You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
ArtifactsArea: what it touches
In DevelopmentKind: in v2.1.232,
In DevelopmentSection of the release
What
If a comment thread was summoned or activated by a different person's Claude session, the reply is now refused with a specific outcome, and the model is told the draft was discarded and not to retry rather than being left to guess.
Details
A 403 identifying a foreign sender maps to a summon_foreign outcome, which is also an optional field on the reply schema.
Telemetry gains summon_foreign_sender, summon_foreign_notice_suppressed and edit_reply_summon_foreign.
Part of the artifact comments feature, which is itself behind remote-config gates, so whether you see it depends on server configuration.
Evidence
summon_foreign_sender, reply not posted (another user's summon or activation)
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
