-- Knowledge Platform schema migration
-- Migration id: 0053_answer_trace_source
-- Dialect: tidb
-- Answer traces record which caller produced them (console retrieval test, workflow node, service
-- API, agent, MCP) so retrieval history can distinguish and filter them. NULL means retrieval_test.

ALTER TABLE `answer_traces`
  ADD COLUMN IF NOT EXISTS `source` VARCHAR(32) NULL;

CREATE INDEX IF NOT EXISTS `answer_traces_space_source_created_idx`
  ON `answer_traces` (`knowledge_space_id`, `source`, `created_at`, `id`);