Agent Communication

Send messages to and read output from other tmux sessions running Claude Code or Codex. Built for coordination between parallel agent sessions.

Platform Support

Works identically on both platforms -- the underlying mechanism is tmux, not the AI agent. Sessions can communicate across platforms (a Claude Code session can message a Codex session and vice versa).

Setup

Make the script executable (one-time):

chmod +x ~/.claude/skills/agent-comms/scripts/agent-msg

Message Format

Always prefix messages with a header so the receiving session knows it's agent-to-agent:

[AGENT-MSG] From: <your-session-name>
<your actual message here>

Get your session name:

tmux display-message -p '#S'

Commands

SCRIPT=~/.claude/skills/agent-comms/scripts/agent-msg

# List available sessions
$SCRIPT list

# Send message (types into their terminal + Enter)
$SCRIPT send <session> "<message>"

# Read their terminal output
$SCRIPT read <session> --lines 50

# Get their working directory
$SCRIPT info <session>

Workflow

1. Get your session name for identification:

   tmux display-message -p '#S'

2. List sessions to find the target:

   ~/.claude/skills/agent-comms/scripts/agent-msg list

3. Read their context before sending:

   ~/.claude/skills/agent-comms/scripts/agent-msg read worker-1 --lines 50

4. Send your message with identification:

   ~/.claude/skills/agent-comms/scripts/agent-msg send worker-1 "[AGENT-MSG] From: main-session
   
   Hit a wall on the websocket reconnection logic. Here's where I'm stuck: [detailed context...]"

5. Read their response:

   ~/.claude/skills/agent-comms/scripts/agent-msg read worker-1 --lines 30

Example: Complex Debug Handoff

You've been debugging a native module issue for 20 minutes. It's a multi-layered problem involving Node versions, native rebuilds, and cross-project dependencies. You want another agent to take a look with full context:

# Check what sessions are running
~/.claude/skills/agent-comms/scripts/agent-msg list
# SESSION                  WINDOWS  ATTACHED
# worker-debug             1        no
# main-session             1        yes

# Send the full technical context
~/.claude/skills/agent-comms/scripts/agent-msg send worker-debug "[AGENT-MSG] From: main-session

Need a second opinion on a native module conflict. Here's what I've traced:

THE ISSUE:
- electron-builder fails with 'better-sqlite3 was compiled against a different Node.js version'
- This started after I ran nvm use 22 in another terminal for a different project

WHAT I'VE FOUND:
1. Main project expects Node 20.x for native modules
2. better-sqlite3 got rebuilt against Node 22 when I ran npm install in the other project
3. They share a global .node-gyp cache at ~/.node-gyp
4. The rebuild pulled in headers for 22.x, now electron can't load the module

WHAT I'VE TRIED:
- npm rebuild better-sqlite3 (still uses cached 22.x headers)
- Deleted node_modules, fresh install (same issue)
- electron-rebuild --force (fails with same ABI mismatch)

QUESTION:
Do I need to clear the global .node-gyp cache? Or is there a way to force better-sqlite3 to rebuild with electron's Node headers specifically? Wondering if I'm missing something obvious."

# Wait for them to analyze, then check response
~/.claude/skills/agent-comms/scripts/agent-msg read worker-debug --lines 50

When to Use This

• Complex debugging: You've built up 15 minutes of context tracing an issue - share it rather than have another agent start from scratch
• Cross-project conflicts: Version mismatches, shared caches, native module issues that span multiple repos
• Architectural decisions: "Here's the tradeoff I'm seeing between approach A and B, with all the constraints I've discovered"
• Rubber duck with context: Sometimes you just need another agent to see your full reasoning and spot the flaw

Why the Header Matters

The receiving session sees your message as user input. Without the [AGENT-MSG] header, it might think a human is typing. The header tells it:

• This is automated agent-to-agent communication
• Which session sent it (for replies)

Notes

• Session names follow patterns like terminal-HHMMSS or custom names you assign
• Always include the [AGENT-MSG] prefix
• Be specific about what you need
• The other agent can reply using the same skill