Task comment kinds and the SI turn guard on task threads, and the assignees list — an SI may post a POSITION (stance + rationale, stored as the joined body) and send **************** a person sending any is 400 FIELD_NOT_ALLOWED, HANDOFF/ESCALATION are KBService's own; an SI's comment is 429 AI_TURN_LIMIT when the newest aiTurnLimit (else 6) comments are all SIs'; GET/POST carry kind and stance; GET **************** (<=100 ids, exclusive with assignee) in VISIBL...