Quick answer
KitForge FBT and quantity break discounts run through Shopify Discount Functions at checkout. Fixed kit bundles use Cart Transform to expand parent lines into component SKUs with kit-level pricing. Understanding both layers prevents confusion when debugging cart totals.
- FBT and QB discounts are Shopify Discount Functions — not Liquid theme discounts.
- Fixed kits rely on Cart Transform for line structure and kit pricing.
- Widget-only mode ties discount eligibility to widget-initiated adds.
- Always test checkout after changing discount labels or tier percentages.
Why KitForge splits Cart Transform and Discount Functions
Shopify's Functions platform assigns different capabilities to cart transform and discount runtimes. KitForge uses each for what Shopify supports natively — kit line expansion via transform, percentage or fixed discounts on FBT/QB via discount functions.
This architecture keeps checkout authoritative: the storefront widget displays expected prices, but checkout functions enforce them.
Coexistence with other discount apps
Shopify applies discount stacking rules at checkout. Test carts when automatic discounts, discount codes, and KitForge widget discounts could overlap on the same lines.
KitForge does not support BOGO or free-gift mechanics — only fixed kit, FBT, and quantity breaks.
Final recommendation
KitForge's integration with Shopify Functions is split by offer type: Cart Transform for fixed kits, Discount Functions for FBT and quantity breaks. Test both paths before campaigns.
If you want this kind of offer to feel native to the buying journey, Kitforge Bundles is built around that exact problem: turning related Shopify products into clearer bundle offers before the shopper reaches checkout.
FAQ
Can I use Shopify automatic discounts with KitForge QB?
Test in checkout — Shopify resolves competing discounts per its stacking rules. KitForge tier discounts apply via Functions when widget conditions are met.
Why does fixed kit pricing not use Discount Functions?
Kit pricing and component expansion are handled in Cart Transform so fulfillment sees correct child SKUs with kit-level line structure.