Customer Facing Display briefly shows incorrect prices before Cart Transform completes

Extensions
1

Title: Customer Facing Display briefly shows incorrect prices before Cart Transform completes

We’re seeing a UX issue when using Cart Transform Functions in Shopify POS with the Customer Facing Display enabled.

When an item is added to the cart:

  • The item is immediately displayed with its original price.
  • Cart Transform then executes.
  • The line item’s price updates to the transformed value.
  • Customers see the price visibly change after it has already appeared.

The attached video demonstrates this behavior in the Shopify POS cart. A merchant using a Customer Facing Display has confirmed that the same sequence occurs there as well, making the price change highly visible to customers.

The merchant has reported that customers notice the sudden price change and often ask about it, creating confusion during checkout.

As more POS apps migrate to Cart Transform—particularly apps that dynamically calculate prices, such as weight-based selling or variable pricing—we expect more merchants using Customer Facing Display to encounter this issue.

Suggested improvement

If Shopify detects that the POS cart has one or more Cart Transform Functions installed, consider delaying the display of newly added line items on the Customer Facing Display until the Cart Transform has finished executing.

This would ensure customers only see the final transformed price, preventing sudden visual jumps and providing a smoother checkout experience.

Although the attached recording is from the POS cart rather than the Customer Facing Display, it illustrates the same behavior that the merchant is experiencing on the Customer Facing Display.

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Hey @teamfj-co - thanks for flagging this and for including the recording.

I definitely get the concern here. If the Customer Facing Display shows the original line price first and then updates once Cart Transform finishes, that can create a confusing checkout moment, especially for variable/weight-based pricing flows where the transformed price is the one the customer should actually be seeing.

I’m going to raise this on our end as a POS/Customer Facing Display display-timing issue. Before I do, could you share a few extra details so we can route it with the right context?

  • A short recording of the behavior on the Customer Facing Display itself, if you’re able to capture one
  • The POS app version, device/iOS version, and whether this happens on every add or only intermittently
  • Which Cart Transform operation your function is using (lineUpdate, lineExpand, or linesMerge) and the API version

If you’re open to sharing shop/app/function identifiers privately rather than in the thread, let me know and I can set up a DM.

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Thanks @Alan_G , we are using either lineUpdate or lineExpand depending on the merchant’s Shopify plan, but in this specific case it’s a non-Plus merchant who has raised this issue (lineExpand). We are using API version 2026-01. Happy to share shop / app / function identifiers as well if that’s useful for reproduction.

My teammate will provide the other info requested.

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Hi @Alan_G, here’s the recording from a merchant.

The POS app version is 11.9.1, device: iPad (10th gen), iOS version: 26.5 and it happens on every transaction.

Let us know if you need further information. Thank you!