-- 审计日志只读不可删；user_id 指向系统库 users，跨库不能建外键。
CREATE TABLE IF NOT EXISTS audit_logs (
    id          INTEGER PRIMARY KEY AUTOINCREMENT,
    user_id     INTEGER,
    action      TEXT NOT NULL,
    entity_type TEXT,
    entity_id   INTEGER,
    before_json TEXT,
    after_json  TEXT,
    ip          TEXT,
    request_id  TEXT,
    created_at  TEXT NOT NULL DEFAULT (datetime('now'))
);

CREATE INDEX IF NOT EXISTS idx_audit_logs_user_id ON audit_logs(user_id);
CREATE INDEX IF NOT EXISTS idx_audit_logs_entity ON audit_logs(entity_type, entity_id);
CREATE INDEX IF NOT EXISTS idx_audit_logs_created_at ON audit_logs(created_at);