-- 0. 公共
-- 来源：docs/architecture/schema-draft.sql（2026-11-03 验证过的草案）
CREATE SCHEMA IF NOT EXISTS app;

-- 当前事务的租户；api / worker 在事务开始时 SET LOCAL app.tenant_id
CREATE FUNCTION current_tenant() RETURNS uuid
LANGUAGE sql STABLE AS $$
  SELECT nullif(current_setting('app.tenant_id', true), '')::uuid
$$;

CREATE FUNCTION set_updated_at() RETURNS trigger
LANGUAGE plpgsql AS $$
BEGIN
  NEW.updated_at := now();
  RETURN NEW;
END $$;

-- 只追加表：禁止 UPDATE / DELETE
CREATE FUNCTION forbid_change() RETURNS trigger
LANGUAGE plpgsql AS $$
BEGIN
  RAISE EXCEPTION '% is append-only', TG_TABLE_NAME;
END $$;