🐛(backend) duplicate a document as last-sibling

When a document is duplicated, it is duplicated at the direct right of
the duplicated document. Doing this force to move all the other
documents at the right, if it is duplicated at the root this can impact
a lot of documents, create lot of locks in the database. If the process
is stop for any reason then the paths can be in an inconsistent paths in
the Document table

CHANGELOG.md

@@ -21,6 +21,7 @@ and this project adheres to
 - ♿️(frontend) fix language dropdown ARIA for screen readers #2020
 - ♿️(frontend) fix waffle aria-label spacing for new-window links #2030
 - 🐛(backend) stop using add_sibling method to create sandbox document
+- 🐛(backend) duplicate a document as last-sibling
 
 ## [v4.8.1] - 2026-03-17
 

src/backend/core/api/viewsets.py

@@ -1361,7 +1361,7 @@ class DocumentViewSet(
             )
         else:
             duplicated_document = document_to_duplicate.add_sibling(
-                "right",
+                "last-sibling",
                 title=title,
                 content=base64_yjs_content,
                 attachments=attachments,

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

@@ -123,7 +123,7 @@ def test_api_documents_duplicate_success(index):
         image_refs[0][0]
     ]  # Only the first image key
     assert duplicated_document.get_parent() == document.get_parent()
-    assert duplicated_document.path == document.get_next_sibling().path
+    assert duplicated_document.path == document.get_last_sibling().path
 
     # Check that accesses were not duplicated.
     # The user who did the duplicate is forced as owner
@@ -180,6 +180,7 @@ def test_api_documents_duplicate_with_accesses_admin(role):
     client = APIClient()
     client.force_login(user)
 
+    documents_before = factories.DocumentFactory.create_batch(20)
     document = factories.DocumentFactory(
         users=[(user, role)],
         title="document with accesses",
@@ -187,6 +188,12 @@ def test_api_documents_duplicate_with_accesses_admin(role):
     user_access = factories.UserDocumentAccessFactory(document=document)
     team_access = factories.TeamDocumentAccessFactory(document=document)
 
+    documents_after = factories.DocumentFactory.create_batch(20)
+
+    all_documents = documents_before + [document] + documents_after
+
+    paths = {document.pk: document.path for document in all_documents}
+
     # Duplicate the document via the API endpoint requesting to duplicate accesses
     response = client.post(
         f"/api/v1.0/documents/{document.id!s}/duplicate/",
@@ -212,6 +219,10 @@ def test_api_documents_duplicate_with_accesses_admin(role):
     assert duplicated_accesses.get(user=user_access.user).role == user_access.role
     assert duplicated_accesses.get(team=team_access.team).role == team_access.role
 
+    for document in all_documents:
+        document.refresh_from_db()
+        assert document.path == paths[document.id]
+
 
 @pytest.mark.parametrize("role", ["editor", "reader"])
 def test_api_documents_duplicate_with_accesses_non_admin(role):