Claude Code Lightbulb Hooks

A Wipro/Tuya smart bulb wired into Claude Code hooks as an ambient status indicator. The bulb's color tells you what your session is doing without looking at the terminal — idle, working, or waiting on you for a permission decision.

Bulb used: Wipro NS9400 (Amazon.in).

light.py is the CLI that drives the bulb (cloud or local LAN). light-hook.sh is the wrapper Claude Code's hooks call into.

Notification fires for both "permission needed" and the idle "waiting for your input" ping. light-hook.sh notify reads the payload and picks white for the idle ping, red otherwise — so red always means act now.

Configured in ~/.claude/settings.json. Each event calls light-hook.sh <color>, which reads the hook's stdin JSON and skips the call if agent_id is present — meaning it's a subagent, not the main session. Without that guard, every background subagent spawn/exit would re-fire SessionStart/SessionEnd and stomp the light with the wrong color.

Hooks can also live in a repo's .claude/settings.json. That doesn't replace the user-level config — Claude Code merges hook lists across scopes, so a project-level PreToolUse hook runs alongside the one in ~/.claude/settings.json, not instead of it. Keep the light wiring in user settings (it's session-wide) and use project settings for repo-specific hooks.

"hooks": {
  "SessionStart": [{ "hooks": [
    { "type": "command", "command": "\"~/.claude/hooks/light-hook.sh\" white" }
  ]}],
  "UserPromptSubmit": [{ "hooks": [
    { "type": "command", "command": "\"~/.claude/hooks/light-hook.sh\" green" }
  ]}],
  "PreToolUse": [{ "hooks": [
    { "type": "command", "command": "\"~/.claude/hooks/light-hook.sh\" green" }
  ]}],
  "PostToolUse": [{ "hooks": [
    { "type": "command", "command": "\"~/.claude/hooks/light-hook.sh\" green" }
  ]}],
  "Notification": [{ "hooks": [
    { "type": "command", "command": "\"~/.claude/hooks/light-hook.sh\" notify" }
  ]}],
  "PermissionRequest": [{ "hooks": [
    { "type": "command", "command": "\"~/.claude/hooks/light-hook.sh\" red" }
  ]}],
  "Stop": [{ "hooks": [
    { "type": "command", "command": "\"~/.claude/hooks/light-hook.sh\" white" }
  ]}],
  "SessionEnd": [{ "hooks": [
    { "type": "command", "command": "\"~/.claude/hooks/light-hook.sh\" white" }
  ]}]
}

SessionEnd fires on /clear, /exit, logout, or any other session termination — wiring it to white means the bulb doesn't sit green/red after you've walked away from the session entirely.

UserPromptSubmit fires once when you hit enter; the next color event is Stop when the turn ends. Between those, a mid-turn Notification or PermissionRequest paints the bulb red.

The first fix attempt was PreToolUse alone, on the assumption it re-fires after you approve a permission prompt and resets the light. It doesn't — PreToolUse fires exactly once, before the permission check, not after you click "Yes". The real event order is PreToolUse (green) → PermissionRequest (red) → you approve → the tool just runs, with no hook event in between (Claude Code has no PermissionApproved hook). So the bulb stayed red until Stop, no matter how fast you approved.

PostToolUse fires right after a tool finishes executing, including the one you just approved — wiring it to green clears red the moment that tool completes instead of waiting for the whole turn to end. It's not literally instant on keypress (no hook exists for that), but it's the closest available signal.

This is the actual hooks block from a working setup, paths swapped for placeholders. Note some events run other, unrelated hooks (a mode-tracking plugin, an rtk wrapper) alongside the light call — hooks for the same event just run as a list, in order:

"hooks": {
  "SessionStart": [
    {
      "hooks": [
        {
          "type": "command",
          "command": "\"<path-to-node>\" \"~/.claude/hooks/some-other-hook.js\"",
          "timeout": 5,
          "statusMessage": "Running some other hook..."
        },
        {
          "type": "command",
          "command": "\"~/.claude/hooks/light-hook.sh\" white",
          "timeout": 10
        }
      ]
    }
  ],
  "UserPromptSubmit": [
    {
      "hooks": [
        {
          "type": "command",
          "command": "\"<path-to-node>\" \"~/.claude/hooks/some-other-hook.js\"",
          "timeout": 5,
          "statusMessage": "Running some other hook..."
        },
        {
          "type": "command",
          "command": "\"~/.claude/hooks/light-hook.sh\" green",
          "timeout": 10
        }
      ]
    }
  ],
  "PreToolUse": [
    {
      "matcher": "Bash",
      "hooks": [
        {
          "type": "command",
          "command": "rtk hook claude"
        }
      ]
    },
    {
      "matcher": "",
      "hooks": [
        {
          "type": "command",
          "command": "\"~/.claude/hooks/light-hook.sh\" green",
          "timeout": 10
        }
      ]
    }
  ],
  "Notification": [
    {
      "matcher": "",
      "hooks": [
        {
          "type": "command",
          "command": "\"~/.claude/hooks/light-hook.sh\" notify",
          "timeout": 10
        }
      ]
    }
  ],
  "PermissionRequest": [
    {
      "matcher": "",
      "hooks": [
        {
          "type": "command",
          "command": "\"~/.claude/hooks/light-hook.sh\" red",
          "timeout": 10
        }
      ]
    }
  ],
  "PostToolUse": [
    {
      "matcher": "",
      "hooks": [
        {
          "type": "command",
          "command": "\"~/.claude/hooks/light-hook.sh\" green",
          "timeout": 10
        }
      ]
    }
  ],
  "Stop": [
    {
      "matcher": "",
      "hooks": [
        {
          "type": "command",
          "command": "\"~/.claude/hooks/light-hook.sh\" white",
          "timeout": 10
        }
      ]
    }
  ],
  "SessionEnd": [
    {
      "matcher": "",
      "hooks": [
        {
          "type": "command",
          "command": "\"~/.claude/hooks/light-hook.sh\" white",
          "timeout": 10
        }
      ]
    }
  ]
}

light-hook.sh (10.10.10.100 is my bulbs local IP):

#!/usr/bin/env bash
set -euo pipefail
COLOR="$1"
INPUT="$(cat)"
AGENT_ID="$(echo "$INPUT" | jq -r '.agent_id // empty')"
if [ -n "$AGENT_ID" ]; then
  exit 0
fi

# "notify" decides from the payload: idle "waiting for your input"
# ping = white (session idle); anything else = red (act now).
if [ "$COLOR" = "notify" ]; then
  MESSAGE="$(echo "$INPUT" | jq -r '.message // empty')"
  case "$MESSAGE" in
    *"waiting for your input"*) COLOR="white" ;;
    *)                          COLOR="red" ;;
  esac
fi

cd /path/to/claude-lightbulb-hooks
exec python3 light.py -q --lan 10.10.10.100 -s on -C "$COLOR" -b 100

To wire a new event, add another block calling light-hook.sh <color>, or point it straight at light.py if you don't need the subagent guard.

pip install tinytuya

Copy light.json.example to light.json and fill in the fields:

cp light.json.example light.json

{
    "device_id": "your-device-id",
    "api_key": "your-tuya-access-id",
    "api_secret": "your-tuya-access-secret",
    "api_region": "in",
    "device_local_key": "your-local-key",
    "device_version": 3.3
}

light.json is gitignored — never commit it, it holds live credentials.

All fields can live in one config file — unused fields are ignored.

1. Go to iot.tuya.com, sign up, create a Cloud project
2. Cloud → your project → Devices → Add Device → paste device ID (from SmartLife app)
3. Device appears with full details including key (= device_local_key)
4. Note api_key and api_secret from project's Authorization page

Cloud mode works immediately. LAN mode also needs the bulb IP (use --lan <ip>).

python3 -m tinytuya scan listens for device broadcasts and reports each bulb's IP, device ID, local key, and protocol version — everything light.json needs for LAN mode, in one shot:

Smart light   Product ID = key4fv3xs8twchhy  [Valid Broadcast]:
    Address = 10.10.10.109   Device ID = 63076103...  Local Key = Mm!*...  Version = 3.1

Use the reported Version as device_version — guessing it is the most common LAN failure (see 904 below). The scan also writes snapshot.json; it's gitignored here since it contains the local key.

Useful for testing the bulb outside of hooks.

Works anywhere with internet — no need to be on same network as bulb.

# Status
python3 light.py

# Turn on/off
python3 light.py -s on
python3 light.py -s off

# Brightness (0-100%)
python3 light.py -s on -b 70

# Color
python3 light.py -s on -b 50 -C red
python3 light.py -C green
python3 light.py -C '#ff6600'

# Help
python3 light.py -h

Bulb must be on same local network. Faster — no internet round-trip.

python3 light.py --lan 192.168.1.100 -s on
python3 light.py --lan 192.168.1.100 -b 60 -C yellow
python3 light.py --lan 192.168.1.100 -s off

Finding your bulb's IP:

python3 -m tinytuya scan   # best — reports IP, version, and local key
arp -a | grep esp          # fallback
# or check router's DHCP client list for MAC matching device_id suffix

python3 light.py -c /path/to/config.json -s on

Hex accepted: #ff0000, #f00, #00ff00, etc.

Cloud: "permission deny" (1106) — device not linked to cloud project. Go to iot.tuya.com → Devices → Add Device → enter device ID.

LAN: "Unable to Connect" (901) — bulb not reachable. Check IP, network isolation, or Wi-Fi client isolation on your router. Fall back to cloud mode.

LAN: "Unexpected Payload from Device" (904) — wrong device_version. The bulb decrypts your request but rejects the framing (tinytuya debug shows a plaintext data format error reply). Run python3 -m tinytuya scan and set device_version to the version it reports. Older Wipro firmware is 3.1, not the default 3.3.

LAN: "Check device key or version" (914) — version is right but the local key is wrong (or vice versa). Re-pull the key from iot.tuya.com; re-pairing the bulb rotates it.

Light doesn't match session state / flickers to wrong color — check whether a subagent fired the hook. light-hook.sh should skip when agent_id is present in stdin JSON; if it's not skipping, verify jq is installed and on PATH.

Light stuck red while Claude is clearly working — you're missing the PostToolUse → green wiring. PreToolUse alone won't fix this: it fires once, before a permission prompt, not after you approve it. Add the PostToolUse block (see Why both PreToolUse and PostToolUse are needed).

• Claude Code hooks docs