Source Intelligence

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

All of v2.1.238 Home All releases olderv2.1.237 v2.1.239newer
Claude Code v2.1.238

Messages to another session can be refused or dropped, with the reason stated

You'll notice
Useful3 Signal3
Cross-Session Messaging

Cross-session messages now say why they were refused or dropped, including the recipient having it off.

What

A cross-session message can now be turned down because the recipient has the feature off, reported as recipient_gate_off, alongside the existing refusal for elevated sessions. Sessions advertise this in their cloud listing, and the sender is told the target's Claude would never see it. Messages can also come back as dropped with a reason: rate-limited, duplicate, hop loop, hop runaway or queue full.

Details
  • The refusal text is "That session is not accepting cross-session messages (the feature is off there, or a setting or policy there refuses them); it was not delivered."; a shorter form goes back to the model.
  • Before dialling a peer, a lookup checks the listing for whether it accepts peer messages and refuses without opening a connection.
  • Drops print a warning and hand Claude a "[Cross-session delivery notice] Do not resend now:" note, so it does not retry on its own.
  • Rate-limit drops are reported as "sender exceeded the peer message rate limit"; drop receipts are batched with trailing coalescing and a per-window cap.
  • Nothing gates this on the sender's side; it follows what the recipient advertises.
Evidence

[Cross-session delivery notice] Do not resend now:, That session is not accepting cross-session messages (the feature is off there, or a setting or policy there refuses them); it was not delivered., sender exceeded the peer message rate limit

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

See this entry in the whole of v2.1.238 →