fix(captain): require iterative vector scans

db/migrate/20260714230000_replace_captain_assistant_response_embedding_index_with_cosine.rb

@@ -3,8 +3,11 @@ class ReplaceCaptainAssistantResponseEmbeddingIndexWithCosine < ActiveRecord::Mi
 
   OLD_INDEX_NAME = 'vector_idx_knowledge_entries_embedding'.freeze
   NEW_INDEX_NAME = 'vector_idx_captain_assistant_responses_embedding_cosine'.freeze
+  MINIMUM_PGVECTOR_VERSION = Gem::Version.new('0.8.0')
 
   def up
+    ensure_iterative_scans_supported!
+
     add_index :captain_assistant_responses,
               :embedding,
               using: :ivfflat,
@@ -23,4 +26,13 @@ class ReplaceCaptainAssistantResponseEmbeddingIndexWithCosine < ActiveRecord::Mi
               algorithm: :concurrently
     remove_index :captain_assistant_responses, name: NEW_INDEX_NAME, algorithm: :concurrently
   end
+
+  private
+
+  def ensure_iterative_scans_supported!
+    installed_version = Gem::Version.new(select_value("SELECT extversion FROM pg_extension WHERE extname = 'vector'"))
+    return if installed_version >= MINIMUM_PGVECTOR_VERSION
+
+    raise StandardError, "pgvector #{MINIMUM_PGVECTOR_VERSION} or newer is required for filtered FAQ search"
+  end
 end