Fix similar_to vector query ordering for large libraries

app/controllers/base_documents_controller.rb

@@ -61,8 +61,8 @@ def index
       # Get similar documents but preserve existing filters
       @documents = @documents.related_by_embedding(embedding)
 
-      # Sort by neighbor_distance using SQL to maintain ActiveRecord relation
-      @documents = @documents.order('neighbor_distance ASC')
+      # Force pure distance ordering to keep nearest-neighbor queries index-friendly.
+      @documents = @documents.reorder('neighbor_distance ASC')
     else
       # Only apply default sorting if not doing similarity search
       @documents = if params[:sort] == 'questions'

app/models/document.rb

@@ -82,8 +82,7 @@ def unique_viewers
   # Because of the ordering, having too many documents may cause the most relevant documents to be lost.
   scope :related_by_embedding, lambda { |embedding, limit = nil|
     limit ||= ENV.fetch('RELATED_DOCUMENTS_LIMIT', 25).to_i
-    scope = nearest_neighbors(:embedding, embedding, distance: 'euclidean')
-    scope.order(updated_at: :desc).limit(limit)
+    nearest_neighbors(:embedding, embedding, distance: 'euclidean').limit(limit)
   }
 
   # Default scope to only show non-deleted documents