Brings A3's parts receiver and bus adapters, the shared caller lists and builder versions question, a transfer read back from bus state (0424e87) and catalogue.SeatReference (c10ef07).c974a11adds nothing: its version_numbered.go and BuildAnswer.OutOfStep are the join's own. publish stays out (ADR 0627,1a149d4): packages_list_test keeps the join's form. TestAHolderTakesAFileInParts is a subtest of TestAFileTravelsInTheParts, so unit tests stay at 476. Claude-Session: https://claude.ai/code/session_01JG73KJNrH5EgFXMKKYSrig