-- 380_clause_study.sql — 절-문서 공부도구(노트/형광펜/암기카드) 저장. FK 없음(documents 락 회피).
CREATE TABLE IF NOT EXISTS clause_study (
  id         bigserial PRIMARY KEY,
  doc_id     bigint NOT NULL,
  kind       text   NOT NULL,            -- 'note' | 'highlight' | 'card'
  payload    jsonb  NOT NULL DEFAULT '{}',
  created_at timestamptz NOT NULL DEFAULT now()
);
CREATE INDEX IF NOT EXISTS idx_clause_study_doc ON clause_study(doc_id, kind);