevanceSortedPageFromSql(text, pageable);
         }
 
@@ -678,7 +683,7 @@ public class DocumentService {
         }
 
         Specification<Document> spec = buildSearchSpec(
-                hasText, rankedIds, from, to, sender, receiver, tags, tagQ, status, tagOperator);
+                hasText, rankedIds, from, to, sender, receiver, tags, tagQ, status, tagOperator, undated);
 
         // SENDER and RECEIVER sorts load the full match set and slice in-memory.
         // JPA's Sort.by("sender.lastName") generates an INNER JOIN that silently drops