perf: migrate 3 serialisers.py Document permission sites to permitted_document_ids

Migrates _get_viewable_duplicates(), PaperlessTaskSerializer.get_duplicate_documents(),
and the ShareLinkBundle document field queryset to use permitted_document_ids()
instead of get_objects_for_user_owner_aware()/get_objects_for_user(), consolidating
onto the shared permission-filtering helper. The is_staff gate in
get_duplicate_documents() is preserved as-is.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GRp4kf1mdn9ruv81zWAmh2

src/documents/serialisers.py

@@ -39,7 +39,6 @@ from drf_spectacular.utils import extend_schema_field
 from drf_spectacular.utils import extend_schema_serializer
 from drf_writable_nested.serializers import NestedUpdateMixin
 from guardian.core import ObjectPermissionChecker
-from guardian.shortcuts import get_objects_for_user
 from guardian.shortcuts import get_users_with_perms
 from guardian.utils import get_group_obj_perms_model
 from guardian.utils import get_user_obj_perms_model
@@ -80,8 +79,8 @@ from documents.models import WorkflowTrigger
 from documents.parsers import is_mime_type_supported
 from documents.permissions import get_document_count_filter_for_user
 from documents.permissions import get_groups_with_only_permission
-from documents.permissions import get_objects_for_user_owner_aware
 from documents.permissions import has_perms_owner_aware
+from documents.permissions import permitted_document_ids
 from documents.permissions import set_permissions_for_object
 from documents.regex import validate_regex_pattern
 from documents.templating.filepath import validate_filepath_template_and_render
@@ -1011,13 +1010,8 @@ def _get_viewable_duplicates(
     ).exclude(pk=document.pk)
     duplicates = duplicates.filter(root_document__isnull=True)
     duplicates = duplicates.order_by("-created")
-    allowed = get_objects_for_user_owner_aware(
-        user,
-        "documents.view_document",
-        Document,
-        include_deleted=True,
-    )
-    return duplicates.filter(id__in=allowed)
+    allowed_ids = permitted_document_ids(user, include_deleted=True)
+    return duplicates.filter(id__in=allowed_ids)
 
 
 class DuplicateDocumentSummarySerializer(serializers.Serializer[dict[str, Any]]):
@@ -2659,13 +2653,8 @@ class TaskSerializerV9(serializers.ModelSerializer[PaperlessTask]):
         user = request.user
         qs = Document.global_objects.filter(pk=dup_of)
         if not user.is_staff:
-            with_perms = get_objects_for_user(
-                user,
-                "documents.view_document",
-                qs,
-                accept_global_perms=False,
-            )
-            qs = with_perms | qs.filter(owner=user) | qs.filter(owner__isnull=True)
+            allowed_ids = permitted_document_ids(user, include_deleted=True)
+            qs = qs.filter(pk__in=allowed_ids)
         return list(qs.values("id", "title", "deleted_at"))
 
 
@@ -3515,8 +3504,6 @@ class StoragePathTestSerializer(SerializerWithPerms):
             document_field = self.fields.get("document")
             if not isinstance(document_field, serializers.PrimaryKeyRelatedField):
                 return
-            document_field.queryset = get_objects_for_user_owner_aware(
-                user,
-                "documents.view_document",
-                Document,
+            document_field.queryset = Document.objects.filter(
+                id__in=permitted_document_ids(user),
             )

src/documents/tests/test_permission_filtering_security.py

@@ -12,6 +12,7 @@ from guardian.shortcuts import assign_perm
 from rest_framework.test import APIClient
 
 from documents.permissions import permitted_document_ids
+from documents.serialisers import _get_viewable_duplicates
 from documents.tests.factories import DocumentFactory
 
 
@@ -193,3 +194,21 @@ class TestAiChatAllDocumentsPermissionBoundary:
         visible_ids = {doc.pk for doc in kwargs["documents"]}
         assert shared.pk in visible_ids
         assert not_shared.pk not in visible_ids
+
+
+@pytest.mark.django_db
+class TestDuplicateDocumentsPermissionBoundary:
+    def test_get_viewable_duplicates_includes_soft_deleted_but_respects_perms(self):
+        owner = User.objects.create_user(username="owner")
+        stranger = User.objects.create_user(username="mallory")
+        original = DocumentFactory(owner=owner, checksum="dupe-checksum")
+        dup_visible = DocumentFactory(owner=owner, checksum="dupe-checksum")
+        dup_hidden = DocumentFactory(owner=owner, checksum="dupe-checksum")
+        dup_hidden.delete()  # soft delete, should still be found (include_deleted=True)
+        assign_perm("view_document", stranger, dup_visible)
+
+        result_owner = _get_viewable_duplicates(original, owner)
+        assert {d.pk for d in result_owner} == {dup_visible.pk, dup_hidden.pk}
+
+        result_stranger = _get_viewable_duplicates(original, stranger)
+        assert {d.pk for d in result_stranger} == {dup_visible.pk}