HA Lights sync

ha_lights_sync.yaml

blueprint:
  name: Master Light Sync
  description: >-
    Syncs power state, brightness, and color temperature from a single master light
    to one or more follower lights. Only the master triggers updates — changes to
    followers do not propagate back.
  domain: automation
  homeassistant:
    min_version: 2024.10.0
  input:
    master_light:
      name: Master Light
      description: The light that controls the followers.
      selector:
        entity:
          filter:
            - domain: light
    follower_lights:
      name: Follower Lights
      description: Lights that will mirror the master light's state.
      selector:
        entity:
          filter:
            - domain: light
          multiple: true
    transition_time:
      name: Transition Time
      description: Transition duration in seconds when syncing changes.
      default: 0.5
      selector:
        number:
          min: 0
          max: 10
          step: 0.1
          unit_of_measurement: seconds

mode: queued
max: 2

triggers:
  - trigger: state
    entity_id: !input master_light

variables:
  master: !input master_light
  followers: !input follower_lights
  transition: !input transition_time

conditions:
  # Only proceed if the state actually changed (not just attribute update with same values)
  - condition: template
    value_template: >-
      {{ trigger.from_state is not none and 
         (trigger.to_state.state != trigger.from_state.state or
          trigger.to_state.attributes.get('brightness') != trigger.from_state.attributes.get('brightness') or
          trigger.to_state.attributes.get('color_temp') != trigger.from_state.attributes.get('color_temp') or
          trigger.to_state.attributes.get('color_temp_kelvin') != trigger.from_state.attributes.get('color_temp_kelvin')) }}

actions:
  - choose:
      # Master turned off
      - conditions:
          - condition: template
            value_template: "{{ trigger.to_state.state == 'off' }}"
        sequence:
          - action: light.turn_off
            target:
              entity_id: "{{ followers }}"
            data:
              transition: "{{ transition }}"

      # Master turned on or attributes changed while on
      - conditions:
          - condition: template
            value_template: "{{ trigger.to_state.state == 'on' }}"
        sequence:
          - action: light.turn_on
            target:
              entity_id: "{{ followers }}"
            data:
              transition: "{{ transition }}"
              brightness_pct: >-
                {% set brightness = state_attr(master, 'brightness') %}
                {% if brightness is not none %}
                  {{ (brightness / 255 * 100) | round(0) }}
                {% else %}
                  {{ none }}
                {% endif %}
              color_temp_kelvin: >-
                {% set kelvin = state_attr(master, 'color_temp_kelvin') %}
                {% if kelvin is not none %}
                  {{ kelvin }}
                {% else %}
                  {{ none }}
                {% endif %}