Fully qualify id columns for keyset pagination

When joining in multiple relations, the `id > ?` and `id < ?` need to be
fully qualified with a table name.

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/212660

app/finders/projects_finder.rb

@@ -142,8 +142,8 @@ class ProjectsFinder < UnionFinder
   # rubocop: disable CodeReuse/ActiveRecord
   def by_ids(items)
     items = items.where(id: project_ids_relation) if project_ids_relation
-    items = items.where('id > ?', params[:id_after]) if params[:id_after]
-    items = items.where('id < ?', params[:id_before]) if params[:id_before]
+    items = items.where('projects.id > ?', params[:id_after]) if params[:id_after]
+    items = items.where('projects.id < ?', params[:id_before]) if params[:id_before]
     items
   end
   # rubocop: enable CodeReuse/ActiveRecord

changelogs/unreleased/ab-keyset-ambig-bug.yml

+---
+title: Fully qualify id columns for keyset pagination (Projects API)
+merge_request: 29026
+author:
+type: fixed

spec/finders/projects_finder_spec.rb

@@ -85,6 +85,24 @@ describe ProjectsFinder, :do_not_mock_admin_mode do
         end
       end
 
+      describe 'regression: Combination of id_before/id_after and joins requires fully qualified column names' do
+        context 'only returns projects with a project id less than given and matching search' do
+          subject { finder.execute.joins(:route) }
+
+          let(:params) { { id_before: public_project.id }}
+
+          it { is_expected.to eq([internal_project]) }
+        end
+
+        context 'only returns projects with a project id greater than given and matching search' do
+          subject { finder.execute.joins(:route) }
+
+          let(:params) { { id_after: internal_project.id }}
+
+          it { is_expected.to eq([public_project]) }
+        end
+      end
+
       describe 'filter by visibility_level' do
         before do
           private_project.add_maintainer(user)