t9-ipc

한국어 README

Two or more Claude Code sessions. Talking to each other. In 5 minutes.

Running multiple Claude Code sessions at once? They can't see each other by default. This gives them a tiny shared mailbox so they can.

Session A                    Session B
  "hey B, I'm done"  ────►  "A is done, my turn"

What it does

• Discovery — who else is running right now?
• Direct messages — one session to another
• Broadcast — shout to everyone
• Real-time delivery — messages pop into the other session's conversation automatically (via Claude's MCP Channels)

That's it. No accounts, no servers, no npm install. Python standard library only.

5-minute setup

1. Clone

git clone https://github.com/HanbeenMoon/t9-ipc.git
cd t9-ipc

2. Point Claude Code at it

Open (or create) ~/.claude.json and add:

{
  "mcpServers": {
    "t9-ipc": {
      "command": "python3",
      "args": ["mcp/server.py"],
      "cwd": "/absolute/path/to/t9-ipc"
    }
  }
}

Replace /absolute/path/to/t9-ipc with wherever you cloned it.

3. Restart Claude Code

You're done. Open two sessions and ask one of them:

who else is online?

It will call t9_ipc_who and list the other session. Then:

send "hello" to <the other session id>

Messages from other sessions show up automatically in your conversation — tagged with <channel source="t9-ipc">.

The tools Claude gets

Tool	What it does
t9_ipc_who	List currently active sessions
t9_ipc_send	Send a message to a specific session
t9_ipc_broadcast	Send to everyone
t9_ipc_unread	List unread messages (fallback, for clients without Channels)
t9_ipc_set_name	Give this session a readable name

You never call these yourself — Claude does, when you ask things like "tell the other session to wait" or "who else is running?".

Is this for me?

• You run 2+ Claude Code sessions at once and want them to coordinate
• You want something tiny you can read in 20 minutes and trust
• You don't want to install a runtime, a package manager, or a server

Deliberately small and sharp. Four files, one MCP server, no configuration required.

How it works (if you're curious)

Three moving parts, that's it:

1. data/ipc/heartbeats.json — every live session pings this file every tool call. Dead sessions get cleaned automatically.
2. data/ipc/inbox/*.md — each message is a markdown file with a little YAML header. The files are the mailbox. No database required for the protocol.
3. mcp/server.py — a tiny MCP server that watches the inbox and pushes new files to Claude as they arrive.

Messages look like this:

---
from: session_alpha
to: session_beta
subject: status update
created: 2026-04-06 15:30:00
---

done with the parser, pushing to main

You can read them with your eyes. You can grep them. If the server crashes, your messages are still there.

Configuration (optional)

All optional. Defaults work out of the box.

Environment variable	What it does
IPC_SESSION_ID	Override the auto-generated session name
IPC_DB_PATH	Move the SQLite cache somewhere else
IPC_TG_TOKEN + IPC_TG_CHAT	Forward escalation-type messages to a Telegram bot

Platform support

Linux, macOS, and WSL. Not native Windows — the locking uses fcntl, which is Unix-only.

Credits

Respect to @devindown and TAP.

License

MIT