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Sweep 22 Oct 2026 · 04:32Z Build v2.1.308 527 read Stable v2.1.308 Latest v2.1.308 Next v2.1.308 Feeds RSS JSON llms.txt llms-full.txt Unofficial
HomeReleasesv2.1.251entry #21

Claude Code v2.1.251 ·

SendMessage can deliver to Claude Desktop sessions

SendMessage can now deliver plain text to Claude Desktop sessions.

Use it now Notable New Features
JSON All of v2.1.251
Use it nowTier: how much it should matter to you
3Useful: my rating, 1 to 5
4Signal: worth watching, 1 to 5
MessagingArea: what it touches
New FeaturesKind: in v2.1.251,
What probably matters to youSection of the release
What

SendMessage now recognises targets that look like Claude Desktop session ids and delivers plain-text messages to them through Claude Desktop itself, alongside the existing local-socket and remote-bridge delivery paths.

Details
  • Requires Claude Desktop's own session messaging tool to be present in the session; without it the send fails as not reachable, with the message quoted below.
  • Has its own guards for empty messages and for "hop loops", where agents keep messaging each other automatically, separate from the guards on the other delivery paths.
Evidence

Claude Desktop's session messaging tool is not available in this session, so SendMessage cannot deliver to it

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

Read from
Names in the bundleSendMessage
Since it was published

The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.

Added since A small documentation edit on Create custom subagents touched a line naming SendMessage after this was published. The second filter applies to subagents running in the background. Apart from `Agent` and `ExitPlanMode`, which follow the first filter's conditions wherever the subagent runs, a background subagent keeps every MCP tool but only these built… sub-agents see the edit
Confirmed since Anthropic's documentation has since written up SendMessage, on Claude Code changelog. * Fixed cross-session messages held by the receiving session's permission-mode policy leaving no trace: headless senders now get a delivery notice, and `SendMessage` results no longer imply it was read changelog see the edit
How sure we are
Two sources agreeTwo things we can check say the same as this entry.
Anthropic's documentation agreesAnthropic's documentation has since written up SendMessage, on Claude Code changelog.
Anthropic's release notes agreeFixed replying to a message Claude Desktop delivered from another session: SendMessage to that session id now delivers through Claude…

See this entry in the whole of v2.1.251 →

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