When you message another Claude Code session through Remote Control, that session can now advertise whether it is able to receive cross-session messages at all. If it has not advertised that, the send no longer reads as a plain success: the model-facing result gains an explicit caveat and the on-screen result gains a short parenthetical, both saying the server accepted the message but delivery is unconfirmed because the other session may be running an older version that cannot receive it. The send itself still goes through.
- The model-facing result gains
; accepted by the server for that session, but delivery is not confirmed: it has not reported that it can receive cross-session messages and may be on an older version that cannot. - The displayed result gains
(accepted by the server; delivery not confirmed, that session may be on an older version). - When the other session does report that it can receive inbound cross-session messages, both added strings are empty and the result reads exactly as it did before.
- Applies to successful sends addressed with the
bridge:prefix. - Nothing gates this, no flag, setting or environment variable. The behaviour depends only on what the receiving session advertises.
- Neither string is present in 2.1.246.
delivery is not confirmed: it has not reported that it can receive cross-session messages, ; accepted by the server for that session, but delivery is not confirmed: it has not reported that it can receive cross-session messages and may be on an older version that cannot
Strings lifted out of the shipped bundle, so the claim above can be checked against them.