The co-keyed readers of `room.sessions` had to follow session identity or
they would split from it: the stop interrupt targeted a member's only
session regardless of which thread issued the stop, and the stranded-reply
harvest resumed by bare member key even though its marker already carries
`{before, thread}`.
The clarify mirror moves too — with per-thread sessions one member can be
blocked in two threads at once, and a room-and-member key let thread B's
question silently replace thread A's card. The sweep's owner lookup stays
a MEMBER question, so it reads the member half of the key and keeps the
`::` source-qualifier check on that half alone.
Co-authored-by: Wenfengcheng <30426178+Wenfengcheng@users.noreply.github.com>
Austin Pickett
1ce9733113