# Handling Storefront & Price Changes

A purchase can be enqueued in one storefront but execute in another — for example, a logged-out user starts a purchase with their device region, then logs into an account registered in a different country, where the price or availability differs.

OnsideKit does **not** silently charge the new price. Before processing such a purchase, it asks your **payment queue delegate** whether to continue, so you can confirm the change with the user or cancel it.

## The delegate

```swift
protocol OnsidePaymentQueueDelegate: AnyObject {
    @MainActor func onsidePaymentQueue(
        _ queue: OnsidePaymentQueue,
        shouldContinue transaction: OnsidePaymentTransaction,
        in storefront: OnsideStorefront
    ) -> Bool

    @MainActor func onsidePaymentQueue(
        _ queue: OnsidePaymentQueue,
        shouldContinue transaction: OnsidePaymentTransaction,
        in storefront: OnsideStorefront
    ) async -> Bool
}
```

Both a synchronous and an asynchronous variant are available — implement whichever fits. The default implementation returns `true` (always continue), and the async default forwards to the sync one.

{% hint style="info" %}
The gate fires **only** when a queued transaction would execute in a storefront different from the one it was enqueued in. Same-storefront purchases proceed without calling the delegate.
{% endhint %}

* Return `true` — the transaction proceeds in the new storefront.
* Return `false` — the transaction is discarded.

## Implement the gate

Assign a delegate to the queue (keep a strong reference — the delegate is held weakly):

```swift
Onside.defaultPaymentQueue().delegate = self
```

Use the `async` variant to confirm with the user before continuing:

```swift
extension StoreCoordinator: OnsidePaymentQueueDelegate {
    func onsidePaymentQueue(
        _ queue: OnsidePaymentQueue,
        shouldContinue transaction: OnsidePaymentTransaction,
        in storefront: OnsideStorefront
    ) async -> Bool {
        let newPrice = transaction.payment.product.price
        return await confirmPriceChange(
            to: newPrice,
            region: storefront.countryCode
        )
    }

    @MainActor
    private func confirmPriceChange(to price: OnsidePrice, region: String) async -> Bool {
        // Present an alert: "The price is now \(price.value) \(price.currencyCode)
        // for region \(region). Continue?" and return the user's choice.
        return await withCheckedContinuation { continuation in
            // ... present UI, resume with true/false ...
        }
    }
}
```

If you don't set a delegate, OnsideKit continues by default (as if you returned `true`).

## Related

* [Regions & Storefronts](/sdk/products-and-subscriptions/regions-and-storefronts.md) — how the region is resolved and why it can change
* [The Payment Queue & Transactions](/sdk/core-concepts/payment-queue.md) — the queue resets and notifies `onsidePaymentQueueDidChangeStorefront` when the storefront changes


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