Add Transaction.unfinished API and expose appAccountToken in SK2PurchaseDetails

This PR adds two new features to in_app_purchase_storekit for StoreKit 2:

1. SK2Transaction.unfinishedTransactions() - Queries only unfinished transactions,
   mirroring Apple's Transaction.unfinished API for better performance.

2. SK2PurchaseDetails.appAccountToken - Exposes the UUID that associates
   transactions with users in custom backend systems.

Both features are additive and maintain full backward compatibility.

Tests included for both features.

Author: Haidar0096

packages/in_app_purchase/in_app_purchase_storekit/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 0.4.7
+
+* Adds `SK2Transaction.unfinishedTransactions()` method to query only unfinished transactions.
+* Exposes `appAccountToken` property in `SK2PurchaseDetails` for user identification.
+
 ## 0.4.6+2
 
 * Updates to Pigeon 26.

packages/in_app_purchase/in_app_purchase_storekit/darwin/in_app_purchase_storekit/Sources/in_app_purchase_storekit/StoreKit2/InAppPurchasePlugin+StoreKit2.swift

@@ -230,6 +230,22 @@ extension InAppPurchasePlugin: InAppPurchase2API {
     }
   }
 
+  /// Wrapper method around StoreKit2's Transaction.unfinished
+  /// https://developer.apple.com/documentation/storekit/transaction/unfinished
+  func unfinishedTransactions(
+    completion: @escaping (Result<[SK2TransactionMessage], Error>) -> Void
+  ) {
+    Task {
+      @MainActor in
+      do {
+        let transactionsMsgs = await rawUnfinishedTransactions().map {
+          $0.convertToPigeon(receipt: nil)
+        }
+        completion(.success(transactionsMsgs))
+      }
+    }
+  }
+
   func restorePurchases(completion: @escaping (Result<Void, Error>) -> Void) {
     Task { [weak self] in
       guard let self = self else { return }
@@ -362,6 +378,20 @@ extension InAppPurchasePlugin: InAppPurchase2API {
     return transactions
   }
 
+  /// Helper function that fetches and unwraps all verified unfinished transactions
+  func rawUnfinishedTransactions() async -> [Transaction] {
+    var transactions: [Transaction] = []
+    for await verificationResult in Transaction.unfinished {
+      switch verificationResult {
+      case .verified(let transaction):
+        transactions.append(transaction)
+      case .unverified:
+        break
+      }
+    }
+    return transactions
+  }
+
   /// Helper function to fetch specific transaction
   func fetchTransaction(by id: UInt64) async throws -> Transaction? {
     for await result in Transaction.all {

packages/in_app_purchase/in_app_purchase_storekit/darwin/in_app_purchase_storekit/Sources/in_app_purchase_storekit/StoreKit2/StoreKit2Messages.g.swift

@@ -73,7 +73,7 @@ private func nilOrValue<T>(_ value: Any?) -> T? {
   return value as! T?
 }
 
-func deepEqualsStoreKit2Messages(_ lhs: Any?, _ rhs: Any?) -> Bool {
+func deepEqualssk2_pigeon(_ lhs: Any?, _ rhs: Any?) -> Bool {
   let cleanLhs = nilOrValue(lhs) as Any?
   let cleanRhs = nilOrValue(rhs) as Any?
   switch (cleanLhs, cleanRhs) {
@@ -114,7 +114,7 @@ func deepEqualsStoreKit2Messages(_ lhs: Any?, _ rhs: Any?) -> Bool {
   }
 }
 
-func deepHashStoreKit2Messages(value: Any?, hasher: inout Hasher) {
+func deepHashsk2_pigeon(value: Any?, hasher: inout Hasher) {
   if let valueList = value as? [AnyHashable] {
     for item in valueList { deepHashStoreKit2Messages(value: item, hasher: &hasher) }
     return
@@ -727,6 +727,8 @@ protocol InAppPurchase2API {
   func isIntroductoryOfferEligible(
     productId: String, completion: @escaping (Result<Bool, Error>) -> Void)
   func transactions(completion: @escaping (Result<[SK2TransactionMessage], Error>) -> Void)
+  func unfinishedTransactions(
+    completion: @escaping (Result<[SK2TransactionMessage], Error>) -> Void)
   func finish(id: Int64, completion: @escaping (Result<Void, Error>) -> Void)
   func startListeningToTransactions() throws
   func stopListeningToTransactions() throws
@@ -860,6 +862,24 @@ class InAppPurchase2APISetup {
     } else {
       transactionsChannel.setMessageHandler(nil)
     }
+    let unfinishedTransactionsChannel = FlutterBasicMessageChannel(
+      name:
+        "dev.flutter.pigeon.in_app_purchase_storekit.InAppPurchase2API.unfinishedTransactions\(channelSuffix)",
+      binaryMessenger: binaryMessenger, codec: codec)
+    if let api = api {
+      unfinishedTransactionsChannel.setMessageHandler { _, reply in
+        api.unfinishedTransactions { result in
+          switch result {
+          case .success(let res):
+            reply(wrapResult(res))
+          case .failure(let error):
+            reply(wrapError(error))
+          }
+        }
+      }
+    } else {
+      unfinishedTransactionsChannel.setMessageHandler(nil)
+    }
     let finishChannel = FlutterBasicMessageChannel(
       name: "dev.flutter.pigeon.in_app_purchase_storekit.InAppPurchase2API.finish\(channelSuffix)",
       binaryMessenger: binaryMessenger, codec: codec)