Sync Two Lights in HA

lights-sync.yaml

blueprint:
  name: Sync Two Lights (Bidirectional)
  description: >
    When either light changes (on/off, brightness, color temperature, or RGB),
    the other light is updated to match.
  domain: automation
  input:
    light_a:
      name: First Light
      description: One of the lights to sync.
      selector:
        entity:
          domain: light
    light_b:
      name: Second Light
      description: The other light to sync.
      selector:
        entity:
          domain: light

mode: restart

trigger:
  - platform: state
    entity_id:
      - !input light_a
      - !input light_b
    attribute: brightness
  - platform: state
    entity_id:
      - !input light_a
      - !input light_b
    attribute: rgb_color
  - platform: state
    entity_id:
      - !input light_a
      - !input light_b
    attribute: color_temp
  - platform: state
    entity_id:
      - !input light_a
      - !input light_b
    to: "on"
  - platform: state
    entity_id:
      - !input light_a
      - !input light_b
    to: "off"

action:
  - variables:
      light_a: !input light_a
      light_b: !input light_b
      triggered: "{{ trigger.entity_id }}"
      other: >
        {% if trigger.entity_id == light_a %}
          {{ light_b }}
        {% else %}
          {{ light_a }}
        {% endif %}
      triggered_state: "{{ states(triggered) }}"
  - choose:
      - conditions:
          - condition: template
            value_template: "{{ is_state(triggered, 'off') }}"
        sequence:
          - service: light.turn_off
            data:
              entity_id: "{{ other }}"
      - conditions:
          - condition: template
            value_template: "{{ is_state(triggered, 'on') }}"
        sequence:
          - choose:
              - conditions:
                  - condition: template
                    value_template: "{{ triggered_state.attributes.color_mode == 'rgb' }}"
                sequence:
                  - service: light.turn_on
                    data_template:
                      entity_id: "{{ other }}"
                      brightness: "{{ triggered_state.attributes.brightness | int(default=255) }}"
                      rgb_color: "{{ triggered_state.attributes.rgb_color }}"
              - conditions:
                  - condition: template
                    value_template: "{{ triggered_state.attributes.color_mode == 'color_temp' }}"
                sequence:
                  - service: light.turn_on
                    data_template:
                      entity_id: "{{ other }}"
                      brightness: "{{ triggered_state.attributes.brightness | int(default=255) }}"
                      color_temp: "{{ triggered_state.attributes.color_temp }}"
            default:
              - service: light.turn_on
                data_template:
                  entity_id: "{{ other }}"
                  brightness: "{{ triggered_state.attributes.brightness | int(default=255) }}"