Cart and checkout

In Randio Open Settings → Sync

A catalog price has to survive from the catalog page to the paid order. Three pieces make that happen, and all three show their status in Settings → Sync.

How a discount travels

The customer adds a product from their catalog page or the storefront block. The cart line is marked as a Randio line for that catalog. Only lines added from a Randio page or block carry the price; the same product added from your theme's own product page is full price.
The cart app embed checks the cart with Randio and writes a short-lived, signed token into the cart. The token lives five minutes; the embed refreshes it every three minutes while the tab is open and again whenever the cart changes.
At checkout, Randio's automatic app discount reads the token and prices every Randio line at that customer's catalog price. The checkout shows the saving as a discount line per item. Gift cards are never discounted.

If the app embed is off, step 2 never happens and the shopper sees full prices. If the discount is not registered, step 3 never happens. Settings → Sync shows Register now when that is the case.

Rules the cart follows

One discounted unit per product. The Discount Quantity Limit in Settings → Preferences sets it for every strategy, and a distribution can set its own Max per product. The limit is per product per catalog, shared across the product's variants and drawn in the order the lines were added; units beyond it stay in the cart as a separate line at full price.
A cart follows one catalog at a time. Adding from a newer catalog moves the discounts to that catalog. Items from the previous one stay in the cart, undiscounted, unless the newer catalog offers the same product, in which case the line takes the new price.
Nothing is removed. When a run ends or a product leaves the catalog, the line stays and the discount drops. The customer decides what to do with it.
A catalog dies with its run. After the end time the token no longer validates, even if a cart kept it, and a token older than a week is refused in any case.
Previously bought products can be kept out of new catalogs with Settings → Inventory → Exclude Previously Ordered Products and its exclusion window.

Two devices

A customer who opens the same catalog on a second device sees it move with them. The device that last added to the cart holds the offers, except while a checkout is under way on the other one.

When prices do not apply

Check, in this order: the app embed is on; the checkout discount is registered; the run is still live; the product is in that customer's catalog and was added from a Randio page or block; it is not a gift card; the unit is within the per-product limit. The order detail page shows "Limit: N of M discounted" when the limit was the cause.