🐛(backend) do not filter deleted docs for the owner in the tree view

Fixes the bug described in #1254 (Delete document request conflict)

In the tree request, deleted documents for
which the user is the owner are not filtered anymore.

CHANGELOG.md

@@ -10,6 +10,10 @@ and this project adheres to
 
 - 💄(frontend) improve comments highlights #1961
 
+### Fixed
+
+- 🐛(backend) do not filter deleted documents for the owner in the tree #2121
+
 ## [v4.8.3] - 2026-03-23
 
 ### Changed

src/backend/core/api/viewsets.py

@@ -1209,7 +1209,20 @@ class DocumentViewSet(
                 path__startswith=ancestor.path, depth=ancestor.depth + 1
             )
 
-        children = self.queryset.filter(children_clause, deleted_at__isnull=True)
+        # Include deleted documents owned by the user, if any.
+        if request.user.is_authenticated:
+            owned_document_ids = models.DocumentAccess.objects.filter(
+                user=user,
+                role=models.RoleChoices.OWNER,
+                document__deleted_at__isnull=False,
+            ).values("document_id")
+
+            children = self.queryset.filter(
+                children_clause,
+                db.Q(deleted_at__isnull=True) | db.Q(id__in=owned_document_ids),
+            )
+        else:
+            children = self.queryset.filter(children_clause, deleted_at__isnull=True)
 
         queryset = (
             ancestors.select_related("creator").filter(

src/backend/core/tests/documents/test_api_documents_tree.py

@@ -1258,3 +1258,58 @@ def test_api_documents_tree_list_deleted_document_owner(django_assert_num_querie
     assert content["children"][0][
         "deleted_at"
     ] == child.ancestors_deleted_at.isoformat().replace("+00:00", "Z")
+
+
+def test_api_documents_tree_deleted_child_visible_to_owner():
+    """
+    A deleted child document should appear in the tree for users who are its direct owner,
+    even when they are not the owner of the parent.
+    """
+    user = factories.UserFactory()
+    client = APIClient()
+    client.force_login(user)
+
+    parent = factories.DocumentFactory(link_reach="public")
+    owned_child = factories.DocumentFactory(parent=parent, users=[(user, "owner")])
+    other_child = factories.DocumentFactory(parent=parent)
+
+    owned_child.soft_delete()
+    owned_child.refresh_from_db()
+
+    response = client.get(f"/api/v1.0/documents/{parent.id!s}/tree/")
+    assert response.status_code == 200
+
+    content = response.json()
+    child_ids = [c["id"] for c in content["children"]]
+    assert str(owned_child.id) in child_ids
+    assert str(other_child.id) in child_ids
+
+    owned_child_data = next(
+        c for c in content["children"] if c["id"] == str(owned_child.id)
+    )
+    assert owned_child_data["deleted_at"] == owned_child.deleted_at.isoformat().replace(
+        "+00:00", "Z"
+    )
+
+
+def test_api_documents_tree_deleted_child_hidden_from_non_owner():
+    """
+    A deleted child document should not appear in the tree for users who are not its owner.
+    """
+    user = factories.UserFactory()
+    client = APIClient()
+    client.force_login(user)
+
+    parent = factories.DocumentFactory(link_reach="public")
+    deleted_child = factories.DocumentFactory(parent=parent)
+    visible_child = factories.DocumentFactory(parent=parent)
+
+    deleted_child.soft_delete()
+
+    response = client.get(f"/api/v1.0/documents/{parent.id!s}/tree/")
+    assert response.status_code == 200
+
+    content = response.json()
+    child_ids = [c["id"] for c in content["children"]]
+    assert str(deleted_child.id) not in child_ids
+    assert str(visible_child.id) in child_ids