[in_app_purchase_storekit] purchase() and Transaction.updates both call sendTransactionUpdate(.purchased) causing duplicate “purchased” events and early purchased state #183583

Steps to reproduce

in_app_purchase_storekit: ^0.4.8+1 and in_app_purchase: ^3.2.3

1.Enable StoreKit2 path
2.Start listening to the purchase stream in Dart

InAppPurchase.instance.purchaseStream.listen((purchases) {
  // log or handle purchase events here
});

3.Trigger a StoreKit2 purchase

final result = await InAppPurchase.instance.buyNonConsumable(
  purchaseParam: purchaseParam,
);

Expected results

Expected single-purchase flow:

After calling purchase(id:options:):
You’ll receive only one “purchase successful” event. The business side can safely proceed with shipping based on this event (e.g., awarding in-game coins).
Transaction.updates is used for:
Handling scenarios involving purchases made outside the app, on other devices, or through restore functionality;
or handling historical/unfinished transactions.
It will not send another .purchased event for the same purchase within the current session that duplicates the one sent by purchase().
Expected status semantics:

status: .purchased indicates:
“This transaction has already been completed on the Store side and can be considered final at the game’s business layer, allowing for safe shipment.”
If certain callbacks merely indicate that “the transaction has been created/updated on the Store side but still requires a secondary confirmation UI logic within the game,” then these callbacks should have distinct semantics (or clearly documented instructions requiring the business layer to handle idempotency themselves).

Actual results

Under the StoreKit2 mode, the same purchase will trigger two calls to sendTransactionUpdate(..., status: .purchased):

1. First time: Inside the function "purchase(id:options:)"

let result = try await product.purchase(options: purchaseOptions)

switch result {
case .success(let verification):
  sendTransactionUpdate(
    productId: id,
    transaction: verification.unsafePayloadValue,
    receipt: verification.jwsRepresentation,
    status: .purchased
  )
case .pending:
  sendTransactionUpdate(productId: id, status: .pending)
case .userCancelled:
  sendTransactionUpdate(productId: id, status: .cancelled)
@unknown default:
  fatalError("An unknown StoreKit PurchaseResult has been encountered.")
}

2. Second time: Within the Transaction.updates event listened for in the startListeningToTransactions() method

func startListeningToTransactions() throws {
  self.setListenerTaskAsTask(
    task: Task { [weak self] in
      for await verificationResult in Transaction.updates {
        switch verificationResult {
        case .verified(let transaction):
          self?.sendTransactionUpdate(
            productId: transaction.productID,
            transaction: transaction,
            receipt: verificationResult.jwsRepresentation,
            status: .purchased
          )
        case .unverified:
          break
        }
      }
    })
}

The purchaseStream on the Dart side (or the upper-level IAP management logic) will receive two nearly identical "purchased" events:
If the business logic is "ship the goods and add gold whenever status == purchased", then the same transaction will be shipped twice.
A more crucial point is:
In actual experience, the second .purchased callback from Transaction.updates sometimes triggers before the "final confirmation dialog" of our own game:
From a business perspective, this event is more similar to the "purchasing" or "pending transactions" in SK1;
However, it is currently uniformly labeled as ".purchased", and it is difficult for the business side to distinguish between "final success for shipment" and "updates during the intermediate process" solely based on the "status".

Code sample

// lib/src/in_app_purchase_storekit_platform.dart

if (_useStoreKit2) {
  final updateController2 =
      StreamController<List<PurchaseDetails>>.broadcast(
        onListen: () => SK2Transaction.startListeningToTransactions(),
        onCancel: () => SK2Transaction.stopListeningToTransactions(),
      );
  _sk2transactionObserver = SK2TransactionObserverWrapper(
    transactionsCreatedController: updateController2,
  );
  InAppPurchase2CallbackAPI.setUp(_sk2transactionObserver);
} else {
  // SK1 ...
}

Screenshots or Video

Logs

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