fix: harden ios app build hygiene

apps/ios/Sources/Push/PushRelayClient.swift

@@ -24,7 +24,7 @@ enum PushRelayError: LocalizedError {
         case .unsupportedAppAttest:
             "App Attest unavailable on this device"
         case .missingReceipt:
-            "App Store receipt missing after refresh"
+            "App Store app transaction missing after refresh"
         }
     }
 }
@@ -85,33 +85,6 @@ private struct RelayErrorResponse: Decodable {
     var reason: String?
 }
 
-private final class PushRelayReceiptRefreshCoordinator: NSObject, SKRequestDelegate {
-    private var continuation: CheckedContinuation<Void, Error>?
-    private var activeRequest: SKReceiptRefreshRequest?
-
-    func refresh() async throws {
-        try await withCheckedThrowingContinuation { continuation in
-            self.continuation = continuation
-            let request = SKReceiptRefreshRequest()
-            self.activeRequest = request
-            request.delegate = self
-            request.start()
-        }
-    }
-
-    func requestDidFinish(_ request: SKRequest) {
-        self.continuation?.resume(returning: ())
-        self.continuation = nil
-        self.activeRequest = nil
-    }
-
-    func request(_ request: SKRequest, didFailWithError error: Error) {
-        self.continuation?.resume(throwing: error)
-        self.continuation = nil
-        self.activeRequest = nil
-    }
-}
-
 private struct PushRelayAppAttestProof {
     var keyId: String
     var attestationObject: String?
@@ -197,25 +170,27 @@ private final class PushRelayAppAttestService {
 
 private final class PushRelayReceiptProvider {
     func loadReceiptBase64() async throws -> String {
-        if let receipt = self.readReceiptData() {
-            return receipt.base64EncodedString()
+        do {
+            let result = try await AppTransaction.shared
+            return try Self.appTransactionBase64(result)
+        } catch {
+            let refreshed = try await AppTransaction.refresh()
+            return try Self.appTransactionBase64(refreshed)
         }
-        let refreshCoordinator = PushRelayReceiptRefreshCoordinator()
-        try await refreshCoordinator.refresh()
-        if let refreshed = self.readReceiptData() {
-            return refreshed.base64EncodedString()
-        }
-        throw PushRelayError.missingReceipt
     }
 
-    private func readReceiptData() -> Data? {
-        guard let url = Bundle.main.appStoreReceiptURL else { return nil }
-        guard let data = try? Data(contentsOf: url), !data.isEmpty else { return nil }
-        return data
+    private static func appTransactionBase64(
+        _ result: StoreKit.VerificationResult<AppTransaction>) throws -> String
+    {
+        let jws = result.jwsRepresentation.trimmingCharacters(in: .whitespacesAndNewlines)
+        guard !jws.isEmpty else {
+            throw PushRelayError.missingReceipt
+        }
+        return Data(jws.utf8).base64EncodedString()
     }
 }
 
-// The client is constructed once and used behind PushRegistrationManager actor isolation.
+/// The client is constructed once and used behind PushRegistrationManager actor isolation.
 final class PushRelayClient: @unchecked Sendable {
     private let baseURL: URL
     private let session: URLSession
@@ -294,8 +269,7 @@ final class PushRelayClient: @unchecked Sendable {
                 status: status,
                 message: Self.decodeErrorMessage(data: data))
         }
-        let decoded = try self.decode(PushRelayRegisterResponse.self, from: data)
-        return decoded
+        return try self.decode(PushRelayRegisterResponse.self, from: data)
     }
 
     private func fetchChallenge() async throws -> PushRelayChallengeResponse {