DELETE /rigshare/api/chat (admin) empties chat.jsonl, tells every client to
clear its history, then posts a notice saying who cleared it. Admin tab gets
a Chat section with a confirmed Clear chat history button.
Chat is an append-only chat.jsonl paged by sequence number: the welcome
carries the latest 50 messages and GET /rigshare/api/chat pages further back.
The panel loads older pages as you scroll up, keeps your place, and adds date
dividers. ComfyUI reuses one slot element between custom sidebar tabs, so
each tab now replaces the slot's content instead of appending to it.
Edouard Durand