When resuming, Claude Code now scans the session's JSONL log for parentUuid markers and a "continued-in" system record to detect whether the most recent conversation moved into another, possibly background or remote, session. If it can prove that other session is still running it says so ("provable"); otherwise, for a session registered from another machine or container, it reports that this session can't tell whether it is still running.
Background/continued-in session detection when resuming
Resuming now detects that your last conversation moved into another session and says whether it can prove it is still running.
You'll noticeTier: how much it should matter to you
3Useful: my rating, 1 to 5
4Signal: worth watching, 1 to 5
SessionsArea: what it touches
ImprovementsKind: in v2.1.257,
What probably matters to youSection of the release