Price + Weight blended logic (free over $X, heavy surcharge over Y grams)

{% liquid
  # Compose price and weight rules:
  # - Free if subtotal >= $75 (US only)
  # - Else base price
  # - If total weight > 5 kg, add $6 heavy surcharge

  # --- editable settings ---
  assign service_name = "Economy"
  assign service_code = "ECONOMY"
  assign currency = "USD"
  assign description = "Blended price & weight rules"
  assign base_price = 899                       # cents
  assign heavy_threshold_grams = 5000           # 5 kg
  assign heavy_surcharge = 600                  # cents
  assign free_over_cents = 7500                 # $75
  assign free_country = "US"                    # only free for this country

  # --- logic ---
  assign subtotal = 0
  assign total_grams = 0

  for item in shopify_rate_check.items
    assign line_price = item.price | times: item.quantity
    assign subtotal = subtotal | plus: line_price
    assign line_weight = item.grams | times: item.quantity
    assign total_grams = total_grams | plus: line_weight
  endfor

  assign shipping_price = base_price

  if shopify_rate_check.destination.country == free_country and subtotal >= free_over_cents
    assign shipping_price = 0
  endif

  if shipping_price > 0 and total_grams > heavy_threshold_grams
    assign shipping_price = shipping_price | plus: heavy_surcharge
  endif

  assign rate = rate | merge: "currency", currency
  assign rate = rate | merge: "service_name", service_name
  assign rate = rate | merge: "service_code", service_code
  assign rate = rate | merge: "total_price", shipping_price
  assign rate = rate | merge: "description", description

  assign rates = rates | array_append: rate
%}
{
  "rates": {{ rates | array_wrap | json }}
}