script.liquid

{% assign tags_to_save = order.tags %}
{% assign order_skus = order.line_items | map: "sku" | uniq %}

{% for pair in options.tags_and_required_skus__keyval_required %}
  {% assign tag = pair[0] %}
  {% assign required_skus = pair[1] | split: "," %}

  {% assign matched_sku_count = 0 %}
  {% for order_sku in order_skus %}
    {% if required_skus contains order_sku %}
      {% assign matched_sku_count = matched_sku_count | plus: 1 %}
    {% endif %}
  {% endfor %}

  {% if event.preview or matched_sku_count == required_skus.size %}
    {% assign tags_to_save = tags_to_save | add_tag: tag %}
  {% endif %}
{% endfor %}

{% if event.preview or tags_to_save != order.tags %}
  {
    "action": {
      "type": "shopify",
      "options": [
        "update",
        [
          "order",
          {{ order.id | json }}
        ],
        {
          "tags": {{ tags_to_save | json }}
        }
      ]
    }
  }
{% endif %}