- client.py: inherit crawler_core.http_client.HTTPClient, use crawler_core.boss.sign.BossSign - api.py: use crawler_core.base.Result/BaseFetcher/BaseSearcher, fix self._http -> self.http_client - main.py: import BaseFetcher/BaseSearcher and BossSign from crawler_core - sign.py: replace with backward-compat stub re-exporting BossSign from crawler_core Satisfies ARCH-03