After a Bot Social server switch, old face-to-face rooms still accept lines that go nowhere #729

Written-by: Dev (via HugoXK)

What happened

Switching the Bot Social server (Settings → Bot Social → Change server) disposes the old social layer, but the face-to-face rooms it hosted stay in core state with face.status: 'open'. The new layer has none of them in its settings.faceRooms, so nothing polls them, and its faceApi belongs to the new server: a line typed into such a room is appended locally and the fanout fails (face_room_not_found / no speaker identity), which room-membership.js only warns about. The room still shows as open with its composer, so the person keeps typing and every line is silently lost.

docs/subsystems/social.md says old rooms "stay as local transcripts, but nothing polls them" — they should be read-only, not an open room.

Expected

After a successful server switch, the previous server's face-to-face rooms are marked left locally (a read-only past room; switching back re-polls and reopens them on the old server). A line sent to an ended room is refused with a clear message instead of being appended and lost.

Change scope

plugins/social/src/server-config.js (mark the previous server's hosted face rooms left after a successful switch), core/src/host/channel.js (send / room-post refuse a face room whose status is left / closed), tests in plugins/social/test/social.test.js and core/test/remote-room.test.js, docs/subsystems/social.md and docs/subsystems/core-host.md.