Message your other Claude Code sessions changedcross-session-messaging
Nearest release: v2.1.250, published an hour before this site recorded the change. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.
Recorded here
Lines+6added
Lines−2removed
From line
8
where the diff opens
First seen
14 Aug 2026
this site's first read of the page
Recorded edits28to this page, all time
The whole hunk
from line 8, old and new numbered
/
from line 8
88
99Cross-session messaging lets Claude deliver a message from one of your Claude Code sessions to another. When a change in one session breaks what another is building on, Claude can warn that session before you notice. When one session settles a question another is blocked on, Claude can send the answer across.
1010
11A message is a piece of text one Claude writes to another, never conversation history or files. To move a whole conversation or its context, [resume the session](/docs/en/sessions#resume-a-session) instead.
11A message is a piece of text one Claude writes to another, never the sender's conversation history or files. To move a whole conversation or its context, [resume the session](/docs/en/sessions#resume-a-session) instead.
1212
1313Claude uses two tools for this: `ListAgents` to discover which agents it can reach, and `SendMessage` to deliver a message to one of them by name. With the same `SendMessage` tool, Claude can also message [subagents](/docs/en/sub-agents#resume-subagents) and [agent team](/docs/en/agent-teams) teammates within a single session or team. This page covers messages between your independent sessions.
1414
from line 59
5959
6060The receiving Claude reads the message between tool calls during an active turn, so a running tool is never interrupted. When the receiving session is idle, Claude Code starts a new turn with the message.
6161
62When a message that starts a new turn mentions a file as an `@` immediately followed by its path, Claude Code [attaches that file](/docs/en/common-workflows#reference-files-and-directories) as it exists on the receiving machine, resolving a relative path from the receiving session's working directory. The receiving session's [`Read` deny rules](/docs/en/permissions#read-and-edit) apply to that file, as they do to a file you mention with `@` yourself. When such a message mentions an [MCP resource](/docs/en/mcp#use-mcp-resources) with `@`, Claude Code attaches that resource from the receiving session's MCP servers. A path written without the `@` stays plain text and attaches nothing.
63
64A message that Claude reads during an active turn arrives as plain text with nothing attached, even if it mentions files or MCP resources with `@`.
65
6266Claude Code refuses a message in the following cases:
6367
6468* The message is [over the size cap](#limitations). Claude Code refuses it in the sending session, before it leaves.
from line 178
174178
175179The preview shortens only what you see. Whether or not you expand it, Claude reads the full message.
176180
177Claude receives the message with the sender's name and a reply address, except for a [one-way cross-machine message](#message-sessions-on-other-machines), which carries no reply address. Beyond the name and reply address, the receiving Claude gets only the message's text, never the sender's conversation history or files.
181Claude receives the message with the sender's name and a reply address, except for a [one-way cross-machine message](#message-sessions-on-other-machines), which carries no reply address. Beyond the name and reply address, the receiving Claude gets the message's text, never the sender's conversation history or files. An `@` mention in the text can still attach a file or MCP resource on the receiving side, as described under [Message delivery](#message-delivery).
178182
179183This example is a message one Claude wrote to another, as its full text reads when you expand it:
180184
No line in this hunk matches that.