AI user input notification light

Smart and stylish notification light

Introduction

When an AI client like Claude Code or Codex runs for a while, it sometimes needs user input before it can continue. That is easy to miss when the terminal is not in front of you, or when you run multiple clients at once.

I first solved this with a sound and a popup notification on my screen. Since I already had a smart notification light on my desk, I extended the setup to alert me with a visual trigger as well.

The light itself is an earlier project, described on the Smart and stylish notification light page. That page explains how to build it with a GU10 smart bulb in a stylish pencil holder.

An automation to trigger the light was already in place, so this is only a small update. The missing link was sending an MQTT message to a specific topic from the AI client through a hook whenever it needs user input. Node-RED listens to that topic and turns the smart notification light blue for 5 seconds when an AI client needs attention.

Smart notification light changing colors
The same smart notification light can be reused for Claude Code and Codex alerts.

What it does
What you need
Install MQTT client
Create the MQTT script
Add AI hooks
- Claude Code hooks
- Codex hooks
Create the Node-RED flow
Test the notification

What it does

Claude Code and Codex support hooks that run commands when certain events happen. This example uses those hooks to publish a small MQTT message.

The flow is:

Claude Code or Codex needs attention.
A hook runs ~/mqtt_ai_agent.sh.
The script publishes a message to the MQTT topic ai-agent.
Node-RED listens to that topic.
Node-RED turns the smart light blue.
After 5 seconds, Node-RED turns the light off again.

This is useful for:

a permission request;
a user input question;
a Claude Code or Codex stop event;
any other hook you want to make visible in the room.

What you need

For this setup you need:

Claude Code or Codex installed on your computer.
An MQTT broker, for example the MQTT broker used by Home Assistant.
mosquitto_pub installed on the computer where Claude Code or Codex runs.
Node-RED connected to the same MQTT broker.
A smart light that Node-RED can control.

If you still need to build the light, first follow this project:

Smart and stylish notification light

Install MQTT client

Install Mosquitto so the hook script can publish MQTT messages.

On macOS, install it with Homebrew:

brew install mosquitto

After installing, check that mosquitto_pub is available:

mosquitto_pub --help

Create the MQTT script

Create the file ~/mqtt_ai_agent.sh.

#!/usr/bin/env bash

HOOK="${1:-user-input}"

mosquitto_pub \
    -h "192.168.x.x" \
    -p 1883 \
    -u "username" \
    -P "password" \
    -t "ai-agent" \
    -m '{"hook":"'"$HOOK"'"}'

Change these values:

192.168.x.x: the IP address of your MQTT broker.
username: your MQTT username.
password: your MQTT password.
ai-agent: the MQTT topic, if you want to use another topic name.

Make the script executable:

chmod +x ~/mqtt_ai_agent.sh

You can test it manually:

~/mqtt_ai_agent.sh permission

This should publish this MQTT message:

{
  "hook": "permission"
}

Add AI hooks

Claude Code hooks

Open the Claude Code settings file:

~/.claude/settings.json

Add these hooks:

{
  "hooks": {
    "Stop": [
      {
        "hooks": [{ "type": "command", "command": "~/mqtt_ai_agent.sh stop" }]
      }
    ],
    "PermissionRequest": [
      {
        "hooks": [{ "type": "command", "command": "~/mqtt_ai_agent.sh permission" }]
      }
    ],
    "PreToolUse": [
      {
        "matcher": "AskUserQuestion",
        "hooks": [{ "type": "command", "command": "~/mqtt_ai_agent.sh ask-user-question" }]
      }
    ]
  }
}

The most useful one for me is PermissionRequest. When Claude Code asks for approval, the light flashes blue so I know it is waiting for me.

Codex hooks

Codex can also run lifecycle hooks. Use these if you want the same notification light for Codex approval requests, or for when a Codex turn finishes.

Create or edit this file:

~/.codex/hooks.json

Add these hooks:

{
  "hooks": {
    "PermissionRequest": [
      {
        "hooks": [
          {
            "type": "command",
            "command": "~/mqtt_ai_agent.sh codex-permission",
            "statusMessage": "Sending Codex permission notification"
          }
        ]
      }
    ],
    "Stop": [
      {
        "hooks": [
          {
            "type": "command",
            "command": "~/mqtt_ai_agent.sh codex-stop",
            "statusMessage": "Sending Codex stop notification"
          }
        ]
      }
    ]
  }
}

The PermissionRequest hook is the useful one: it triggers when Codex asks before running a command or tool. The Stop hook runs when a Codex turn stops, which is handy if you want a signal when Codex is done and waiting for the next prompt.

After adding or changing Codex hooks, open Codex and run:

/hooks

Review and trust the new hook. Codex skips unmanaged command hooks until they are trusted.

If you prefer to define hooks in ~/.codex/config.toml, the same setup can also be written inline:

[[hooks.PermissionRequest]]

[[hooks.PermissionRequest.hooks]]
type = "command"
command = "~/mqtt_ai_agent.sh codex-permission"
statusMessage = "Sending Codex permission notification"

[[hooks.Stop]]

[[hooks.Stop.hooks]]
type = "command"
command = "~/mqtt_ai_agent.sh codex-stop"
statusMessage = "Sending Codex stop notification"

Use either ~/.codex/hooks.json or inline hooks in ~/.codex/config.toml, not both. Defining both in the same config layer works, but Codex will warn about it.

Create the Node-RED flow

In Node-RED, create a flow that listens to the MQTT topic ai-agent.

The basic flow is:

MQTT-in node subscribes to ai-agent.
JSON node parses the message.
Switch node checks the hook value, for example permission, codex-permission, or codex-stop.
Call service node turns the smart light on in blue.
Delay node waits 5 seconds.
Call service node turns the smart light off.

The light service call in Home Assistant can use a blue RGB value:

service: light.turn_on
target:
  entity_id: light.notification_light
data:
  rgb_color:
    - 0
    - 80
    - 255
  brightness_pct: 100

After 5 seconds, turn it off:

service: light.turn_off
target:
  entity_id: light.notification_light

Replace light.notification_light with your own light entity.

The Node-RED flow from the smart notification light project can be reused as a starting point.

Test the notification

Run the script manually:

~/mqtt_ai_agent.sh permission

If everything is connected correctly, Node-RED receives the MQTT message and the smart notification light turns blue for 5 seconds.

After that, use Claude Code as normal. When it asks for permission or needs user input, the light notification triggers automatically.

For Codex, run:

~/mqtt_ai_agent.sh codex-permission

If that works, start Codex and trust the hook with /hooks. The notification then triggers when Codex asks for permission, and optionally when a turn stops if you kept the Stop hook.

The smart light can do more than signal Claude Code and Codex. I also use it for other Home Assistant automations, such as CO2 warnings. The full build is here: Smart and stylish notification light.

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vd Brink Home Automations

Home automations with Home Assistant, ESPHome, Node-RED and more tech