When submit cannot prove the pane's runtime owns the selected stored session
(reverse binding lost to eviction, reconnect, or a compression rotation the
selection never followed), it resumes the stored session and continues on
the runtime id that session.resume returns. That path pinned only
activeSessionIdRef. ChatView renders the $sessionStates slice named by
$activeSessionId, so the optimistic prompt, the reply, and every later turn
landed in a slice the pane never painted, while the legacy $messages mirror
(which the ref drives) looked correct. The chat stayed frozen until a relaunch.
Rebind the atom together with the ref, as the session-not-found recovery in
the same file already does, and carry the transcript the pane was showing
into the resumed runtime's empty slice (session.resume omits messages) when
both name the same conversation by lineage. A pane runtime that belongs to a
different stored session is never carried over.
Refs #71733
Refs #117867
8fb0fc6ae6