cmux/docs/notifications.md

Notifications

cmux provides a notification panel for AI agents like Claude Code, Codex, and OpenCode. Notifications appear in a dedicated panel and trigger macOS system notifications.

Quick Start

# Send a notification (if cmux is available)
command -v cmux &>/dev/null && cmux notify --title "Done" --body "Task complete"

# With fallback to macOS notifications
command -v cmux &>/dev/null && cmux notify --title "Done" --body "Task complete" || osascript -e 'display notification "Task complete" with title "Done"'

Detection

Check if cmux CLI is available before using it:

# Shell
if command -v cmux &>/dev/null; then
    cmux notify --title "Hello"
fi

# One-liner with fallback
command -v cmux &>/dev/null && cmux notify --title "Hello" || osascript -e 'display notification "" with title "Hello"'

# Python
import shutil
import subprocess

def notify(title: str, body: str = ""):
    if shutil.which("cmux"):
        subprocess.run(["cmux", "notify", "--title", title, "--body", body])
    else:
        # Fallback to macOS
        subprocess.run(["osascript", "-e", f'display notification "{body}" with title "{title}"'])

CLI Usage

# Simple notification
cmux notify --title "Build Complete"

# With subtitle and body
cmux notify --title "Claude Code" --subtitle "Permission" --body "Approval needed"

# Notify specific tab/panel
cmux notify --title "Done" --tab 0 --panel 1

Integration Examples

Claude Code Hooks

Add to ~/.claude/settings.json:

{
  "hooks": {
    "Notification": [
      {
        "matcher": "idle_prompt",
        "hooks": [
          {
            "type": "command",
            "command": "command -v cmux &>/dev/null && cmux notify --title 'Claude Code' --body 'Waiting for input' || osascript -e 'display notification \"Waiting for input\" with title \"Claude Code\"'"
          }
        ]
      },
      {
        "matcher": "permission_prompt",
        "hooks": [
          {
            "type": "command",
            "command": "command -v cmux &>/dev/null && cmux notify --title 'Claude Code' --subtitle 'Permission' --body 'Approval needed' || osascript -e 'display notification \"Approval needed\" with title \"Claude Code\"'"
          }
        ]
      }
    ]
  }
}

OpenAI Codex

Add to ~/.codex/config.toml:

notify = ["bash", "-c", "command -v cmux &>/dev/null && cmux notify --title Codex --body \"$(echo $1 | jq -r '.\"last-assistant-message\" // \"Turn complete\"' 2>/dev/null | head -c 100)\" || osascript -e 'display notification \"Turn complete\" with title \"Codex\"'", "--"]

Or create a simple script ~/.local/bin/codex-notify.sh:

#!/bin/bash
MSG=$(echo "$1" | jq -r '."last-assistant-message" // "Turn complete"' 2>/dev/null | head -c 100)
command -v cmux &>/dev/null && cmux notify --title "Codex" --body "$MSG" || osascript -e "display notification \"$MSG\" with title \"Codex\""

Then use:

notify = ["bash", "~/.local/bin/codex-notify.sh"]

OpenCode Plugin

Create .opencode/plugins/cmux-notify.js:

export const CmuxNotificationPlugin = async ({ $, }) => {
  const notify = async (title, body) => {
    try {
      await $`command -v cmux && cmux notify --title ${title} --body ${body}`;
    } catch {
      await $`osascript -e ${"display notification \"" + body + "\" with title \"" + title + "\""}`;
    }
  };

  return {
    event: async ({ event }) => {
      if (event.type === "session.idle") {
        await notify("OpenCode", "Session idle");
      }
    },
  };
};

Environment Variables

cmux sets these in child shells:

Variable	Description
CMUX_SOCKET_PATH	Path to control socket
CMUX_TAB_ID	UUID of the current tab
CMUX_PANEL_ID	UUID of the current panel

CLI Commands

cmux notify --title <text> [--subtitle <text>] [--body <text>] [--tab <id|index>] [--panel <id|index>]
cmux list-notifications
cmux clear-notifications
cmux ping

Best Practices

1. Always check availability first - Use command -v cmux before calling
2. Provide fallbacks - Use || osascript for macOS fallback
3. Keep notifications concise - Title should be brief, use body for details